Kaolin, fire clay

Clays are classified into six groups by the U.S. Bureau of Mines (1) kaolin, ball clay, fire clay, bentonite, fuller s earth, and common clay and shale. About half the toimage of clays produced in the United States is in the last category. In terms of monetary value, however, ka olin accounts for about two-thirds of the doUar volume. 

Tne insulating firebrick is a class of brick that consists of a highly porous fire clay or kaolin. Such bricks are light in weight (about one-half to one-sixth of the weight of fireclay), low in thermal conductivity, and yet sufficiently resistant to temperature to be used successbilly on... 

When tlia kaolin was replaced by fire-clay, and the -potassa was added, having been previously fritted with silica, a mass was produced which, after exposure to... 

Traditional manufacture of ceramics is based on the use of fine natural raw materials which are capable of producing easily worked plastic mass (paste) with water. The formed bodies maintain their shape. The products are strengthened and the shape fixed by firing at temperatures which were attainable even in the primitive kilns. Kaolin and clays are the main raw materials which exhibit these required properties. 

Kaolin in the mixes has been partially or completely replaced by white-firing clays with good plasticity (cf. Table 4). The mix composition varies over fairly wide ranges some types also contain CaCOj. The so-called hard feldspar earthenware has the following composition 50 —55% clay components, 35 —45 % quartz, 6 —12% feldspar. 

Materials. Several sources of clays were used. Their compositions are given in Table I. Fired clays were prepared by heating the bentonite and kaolin at 600°-700°C for 24-48 hr. 

The minimum amount of clay necessary to solidify the standard waste solution completely was measured for several clays. A solid product is defined as one that can be filtered at 100 psi using a pressure filter, with no resulting liquid. The results of these measurements for solidification of the standard waste solution are given in Table X. These results indicate that less volume is necessary if kaolin is used. Reactions with fired clays have resulted in volume increases as low as 20% (10). 

Forming techniques used for clay-based ceramics require control of water content in the batch. Water content, in turn, affects the response of the clay during forming [27], As the water content of the batch increases, the yield point of the clay-water mixture, and thus the force required to form the desired shape, generally decreases [26], However, the relationship is complex and depends on the composition of the clay, its structure, additives to the batch, and other factors [14], One method for quantifying the behavior of clay-water pastes is to measure the plastic yield point as a function of water content [14], The water contents and maximum yield points in torsion are compared for several clays in Table 9. Kaolins and plastic fire clays require the least amount of water to develop their maximum plasticity, ball clays require an intermediate amount, and bentonite requires the most. 

Same as 1, but less strong vitreous bond partly pure oxides Fire clays, mullite, sillimantine, corundum (kaolin-bonded)... 

Kaolin Paper 7.2 Kaolinite is a hydrous aluminum silicate kaolin is a white firing clay, primarily composed of kaolinite... 

The materials that fulfil all the conditions stated in this definition are kaolin, china clay, bentonite, bleaching earth, common clay, ball clay, fire clay, and refractory clay. The different aspects of the definition are explained below. 

Ceramic processing occurs through some sequential activities, which starts with raw materials, proceeds through batch preparation and forming and concludes with firing. The sequence of steps is illustrated by Fig. 8.7. Ceramics are formed from raw materials used for traditional ceramics which are different from those used for advanced ceramics. For traditional ceramics raw materials consist of silica, clay, fluxes and are refractory materials. Silica is obtained either from massive quartz deposit or pure quartz sands. The quartz is washed and groimd. The most commonly used clay minerals are kaolin and talc. China clay is predominantly kaolin. Ball clays are finer particle size elays that contain... 

Six types of clays are generally mined ball clay, bentonite, vermiculite, common clay and shale, fire clay. Fuller s earth, and kaolin. Most domestic clays are... 

Ceramics are products made from fired clay-containing masses such as kaolin. The products are distinguished by the grain size of the clay and additives used and the firing temperature. 

KAOLIN. (China clay.) Al203-2Si02-2H2O). The terms kaolin and china clay are used interchangeably to describe a type of clay which fires to a white color and has a PCE of 34-35. 

China clay - This is a ceramics industry term synonymous widi what is today ealled simply kaolin. China clay is substantially pme white or near-white kaolinite characterized by low plasticity, low green strength, and good fired whiteness. 

There are a number or types of special brick obtainable from individual producers. High-burned kaolin refractories are particularly valuable under conditions of severe temperature and heavy load or severe spalling conditions, as in the case of high-temperature oil-fired boiler settings or piers under enamehng furnaces. Another brick for the same uses is a high-fired brick of Missouri aluminous clay. 

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