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Mine Rehabilitation:  A New Approach

Mine rehabilitation can be a relativity cheap, short-term activity with expensive long-term financial implication, but more importantly environmentally consequences. The cheapest solution is to start with the end in mind, obtaining the mine closed certificate at minimum life cycle cost.

Looking at the rapid growth of mines within the South Africa, we at PBD-Lime has commenced with the testing and development of limestone (CaCO₃) in mine rehabilitation. We believe that limestone applied in a methodical process can significantly impact on the long term rehabilitation, including but not limited to soil stabilization, pH control, not only in the soil, but also in a preventive manner on rain and seeping water.

Over the last number of years, acid mine drainage and mine rehabilitation has received increasing focus due to the impact on the environment. PBD-Lime is developing a number of products to assist with mine rehabilitation and AMD prevention. These products comprise of the following:

Bedrock: -200mm

Bedrock is a low cost passive lime system that is inserted into the bottom of the pit as part of the first phase of rehabilitation. The product is a mix of course and fine material that allows for protection against flash flooding and ensures long term neutralisation of acid water seeping through a rehabilitated pit. It is a passive layer the forms the last line of defence.

Intermediate: -20mm

Intermediate is used as a layered protection system. Depending on the requirement, the product is applied every couple of meters in layers to ensure that the water can be neutralized as it moves to the bottom of the pit. This is to ensure long term neutralization as well as to minimize the application of more costly agricultural lime.

Block: +50mm Product

Block has been developed for a number of applications. Block can be used as Bedrock, Intermediate material or for the construction of stream linings and also creations of boxed linings for streams, to ensure long-term neutralisation of acid within the stream.

Applying a combination of the products as part of the rehabilitation process will ensure long term neutralization at minimum life cycle cost.

We are entering the testing and monitoring phase early 2012, and will publish the test results and findings as we better understand the models and the factors impacting on the effectiveness. At present we are also considering products that will come available as a result of the published Draft Waste Classification and Management Regulations.  It is anticipated that through blending of these products with limestone, an optimum solution can be created.