ISR mining has become the industry leading low-cost uranium production method globally – following on from initial use in the 1960s to extensive use at present in Kazakhstan (the world's largest and lowest cost producer of uranium), the United States, China, Russia, and Australia, amongst others. ISR mining is amenable to uranium deposits in certain sedimentary formations and is well known in the industry for comparatively minimal surface impact, high production flexibility, and low operating and capital costs. In 1998, ISR mining represented roughly 13% of global uranium production, increasing rapidly to the point where today it is estimated to account for over 50% of global uranium production. There has been continuous development and improvement of ISR mining techniques in past years, particularly in the two decades since the International Atomic Energy Agency ("IAEA") published the Manual of Acid In-Situ Leach Uranium Mining Technology (IAEA-TECDOC-1239).
ISR mining involves recovery of uranium by pumping a mining solution (also referred to as a "lixiviant") through an appropriately permeable orebody. The method eliminates the need to physically remove ore and waste from the ground – thus eliminating the related surface disturbance and tailings normally related to underground or open pit operations. The mining solution dissolves the uranium as it travels through the ore zone – effectively reversing the natural process that originally deposited the uranium. The mining solution is injected into the ore zone through a series of four-inch cased drill holes called injection wells and pumped back to surface via a similar series of recovery wells. Once on surface, the UBS is sent to a surface processing plant for the chemical separation of the uranium. Following the uranium removal, the mining solution is reconditioned (often referred to as the barren mining solution) and returned back to the well field for further production.