Abstract

The use of seawater in flotation process is becoming increasingly important; however the complex chemistry and presence of magnesium and calcium hydroxyl-complexes interfere with the recovery of some value minerals as molybdenite. In this work, the impact of seawater with calcium and magnesium removal on floatability of Cu-Mo sulfide ores was analyzed in modified Denver cell. Seawater pretreatment was carried out through 50/50 mixture of Na2CO3 and CaO which promotes Ca and Mg ions precipitation. Then flotation tests were performed at pH 10.6 reached by addition of NaOH. Recovery of Mo in seawater with calcium and magnesium removal was notably increased in comparison to flotation in seawater without any pretreatment at pH 11.5. High pyrite depression was achieved because of the oxidizing atmosphere at pH 10.6 allows the formation of Fe(OH)3. The work has significant implications for the flotation of Cu-Mo ores in seawater without desalination.