The cyclic nature of brine production
Production Cycle
During production the brine contained in the lake playa drains under gravity towards the trench network and is subsequently removed by pumping. This creates a hydraulic gradient toward the trench and brine is drawn some distance through the aquifer toward the extraction point.
Over time the aquifer immediately surrounding the trench is partially dewatered with the drainable brine removed from the sediment, but the retained brine still held in place by surface tension.
Recharge Cycle
Western Australian Salt Lake playas receive some water input from rainfall and run-off annually. Direct rainfall lands on the playa each year, and most years, heavy, cyclonic rain events cause run-off from the surrounding catchment onto the Playa. This water infiltrates the playa surface and re-fills the drainable pores in the aquifer. The larger rainfall events usually occur from January through to March.
Mixing Cycle
The water that has infiltrated and refilled the drainable porosity mixes (by physical diffusion) with the brine held in retained porosity.
Through repeated production cycles the potassium held in retained porosity is gradually extracted
