Lignin: what it is, main properties and uses. Hydrolytic lignin

The preparation Lignin hydrolysis has a high adsorption effect.

Lignin hydrolysis description

The preparation is obtained through the process of wood processing. The drug Lignin hydrolysis comes on sale in the form of granules or powder in individual packages of 10 grams, as well as packaged in 50 grams in glass jars. In addition, you can purchase hydrolytic lignin in tablet form at the pharmacy. They can be packaged in various quantities in blisters from 10 to 100 pieces.

Pharmacology

The drug Lignin hydrolysis has a fairly high sorption activity and a nonspecific detoxification effect.

Its therapeutic activity consists of binding and removing pathogenic bacteria and bacterial toxins from the body, as well as medications, poisons, heavy metal salts, alcohol and allergens.

In addition, the drug is able to absorb excesses of certain metabolic products in the body, such as bilirubin, cholesterol, urea, metabolites, as a result of an excess of which endogenous toxicosis can develop.

The drug itself is not absorbable and has no toxicity. Within 24 hours, it is completely eliminated from the intestinal tract.

Hydrolytic lignin indications for use

Lignin is indicated for use in the following pathological conditions:

• As a detoxifying agent for exogenous and endogenous toxicosis of various origins;
• In order to provide first aid in case of acute poisoning by any of the poisons, be it a drug, an alkaloid, salts of heavy metals, alcohol and others;
• To participate in the complex treatment of food poisoning, salmonellosis, dysentery, dysbacteriosis, dyspepsia, as well as purulent-inflammatory diseases that may be accompanied by intoxication;
• When liver and kidney failure is detected;
• When lipid metabolism disorders occur with a diagnosis of atherosclerosis and obesity;
• For use in the treatment of food and drug allergic disorders;
• In order to remove xenobiotics from the body.

Contraindications Hydrolytic lignin

The drug Lignin hydrolysis is contraindicated for use only if it is individually intolerant.

Lignin hydrolysis application

For treatment, Lignin is prescribed for oral administration before meals and the use of other medications at least an hour before. The drug must be dissolved in water or washed down with it. The dosage of the drug is calculated depending on the severity of the disease at the rate of 1 gram of the drug per 1 kilogram of body weight. The received dose of the drug is divided into several doses.

The average dosage of the drug is:

For infants, 0.5-1 teaspoon;

For children from 1 to 7 years of age, 1 dessert spoon;

For children over 7 years of age and adults, 1 tablespoon per single dose three times a day.

If an acute condition is observed, the course of treatment should be at least five days. When there is an exacerbation of chronic intoxication or an allergic disease, the drug intake is increased to two weeks.

If it is necessary to prescribe a second course of treatment, treatment should be resumed no earlier than two weeks later.

Side effects and drug interactions

Occasionally, constipation and allergic reactions were observed as side effects when taking the drug.

With prolonged use of hydrolytic lignin, which exceeds 20 days, impaired absorption of calcium and vitamins may develop. In order to avoid this, when treating with enterosorbent, you should take prophylactic multivitamin and calcium preparations.

With simultaneous use, a reduced therapeutic effect of some drugs may be observed.

Lignin hydrolysis precaution

The drug is not prohibited, but it is undesirable to use it for treatment in cases where there is intestinal atony, antacid gastritis and there has been a period of exacerbation of peptic ulcers of the gastrointestinal tract.

Hydrolyzed lignin price

The price of the drug Lignin is low and practically does not exceed one hundred rubles per package, which contains 20 individual sachets.

Hydrolytic lignin reviews

Reviews about the drug Lignin are only positive, especially many of them are left by those people who have experienced the delights of alcohol poisoning and allergies. Here are the latest ones:

Vasilyeva: In the evening, friends gathered and, as usual, quickly organized a party. I’m not particularly keen on alcohol, but my husband doesn’t mind relaxing. If you overdo it, that morning, of course, will be marked by a severe hangover. That's how it happened this time. However, the situation was aggravated by the fact that in the morning we had to go to the city. I had to run to the pharmacy and explain the situation. They offered hydrolytic lignin powder. I bought it for a one-time use because the price was cheap, and I honestly doubted its effectiveness. However, the drug did not justify my fears and put my husband back on his feet very quickly. So now I keep it in my medicine cabinet all the time.

At the current level of consumption of forest resources, the factor of their full use is fundamental. Of the three main areas of wood processing: as building materials, fuel and a source of raw materials for chemical products, the latter accounts for 13% of the world's harvesting volume, or about 2.6 billion m 3. But of this amount, only carbohydrate components are still effectively used. Produced as a by-product during the production of sulfate pulp are 40 million tons/year of lignin, 5 million tons/year of technical lignosulfates (TSL - dry matter of sulfite liquors from pulp and paper production waste) and 3.5 million tons/year of technical hydrolytic lignin (THL) 65 % humidity is qualifiedly used at only 0.1%. Basically, these products, called waste, are burned or disposed of in a landfill.

At the same time, as production expands and new evaporation shops are launched, the yield of TSL can reach 3.0 million tons/year, and in connection with the development of hydrolysis-yeast production, the yield of TGL will increase in the CGP five-year plan to 9-10 million tons/year (humidity 65%). It should be borne in mind that when processing wood, these wastes are active disruptors of the ecological balance of the environment, therefore, determining ways of recycling lignin waste from the pulp and paper and hydrolysis industries is the most important national economic task. First of all, when developing directions for recycling, one should take into account the carbon-containing nature of these materials, their reactivity towards oxygen and hydrogen-carbon complexes, and the ability to create biologically active compounds.

1.1. CHARACTERISTICS OF WASTE HYDROLYSIS PRODUCTION

At hydrolysis plants (HP), in the process of chemical catalytic processing of wood waste (chips and sawdust) and agricultural raw materials (corn cobs, sunflower and rice husks, cotton husks, etc.), as a result of hydrolysis, polysaccharides turn into monosaccharides - pentose and hexose:

1) conversion of hexosanes to hexose

2) conversion of pentosans to pentose

The main products of hydrolysis plants, depending on the direction of processing, are protein yeast, ethyl alcohol, furfural and its derivatives, xylitol, polyhydric alcohols and carbonates, which determines the profile of the plants. At the same time, the waste yield reaches 80% of the consumed raw materials.

Hydrolysis of plant raw materials is carried out in periodically operating apparatus by percolating a 0.5-1.0% solution of sulfuric or hydrochloric acid through a layer of wood at a temperature of saturated water vapor equal to 180-185 ° C. Acid solutions act as catalysts for the process.

Wood and agricultural waste of any kind can be used in the yeast profile, since the ratio of pentose and hexose sugars does not matter for yeast strains. At the alcohol-yeast profile, it is necessary to process mainly a mass of coniferous wood, the hydrolysis of which produces more hexose sugars, which are necessary for alcohol-producing yeast strains when fermenting into ethyl alcohol. For furfural-yeast and xylitol-yeast profiles, deciduous wood and agricultural waste containing more pentose sugars are used.

It should be noted that the entire mass of raw materials used for hydrolysis is contaminated with earth and sand during transportation and storage in open areas of the civil protection plant. In addition, superphosphate is supplied to hydrolysis apparatuses, the solution of which must be prepared outside these apparatuses. As a result, the ash content in TGL increases, which worsens its commercial qualities.

The following large-scale wastes are generated in hydrolysis production: THL, sludge, primary sewage sludge accumulated in primary settling tanks, excess activated sludge formed after biological wastewater treatment, and industrial wastewater.

According to the data, for a gas plant with a productivity of 28 thousand tons/year of feed yeast, the amount of solid waste generated per day based on abs. dry matter is approximately (t): TGL-130, sludge - 80, primary sediment - 12, excess activated sludge - 16. In addition, approximately 25-30 thousand m 3 /day of industrial wastewater is formed. THL is one of the largest hydrolysis production wastes and accounts for 30-40% of the mass of processed raw materials.

1.1.1. TGL structure

THL is a very complex and sometimes unpredictable mixture of substances from the hydrolytic breakdown of plant residues. It includes the non-hydrolyzable part of the raw material, lignin itself, part of the difficult-to-hydrolyze polysaccharides, reducing substances (monosaccharides, furfural), partially resins, waxes, fats, ash residues, residues of sulfuric and organic acids, humic substances, moisture (up to 70%). The granulometric composition of TGL varies widely. The composition and properties of THL vary from cooking to cooking, so its analytical characteristic is an average statistical value. According to VNIIGidroliza, the content of individual groups of substances in TGL varies within the following limits (%):

To better understand the properties of TGL, it is necessary to study the chemistry and structure of lignin itself, which determines many of the mechanical properties of wood. In recent years, a large number of studies have been devoted to the study of the chemical structure of natural lignin, which has led to significant advances in this area.

The cell wall of plant tissue is a complex biochemical complex that can be considered as a kind of graphpolymer formed by cellulose, lignin, hemicelluloses, and polyuronides. Using modern physical methods of studying cell morphology, it was established that this is a product of an aromatic structure. When studying the place of lignin formation in plants, Manskaya showed that the first stages of lignification are possible not only in the cambium, but also in any meristematic (capable of division) tissue. As a result, lignification in the plant organism takes place not only in cell walls, but also in stony cells, sclerenchyma fibers, bark, cork, etc.

IN
In the light of modern ideas, lignin cannot be considered as a constitutionally defined compound formed as a result of the polymerization of uniform structural units. According to Shorygina, lignin is a mixture of lignin substances, just as protein substances exist in nature. Recently, according to Freudenberg's proposal, lignin substances are called polylignols. Thus, lignin is understood as natural polymer products formed by spontaneous dehydrogenation polycondensation of mono- and oligolignols (di-, tri-, tetra-, etc.). Three main starting principles act as monolignols: n-coumaric (/), coniferyl (//), synapic (///) derivatives of cinnamic alcohol:

In this process, the lignin macromolecule is formed as a result of the combination of phenoxyl radicals, similar to other phenolic natural substances. Lignin is not a homopolymer, but a copolymer, since it is formed from three monomers, differing only in the presence of one or two methoxyl groups.

It should be noted that natural lignins are subject to significant changes even under mild chemical influence, so a method has not yet been found that allows lignin to be completely isolated from plants without changing its chemical structure.

Based on experiments on the production of artificial lignin through the enzymatic dehydrogenation of coniferyl alcohol, a structure diagram of spruce lignin was proposed. This structure is considered the most successful of all known hypothetical structures (Fig. 1-1). Naturally, it cannot be considered as the true formula of lignin, however, with its help you can understand the nature of the bonds in the lignin macromolecule. Recently, it has been used to simulate lignin formation reactions on a computer. Moreover, the authors proceeded from the generally accepted principles that lignin is a three-dimensional branched network polymer synthesized by plants. The enzymatically initiated combination of phenol was considered to be the driving force behind polymerization.

A detailed analysis of the modern understanding of the macromolecular structure of lignins was carried out by J. A. Gravitis at the Institute of Wood Chemistry of the Academy of Sciences of the Latvian SSR. It is based on the idea of ​​lignin as a branched network polymer immersed in a carbohydrate environment. Using modern research methods, the author examines structural levels that affect the topological and supramolecular structure of network polymers.

Interesting data were obtained by using the electron spectroscopy method for the chemical analysis of lignin. For example, this method allowed new evaluation of the original data on the distribution of lignin in various analytical quantifiable elements of wood. Using modern research methods, as well as the latest data on the macromolecular structure of lignin, J. A. Gravitis, together with P. P. Erins, created a model of lignin, according to which it has a pronounced heterogeneous cross-linking.

To quantitatively characterize lignin heterogeneity, the so-called fractal dimension can be used. For the first time, lignin as a fractal volume (an object with a fractional dimension) was studied by V. G. Ozol-Kalnin. They considered the lignin model by analogy with particle-cluster or cluster-cluster aggregation models. Considering that the lignin in the cellular shell is only part of the whole, the macromolecular components of the shell were represented as a semi-interpenetrating network system.

Thus, studies of lignin using modern polymer physics methods have made it possible to evaluate the structure of lignin in a new way and significantly complement traditional methods for studying this complex natural substance. Computer modeling of lignin by combining all the most reliable data on the structure of this natural polymer showed that it already consists of 80 structural units instead of the 18 found previously.

Rice. 1-1. Scheme of the structure of lignin according to Freudenberg

According to Evilevich, Raskin et al., natural lignin of plant tissue can be considered as a disordered polymer built from structural elements of oxygen derivatives of phenylpropane, partially methoxylated or non-methoxylated. The products that make up lignin are united by common chemical characteristics, but at the same time they lack many important physical characteristics inherent in a constitutionally defined substance.

1.1.2. Main properties of TGL

The molecular weight of natural lignins is relatively high and is on the order of several thousand, but lower than the weight of technical lignins. They have a fairly porous structure and a developed specific surface area.

Based on the study of the chemical nature of lignin, its tendency to condense, in contrast to cellulose and hemicelluloses, is explained primarily by the presence in its molecule of labile side propane chains with hydroxide, ether, aldehyde, ketone, carboxyl and other functional groups, as well as the presence of benzene rings reactive phenolpropane structural units. In addition, functional groups that arise during the degradation of the polymolecule, as well as during the opening of cyclic structures of the pinoresinol and phenylcoumaron type, are reactive. Thus, as it heats up, a loss of lignin thermoplasticity is observed, which is explained by the occurrence of condensation reactions and the transition to an insoluble state. The melting point of lignins is in the range of 125-255°C and depends on the molecular weight and their moisture content. Thus, the melting point of dry dioxane lignin is 130, for wet one - 50 °C.

