Manufacture of wear-resistant cast iron and copper-bearing antibacterial stainless steel from molten copper slag via vortex smelting reduction

Abstract

A novel method of preparing wear-resistant cast iron and copper-bearing antibacterial stainless steel by moderate dilution of molten copper slag and vortex smelting reduction is proposed in this paper. The reduction behaviors of different components during vortex smelting reduction after medium dilution of molten copper slag are systematically investigated. Thermodynamic analysis results show that lime (CaO) can promote the decomposition of the iron peridotite phase and strengthen the reduction of copper and iron in slag. Under the conditions of 1450 °C, slag alkalinity of 1.0, 0.13 wt% carbon addition, vortex stirring speed of 250 rpm, and sedimentation stirring speed of 63 rpm, the metallization rate of copper and iron is 91.76%. In addition, 97.90 wt% zinc and 14.79 wt% lead in copper slag enter flue gas to be recovered, and 94.11 wt% silver and 88.66 wt% gold are reduced into metal. HBW555Cr13 wear-resistant cast iron and 20Cr13Cu3 copper-bearing martensitic antibacterial stainless steel, which meet the requirements of Chinese national standards, are successfully prepared by this process, realizing the separation, enrichment, and recovery of valuable components in the copper slag. The Brinell hardness of wear-resistant cast iron is 575, and the antibacterial rate of copper-containing antibacterial stainless steel against Escherichia coli is more than 99%. The reduction slag can be used as the raw material for preparing cement clinker after water quenching. There is no secondary waste residue, which realizes the molten copper slag's large-scale, slag-free, and high-value utilization.