Patent GB-778266-A (GB)
Title: Improvements in or relating to the production of alumina
IPC: C01F7/428
Filed: 1955-05-23
Abstract: Particles of metallic aluminium are reacted with liquid water by agitating in the presence of mercury or a murcury compound as catalyst and a water-soluble surface active agent to produce alumina. It is preferred to use substantially pure aluminium since the presence of alloying elements inhibits the reaction. The temperature of the reaction may be from -1 to +374 DEG C., preferably to +205 DEG C., pressure being applied if necessary, and 0.01 to 5 per cent. by weight of the water of surface active agent may be used.  Increased qualities of surface active agent result in general in increased surface area of the alumina formed.  The catalyst may be used in a proportion of 0.05 to 50 per cent. by weight of the aluminium.  Bases and acids are referred to as promoters, and details are given of the production of gels and sols.  In the production of gels, acids such as hydrogen fluoride, chloride, bromide and iodide and also nitric, sulphuric, phosphoric, oxalic, malonic, succinic, maleic, tartaric and citric acids are specified, and it is stated that at least 0.01 equivalents of any acid anion per equivalent of aluminium should be used and for monobasic inorganic acids below 0.13 equivalents of acid anion per equivalent of aluminium should be used whilst the corresponding figures for bivalent inorganic and polyvalent acids in general are 0.5 and 1.0 respectively, although figures up to 5.0 may be used in some cases.  For sol formation, similar inorganic acids are specified and the corresponding figures lie within the range 0.13 to 0.75, monobasic acids being used in the lower and bivalent acids in the upper part thereof.  Above 205 DEG C., crystals are produced. By drying a gel at -1 to 205 DEG C., Gibbsite is produced, at up to 343 DEG C., Bohmite is formed.  The specified surface active agents fall into the following groups and examples are given (1) polyalkylene ethers of alkyl phenols in which the alkyl group contains from 4 to 12 carbon atoms per group and containing from 5 to 25 oxalkylene groups per molecule.  (2) Polyalkylene ethers of hexitans and hexides derived from sorbitol and particularly the polyethylene ethers thereof.  (3) Polyalkylene esters of alkylphenyl carbamic acids in which the alkyl group contains from 6 to 18 carbon atoms per group and the ester radical contains from 10 to 150 polyoxyalkylene groups per molecule.  (4) Polyalkylene glycol esters of long chain fatty acids particularly mono- and di-fatty acid esters.  (5) Polyalkylene glycols containing from 50 to 150 polyoxyalkylene groups per molecule, and the partial esters of polyglycerol.  (6) The fatty acid esters of hexitans and hexides derived from sorbitol.  (7) Sulphated fatty acid esters particularly glycerides of saturated fatty acids such as castor oil and coconut oil.  (8) The polyalkanol amine salts of alkylarylsulphonates in which the alkyl groups contain from 9 to 18 carbon atoms per moleceule.  (9) The amine salts of carboxylic acids, particularly alkylamine and alkanol amine salts of succinic and sulpho-succinic acids.  It is preferred to use a volatile agent free from metallic constituents; in this case it is unnecessary to wash the alumina before drying &c.  Specifications 769,026 and 769,217 are referred to.