Hydrolysis of wood comes down to the process of steam cooking raw materials, previously moistened when loading with a solution of sulfuric or hydrochloric acid. During hydrolysis, profound changes occur in the lignocarbohydrate matrix of the cellular walls of wood. At 50-60°C, hemicelluloses will begin to soften, and at 90-100°C, lignin itself will begin to soften, and it will go into a viscous-flowing state.

High-molecular lignin in hot solutions of sulfuric acid is not peptized and, after removing most of the hydrolyzed carbohydrates by percolation, it is removed (shot) from the apparatus. Under the influence of hot solutions of sulfuric acid, the phenomena of coalescence of lignin globules and the formation of new intramolecular carbon-carbon bonds, including conjugated ones, are observed, which complicates and densifies the structure of wood lignin.

Chudakov’s works show that in the process of hydrolysis, lignin-carbohydrate bonds are broken and the overall lignin network is destroyed. Due to unused functional groups, conversion occurs, secondary aromatic structures are formed and, as a result, the reactivity of lignin sharply decreases.

TGL differs significantly from native and technical lignins obtained during the production of cellulose. It has a significantly lower content of main functional groups except methoxy groups, which are resistant to hydrolysis. Thus, THL obtained from coniferous wood contains the following groups (%): methoxy - 10-11, acidic - 9-14, hydroxyl - 6-8, carboxyl - 5-6 and about 3 - phenolic. THL is insoluble in alkalis and polar solvents; Unlike natural ones, THL, when oxidized with alkaline permanganates, forms benzenepolycarboxylic acids. This property of THL is very important when assessing it as a raw material for chemical processing and use in the national economy.

TGL differs from carbohydrates in its high carbon content, which increases during the condensation process. Its elemental composition varies widely. Practice has established that these fluctuations depend more on the method and mode of extraction than on the nature of the wood (Table 1.1).

As a result of the study of functional groups and the study of deep oxidation products, the work provides a scheme for the construction of a THL fragment. (Fig. 1-2). As the author points out, this scheme can be used to predict certain directions of lignin processing, to explain the formation of secondary structures and the accumulation of conjugated bonds that determine the nature of radicals determined by the EPR method.

Table 1.1. Elemental composition of THL from a number of hydrolysis plants

In accordance with the above scheme, it can be foreseen that during the carbonization of TGL, various types of coals can be obtained. With light oxidation, vanillin can be obtained, and with deep oxidation, oxalic acid can be obtained. Based on the condensed structure of THL, it is possible to obtain quinone products with biostimulant properties. As a result of oxidative modification or copolymerization, THL is capable of being converted into products needed for agriculture.

Based on the diagram, it is possible to predict the possibility of forming a strong monolithic piece during its briquetting due to additional cross-linking of individual TGL fragments into free functional groups. Wet THL can be considered as a three-phase polydisperse system: solid - water - air.

The dispersity of THL depends mainly on the fractional and botanical composition of the processed raw materials. It ranges from a few centimeters to several micrometers. More than 60% of the TGL mass is represented by a fraction less than 1 mm (Table 1.2).

Rice. 1-2. Scheme of the structure of hydrolytic lignin

The density of TGL ranges from 1.3.5-1.4 g/cm 3 . THL is a hydrophilic substance that can swell in water and other solvents in much the same way as cellulose and hemicellulose. The specific surface area of ​​wood and its components in a state of swelling is characterized by the following data (m 2 /g): native lignin - 180-280, wood - 215, lignin - 177, cellulose - 164, cellolignin - 152.

Due to its developed porous structure, TGL has pronounced sorption properties. Thus, the ability of THL to sorb vapors of organic solvents, phenols, etc. has been noted. This also determines the tendency of THL to undergo processes of physical adsorption and swelling. According to the data, the maximum degree of adsorption of water vapor at saturation for dried THL is 110-120 mg/g.

Table 1.2. Dispersity of THL

The structural and mechanical properties of TGL significantly depend on its moisture content, dispersion, external pressure and other factors. Under the influence of mechanical loads, a volumetric compaction of the material mass occurs, an increase in the number of contacts between particles and, as a result, a strengthening of its structural frame. The most important thing in the TGL molding process is its humidity, which determines the pressing pressure. Thus, when granulating TGL in dies, where a pressure of about 2.5-3.0 MPa develops, to create the most durable structure of the granule, the humidity should be approximately 50%, and when briquetting on high-pressure presses at 100-120 MPa, TGL should contain 10-18% moisture per working mass.

Thus, taking into account the physical and mechanical properties of TGL, as a polydisperse multiphase system capable of structuring at certain moisture content, pressing pressure and dispersion, it is possible to determine the technology for its agglomeration in order to obtain agglomerated lignoproducts with the specified properties required by the consumer.

When obtaining coal from agglomerated TGL, one should take into account the presence of a ready-made three-dimensional structure, which can be used directly during mechanical pressing and, under thermal influence, built up to a deeply aromatized structure of the coal.

When assessing THL as a raw material for the chemical industry, one should keep in mind the ability of its polymolecule to undergo oxidative-hydrolytic degradation. Despite the harsh acid treatment, THL contains a significant number of reactive and esterified phenolic and aliphatic hydroxide groups and unsubstituted carbons of phenylpropane lignin units. In this regard, lignin easily interacts with electrophilic reagents with the introduction of additional ionogenic groups into the molecule, and also undergoes oxidative-hydrolytic cleavage in acidic and alkaline environments. Therefore, as the authors point out, one of the main directions for processing THL should be its modification.

In addition, the presence in the structure of THL of a significant number of hydroxide and ether groups determines its ability to form chelates with the formation of intramolecular hydrogen bonds. Such products can be considered as active composites in the production of polymers.

1.2. INDUSTRIAL DISPOSAL OF TGL

Currently, three main directions for the industrial use of TGL have been identified: in their natural form without and after mechanical processing, through thermal and chemical processing. The main part of hydrolyzed lignin is used as boiler fuel, which is extremely irrational. Therefore, the most promising ways of using this valuable raw material for many sectors of the national economy will be given below.

1.2.1. Chemical processing of TGL

A very promising direction for the use of THL is that associated with its chemical transformations. In recent years, a large amount of research and pilot work has been carried out to create a technology for the chemical processing of lignin.

Since THL is a natural polymer, the main research was aimed at finding ways to modify it in order to obtain, without destruction, valuable structures that are similar in composition and properties to groups of substances that can be used without prior separation. This makes it easier to find large-scale consumers of destruction products.

Among various methods for the destruction of lignin, the cheapest and most promising is its oxidation, which leads to the rupture of C-O- and C-C bonds and the enrichment of newly formed fragments with oxygen-containing functional groups.

A significant change in the chemical composition of lignin and giving it new properties is possible through its co-condensation with various oligomer-polymers, as well as when producing polymers in the presence of lignin as a substrate. It is indicated that such methods of modifying lignin provide the creation of materials with controlled properties.

The combination of polymer and electrolyte properties in lignins opens up new possibilities for targeted modification by obtaining polyelectrolyte complexes, which increases, for example, the effectiveness of the action of lignosulfonates on dispersed systems (cement plasticizers, soil structure formers). It has also been shown that lignin’s own polyfunctionality and the introduction of new functional groups make it possible to use it not as a passive filler for polymer mixtures, but as an active component of press powders in the production of plastics.

Of great interest are studies on the use of lignins, including modified ones, as components of polymer compositions containing biologically active substances, for example, herbicides, insecticides, enzymes, etc.

The choice of direction for chemical processing of THF should be determined taking into account a number of factors. First of all, the economic efficiency of the process, the stability and availability of reagents for modifying lignin and their toxicity. At the same time, the process should be simple from the point of view of organizing technological equipment, as well as compliance with environmental requirements.

In the hydrolysis industry, in pilot or industrial conditions, technologies for the chemical processing of lignin have been used, such as the production of nitrolignin, colloctivite (brightening coals, ammonium salts of polycarboxylic acids, lignostimulating fertilizers). Schemes for the production of oil demineralizers and demulsifiers, stabilizers for special solutions, ingredients for compositions of high-molecular compounds, plant protection products, sorbents, etc. are being designed.

The technology for producing nitrolignin - a product of nitration and oxidation of THL with 8-10% nitric acid at 40-50 °C - was developed at the Institute of Organic Chemistry of the USSR Academy of Sciences.

Nitrolignin is used in the oil and gas industry as an active regulator of the structural and mechanical properties of clay solutions when drilling oil wells instead of synthetic preparations such as PFLKh-1 and UshchR. The use of nitrolignin during drilling can significantly reduce the costs of alkali, reagent and weighting agent, improve working conditions for drillers, and also obtain a significant economic effect. In addition, nitrolignin can be used as a tanning agent, filler, vaporizer and viscosity reducer in the cement and construction industries.

There are two methods for producing nitrolignin: dry and wet. Using the wet method, nitrolignin is obtained by oxidation and nitration of TGL with a nitro mixture containing 8-10% nitric and 2-4% sulfuric acids. According to the dry, more productive method, TGL is treated with concentrated nitric acid or melange with stirring. The quality of the manufactured product meets the requirements of MRTU 59-11-69.

To improve the properties of nitrolignin and give it the ability to dissolve in water, a technology for producing a new product - igetan - has been developed and implemented. This product is an active viscosity reducer for clay solutions; it is more convenient to use, as it is able to dissolve in water. This effect is achieved by additional oxidation of nitrolignin with a mixture of alkali and atmospheric oxygen. In this case, the destruction of the nitrolignin macromolecule occurs and new ionogenic functional groups appear.

The technology for producing igetan consists of mixing nitrolignin with a moisture content of no more than 60% in a speck reactor with soda supplied in an amount of 30% relative to the original nitrolignin. Igetan is produced in the form of a paste with a yield of 97-98% of nitrolignin.

Nitrolignin is an intermediate product for the production of another surfactant - sunil. This product is formed by sulfonation of nitrolignin with sodium hydrosulfite at pH = 8 for 6 hours at 85-93°C 1. At. In this case, nitro groups are reduced to amino groups, and sulfo groups are also introduced, which ensures the solubility of sunil in water. Sunil does not have significant advantages over nitrolignin, it is much more expensive, and therefore its use in industry has been limited.

An example of an effective technology would be the production of collactivite, an active adsorbent similar in its properties to active carbon grade B. The scheme for producing collactivite is shown in Fig. 1-3.

R
is. 1-3. Technological scheme for producing collactivite:

1– bunker; 2 – auger; 3 – dispenser scales; 4 – reactor; 5 – solenoid valve; 6 – time relay; 7 – oleum measuring stick; 8 – apparatus with a stirrer; 9 – pump; 10 – quartz filter; 11, 12, 14 – collections; 13 – ball mill; 15 – filter.

The TGL, dried to 18-20% humidity, is fed into hopper 1, from which auger 2, through a dosing scale 3, enters reactor 4. Oleum is also supplied here from measuring tank 7. Using an electromagnetic valve 5 and a time relay 6, the precise supply of oleum is regulated in relation to absolutely dry lignin. The temperature at the beginning of the reaction rises to 180 – 190 °C. From reactor 4, the mass enters the apparatus with stirrer 8, in which a cushion of 40–45% sulfuric acid is created from collection 11. Then the acidic collactivite suspension is fed by pump 9 to the quartz filter 10, where the product is washed with demineralized water until the acid content in the washing water is 0.2%. The washed collactivite suspension (20-25% suspended) is collected in collection 12, from where pump 9 is sent for grinding into ball mill 13 to a particle size of 10-100 microns and then into collection 14. The finished suspension is supplied to hydrolysis or xylitol shops, and, if necessary, to for filter 15.

Collaktivite is produced in the form of a suspension or paste containing 15–40% dry matter. Its yield according to specifications 59 – 80 – 75 is 70% by weight of THL. The main consumer of collactivite is the hydrolysis industry, where it is used for the purification of xylose syrups, as well as in those industries where product clarification is required.

Chlorolignin and lignophenol-formaldehyde resins are also obtained by chemical processing of THL. THL is not only easily nitrated, but also easily chlorinated at 20 °C with solutions of chlorine in CC1 4 and chlorine water. In this case, the resulting chlorine-lignin contains up to 30% chlorine.

Chlorlignin can be used with great success as a substitute for natural tanning agents, as an adsorbent for the extraction of certain rare earth substances from industrial waste - solutions. This use of chlorolignin, an accessible and cheap reagent, is very promising, since tannins are very scarce and expensive.

Chlorlignin can also be used as an active viscosity reducer for drilling fluids used for flushing wells and improving the condition of their walls. At appropriate dosages, chlorolignin can protect drilling fluids from coagulation by mineral salts. This property makes it a very valuable reagent when drilling in geological sections with formation waters of high mineralization. It can also be used as a flotation reagent in beneficiation practice during reverse flotation of heavy metal ores. In addition, chlor-lignin imparts biological and weather resistance to technical fabrics.

The scheme for the production of chlorolignin is shown in Fig. 1-4.

