| 摘要 |
<p>An aqueous Ni solution is purified by extracting metal contaminants with at least one water-insoluble quarternary ammonium chloride, iodide, bromide, nitrite, azide, tungstate or molybdate; primary or secondary amine chloride, iodide, bromide, azide, or thiocyanate; or tertiary amine thiocyanate alone or mixed with the chloride; with or without a quaternary ammonium thiocyanate; preferably in a water-immiscible organic solvent. The amine salt may be formed in situ using free amine. The quaternary ammonium compound preferably contains at least 2 alkyl chains having 8 or more carbon atoms attached to the N atom. The primary, secondary, and tertiary amines may have alkyl groups containing 18-22, 12, and 8-10 carbon atoms respectively. The solvent may be methyl isobutyl ketone, mixed xylenes, e.g. kerosene, and/or alcohols, containing the salts at 0.1-1.25 M concentration, and may be used in amounts of 1 part per 10-20 parts of the Ni solution. Quaternary ammonium chloride is used to remove Co, Zn, Fe3+, Pb and Cu; the iodide to remove Zn and Pb; and the tungstate or molybdate to remove As. The organic phase is stripped of impurities by treating with an alkali metal hydroxide, a sulphide, NH3, (NH4)2CO3 or soda ash, and the organic extractant recycled. The aqueous Ni solution is treated to remove anions (Cl1, Br1 &c.) by adding an amine salt in an organic solvent, treating the resultant organic amine salt solution with alkali, e.g. KOH, NaOH, NH3, (NH4)2CO3 or Na2CO3 to re-extract anions into the aqueous phase, and returning this solution to the first stripping of the organic phase. Alternatively, I1 and Br1 may be removed by precipitation as the cuprous salt.</p> |
