What is the name of white clay? Clay medicinal properties and uses, human use of clay

Clay refers to secondary rocks that were formed as a result of weathering of rock masses during the evolutionary process. Clay is used more often than other materials as a building material. The composition of clay is very complex and variable. In its pure form, clay contains practically no impurities. The diameter of its particles does not exceed 0.01 mm; as a rule, clay is plastic. All types of clays contain chemically bound water; it is retained in the form of thin films between particles of clay material.

The clay contains silicon and aluminum components. The most common impurities are iron hydroxide, alkali earth metal oxides, quartz and iron sulfide. Rocks with a high alumina content are used to produce refractory materials; the alumina content in such rocks ranges from 25 to 30%.

When all types of clays get wet, water fills the gaps between the particles, as a result of which they easily move relative to each other. This property determines the plasticity of clay materials.

Clay material is widespread in nature. Clays are divided into subgroups depending on the mineral composition and particle diameter, the presence of certain impurities. There are these types of clay:

red,
white,
sandy,
clay for porcelain,
kaolin

The granulometry of certain types of materials depends on the mineral components and chemical composition. Almost all varieties of this unique fossil are characterized by plasticity, adsorption, and swelling. When wet, shrinkage and swelling are characteristic; these properties are decisive when using the material in industry.

According to industrial technical requirements, rock is divided into varieties:

low-melting,
refractory,
adsorption,
kaolin

Soaked clay becomes plastic and can take almost any shape.

Plastic masses are called “greasy” because they feel like a greasy material to the touch. Varieties of clays with a low degree of plasticity are called “lean” or lean. Products made from such materials quickly crumble; “lean” clay is not suitable for brick production.

Dried clay holds the shape it was given well, while it slightly decreases in volume, compacts, hardens and becomes as strong as stone. Due to these properties, clay has long been considered the most widely used material for making dishes and other household items.
Among other things, this breed has the ability to be sticky.
Having absorbed a certain amount of moisture, the material no longer allows water to pass through; this property determines the water resistance of the material.
Another property of clay is its covering ability. Due to this property, clay has long been used to cover the walls of buildings and furnaces.
The sorption capacity of the material makes it possible to use clay as a purifier of fats and petroleum products.

All of the above properties ensure a long service life for objects made from clay.

Types of clay and their origin

Based on their origin, clayey materials are divided into subgroups.

Sedimentary clays. They are formed as a result of the application of destroyed rock layers by water flows. These materials are divided into marine and continental. From the name of the first it is clear that clay is formed on the seabed, in the second case the formation occurs on continents, in the bottom sediments of rivers and lakes.

Under natural conditions, this variety has a brown tint; it is given to the material by iron-containing compounds - ferrum oxides, which are contained in clay in an amount of 5 to 9%. These are usually sedimentary clays. They are formed as a result of the application of water to destroyed rock layers.

During the firing process, red clay turns red or white, depending on the process conditions and the type of firing equipment. This variety can withstand heating up to 1100 degrees.

This type of clay is flexible and kneads well. The high elasticity of the material determines its use as a material for sculptural modeling.

Natural mineral deposits are found everywhere. They often accumulate in sea or fresh lagoons. In the case of sea bays, clay is a heterogeneous mass and has numerous impurities.

When wet, the clay acquires a light gray tint; as a result of the firing process, it turns into a beautiful white material. This type of clay is characterized by elasticity.
Due to the absence of iron compounds, white clay is slightly translucent. It is widely used for the production of household items, dishes, jugs, and decorative figurines. In addition, the material is used in the production of tiles and sanitary ware.
Objects made from this clay are covered with glaze, kept in ovens at 900-950 degrees.

Porous mass for ceramic production

The raw material is a clayey material with a low calcium content and high porosity.

This clay consists of kaolinite, illite and other aluminosilicates, and also contains inclusions of sand and carbonates. Silica and alumina are the basis of clay minerals.
Porous mass refers to sedimentary types of clay. It is formed as a result of the application of water to destroyed rock layers.
The natural color of such clay ranges from white to brown. Greenish clays are also found. The material is fired at low temperatures.

