Raw kaoline

Konta, J., 1969. Raw kaolin from Osmosa-Bozi cany deposits in west Bohemia. Interceram, 59-60 102-104 115-117. 

Raw kaolin is mainly extracted by open cast mining. Secondary deposits can be exploited using excavators, whereas primary deposits of kaolin are often washed out of the rock with a high pressure water jet. 

To obtain a uniform mineralogical composition with a high alumina content (AI2O3 content > 37%), the raw kaolin is elutriated and simultaneously classified in hydrocyclones, whereupon kaolinite and the other layer silicates are separated from the accompanying quartz and feldspar on the basis of their different particle size distributions. 

Because of the varying composition of raw kaolin and different uses, raw kaolin generally requires processing (flotation, sedimentation, baking, etc.) to acquire characteristics suited to specific industrial uses. 

In the United States, aluminum sulfate is usually produced by the reaction of bauxite or clay (qv) with sulfuric acid (see Sulfuric acid and sulfur trioxide). Bauxite is imported and more expensive than local clay, generally kaolin, which is more often used. Clay is first roasted to remove organics and break down the crystalline stmcture in order to make it more reactive. This is an energy intensive process. The purity of the starting clay or bauxite ore, especially the iron and potassium contents, are reflected in the assay of the final product. Thus the selection of the raw material is governed by the overall economics of producing a satisfying product. 

Frequently kaolin clay is used for a raw material. In one of the older processes kaolin is treated with sulfuric acid at elevated temperature and subsequently washed to remove Hberated alumina and alkaUes. Kaolin can also serve as a raw material for preparing a number of synthetic zeofltes (21). 

Chemical Raw Material. In addition to use as a catalyst raw material, clays are used or have been extensively studied as chemical raw material. For example, kaolin has been investigated as a raw material for aluminum metal production. Kaolin has a 38 to 40% alumina content and is available in the United States in large quantities whereas the higher alumina bauxite reserves are very limited. The Bureau of Mines has actively carried out research in the aluminum from ka olin area for many years. Activity increases whenever imports of bauxite are threatened by war or other trade intermptions (1,22,23). 

This paper is concerned with the synthesis of Y zeolite with Si02/Al203 ratio of 4.5 from kaolin taken in Yen Bai-Vietnam and their catal3dic activity for the cracking of n-heptane. The synthesized sample (NaYl) showed the Y zeolite crystallinity of 53% and PI zeolite crystallinity of 32%, and exhibited good thermal stability up to 880 C. The activity and the stability of HYl turned out to be lower than those of standard sample (HYs), but the toluene selectivity was higher. The conversion of n-heptane to toluene might be due to the metal oxide impurities, which was present in the raw materials and this indicates the potential application of this zeolite for the conversion of n-parafRn to aromatics. 

Many powdered raw materials, e.g. china clay, talc and calcium carbonate are natural products, coming from the soil and often contaminated with appreciable numbers of bacterial and fungal spores. Products heated to high temperatures during preparation, e.g. calcined kaolin clay used as a titanium dioxide extender, will generally be free from such contaminants. 

Cost is also a most important factor in developing a commercially acceptable catalyst, and includes consideration of both manufacturing and raw material costs. Many catalysts which could meet operating requirements were too costly. To keep costs low, both zeolite content as well as type and rare earth content had to be considered. Kaolin as a low cost extender and filler was of considerable help, but again had its limits. 

E. the thixotropy, such as fly ash, hydrated hme, kaolin, diatomaceous earth and other raw or calcined pozzolanic materials and various rock dusts. [40, 42]. 

You have supplies of kaolin, silica, and mullite as raw materials. Using kaolin plus either silica or mullite, calculate the batch composition (in weight percent) necessary to produce a final microstructure that is equimolar in silica and mullite. 

Cordierite [12182-53-5/, Mg4Al4Si5018, is a ceramic made from talc (25%), kaolin (65%), and A Oj (10%). It has the lowest thermal expansion coefficient of any commercial ceramic and thus tremendous thermal shock resistance. It has traditionally been used for kiln furniture and more recently for automotive exhaust catalyst substrates. In the latter, the cordierite raw materials are mixed as a wet paste, extruded into the honeycomb shape, then dried and fired. The finished part is coated with transition-metal catalysts in a separate process. 

Two synthesis variables seemed to have received most attention in the work reviewed here, the cation composition and the nature and source of the aluminosilicate reactant. Extensive use of mixed bases of the alkali, alkaline earth, and organic cations have been reported as well as a wide variety of reactant aluminosilicates including solutions, hydrogels, glasses, kaolin (raw and calcined), and naturally occurring zeolites. 

High Alumina Clay Minerals. Several hydrated alumina minerals should be grouped with the clay minerals because the two types may occur so intimately associated as to be almost inseparable. Diaspore (a-AIO(OH)) and bochmitc (y-AIO(OH)). both AFOj H 0(AI Oi. 85% H 0. 15%) are Ihe chief constituents of diaspore clay, which may contain over 75% AhOj on the raw basis. Gibbsite, AliOj 3 HyO (AljOi. 65.4% HjO. 34.6%). and cliachite. the so-called amorphous alumina hydrate (much cliachite is probably cryptocryslalline), as well as Ihe monohydrates, occur in hauxile, bauxitic kaolin, and bauxitic clays. 

Aluminum is the most abundant metallic element in the earth s crust, comprising approximately 8% of the crust (Brusewitz 1984). Aluminum does not occur naturally in the metallic, elemental state, but rather occurs in combination with oxygen, silicon, fluorine, and other elements (Browning 1969 Dinman 1983 IARC 1984 NRC 1982). The most important raw material for the production of aluminum is bauxite, which contains 40-60% alumina (aluminum oxide) (Dinman 1983 IARC 1984). Other raw materials sometimes used in the production of aluminum include cryolite, aluminum fluoride, fluorspar, corundum, and kaolin minerals (Browning 1969 Dinman 1983 IARC 1984). 

X-ray diffraction is used to quantify the crystalline species such as zeolite, alumina, and kaolin in raw materials and finished products. Such information is used not only by research scientists, but also by quality assurance personnel during the manufacturing process. Changes in any of these materials can affect the catalysts performance and cost, therefore they must be precisely controlled. 

Ceramic powder processing technology is discussed in the Tao Shuo [9]. This text describes how kaolin raw materials had to be foimd and ground to the desirable size distribution. After grinding, the earth was washed and purified. This was done by mixing it with water in a large... 

Ti02, Kaolin, precipitated calcium carbonate, and beet sugar raw juice)... 

The parent kaolin used proceeds from Navalacruz (Zamora, Spain). X-ray diffraction of the raw sample shows the presence of quartz, smectite and mica as impurities. The amounts of these species were reduced by aqueous decantation of the < 2pm fraction. 

Porcelain is a typical representative of fine ceramics made from three principal raw materials kaolin (clay), quartz and feldspar (the so-called triaxial bodies). These raw materials in suitable proportion are ground and mixed with water in ball mills and homogenized in blungers. The entire procedure can be illustrated by the following flow sheet which is typical for the manufacture of traditional fine ceramics ... 

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