Effect of coke content on element migration and product structure during reduction matte smelting of arsenic-rich lead-bearing solid waste

The safe disposal and resource recovery of arsenic-bearing solid waste represent a critical challenge for the sustainable development of the metallurgical industry. High-temperature reduction matte smelting offers a promising route for simultaneously stabilising arsenic and recovering valuable metals. However, the precise mechanistic role of coke in influencing reaction pathways and product characteristics remains poorly understood, hindering process optimisation. This study systematically investigates the effect of coke addition (0∼6 %) on the migration of key elements (Pb, As, S) and the phase composition of the products. Results indicate that an optimal coke dosage (1∼2 %) promotes clear product layering and significantly enhances lead reduction and enrichment, with grades of 90.12% (C1) and 93.11% (C2), accompanied by high recovery rates of 92.07% and 89.59%, respectively. Moreover, it effectively stabilises arsenic and sulfur within the iron-rich matte, with fixation rates exceeding 95% and 88%, respectively. Conversely, excessive coke (≥3%) increases melt viscosity and induces vigorous gas evolution, which hinders effective phase separation, leading to the formation of unreacted powders and dispersion losses of lead. This work elucidates the dual role of coke in the reduction matte smelting process, providing crucial theoretical insights and key parameters for the green and resource-oriented treatment of arsenic-bearing solid waste.