The cathode sediments (CS), obtained as a result of industrial processing of gold-polymetallic raw material with complex chemical and mineral composition, contain a significant amount of impurity metals (copper, lead, zinc, iron, etc.), which leads to a significant increase in the cost of subsequent refining of these materials. The authors carried out experimental work on preliminary acid treatment of CS for the purpose of leaching impurities and increasing the share of precious metals in them. The objects of research were cathodic sediments (bypass solutions of the enterprise) containing copper and lead in the amount,% wt., respectively: 21.29 and 4.11. We tested nitric acid as a solvent in laboratory tests. For the selection of optimal leaching parameters, studies were carried out at various concentrations of the agent (from 50 to 350 kg/m3) and the ratio of L:S - (3-7):1. The duration of the experiments was 2 h, the experiments were carried out with vigorous stirring and standard ambient temperature (25°C). The experimental data processing was carried out with the help of STATISTICA 6.0 software; As factors of variation, we chose: concentration of acid, ratio of liquid and solid phases. It has been determined that nitric acid provides effective purification of CS from impurities. After the chemical enrichment, the content of precious metals in leaching cakes increased, the CS became compliant with the requirements of TU 117-2-3-78. When processing cathode sediments with nitric acid, 99% of silver passes into solution, which then allows it to be recovered from solutions by cementation and, consequently, to obtain alloys of gold and silver separately.