Fig.1-4. Technological scheme for the production of chlorolignin:

1– reactor; 2 – rotameter; 3 – bunker; 4 – auger; 5 – putsch filter; 6 – plywood drums.

The production of lignophenol-formaldehyde resins is based on the condensation of TGL with phenol. The resulting thermosetting resin is suitable for the production of press powders in the plastics industry. In its properties, it resembles phenol-formaldehyde resins of the novolac type. To harden it, 14% hexagon is introduced; the hardening process occurs at a temperature of 160 ° C and ends after 60-75 ° C.

The formation of new phenol-containing groups by condensation of lignin with phenol is explained by the opening of the cyclic benzyl ether structural elements of lignin. This is confirmed by the results of a study of the interaction of phenol with a model dimer - dehydrodiisoeugenol, when the opening of the coumaran ring takes place and the formation of a phenolic group:

In the first step, quinone meditate A is formed, which further reacts with phenol. Phenol can be added both in the o and in the - position, i.e., isomeric products are formed.

The method for producing lignophenol-formaldehyde resins was developed by Okun et al. In the proposed two-stage process in the presence of acid catalysts (TGL replaced 30-40% phenol), first the condensation of phenol and lignin occurs, and then the condensation of the resulting phenol lignin and formaldehyde. To obtain novolac resins, the amount of formaldehyde must be less than phenol. The generally accepted phenol:formaldehyde ratios are 1.1:1 and 1.3:1.

The use of a larger amount of formaldehyde than phenol in the presence of an acid catalyst leads to the formation of a resitol-type resin, which after some time loses its ability to melt and dissolve.

The physicochemical characteristics of the resulting resins meet the requirements of GOST for pulverbakelite.

To test the effect of phenol-formaldehyde resins on the strength of products made from press powders containing different amounts of technical lignin, standard parts were manufactured and subjected to standard mechanical tests (Table 1.3). The press powders had the following composition (parts by weight): novolac resin - 50, wood flour - 50, methenamine - 14, oleic acid - 3. The results of mechanical tests are given in table. 1.3.

From the data in table. 1.3 it follows that the mechanical properties of the studied lignophenol-formaldehyde resins are not inferior in performance to commercial resins, and therefore can be used in the production of conventional press powders.

Table 1.3. Mechanical properties of lignophenol-formaldehyde resins

1.2.2. Application of TGL as a filler

As mentioned above, TGL can be used as a filler for plastics instead of traditional ones - wood flour, soot, etc. For this, commercial hydrolytic lignin must have the following properties: moisture content up to 10%, ash content up to 5% and have granulometric uniformity (particle size approx. 150 µm). Lignin flour should have a slightly acidic or neutral reaction. The main areas of application of lignin flour: chemical industry (phenolic plastics), production of tires, rubber products, building materials (linoleum), etc.

One of the requirements for lignin flour is its low moisture content. Achieving such a moisture content of TGL before fine grinding presents a certain technological difficulty. It is more tempting to combine drying with grinding. However, this complex process does not always pay off when grinding high-moisture and plastic materials. Currently, a method of jet drying and grinding of TGL has been developed and is being used (Fig. 1-5).

Rice. 1-5.Technological scheme for the production of lignin flour:

1, 13, 15 – bunkers; 2 – belt conveyor; 3 – magnetic catchers; 4 – vibrating screen; 5 – conveyor for removing coarse lignin; 6 – conveyor; 7 – screw feeder; 8 – mixing chamber of the steam jet mill; 9 – separator; 10 – explosion valves; 11, 14 – cyclones; 12 – wet scrubber; 16 – feeder; 17 – packaging unit; 18 – scales; 19 – warehouse; 20 – scrubber pump; 21 – smoke exhauster; 22 – blower.

Wet lignin from the drain, after undergoing separation, is fed into a countercurrent jet mill, where it is captured on both sides by streams of superheated steam at a temperature of 400 °C and a pressure of 0.7 MPa. In the mixing chamber of the mill, when lignin flows collide, it is dried and crushed.

According to experimental data, consumption rates and energy costs for the production of 1 ton of lignin flour with a moisture content of 10% are relatively small and are: TGL (moisture content 65%) - 2.2 tons, superheated steam - 10 GJ, power electricity - 1.94 GJ, production water – 25.2 m3.

Lignin flour also meets the standards for wood flour in terms of dispersion. Thus, when replacing 30% of wood flour No. 180, 140 and 100 with flour from TGL in samples of grade 01-010-86, they satisfied the requirements of the relevant GOST in terms of physical and mechanical indicators.

According to NPO Karbolit, the demand for lignin flour in the country as a whole for use as fillers for 01-010-86 grade phenolics is 20 thousand tons with an annual effect of several million rubles. However, the use of the steam jet method is associated with the difficulty of feeding lignin into the screw feeder and rapid wear of the steam jet nozzles.

In order to improve the method and eliminate difficulties, research and pilot experiments were carried out at the Irkutsk Institute of National Economy (IINH) and a number of schemes were proposed.

In the first scheme, it was proposed to carry out direct screening of the required fraction of lignin flour, the amount of which, as shown above (see Table 1.2), with a particle size of less than 0.2 mm is 30 - 40%. The technological diagram (Fig. 1-6) included the following operations. TGL, after preliminary selection of fractions larger than 10 mm, was dried to a moisture content of 3–10%. The class less than 0.16 mm was then separated on sieve 016. The fraction of a class greater than 0.16 mm was sent either for re-crushing and again returned to the screen with a 0.16 sieve, or for briquetting or combustion of the original lignin in the furnace of the drying unit.

Next, the collected small class of TGL was supplied through the dosing hopper 5 for mixing into the runners 7, where press powder brand 03-010-02 (K-18-2) was supplied in a certain ratio through the dosing hopper 6. The process of plasticization - mixing in runners 7 lasted for 20 minutes. The finished press composition from hopper 8 was supplied for the manufacture of products. Three press compositions were tested, which included the following components:

Standard samples were made from these compositions under a pressing regime close to that adopted for the manufacture of parts from traditional materials: pressing pressure – 45.0 MPa, process temperature – 160 °C, holding time under pressure – 1.0 min/mm. Then the resulting samples were subjected to standard tests, the results of which are given in table. 1.4.

Table 1.4. Results of testing samples from press compositions

1 – drying unit; 2, 8 – bunkers for lignin and press composition, respectively; 3 – feeder; 4 – roar; 5, 6 – dosing hoppers for press powder and lignin, respectively; 7 – runners; 9 – press

Due to the addition of TGL to press powder grade 03-010-02 in the resulting press composition, the specific consumption of other components can be reduced (Table 1.5).

Table 1.5. Recipes of press powder brand 03-010-02 and press compositions [% (wt.)]

A significant reduction in the specific consumption of such expensive components as resin and wood flour due to the introduction of TGL reduces the total cost of the press material. Since press powder grade 03-010-02 is currently widely used for the manufacture of plastic products for household use, a decrease in its cost dramatically affects the profitability of enterprises.

The use of TGL expands the raw material base of press materials and increases the economic efficiency of production. With savings, as calculations show when saving 50 rubles per 1 ton of press compositions containing 20% ​​(wt.) TGL, the total economic effect on the entire volume of products made from press powder brand 03-010-02 will be several million rubles per year.

The second scheme, developed for the production of lignin flour, provides for a preliminary reduction in the moisture of the TGL until an easily mobile (free-flowing) state of lignin is achieved before loading into the screw conveyors of a steam jet mill. To reduce the cost of the drying process, an electroosmotic filter has been developed and tested, characterized by the simultaneous exposure of the dehydrated material to a constant electric field in the mode of osmotic effect, mechanical pressure and vacuum.

As a result of the tests, the optimal process parameters were determined: current density in the range of 0.02–0.05 A/cm2, pressing pressure 1.0–1.5 MPa. In this mode, the filtration speed increases by 3-5 times compared to purely mechanical dehydration, the humidity of TGL is reduced from 75-65 to 45-35% (wt). It has been established that the dehydration of hot TGL, taken directly from the pump after it has been “shot” from the hydrolysis apparatus, is more active than that of cooled TGL. The filter productivity, depending on the conditions, is 100-200 kg/(m2-h). Based on these results, a pilot plant was developed and built, which is a conveyor-type electroosmotic filter.

The tests carried out confirmed the promise of the new dehydration method. The efficiency of the electromechanical process is 2-3 times higher than the thermal process of lignin drying.

The IINH has carried out work to find more effective thermal methods for drying TGL, which can be used both at the first stage of lignin drying, for example, before feeding TGL into a steam jet or shaft mill, and at the second (final) stage of drying. This is how the process of lignin drying was studied in a vortex chamber developed by the Institute of Fossil Fuels (IGI) and in a vibration dryer at VNIIMT (VNII of Metallurgical Heat Engineering).

R
is. 1-7. Hardware diagram of a two-stage pilot plant for drying TGL:

1 – conveyor; 2 – roar; 3, 3a, 3b – screw feeders; 4, 4a – vortex chambers of the first and second stages; 5, 5a – cochleae of the peripheral stream; 6, 6a – cochleae of the central stream; 7, 7a – cyclones of the first and second stages; 8 – battery cyclone; 9 – hot gas blower; 10 – blower; 11 – firebox; 12 – roller press

For the first time in the practice of processing TGL, employees of the Institute of Inorganic Chemistry and IGI, under the leadership of P. Z. Shubeko, carried out experimental work on drying TGL at the stands of the Moscow Coke and Gas Plant. As a result of experimental studies, technological modes of deep drying were developed using one-stage and two-stage schemes and design recommendations were given for the construction of pilot and industrial installations for drying TGL in vortex chambers.

The diagram of a two-stage installation is shown in Fig. 1-7. The initial TGL from the conveyor 1 through the screen 2 is supplied to the screw feeder 3 with a ripper, and from there to the first stage of drying into the vortex chamber 4, where the coolant is used at a temperature of 600-700 ° C. The final drying of TGL is carried out in chamber 4a of the second stage. Part of the steam-gas mixture is pumped into the hot gas blower 9 for recirculation into the furnace 11, and part of it from the second stage cyclone 7a, after post-treatment in the battery of cyclones 8, is discharged into the atmosphere. The collected lignin dust is supplied for combustion in furnace 11, and the dried lignin is supplied for briquetting in press 12.

The consumption rate of lignin with an initial moisture content of 65% to produce drying material with a moisture content of 12%, taking into account the use of lignin dust, was 2.8–3.0 t/t. The specific gas consumption for drying 1 kg of initial TGL at a coolant temperature of 600°C is 2.8 m3/kg*, at 700°C - 2.3 m3/kg (gas volume is normalized to normal conditions). The consumption of dried lignin dust with a calorific value of approximately 23 MJ/kg and a furnace efficiency of 0.9 to obtain the coolant was 0.114 kg/kg of initial lignin.

The design studies carried out showed that when using a coolant at 700°C for an installation with a capacity of 2.3-2.7 t/h for drying at 12% humidity, vortex chambers with a diameter of 0.675 m and a length of 3.5 m (together with a volute) can be used ). Approximately capital costs for the construction of such a plant are 135 thousand rubles, and the cost of drying is about 3.5 rubles/t of drying material. With an increase in the productivity of the vortex chambers to 8 and even up to 16.6 t/h (for drying), their diameter mainly increases to 1.2 - 1.5 m (at 8 t/h) and to 1.8 - 2.0 m (at 16.6 t/h), and the length of the chambers remains constant and will be 2.5 - 3.0 m including snails. Specific capital costs for the construction of large industrial dryers of this type will decrease from 7 to 5 - 4 rubles/t of drying material, and the cost of drying to 2 rubles/t of drying material.

Table 1.6. Comparative technological indicators of vortex chambers

Rice. 1-8. Scheme of a bench vibrating drying installation:

1 – disc feeder; 2 – vibrating dryer; 3 – gas pipeline; 4 – flue gas pipeline; 5 – installation frame; 6 – combustion chamber.

In terms of drying parameters, main technological and technical-economic indicators, vortex chambers have a clear advantage over pneumatic gas dryers and shaft mills, as follows from the comparative data presented in Table. 1.6.

IINH, together with VNIIMT, conducted research and bench tests on drying TGL in vibration dryers, on the basis of which a plant was designed to produce 2 t/h of dry lignin. This installation has advantages over gas dryers in that it eliminates direct contact of finely dispersed highly reactive TGL with the coolant.

For the study, a pilot plant (Fig. 1-8) of the VNIIMT experimental plant was used, designed for high-temperature drying of various dispersed materials used in the metallurgical industry.

The vibration dryer (Fig. 1-9) is made in the form of a rectangular shaft measuring 150x120 mm, in which 180 pipes with a diameter of 20 mm and a wall thickness of 1.5 mm are arranged in a checkerboard pattern. There are 36 levels of height of the tube bundle, with three tubes in each. The transverse pitch of the pipes is 80, longitudinal - 20 mm. The height of the tube bundle is 1400 mm, the area of ​​the outer heating surface of one pipe is 0.961 m2. The shaft body and pipes are made of alloy steel 1Х18Н9Т.

Rice. 1-9. Vibration dryer:

1 – drying shaft; 2 – spring suspension; 3 – vibrator.

