Australian scientists develop technology to make mine waste safer

Australian scientists have developed a small probe designed to locate sulphuric acid in mine waste in order to asses pollution mitigation measures, and which they say is poised to revolutionise the way mining companies monitor the rehabilitation of Australia’s mine sites.

The probe, created by the Commonwealth Scientific and Industrial Research Organisation (CSIRO), monitors oxygen levels in sulphidic mine wastes, which results from the oxidation of sulphide minerals, forming sulphuric acid with water. In order to reduce the contamination of surface and groundwater, mineral wastes are commonly covered with earth or synthetic covers.

“Acid mine drainage caused by the oxidation of sulphidic mining waste is one of the biggest environmental problems faced by the mining industry,” said Dr Brad Patterson, an environmental chemist with CSIRO Land and Water, and who has spent five years developing the probe. “Currently, managing these wastes costs the Australian mining industry around AU$60 million (US$32 million) a year.”

Though there are concerns regarding the long-term effectiveness of earth coverings, it is one of the few cost-effective solutions to prevent mine waste acid from escaping into the environment. The new probe can now accurately and cheaply monitor oxygen levels at various depths under the covers on a continuous basis, giving an accurate assessment of their effectiveness, according to CSIRO. Failings in the earth cover will be immediately discovered, allowing appropriate action to be taken.

“Conventional methods of sampling oxygen concentrations in mine wastes are time consuming and costly,” said Patterson. They are carried out manually and infrequently, possibly only two or three times per year. “The oxygen probes eliminate sampling error, reduce processing time and give a clearer indication of trends in the oxygen concentration,” he said. The probes are particularly useful for monitoring remote sites with the data being retrieved using mobile phones and modems, he added.

The new probe has already undergone testing at a site in Western Australia, and has performed successfully under aggressive conditions such as high acidity, says Patterson.

CSIRO has also developed a probe designed to detect and monitor volatile organic compounds such as benzene and trichlorethene in groundwater and soil.

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