Reward Minerals (ASX: RWD) has achieved an encouraging potassium recovery of 91.9% in a harvest grading 6.97% potassium after adding a fourth evaporation stage to its recent pilot evaporation trial of samples from its Lake Disappointment Potash Resource in Western Australia.
Recoveries of 80.2% in a harvest grading 8.06% potassium were achieved prior to addition of the fourth stage.
Importantly, the sodium chloride content of the harvest products were low at 9.95% and 11.5% NaCl respectively due to the back mixing of high magnesium chloride brine remaining from the late stages of the brine evaporation cycle.
A previous 10,000 litre pilot evaporation trial carried out by Reward at Sylvania Station earlier this year had resulted in NaCl content of between 29.8% and 63.5%.
The results demonstrate that this technique should prove very effective in processing Lake Disappointment brines for Potash recovery.
Reward noted that maintaining the NaCl content below 20% has the potential to eliminate the flotation stage from the currently proposed flowsheet as the NaCl will dissolve entirely during the milling/conversion stage.
This would result in a significant reduction in the capital and operating costs for the project.
Further testwork is in progress to optimise the brine evaporation parameters with the inclusion of the end brine and conversion brine recycle streams.
Reward has also engaged Simulus Engineers to revamp the flowsheet/Mass Balance/Plant Design calculations and commence the Lake Disappointment Project Scoping Study.
Lake Disappointment hosts an Indicated Resource of 24.4 million tonnes of potassium sulphate.
The chemistry is similar to the Great Salt Lake in that it is a high sulphate brine.
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