Method for preparing lithium carbonate from plateau carbonate bittern

Abstract

The invention provides a method for preparing lithium carbonate from plateau carbonate bittern. The method comprises the following steps: subjecting original carbonate bittern A to evaporation before autumn and winter, adjusting the concentration of lithium ions so as to allow the lithium ions not to be precipitated in the form of minerals and introducing the carbonate bittern A to a deep-pool salt field for evaporation when the concentration of lithium ions reaches 1.2 to 1.8 g / L; as considerable mirabilite decahydrate is precipitated at first when temperature is -15 to -5 DEG C and the concentration of lithium ions rapidly increases, carrying out solid-liquid separation so as to obtain bittern B when the concentration of sulfate ions decreases to 4 to 7 g / L and the concentration of lithium ions increases to 2.6 to 3.5 g / L; introducing the bittern B into a heating system for heating to 20 to 60 DEG C, allowing a first batch of lithium carbonate concentrate and bittern C to be precipitated; subjecting the bittern C to refrigeration at a temperature of -20 DEG C or below so as to realize precipitation of mixed salt I and carrying out solid-liquid separation when the concentration of sulfate ions decreases to 15 g / L or below and the concentration of lithium ions increases to 2 g / L or above so as to obtain bittern D; and continuing evaporating the bittern D, adding bittern with a carbonate ion concentration of 60 g / L or above when the concentration of lithium ions reaches 2.6 to 3.5 g / L again and carrying out heating to 20 to 60 DEG C so as to allow a second batch of lithium carbonate concentrate to be precipitated.

Description

technical field [0001] The invention relates to a method for developing and utilizing carbonate-type brine, in particular to a method for preparing lithium carbonate from plateau carbonate-type brine. Background technique [0002] 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. [0003] There are two types of boron-rich lithium salt lakes in Tibet: carbonate type and sulfate type. In the early stage, for the development of sulfate-type boron-rich lithium salt lakes, the main process of freezing denitrification-evaporation potassium precipitation-dilution into salt precipitation boron-evaporation lithium precipitation was propose...

AI Technical Summary

Problems solved by technology

For the development of carbonate-type boron-rich lithium salt lakes, the problem is that due to the solubility of lithium carbonate, it is difficult to enrich lithium carbonate to a higher concentration. The process developed by Zabuye uses freezing denitrification-evaporation enrichment Lithium-Using the process of raising the temperature of solar pool to analyze lithium carbonate, this process realizes clean production and obtains better lithium carbonate minerals, but the enrichment degree of lithium ions in brine is low, which limits the yield of lithium precipitation; solar pool The operation is cumbersome and the production cycle is long; other resources except lithium have not been utilized

With the help of the geographical location of Jiezechaka (carbonate type) and Longmu Co (sulfate type) lakes (about 70km in a straight line), two boron-rich lithium salt lake brines, carbonate type and sulfate type, were developed. The coupled process can solve the problems of high magnesium / lithium ratio in sulfate-type salt lakes and difficult enrichment of lithium in carbonate-type salt lakes, and enrich lithium to a higher concentration. However, on the one hand, the two After all, the number of salt lakes is limited; on the other hand, the coupled development of the two salt lakes consumes a large amount of carbonate and produces a large amount of magnesium carbonate, which leads to the fact that carbonate-type salt lakes may not be able to provide sufficient carbonate for the production of lithium carbonate, which is harmful to salt lake resources. The stable production of

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