Alumina alum process

Fig. 4. Synthesis of the alumina abrasives using the alum process. (Courtesy of Baikowski International Corp., Charlotte, NC.)...

This process is currentiy used by Vista Chemical, successor to Continental Oil Company s chemical business, and by Condea. In the Ethyl Corporation process dilute sulfuric acid is used in place of water in the hydrolysis step producing alum rather than alumina. 

The large majority of activated alumina products are derived from activation of aluminum hydroxide, rehydrated alumina, or pseudoboehmite gel. Other commerical methods to produce specialty activated aluminas are roasting of aluminum chloride [7446-70-0], AIQ calcination of precursors such as ammonium alum [7784-25-0], AlH2NOgS2. Processing is tailored to optimize one or more of the product properties such as surface area, purity, pore size distribution, particle size, shape, or strength. 

The most common technique used to prepare the /i-type (i.e., or / ") alumina is to mechanically blend the component oxides or precursor compounds in powder form prior to a calcination or prereaction step at temperatures between 1000 and 1260°CT Commercially available aluminum oxide powders (0.3-0.5 pm average crystallite size) in the alpha (corundum) polymorph are typically usedT They are derived from three common sources decomposition of gibbsite [Al(OH)3], which is precipitated from soda liquors in the Bayer process preparation and decomposition of alum salts and preparation from aluminum chloride precursors NaaCOs is usually the source of Na20. Sources of Li20 have included Li2C03, LiNOs, and Li2C204- MgO is usually added as the commercially available oxide. 

The cost of capital equipment for a Bayer processing plant is related to the amount of monohydra ted alum ion present (boehmice or diaspore) and to the amount of iron oxide present. The first relates lo the refractory nature of ore and the second to the amount of material that must be handled and separated, Hill and Robson14 have estimated capital cost ratios for Bayer plants lreeling various types of bauxite ore. Capital costs of a bauxite containing 50% of the alumina as the mono hydrate are estimated to be 40% higher IhBn for a typical low-cost beuxite. 

Western-world bauxite production in 1988 totaled about 90 x 10 t, approximately 90% of which was refined to aluminum hydroxide by the Bayer process. Most of the hydroxide was then calcined to alumina and consumed in making aluminum metal. The balance, which constituted about 2.3 x 10 t in 1988 (Table 2), was consumed in production of abrasives (qv) adhesives (qv) calcium aluminate cement used in binding ceramics (qv) and refractories (qv) catalysts used in petrochemical processes and automobile catalytic converter systems (see Petroleum Exhaust control, automotive) ceramics that insulate electronic components such as semiconductors and spark plugs chemicals such as alum, aluminum halides, and zeoHte countertop materials for kitchens and baths cultured marble fire-retardant filler for acryhc and plastic materials used in automobile seats, carpet backing, and insulation wrap for wire and cable (see Flame retardants) paper (qv) cosmetics (qv) toothpaste manufacture refractory linings for furnaces and kilns and separation systems that remove impurities from Hquids and gases. 

Formuia Al2(OH)nCI, n = 1-5 Uses Coagulant and flocculant for industrial water, wastewater, potable water treatment, sewage/plant effluent treatment, paper processing applies. alum replacement in alkaline papermaking processes fire-resist, ceramic paste binder alumina fiber raw material catalyst raw material textile finishing agent food-contact applies. 

Polyaluminum hydroxide chloride sulfate alum substitute, neutral sizing process paper Polyaluminum hydroxide chloride sulfate alumina fiber raw material Polyaluminum chloride alumina mfg. 

Discovery In 1825 H. C. Oersted in Copenhagen prepared the element aluminum for the first time. Between 1827 and 1845, Friedrich Wohler improved Oersted s process. In 1886 Charles M. Hall and Paul H roult independently developed the method for aluminum manufacture by electrolysis of fused salts, a technique now known as the Hall-H4roult process. The element s name has its own history. In 1761 de Morveau proposed the name alumina for the base in alum. The name aluminium was adopted by lUPAC to conform to the ium ending of most elements. Aluminum is the lUPAC spelling, and therefore the international standard. In 1925 the American Chemical Society decided to change the name to aluminum, still used in American literature and technical descriptions. 

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