Aluminization

Cements are commonly made by heating a mixture of limestone and clay to about 1700 C. The product is ground with gypsum. Chemically cements consist of a mixture of calcium silicates and aluminates with some sulphate present. World production 1976 730 megatonnes. 

Loewenstein W 1954 The distribution of aluminum in the tetrahedra of silicates and aluminates Am. Minerai. 39 92-6... 

These equilibria give rise to an acidic solution in water, to the hexahydroxo-aluminate ion [Al(OH)f,]- in a strongly alkaline... 

From the sodium aluminate solution, aluminium hydroxide is precipitated by passing in carbon dioxide ... 

Aluminium oxide is a white solid, insoluble in water, with a very high melting point. If heated above red heat, it becomes insoluble in acids and alkalis, and can only be brought into solution by first fusing it with sodium or potassium hydroxide when an aluminate is formed. 

Salts containing the hydroxoaluminate ions [Al(OH)4(H20)2] and [Al(OH)(i] are known in solution but on heating they behave rather like aluminium hydroxide and form hydrated aluminates. 

The structure of these solid compounds is not known with certainty but an approximate formula might be NaAlOj.xHjO. Many aluminates occur in minerals, for example the spinels of general formula M (A102)2 where M may be Mg, Zn or Fe these have a mixed oxide structure, i.e. consist essentially of M AF and O ions. 

The s)mthesis of zeolites is traditionally performed by crystallisation from a sol-gel mixture comprising reagents such as silica, sodium aluminate, sodium hydroxide and water. Another key component of the sol-gel mixture is a base whose main role is to regulate the pH of the mixture. If an organic base is used then a templating effect may also be observed... 

L. alumen, alum) The ancient Greeks and Romans used alum as an astringent and as a mordant in dyeing. In 1761 de Morveau proposed the name alumine for the base in alum, and Lavoisier, in 1787, thought this to be the oxide of a still undiscovered metal. 

Sillimanite, see Aluminum silicon oxide (1/1) Smithsonite, see Zinc carbonate Soda ash, see Sodium carbonate Spelter, see Zinc metal Sphalerite, see Zinc sulflde Spherocobaltite, see Cobalt(II) carbonate Spinel, see Magnesium aluminate(2—)... 

Aluminous and siliceous residues A 2% hydrofluoric acid solution followed by concentrated sulfuric acid rinse immediately with distilled water followed by a few milliliters of acetone. Repeat rinsing until all trace of acid is removed. 

ALUMDIUMCOMPOUNDS - ALUMINIUMOXIDE(ALUMINA) - CALCINED,TABULAR, AND ALUMINATE CETffiNTS] (Vol 2) -in automobile polishes pOLISITES] (Vol 19)... 

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