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MEI Online: Environmental Issues: Latest News: February 11th 2011


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::Saline Water Brims with Sustainable Savings

CSIRO research is finding currency in the green economy by capturing the potential of saline water for use in mining and mineral processing.

CSIRO project leader Dr Hal Aral says the industry is facing more “desperate times” through a combination of expanding hydrometallurgical operations, declining ore grades, escalating production pressures and water scarcity.

This is reflected in the “desperate measures” operators are using to secure their water requirements, specifically the use of saline water. This is the case both domestically and internationally.

“Highly saline underground waters are often the only water available to miners in inland Australia," Dr Aral says. “And in northern Chile, seawater is pumped tens of kilometres to mine sites at higher altitudes."

Dr Aral says in Australia the mining industry’s use of water increased about 29 per cent between 2000–01 and 2004–05, when it reached two per cent of the total national water consumption.

But mining is competing with other water users such as agriculture for the scarce resource, and is also facing other challenges such as climatic conditions and regulatory requirements.

Using saline water is seen as a practical response that will also improve the sustainability of mineral processing generally, and CSIRO ’s Minerals Down Under Flagship has been investigating this area since 2008.

CSIRO is examining the use of saline water in physical processes, such as crushing, grinding, flotation, magnetic and gravity separation, and as a diluting agent in lixiviant preparation. The research concentrates on using seawater and saline underground water without any pretreatment, and recycling available water as much as possible.

While saline water can cause corrosion to pumps, pipes and other components at mine and mill sites, Dr Aral says the advantages outweigh the disadvantages where fresh water is unavailable.

“Use of seawater, with little or no desalination, could enhance the economic feasibility of mining operations."

In one case study, process flowsheets have indicated that a South Australian copper concentrate-producing company could reduce its reliance on bore water by recycling saline water from processing.

The research estimated the company could reduce its bore water consumption by about 260 tonnes per hour, also effectively reducing power costs and associated greenhouse gas emissions.

Dr Aral says this translates into a saving of about $250,000 a year based on pumping 260 tonnes per hour from the borefield to the plant at a cost of 10 cents per kilowatt hour. The only modifications required would be some additional pumps.

Potential savings would significantly stack up over the life of the mine.




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