Development of Waelz-Oxide Hydrometallurgical Processing Technology with Preparation of Carbonized Lead Cake

Comprehensive processing of ore and technogenic raw material containing zinc and lead requires improvement of lead-containing product quality provided by zinc industry enterprises for lead extraction by a pyrometallurgical method. Research and development are conducted for Waelz-oxide pyrometallurgical treatment technology with preparation of carbonized lead cake containing more than 45% lead, not more than 5% sulfur, and with a moisture content after filtration less than 35% suitable for black lead preparation in short-drum kilns with good technical and economic efficiency. Carbonization and pyrometallurgical treatment of carbonized lead cake make it possible to reduce soda consumption and sulfur compound concentration considerably in waste gases. Introduction of contemporary technology for preparing Waelzprocess charges drawing on treatment of copper production zinc- and lead-containing dust, and also optimizing process parameters for cake preparation and carbonizing make it possible to increase the lead content in carbonized cake from 40–43 to 46–50%. In order to resolve the problem of increasing lead content and reducing lead cake moisture content, filtered in filter-presses, research is conducted in the course of which the phase composition of sulfate and carbonized products and thermal effects proceeding during carbonized cake drying and heating are studied. Optimum parameters are determined for introducing the technology on the bases of industrial tests. Washing lead sulfate cake before carbonization makes it possible to increase the lead content by 2–4% in carbonized cake. A reduction in pH during lead cake carbonization from 8.5–9.0 to 7.0–7.5 makes it possible to reduce the filtered product moisture content from 35–36 to 27–30%.