A new minerals processing report from the Australian Coal Industry’s Research Program (ACARP) has been released.
The project was intended to examine the impact of flocculant addition on tailings deposition density, water retention and the tendency for tailings to form surface crusts suitable for subsequent rehabilitation.
It was prompted from work done by Stewart, Baker and Busch in the 1980s that suggested improvements could be made in de-watering and density by the addition of flocculant.
“The main findings in this report were that we were able to re-flocculate the tailings as it disposed into a tailings dam and it was able to de-water much faster, enabling the water to return back to the plant to be re-used, so to keep the sustainability of the plant going,” SNF Australia’s Daniel Bembrick said.
“Because we de-water it very quickly, we were able to rehabilitate it much faster,” he said.
The technology was not used when first brought to light because in the early 1980s environmental guidelines were less strict and water was in surplus, meaning it was not cost effective.
With the opposite being true today, companies have been forced to look for alternative solutions for their tailings.
“What we’ve started to see in the last 10-15 years is that people are starting to steer away from tailing storage facilities because of their lack of safety, lack of rehabilitation and just not enough water for them,” Bembrick said.
With this flocculant technology studied in the ACARP report companies now have another choice in how they deal with their tailings.
In addition to an increase in water availability, an added benefit of the technology is the potential for greater void space.
By increasing tailing density by up to nearly 100%, a mine site is able to effectively double their void space capacity.
This means that a company will not have to dig new holes or find new void space, but instead use the flocculant technology to increase the capacity of their existing void space.
Environmental benefits are also evident from the report, saving large amounts of water from being wasted. “Pressure from the public has put pressure on the government to stop building wet tailing areas because they’re just environmentally not a very good practice,” Bembrick said.
“With Australia being the driest continent on earth and de-sal plants being built everywhere, in every state, they’re not going to let mine sites throw water out in a dam and just let it evaporate.”