To remove steam generated during drying, the two side walls of the dryer shaft are made in the form of louvered grilles. The steam is collected in collectors located at the top of the dryer on both sides, and from there is released into the atmosphere. To provide controlled vibration, which not only intensifies the process, prevents particles from sticking together and forming lumps, but also increases heat transfer from the heated surface to the lignin layer, mechanical vibrators driven by a DC electric motor were used. To prevent the transmission of vibration to the installation frame, the shaft is suspended on four springs.

The drying agent - flue gases generated when natural gas is burned in the combustion chamber - passes inside the pipes, making six turns. The movement of flue gases and material is carried out according to a cross-counterflow pattern.

Wet lignin is fed into the feedstock hopper, then enters a vibrating dryer, where it is heated and dried. The dried TGL is sent to a closed receiver using a disc feeder with an adjustable rotation speed. To measure the temperatures of the material, gases and pipe walls of the vibrating dryer, chromel-alumel thermocouples are installed. In addition, the installation is equipped with control and measuring instruments for measuring the flow of air, flue gases, natural gas, vacuum in the air and smoke ducts, as well as determining the composition of gases. To measure the moisture content of the material passing through the mine unloading device, a Neutron-3 moisture meter was installed.

During the experiments, lignin with an initial moisture content of 60-65% was used. The average specific productivity of a vibrating dryer is 2 t/m3.

The determining operating parameter during the experiments was the temperature of the flue gases, which at the entrance to the vibrating dryer varied from 410 to 610°C. As tests have shown, at such a relatively high temperature of the heating gases, there were no deviations from the normal operation of the dryer, nor cases of lignin ignition. The temperature of the flue gases after the dryer ranged from 170 to 270°C, while the final moisture content of the lignin reached 22% at a heating temperature of 90-100°C. Based on the results of the experiments, the thermal technical parameters of lignin drying in a tubular vibration dryer were determined (Table 1.7).

Due to the low temperature of the flue gases leaving the dryer, heat losses are small and average 35.8%; while the thermal efficiency is 44.4%. As a result of processing the experimental data, the heat transfer coefficient from the flue gases to the material was calculated. It was quite high and averaged 47.22 W/(m2-°C). The dryer's intensity for evaporated moisture reached an average of 22 kg/(m2-h), or 817 kg/(m3-h), which indicates a relatively high efficiency of its operation. The rather high final moisture content of lignin (22%) is due to the small heating surface of the pipes and the insufficient residence time of the lignin in the drying shaft. The results of the studies showed the possibility of using a vibrating dryer for lignin dehydration and made it possible to provide initial data for the design of a pilot plant. Thus, VNII Energotsvetmet completed a technical design for a mine vibrating dryer, the characteristics of which are given below:

Unit productivity for dry lignin, 2

Lignin moisture content, %:

Initial 50-65

final 8-12

Coolant consumption - gas at norms, conventional, 8000

Vacuum, Pa (mm water column):

at the inlet to the dryer 147 (15)

at the exit from the dryer 3430 (350)

Lignin temperature before unloader, °C 100

Vibration amplitude, mm 0.3

Vibration work, Hz 20

In this drying unit, the process is carried out quite efficiently and with virtually no loss of lignin with exhaust gases. At the same time, there is no need for a cyclone system, the fire and explosion hazard of work is ensured, as well as the necessary sanitary and hygienic working conditions.

Table 1.7. Technical parameters of TGL drying in a vibrating dryer

1.2.3. Application of TGL in rubber production

The presence of active functional groups in technical lignin has led to interest in it as an active filler.

The work of various authors, in particular, employees of the Dnepropetrovsk Institute of Chemical Technology, has shown the possibility of using THL in highly dispersed form, as well as in the form of THL preparations containing chlorine and amino groups. The presence of these groups has a modifying effect on the properties of rubber-based rubbers. The greatest efficiency is typical for systems containing methylvinylpyridine and nitrile rubber and chlorolignin. Thus, when using 5 wt. shares of chlorolignin, 100 wt., shares of SKS-25 MVP-5 rubber, the modulus at 300% elongation increases by 17%, tensile strength increases by 16% at 25 ° C and by 30% at 100 ° WITH. The temperature resistance of rubber and its resistance to repeated deformation also increases significantly. Vulcanizates based on nitrile rubber SK.N-40, modified with chlorolignin, are superior in strength to control samples.

The use of TGL flour in the formulations of carcass rubbers for car tires in an amount of 3-5 wt., shares per 100 wt., shares of SK.I-3 rubber allows increasing their resources compared to serial ones by 10-15%.

The influence of hydrolytic lignin flour (HML) from various industries on the properties of rubbers for various purposes was also studied. It has been established that, regardless of the type of feedstock (wood or annual plants) and the method of processing wet coarse TGL into a dry powdery product, lignin flour exhibits the same modifying effect on the physical and mechanical properties of vulcanizates and corresponds to dry highly dispersed sulfate lignin.

Based on extensive laboratory and production tests of flour, it is recommended to use GLM in small quantities (5-15 wt., parts per 100 wt., shares of rubber) in rubber formulations for tires, rubber products and shoe bottoms instead of scarce and expensive ingredients (white soot, fibrous filler , lithopona, etc.).

Of particular interest is the use of GLM in tire production. The use of lignin flour as a modifying additive makes it possible to completely eliminate the highly deficient white soot of the BS-120 grade from the frame rubber formulation, provided that the product meets the developed technical requirements [% (wt.)]: moisture no more than 5.0, ash no more than 6; pH of the water extract - not less than 3.0; the remainder from sifting on sieve 01 K is no more than 0.02 (TU op. 59.022.32-85).

1.2.4. Application of TGL in the production of building materials

The literature describes various studies on the use of TGL for the production of building materials (thermal insulation, roofing and facing materials, brick, cement, expanded clay, etc.).

Back in the 50s, VNIIgidroliza developed a technology for producing porous slabs containing up to 55% TGL (on an absolutely dry basis) for heat and sound insulation of external walls, semi-solid slabs for indoor plastering and hard slabs for wall cladding.

A study was carried out of the thermal insulation properties of materials from TGL and its compositions with such binders as Portland cement, white-slurry cement, gypsum and lime. Three methods of using TGL have been proposed: as fill-in thermal insulation, as pressurized insulation and ligno-concrete structures. A mass composition for the manufacture of thermal insulation products has been proposed, consisting of 35-60% TGL, 15-35% polymer adobe paste and 15-30% expanded clay sand. The same authors proposed using TGL to produce thermal insulation material based on a bitumen binder, based on the fact that TGL contains a large number of active chemical groups that easily interact with bitumen, forming stable, oxidation-resistant bonds.

Research has been carried out in the field of manufacturing technology for composite pressed materials using TGL as an active additive to sawdust and plasticizer, for example, for flooring. A method for calculating the composition of compositions has also been developed, which makes it possible to control the quality of the press mixtures. The prospects for using TGL as an intensifier for clinker grinding in the production of Portland cement have been established. In this case, lignin has a plasticizing effect on the cement mortar. Its addition should be no more than 0.4% (per absolutely dry substance). Due to the air-entraining effect, TGL increases the frost resistance of cement. The widespread practical use of lignin in the cement industry is hampered by difficulties in transporting and dosing wet lignin into devices.

NYIMS (Minsk) has developed a technology for producing a new expanded clay material - agloporite, containing up to 20% TGL to the total mixture. "High dispersion, developed porosity and internal surface of TGL determine its uniform distribution in the charge, increase its gas permeability, increasing the rate of vertical sintering of the charge and productivity of sinter plants.

At the Leningrad Forestry Academy named after. S. M. Kirov conducted research on the production of fire-resistant composite board insulation containing TGL. The Ural Forestry Engineering Institute has studied the possibility of using TGL as part of phenol-formaldehyde binders in the manufacture of particle boards (chipboards). To obtain lignin phenol formaldehyde binders (LPF), TGL with a moisture content of 65% was used. Experiments have shown that boards based on LFF meet the requirements of the standard for P-3 chipboards, and are superior in water resistance to the best foreign samples.

1.2.5. Application of TGL for the production of anti-corrosion drugs

For the needs of the national economy, a huge amount of rust converter (PR), made from accessible and cheap raw materials, is required. As theoretical studies and practical experience have shown, TGL can serve as such a raw material. The theoretical prerequisite for the creation of PR based on hydrolytic lignin is its ability to form complex compounds with metals and, in particular, with iron oxides and its compounds. The purposefulness of the syntheses being carried out is associated with the modification of the lignin macromolecule, leading to an increase in the number of active functional groups and facilitating the introduction of amino groups.

Based on modified hydrolytic lignin, two types of rust converters have been developed and produced: PRL - liquid acid and PPR - powder of a basic nature. The PRL-2 rust converter, when applied to metal, acts as a converter not only of rust, but also of the soil on which protective paint and varnish coatings are applied. The transformation of rust into stable water-insoluble products occurs in approximately 24 hours. Long-term tests have shown that PRL-2 is an effective and cost-effective agent in the fight against corrosion. These drugs have found wide application in various sectors of the national economy and technology and have been introduced at more than 40 enterprises in the country. The economic effect of their use, depending on the complexity of the metal structure, is 5-7 thousand rubles. per 1 ton of drug.

1.2.6. Application of TGL in the production of medical products.

The high sorption properties of THL predetermined its use in medicine. Back in the 40s, a lignin preparation obtained by Scholler called Porlisan underwent successful clinical trials in the treatment of intestinal diseases.

At NPO "Gidrolizprom", the technology of porlizan was improved, a medical product was created, to which the nomenclature commission of the pharmacological committee of the USSR Ministry of Health assigned the name polyphepan. This drug has a high sorption capacity in relation to bacterial cells and the toxins they secrete, on the basis of which it was approved for the treatment of patients with diseases of the gastrointestinal tract, accompanied by dyspeptic disorders and general toxicity. Thus, 1 g of the drug adsorbs up to 7.3 million Escherichia coli bacteria, 1.9 million bacilli and 17.7 million cholera-like embryos. The process for producing polyphepane is based on alkaline treatment of TGL in order to purify it and increase its capacity. At the Institute of Wood Chemistry of the Academy of Sciences of the Latvian SSR, medicinal preparations “bilignins” were obtained based on TGL. They do not repeat polyphepan, as they adsorb bile acids and bettolipoproteins. The drugs were obtained by modifying THL with ammonia and amines. This made it possible to increase their adsorption capacity by 2 times compared to the activity of the original substance.

1.3. APPLICATION OF TGL IN AGRICULTURE

The studies established that lignin destruction products formed in the soil as a result of microbiological influence or applied as fertilizers play an active physiological role in the metabolism of plants and microorganisms. Under natural conditions, the described processes proceed at a low speed, and even lignin from plant residues begins to decompose only after a year and a half. Therefore, hydrolytic lignin that has undergone high-temperature acid condensation has increased resistance to these effects.

In this regard, it is necessary to carry out preliminary destruction of lignin to low molecular weight substances, which is accompanied by the formation of additional hydroxyl and carboxyl groups and will help increase the activity of lignin as a fertilizer. Work in this direction is very promising, as it will reduce the time required for humification and turn a burdensome industrial waste into a valuable commercial product, closing the cycle of lignin transformations in nature.

Currently, the following main directions for the use of lignin in agriculture have emerged: in its natural form, as a component of composts, in the form of modification products or destruction products.

For many years, extensive tests have been carried out on hydrolyzed lignin in its natural form as an organic fertilizer, which have shown that when it is applied from 7 to 30 t/ha (depending on the type of soil) under autumn cultivation, you can get some increase in yield, which, in in particular, for cotton it is 1.2-1.8 c/ha.

The positive effect of lignin is manifested in improving the physical properties of the soil and the conditions for the development of saprophytic fungi, creating a loose surface layer that ensures normal water-air exchange.

In many cases, lignin can be considered not only as a porous adsorbent, but also as a substance capable of forming complex compounds with many types of fertilizers. These properties are of particular importance in retaining nitrogen compounds in the soil, which are quickly washed out when using conventional mineral fertilizers.

According to data, in a mixture of THL with ammonia or urea, up to 25% of nitrogen is in the form of ammonium sulfate. The rest, according to the authors, is chemically associated with lignin. As hydrolytic lignin decomposes in the soil, chemically bound nitrogen transforms into an accessible form, which creates conditions for uniform nutrition of plants throughout the growing season.

Fertilizers based on hydrolytic lignin can be prepared by treating it with post-yeast mash. This achieves clarification of the mash and enrichment of lignin not only with organic substances, but also with nitrogen, phosphorus and potassium: (NPK) - 0.33%; P205 - 0.07%; K20 - 0.05%. Tests carried out over a number of years have shown that these fertilizers are not inferior in their effect to peat-mineral ammonium fertilizers and can serve as an additional source of organic substances.

According to N.V. Glushchenko, the use of hydrolytic lignin mixed with sludge from hydrolysis plants in an amount of 2.5 t/ha gave a 20% increase in yield.

More effective is the use of organo-mineral fertilizers obtained from partially decomposed hydrolytic lignin when composting it with mineral salts, manure and azobacter. At the same time, the validity period of mineral fertilizers increases and the positive effect is manifested not only in the year of application, but also in the next few years. According to Agrafuran, lignocellulosic fertilizers also increase the lifespan of soluble fertilizers.

