Green production of Fe–Cr–Cu master alloys via electric smelting of pre-reduced briquettes prepared from copper slag and chromite

Copper slag not only exacerbates environmental risks associated with heavy metals due to its annual accumulation in the tens of millions of tons but also highlights the deep-rooted challenges faced by industrial civilization in the context of resource recycling systems. This study presents a green process for producing Fe-Cr-Cu master alloys through the electric smelting of pre-reduced briquettes made from copper slag and chromite. Thermodynamic analysis, a multi-parameter coupled optimization experimental system, was used to systematically explore the migration behaviours of metal elements and slag phase regulation mechanisms in the smelting process. The results indicate that with a smelting temperature of 1600°C, a duration of 80 minutes for smelting, a briquet basicity of 0.6, and a coke ratio of 6 wt.%, the recoveries for Fe, Cr, and Cu were recorded at 98.93%, 96.23%, and 95.56%, respectively. The produced Fe-Cr-Cu master alloys with 74.98 wt.% Fe, 17.01 wt.% Cr, and 1.23 wt.% Cu was achieved. Alloy inclusions within the slag phase were measured to be less than 0.5 μm in size, exhibiting a distribution density of roughly 1 per/mm 2 . This study proposes a viable “waste as a substitute for ore” strategy for the valorization of copper slag, offering a practical solution to the critical issues of resource depletion and pollution. Moreover, the developed Fe-Cr-Cu alloys serve as a high-quality burden for copper-containing special steels, which can shorten its flowsheet of production and save energy consumption.