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This article provides an overview of the Kivcet technique in Jiangxi Copper Corporation, reviews the production status and problems encountered in the past decade, introduces its technological advantages and prospect. It is believed that the Kivcet process has advantages such as strong adaptability to raw materials, stable operation, high metal recovery rate, and low cost of zinc leaching residue treatment, which is the vitality of lead-zinc smelting enterprises in the future.

Nowadays, co-processing iron precipitates and other zinc hydrometallurgical residues with lead concentrate is widely implemented due to the emphasis on sustainable development. However, when a significant amount of goethite residues was treated in a Kivcet furnace, a new “sticky slag layer” composed of spinel, oxides, and metallic lead formed between the lead bullion and molten slag, which caused operational challenges including slag tapping difficulties, high energy consumption, and low Pb recovery rate. In this study, single-particle experiments were conducted to investigate the phase transformations and reaction mechanisms of goethite residue particles in the flash smelting process. The phase transformations of Fe-, Zn-, Al-, Si-, Ca-, and S-bearing species were resolved, and the effects of particle size and processing temperature were evaluated. The reaction mechanisms of initial fine particles and coated particles were specifically identified. The findings demonstrated that Zn and Al content in goethite residues increased with particle size, whereas Fe content decreased. Initial fine particles aggregated together with liquid phases at high temperatures, while initial large particles fragmented due to the release of SO 2 from within them. Sulphates decomposed into oxides, which quickly formed spinel phases including ZnO·Fe 2 O 3 , ZnO·Al 2 O 3 , and FeO·Fe 2 O 3 , and the amount of spinel increased with temperature. Additionally, the spinel always formed on the surface of large ZnO particles, producing spinel coating particles. The generation of the stable spinel phases was found to be a major contributor to the sticky slag layer. Controlling Fe, Al, and Zn content in the feed is essential to prevent this issue. Graphical Abstract

The prediction of phase configurations and the optimization of operating parameters in the metallurgical process are normally achieved by the multiphase equilibrium calculation (MEC), which is formulated as a constrained optimization problem based on the principle of Gibbs free energy minimization. A revised quantum-behaved particle swarm optimization (RQPSO) algorithm has been proposed to solve the optimization problem using three-part improved strategies. Based on the KIVCET smelting characteristics, a MEC model for the KIVCET process is established and solved using the RQPSO algorithm. The calculated and industrial data of the lead grade are 96.20% and 96.33%, respectively, those of the matte grade are 19.39% and 19.68%, and the mass fractions of Pb in the predicted and industrial matte are 3.96% and 3.34%, respectively. The calculated results of the phase configuration are consistent with the actual production data, which indicates that the MEC model and RQPSO algorithm are accurate and reliable.