Adsorption performance of copper ions on arsenopyrite surfaces and implications for flotation

The removal of arsenic from base-metal ores is an important environmental objective, especially in relation to mineral processing. Herein, we report an investigation into the adsorption performance of copper ions on arsenopyrite surfaces and implications for flotation using local electrochemical impedance and X-ray photoelectron spectroscopies, time-of-flight secondary ion mass spectrometry, zeta-potential measurements, and microflotation experiments. We show that the electrochemical impedance and degree of oxidation of the arsenopyrite decreases as Cu²⁺ is adsorbed onto the arsenopyrite surface, and copper species remain on the surface in the form of Cu(I) following treatment with Cu²⁺, while Cu²⁺ improves the surface charge of the arsenopyrite. A heterogeneously distributed Cu signal appears in the X-ray photoelectron spectrum of the arsenopyrite sample treated with Cu²⁺ ions, and copper in the form of copper sulfide remains on the mineral surface. Microflotation experiments reveal that the low floatability of arsenopyrite in alkaline environments is improved by treatment with Cu²⁺.