Majolica

This is a low-melting type of clay material that contains a large amount of white alumina. The raw materials are fired at low temperatures. Majolica is glazed with special mixtures containing tin compounds.

The word “majolica” comes from the name of the island of Majorca, where this material was used for the first time. Majolica was widely used in Italy. Traditionally, objects made from majolica are called earthenware, because for the first time they began to be produced in special departments for the production of earthenware.

Fireplace clay mass

The composition of this rock includes quartz, a significant amount of feldspar and fireclay. These are shelf rocks by origin. They are formed at a depth of about two hundred meters. A prerequisite is the absence of any kind of currents.

Black material. After firing, the mass resembles ivory products in color. Thanks to the use of glaze, products made from raw materials become unusually durable and have high water resistance.

This raw material is a baked mass. It is fired at a temperature of 1100 - 1300 degrees. The firing process is carried out under careful supervision in compliance with technological rules, otherwise the clay products may crumble.

Stone ceramic mass is used for modeling and for the manufacture of various ceramic objects. Products made from this material are very beautiful. Stone ceramics has unique technical properties.

The raw material includes feldspar, a significant amount of quartz and kaolin. This type of clay does not contain iron impurities.

When wetted with water, the mass acquires a gray tint, and after the firing process it becomes perfectly white. The material is fired in ovens at a temperature of 1300 - 1400 degrees. This raw material is very elastic.

It is not recommended to use this variety for working on pottery wheels. The material is very dense, practically without pores, water absorption is very low. The burned material becomes transparent. Objects made from porcelain clay material are coated with various glazes.

Materials for rough ceramics

Large-porous clay is used for the production of large objects and is often used in construction. Products of the material are characterized by high heat resistance; they can withstand temperature fluctuations well.

The plastic properties of raw materials depend on the presence of quartz and aluminum in the compound. The characteristic features of the material are due to the presence of a significant content of fireclay and alumina.

The material belongs to the refractory variety. Melting point – 1400-1600 degrees. The coarse ceramic material sinteres perfectly and practically does not shrink. These properties determine its use for the production of dimensional objects, as well as large panels and mosaics.

Montmorillonite clay

The raw material is used as a bleaching agent in the purification of tent syrups, in brewing, in the production of juice and refined oils. This material improves the quality of finished products; in addition, this type of clay is used as a means to combat rodents and insects.

Adsorption clay

A characteristic feature is high binding properties and a high degree of catalysis. The most common adsorption clay is bentonite.

Colored clay materials

Multi-colored clay is a material that contains oxides of metallic elements or pigments, and is a homogeneous mixture.

When pigments penetrate into the thickness of the material, some of them remain in suspension, and the uniformity of the tone of the raw material is disrupted.
Natural pigments give clay a particular shade; they are divided into two categories: oxides of metal elements and coloring substances themselves.
Oxides are natural components of natural origin, formed in the thickness of the earth. These substances are purified and finely ground. Copper oxide is most often used to give clay a particular color. During the firing process, this substance acquires a greenish tint as a result of the oxidation process.
To give the material a blue tint, oxygen-containing cobalt compounds are used. Chromium compounds provide the color of olives, while magnesium and nickel compounds provide brown and gray, respectively.
Coloring components are added to raw materials in amounts from 1 to 5%. Higher pigment contents may cause undesirable effects during the firing process.

Scope of application

Clay is actively used in construction for the manufacture of bricks and ceramic products. It has undeniable advantages, as well as a relatively low cost. The advantages of this raw material include heat resistance, adsorption properties, environmental friendliness, and breathability.

Clay is a sedimentary rock that has a fine-grained structure. This is a very interesting type of rock in its properties, because in a dry state it is crumbly and looks like dust, but when moistened it is soft and plastic, capable of taking any given shape. When it hardens after moistening, the clay becomes surprisingly strong and durable.

