Effect of seawater on flotation separation of galena from sphalerite

Abstract

Magnesium and calcium ions in seawater react with hydroxide ions to generate insoluble hydroxyl complexes or hydroxide precipitates, which affects the floatability of sulfide minerals and causes uncertain effects on flotation separation. In order to ascertain the mechanism of the effects, the flotation separation of lead and zinc in seawater was investigated in this study. Compared with that in DI water, Pb grade in lead concentrate decreased from 59.30% to 53.00%, and galena recovery decreased from 63.47% to 47.79%. The SI decreased from 2.051 to 1.451. The results show that under strong alkaline conditions, seawater has significant adverse effects on the flotation separation. When EDTA, SHMP and SS were added, the SI altered from 1.451 to 1.435, 2.271 and 2.137, respectively. This demonstrates that regulators can eliminate the adverse effect to a certain extent. The mechanisms were revealed through micro-flotation tests, contact angle measurements, bubble-particle attachment tests, zeta potential measurements, XPS analysis and FT-IR analysis.