Regarding the lithium carbonate process

Different raw materials require different methods for extracting lithium carbonate. Mainly lithium ores (lithium mica, spodumene), salt lake brines, and seawater ； The magnesium content in domestic salt lake brines is high, making the separation of magnesium from lithium difficult ； The lithium content in seawater is low, and the extraction processes are not yet perfect. Due to the low total reserves of lithium ore, the production process is complex and energy-intensive. Domestic lithium resources are primarily found in salt lake brines, and there is great potential for extracting lithium from these brines. The following is an introduction to the process of extracting lithium from salt lake brines: 1. The evaporation and precipitation method involves using solar energy to naturally evaporate and concentrate the lithium-containing brines in evaporation ponds. Once the lithium concentration reaches an appropriate level, processes such as boron removal and the removal of magnesium and calcium are carried out. Afterwards, soda ash is added to cause lithium to precipitate out in the form of lithium carbonate. II. The solvent extraction production process involves drying the brine from salt lakes in solar evaporation ponds, thereby gradually precipitating sodium chloride, halite, and some chloromagnesite. The resulting concentrated brine is acidified before being fed into the extraction tank. TBP (tributyl phosphate) is used as the extractant, HCl as the anti-extractant, and FeCl3 as a complexing agent. Through multiple stages of countercurrent extraction, washing, anti-extraction, and acid washing, the raffinate is discharged, while the organic phase is recycled for use in the extraction process. The resulting anti-extraction solution undergoes processes such as concentration, calcination, leaching, and impurity removal in the final product production stage, followed by evaporation for concentration and precipitation with soda ash to produce lithium carbonate products. III. The aluminate precipitation process: This method utilizes amorphous aluminum salts to selectively precipitate the substances present in brine, thereby forming a complex of LiCl·2Al(OH)3·nH2O, and this allows for the separation and recovery of lithium. The resulting lithium-containing precipitate is calcined and leached to obtain a lithium chloride solution and alumina; impurities such as magnesium and calcium in the lithium chloride solution are removed using lime milk and soda ash, followed by evaporation and concentration. Adding a sodium carbonate solution then allows lithium carbonate to be produced. IV. Adsorption process: This production method first uses selective adsorbents to absorb lithium ions from brine, and then elutes these lithium ions, thereby separating them from other ions and facilitating their further processing and utilization. Used ones include aluminum salt adsorbents, antimonate adsorbents, layered adsorbents, and ion-exchange oxide adsorbents. V. The electrodialysis production process involves the use of one or multiple stages of electrodialyzers, along with anion and cation monovalent selective ion exchange membranes, to carry out a cyclic (continuous, partially continuous, or batch) process for lithium concentration. This results in the formation of a lithium-rich, low-magnesium brine; further purification and concentration, along with conversion and drying, enable the production of lithium carbonate products.