For a number of years, the BSSR has been testing composts based on hydrolytic lignin and various substances (phosphorite flour, ammonium nitrate, potassium chloride) in ratios that depend on the tasks. After aging for 2-3 months. compost is treated with an aqueous solution of ammonia and applied to the soil, which increases the yield of potatoes by 84 c/ha and winter rye by 4.2 c/ha compared to the yield obtained by applying an equal amount of mineral fertilizers. When treated with a 25% aqueous solution of ammonia in hydrolytic lignin, from 1.5 to 6.6% of nitrogen is chemically bonded in ammonium, imine, amide, and amine forms.

Comparative studies of the physical properties of complex-mixed granular organic-mineral fertilizers in comparison with granulated complex-mixed three-component mineral fertilizers have shown that on loams, under the influence of equal amounts of water, 28% of nitrogen is washed out from the former and 19.2% less potassium oxide than from the latter. Therefore, the use of composts using hydrolytic lignin is more effective than the use of THL in its pure form.

An even greater effect was obtained when lignin was decomposed by white rot fungi before adding it to the soil, as well as its oxidative destruction with simultaneous enrichment of nitrogen and microelements. The use of ammonia and its derivatives as an alkaline agent during the oxidative decomposition (destruction) of lignin turned out to be especially fruitful.

Of significant interest is the development of new methods for producing nitrogen-containing lignin derivatives under milder conditions. A number of studies are devoted to the production of biologically active substances and fertilizers from lignin using nitrogen oxides, nitric acid, as well as nitrate extract from phosphorites as an oxidizing agent, followed by ammoniation. This results in a humus-like fertilizer rich in nitrogen and phosphorus. As a result of the deep oxidation of hydrolytic lignin with nitric acid, new biologically active substances were obtained - quinone nitropolycarboxylic acids.

The theoretical foundations of oxidation and production have been developed and the technological process for producing ammonium salts of these acids and lignostimulating fertilizer (LSU) has been implemented on a pilot industrial scale. The optimal application doses are 100-400 kg/ha, depending on the type of soil and crops. Long-term tests have shown the high efficiency of using LSU.

The experience of using lignin in agriculture shows that almost all types of substances used to increase yield can be obtained on its basis: fertilizers, stimulants, fungicides, structures, complexing agents, etc.

1.4. BRIQUETTING TGL

With the development of the hydrolysis industry, the problem of using lignin is becoming increasingly urgent. The lack of large-scale processing of lignin can lead to a retardation of the development of hydrolysis production. In addition, the costs of transporting lignin to dumps and their maintenance increase significantly.

The work of a number of authors has shown that a distinctive feature is the ability of lignin to transform into a viscoplastic state when exposed to high pressure - about 100 MPa. This circumstance contributed to the development of one of the promising areas of TGL processing - briquetting.

Research and pilot-industrial developments carried out by the IINH. In this case, the following briquetted ligno products can be obtained:

lignobriquettes to replace traditional carbon metallurgical reducing agents and lump charge in the production of crystalline silicon and ferroalloys;

smokeless fuel lignobriquettes;

briquetted lignin coal instead of wood in the chemical industry;

carbon sorbents from lignobriquettes for purification of industrial wastewater and extraction of heavy and noble metals;

energy briquettes from a mixture of lignin with coal screenings.

In recent years, about 35 thousand tons of lignobriquettes have been produced, which have found application in various areas of ferrous and non-ferrous metallurgy and are recommended for industrial production in accordance with TU 59-Sh-77. After testing these briquettes at the Chelyabinsk Electrometallurgical Plant, they were recommended as a carbonaceous reducing agent for the production of silicon ferroalloys.

As a result of research aimed at improving the briquetting process, a continuous high-pressure briquetting roller press was created (Fig. 1-10).

The installation includes the press itself 3 (Fig. 1-11), a press screw with drive 4, drive 2 for the press rolls, a hydraulic system for pressing the rolls with a hydraulic accumulator, an electrical unit with a thyristor rectifier unit and a control panel.

Rice. 1-10. High pressure briquetting roller press with flexible control of pressing parameters:

1 – roller drive electric motor; 2 – gearboxes; 3 – forming rollers; 4 – drive of the auger pre-presser; 5 – briquette conveyor

Rice. 1-11. Diagram of a high pressure briquetting roller press;

1 – lignin bunker; 2 – auger-prepressor; 3 – pressing rollers; 4 – conveyor; 5–press body; b – hydraulic pump.

A distinctive feature of the press is the ability to flexibly regulate all pressing parameters, which allows it to be used for briquetting dispersed materials with a wide range of physical and mechanical properties, for example, in waste processing shops of the microbiological and metallurgical industries, chemical and coal processing plants, etc.

Smooth control of the rate of deformation when compressing the material during the pressing period is ensured by using a direct current electric motor / to drive the forming rollers, the speed of which is regulated from the control panel.

A similar electric motor drives the auger-prepressor 4, which allows you to supply different amounts of material into the forming cells of the rolls 3 and thereby change the pressing pressure. In addition, this parameter is regulated by changing the force of pressing the rolls using hydraulic pump 6 (see Fig. 1-11). Using a hydraulic accumulator, you can move the rolls apart, which is especially important when large foreign inclusions get into the briquetted material, which prevents breakage of the press.

Another feature that facilitates the operation of the press is that the forming roll tires are assembled from separate segments. Cells are milled on these segments to form briquettes, the size and shape of which can be specified at the request of the consumer. Below are the technical characteristics of the press:

The estimated annual economic effect of the structure, according to the design institute, will be 108,538 rubles. compared to peat briquette press B-82-32.

1.4.2. TGL briquetting technology

The main parameters of the lignin briquetting process in order to obtain strong, binder-free, raw and pyrolyzed briquettes include pressing pressure and lignin humidity. It has been established that for THL of a certain humidity there is its own optimal pressure, which increases with decreasing moisture content. So, at a humidity of 24%, the optimal pressure is 100 MPa, and at a humidity of 15, 10 and 6%, it is 250, 350, 400 MPa, respectively. In Fig. 1-12 shows the dependence of the strength of briquettes on the moisture content of lignin at different pressing pressures. The maximum strength curve (dashed line) allows you to easily determine the pressure value corresponding to a given strength and select the lignin moisture content at a given pressing pressure in order to obtain the most durable briquettes.

It has been established that the pressing speed, particle size distribution, size, and chemical composition of the material do not have a significant effect on the strength of TGL briquettes. Moreover, the influence of these parameters is compensated by high pressing pressure (about 100 MPa), necessary to obtain durable briquettes.

The briquetting properties of lignin are highly dependent on temperature. By increasing the temperature of the dried lignin and the mold to 150°C, the plastic properties of lignin improve, which makes it possible to obtain strong and water-resistant briquettes without cracks at significantly lower pressing pressures than with “cold” briquetting. It was also found that the introduction of inert ore additives does not change the nature of the functional dependencies obtained during briquetting of lignin alone, but only slightly reduces the absolute strength indicators, which is within the tolerance. Thus, to obtain standard lignobriquettes, the following TGL briquetting parameters are optimal: pressing pressure 75-100 MPa, lignin humidity 8-12%, its size up to 5 mm, firing temperature 700 °C for ligno-coal briquettes and 350 °C for charge briquettes, rising speed firing temperature 2°C/min.

Rice. 1-12. Dependence of the strength of lignobriquettes on the humidity of TGL:

1 – pressing pressure 450 MPa; 2 – the same, 350 MPa; 3 – the same. 250 MPa; 4 – the same, 150 MPa; 5 – the same, 100 MPa; 6 – the same, 50 MPa; 7 – the same, 25 MPa.

Rice. 1-13. Technological diagram of TGL briquetting at the Mikhnevsky peat enterprise:

1 – raw material bunker; 2 – belt conveyor; 3 – furnace for obtaining coolant; 4 – loading auger; 5 – loading sleeve; 6 – hammer crusher; 7 – mine-mill dryer type MMT; 8, 9 – cyclones; 10 – dryer hopper; 11 – high pressure roller press; 12 – roar; 13 – fan.

The possibility of producing lignobriquettes under industrial conditions was tested using the example of sulfuric acid TGL and cellolignin from various enterprises. The first industrial trials and experiments were carried out using high-pressure stamp and roller presses.

The industrial scheme for lignin briquetting (Fig. 1-13) included an MMT 7 shaft-mill dryer with a dry lignin capacity of 2 t/h. Briquettes were made both from TGL alone and from a charge including TGL, quartz sand and iron ore concentrate. During the test, it was found that odubin cellolignin briquets more easily than sulfuric acid THL. Thus, the angular speed of rotation of the screw pre-presser and pressing rolls during briquetting of cellolignin was increased by 2.5 times; At the same time, the strength of the briquette was within the normal range.

In the manufacture of briquettes, two forms of cells in bandages were used. Using replaceable segments, briquettes of ovoid and lens-shaped shapes were obtained. The second form of briquettes, obtained in rivulet-toothed press bandages, is preferable. In this case, the briquettes are more durable and, with the same pressing mode, a smaller amount of non-briquetted fines is formed. The advantages of roller presses compared to stamp presses are higher productivity, lower metal consumption and specific energy consumption. In addition, the shape and size of briquettes produced on roller presses most fully satisfy the requirements of technological processing.

The production of lignin briquettes on an industrial scale was also organized in peat briquette factories. The pilot tests carried out made it possible to proceed to the production of lignobriquettes on an industrial scale at a peat enterprise equipped with a mine-mill dryer, stamp presses and other serial equipment, which confirmed the possibility of briquetting hydrolytic lignin at peat briquette plants. In this case, there is no need for any alterations of the technological equipment installed at the peat briquette plant, as well as restructuring of the technological process. The resulting briquettes were distinguished by high strength properties - abrasion resistance of 98% and shedding resistance of 97%.

Rice. 1-14. Technological scheme for the production of lignobriquettes at the Krasnodar BCP:

1 – expression; 2 – drying drum; 3 – dryer pipe; 4 – dry lignin hopper; 5 – coolant furnace; 6 – briquette stamp press

Industrial production of lignobriquettes is carried out according to the scheme shown in Fig. 1-14. Drying of lignin in a lignobriquette shop is carried out using a coolant obtained by burning dry lignin in a Shershnev furnace. The flue gases leaving the furnace at a temperature of 1000-100°C are cooled in the mixing chamber by atmospheric air and partially by exhaust gases entering the chamber through a recirculating gas pipeline. The initial drying temperature is 500-600 °C, the final temperature of the drying agent at the outlet of the system is 100-110 °C.

Crude lignin with a moisture content of 65-70% is dried in two stages in drying drum 2 (drum diameter 2.2 m, length 12 m) and in drying pipe 3 (diameter 650 mm, height 25 m), where drying occurs to the required humidity ( 12-38%).

The disadvantage of this technological process for drying lignin is the high thermal inertia of the drying drum.

When organizing TGL briquetting at hydrolysis plants, one should take into account the real possibilities of using the available coolant for drying lignin. For example, the presence of natural gas precludes the use of lignin to produce coolant. The high-parameter steam available at factories allows the use of steam-jet dryers, and the low-parameter steam allows the use of a pneumatic steam dryer (Fig. 1-15).

Rice. 1-15. Technological scheme for the production of briquettes from cellolignin using a pneumatic steam dryer:

1 – belt conveyor; 2, 5, 21 – bunkers; 3– dispenser; 4 – drum conveyor; 6 – screw; 7 – injector; 8 – heater; 9 – blower; 10 – pneumatic dryers; 11 – cyclone; 12 – gas pipeline; 13 – exhauster; 14 – refrigerator; 15- pipe; 16 – dispenser; 17 – storage hopper; 18 – vibrator; 19 – briquetting press; 20 – conveyor; 22 – carriage.

The greatest difficulty in organizing TGL briquetting technology is the fact that lignin from strains is characterized by continuously varying humidity ranging from 60 to 70%. In this regard, for stable drying it is necessary to use, as experience has shown, two-stage drying. However, using a high-inertia drum dryer in the first stage is erroneous.

Currently, a two-stage TGL drying scheme is in use using the first stage of a pipe-dryer, and the second - a mine-mill dryer (Fig. 1-16). The experience of recent years has shown the stability of the operation of such a scheme with the production of dryers with 12-18% humidity. In addition, the dryer pipe provides stable humidity with variable humidity of the initial TGL and effectively acts as a separator, where lignin is cleaned of large foreign inclusions missed by the magnetic trap.

1.4.3. Briquetting of TGL with special additives for metallurgy

The technological scheme for pressing charge briquettes for smelting ferroalloys (Fig. 1-17) was developed by the IINH jointly with the Dnepropetrovsk Metallurgical Institute, the Kharkov Giprostal Institute and the Kuznetsk Ferroalloy Plant.

Hydrolyzed lignin with an initial moisture content of 65–67% is unloaded from hopper 1 by feeder 2 onto belt conveyor 3, which delivers it to the system of drying units of the vortex chamber type 4 and 5 (first and second stages, respectively) of the IGI design or to a mine-mill dryer of the MMT type. The lignin, dried to a moisture content of 8-12%, enters the cyclone 6, where it settles and is fed by the feeder-doser 7 into the mixer hopper 8.

Rice. 1-16. Technological diagram of the lignobriquette section of the Astrakhan State Plant:

1–tonka; 2–pipe-dryer; 3, 5 – cyclones: 4 – mine-mill dryer; 6 – magnetic separator; 7 – belt conveyor; 8, 11 – lignin bins; 9 – screw feeder; 10 – screw conveyor; 12 – roller press; 13 – smoke exhauster; 14 – gate; 15 – wet scrubber; 16, 18 – belt conveyors; 17 – sieve; 19 – bunker warehouse.

