Antimony Extraction from Sulfide Concentrates by Direct Electrolytic Desulfurization in Molten Salt

Abstract

Recognizing the imperative to address global climate change and promote sustainable development within the industry, the conventional antimony smelting process, characterized by high energy consumption and pollution, is confronted with escalating ecological and environmental pressures. This study proposes a two-stage method for the efficient and thorough extraction of antimony through direct electrolysis from sulfide concentrate in molten salt. Our focus is on assessing the technical feasibility and cost advantages of directly electrolyzing antimony concentrates for industrial applications. The study commences with an analysis of the pyrolysis and electrolytic desulfurization behaviors of each component through thermodynamic calculations. Subsequently, it investigates the effects of various factors on product quality and electrolysis stability during the first stage (constant-current high-efficiency electrolysis) and the second stage (constant-voltage deep electrolysis), respectively. The study also examines the flow of elements and the desulfurization mechanism, while evaluating the economic and environmental impacts of the process. The results demonstrate that the two-stage combined electrolysis process can meet the requirements of high efficiency and continuity of electrolysis, achieving a remarkable integrated current efficiency of 80%, electrolysis energy consumption of 2.39 kWh·kg–1, and a direct antimony yield of 97.11%. In comparison to the traditional process, this novel method of antimony extraction through molten salt electrolysis reduces energy consumption, carbon emissions, and production costs by 72.06%, 95.76%, and 48.59%, respectively. Furthermore, sulfur is obtained directly without the emission of SO2. This work not only provides theoretical guidance and technical ideas for the green electrolytic desulfurization of antimony sulfide but also extends its applicability to other sulfide concentrates such as CuFeS2, PbS, ZnS, WS2, MoS2, and Bi2S3.