D. Mendeleev University of Chemical Technology of Russia, Moscow, Russia:

A. A. Krasnoshtanova, Professor at the Department of Biotechnology, Doctor of Chemical Sciences, e-mail: aak28@yandex.ru
V. I. Panfilov, Head of the Department of Biotechnology, Doctor of Engineering Sciences, Professor

Copper is among the most important non-ferrous metals produced on industrial scale. The main source of copper is ore which is mined around the world. The concentration of copper in ore is relatively low and, by various estimates, varies between 0.3 and 5.0%, and the share of ores with higher concentrations of copper is gradually shrinking. Bioleaching provides one of the most innovative alternatives to conventional physical and chemical beneficiation techniques because it consumes less resources and is more environmentally friendly. The aim of this research is to understand the efficiency of using separate aminoacids and the protein hydrolysates from yeast to extract copper from low-grade ores. The material of study included waste ore from the Volkovsk deposit ground to 2–3 mm and containing 1.0% of copper. The following aminoacids were applied for copper recovery: phenylalanine hydrochloride, glycine hydrochloride, serine hydrochloride with the minimum concentration of the parent substance of 98%. These aminoacids are made by Biochem, France. The protein hydrolysates were made from the baker’s yeast Saccharomyces cerevisiae containing 52% of whole protein and 5.8% of nucleic acid. The following dissolution process proved to be efficient for copper contained in lowgrade ores: 0.1 mol/l sodium chloride, 0.05 mol/l of glycine and aspartic acid, temperature 80 ^oC, duration 15 hours. The minimum degree of copper dissolution reached is 90%. The authors prove the applicability of protein hydrolysates from yeast with the minimum concentration of amine nitrogen of 65% as a complexing agent that can deliver a minimum copper recovery of 92% in the following conditions: concentration — 0.05 mol/l, temperature — 50 ^oC. It was established that the ability of protein hydrolysates to interact with copper ions is attributed to the aminoacids contained in them, and namely due to high concentrations of aspartic acid and glycine.

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