Clay is a sedimentary rock, which is a secondary product of the earth's crust, which was formed as a result of the destruction of rocks through weathering.

The most important source for the formation of clay is feldspar, which, during the process of decomposition under the influence of precipitation, forms kaolinite and other clay components.

Minerals in clays

Clay contains one or more minerals from the group of kaolinite, montmorillonite, or other layered clay minerals. Clay may also contain carbonate and sand particles.

Depending on the quantity and quality of the minerals that make up the clay, this mineral can be of a variety of colors and shades - light yellow, orange, reddish brown, gray, white and many others.

Different types of clay contain the following minerals:

kaolinite
andalusite
montmorillonite
halloysite
muscovite
hydrargillite
nacrite
diaspora
pyrophyllite
corundum
monothermite

There are also some types of minerals that contaminate clays. Among them are the following:

quartz
calcium
dolomite
glauconite
limonite
magnetite
marcosite
rutile
pyrite
serpentine
siderite

Bentonite clay contains montmorillonite

Properties of clay

Among the main characteristic properties of clay are the following:

High level of ductility
Ability to take any given shape
Fireproof properties
Air and thermal shrinkability
Excellent sinterability
Viscosity of clays of various grades
Degree of shrinkage
Clay porosity
Swelling of clays
Density
Waterproof

Types of clay

There are several types of clays, including the following:

Kaolin- this is the name of the famous white clay, which is used to produce beautiful porcelain and fireproof products.
Construction clay- used for preparing solutions that are used in the process of constructing structures for various purposes.
Shale- used in the cement production process.
Fire-clay- Suitable for the manufacture of refractory bricks and other heat-resistant products.
Bentonite— when immersed in water, it increases in volume several times; it is used in drilling fluids in the process of drilling wells.
Smectite- has bleaching and filtering properties. Filters made from cloth clay are widely used to remove impurities from petroleum products, as well as various types of oils - both edible and technical.
Pottery(lump) clay is used in the process of making pottery.
- used as a medicinal and cosmetic product for applying masks to the face and body.
Sandstone clay- used for making dishes, decorative ceramics and souvenirs.

Kaolin - white clay

Scope of application of clay

After combining with the right amount of water, clay is able to form a dough-like mass with plastic properties. Depending on the location of the deposit of this natural raw material, clay is characterized by different quality indicators. Therefore, it is used for various purposes. Among the areas of application of various types of clay are the following:

Ceramics production- one of the most important areas of application of clay. Various varieties of this natural material are used to make excellent examples of ceramic tableware, earthenware, etc. The art of pottery dates back several thousand years, and continues to improve today.

Manufacturing of building materials— clay is widely used in production. Today, the vast majority of brick products are produced in factories, but there is also an artisanal method of hand-molding bricks, which is successfully used in some regions.

Cement production— a mixture of clay (25%) and limestone (75%) is used to make cement. During the production process, the raw materials are carefully crushed and then thoroughly mixed. In this case, a strict dosage of components must be observed, otherwise the result will be of poor quality.

Technical ceramics represents a fairly extensive group of special ceramic products made from a plastic mass, the basis of which is clay. for technical purposes is widely used in various areas of human life and activity - in the form of sanitary ceramics, as insulators of electric current in devices and wiring, and in many other areas.

adobe construction— adobe buildings are architectural structures, the main material for the construction of which is clay. Mud houses are one of the first examples of ancient architecture. However, the methods of using clay may be different. Thus, the clay mass can be compacted into a mold made of wooden planks, or the clay can be mixed with crushed straw and the board base can be covered with this mixture.

Medicine and cosmetology— Clay has long been widely used for medicinal and cosmetic purposes. Clay is included in some medicinal ointments, as well as sorbents and preparations for getting rid of diarrhea. And in cosmetology, clay is used to make masks for the face and body, and also includes it in some creams.

