Desulfurization of Cu–Fe Alloy Obtained from Copper Slag and the Effect on Form of Copper in Alloy

Abstract

In order to realize the high-value utilization of copper slag, a process for preparing Cu–Fe alloy through the reduction of copper slag is proposed. The sulfur in the alloy exists in the form of matte inclusions, which is different from sulfur in molten iron. The reaction of CaO with Cu2S is difficult. It is necessary to add a reducing agent to promote desulfurization. To avoid the introduction of other elements, Fe‒Mn and CaC2 additions were used as desulfurizers for the desulfurization of Cu‒Fe alloy. The thermodynamics of the desulfurization reaction were calculated and the experimental process was studied. It was found that the Gibbs free energy of desulfurization reactions was negative for Fe‒Mn and that CaC2 can reduce the sulfur in the alloy to 0.0013% and 0.0079%, respectively. The desulfurization process affected the shape of copper in the alloy. Part of copper in this alloy exists in the form of nano-copper spheres, and the size of the spheres is found to increase after desulfurization. Reducing agents can facilitate the desulfurization process of stable sulfides.