Abstract: A process for recovering lithium phosphate and lithium sulfate from a lithium-bearing silicate is described. The process includes adding from 800 kg/t to 1600 kg/t of sulfuric acid to a slurry of the lithium-bearing silicate and from 40 kg/t to 600 kg/t of a source of fluoride to produce a leach mixture and heating said leach mixture. A lithium-bearing solution is then separated from the leach mixture and its pH is increased sequentially to pH 3.5 to 4, pH 5.5 to 6 then pH 10.5 to 11 to precipitate, respectively, a first, second and third set of impurities therefrom. The first, second and third sets of impurities are separated from the lithium-bearing solution and lime is added to maintain a soluble Ca concentration of at least 30 mg/L. The lithium-bearing solution is then softened by adding a two sequential amounts of phosphate to precipitate fluorapatite and apatite, respectively. A third amount of phosphate is added to produce a lithium phosphate precipitate which is then separated.

Abstract: A process for recovering lithium phosphate and lithium sulfate from a lithium-bearing solution, such as a brine or pregnant process liquor is described. The process includes adding phosphate to the lithium-bearing solution to precipitate lithium phosphate and then separating the resulting lithium phosphate precipitate from the solution. The separated lithium phosphate precipitate is then digested in sulphuric acid to produce a digestion mixture from which a lithium sulfate precipitate is separated. An alkali metal hydroxide is added to the separated solution to produce an alkali metal phosphate solution and this is recycled for use as phosphate in the first step of the process.

Abstract: The disclosure relates to processes for extracting lithium from an uncalcined lithium-bearing silicate and recovering a lithium salt therefrom. A slurry of the uncalcined lithium-bearing silicate and a caustic solution is heated in an autoclave to provide a Li-rich sodalite phase. The Li-rich sodalite phase is leached with a dilute acid to produce a lithium-rich pregnant liquor. Various subsequent processes to treat the lithium-rich pregnant liquor to recover a lithium salt, such as lithium phosphate, lithium carbonate, lithium sulphate or lithium hydroxide, are described.

Abstract: A process for recovering lithium from lithium-bearing materials, in particular lithium bearing silicates such as spodumene, is provided. The process involves the steps of mixing the lithium-bearing material with a source of fluoride, such as calcium fluoride or hydrogen fluoride, in the presence of sulphuric acid at 90° C. for ?3 h to extract ?80% Li. Lithium values may be recovered as >98% purity lithium carbonate by raising the pH of the pregnant liquor solution (PLS) to pH<4 to precipitate Al and fluoride from solution, with a subsequent softening step to bulk remove excess calcium sulphate, followed by evaporation and precipitation of lithium carbonate.