| 摘要 |
<p>Particulate ores, concentrate and mixtures thereof containing iron and cobalt-sulphur-arsenic complex minerals are treated to recover the cobalt by oxidizing an aqueous sulphuric acid slurry of the particles with air, oxygen-enriched air or oxygen at temperatures of 250 DEG F.-650 DEG F. and super-atmospheric pressure, the acid content of the solution being maintained less than 10 per cent. by weight but greater than that corresponding to a pH greater than 4.5. Mutually equivalent amounts of iron and arsenic are precipitated as acid insoluble arsenate leaving cobalt in solution as sulphate, from which it may be recovered in a known manner. Where the treated liquid still contains dissolved arsenic, this may be precipitated before or after separation of p the solid residue by addition of acid soluble alkaline earth compound such as limestone or dolomite or iron, e.g. in the form of pyrites, to produce a pH not more than 4.5 to remove arsenic as calcium, magnesium or iron arsenate. The resulting liquid will contain, in addition to cobalt, other acid soluble metals such as copper, nickel, zinc and silver. Copper may be precipitated as metal, by cementation, or by treatment with carbon monoxide or hydrogen, or as sulphide, by addition of an alkali metal sulphide or ammonium sulphide. Cobalt sulphate in relatively pure form may be obtained by partial crystallization and separately treated or cobalt and nickel may be separated by addition of ammonia to give a pH of 4.5-6.7 at which nickel sulphate-ammonium sulphate crystals are precipitated leaving cobalt in solution. Cobalt is recovered by addition of ammonia to give a pH of above 6.8 to convert the cobalt ions to the complex Co(NH3)xxx ions, x being 2-6, and reducing at elevated temperature with a reducing gas such as hydrogen. Specifications 728,135 and 728,136 are referred to.ALSO:Cobalt and nickel recovered separately in the form of solutions of their sulphates (see Group III) are precipitated in metallic form from solution in the following manner. Cobalt sulphate solution is treated with ammonia to give a pH of above 6.8 to convert cobalt ions to complex CO(NH)x++ ions, where x is 2-6 and is reduced with a gas such as hydrogen at 425-500 DEG F. at superatmospheric pressure, cobalt being precipitated as powder. Nickel sulphate solution, similarly treated with ammonia, is reduced at 350-450 DEG F. Carbon monoxide may be used instead of hydrogen. Specifications 728,135 and 728,136, [both in Group III], are referred to.</p> |
