Mineral resources are finite, meaning that the lifespan of any mine is limited. The longevity of operations can also vary considerably. For example, while a copper mine may last for up to 70 years, sources of some resources - such as platinum or iron ore - can have a lifespan lasting as little as a decade (or less).
The eventual closure of any mining operation is hence inevitable, and can potentially have a negative effect on host communities - particularly those that are heavily reliant on mining for jobs and livelihoods - as well as adverse environmental impacts.
Through effective decision-making, however, mining and metals companies can more easily and sustainably transition through the different phases of a mine's lifecycle leading up to its eventual closure. Where mine closure is concerned, ‘mining with principles' means adopting processes and decision-making procedures that support sustainable development throughout the entire lifespan of an operation - from initial planning to design, operation and eventual closure of the site.
The closure in itself is a multi-stage process, taking in:
• Remediation and clean-up;
• Land reclamation, restoration and rehabilitation; and
• Long-term monitoring of the site.
Once a mine's mineral deposits are exhausted, mining companies are responsible for rehabilitating affected land and water courses. This means returning disturbed land to a stable and productive condition, paying particular attention to environmental concerns such as the preservation of biodiversity and the restoration of pre-existing ecosystems. Mining companies are also required to work with local communities to offset any potentially negative social and economic impacts of site closure.
Planning for closure is therefore a core business practice for responsible mining companies, and is ideally considered during the design phase of a new mine. Early stakeholder engagement measures are also essential, as they make closing a mine in a sustainable manner so much easier. Experience shows that closure is as much a managerial and stakeholder engagement issue as it is a technical one, requiring the continual testing of assumptions and recommendations, so as to match evolving conditions and expectations.
For all of these reasons, Principle 2 of ICMM's Sustainable Development Framework commits its member companies to fully integrate sustainable development into their corporate strategies and decision-making processes.
ICMM has also worked with its partners to develop a mine closure toolkit, designed to help companies plan for and effective, efficient and integrated shutdown that minimises risk of any potential damage to either local communities or ecosystems. This toolkit aims to support mine operators in identifying potential problems as early as possible, as well as in minimising the risk of regulatory non-compliance.
ICMM says its members Rio Tinto and Barrick can both provide examples of sustainable mine closure, with Rio Tinto's work in successfully decommissioning and redeveloping the former Sabart aluminium plant in France being a great illustration of how effective planning can produce positive outcomes.
By the 1990s, the relatively small Sabart operation had become uncompetitive, and hence it was closed - with the mine's then-owners abandoning the six-hectare site. In the past few years, Rio Tinto (which inherited the site) has not only collaborated with the local community in planning for the site's future, but also invested millions in a decommissioning and rehabilitation programme - comprising soil decontamination, the removal of 10,000t of contaminated materials (including asbestos), and the demolition of large structures and foundations that were still present on the legacy site.
As of 2017, the decommissioning work was complete, with the land being sold to the local city council at a discounted price and plans in place to transform the site into a new recreational area and business park - boosting the town's economy while creating further employment opportunities.
Following the 2008 closure of its Eskay Creek gold mine in British Columbia, Canada, operator Barrick embarked on a rehabilitation and restoration project to return the environment to a stable condition. This comprised earthwork, re-vegetation and re-contouring of the slopes around the former mine, along with long-term water management plans.
The Eskay Creek mine, like many others, had contained sulphur-based rocks and tailings that, if left exposed, could potentially generate harmful acidic water. The key to preventing this was to starve the rocks of oxygen - so Barrick chose to safely store the waste rock deep underwater, monitoring the site for water quality on a quarterly basis.
This article was originally published by ICMM