Key mine closure lessons still to be learned

摘要

The focus of mining project feasibility studies and operations is still on short-term profitability with little view to a post-closure landscape and liability. The faults of both the original and the operation's mine planners are therefore vested upon the closure teams who must deal with these planning decisions. Following completion of operations, most mining companies that have not adequately prepared for mine closure will face an inability to relinquish their project leases as a result of closure planning process shortfalls. Following from our own closure project experiences and of recent international mine closure conferences, we propose seven key lessons still to be learned if successful mine closure is to be achieved.Firstly, a paucity of baseline environmental monitoring data often incapacitates good closure planning from the outset with a failure to understand key closure risks and risk drivers for the site. Well-characterised environmental information prior to mining disturbance and monitored progressive rehabilitation is a great strategy to address this fault. An insufficient understanding of the physical and chemical characteristics and volumes of waste materials is a second critical fault of closure processes.A third significant issue is contaminated mine waters such as acid and metalliferous drainage (AMD). AMD is arguably one of the single biggest liabilities and management issue post-closure.Failure to engage stakeholders in a documented process is a fourth prime failing often seen with the fifth of mine closure procrastination. Like all of these causes, this problem often arises from thinking mine closure is an activity at end of life-of-mine rather than as a process that begins with the initial mine plan and then regularly continues throughout mine life. Diligent attention to regular planning assessment and stakeholder consultation from an early operational phase may fend off later criticisms, lead to closure outcomes better directed by years of underpinning work and also reduce end of mine costs.A sixth significant closure planning error is the failure to account for the long temporal scales that closure planning must accommodate, particularly so when costing closure. This failure is often due to closure views being short-term, to meet immediate regulatory and operational planning needs rather than focussed on the future.A seventh lesson from historic closure planning is the simple failure to have clear closure objectives and approaches to identified outcomes. This may result in a focus on technical studies that fail to provide better closure understanding, whilst expending hard-won closure-aimed budgets. Driving closure planning by well-defined goals through corporate tools such as closure standards designed to meet both internal requirements and relevant closure guidelines is an ideal solution to avoiding wasted closure resources such as time and finances.Whilst learning and addressing these key closure lessons is no guarantee of successful relinquishment, recognition of these issues and judicious planning to overcome them is more likely to present well-considered closure plans with greater chance of closure relinquishment in a sustainable socio-environmentally manner that maintains a company's and the broader mining industry's licence to operate into the future.