The effect of saline water on mineral flotation – A critical review

• Mineral flotation plants using saline water are outlined.
• Saline water enhances the flotation of coal and other valuable minerals.
• Three mechanisms explain the improved coal flotation in saline water.
• Studies on sulphide flotation and recovery of gangue in saline water are limited.
• The properties of flotation reagents in saline water have not been studied.

Due to scarcity of fresh water and stringent regulations on the quality of discharged water, more and more flotation plants have to use groundwater, sea water or recycle water with a high concentration of electrolytes. Although a number of studies have been conducted to investigate the effect of saline water (or salt solutions) on mineral flotation, effective ways to solve the problems encountered in mineral flotation plants using saline water are currently not available. This paper presents a review of published articles addressing the effect of saline water on the interfacial phenomena taking place in the flotation process, such as surface wettability, bubble-particle collision and attachment, mineral particle interactions and frothing. This review provides an overall picture of the current status of studies in this area and pinpoints directions of future research to address different problems associated with using saline water in mineral flotation.