Improving Water Recovery and Recycling

Mining is a water intensive sector, and improving water efficiency through reduction of water intensity is a key requirement in moving toward a more sustainable mining sector in Canada. To ensure efficiency of processing and extraction and that mining activities do not adversely affect water resources, an integrated approach to water management that takes into consideration water use, treatment and recycling is required. An integrated water management approach can reduce pressure on the environment and reduce costs by reducing the amount of water needed for every tonne of rock produced, and by improving the recovery of valuable metals and other chemical components. Recycling and reuse of process water is an essential step towards reducing or eliminating the intake of fresh water, while at the same time minimizing the release of potentially contaminated process waters to the environment.

The chemistry of the water used to separate the various mineral components can have a significant influence on the overall efficiency of the separation and recovery during the flotation process since water is both a transport mechanism and the medium within which the chemical reactions take place. Relatively limited research and development is available regarding the role of water quality in mineral processing and mineral separation.

When water that is recovered and recycled for use during the mineral separation process, understanding the effects of water chemistry obtained from different water sources on the overall process efficiency becomes important. Membrane separation technologies, in combination with other processes such ion exchange, offer promising ways to not only help minimise water use, but to help control the water quality, remove unwanted contaminants and improve the overall efficiency of the mineral processing and separation circuits.

CanmetMINING, working in close collaboration with mining companies, engineering firms, equipment suppliers, and academia, is looking at options to treat, recycle and reuse process water to improve water use efficiency and to reduce the risk to the aquatic environments from the discharge of mine-water to the receiving environment.