A method for preparing industry-grade basic magnesium carbonate for battery cathode materials from salt lake brine, which includes conversion coupling, solid-liquid separation, slurry washing, dehydration, drying and packaging steps, firstly mixing lithium carbonate electrodialysis separation tail liquid with lithium carbonate conversion tail liquid , carry out three-stage overflow-continuous conversion reaction; Then the mixed material liquid after the reaction is filtered, the solid phase basic magnesium carbonate filter cake obtained, the liquid phase is the lithium-containing waste liquid that discharges outside; The basic magnesium carbonate filter The cake is subjected to multiple pressure filtration dehydration and washing and grinding; the basic magnesium carbonate filter cake after washing is dehydrated to obtain the basic magnesium carbonate crude product; finally, the basic magnesium carbonate crude product is dried and pulverized, and then sealed and packaged.
Basic magnesium carbonate can be used as a battery positive electrode material, and it has the advantages of improving the performance of lithium batteries; in addition, this preparation method has the advantages of simple process, low production cost, high yield and good quality of the produced basic magnesium carbonate.
Hebei Messi Biology Co., Ltd. uses magnesium carbonate as a positive electrode material for batteries, and its application in the lithium battery industry has the following requirements:
First of all, it is necessary to control the main content of magnesium ions to stabilize. The main content of magnesium carbonate is controlled at 40-42%. The stability of the main content during production is conducive to the accurate addition of other materials. At present, for the production process and production technology level of domestic magnesium carbonate manufacturers, it is necessary to accurately control magnesium carbonate The lower limit of magnesium ion content is more difficult. If the product is not dried and the moisture content exceeds the standard, it will directly affect the problem of unstable magnesium ion content, and if the impurity control is unstable, it will also have adverse effects.
Secondly, the magnetic impurities should be controlled in a lower range. Magnetic impurities will affect the performance of the battery. It is necessary to control the magnetic impurities to less than 500 to be more stable. The detection method of magnetic impurities is a core technology in China, and only a few manufacturers can detect them. The core key of magnesium carbonate impurity removal process is the removal of magnetic impurities.
Finally, it is necessary to control the particle size span, and the span cannot be too large. Magnesium carbonate is generally tested with a laser particle size analyzer in China. The particle size D50 is about 2 microns, and D90 is about 20 microns. The finer is not the finer the better. The diameters are similar, all within the same span, which is more conducive to production.