Sand and iron ore concentrate (IOC) - ore components of the charge - from receiving bins 9 of raw sand and iron ore concentrate by feeders 10 are loaded into drying devices 11, from where they are sent to screens 12. After screening, the over-screen product is supplied for crushing to runners 13, and fine fractions - in bunkers 14 dry sand and iron ore concentrate. Large components crushed in the runners also go there. The unloading of sand and iron ore concentrate from the bunkers, their dosage in a given ratio and supply to the mixer is carried out by dosing feeders 15. The batch prepared in the mixer 8 enters the batch hopper 16 of a high-pressure roller briquette press 17 with a pre-presser, where the batch is briquetted under a pressure of 100-120 MPa.

Rice. 1-17. Technological scheme for the production of charge lignobriquettes for smelting ferroalloys:

1, 7. 11–14, 16, 18, 20 – bunkers; 2 – feeder; 3 – belt conveyor; 4 – magnetic separator; 5 – mine-mill dryer; c – cyclone; 8 – drying drum; 9 – roar; 10 – grinding runners; 15 - mixer; 17 – “Volna” type press; 19 – vertical continuously operating retort; 21 – electric furnace.

The briquettes are sent through a screen 18 to the briquette hopper 19. The screenings are ground by runners 20 and fed back into the mixer. The finished briquettes from the hopper 19 are sent to the ore-thermal furnace 21.

Compliance with the necessary regimes of individual stages of the technological process ensures the production of durable heat-resistant briquettes that can withstand compression of more than 7.5 MPa.

Joint briquetting of agglomerated charges with TGL significantly improves the process and economics of ferroalloy production. Melting 75% ferrosilicon in a 1200 kV-A furnace showed that energy savings amounted to 27.3%, and furnace productivity increased by 32.7% compared to existing performance on a traditional bulk charge.

Lignon briquettes and briquetted lignin ore charges can be widely used in the smelting of high-silicon ferroalloys, silicocalcium and master alloys with rare earth additives. This has been confirmed by industrial tests in various metallurgical processes at leading enterprises of the USSR Ministry of Ferrous Metallurgy, where more than 30 thousand tons of lignobriquettes were used instead of carbonaceous reducing agents.

When using lignobriquettes, the electric smelting process is significantly improved; self-discharge of the charge is observed, the seating of the electrodes is deepened, the reaction zone of the furnace is expanded, and manual screwing of the furnace is eliminated. All this indicates that lignobriquettes act as a high-quality ripper-regenerator.

Considering that lignobriquettes, in addition to a reducing agent, are also rippers, which is very important in the ore-thermal processing of silicon, a technology for producing a complex carbonaceous reducing agent by briquetting TGL in a mixture with petcoke screenings has been developed at the IINH. Such a briquetted complex reducing agent can also replace coke and charcoal in the smelting of high-silicon ferrosilicon.

The advantage of this reducing agent is that the addition of petcoke reduces the ash content to 1.0-1.5% and increases the solid carbon content to 60-70%. Thus, without the use of pyrolysis in lignobriquettes, the standards of charcoal in terms of ash and carbon are achieved. The strength of briquettes, characterized by a specific compressive resistance of 10-15 MPa, is an order of magnitude higher than charcoal. This eliminates the labor-intensive thermal operation and preserves the ability of the briquettes to shrink, which ensures loosening of the top and self-discharge of the charge into the reaction zone of the furnace. As a result, the technical and economic indicators of the ore-thermal process are improved and the quality of the smelted metal increases. In addition, the briquetted complex reducing agent expands the raw material base of carbonaceous reducing agents in metallurgy.

The possibility of replacing scarce and expensive charcoal with cellolignin briquettes in the smelting of crystalline silicon has also been shown. Even replacing 25% of charcoal with briquettes revealed great prospects for the use of this new reducing agent. Such basic indicators of furnace operation as productivity, consumption of quartzite and electricity remained at the same level. The specific consumption of charcoal and petcoke has decreased significantly.

1.4.4. Lignocoal production

The technology for producing lignin coal from briquetted hydrolytic lignin, developed by the Institute of Inorganic Chemistry, includes drying, briquetting of TGL and pyrolysis of lignobriquettes (Fig. 1-18). Lignocarbon briquettes replace, as shown by the work of the Institute of Chemical Engineering, acutely scarce charcoal, and can be used in ferrous and non-ferrous metallurgy in the smelting of special steels and crystalline silicon, in the production of carbon disulfide and as raw coal for the production of carbon sorbents.

The production of lignocoal from briquettes will expand the raw material base for the production of charcoal, linking it to hydrolysis plants with a year-round supply of raw materials. In addition, the proposed redistribution will allow for deeper processing of wood raw materials, additionally obtaining such valuable chemical products as pyrocatechin, high-calorie gas, etc. from the pyrolysis of briquettes.

Rice. 1-18. Scheme for the production of coal from lignobriquettes:

1 – firebox; 2 – drying; 3 – briquetting press; 4 – ring pyrolysis furnace; 5 – coal bunker.

The production of coal and lignobriquettes is not difficult. In order to study the prospects for using pyrolysis furnaces of various designs, thermolysis of briquettes was carried out under different conditions: at high temperatures up to 900°C - in a ring furnace designed by the Moscow Chemical Technology Institute and in a chamber furnace at the pilot plant of the Kuznetsk branch of VUKHIN; at an average temperature of 450 - 550 ° C - in industrial horizontal chamber furnaces designed by the Sverdlovlesprom Production Association and in a vertical experimental retort of the TsNILHI (Central Scientific Research Forest Chemical Institute).

In all pilot-industrial experiments, it was found that lignobriquettes successfully replace the traditional source fuel - wood. Moreover, in all cases, the technological regime was characterized by stability and increased productivity. The quality of lignobriquettes was close to charcoal from birch wood.

In chamber furnaces and in a vertical retort, productivity increased by 2.0 - 2.5 times. This is explained by the fact that the drying stage is practically excluded from the pyrolysis cycle, since the moisture content of briquettes is 12–15% compared to 60–65% for wood raw materials. In addition, lignobriquettes have a large bulk mass.

With the cost of lignocarbon briquettes being 120 rubles, the economic effect will be 60 – 70 rubles/t of the finished product. Just one hydrolysis plant, with a lignin yield of 65% in the amount of 120 thousand tons, can produce 40 thousand tons of coal and receive, depending on the type of coal produced, from 2.8 to 4.0 million rubles. economic effect per year.

Subject to a mild pyrolysis regime, which is possible in all of these furnaces, lump lignin coal can be obtained from briquetted lignin, which has high strength (compression resistance up to 10.0–13.0 MPa), porosity (up to 45–55%), heat resistance (20 – 30 MPa at 800 °C) and high electrical resistance. The coal yield during pyrolysis of lignobriquettes is 40 - 45%, the solid carbon content is 85 - 90%, the resin yield is on average 14%, the phenol content in the resin is 50 - 55% (pyrocatechol - 14 - 16%), the gas yield is on average 15% at calorific value 20950 – 25140 kJ/m3. All this indicates the technological efficiency of the process - the yield of carbonaceous material is quite high, the resin can serve as a raw material for the production of an antioxidant, and gas and liquid pyrolysis products can serve as a coolant for heating briquettes.

In table Table 1.8 shows the comparative physicochemical properties of pyrolyzed lignobriquettes, charcoal and coal coke.

Table 1.8. Properties of pyrolyzed lignobriquettes and other reducing agents

* At P = 196 kPa.

** In the numerator - oxide content, %. The denominator is the same per 100 kg of carbon, kg

Comparison of the characteristics of semi-coke and coke obtained from lignin with charcoal indicates the similarity of their physicochemical properties. The closest characteristics are the average temperature yield of volatile substances, ash content and elemental composition (except sulfur), reactivity and resistivity.

The advantage of cocolignin is its increased structural strength (41-45%), while low mechanical strength is one of the main disadvantages of charcoal as a carbonaceous reducing agent.

Rice. 1-19. Scheme for the production of coke from hydrolytic lignin:

1, 6, 11 – bunkers; 2 – feeder; 3 – conveyor; 4 – vortex chamber; 5 – cyclone; 7 – roller press; 8 – roar; 9 – semi-coking furnace; 10 – ring furnace; 12 – cooling conveyor; 13 – carriage.

As a result of the research, a basic scheme for producing coke from hydrolytic lignin was developed (Fig. 1-19). Wet lignin (60–70%) from hopper 1 by feeder 2 and conveyor 3 with a magnetic separator is fed into a shaft-mill dryer or vortex chamber 4, where it is dried to a moisture content of 10–20%, and then it settles in cyclone 5. From the hopper 6 dry lignin at 40–60 °C is sent for briquetting to a high-pressure roller press 7 with a pre-presser. The finished briquettes are sent to screen 8. Spills, crumbs and broken briquettes are returned to hopper 6 using a conveyor.

Raw briquettes are sent to a continuously operating furnace (vertical retort, semi-coking furnace 9 or ring furnace 10), where they are heated in a given mode. After this, the briquettes are subjected to dry extinguishing in hopper 11, from where they are sent to the consumer via cooler conveyor 12 in car 13.

The metallurgical suitability of lignocarbon briquettes was assessed in the process of smelting ferrosilicon from a lump charge, and in which lignin coal was used instead of metallurgical coke. A noticeable improvement in the performance of the furnace top was noted. The diameter of the working surface of the furnace has increased (by 50 - 70 mm) and its gas permeability has increased significantly. The charge settled easily, the current load was more uniform.

A comparative analysis of experimental smelting of ferroalloys using raw and coked lignobriquettes and nut coke, carried out at a ferroalloy plant in a furnace with a capacity of 230 kV*A, showed that the best technological and technical-economic results were obtained using coke-lignin. The use of lignobriquettes, in comparison with coke, made it possible to increase the voltage on the low side of the furnace by 12%. In the best series of experiments, the specific energy consumption when using coke briquettes and raw briquettes decreased by 13.1 and 6.3%, respectively, compared to coke nuts.

1.4.5. Preparation of active carbons from lignobriquettes

The demand for activated carbons (AC) is steadily increasing, but their quantity does not satisfy the demand. Industrial ACs are very expensive. Activated carbons are of particular interest for the sorption extraction of noble metals. This process has a number of advantages compared to ion exchange technology and gold deposition with zinc dust.

IINH together with the Institute of Rare Metals (Irkutsk) have developed a technology for producing carbon sorbents from briquetted TGL. The production scheme includes drying of TGL, its briquetting, pyrolysis of briquettes and their activation. The resulting coal is close in its properties to AC type IGI-S. Activated carbon from TGL has a sorption activity for iodine of up to 115.7%, a total specific porosity of up to 0.83 cm3/g, and a specific surface of 1200 – 1260 mg/t.

Research has shown that high-temperature pyrolysis (up to 900°C) can produce highly active carbon sorbents without an activation step. Such sorbents have high structural strength, which according to GOST 16188 - 70 is 80 - 83%. However, the absence of an activation stage slightly reduces the pore volume to 0.25 - 0.45 cm3/g, but this strength is sufficient for sorption from solutions of various types.

Activated carbons from lignin-carbon briquettes, obtained without activation, were tested in industrial columns for the sorption of noble metals from cyanide industrial wastewater. When the gold content in the solution was 0.035 mg/l, its recovery was 93%. Characterized by its low cost, the TGL sorbent is very promising for industrial use.

Their properties correspond to reinforcement, and lignin, which has high compressive strength, corresponds to concrete.

From a chemical point of view, lignin is the aromatic part of wood. Deciduous wood contains 18-24% lignin, coniferous wood - 27-30%. In wood analysis, lignin is considered as the non-hydrolysable part of wood.

Lignin, unlike carbohydrates, is not an individual substance, but is a mixture of aromatic polymers of related structure. That is why it is impossible to write its structural formula. At the same time, it is known what structural units it consists of and what types of bonds these units are combined into a macromolecule. The monomer units of the lignin macromolecule are called phenylpropane units (PPU), since these structural units are derivatives of phenylpropane. Coniferous lignin consists almost entirely of guaiacylpropane structural units. In addition to guaiacylpropane units, the composition of leaf lignin contains large quantities of syringylpropane units. Some lignins, mainly from herbaceous plants, contain units that do not contain methoxy groups - hydroxyphenylpropane units.

Lignin is a valuable chemical raw material used in many industries and in medicine.

Fire properties

Fire properties: Combustible powder. Self-ignition temperature: airgel 300 °C, air suspension 450 °C; lower concentration limit of flame propagation 40 g/m3; maximum explosion pressure 710 kPa; maximum rate of pressure rise 35 MPa/s; minimum ignition energy 20 mJ; minimum explosive oxygen content 17% vol.

Extinguishing media: Sprayed water, air-mechanical foam.

Attempts were made to extinguish burning lignin at the landfill by pumping clay solution into drilled wells.

To extinguish lignin, sludge (thermal power plant waste) is sprayed into the landfill using hydropulp and penetrates into the surface layer of lignin to a depth of 30 cm. Thanks to the mineral component, they prevent the occurrence of fires. In place of landfills that have been lifeless for many years, smoking, this spring, grass can be planted.

