Processing of metallurgical dusts in sulfate-nitrate solutions

Abstract

The composition of fine dusts of copper smelting enterprises contains zinc, copper, lead, which are of practical interest for their subsequent use in metallurgical processing, and arsenic, which is the main impurity and requires purification. For the processing of polymetallic middling products, various physicochemical processes are used — pyrometallurgical, hydrometallurgical, electro-chemical, having both advantages and disadvantages. One of the promising ways to extract valuable components into a solution, followed by selective conversion to cognominal products, is the considered sulfur — nitric acid technology. The implementation of such a scheme allows not only to achieve a high degree of extraction of valuable components from dust, but also to obtain monocomponent products suitable for further processing with the production of pure metals. Under laboratory conditions, regularities in the recovery of non-ferrous metals from the consumption of nitric acid were determined. The main parameters of the processing of metallurgical dust according to the sulfuricnitric acid scheme were selected. Experiments on sulfur-nitric leaching were carried out at a sulfuric acid concentration of 100 g/dm3, temperature 80 оC, L:S = 1:3 ratio, duration 3 hours, consumption of nitric acid varied from 0 to 0.7 g/g. The proposed technology allows in one stage to obtain Zn – As – Cu solutions that are suitable for processing with receiving individual products. The scheme provides for the return of nitrate-containing solutions to the leaching of sulfide material, which significantly increases the utilization rate of nitric acid. The main operations of the technology are: neutral leaching, sulfuric acid leaching, nitrate leaching, arsenic precipitation, copper precipitation as sulfide with return of part of Cu – As cake for conditioning it by copper and removal of arsenic. On the basis of the conducted research, the optimal parameters for the processing of metallurgical dusts for the selective separation of copper, zinc, lead and arsenic were established.