GROUNDWATER

Australian Potash's Lake Wells SOP project update

Australian Potash Limited’s managing director and CEO, Matt Shackleton has provided an update on the company’s Lake Wells sulphate of potash (SOP) Project (LSOP).

 17 of the planned 79 production bores have successfully been developed into the Lake Wells SOP Project’s borefield by Australian Potash Ltd

17 of the planned 79 production bores have successfully been developed into the Lake Wells SOP Project’s borefield by Australian Potash Ltd

"The LSOP carries Australia's largest JORC compliant measured resource of SOP precisely because it is data rich," said Shackleton. "The current focus of our approach to developing this resource, in addition to continued bore development, is the bore performance verification programme.

"Lake Wells will be a 100 per cent borefield brine extraction project. We will not rely on trenching for brine supply. The pre-production pumping programme will confirm the metrics at each bore, primarily grade and flow rates. These are key measures of our ‘mining' method.

"Flow rates observed in initial testing are consistent with the LSOP's FEED hydrogeological model1. This is a very encouraging start and reflects the level of understanding our team have of the 18.1 million tonne resource.

"We are pleased to report that the bore development programme is now well ahead of the project schedule's critical path. In line with that schedule, the field team will now revert to single shift drilling until March 2022. This allows the allocation of resources to other critical path items, detailed vessel design, additional verification programmes on feed salts composition and so on, to maintain schedule."

The efficiency of a solar salt brine operation is a function of many variables, including primarily grade of contained mineral of interest, and flow rate of abstraction. A critical concentration of potassium is required to make a sulphate of potash product, below which level the costs of abstraction render the operation unviable in most pricing environments.

In a bore pumping operation, upon completion of the construction of each bore it is critical that the bore is pump tested to assess the efficiency, to determine the maximum flow rate from the bore, and provide critical input in the flow model that ultimately determines the long-term pumping rate.

Initial pumping test analysis only provides a maximum rate that the bore can be pumped under prevailing conditions. The long-term maximum pumping rate will be lower due to drawdown interference from other pumped bores and boundary effects due to the size of the aquifer. The maximum flow rates are not used to determine pump sizes for permanent installation, rather the maximum rate provided by an initial test pumping analysis provides an upper limit on the size of the pump.

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