Challenges in Flotation of Cu-Mo Sulfide Ores in Sea Water

摘要

Sea water and saline water are usually considered detrimental for the flotation of copper-molybdenum ores. A desalination stage is assumed necessary to improve the quality of water for the use in flotation process. However, the effect of sodium chloride and other electrolytes improve the floatability of natural hydrophobic minerals. Hence, salinity by itself is not a limitation in mineral flotation. However, the chemistry of sea water is much more complex that a simple sodium chloride solution. Chemical factors such as the buffering effect of sea water, which increases lime consumption; and the precipitation of hydrophilic colloidal particles in alkaline media, which may exhibit depressing effect on some minerals, must be taken into account. It was found that when Cu-Mo sulfide ores are floated in sea water, molybdenite (MoS2) is strongly depressed at pH>9.5. Upgrading of copper concentrates takes place by pyrite depression, but when pH is increased up to the values at which molybdenite is depressed, non-conventional pyrite depressants are needed to avoid Mo losses. Therefore, the use of sea water requires innovative solutions to these specific problems. This paper attempts to describe the advances in the Cu-Mo sulfide ore flotation in sea water, and to identify the most important and challenging issues.