Edible clay- Some types of clay are edible and are eaten. Edible clay is a special additive to the basic human diet and is a valuable source of mineral salts and trace elements. Edible clay serves as a sorbent of natural origin, which helps cleanse the human body of slag deposits and harmful toxins. At the same time, clay has an enveloping effect and can be used as a natural antiseptic.

Details Created 08/09/2011 21:57 Updated 05/24/2012 03:10 Author: Admin

Clays were formed as a result of natural weathering of igneous feldspathic rocks - mainly granites, volcanic glass, tuffs, porphyrites, as well as due to the destruction of metamorphic rocks (gneisses), etc.

As a result of weathering, feldspars are transformed into a clayey substance, which is formed mainly in the form of kaolinite minerals according to the following scheme (for orthoclase):

The reasons for this decomposition of feldspathic rocks are physical (temperature fluctuations, freezing of water, crystallization of salts), chemical (under the influence of atmospheric oxygen, carbon dioxide, water, organic acids) and biological (vital activity of microorganisms) weathering. As a result of physical and chemical weathering on various rocks and deposits, a weathering crust appears.

Weathering crust minerals are formed in two ways - synthetically, for example, by converting feldspar into individual oxides - Al 2 O 3 and SiO 2
and by coagulation of these oxides into the mineral composition kaolinite, and by hydrolysis of primary minerals. The minerals kaolinite, illite (hydromica) and montmorillonite are the main rock-forming minerals of clay raw materials.

The word “clay” means fine-clastic sedimentary rock consisting of mineral particles less than 0.005 mm in size, chemically representing hydrous aluminosilicates and accompanying impurities of other minerals. Since granites, together with transitional varieties, make up approximately all igneous rocks, i.e. there are much more of them in nature than others, sedimentary rocks contain the largest amount of clay (as a decomposition product of the most common minerals of igneous rocks - feldspars, for example orthoclase , albite, anorthite).

It is estimated that the earth's crust consists of 95% igneous rocks and 5% sedimentary rocks, of which 4% are clays only. Clays can be primary, which remained in the place of their formation, and secondary, which were deposited in new places as a result of alluvial, deluvial, fluvio-glacial, aeolian and other processes. Primary clay, moving in one of these ways, for example, by water, could be freed from the impurities that originally accompanied it and therefore be deposited in a new place in a purer form, while improving in quality. This is how kaolins were formed, characterized by a high content of the mineral kaolinite, high fire resistance, and a low content of coloring oxides, as a result of which they acquire a predominantly white color before and after firing.

Clays with a slightly increased content of fluxes and coloring oxides are classified as a special type - refractory clays, and clays containing a significant amount of impurities (coloring oxides, fluxes, etc.) become fusible - ordinary clays. If we divide clay raw materials according to the area of application in industry, then pure white kaolins and some refractory clays (white-burning raw materials) are included in the groups of porcelain and earthenware, refractory - in the groups of pipe, clinker, terracotta, and low-melting clays - in the groups of pottery, brick-tile, expanded clay clays.

Clays of Quaternary and Upper Tertiary age, which especially often satisfy the requirements for clay raw materials for the production of bricks, tiles, expanded clay and other ceramic materials and products, are characterized by the presence of a significant admixture of sand particles and the polymineral nature of the clay part. Among the clay minerals in these rocks, hydromica usually predominates. Kaolinite and montmorillonite are of minor importance, and other minerals (chlorite, halloysite, etc.) are present as impurities.

Small amount kaolinite does not significantly affect the increase in firing temperature, and montmorillonite significantly reduces it, which is a valuable quality in the manufacture of building bricks. For the manufacture of some types of bricks and ceramic tiles in Russia, the USA and some other countries, loess rocks are used - widespread quaternary deposits containing, in addition to sand and clay, a lot of fine dusty material (50-70%).

Clay rocks can be in loose and stone-like states. But no matter what state these rocks are in, they contain a group of finely dispersed minerals that give the clay plasticity, the ability to be molded (for stone-like ones after fine grinding) and retain its given shape after drying. This group of minerals, which are hydrous aluminosilicates, is called clay or clay substance.

