Calcined kaolin

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. 

Clay minerals are widely used in the filler industry and the production of the various types has been described by Hancock and Rothon [85]. The products available range from unaltered kaolin to products produced by calcination. Kaolin deposits are widespread throughout the world. While simple clay minerals are extensively used as fillers in elastomers, their use in thermoplastics is more restricted and the principal products used are those obtained by calcination of ka-olinite. Thus metakaolinite finds application in PVC and silane treated calcined clay in polyamides. The production of these forms only is discussed below. 

Calcined kaolin clays can be used in footwear (improved abrasion resistance) and cable (improved insulation properties). 

Ito et al. [13] described the preparation of a batch consisting of talc, kaolin, calcined kaolin, and alumina that collectively provide a chemical compound of Si02 45-55, AI2O3 32-40, and MgO 12-15 wt%. This mixture is used to produce cordierite monoliths,... 

The batches for rapidly fired porcelains have to be adapted to the short firing times to obtain product properties comparable with those of conventionally fired porcelains, despite the diffusion-controlled slow chemical reactions. Suitable mixtures contain lower concentrations of quartz and fluxes and contain prefired raw materials such as calcined kaolin (fireclay). Satisfactory tran.sparency can be obtained by using very Fine particulate quartz sorts, which dissolve sufficiently rapidly in the glass phase. 

Polishing Marl - a filler designed to replace diatomaceous earth and calcinated kaolin in automotive and household polishing formulations which improves H S due to the lack of crystalline silica Solvay Alkali GmbH, Rbeinberg, Germany... 

Thermo-optic grades - Optiwhite, Opti white MX, Optiwhite P, 30 P (see process discussion below) Burgess 2212, 2227 - calcinated kaolin surface treated with amino silane... 

China Clay Lion - soft kaolin for use in cosmetics, pharmaceuticals, rubber, paint, paper Calcinated Kaolin Clay - high brightness Plus White Kaolin - paper industry grade Electros Kaolin USP - pharmaceutical and cosmetics grade Kaolin SIM 90 - exceptional brightness without bleaching D.J. Enterprises, Inc., Cleveland, OH, USA Sillum 200 QP... 

ASP072,101,102,170,200,400P, 600,602,672, NC, Buca, Catalpo - hydrous aluminum silicate, spray-dried or highly pulverized powders. ASP 101 is stearate coated and ASP NC is delaminated Santitone 5, 5HB, Special, SP-33, Whitetex - calcinated kaolins... 

Figure 2.35. SEM micrograph of calcinated kaolin. Courtesy of ECC International St Austell, UK.

Typical fillers carbon fiber, glass fiber, aramid, mica, talc, calcinated kaolin, antimony trioxide, carbon black, zinc borate, glass spheres... 

Typical concentration range generally >40 wt% calcium carbonate, calcinated kaolin, talc - 20-40 wt% carbon fiber 5-30% (depending on aspect ratio) " titanium dioxide - 1 wt% (occasionally concentrations of 10 wt% are found in thin sections) " ferromagnetic powder - up to 90 wt% " stainless steel fiber - 2-3 wt% " nickel fibers for magnetic properties -10-30% starch in biodegradable products - 4-8 wt% ... 

In differential thermal analysis, the starch is intimately mixed with a thermally inert materiaP such as calcined kaolin or alumina the mixture is heated at a uniform rate, and the temperature of the mixture is compared with that of a sample of the pure, inert material heated in the identical manner. Any exothermic or endothermic reaction in the starch causes a positive or negative temperature-difference between the two samples this can be recorded, and appears as a positive or negative peak on the resultant thermogram. Differential thermal analysis can be conducted in different atmospheres, such as air, oxygen, or nitrogen, or under vacuum. 

Two other sets of samples have been taken from a recipe for cable insulation and for an ignifugated protective envelope of an electric cable. The recipe for cable insulation includes (in phr) PVC (Kwert 70), 100 ditridecyl phthalate, 34 octyldecyl trimellitate, 17 calcium carbonate covered with stearic acid, 14 calcinated kaolin, 6 dibasic lead phthalate, 8 bisphenol A, 0.05. 

Calcined Kaolin 90-93 0.4-0.7 Steep/ narrow 15-20 Aggregate, low aspect ratio... 

Calcined kaolin, scalenohedral PCC, aragonitic PCC and amorphous silicates are examples of aggregated fillers, i.e. these products consist of crystals which are synthetically clustered into repetitive shapes of similar size throughout the... 

Economic Aspects. The calcium carbonates (calcites, chalks, limestone powders, dolomites, precipitated calcium carbonates, and surface-treated carbonates) account for 80-90 % of the extenders used in Western Europe. In the Federal Republic of Germany calcium carbonates are more predominant than in the remainder of Western Europe (ca. 90%) calcites with a high degree of whiteness and a mean particle size of 2-5 pm are most widely used. Next follow talc, kaolins (with calcined kaolins), silica, barytes, and mica. 

Fig. 1.9. Herreshoff multilevel furnace for roasting ores, calcining kaolin, regenerating carbon, and incinerating sewage sludge. Courtesy of reference 50.

Calcined kaolin Calcined kaolin clay. See Kaolin, calcined... 

The Chemical Abstract Service has defined these materials under the CAS number 142844-00-6 as Refractories, fibers, aluminosilicates. Amorphous man-made fibers produced from melting, blowing or spinning of calcinated kaolin clay or a combination of alumina (AI2O3) and silica (SiOa). Oxides such as zirconia, ferric oxide, magnesium oxide, calcium oxide and alkalines may also be added. 

Calcined alumina. See Alumina Calcined baryta. See Barium oxide Calcined diatomaceous earth Calcined diatomite. See Cristobalite Calcined kaolin Calcined kaolin clay. See Kaolin, calcined... 

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