An ecological timebomb is ticking away as mining waste breaks down at hundreds of mine sites across Australia. And the potential clean-up bill if local environments are to be saved from the ravages of acidic soil and water could run into tens of millions of dollars. Mines that remove base metals from the environment including lead, zinc, copper, silver, gold, coal and nickel generate mining waste containing sulfides.CSIRO mine site environment research
leader Dr Graham Taylor said when the sulfidic, mining waste was ex posed to oxygen and water it oxidised. causing acid mine drainage. The rusulting contaminants Including arsenic, mercury and cadmium were soluble and would leach into the soil and surrounding water tables, creating severe hazards to the local environment and water ways. Dr Taylor said the biggest Problem

By MICHELLE
POUNTNEY,
environment reporter

was old and abandoned mines, which could cost $100,000 a hectare to rehabilitate. But active mines could spend $10,000 to $35,000 to fix the problem. "It's only in the past 20 years that the potentially catastrophic effects of acid mine drainage have become known to miners. regulators and the public," Dr Taylor said....Dr Taylor said current practice of covering the waste with tonnes of soil and revegetating the area was not effective in the long term. CSIRO researchers have been investigating techniques and strategies to halt potential damage to the environment by stopping oxygen getting to the sulfides. Dr Taylor said researchers were examinlng ways to use a secondary mineral that formed on the waste to seal it.