High-alumina refractories

High Alumina Refractories. The desired alumina content, from 100% to just above 45%, is obtained by adding bauxites, synthetic aluminosihcates, and synthetic aluminas to clay and other bonding agents. These refractories are used in kilns, ladles, and furnaces that operate at temperatures or under conditions for which fireclay refractories are not suited. Phosphate-bonded alumina bricks have exceptionally high strength at low to intermediate temperatures and are employed in aluminum furnaces. High alumina and mullite are used in furnace roofs and petrochemical apphcations. 

Aluminum chlorite, (Al,Fe)4(Si,Al)402Q(0H)g, in which a gibbsitelike interlayer proxies in part for the bmcitelike interlayer, is being discovered in increasing occurrences and abundance (11,141). Chloritelike stmctures have been synthesi2ed by precipitation of Mg and Al between montmorillonite sheets (143). Cookite [1302-92-7], an aluminous chlorite containing lithium, has been found in high alumina refractory clays and bauxite [1318-16-7] (139). 

High alumina brick, ASTM classifications and specifications for, 21 508 High alumina catalysts, 11 724 High alumina refractories, 21 515, 518 High analysis fertilizers, 11 123, 124 High aspect ratio micromachining... 

MgO-spinel clinker is obtained by the same procedure, but with a substantial proportion of free MgO (75-85%). MgO-spinel is produced by sintering at temperatures of 1600-1800°C and a dense product is obtained. MgO-spinel refractory has better high temperature mechanical properties in arc furnace roof application compared to magnesia-chrome refractories, but it has lower strength than a high-alumina refractory. 

W.V. Ballard and D.E. Day, Stability of the refractory-bond phases in high alumina refractories in steam-CO atmospheres, Ceram. Bull., 57 [7] (1978) 660-666. 

Table 18-1 Approximate Pyrometric Cone Equivalent (PCE) Values of Generic Classes of Fireclay and High Alumina Refractory Brick...

The annual world production of refractories is about 25 million tons. About 60% of this is consumed in metallurgy, the rest in the glass and cement industries, etc. The following shares of the individual types were reported for the late sixties 70% fireclay and high-alumina refractories, 17% basic refractories, 8% silica refractories and 5% other products. 

Alcan C Series. [Alcan] Calcined alumina raw material for mfg. of fused alumina abrasives, high alumina refractories, ceramic fibo insulation, hot tqpping compds., hits, glazes in abrasives, polishes as catalyst sunxMt. 

The phosphate-bonding techniqne has proved most successful with alumina or high-alumina refractories, using H3PO4 or A1(H2P04)3 as bonding agents. The reaction of the latter can be represented as... 

ASTM C-24 Pyrometric cone equivalent of fireclay and high-alumina refractory materials... 

Utah), Mexico, Italy, Egypt, and elsewhere. The residue obtained after calcination and leaching out of the alkali can be used as raw material for high-alumina refractories. 

Charp. Trade-name for Calcined High-Alumina Refractory Powder it is made from Ayrshire bauxitic clay. 

High-alumina Refractory. A refractory of the alumino-silicate type. In the UK it is defined in B.S. 3446 as containing over 45% AI2O3. In the USA seven classes of... 

High-alumina refractory 40-300 Carbon refractory 130-160 Magnesite refractory 160-300 Silica refractory 200-300 Morphology. The study of size, shape and texture of particles and particle compacts. B.S. 2455,1958 defines a variety of particle shapes ... 

Top Pouring. See direct teeming. Topaz. Al2Si04(0H,F)2. Occurs in economic quantities in Australia, Brazil, Nigeria and USA. After it has been calcined, the material has a composition similar to that of mullite and it has been used to a small extent, either alone or mixed with calcined kyanite, for making high-alumina refractories. 

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