The rising uranium price and the increasing demand for nuclear energy due to the exigency to reduce our carbon footprint, have together attracted many investors to reactivate the exploration and mining of uranium in Australia.
Exploration and mining of uranium have been known to contain about 40 per cent of the world’s reserves of uranium.
It has been well-accepted that the efficiency of uranium recovery is influenced by the mineralogical characteristics of the ore. The uranium mineral composition and mode of occurrence affects uranium dissolution, while the bulk composition controls reagent consumption.
Uranium can be commercially produced via conventional hydrometallurgical processes, including acid and alkaline leaching. The processes are efficient; however they can be quite costly for low grade ores.
Combining hydrometallurgical process with radiometric sorting provides a cost-effective means to solving this problem.
Radiometric sorting has been integrated into the flowsheet as an ore enrichment process during the downturn in the uranium industry in the mid-1980s. This technique separates uranium ore from the waste rock, producing a uranium-rich beneficiated ore for subsequent processing in the hydrometallurgical circuit.
While it reduces the load of downstream processing, it also makes the downstream operations more economically viable with reduction in plant capital and operating costs. For example, a decrease in the waste rock content could avoid the long leach retention time. Hence, this technique is particularly attractive when the downstream processing cost is higher than normal.
Vein type deposits show a good potential to be upgraded by radiometric sorting. These deposits contain discrete high grade minerals that are easily separated from the low grade material and gangue.
Radiometric sorting also allows the mining process to be more flexible by providing means to increase the output at the existing facilities and to maintain the output to cope with the declining grades. Modern radiometric sorting technology also allows the unit to be controlled based on the U3O8 upgrade ratio. This is particularly useful when the mineralisation is close to the economic cut-off grade or a rapid response is required to account for the grade changes.
At Mary Kathleen, radiometric sorting recovered about 90 per cent of the uranium in the sorter feed into 40 per cent of the mass. It is expected that radiometric sorting will play an integral role in the minerals industry, particularly in uranium processing.