Comparison of germanium recovery from copper(II) sulfate-based solution using tertiary amine and oxime extractant

Germanium is considered by many world economies, including the USA and EU, as a critical raw material. One of the methods, which may be used in its recovery is solvent extraction. Using it application of more environmentally harmful processes like tannin concentrate precipitation or chlorination may be reduced. Solvent extraction of germanium from solution after oxidative leaching of copper cake by two extractants, chelating Mextral 63H (LIX 63 equivalent) and basic trioctylamine (TOA), were compared. For TOA influence of complexant addition, tartaric acid, malic acid, malonic acid, and succinic acid, on germanium recovery yield was also tested. It was found that under investigated conditions, i.e. pH∼1.0 TOA was a better and more selective germanium extractant. The highest Ge extraction yields (>96 %) were achieved when tartaric acid was used as a germanium complexant in an aqueous phase. It was determined that germanium may be stripped from the organic phase using > 5 wt% NaOH solution with > 93 % yield.