Method for preparing battery-grade lithium carbonate from lithium sulfate crude ores and recovering byproducts

Abstract

The invention discloses a method for preparing battery-grade lithium carbonate from lithium sulfate crude ores and recovering byproducts. The method comprises the following steps: preparing battery-grade lithium carbonate; preparing mixed salt of gypsum, bischofite and borate; and preparing salt cake. According to the method, lithium chloride mother liquor generated by lithium precipitation and asodium sulfate solution are adopted for primary pulp washing, so that the loss of lithium sulfate can be reduced, and the recovery rate is increased; a recycled solution L4 containing lithium carbonate is taken as a pulp washing solution to carry out secondary pulp washing, soluble calcium and magnesium ions are removed, and lithium in the recycled solution is recovered; the filtrate L5 obtained after solid-liquid separation of the secondary pulp washing contains lithium, and is returned to the primary pulp washing as supplement, the loss of the primary pulp washing is reduced while soluble impurity ions are dissolved; the secondary lithium sulfate concentrate is dissolved by mirabilite preparation mother liquor L6, NaCl mixed salt is separated out in the dissolving process, and lithium isprecipitated. According to the method, the crude lithium carbonate is subjected to pulp washing by adopting the recycling solution containing lithium carbonate, so that the lithium yield can be increased while the system discharge is reduced.

Description

technical field [0001] The invention belongs to the technical field of production and preparation of lithium carbonate, and in particular relates to a method for preparing battery-grade lithium carbonate by using coarse lithium sulfate ore and recovering by-products. Background technique [0002] Lithium, known as the "energy upstart" in the 21st century, is the lightest and most active metal element in nature, and it is a new energy raw material. Lithium resources in nature mainly exist in granite pegmatite deposits, salt lake brine, sea water and geothermal water. [0003] The most difficult thing about developing salt lake resources in Tibet is that it is impossible to build chemical processing plants in the lake area, and it is far away from places with industrial processing capabilities. Therefore, high-grade minerals can only be obtained in the lake area and shipped out for processing. The environment obtains a series of salt pan minerals by building salt pans. [00...

AI Technical Summary

Problems solved by technology

[0005] At present, there are many kinds of studies on extracting lithium carbonate from salt lakes. For example, in the patent No. 201711113491.0 "a method for preparing battery-grade lithium carbonate from salt lake lithium ore", although the process is simple and battery-grade lithium carbonate is obtained, However, during the removal of impurities, the loss of lithium is relatively large, and its discharge is large, and resource recovery is not complete

Another example is the patent 201610212616.4 "Method for preparing lithium carbonate from plateau carbonate brine", which mainly uses the difference in local climate to design a series of impurity removal processes, but this process is highly dependent on the season and is only preliminary impurity removal. The lithium carbonate finally obtained has a low purity

Images