Chalcopyrite leaching by amino acid solutions in the presence of hydrogen peroxide

It is demonstrated that amino acids such as glycine, betaine, and lysine may be applied as selective copper leaching agents in the process of hydrochemical oxidation of chalcopyrite at atmospheric pressure and in the temperature range 25÷65°C. The advantage of the proposed method is its relative environmental friendliness. Solid samples of the initial mineral and leached chalcopyrite residues were analyzed by X-ray diffraction analysis, and Mössbauer and Raman spectroscopy. The results of the atomic absorption analysis showed that copper's extraction efficiency increased when the experiment's duration was raised and when the process temperature was higher. The leaching ability of amino acids was evaluated by the specific leaching rate of chalcopyrite in these reagents. Amino acid leaching was thought to be mainly due to the complexation of copper (II) glycinates, copper (II) betainates and copper (II) lysinates. This reaction can be enhanced by adding hydrogen peroxide to the system as an oxidant. It was determined that glycine was more effective as a leaching agent than betaine and lysine. Based on experimental data, it was assumed that the most possible mechanism is selective copper leaching due to the formation of chalcopyrite-based solid solution Cu1-xFeS2.