資源・素材学会 年次大会

Seawater has been reported to exhibit detrimental effect on floatability of molybdenum in a conventional copper-molybdenum (Cu-Mo) flotation circuit owing to the formation of colloidal precipitates, mainly Mg(OH)₂, in seawater at pH higher than 9.5, thus preventing the utilization of seawater in Cu-Mo flotation circuits for mining operation located far from fresh water resources, i.e., in desert areas. On the other hand, kerosene has been known to improve the floatability of molybdenite in flotation processes using fresh water. However, the effect of kerosene on the floatability of molybdenite in flotation process using seawater has not been investigated yet. Therefore, the effect kerosene on the natural floatability of chalcopyrite and molybdenite in seawater was intensively studied in this work. Flotation tests of single mineral of chalcopyrite and molybdenite showed that kerosene could selectively improve the floatability of molybdenite at alkaline conditions. Meanwhile, the floatability of chalcopyrite remained low after the addition of kerosene. Contact angle and atomic force microscopy (AFM) images show that the surface of molybdenite was less covered by the hydrophilic precipitates and the surface relatively more hydrophobic compared to that of chalcopyrite after the addition of kerosene. The flotation tests using mixed mineral of chalcopyrite and molybdenite demonstrated a selective flotation might be possible by employing kerosene emulsion in seawater at alkaline conditions. A mechanism is proposed in this work to understand the phenomenon.