Enhancing the efficiency of hydromineral raw material processing through preliminary precipitation of macrocomponents from brines

Hydromineral resources, such as the underground brines from oil and gas fields, are a promising source for the extraction of strategic metals, particularly lithium, as well as other valuable products like magnesium and calcium salts. To improve the efficiency of selective extraction of valuable components from hydromineral raw materials, this study investigates the potential for reducing the concentration of macrocomponents during the initial stages of the processing workflow. Chemical analysis of brines from various oil and gas fields in the Irkutsk region revealed their high mineralization, driven by the presence of calcium, magnesium, potassium, and sodium chlorides, alongside significant concentrations of microcomponents such as lithium (Li) and strontium (Sr). The phase composition of the raw underground brines, primarily consisting of tachyhydrite and sinjarite, was examined, along with post-precipitation product samples, which contained substantial amounts of strontium chloride hydrate. The study demonstrates the feasibility of separating brine components by transferring the majority of calcium, potassium, and iron into the precipitate. The parameters influencing the precipitation process and their effect on the quality of the resulting products were established. Subsequent sorption extraction of lithium and ion-exchange purification of the primary lithium concentrate enabled the production of a lithium-containing product with minimal impurities, achieving over 86 % lithium recovery. As a result, the concentration of major macrocomponents in the primary lithium concentrate was significantly reduced compared to the original brine: calcium to 0.18 % by weight, potassium to 15 % by weight, magnesium to 0.19 % by weight, and iron (II) to less than 0.02 % by weight.