SOLVENT EXTRACTION MIXTURE COMPRISING SUBSTITUTED IMIDAZOLE OR BENZIMIDAZOLE FOR THE PURIFICATION OF BASE METALS

摘要

This invention provides an organic solvent extraction mixture for the purification of base metals which includes: a) a first extractant, which is a substituted imidazole (Diagram 1) or benzimidazole (Diagram 2) and wherein the substituents are: R1 = an organic group which has between 2 and 20 carbon atoms, preferably between 6 and 15 carbon atoms; R3 = a hydrogen atom or a short chain organic group with 1 or 2 carbon atoms, preferably hydrogen or a methyl group; R4 = a hydrogen atom or a short chain organic group with 1 or 2 carbon atoms, preferably hydrogen or a methyl group; R2 = a -2-pyridine group in which the pyridine group can be substituted or unsubstituted; or = a -methylene-1-pyrazole group in which the pyrazole group can be substituted or unsubstituted; or = an imidazole based group, which may be a mirror image of the compound shown in Diagram 1 or 2; or = a methylene-amino group as shown in Diagram 3; b) a non selective strongly acidic cation second extractant, such as a sulphonic acid (R-SO2H), to facilitate phase transfer of base metal ions from aqueous weakly acidic sulphate solution into the organic phase, and wherein R is an aliphatic group, either saturated or unsaturated and branched or unbranched, an aromatic organic group or a mixed group consisting of aliphatic and aromatic parts, with between 3 and 40 carbon atoms, preferably with between 8 and 30 carbon atoms; c) a modifier to improve the characteristics of the organic phase with respect to metal complex solubility to avoid third phase formation, completeness and ease of stripping, viscosity and phase disengagement; and d) a diluent, which is selected from a non-specific aliphatic or aromatic or partly aliphatic, partly aromatic mixture of unspecified composition with moderate boiling point range and a suitable flash point, such as Kerosene, Shellsol (various grades), Escaid (various grades), Solvesso and similar products.