Globally, the mining industry plays a leading role in waste management and is one of the few industries that recycles most of its own waste.
Guidelines on waste management and mine closure have been developed at international, national, and regional levels and EnviroServ uses these as an advisory framework for best practices in mine waste management.
In our view, the main objectives in mine waste management are to manage the very large volumes of waste produced, whether or not they are benign, and to prevent the release of contaminants into the environment. As a base line, waste management plans should look at waste storage area selection and design, strategies for addressing problematic waste, and long-term stabilisation of waste as part of mine closure.
One of the challenges of putting together a suitable waste management place is centred on the fact that the soil and rock removed to provide access to the desired ore and the water, solids, and gases arising from the mining process are all deemed to be waste. However, the difference in mineral content between the ore and the rock from which it was removed can change, depending on market conditions and available extraction technology. In such a case, the waste rock can become a commodity.
We prefer to develop a waste management plan that takes such considerations into account to allow the mine operator as many options for recovery and recycling as possible, thereby extending his potential for profit.
Other factors to take into consideration are the overburden, slags, water treatment sludge, tailings, and gaseous waste. Rather than being discarded, slags can be profitably repurposed as aggregate in concrete and road construction where suitable.
When water treatment sludge contains arsenic or cadmium, it is hazardous and must be disposed of by specialists such as EnviroServ.
The design, management, rehabilitation and closure of tailings storage facilities and, indeed, the hydraulic remining of tailings call for highly specialised skills.
In terms of implementing a waste management plan incorporating all these and other issues, our broad approach is to contain and collect wastes at the point of production, treat the wastes to make them environmentally safe, if necessary, and dispose of them to land, water, or air. For a specific mine, this general approach will be adjusted for cost, environmental performance, and risk of failure.
For specific processes, we have relevant qualifications and are able to provide not only guidance and advice but management services and products. For asbestos stripping, we were one of the first companies in Africa to achieve EU accreditation as Expert Supervisor for Asbestos Removal.
Storage and reclamation
Despite the recycling and reuse of many wastes at mine sites, the majority of waste produced is still placed into storage facilities. The reclamation and long term management of such facilities has become an important part of modern mine development and mine closure and are usually subject to the submission of a plan before approval for mining is given. Regulators may require waste storage facilities to remain stable for a minimum of 200 years, which means they must withstand extreme events such as floods and earthquakes.
Mine closure activities often involve containing and covering tailings to prevent their escape into the environment, minimising the amount of water seeping into surface or groundwater, covering waste rock piles and exposed materials with topsoil and planting vegetation to prevent erosion, and designing the final land formation to minimise erosion and post-closure maintenance. Having served most of Africa’s top mining groups for more than four decades, EnviroServ is ideally positioned to help with all mining waste management requirements.
If you would like to find out about options for your organisation, please contact our Customer Care Line on 0800 192 783 for South African enquiries and click here for the contact details for enquiries across Sub-Saharan Africa.
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