3. Ore processing and production of refined borax and boric acid

Borate ores are mostly mined by open-cast methods (quarries). The few underground mines are at Liaoning in northeast China, Billie and Gerstley in California's Dead Valley, and Emet in Turkey. A case of in situ leaching has also been reported in Barstow (California), where 5% HCl leach solution is injected at a depth of 400 m to extract colemanite .

Treatment processes depend on the size of the deposit, the type of ore and the desired commercial product (concentrate, refined borax, boric acid, etc.).

In most mines, concentrates are produced from borate ores by simple crushing, manual sorting (in salars), screening, settling, washing and classification....