Application

Sulfate lignin is used to a limited extent in the production of polymeric materials, phenol-formaldehyde resins, and as a component of adhesive compositions in the production of chipboard, cardboard, plywood, etc. Hydrolytic lignin serves as boiler fuel in wood chemical industries, as well as raw materials for the production of granular activated carbon, porous bricks, fertilizers, acetic and oxalic acids, fillers.

More recently, lignin has been successfully used in the production of polyurethane foam.

In 1998, in Germany, Teknaro developed a process for producing Arboform, a material called “liquid wood”. In 2000, a plant for the production of bioplastics was opened near Karlsruhe, the raw materials for which are lignin, flax or hemp fibers and some additives, also of plant origin. In its external form, arboform in a frozen state is similar to plastic, but has the properties of polished wood. The advantage of “liquid wood” is the possibility of its repeated processing by melting. The results of the analysis of arboform after ten cycles showed that its parameters and properties remained the same.

Activated by alkaline treatment followed by washing and neutralization, lignin is used to collect oil and petroleum product spills from water and solid surfaces.

In medicine, hydrolytic lignin is registered as an international nonproprietary name and is used as a medicine (Poliphan, Polyphepan, Polyphepan granules, Polyphepan paste, dietary supplement Polyphepan plus, Lignosorb, Entegnin, Filtrum-STI, Laktofiltrum) Enterosorbent based on a natural polymer of plant origin lignin was developed in Germany by G. Scholler, L. Meyer and R. Brown in 1943 under the name “porlisan”. Lignin was successfully used against diarrhea of ​​various origins, and was administered to young children by enema. In 1971, “medical lignin” was created in Leningrad, which was later renamed Polyphepan. . Tests conducted on frogs and rabbits did not reveal any signs of toxic effects of the drug. P. I. Kashkin and O. D. Vasiliev in the same year studied the adsorbing ability of lignin and showed that 1 g of the drug absorbs and retains 7,300,000 bacteria in its structure. The absorption of lignin by salmonella, cholera-like vibrio, yellow staphylococcus and some fungi also turned out to be very high.

Hydrolyzed lignin is also used in veterinary medicine for the same purposes as in humans.

Lignin-based enterosorbents have enterosorbent, detoxification, antidiarrheal, antioxidant, hypolipidemic and complexing effects. Binds various microorganisms, their metabolic products, toxins of exogenous and endogenous nature, allergens, xenobiotics, heavy metals, radioactive isotopes, ammonia, divalent cations and promotes their excretion through the gastrointestinal tract.

Application of enterosobrents based on hydrolytic lignin

Lignin is one of the main components responsible for the vanilla aroma of old books. Lignin, like wood cellulose, decomposes over time, under the influence of oxidative processes, and emits a pleasant odor.

Notes

1. Maderas. Ciencia y tecnología - MECHANICALLY-INDUCED WOOD WELDING
2. ScienceDirect - Current Biology: Discovery of Lignin in Seaweed Reveals Convergent Evolution of Cell-Wall Architecture
3. "Lignin", TSB
4. Lignin hydrolytic; Polyfan; Polyphepan; Polyphepane granules; Filtrum-STI; Entegnin; Entegnin-N. (Russian) . AMT - a directory of medications. Archived from the original on August 23, 2011. Retrieved February 1, 2010.
5. A. Ya. Korolchenko, D. A. Korolchenko. Fire and explosion hazard of substances and materials and means of extinguishing them. Directory: in 2 parts - M.: Ase. “Pozhnauka”, 2004. Part 2. p.28
6. New technology will be used to extinguish lignin in the Irkutsk region| elimination of man-made disasters| WASTE RECYCLING
7. Irkutskenergo
8. Bulletin of the Irkutsk Scientific Center SB RAS. Issue 31
9. Lignin - Chemical Encyclopedia
10. Green plastic produced from biojoule material BioJoule Technologies Press Release, 12 July 2007.
11. TECNARO GmbH - official website
12. Arboform - liquid wood
13. Liquid wood instead of plastic
14. http://www.regmed.ru/SearchResults.asp
15. Polyphepan
16. Fitos - Publications. Project Fitos Issue 1
17. Articles for doctors about Polyphepan
18. Polyphepan is the most effective remedy for diarrhea (diarrhea), used in the treatment of diarrhea in pregnant women and adults.
19. The company Saytek is a manufacturer of enterosorbent Polyphepan. An effective remedy for diarrhea (diarrhea), humic fertilizers
20. Search the drug database, search options: INN - Hydrolytic lignin, flags - "Search TKFS" . Circulation of medicines. Federal State Institution “Scientific Center for Expertise of Medical Products” of Roszdravnadzor of the Russian Federation (11/26/2009). - A standard clinical and pharmacological article is a by-law and is not protected by copyright in accordance with part four of the Civil Code of the Russian Federation No. 230-FZ of December 18, 2006.

Hydrolyzed lignin - an excellent high-calorie fuel and easily accessible renewable raw material for the production of fuel pellets and briquettes.

Currently, the relevance of the issue of producing alternative energy sources is constantly increasing. There are a number of reasons for this.

1. Traditional energy resources - gas, coal, oil - are becoming more and more difficult to extract every year, and this leads to a constant increase in their cost. As is known, the issue of the cost of imported gas is of particular relevance for Ukraine.

2. Reserves of traditional energy resources are rapidly depleting, which makes the production of alternative energy resources a very promising business area.

3. The production of alternative energy sources is stimulated by the Governments of all developed countries, including Ukraine.

Lignin Lignin storage facility is on fire

Lignin pellets Pini&Key lignin briquettes

The main competition in this industry does not lie in sales- there are no problems with it, and, basically, all products are shipped for export to the countries of the European Union - and in the field of providing raw materials. The fact is that many enterprises that have installed briquetting or biomass granulation equipment are currently not operating at full capacity, and are often completely idle due to lack of raw materials. This is primarily due to the seasonality of the availability of certain types of raw materials (sunflower husks, straw, cereal crop waste, corn processing waste, other types of agricultural raw materials), incorrect choice of equipment installation location (for example, distance from potential sources of raw materials), high logistics costs for the delivery of raw materials , which, as a rule, has a very low bulk weight (for example, the bulk weight of sunflower husks is 100 kg/m3).

In such a situation, lignin is a good alternative to agricultural waste as a raw material, since its reserves are available in sufficiently large quantities regardless of the processing season, lignin lends itself well to granulation and briquetting due to its excellent binding properties, and has a fairly large bulk weight (up to 700 kg/m3) , which makes it profitable to transport it over considerable distances even not in granular form, has a good calorific value comparable to coal, with a much lower ash content, and the price of the raw material, lignin, is relatively low. Due to the special properties of lignin, in the technology of its preparation for further use, special importance is attached to the issue of drying lignin.

If consider lignin from a physicochemical point of view, then in its original form this substance is a complex sawdust-like mass, the moisture content of which reaches up to seventy percent. In fact, lignin is a unique complex of substances that consists of polysaccharides, a special group of substances belonging to the so-called lignohumic complex, monosaccharides, various mineral and organic acids of varying saturation, as well as a certain part of ash. Hydrolyzed lignin is a sawdust-like mass with a moisture content of approximately 55-70%. In terms of its composition, it is a complex of substances, which includes the lignin of the plant cell itself, part of the polysaccharides, a group of substances of the lignohumic complex, mineral and organic acids not washed after hydrolysis of the monosaccharide, ash and other substances. The content of lignin itself in lignin ranges from 40-88%, polysaccharides from 13 to 45%, resinous substances and lignohumic complex substances from 5 to 19%, and ash elements from 0.5 to 10%. The ash of hydrolysis lignin is mainly alluvial. Hydrolytic lignin is characterized by a large pore volume approaching the porosity of charcoal, high reactivity compared to traditional carbonaceous reducing agents and twice the solid carbon content compared to wood, reaching 30%, that is, almost half the carbon of charcoal.

Hydrolytic lignin is distinguished by its ability to transform into a viscoplastic state when pressure of about 100 MPa is applied. This circumstance predetermined one of the promising directions for using hydrolytic lignin in the form of briquetted material. It has been established that lignobriquettes are a high-calorie, low-smoke household fuel, a high-quality reducing agent in ferrous and non-ferrous metallurgy, replacing coke, semi-coke and charcoal, and can also be used for the production of coal such as charcoal and carbon sorbents. Research and experimental work of a number of organizations have shown that o briquetted hydrolytic lignin can be a valuable raw material for the metallurgical, energy and chemical sectors of the country's national economy, as well as high-grade municipal fuel.

Technological developments that make it possible to obtain the following briquetted ligno products can be recommended for implementation:
- lignobriquettes to replace traditional carbon metallurgical reducing agents and lump charge in the production of crystalline silicon and ferroalloys;
- low-smoke fuel lignobriquettes;
- briquetted lignin coal instead of wood in the chemical industry;
- carbon sorbents from lignobriquettes for purification of industrial wastewater and sorption of heavy and noble metals;
- energy briquettes from a mixture with coal screenings.

Lignin fuel briquettes are high-quality fuel with a calorific value of up to 5500 kcal/kg and low ash content. When burned, lignin briquettes burn with a colorless flame without emitting a smoky smoke plume. The density of lignin is 1.25 - 1.4 g/cm3. The refractive index is 1.6.

Hydrolyzed lignin has a calorific value, which for absolutely dry lignin is 5500-6500 kcal/kg for a product with 18-25% moisture content, 4400-4800 kcal/kg for lignin with 65% moisture content, 1500-1650 kcal/kg for lignin with a moisture content of more than 65%. According to its physicochemical characteristics, lignin is a three-phase polydisperse system with particle sizes ranging from several millimeters to microns or less. Studies of lignins obtained at various plants have shown that their composition is characterized on average by the following content of fractions: with a size greater than 250 microns - 54-80%, with a size less than 250 microns - 17-46%, and with a size less than 1 micron - 0.2- 4.3%. In structure, a particle of hydrolytic lignin is not a dense body, but is a developed system of micro- and macropores; the size of its internal surface is determined by humidity (for wet lignin it is 760-790 m2/g, and for dry lignin only 6 m2/g).

As shown by many years of research and industrial testing carried out by a number of research, educational and industrial enterprises, valuable types of industrial products can be obtained from hydrolytic lignin. For the energy sector, briquetted municipal and fireplace fuel can be produced from the original hydrolyzed lignin, and briquetted energy fuel can be produced from a mixture of lignin with coal enrichment screenings.

The process of lignin combustion in technological furnaces without direct heat transfer has significant differences compared to the furnaces of steam boilers. They do not have a beam-receiving surface, and therefore, in order to avoid slagging of ash, it is necessary to carefully calculate the aerodynamic modes of the process. The temperature of the flame core, due to the lack of direct heat transfer, turns out to be higher and is concentrated in a smaller volume than in the furnaces of steam boilers. To burn lignin, it is most advisable to use a flare furnace of the Shershnev system, which provides sufficiently high efficiency for fuels with a high degree of dispersion.

Lignin can be effectively used as fuel for combustion in a heat generator of a drying complex for drying sawdust or other biomass in lines for the production of fuel granules, pellets and fuel briquettes. Carefully prepared pulverized fuel is close to liquid fuel in terms of burnout rate and combustion completeness. Complete combustion in a torch is ensured with a lower excess air ratio and, consequently, with a higher temperature. When conducting the combustion process with a small excess of air, explosion-proof operating conditions for the drying complex are ensured, which positively distinguishes drying with the direct use of flue gases from the drying method with heated air.

Thus, lignin is an excellent, high-calorie fuel and an easily accessible renewable raw material for the production of fuel pellets and briquettes.

Application of powdered lignin.

Powdered lignin is suitable as an active additive in road asphalt concrete, as well as for adding fuel oil when used in energy and metallurgy. Hydrolyzed lignin, used as a mineral powder, allows:
1. To increase the quality of asphalt concrete (strength - by 25%, water resistance - by 12%, crack resistance (fragility) - from -14°C to -25°C) through additional modification of petroleum bitumen.
2. Save road construction materials: a) petroleum bitumen by 15-20%; b) lime mineral powder 100%.
3. Significantly improve the environmental situation in the waste storage area.
4. Return fertile lands currently occupied by dumps.

Thus, studies conducted on the use of technological hydrolytic lignin (THL) in the production of asphalt concrete show that there are opportunities to significantly expand the raw material base of materials for the construction of modern roads (republican, regional and urban), while simultaneously improving the quality of their coating by modifying petroleum bitumen with hydrolytic lignin and complete replacement of expensive mineral powders.

Posted 06/01/2010

Origin and production of lignin

Lignin from lat. lignum- wood, - a complex (network) aromatic natural polymer that is part of terrestrial plants, a product of biosynthesis. After cellulose, lignin is the most abundant polymer on earth and plays an important role in the natural carbon cycle. The emergence of lignin occurred during the evolution of plants during the transition from an aquatic to a terrestrial lifestyle to ensure rigidity and stability of stems and trunks (similar to chitin in arthropods).

In English and German, lignin is lignin, less commonly lignen or lignine.

As is known, plant tissue consists mainly of cellulose, hemicellulose and lignin. Coniferous wood contains 23-38% lignin, deciduous wood - 14-25%, and cereal straw - 12-20% by weight. Lignin is located in the cell walls and intercellular space of plants and holds cellulose fibers together.

