Mining

Mining

mining

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.

Obviously, the type, amounts, and properties of waste produced on mines varies with the resources being mined, the process technologies used, and the geology at the mine site. However, guidelines on waste management and mine closure have been developed at international, national, and regional levels and we like to use them 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, therefore, 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.

We also recommend including in the plan the fact that, when waste rock is clearly uneconomical, even for future mining, it must be prevented from contributing to acid mine drainage.

Other factors to take into consideration are the overburden, slags, water treatment sludge, tailings, and gaseous waste. The overburden, usually piled on site for cost-effectiveness, should ideally be used for recontouring and revegetation when the mine is closed. 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 days of depositing tailings directly into rivers or wetlands, introducing sediment and contaminants and adversely affecting aquatic life, are long gone. But the design, management, rehabilitation and closure of tailings storage facilities and, indeed, the hydraulic remining of tailings still all call for highly specialised skills.

When it comes to gaseous wastes, including dust and SOX, up to 97% can be removed with gravity collectors, cyclones, electrostatic precipitators, and wet or dry scrubbing techniques.

Planning

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, for instance, we were one of the first companies in Africa to achieve EU accreditation as Expert Supervisor for Asbestos Removal [link to Services page, Asbestos removal]. We offer:

  • The ability to start work immediately because of our relationship of trust with the Department of Labour, which enables us to accelerate work plan approvals.
  • Stripping of the raw, unprocessed product
  • Stripping of solid or bound asbestos such as that found in fascia and ceiling boards and panelling.
  • Stripping of boiler cladding
  • Advisory services on the preparation of tenders for the removal of asbestos from premises 
  • Advisory services related to legal compliance.

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

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 three decades, EnviroServ is ideally positioned to help with all mining waste management requirements.

If you would like to find out what options are available 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​.