Utilization of EDTMPA as an eco-friendly depressant for selective flotation separation of cassiterite from calcite in the oleate system

Abstract

In this study, the flotation tests revealed that ethylenediamine tetramethylenephosphonic acid (EDTMPA) as a calcite inhibitor has a stronger depression effect than EDTA (ethylene diamine tetraacetic acid) in the cassiterite flotation process, and the selective depression mechanism of EDTMPA was revealed by zeta potential test, TOC test, XPS analysis and DFT calculation. The flotation test results showed that effective separation of cassiterite and calcite could be achieved at pulp pH of 9.0, NaOL concentration of 1.80 × 10−4 mol/L and EDTMPA concentration of 1.25 × 10−5 mol/L. The selective adsorption of EDTMPA on the calcite surface was ascribed to the strong interactions between the phosphate ions in the former, and the surface Ca2+ ions on the latter’s crystal lattice. DFT calculations also confirmed the strong affinity of EDTMPA for calcite and its weak affinity for cassiterite. The results of this study provide an experimental and theoretical background for the sustainable and eco-friendly separation of cassiterite from calcite.