The Patience Lake mine is located within the Patience Lake Member of the Prairie Evaporite Formation.

The 100 m to 200 m thick Prairie Evaporite Formation is overlain by approximately 500 m of Devonian carbonates, followed by 100 m of Cretaceous sandstone, and 400 m of Cretaceous shales and Pleistocene glacial tills to surface; it is underlain by Devonian carbonates (Fuzesy, 1982). The Phanerozoic stratigraphy of Saskatchewan is remarkable in that units are flat-lying and relatively undisturbed over very large areas.

Potash mineralization in this region of Saskatchewan is predominantly sylvinite, which is comprised mainly of the minerals sylvite (KCl) and halite or rock salt (NaCl), with trace carnallite (KMgCl3 · 6H2O) and minor water insolubles.

The Patience Lake mine was successfully converted from a conventional mine to a solution mine after being lost to flooding in 1989.
[https://minedocs.com/20/Allan_Technical_Report_02202019.pdf P.48]

Patience Lake is a solution mine. Solution mining involves the injection of heated brine (a salt and water solution) to extract potash from the underground ore bodies. The resulting potash-rich brine is pumped to surface ponds or crystalizers where the potash is extracted.

Injection Wells
Brine is injected underground and is circulated throughout the mine workings to dissolve the potash and salt.

Submersible Pumps
The brine is pumped to an evaporation pond using submersible pumps.

Evaporation Ponds
As the liquid cools, the potash and salt crystals settle to the bottom of the pond.

Extraction
The cool brine is then heated and reinjected into the mine to start dissolving potash again. The remaining potash in the ponds is removed by floating dredges and pumped to the mill.