Mining employees have a different understanding of the term mine water management; for the rock mechanics engineer it is the de-pressurisation of a slope in an open pit, for the metallurgist it might relate to the water enclosed in the process circuit, and for the tailings engineer it is most likely to pertain to the waste circuit. However with this said, this post uses the term in its broadest context to mean water impacted by the mining project and the impact of water on the mine.
As time moves on and the world becomes more and more environmentally conscious, it is said that water management within a mine or during the entire life span of a mining operation will become increasingly important and a vital matter to consider.
In dry regions water is a scarce and costly resource to the extent that some projects will stall because of a lack of water or because the cost of supply will be excessive. In high rainfall areas, the containment of contaminated water might not be possible without large structures and transfer systems, whose construction and operating costs will also be large. Treatment of water, both as a supply and before release to the environment, has traditionally been expensive.
Water issues should be considered in an integrated way during design, start-up, operation and closure of a mining project. During design, failure to incorporate the various components can considerably undervalue the time and cost of implementation. During start-up, extreme climatic conditions, unplanned during design, can cause flooding of construction works and initial pits or require an additional water supply. Operational matters could include incorrect estimations of plant make-up water, or tailings circuit imbalances or changes to the volume and quality of water as process plants expand or change process technologies. The closure of any mine will include pit lake hydrology and chemistry, runoff from rehabilitated dumps and residual contamination of plant areas, amongst the issues of concern.
The partially flooded open pit in the picture is the result of poor implementation of storm water controls, and will lead to major expense in rehabilitation, as well as significant loss of production, which all could have been avoided.