Colloidal ZnCO₃ as a Powerful Depressant of Arsenopyrite in Weakly Alkaline Pulp and the Interaction Mechanism

Abstract

The effects of ZnSO4 on arsenopyrite depression were studied with sodium carbonate and sodium isobutyl xanthate (SIBX) as the pH regulator and collector, respectively. In both micro and real ore flotation tests, ZnSO4 showed better depression on arsenopyrite (pH 7.5–9.0 adjusted by Na2CO3) compared with sodium humate. The depression mechanism of ZnSO4 on arsenopyrite flotation was studied by electrokinetic potential, adsorbed amount measurements, scanning electron microscope (SEM) observation and energy dispersive spectra (EDS) detection. The electrokinetic potential measurement results show a potential increase forpleas the arsenopyrite treated with ZnSO4 in the pH range 7.5–9.0, which could be attributed to the formation of the precipitated zinc carbonate (ZnCO3(S)). For arsenopyrite treated with both ZnSO4 and SIBX, the electric surface potentials also display an increase, to approximate the values with solely ZnSO4 treated, at pH 7.5–9.0, indicating the inhibition of ZnCO3(S) upon the SIBX adsorption onto arsenopyrite. Adsorption results demonstrated that SIBX adsorption onto arsenopyrite indeed was inhibited at the pH 7.5-9.0 through the sharp decrease in SIBX adsorbed amount with ZnSO4 as the depressant at this pH range. SEM observation and EDS detection results verify the formation of colloidal ZnCO3 on the arsenopyrite, with ZnSO4 as the depressant in combination with Na2CO3.

Keywords

• colloidal zinc carbonate
• depressant
• flotation
• adsorption
• arsenopyrite