Inert Atmos Technology

Preventing Pollution from Decommissioned Underground Mines

Earth Systems has been a global industry leader in the management of acid and metalliferous drainage/acid rock drainage (AMD/ARD) for more than 20 years. We have developed an innovative technology for rapidly lowering or preventing pollution from decommissioned underground mines. Based on mine void atmosphere control, it provides a cost effective alternative to “water treatment in perpetuity” or accepting ongoing water pollution.

There are more than 400,000 abandoned underground mines worldwide. Many of these discharge acid, metal and salinity contaminated
drainage. The pollution is a result of the exposure of sulfide minerals (such as pyrite) within the mine to atmospheric oxygen. If not managed, pollution can continue for centuries. Solutions for the management of these legacy mines include hydraulic seals which flood the workings and prevent oxygen access to the reactive sulfides, or treatment of the discharge water via costly and ongoing chemical addition. Hydraulic bulkheads are difficult to engineer, can be expensive to install and have some history of catastrophic failure. When water treatment is chosen, it is often considered necessary in perpetuity. For most sites, particularly remote ones, pollution control has simply not been economically viable – until now.

Earth Systems has developed and successfully implemented an innovative, low cost and low risk alternative to existing AMD management options. The rate of pollution generation (ie. sulfide oxidation) from underground mine voids is directly proportional to their internal oxygen concentration. By controlling void oxygen concentrations, pollution can be either lowered or prevented. Earth Systems has developed processes for passively lowering internal oxygen concentrations and minimising the re-supply of air into the mine workings associated with climatic events (ie. mine breathing). Substantial reductions in pollution (50-60%) have been passively achieved to date following strategic engineering work programs that do not interfere with mine water discharge. Complete pollution prevention could be achieved via active inert gas injection, to
overcome air entry due to barometric pumping.

A brief case study showing early results from two derelict mines in Australia is available to download (InertAtmosphereTechnology.pdf). If you have any queries regarding this approach, or potential applications, please call Earth Systems for further information or contact Dr Jeff Taylor on jeff.taylor@earthsystems.com.au