Scientists in Australia have developed a highly effective method for the treatment of mining wastewater which involves the use of the same minerals found in common stomach antacids.
A new technology developed by Australian scientists at CSIRO has been deployed for the first time at a commercial mine in Queensland, where it has proven capable of reducing the sludge content of mining wastewater by as much as 90 per cent for a fraction of the cost of conventional methods.
The technology, which goes by the name of "Virtual Curtain," successfully scoured the heavy metal contaminants from the vast volume of wastewater generated by the mine, converting it into a near pristine product. The result was 20 Olympic swimming pools of discharge possessing a quality almost on par with that of freshly fallen rainwater.
CSIRO scientist Dr Grant Douglas developed the technology after he and his team uncovered a new method for the formation of hydrotalcites - the same minerals found some stomach antacids, which involves fine-tuning the concentrations of contaminants already frequently found in wastewater to the right ratios before raising pH levels.
These hydrotalcites can then be used to gather and trap a broad range of toxic contaminants, including arsenic, cadmium and iron, in one fell swoop.
The use of contaminants which are already found in wastewater to produce the hydrotalcites dispenses with the need for costly equipment or sophisticated chemical processes, thus cutting down on processing costs.
The chief means by which the new process cuts costs, however, lies in its dramatic reduction of the semi-solid sludge which is the inevitable by-product of wastewater processing.
"Our treatment produced only a fraction of the sludge that a conventional lime-based method would have and allowed the mine water to be treated in a more conventionally sound way," said Douglas. "Reducing the amount of sludge is beneficial because the costly and timely steps involved to move and dispose it can be reduced."
The ability of the process to effectively capture metal contaminants also has the potential to generate economic returns via recycling of the concentrated waste.
"The technology can produce a material high in metal value, which can be reprocessed to increase a miner's overall recovery rate and partially offset treatment costs," Douglas said.
The process has already been licensed by Australian company Virtual Curtain Limited, and is commercially available for a broad range of industrial applications.