Improved activation of malachite sulfurization flotation by thiourea's (CS(NH2)2): Performance and mechanism study

Abstract

In this study, thiourea (CS(NH₂)₂) was an effective activator for promoting the sulfurization flotation of malachite. The flotation behavior of malachite in the presence of this activator was investigated. Experimental results revealed that thiourea is a superior activator for malachite sulfurization, achieving a recovery rate of over 89 % at appropriate dosages. Thiourea-sulfurized malachite forms a surface layer of copper(I) thiocyanate, which facilitates the reduction of Cu(II) to Cu(I) species, leading to the generation of more Cu(I)−S species. These species adsorb more readily onto the malachite surface compared to Cu(II)−S species. The robust layers consist of SCN¯ ligands that combine with copper(I) complexes to form CuSCN species during sulfurization. This enhances malachite surface sulfurization, resulting in higher flotation recovery. Further analysis using ToF−SIMS, FESEM−EDS, and XPS confirmed that thiourea likely chemisorbs onto the malachite surface through sulfurized malachite. The activation mechanisms and the presence of N-atoms in the XPS spectra verified that N−H, C−N, and Cu−N bonds were chemisorbed and formed on the surface, significantly improving the hydrophobicity of sulfurized malachite. This work has important implications for the future application of thiourea activation in flotation processes and could contribute to developing environmentally friendly solutions to meet consumer demand.