Hard on the heels of a recently-completed prefeasibility study, Image Resources has reported positive results from beneficiation testwork involving the conversion of ilmenite from its Bidaminna mineral sands project to synthetic rutile. The company believes it could offer an opportunity to enhance the processing, economic, marketing and ore utilisation considerations of its project in Western Australia’s North Perth Basin.
Hard on the heels of a recently-completed prefeasibility study (PFS), Image Resources has reported positive results from beneficiation testwork involving the conversion of ilmenite from its Bidaminna mineral sands project to synthetic rutile (SR).
The company believes the outcome could lead to an opportunity to enhance the processing, economic, marketing and ore utilisation considerations of its project in Western Australia’s North Perth Basin.
Initial metallurgical studies on converting ilmenite to SR used a composited ilmenite sample grading 60 per cent titanium dioxide and a fluidised bed reactor (FBR), with hydrogen as an iron reductant. Management says the testwork yielded a final SR grade of better than 95 per cent titanium dioxide – a notable result considering it is the same level of purity as natural rutile, which is a high-grade feedstock with a typical titanium oxide content in the range of between 92 and 95 per cent.
Minor impurities identified in the SR output included 0.03 per cent chromic oxide, 0.03 per cent calcium oxide, 1.45 per cent silica, 0.10 per cent phosphorous pentoxide, 0.09 per cent vanadium pentoxide, 20 parts per million uranium and less than 50ppm thorium.
Encouragingly, the FBR process was also found to have a lower conversion temperature than the classic Becher SR process that is one of several industrial methods used to produce rutile from ilmenite.
Image Resources managing director and chief executive officer Mr Patrick Mutz said: “The significance to Image of the positive results from this initial SR conversion test cannot be over emphasised as they open the door to the critical value-adding opportunity of potentially upgrading ilmenite from Bidaminna.to SR. Importantly, the potential for multi-decade operating life from these projects could serve to strongly support a justification for capital expenditure for SR production in the event future feasibility study results are determined to be positive. Image is also investigating the opportunity to produce a potentially ‘green’ SR product through the use of ‘green’ hydrogen produced from the hydrolysis of water using the existing solar farm at Boonanarring.”
Following the delivery in June of the Bidaminna PFS, the company is now advancing a definitive feasibility study (DFS) for the project. It includes examining the economic and processing merits of separating its heavy mineral concentrate (HMC) into its component parts and converting ilmenite into synthetic rutile to enhance overall project economics and expand its customer base through the sales of a wider range of products such as SR, zircon, leucoxene, rutile and monazite.
The ilmenite sample used in the conversion testwork was taken from a Bidaminna HMC sample produced by IHC Mining and was considered representative of the project’s deposit. This testwork was a single “sighter” test using initial or preliminary baseline conditions to determine the reactivity of the sample of Bidaminna ilmenite in the bench-scale FBR.
The process involved oxidizing the ilmenite in the FBR, followed by hydrogen reduction and then heated hydrochloric acid-leaching to remove unwanted iron from the cooled ilmenite.
Going by visual observations of the test reactions and final product, management deemed the sighter test as positive, with no obvious material handling issues, no adverse reactions and a final clean SR product. However, the company points out that the test can only be considered preliminary and that additional SR bench-scale testwork is required to optimise its processes.
Ultimately it will include ilmenite and magnetic concentrate feedstocks from the company’s Bidaminna, Yandanooka, and McCalls projects. While additional testwork is required on other samples to develop optimal conditions for the process and cost estimations, impurities in the final SR product are expected to remain at a low level consistent with the Bidaminna ilmenite source.
Preliminary planning is also underway for continuous feed, pilot-scale FBR testing and acid leaching to establish operating parameters for scoping and feasibility studies, to establish risk and scale-up factors and to generate larger quantities of samples of SR product for marketing purposes.
For perspective on the potential value-adding nature of converting ilmenite to SR, Image points to current market prices. Ilmenite is going for up to US$300 (AU$458) per tonne, while market prices for SR are up to US$1250 (AU$1906) per tonne, or about five times higher.
While there is an approximate loss of mass of about 40 to 45 per cent when converting ilmenite to SR, due to the removal of iron and other impurities from the ilmenite, the potential net-value gain per tonne in beneficiation is about 2.5 times the original ilmenite value.
If subsequent metallurgical testwork, bench tests and pilot-scale processing continues to produce similar results to the initial beneficiation study, Image could significantly enhance Bidaminna by maximising ore usage, facilitating the use and blending of ore from multiple sources, extending overall mine life across its projects and selling an enhanced SR product and other derived mineral concentrates.
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