METHODS FOR PRODUCING LITHIUM CARBONATE AND SODIUM BORATE FROM CALCIUM-RICH AND MAGNESIUM-RICH BRINE

摘要

The present invention proposes an efficient, advantageous and complex process route for producing sodium borate and lithium carbonate from brine that is exceptionally rich in Ca and Mg, as well as lithium and boron. The aim is to outperform the technical and economical scenarios provided by the currently known technologies and process routes. According to the present invention, the process used for producing lithium carbonate comprises the following steps: (i) filtering brine that is rich in Ca and Mg; (ii) treating the filtrate with hydrochloric acid; (iii) extraction using a solvent (SX); (iv) first purification of the filtrate; (v) second purification of the filtrate; (vi) third purification of the filtrate; (vii) reacting the filtrate with supersaturated sodium carbonate; (viii) thickening and filtering the resulting pulp produced at the end of step (vii); and (ix) washing and drying the lithium carbonate. Furthermore, according to the present invention, the process used for producing sodium borate comprises the following steps: (i) filtering brine that is rich in Ca and Mg; (ii) treating the filtrate with hydrochloric acid; (iii) producing Na2B4O7 by extraction of the acidified brine produced at the end of step (ii) using a solvent (SX); (iv) reducing the quantity of water in the solution produced at the end of step (iii) by solar energy, to obtain a saturated condition; (v) crystallizing the Na2B4O7 produced in step (iii), using an evaporator and vapour to heat the solution and cause evaporation of water in the form of water vapour, as well as to crystallize Na2B4O7; (vi) crystallizing Na2B4O7 by cooling; (vii) recycling the mother liquor to feed the evaporator used in step (v).