Abstract
Problem Statement (Relevance): This article examines the possibility of creating an environmentally friendly, technologically efficient and cost-effective high-performance reprocessing technology for lead-containing middlings and wastes. Using the example of the pyrometallurgical technology of reduction smelting applied to lead cake (~35% Pb) and silicate slag (~22 % Pb), the authors describe the current problems related to the optimization of traditional methods used in complex processing of polymetallic middlings from waste, with non-ferrous metals being turned into marketable products through computer simulation. Objectives: This study aims to look at how the phase composition and the element distribution depend on the primary charge composition, as well as to analyse the possibility of using a thermodynamic study for identifying the optimal composition of the charge used for reduction smelting of lead саke at the site of Electrozinc OJSC (Vladikavkaz) and of silicate slag. Methods Applied: With the help of Outotec’s HSC Chemistry software package, balance calculations were performed for multicomponent equilibrium compositions in a heterogeneous gas–liquid–solid system during the reduction smelting of lead cake and silicate slag. Originality: The original features of this research include simultaneous smelting of lead cake and silicate slag and the use of metal shavings and iron ore, together with coke, as reducing agents, which enable the disposal of industrial waste. Findings: In the process of reduction smelting, it is primarily zinc that reacts to transform into gas, whereas lead, copper and antimony are concentrated within the metal phase. With the optimal composition of the charge, %: 67 – lead саke; 9 – silicate slag; 2 – iron turnings; 3 – limestone; 12 – coke; lead, copper (>99%), most of the antimony (>88 %) and arsenic (>78%) almost completely transform into the metal phase; zinc, together with oxidized iron (~54%), is distributed between the gas phase (~67%) and the speiss-slag phase (~31%). Practical Relevance: Initial data were obtained for optimized reduction smelting of polymetallic wastes and middlings. This will enable to expand the range of lead-containing materials that can be used in end-to-end pyrometallurgical processing to produce marketable products from non-ferrous metals.
Keywords
Melting, cake, mixture, sublimates, slag, matte, metal, lead.
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