Sandfire’s Environmental team conducted field sampling and contributed data to the recently released Mine Pit Lake Study, the largest ever study conducted on mine pit lake water quality in Western Australia. The research was led by a team at Western Australia’s ChemCentre and delivered new insights into the geochemical evolution and environmental impact of mine pit lakes across the State.
The results of the study indicate the main influence on pit lake water quality is the surrounding groundwater quality, particularly in regard to major ions pH, and salinity. Kinetic column leaching tests conducted during the study indicate that metal release from permanently inundated pit walls is low, except when wall material is potentially acid forming, and contains reactive sulphide minerals.
The study also considers the potential for in-situ metal recovery (ISR) and makes recommendations on future studies to evaluate the economics of ISR from pit floors, walls and surrounds.
The outcomes of this study will help to inform Sandfire’s treatment of pit lakes post mine-closure. Sandfire is committed to ensuring we safeguard the environment, and our mines are left in a safe, stable and non-polluting state post closure.
About Mine Pit Lakes
Mine pit lakes commonly form post mine closure when open cut mining has been conducted below the water table.
There are many examples around the world where pit lakes have been used to create a beneficial legacy post mining such as recreation areas (Lake Kepwari at Collie, Western Australia), water supply reservoirs (Wedge Pit Lake at Laverton in Western Australia) and wildlife habitat (Sphinx Pit Lake, Alberta, Canada).
Decisions about the end use of mine pit lakes requires a detailed understanding of the quality and consistency of water chemistry over time.
A copy of the final study report can be found at the Minerals Research Institute of Western Australia website located here.
