Cyclic solution mining of borate ores

摘要

A method of recovering boric acid from a subterranean deposit of colemanite ore by solution mining, comprises: supplying a leach solution comprising hydrochloric acid to the subterranean deposit via an injection well in communication therewith, whereby colemanite ore is dissolved and an aqueous pregnant solution of boric acid and calcium chloride is formed in the deposit; withdrawing the pregnant solution of boric acid and calcium chloride from said deposit via a production well in communication therewith; separating boric acid from the withdrawn solution; adding sulfuric acid to the resultant concentrated solution from which boric acid has been separated, whereby hydrochloric acid is regenerated therein and CaSO4.2H2O is formed; separating CaSO4.2H2O from the resultant solution containing regenerated hydrochloric acid thereby forming a regenerated leach solution; and recycling the regenerated leach solution to the subterranean deposit of colemanite via an injection well.