Together with hemicelluloses, it determines the mechanical strength of trunks and stems. Lignin ensures the tightness of cell walls (for water and nutrients) and, thanks to the dyes it contains, determines the color of lignified tissue.

Lignin is firmly physically and chemically incorporated into the structure of plant tissue, and its effective isolation from there by industrial methods represents a very complex engineering problem.

It is customary to distinguish between protolignin, lignin contained inside the plant in its natural form, and its technical forms obtained by extraction from plant tissue using various physicochemical methods. Lignin is not specially produced; it and its chemically modified forms are waste from biochemical production. During the physicochemical processing of plant tissue, the molecular weight of lignin decreases several times, and its chemical activity increases.

In the hydrolysis industry, powder so-called is obtained. hydrolytic lignin.

In pulp production, water-soluble forms of lignin are formed. There are two main pulping technologies, the more common kraft (alkaline) pulping and the less commonly used sulfite (acid) pulping.

Lignin obtained in sulfate production, the so-called. sulfate lignin is largely utilized in power plants of pulp mills.

In sulfite production, solutions of sulfite lignins (lignosulfonates) are formed, some of which accumulate in lignostorages, and some go with the wastewater of the enterprise into rivers and lakes.

In English literature there are also:

Sulfur-free lignin (hydrolytic lignin);

Sulfur lignin - sulfur lignin (i.e. lignin from cellulose production).

To one degree or another, the recycling of lignin is carried out by the enterprises producing it themselves, but hydrolytic lignin, sulfate lignin and lignosulfonates are also present on the market as commercial products. There are no international or Russian standards for technical lignins and they are supplied according to different factory specifications.

Formula and chemical properties of lignin

In the chemical sense, lignin is a conditional and generalizing concept. Just as no two people are alike, no two lignins are alike.

Several variants of the lignin formula are found in the literature.

The figure shows a representation of the chemical structure of lignin recommended by the International Lignin Institute (ILI - International Lgnin Institute).

Lignins obtained from different plants differ significantly from each other in chemical composition.

The lignin molecule is indefinitely large and has many different functional groups.

The common structural unit of all types of lignin is phenylpropane (C 9 H 10), and the differences are associated with different contents of functional groups.

In accordance with modern knowledge, lignin is a complex three-dimensional network polymer of aromatic nature, resulting from the polycondensation of several monolignols - cinnamic alcohols (paracoumaric, conepheryl, synapic), see formulas.

Under normal conditions, lignin is poorly soluble in water and organic solvents. In chemical technologies and in the environment, lignin can participate in a wide variety of chemical reactions and transformations. Has biological activity.

Lignin exhibits plastic properties at elevated pressure and temperature, especially when wet.

Lignin utilization in nature

Lignin is practically not absorbed during digestion in higher animals; in nature, various fungi, insects, earthworms and bacteria are involved in its processing. The main role in this process is played by basidiomycete fungi. These include many fungi that live on both living and dead trees, as well as fungi that decompose leaf litter. Among the ligninolytic mushrooms there are edible ones (honey mushroom, oyster mushroom, champignon).

Degradation of polymeric lignin occurs under the influence of extracellular fungal oxidoreductase enzymes. These enzymes primarily include lininolytic peroxidases: lignin peroxidase and Mn peroxidase, as well as extracellular oxidase – laccase. Also, the ligninolytic complex of fungi contains auxiliary enzymes, primarily producing hydrogen peroxide for peroxidases and active oxygen farms. These include enzymes such as pyranose oxidase, glucose oxidase, glyoxal oxidase, alkyl aryl oxidase and cellobiose dehydrogenase.

The main product of lignin decomposition in nature is humus. Lignin decomposition under natural conditions occurs in the presence of other elements of plant tissue - cellulose and hemicellulose.

Economic importance of lignin

Every year, the world produces about 70 million tons of technical lignins. Encyclopedias write that lignin is a valuable source of chemical raw materials. Unfortunately, these raw materials are not yet available organizationally, economically and technically.

For example, the decomposition of lignin into simpler chemical compounds (phenol, benzene, etc.) with comparable quality of the resulting products is more expensive than their synthesis from oil or gas. According to the International Lgnin Institute, no more than 2% of technical lignins are used in the world for industrial, agricultural and other purposes. The rest is burned in power plants or buried in burial grounds.

The difficulty of industrial processing of lignin is due to the complexity of its nature, the multivariance of structural units and connections between them, as well as the instability of this natural polymer, which irreversibly changes its properties as a result of chemical or thermal effects. As stated above, industrial waste does not contain natural protolignin, but largely modified lignin-containing substances or mixtures of substances that have great chemical and biological activity. In addition, they are contaminated with other substances. It is believed that living near “ligno-storages” is not entirely beneficial. They have the unpleasant property of spontaneous combustion with the release of sulfur, nitrogen and other harmful compounds, and extinguishing them is extremely difficult due to their large size and the characteristics of the combustion process. In the photo on the left is a “lignostorage”, on the right is burning lignin.

Some studies have noted the mutagenic activity of technical lignins.

Thus, in the national economic balance, technical lignins still represent a significant and constantly growing negative value.

Properties of hydrolytic lignin

Hydrolytic lignin is an amorphous powdery substance with a density of 1.25-1.45 g/cm 3 from light cream to dark brown color with a specific odor. Molecular weight 5000-10000. Lignin particle sizes range from several millimeters to microns (or less). The content of lignin itself in hydrolyzed lignin ranges from 40-88%, difficult-to-hydrolyze polysaccharides from 13 to 45%, resinous substances and substances of the lignohumic complex from 5 to 19%, and ash elements - from 0.5 to 10%.

Composition of lignin ash: Al 2 O 3 – 1%; SiO 2 – 93.4%; P 2 O 5 – 1.5%; CaO – 1.5%; Na2O – 0.3%; K 2 O – 0.3%; MgO – 0.3%; TiO 2 – 0.1%.

Lignin is non-toxic and has good sorption capacity.

In dry form it is a highly flammable substance; in spray form it can be hazardous. Solid carbon content up to 30%. The calorific value of dry lignin is 5500-6500 kcal/kg and is close to the caloric value of standard fuel (7000 kcal/kg). The ignition temperature of lignin is 195°C, the self-ignition temperature is 425 o C and the smoldering temperature is 185 o C. The self-ignition temperature of: lignin airgel is 300°C, air suspension is 450°C; lower concentration limit of flame propagation 40 g/m 3 ; maximum explosion pressure 710 kPa; maximum rate of pressure rise 35 MPa/s; minimum ignition energy 20 mJ; The minimum explosive oxygen content is 17%.

Some areas of application of hydrolytic lignin:

Production of fuel briquettes, incl. mixed with sawdust, coal and peat dust;

Production of fuel gas, incl. with electricity generation in gas piston gas generators;

Boiler fuel;

Production of briquetted reducing agents for metals and silicon;

Production of coals, including activated ones;

Sorbents for cleaning urban and industrial wastewater, sorbents for spilled oil products, sorbents for heavy metals, technological sorbents;

Sorbents for medical and veterinary purposes (“Polyphepan”, etc.);

Blowing agent in the production of bricks and other ceramic products (instead of sawdust and wood flour);

Raw materials for the production of nitrolignin (a viscosity reducer for clay solutions used in drilling wells);

Filler for plastics and composite materials, binder for composite materials (“Arboform”, lignoplasts, etc.);

Preparation of organic and organic-mineral fertilizers, structure-forming agents for natural and artificial soils, herbicide for the cultivation of certain crops (legumes);

Raw materials for the production of phenol, acetic and oxalic acids;

Additive to asphalt concrete (preparation of lignin-bitumen mixtures, etc.).

Lignosulfonates

Lignosulfonates are water-soluble sulfonate derivatives of lignin, formed during the sulfite method of delignification of wood, representing sodium salts of lignosulfonic acids with an admixture of reducing and mineral substances.

Commercial lignosulfonates are obtained by evaporation of desugared sulfite liquor and produced in the form of liquid and solid concentrates of sulfite-alcohol stillage (molecular weight from 200 to 60 thousand or more), containing 50-90% of the dry residue. Lignosulfonates have high surface activity, which allows their use as surfactants in various industries, For example:

In the chemical industry - as a stabilizer, dispersant, binder in the production of briquetted plant protection products;

In the oil industry - in the form of a reagent for regulating the properties of drilling fluids;

In foundry production - as a binding material for molding sands, additives to non-stick paints;

In the production of concrete and refractories - as a plasticizer for mixtures;

In construction for strengthening low-strength materials and soils, as well as for removing dust from road surfaces, as an emulsifier in road emulsions;

In agriculture and forestry for anti-erosion soil treatment;

As a raw material for the production of vanillin;

Additive for granulating dusty materials, anti-caking agent.

Sulfate lignin

It is a solution of sodium salts characterized by high density and chemical resistance. Dry sulfate lignin is a brown powder. The size of lignin particles varies in a wide range from 10 (or less) microns to 5 mm. It consists of individual porous spherical particles and their complexes with a specific surface area of ​​up to 20 m 2 /g.

Sulfate lignin has a density of 1300 kg/m3. It is soluble in aqueous solutions of ammonia and alkali metal hydroxides, as well as in dioxane, ethylene glycol, pyridine, furfural, and dimethyl sulfoxide.

Industrially produced sulfate lignin contains on average, %: ash - 1.0-2.5, acid per sulfuric acid - 0.1-0.3, water-soluble substances - 9, resinous substances - 0.3-0.4 , Klason lignin - about 85. Lignin has a fairly constant functional composition. Sulfate lignin contains sulfur, the mass content of which is 2.0-2.5%, including unbound sulfur - 0.4-0.9%.

Thermal treatment of sulfate lignin causes its decomposition with the formation of volatile substances starting at a temperature of 190 o C.

Sulfate lignin is classified as a practically non-toxic product; when used in the form of a wet paste, it does not generate dust and is not a fire hazard.

Directions for using sulfate lignin:

Raw materials for the production of phenol-formaldehyde resins and plastics;

Binder for paper boards, cardboards, particle boards and fiber boards;

Additive - modifier of rubbers and latexes;

Chemical foam stabilizer;

Plasticizer for concrete, ceramic and refractory products;

Raw materials for the production of active brightening carbons of the collactivite type.

Literature about lignin and its applications

A very large literature is devoted to lignin and technical lignins (dozens of books, hundreds of dissertations and thousands of journal articles) in all major languages. Many of them are also available on the Internet, see, for example, the “Lignin” article on Wikipedia.

To get a first impression you can use, for example, The following books are available online:

Chemistry of lignin, F.E. Browns, D.A. Browns, M. Timber Industry, 1964;

Chemistry of wood and cellulose V.M. Nikitin, A.V. Obolenskaya, V.P. Shchegolev M. Timber industry, 1978;

Processing of sulfate and sulfite liquors, ed. P.D. Bogomolov and S.A. Sapotnitsky, M. Timber industry, 1989;

Structural materials from lignin substances, V.A. Arbuzov, M. Ecology, 1991.

Note. Existing technologies for processing and delignification of cellulose raw materials are associated with large capital investments and are not entirely perfect from the point of view of ecology and other factors. Scientists have long been looking for other, more effective ways to organize cellulose and biochemical production, but so far these developments have not found wide industrial applications.

Many contradictory problems of the development of biochemical production are reflected in a drop of water in the problem of the Baikal Pulp and Paper Mill, where there has been a long-term struggle to close the plant. It is possible that the plant will be closed. Of course, many residents of our country would like to live in a place as ecologically clean as the Baikal region and drink the same clean water as from Lake Baikal. Unfortunately, this is impossible and will not soon be possible, even theoretically. Over the past 100-150 years, the developed territory of our country, for various reasons, has been polluted faster than its self-cleaning capabilities allow. To some extent, this is a payment for economic progress, and to some extent, it is a payment for the frivolity or greed of leaders.

The level of consumption and production of pulp, paper and other biochemical products are considered the most important indicators of the development of the economy as a whole for large countries. Of course, it is not biochemists who make a decisive contribution to the pollution of nature with various wastes and harmful substances, but where there are large biochemical enterprises, their contribution to the pollution of the atmosphere and water resources can be very significant.

It is obvious that the leaders of the forest chemical sub-industry have been quite successful in blackmailing the state for decades, and it seems that this phenomenon continues to this day. The hostages, as always, are enterprise workers, local residents and “our little brothers.” The closure and repurposing of the Priozersk pulp and paper mill has already brought a noticeable improvement in the ecology of Lake Ladoga, however, a large number of Priozersk residents remain unemployed to this day, and the city of Priozersk is in a depressed state.

It would be wrong to deny the possibility of using lignin in industry and agriculture. For decades, hundreds of scientific organizations around the world have been engaged in research and development in the field of utilization of freshly extracted and stored lignin. Many of them have already been introduced into industry over the years. These works gain additional relevance in light of the increased interest in recent years in solving environmental problems and in the industrial use of the entire range of plant resources (biorefinery).

Most likely, it will not be possible to solve the problems of rational development of biochemical production without government attention, because the market does not have a head, and its nerve nodes, like those of an earthworm, are located in the esophagus. Which, in fact, was once again proven by the “started in 2008” economic crisis. Whether it happened with the help of his famous invisible hand or another hidden member does not matter.