Except kaolinite clays are widely distributed in nature hydromica. They are formed as a result of weathering of silicate rocks in humid climates and are products of the first stage of chemical weathering. The main rock-forming minerals in these clays are hydromica, including glauconite, and the minor ones are kaolinite and montmorillonite. Primary hydromica clays are found in the weathering crust of crystalline rocks, secondary ones are represented by continental sediments - lake, river, glacial, marine (shelf) and lagoon sediments.

A special type of clayey rock is bentonite. It was formed by weathering of effusive rocks, tuffs, volcanic ash, etc. (it received this name from the name of the American Fort Benton, in the area of which it was first discovered).

Bentonite consists mainly of minerals of the montmorillonite group, but also contains impurities. It is used for the preparation of porcelain masses, washing solutions for drilling, as an adsorbent for liquid clarification,
when enriching iron ores, etc.

Polymineral clays are formed when sedimentary differentiation of matter is not perfect enough. Most of these clays are of secondary origin. They are widely developed in deluvial sediments, in alluvial deposits, rarely in marine sediments and sometimes in the weathering crust. They contain hydromica, kaolinite, montmorillonite, quartz, and micas. They are used for the manufacture of rough ceramic products. Some of their varieties are suitable for producing expanded clay.

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Pigments are inorganic compounds that color clay and glazes. Pigments can be divided into two groups: oxides and colorants. Oxides are a naturally occurring basic material that forms among the rocks of the earth's crust, is purified and atomized. The most commonly used are: copper oxide, which takes on a green color in the oxidizing firing environment; cobalt oxide, which produces blue tones; iron oxide, which gives blue tones when mixed with glaze, and earth tones when mixed with clay. Chromium oxide gives the clay an olive green color, magnesium oxide gives it brown and purple tones, and nickel oxide gives it a grayish-green color. All these oxides can be mixed with clay in a proportion of 0.5-6%. If their percentage is exceeded, the oxide will act as a flux.pressing the melting temperature of clay. When painting products, the temperature should not exceed 1020 ° C, otherwise firing will not produce results. The second group is dyes. They are obtained industrially or by mechanical processing of natural materials, which represent a full range of colors. Dyes are mixed with clay in a proportion of 5-20%, which determines the light or dark tone of the material. All specialized stores have an assortment of pigments and dyes for both clay and engobes.

Preparing ceramic mass requires a lot of attention. It can be composed in two ways, which give completely different results. A more logical and reliable way: add dyes under pressure. A simpler and, of course, less reliable method: mix dyes into the clay by hand. The second method is used if there is no exact idea about the final coloring results or there is a need to repeat certain colors.

materials used:

Dolors Ross. Ceramics: technique. Techniques. Products./Trans. with him. Yu.O. Bem. - M.: AST-PRESS KNIGA, 2003.

Clay consists of one or more clay minerals - illite, kaolinite, montmorillonite, chlorite, halloysite, or other layered aluminosilicates, but may also contain sand and carbonate particles as impurities. Alumina (Al 2 O 3) and silica (SiO 2) form the basis of the composition of clay-forming minerals.
The diameter of clay particles is less than 0.005 mm; rocks consisting of larger particles are usually classified as silt. The color of clays is varied and is determined by Ch. in a way that colors them with impurities of mineral chromophores or organic compounds. Most pure clays are gray or white, but clays in red, yellow, brown, blue, green, purple and black are also common.

Origin

Clay is a secondary product formed as a result of the destruction of rocks during the process of weathering. The main source of clay formations are feldspars, the destruction of which under the influence of atmospheric agents forms silicates of a group of clay minerals. Some clays are formed by the local accumulation of these minerals, but most are sediments from water flows that accumulate at the bottom of lakes and seas.

