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Media Release

12 September 2006

Greener solutions for acid generating mine waste

Current technologies used to treat acid generating mine wastes have been shown to be effective in the short term but acid reaction and treatment mechanisms are not fully understood, limiting the effectiveness of assessment and long-term control.

Researchers at UniSA’s Applied Centre for Structural and Synchrotron Studies (ACeSSS) have been awarded an Australian Research Council Linkage grant with industry partner AMIRA International Ltd worth almost $1 million over four years to critically evaluate reaction mechanisms and products in mining waste treatments.

In Australia alone, the cost of managing wastes from operating mines exceeds $80 million annually, with more than $600 million in inherited liability at abandoned sites, according to ACeSSS chief investigator Professor Roger Smart.

“If the outcomes of this research can make a few per cent difference to these huge mining costs, then savings of many millions of dollars for industry can be achieved,” Prof Smart said.

The research is being undertaken by ACeSSS chief investigators Prof Smart and Dr Jun Li, with industry partners, AMIRA (company sponsors Rio Tinto, Zinifex, PT Freeport Indonesia, Teck Cominco Canada), Environmental Geochemistry International Pty Ltd (site consultants), Levay & Co Environmental Services, and Boojum Research in Canada.

Having a fundamental understanding of reactions in acid rock drainage treatments will enable us to more accurately predict when acid will be produced, improve waste management over the long-term, and reduce uncertainties, according to Prof Smart.
ACeSSS will undertake five main programs of fundamental and applied research with its industry partners and sponsors.

“Program one is about improving our understanding of reactions with limestone, the main additive used to treat sulphide wastes,” Prof Smart said.

“The secondary minerals formed by waste treatment processes are being examined in program two. We are developing methods to identify these minerals and to determine if they store acidity.

“Program three looks at minerals within wastes that neutralise but are not assessed in processing because they neutralise at a slow rate. These minerals help to control acid mine drainage (AMD) without any additives. They neutralise continually over the life of a waste dump. We are developing methods to assess their neutralisation value,” Prof Smart said.

In program four researchers will work closely with company sponsors, taking samples from their operating sites to study the different developmental stages of reaction mechanisms in the waste and treatments using neutralising products such as limestone, cement kiln dust, fly ash waste and red mud.

“In program five we are collaborating with Margarete Kalin at Boojum Research in Canada, who has been following sequences of reactions on site samples collected over 20 years. Valuable information from these long-term studies will help us to determine which secondary minerals take up toxic metals such as copper and nickel, as well as acid,” Prof Smart said.

Kalin uses sophisticated ecological wetlands to treat AMD runoff by raising the pH and removing toxic metals using natural microbiological processes that continue to clean the waste dump beyond management.

“If we work out how to treat waste early, we can substantially reduce the remediation costs associated with leaving cleanup to the end of mining operations. That is now well recognised by the companies.”

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