Purification of brines by chemical precipitation and ion-exchange processes for obtaining battery-grade lithium compounds

Abstract

Lithium salts are very important in the production of lithium batteries since they are used as precursors for the fabrication of cathode materials that require very low level of impurities (battery grade). Usually, the lithium extraction process from brine first yields lithium carbonate, which is then used as raw material for the production of other lithium compounds. However, it implies an increase in investment costs, considering more equipment and process stages. To remove the impurities and produce battery-grade lithium compounds directly from brines, a laboratory-scale process was developed using the methods of ion exchange and chemical precipitation. Thus, impurity-free brine ready to be used in an industrial membrane electrolysis process is obtained.Different sequences and operating conditions were investigated for the purification of lithium-concentrated brines, removing the main impurities of the natural brines: calcium, magnesium, and sulfate. For the characterization of solutions, crystals, and ion-exchange resins, atomic absorption spectrophotometry, scanning electron microscopy, and X-ray scattering spectroscopy were used. The results indicate that during the chemical precipitation process, lithium-concentrated brine reacted with some additives (precipitating agents) at different stages in the batch reactors. Subsequently, the pulp obtained was sedimented and filtered, eliminating or reducing the impurities of the lithium brine. Thus, the most efficient precipitation sequence was evaluated as a function of the removal percentage of the species. The removal efficiencies obtained for Ca +2 , Mg +2 , and SO 4 −2 were of 98.93%, 99.93%, and 97.14%, respectively.Thereafter, the use of the ion-exchange resins reduced the concentration of Ca +2 and Mg +2 to the values below 1 ppm. The combined use of both processes provided promising results that could be applied in the industry.

Application and Analysis of Bipolar Membrane Electrodialysis for LiOH Production at High Electrolyte Concentrations: Current Scope and Challenges

“…The presence of other elements such as K, Mg, and Ca present in Salar de Atacama brine was not considered, as this study focuses on transport phenomena associated with lithium and the effect of high concentrations. Therefore, a purified brine free of Mg and Ca—as can be obtained by chemical precipitation and ion-exchange processes—was considered for experimental development [ 36 ]. The presence of these elements should be reduced to the minimum possible in order to avoid membrane poisoning [ 37 ].…”

Analysis of a Process for Producing Battery Grade Lithium Hydroxide by Membrane Electrodialysis

“…As anolyte, synthetic LiCl solutions with traces of impurities were used as shown in Table 1 . The chemical composition of the anolyte is based in our previous research [ 34 ], where a concentrated lithium brine was purified in order to obtain magnesium concentration below 0.001 wt%. Anolyte 1 and anolyte 2 simulate a purified lithium brine in different dilution conditions, approximately 14 and 32 wt% LiCl, respectively.…”

Preparation of Battery Grade Li2CO3from Defective Product by the Carbonation‐Decomposition Method

“…As the rapid development of electric vehicles industry, the demands of lithium-ion batteries (LIBs) are increasing drastically because it can provide high energy density, long-run cycle, and excellent storage capacity. [1][2][3][4][5] Lithium carbonate (Li 2 CO 3 ) is often used as an important precursor material for the preparation and/or recycling of cathode materials for LIBs. [6,7] Meanwhile, other applications of Li 2 CO 3 include catalyst for preparation of carbon nanostructures [8][9][10] and the preparation of highperformance glasses.…”