In general, according to their origin and composition, all clays are divided into:

Sedimentary clays, formed as a result of the transfer to another place and deposition there of clayey and other products of the weathering crust. Based on their origin, sedimentary clays are divided into marine clays, deposited on the seabed, and continental clays, formed on the mainland.
- Among marine clays distinguish:
  - Coastal-sea - formed in coastal zones (turbulence zones) of seas, open bays, river deltas. They are often characterized by unsorted material. They quickly change into sandy and coarse-grained varieties. Replaced by sandy and carbonate deposits along strike. Such clays are usually interbedded with sandstones, siltstones, coal seams and carbonate rocks.
  - Lagoonal - formed in sea lagoons, semi-enclosed with a high concentration of salts or desalinated. In the first case, the clays are heterogeneous in granulometric composition, insufficiently sorted and wind together with gypsum or salts. Clays from desalinated lagoons are usually finely dispersed, thin-layered, and contain inclusions of calcite, siderite, iron sulfides, etc. Among these clays there are fire-resistant varieties.
  - Shelf - formed at a depth of up to 200 m in the absence of currents. They are characterized by a uniform granulometric composition and large thickness (up to 100 m or more). Distributed over a large area.
- Among continental clays highlight:
  - Colluvial - characterized by a mixed granulometric composition, its sharp variability and irregular layering (sometimes absent).
  - Ozernye, b. parts with a uniform granulometric composition and finely dispersed. All clay minerals are present in such clays, but kaolinite and hydromicas, as well as minerals of hydrous oxides Fe and Al, predominate in clays of fresh lakes, and minerals of the montmorillonite group and carbonates predominate in clays of salt lakes. Lake clays include the best varieties of fire-resistant clays.
  - Proluvial, formed by temporary flows. Characterized by very poor sorting.
  - River - developed in river terraces, especially in the floodplain. Usually poorly sorted. They quickly turn into sands and pebbles, most often non-layered.
Residual clays- clays resulting from the weathering of various rocks on land, and in the sea as a result of changes in lavas, their ashes and tuffs. Down the section, residual clays gradually transform into parent rocks. The granulometric composition of residual clays is variable - from fine-grained varieties in the upper part of the deposit to uneven-grained ones in the lower part. Residual clays formed from acidic massive rocks are not plastic or have little plasticity; Clays formed during the destruction of sedimentary clay rocks are more plastic. Continental residual clays include kaolins and other eluvial clays. In Russia, in addition to modern ones, ancient residual clays are widespread - in the Urals, in the West. and Vost. Siberia (there are also many of them in Ukraine) - of great practical importance. In the mentioned areas, clays predominantly montmorillonite, nontronite, etc. appear on basic rocks, and on medium and acidic rocks - kaolins and hydromica clays. Marine residual clays form a group of bleaching clays composed of minerals of the montmorillonite group.

Practical use

Clays are widely used in industry (in the production of ceramic tiles, refractories, fine ceramics, porcelain-faience and sanitary wares), construction (production of brick, expanded clay and other building materials), for household needs, in cosmetics and as a material for artistic works (modeling ). Produced from expanded clay clays By annealing with swelling, expanded clay gravel and sand are widely used in the production of building materials (expanded clay concrete, expanded clay concrete blocks, wall panels, etc.) and as a heat and sound insulating material. This is a lightweight porous building material obtained by firing low-melting clay. It has the shape of oval granules. It is also produced in the form of sand - expanded clay sand. Depending on the clay processing mode, expanded clay of varying bulk density (volumetric weight) is obtained - from 200 to 400 kg/m 3 and higher. Expanded clay has high heat and noise insulation properties and is used primarily as a porous filler for lightweight concrete, which has no serious alternative. Expanded clay concrete walls are durable, have high sanitary and hygienic characteristics, and expanded clay concrete structures built more than 50 years ago are still in use today. Housing built from prefabricated expanded clay concrete is cheap, high quality and affordable. The largest producer of expanded clay is Russia.

Literature

Gorkova I.M., Korobanova I.G., Oknina N.A. and others. The nature of strength and deformation characteristics of clayey rocks depending on the conditions of formation and moisture. - Tr. Laboratory hydrogeol. Probl., 1961, issue. 29