Application and electrochemical depression mechanism of sodium sulfite on the flotation separation of galena-pyrite mixed concentrate in Yiliang typical high-sulfur lead-zinc deposit

The high content of pyrite in high-sulfur lead-zinc sulfide resources affects the electrochemical properties and floatability of galena and sphalerite, which results in difficult flotation separation. In this study, the negative effects of a high-alkaline process were weakened by introducing an efficient mixed depressant CaO + Na2SO3 in selective flotation separation of galena from pyrite. Flotation separation tests of real ore samples showed that the mixed depressant was more efficient than single CaO (5000 g/t), and the best process conditions of Pb grade 64.01 % and Pb recovery 88.45 % were obtained. The effects of Na2SO3 on the electrochemical interaction between the two minerals were studied by micro-flotation tests, electrochemical, ion dissolution, UV-Vis measurements, zeta potential measurements, and X-ray photoelectron spectroscopy (XPS) detections. Results indicated that Na2SO3 could weaken the galvanic interaction between galena-pyrite and reduce the Pb2+ dissolution from the galena surface. Na2SO3 could desorb the collector ethyl xanthate pre-adsorbed on the pyrite surface.