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Media Release

October 4 2006

ARC funding - a big hit for mineral recovery

Flotation is the most extensively used method worldwide to separate minerals from mineral resources. Optimising the recovery of valuable minerals from both fine and coarse particles in flotation is one of the most significant challenges facing the mining industry.

Researchers at UniSA’s Ian Wark Research Institute have been awarded an Australian Research Council (ARC) Linkage grant in collaboration with industry worth almost $4.5 million over four years to develop novel methods to improve mineral recovery from particles of different sizes during flotation.

Losses of valuable minerals from very fine and coarse particles in flotation tailings equate to about $500 million annually in Australia alone, according to joint project leader and director of The Wark™, Laureate Professor John Ralston.

To extract minerals using flotation, water is added to finely crushed ore, producing slurry that is transported to separation tanks where it is vigorously agitated and aerated to create a froth of bubbles. Chemicals are added to stabilise the bubbles and selectively coat the minerals, making them water repellent. This causes the minerals to collide and attach to the bubbles and float to the surface, where they overflow into collection launders, while the residue or tailings sink to the bottom for disposal. The recovered minerals are then filtered to remove most of the water before being dried for transportation.

“Particle size and density, and bubble size and velocity all affect the particle/bubble collision efficiency. In our recent studies we have shown that there is an optimum bubble size that maximises the collision efficiency of ultra fine particles (less than three microns), however, in most operations a wide particle size distribution is present,” Prof Ralston said.

“If the minerals could be recovered efficiently from coarse particles during the flotation process, mining companies could cut costs considerably by saving on the high costs of extensive ore grinding, which is a huge drain on energy resources.

“The funding will enable us to undertake further research to effectively match bubble sizes with a wide range of particle sizes to optimise the collision efficiency and increase mineral recovery,” Prof Ralston said.

Other objectives of the project are to recover minerals selectively during flotation; improve the separation of penalty elements such as arsenic and mercury; optimise grinding and regrinding chemistry and surface cleaning; address composite particle recovery; develop characterisation tools, methods and protocols, and transfer the technology to industry sponsor operations.

“Even small improvements in flotation efficiency of one or two per cent can equate to millions of dollars in savings, depending on the size of the operation and value of the mineral recovered,” Prof Ralston said.

The significance of flotation to the Australian economy cannot be underestimated. Australian Bureau of Statistics figures show that in 2005 more than $75 billion was derived from commodity exports from the minerals and energy industries.

“Australian industry will benefit from exposure to unique methods and information that will enable industry partners to maintain a technological edge using tools developed to optimise operations for improved mineral recovery and increased output,” Prof Ralston said.

Joining Prof Ralston on the IWRI research team are senior research fellow Associate Professor Stephen Grano, who is joint project leader and case study manager; and Associate Professor Daniel Fornasiero, generic study manager, who will play leading roles in interpreting and modelling of flotation data and ore flotation studies for industry partners.

A large number of Australian and international minerals companies have joined together to support this research, facilitated by AMIRA International. Industry partners include Platinum (South Africa), COREM (Canada), CVRD (Brazil), Cytec (USA), Magotteaux (Belgium), Newmont (USA), Outokumpu (Finland), Pasminco (Australia), Phelps Dodge (USA), Rio Tinto (UK) and Teck Cominco (Canada).

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