Effect of seawater on flotation separation of sphalerite from pyrite

There is divalent magnesium and calcium ions existed in seawater. Under alkaline conditions, magnesium and calcium ions would react with hydroxide ions to generate insoluble hydroxyl complexes or hydroxide precipitates. In flotation process, the hydrophilic substances and collectors compete for adsorption on the surface of minerals, thereby reducing the floatability of minerals. In this study, the effects of seawater on the flotation separation of sphalerite from pyrite were investigated. The results show that under strong alkaline conditions, seawater has significant adverse effects on the flotation separation. Flotation regulators such as ethylenediamine tetraacetic acid, sodium hexametaphosphate, and sodium silicate can eliminate the adverse effect to a certain extent. The mechanisms were revealed through micro-flotation experiments, contact angle measurements, zeta potential measurements, XPS analysis and FT-IR analysis.