CLAY (a clay; n the Tone; f Argiles; and argilla….) – Sedimentary rock composed mainly of clay minerals; with water to form dough, dries able to maintain shape given to it, and get the hardness of stone after firing. To include clays and some rocks, not natively possessing ductility and not soak in water (for example argillite). Particle size clays belong to the species, consisting, by weight more than 50% of particles of up to 0.01 mm. By increasing the amount of coarse-grained material of clay and sands valevrity pass.
The main chemical components of clays – SiO2 (30-70%), Al2O3 (10-40%) and H2O (5-10%); present in subordinate amounts of Fe2O3 (FeO), TiO2, CaO, MgO, K2O, Na2O, CO2, less MnO, SO3, P2O5. The composition of clays consists mainly kaolinite, monotermit, montmorillonite, halloysite, hydromica sometimes palygorskit.414UwOiMa28
Clays are classified by composition, origin, color, in their practical use. If one of the predominant mineral, clay mineral for this call – kaolinitic, etc. galluazitovaya Most clay is represented by a mixture of three or more minerals, ie, It is polymineral.
Typically, the clay contains impurities, fragments of different rocks or minerals, organic matter, and the newly-formed minerals, with a large content of which there is a transition from the actual clay to marl, clayey sands, shale coals, and others. From the chemical, mineralogical and particle size distribution of clays depend on their numerous physico-chemical and technological properties (plasticity, swelling, shrinkage, sintering behavior, fire resistance, distension, adsorption, etc.), which determine the industrial applications of clay and argillaceous rocks.
Clays and argillaceous rocks form about half of the sedimentary rocks of the crust. Chief glinoobrazuyuschy process -vyvetrivanie and physico-chemical decomposition of rocks containing alumina and silica. Favorable conditions for the formation of strong weathering crusts are on platforms. When erosion weathering crusts in water basins are formed well elutriated clay, occurring in sedimentary rocks of all types (inland, coastal lagoons and the sea).
By the nature of the technical requirements of the industry among the clays are four most important groups: low-melting; refractory and refractory; kaolin; adsorption (highly dispersed montmorillonite).
Fusible clay – polymineral, usually iron-montmorillonite and hydromica (often with an admixture of sand and organic matter), the rate of fire resistance of at least 1,350 ° C. Used for the preparation of heavy clay products, building clay bricks, tiles, drainage pipes, cement and others. The best varieties of plastic clays used for making pottery and sculptures. Fusible clay used to produce expanded clay (see. Keramzite raw materials). Harmful impurities are coarse fragmental inclusions, especially limestone and gypsum. clay suitable for the production of a particular type of product is determined by the technological tests, as a result of which the manufactured product is determined by the quality of the factory. On clay brick, ceramic drainage pipe, concrete block and other products of rough ceramics in the USSR established state standards. 9GOST 9169-75 “Raw clay for the ceramics industry” defines the main features of the classification of raw materials. On certain types of clay are republican standards, for example, PCT RSFSR 303-72 “potter’s clay” take into account the clay intended for the manufacture of pottery. Fusible clays are to popular raw materials and the state balance of minerals of the USSR are not counted. In 1982, for the heavy clay products in the Soviet Union produced about 200 million. M3 of clay.
Cement argillaceous rocks used in the cement industry to produce a mixture with Portland cement clinker carbonate rocks. The cement industry is used mainly fusible clay, takzheargillity, shales, loam et al., The suitability of which is determined mainly by the chemical composition. Cement clays contain a certain ratio silica, alumina and iron oxide. Kremnezёmny module is within 1.7-3.5, alumina modulus may range from 1.0 to 2.5. A disadvantage of the individual components corrected in clays of natural or artificial introduction of additives (iron ore, bauxite, fly ash and others.). Harmful impurities cement clay – magnesium oxide, alkali, phosphorus, sulfur compounds, chlorine, psephytic material (fraction larger than 0.08 mm). General requirements for cement clays not. The quality of their study in each case, the institutions of the cement industry on the basis of special technological tests. Average consumption of cement per 1 ton of clay cement clinker 350 kg. By industrial categories are explored reserves of cement clays in the USSR up to 4 billion tons.; annual production of about 27 million. tonnes (1983).
Refractory and refractory clay are characterized by a high content of alumina (20-42%), a high binding capacity and ductility; they serve as raw materials for a variety of ceramic production, primarily for the production of sanitary earthenware, refractory and acid products. Refractory clays have monomineral composition (or kaolinitic monotermitovy) and fire resistance not less than 1580 ° C. Refractory clay is usually not observed in mineral composition and have a fire resistance from 1350 to 1580 ° C. Uniform requirements for the quality of refractory and refractory clay is not. There are various specifications developed in relation to the feed of each field and the type of product manufactured from it, which are limited to refractory clays, their particle size, composition and content of iron, alkali and other chemical components. In addition, there are a number of guests on the refractory, acid-resistant ceramic products and for products of building ceramics, clay suitable for the manufacture of semi-works is determined by the technological challenges. In the USSR, known deposits of refractory 76 and 94 deposits of refractory clay with balance reserves of industrial categories in the amount of 1,398,100,000, respectively. T and 576 400 000. Tonnes (1983). The bulk of the reserves are located in the territory of the RSFSR and the Ukrainian SSR. Inventories 20 deposits of refractory and refractory clay deposits 3 exceeded 20 million tonnes (Zatishanskoe – 93.5 million tons, Berlin -. 188.2 million tonnes.).. Production is carried out mainly by open method, but some fields (for example, Borovichi) developed by underground methods.
Kaolin – a kind of clay, composed predominantly kaolinite, has no inherent plasticity clays, high dispersion and large binding capacity. Primary kaolin and quartz-kaolin sands almost entirely fed to the enrichment (see. Kaolin).
Adsorption on clay mineralogical composition is mainly montmorillonite, have a high binding capacity, the high capacity of exchangeable bases, adsorption and catalytic activity. To this group of clays are bentonites.