How is salt extracted by solution mining?

Solution mining, or brine solution mining, is a method used to extract halite (rock salt) by dissolving underground salt formations to create an artificial brine.1

The process begins by drilling a borehole into a salt formation and lining it with steel pipes. Once the well is prepared, water is injected into the formation to dissolve the salt. Depending on the configuration—such as top injection, bottom injection, or bottom annular injection—the resulting brine is then extracted through the well for processing.1

To control the shape and growth of the underground cavern, operators may inject oil or air, which float on top of the water and inhibit upward expansion. In larger operations, multiple wells may be used to allow caverns to coalesce, with a central injection well surrounded by several production wells.1

Once extracted, the brine is pumped to a plant or solar pond, where the salt is recovered through evaporation. This can be achieved using artificial heat, such as multiple-effect vacuum evaporators or grainers, to produce high-purity evaporated salt.12