Mine Pit Lakes

Mine Closure and Mine Pit Lakes

Recent estimates suggest that almost 90% of Australia’s ~95,000 mines are inactive, but just under 4% of these inactive mines are classified as rehabilitated. These figures reflect global trends, where abandoned or former mine sites are common. Shifting the focus from rehabilitation after mining ceases, to alternative post-mining reuse will create new opportunities, and in turn, could yield future potential benefits for mining regions. However, there are numerous regulatory, technical, and economic hurdles to the likelihood of reuse success.

In particular, significant opportunities and challenges arise from mine pit lakes. These form when water entering the mine pit from groundwater or surface flows, ceases to be pumped out at the end of the mining activity. On one hand, there is potential for pit lakes to provide a valuable water resource for nearby communities; on the other hand they can create environmental and safety hazards. Understanding post-closure risks and the potential value of post-closure pits and pit lakes will support mine relinquishment and sustainable post-mining environments and livelihoods.

ChemCentre’s research is helping to address the environmental legacy of mining in WA and support better planning of, and a reduced environmental footprint for, future WA mines. The data generated will assist government and industry in better defining the residual risks of existing pit lakes and identify opportunities for beneficial post-closure uses.

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Research Projects

CRC TiME Project 4.9: Mine Pit Lake Assessment and Management: A national initiative to support mine closure and regional opportunities (2023-2027)

Pit lakes could provide a valuable water resource for regional communities; on the other hand they can create environmental and safety hazards. Understanding post-closure risks and the potential value of post-closure pits and pit lakes will support mine relinquishment and sustainable post-mining environments and livelihoods. ChemCentre is a major research participant in the Cooperative Research Centre Transformations in Mining Economies (CRC -TiME) which aims to drive transformational change and enable regions and communities to transition to a prosperous and sustainable post-mine future.

This project will:

  • Provide national guidance to support decisions on new mines and closure plans, including development of a nation-wide pit lake classification framework and guidance on the level of assessment required for different mine risk profiles.
  • Produce stakeholder ‘common language’ tools around opportunities and risks associated with pit lakes.
  • Undertake closure/relinquishment case and field studies to define the residual risks of existing left-in-place pit lakes, the opportunities for beneficial uses post-closure, and how stakeholder aspirations can be matched with what is technically possible.

 

Project Partners

ChemCentre, CSIRO, Curtin University, Flinders University, University of Queensland, University of Western Australia, BHP, Rio Tinto, MRIWA, Energy Australia, GHD, Iluka, South32,  WA Department of Water and Regulation, Ecological Services Australia, Aurecon, FMG, SA Department of Energy and Mining, WA Department of Mines, Industry Regulation and Safety, Greater Whitsunday Alliance, Isaac Regional Council, Central Highlands Development Commission, Office of the Queensland Mine Rehabilitation Commissioner, Premier Coal Limited, WA EPA, NT EPA.

More information

For more information on this project please visit CRC TiME.

CRC TiME Project 3.3 Hydrological and geochemical processes and closure options for below water table open pit mines (2021)

This project examined the potential opportunities, and value of other beneficial water uses, for mine pit lakes, conducted by a team with expertise in groundwater and surface water flow, water chemistry and water quality and an understanding of mine operational requirements. It summarised current challenges and opportunities and the key research needed to enable water management to achieve environmental, cultural and economic goals.

Project Partners

ChemCentre, BHP Group Operations Pty Ltd, Rio Tinto Services Limited, Newmont Mining Services, Fortescue Metals Group Ltd, Department of Water and Environmental Regulation, Golder Associates Pty Ltd, South 2 Group Operations Pty Ltd, Flinders University, The University of Queensland, University of Western Australia.

More information

For more information on this project please visit CRC TiME.

Project Report

Please click here to view the final report.

MRIWA/ CRC Care project Mine Pit Lakes – Their Characterisation and Assessment for In-Situ Metal Recovery Opportunities and Cost-effective Environmental Management (2018-2021)

In this collaborative project between ChemCentre and CSIRO, real-world field data was generated from representative Western Australian mine pit lakes and pit voids to better inform management and closure plans. Data from mine pit lakes was also used as input data to predict potential for in-situ metal recovery (ISR) opportunities and support the development of methods to determine the feasibility of the recovery of metal values from ore bodies by ISR.

The mine pit lake study generated data to address knowledge gaps in current understanding of the geochemical dynamics of mine pit lakes, particularly in environments with high net evaporation, as commonly occur in the Pilbara, Kimberley and Goldfields. In particular, the data highlighted the importance of comprehensive assessment of groundwater and surface water coupling at individual sites to better understand and predict water quality evolution in a future pit lake.  A screening water quality risk assessment undertaken to examine post-mining uses of mine pit lake water highlighted opportunities to develop case studies for reuse of freshwater pit lakes, and to better understand the potential risk of using saline waters for activities such as aquaculture and livestock production.

The results from the in-situ recovery study provide the proof of concept for an approach to identifying potential for value recovery in mine pit lakes. Investigation of generic and tailored leach tests further confirmed promising potential for the recovery of elements such as Au, Ti and V from some sites, post open-cut mining.

Project Partners

ChemCentre, CSIRO, Department of Water and Environmental Regulation, Department of Mining, Industry Regulation and Safety, Minerals Research Institute of Western Australia, CRC CARE.

More Information

For more information on this project please visit MRIWA.

Project Report

Please click here to view the final report.

Refereed Conference Papers

Linge, K.L., Black, S., Allen, D.A. (2022). Mine Pit Voids Turning into Pit Lakes: Investigating the Effect of Water Quality on the Leaching Potential of Representative Pit Rock Lithologies. 12th International Conference on Acid Rock Drainage (ICARD) Virtual, Australia, 18-24th September.

Linge, K.L., Black, S., Allen, D.A., (2020). Mine Pit Lakes: Characterisation of Water Quality and Geochemistry to Inform Mine Closure. In Tenth Australian Workshop on Acid and Metalliferous Drainage, 22-25 June. Eds. Edraki, M and Jones D pp. 172-182, The University of Queensland, Brisbane. Available here.

Postal address

ChemCentre
PO Box 1250
BENTLEY DC WA 6983

t: (08) 9422 9800
f: (08) 9422 9801
e: enquiries@chemcentre.wa.gov.au

ABN : 40 991 885 705

Street address

ChemCentre
Whadjuk Noongar Boodjar
Resources and Chemistry Precinct
Corner Manning Road and Townsing Drive
Bentley WA 6102

Reception: Level 2, South Wing, Building 500.

Deliveries: Ground floor - use Conlon Street entrance

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