During production, mines play a significant role in boosting the economy and contributing to the wellbeing and vibrancy of local towns and communities. When production ends, closure and remediation becomes a critical stage in the lifecycle of mines, as it determines the long term impact of this land and the affected stakeholders.
“How mining operators approach the end of production has wide-reaching social, economic and environmental implications, making it an important ESG consideration for all mining companies,” says Paul Howard, Managing Partner for Gerard Daniels. “Despite the importance of mine closure and remediation, cost can be prohibitive for some mining companies, particularly in the junior sector or when this process isn’t well planned.”
Unfortunately, the mining industry’s failure to deliver on this critical requirement in the past has left a negative legacy of abandoned mines around the world. There are an estimated 80,000 disused mines in Australia; up to 500,000 in the US; and it is estimated some 10,000 in Canada. In Australia, the CSIRO predicts an additional 240 mines will approach closure by 2040, driving annual spend on closure and rehabilitation in excess of $4b.
The impact of remediating disused mines
When mines are producing, they generate a lot of money and opportunity for local communities, but at the end of their operational life much of the revenue and associated benefits can cease. “Good planning limits the possible negative social and economic impact of mine closure, as the more time there is to design and budget for remediation, the more choice there is in how the land and assets can be used,” says Paul.
The proper closure, decommissioning and remediation of disused mines is also important for mitigating a range of environmental hazards. For example, if exposed tailings dams are left in place, trace metals can contaminate the surrounding air, soil and groundwater; while abandoned coal mines can release residual methane into the atmosphere, long after mining activities finish.
To reduce the environmental and social impact and economic burden of disused and abandoned mines, most major mining regions around the world now require plans for the mine closure and to be built into project design, making it an essential part of approving new mines. Many governments also have environmental bonding systems in place to provide economic assurances for when mine production ends.
“When land restoration/rehabilitation is an afterthought, there’s rarely enough time or money left to do what needs to be done properly. But with the right amount of planning, disused mines have the potential to be used in ways that create new social, economic and environmental opportunities,” says Paul. “And by tying this into the up-front process of obtaining mining licences and leases, there is a financial imperative for mining operators to plan, budget and deliver on this requirement.”
Breathing new life into disused mines
There are many different ways to approach the remediation of disused mines, with the decision often shaped by the budget; timeframe; the commodity was previously mined; and the availability of expertise.
Traditional remediation
Reforestation is a traditional remediation approach that limits the environmental impact of mining operations and brings biodiversity back into mining areas. Simultaneously mining for deposits while conducting the reforesting is an effective way to achieve this. This approach is well suited to mineral sands or bauxite operations and other shallow mineral deposits that extend over long distances.
“There are some reforested areas in Western Australia’s Darling Ranges where this approach has been used so effectively that the vegetation is now almost as mature as when mining first began,” says Paul. “Restoring this land progressively gave it time to recover while mining continued in the area, but this was only possible because it was planned for early and incorporated into the ongoing operation of the mine.”
Other traditional remediation approaches include storing rainwater to address water security; creating green communal spaces like parks and playing fields; and building new community facilities – as Alcoa did with the provision of land for the location of Perth Motorplex. “With the right approach, disused mines (and surrounding buffer zones) can become really valuable and fertile land that supports the community in many different ways,” says Paul.
Reviving old mines
As technology advances, so too do the possibilities for reviving old mines. “When mines are in operation, materials that don’t make the cut-off grade are stored in tailings dams. But as new technologies emerge a much lower grade of materials can be extracted, turning previously closed mines into newly reactivated mining operations,” says Paul. “There is also growing interest in using these technologies to extract the critical minerals often associated with older abandoned mines, that it was not previously economic to recover.”
Green and sustainable energy
Green innovation is rife in the mining industry, with endless opportunities to apply new and emerging technologies to remediate disused mines.
Pumped-hydro systems use the movement of water to generate energy. Often implemented at disused open cut mines, this technology works by moving water from a lower reservoir to a higher one. When energy prices and demand are high it is then released, turning turbines and generating energy as it flows back down. For example, the K2-Hydro project uses pumped-hydro at the former Kidston gold mine in northern Queensland, producing enough energy to power 143,000 homes for at least six hours.
- 2024 has seen a surge in the development of potential gravity energy storage systems for the mining industry. This technology involves capturing, storing and releasing the gravitational energy that’s created when weights (such as sand or concrete blocks) are raised and lowered in the shafts of deep underground mines.
- Geothermal energy can be harnessed from deep underground mines when they are flooded. To achieve this, existing dewatering pumping systems are repurposed to move water up to the surface, where a geothermal heat recovery process captures this naturally occurring source of energy.
- Compressed air storage is another example of putting end-of-life mines to good use. It involves pumping high-pressure air into the cavities of disused underground mines, then releasing it and using the pressure to turn turbines and generate energy.
Having the right team and talent in place to embrace these opportunities in the early design phases will be critical for future successful mines. Boards and Executive teams need to be driving this long-term thinking as part of their ESG strategy.
“There will always be barriers to overcome in the remediation of mines, but the industry is starting to think differently, and innovation is fueling this shift,” says Paul. “Mining operators now recognise that with the right approach, mines at the end of their operational life can become valuable assets that give back to the community, restore the environment and can continue contributing to the local economy, enhancing rather than detracting from the social licence to operate for mine operators.”
Remediation is integral to the sustainable and responsible design and operation of mines. For help developing your talent strategy or the capacity of your leadership to deliver on this, connect with Paul or reach out to your local Gerard Daniels team.
