The project will include more than 10 square kilometres of on-playa evaporation ponds, which will promote precipitation of halite while increasing potassium and sulphate concentrations in the brine.
Low permeability clay layer near the surface of Lake Wells provides an excellent barrier to minimise vertical seepage of brine and the company intends to integrate the overlying ‘Kopai’ dunes as pond embankments.
On-playa pre concentration ponds covering 10 square kilometres will take advantage of the surface layer of low permeability clay
READ: Australian Potash’s Lake Wells SOP Project gets confidence boost with adoption of JORC brine guideline
Australian Potash managing director and CEO Matt Shackleton said: “Prior to the construction of full-scale commercial evaporation ponds we need to confirm the most economically and technically optimal construction method for the pond walls – stage I ponds will be approximately 10 square kilometres in area making data gathered in this program vital to future development.
“We know we can take advantage of the surface clay layer to seal the bottom of the ponds - what we are assessing is which is the best wall construction technique to seal the walls of the ponds.
“We call these on-playa trial ponds, as they are built unlined on the lake surface.
Four wall construction techniques will be trialled with external piezometers developed to monitor seepage rates
“This program is one of the final two field programs underway to complete the definitive feasibility study data set – the other is the long-term test pumping program on production wells.
“By the conclusion of the DFS we will have installed and pump-tested approximately 30% of our stage 1 bore-field, allowing APC to move seamlessly into pond fills on development.”
The on-playa trial pond will be constructed in proximity to an existing brine production bore, which will undergo test pumping to add to the aquifer resource model.
Brine discharged from the production bore will be contained within the on-playa trial pond and stand-pipe piezometers will be installed around the on-playa pond to measure pore water pressure in response to pond filling as well as to assess seepage through the barriers.
The trial pond will be constructed by early May and brine discharge will follow with monitoring to continue through June.