A kind of method directly preparing battery grade lithium carbonate

Abstract

The invention provides a method for directly preparing battery-grade lithium carbonate, comprising the following steps: step 1): adding sodium hydroxide solution to the lithium-containing solution, so that the pH of the entire solution reaches more than 12, and initially removing impurity metal ions in the solution , filter to obtain the first refined lithium solution; step 2): add dilute acid to the first refined lithium solution, and adjust the pH value to less than or equal to 3 to obtain the second refined lithium solution; step 3): add the second refined lithium solution Add a chelating agent to the solution, then add sodium hydroxide solution to adjust the pH of the solution to 6-8 to obtain the third refined lithium solution; step 4): add sodium carbonate solution to the third refined lithium solution, heat to form a precipitate, and the resulting precipitate Filter, wash, and dry to obtain battery-grade lithium carbonate. In the method, dilute acid is first used to reverse the pH value, and then sodium ethylenediamine di-o-phenyl acetate is used to complex metal impurity elements, and then NaOH is used to reverse the pH value, so that residual metal impurity elements are well removed, and the purity of lithium carbonate is improved.

Description

technical field [0001] The invention belongs to the field of inorganic chemistry and relates to a separation and extraction process of inorganic substances, in particular to a preparation method of battery-grade lithium carbonate. Background technique [0002] There are currently three main production methods for battery-grade lithium carbonate. The first is the causticization method, which is to remove calcium, magnesium and other impurities through the causticization method of lime milk and industrial grade lithium carbonate, and the filtrate is LiOH solution, and LiOH·H 2 O crystals, at this time, CO is introduced into the solution 2 , and finally high-purity lithium carbonate precipitates are obtained. This method has relatively strict requirements on condition control such as temperature, reaction ratio, and time, and is not suitable for large-scale production. The second is the hydrogenation method, which is also a commonly used method at present. It is to mix the c...

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Problems solved by technology

This method has strict requirements on condition control such as temperature, reaction ratio, time, etc., and is not suitable for large-scale production

The second is the hydrogenation method, which is also a commonly used method at present. It is to mix the crude lithium carbonate and water in a certain ratio, control a certain temperature, and feed high-purity carbon dioxide into the slurry for a certain period of time until the lithium carbonate slurry is completely converted into Lithium bicarbonate solution, through filtration, impurity removal and other processes to obtain a clear lithium bicarbonate solution, and then through alkali precipitation or thermal decomposition to obtain high-purity lithium carbonate, this method has low reaction requirements and is suitable for industrial production, but due to CO 2 Insufficient utilization leads to low efficiency

The third is the complexation impurity removal method, which is to add a complexing agent to complex the impurity ions before and during the hydrogenation treatment. Because the complexes are easily soluble in water, the cations in the insoluble calcium and magnesium salts are converted into Complexes are used to achieve the purpose of removing impurities. This method requires more than 6 times the amount of complexed ions, and the cost is relatively high.