Abstract
Selective extractions of gold chloro complex from the chlorine leach liquor of copper anode slime with dibutyl carbitol and selective reduction of gold in the organic phase with oxalic acid were investigated.
The reduction process is the most important step for the impurities removal in gold. In the reaction, since the stability of chloro complex of silver and platinum group metals increases with chloride ion, reductions of these ions are controlled. Hydronium ion generated in the reaction is effectively neutralized by hydrolysis of urea without local increase in pH value and local decrease in ORP (Oxidation Reduction Potential). In the result, co-precipitations of most impurities (Ag, Se, Sn, Sb, Pt, Pd, Fe) in the gold powder were suppressed.
