Crucial characterisation work on undeveloped bauxite deposits is unlocking opportunities in alumina production for the Australian industry.
Work by the Parker Centre — through CSIRO Minerals — on projects such as the Aurukun deposit in far-north Queensland could help ensure Australia remains the world’s top producer of alumina.
The nation supplies 30% of the world’s demand by refining bauxite ore and demand is rising.
The Parker Centre recently characterised the Aurukun deposit, located close to the commercially important Weipa bauxite deposit at Cape York, for the Queensland Government. The centre’s independent characterisation involves looking at the composition and mineralogy of the ore.
The Aurukun work was done to provide companies tendering to develop the deposit with information on the site. Separate characterisation work was also undertaken for several of the bidding companies.
Queensland Department of Infrastructure’s Dr John Rayner, who helped run the tendering process and commissioned the work, says CSIRO Minerals was chosen to undertake the characterisation work for several reasons.
“It has an excellent reputation within the industry and we wanted to get test work done using contemporary methodology,” Dr Rayner says.
“We needed to have the right to release the results to the tenderers, and it was also important for us to have an organisation which could be seen as totally independent and which would be acceptable to all bidders.”
Project leader Dr Peter Smith says the characterisation work found that the Aurukun deposit was similar to other Cape York deposits, but had a higher amount of reactive silica than those currently being mined.
Although the high level of reactive silica impinges on the economic viability of the deposit, the Chinese company that won the tender, Chalco, has some experience with high-reactive silica deposits, Dr Smith says.
Chalco, which has signed an agreement to develop the deposit, has also called on the Parker Centre for more detailed characterisation work, he says.
Dr Smith says materials characterisation techniques help to determine what the quality of the bauxite is, what problems there may be with developing the deposit and what sort of refinery to build.
Using tools such as x-ray diffraction, a quantitative analysis of the sample is undertaken and its mineralogy is also determined.
As this influences how the elements will behave in a refinery, it helps companies understand what is involved in the development process and whether a deposit is economically viable.
Dr Smith says a detailed characterisation project might also look at the possibility of upgrading the ore by beneficiation, a process to separate unwanted minerals in the ore and thus increase the grade.
Characterisation could also include microscopy-based techniques to look at the mineral associations — which minerals occur together, and how to separate valuable minerals from non-valuable ones.
“For example, some hard-to-get-at alumina may be present in a matrix of iron minerals and you would then need to grind the material to break up the iron to get at the aluminium,” Dr Smith says.
Increasing global demand for aluminium, coupled with the minerals industry boom, has led to increasing interest in bauxite characterisation.
“Ten years ago the search for new bauxite deposits was slow and largely confined to the large multinationals,” he says.
“Now we’re getting more and more of these requests from a variety of clients.”
Dr Smith says it is valuable to have an organisation such as the Parker Centre (through CSIRO Minerals) looking after Australian interests in deciding which mineral deposits to develop.
“We have world-leading expertise in mining and refining bauxite in Australia. It makes sense to have an independent characterisation capacity here.”