Froth flotation in saline water

Abstract

The use of seawater in mining/metallurgical operations seems to be the only sustainable solution in many zones with limited resources of fresh water. This requires new flotation technologies for processes which are to be carried out in highly concentrated electrolyte solutions. This paper reviews fundamental aspects of flotation in aqueous solutions with high concentration of inorganic electrolytes. Salt flotation, the process of flotation of inherently hydrophobic solids in concentrated electrolyte solutions, is especially suitable for theoretical analysis since no other organic agents are used in it. Starting from this example, the case of flotation of sulfide ores (chalcocite, chalcopyrite, pyrite and molybdenite) is discussed. The flotation of Cu-Mo sulfide ores requires the use of flotation agents, which are different for the inherently hydrophobic molybdenite and hydrophilic copper sulfides. The process is commonly carried out in alkaline pH adjusted with lime to depress pyrite, but in seawater depressing effect of Ca ions on molybdenite flotation is augmented, and different pyrite depressants are needed. © 2011 Hosokawa Powder Technology Foundation.