Process for co-producing lithium carbonate and potassium salt with lithium-containing nanofiltration water

Abstract

The invention discloses a process for co-producing lithium carbonate and potassium salt with lithium-containing nanofiltration water. The process comprises the following steps: (1) separating magnesium sulfate subtype salt lake brine with a nano-filtering film to obtain the lithium-containing nanofiltration water; (2) distilling the lithium-containing nanofiltration water to obtain the finished product brine; (3) adsorbing and purifying the finished product brine with strong alkali anion exchange resin to obtain purified brine; (4) distilling the purified brine to obtain a sodium chloride refined salt and a salt-potassium co-saturated brine; (5) cooling and crystalizing the salt-potassium co-saturated brine to obtain industrial potassium chloride and lithium-enriched brine; (6) adding a carbonate solution into the lithium-enriched brine, precipitating and crystalizing at the temperature of 80 to 100 DEG C to obtain the finished product industrial lithium carbonate. By adopting the process, the magnesium sulfate subtype salt lake brine is adjusted, the salt field process is simplified, the crystallization and precipitation of mineral sulfate are avoided; the potassium salt machiningprocess is improved, lithium carbonate and potassium salt coproduction can be realized by further adsorption and purification.

Description

Technical field [0001] The present invention involves a process of preparing lithium carbonate and potassium salt and potassium, which specifically involves a process of lithium carbonate and potassium -producing potassium -produced water carbonate from lithium -containing lithium. Background technique [0002] my country is a country with many salt lakes, with magnesium sulfate sub -salt lakes the most widely distributed. At present, the comprehensive development and utilization of magnesium sulfate sub -salt lake brine resources at home and abroad is achieved through salt field natural stalls and evaporation crystals through salt field separation technology. Conditions passed through sodium chloride salt field-Xishinfield-potassium magnesium mixed salt field-potassium mixed salt field-light halogen salt field, and finally obtained old lithium-rich old halogen; most of them are sodium chloride as salt field waste salt stacked or Salt lake road infrastructure, etc., potassium mag...

AI Technical Summary

Problems solved by technology

[0004] CN1542147A discloses a nanofiltration method for separating magnesium and enriching lithium from salt lake brine, which uses a monovalent ion selective nanofiltration membrane to pass chloride-type lithium-containing salt lake brine through multi-stage nanofilters to realize divalent ions. Interception and enrichment of lithium, but the suitable raw brine is mostly lithium-rich brine with low magnesium and low salinity obtained after removing sodium and extracting potassium from the old brine through adsorption and separation of magnesium

CN103074502A discloses a salt lake brine treatment method for separating lithium from salt lake brine with high magnesium-lithium ratio, which is to use salt lake brine to obtain old brine through multi-stage salt field evaporation, and then chemically remove sulfate and magnesium in order to reduce the ratio of magnesium to lithium After dilution, the brine passes through a nanofiltration membrane device for magnesium-lithium separation to obtain lithium-rich water with a magnesium-lithium ratio of less than or equal to 2, and then undergoes reverse osmosis, deep magnesium removal, and salt field evaporation to obtain lithium-rich water with a lithium ion concentration of 33-38g / L Brine is used to produce high-purity lithium carbonate, but this process also has technical defects such as complicated process and large amount of fresh water dilution

CN106082284A discloses a production method of battery-grade high-purity lithium carbonate, which uses salt lake brine as a raw material to produce crystallized mother liquor wastewater after potassium chloride, and sequentially passes through ion exchange and adsorption, ultrafiltration membrane technology, and segmental nanofiltration technology. , ion exchange technology, reverse osmosis technology, and sun-drying lithium deposition to obtain battery-grade high-purity lithium carbonate also have technical defects such as high investment costs and complicated process flow

It can be seen that the nanofiltration lithium extraction process mostly uses the old brine from Yantian as the raw material, and sequentially obtains lithium-rich brine with a low magnesium-lithium ratio through adsorption + nanofiltration, and then produces lithium carbonate through concentration and deep impurity removal. The nanofiltration process is suitable for brine mineralization The density is low, mostly less than 50g / L. At present, there are few reports on the process or research on the direct nanofiltration separation of magnesium and the production of lithium carbonate from high salinity salt lake brine. At the same time, the utilization of lithium-containing nanofiltration water is also mostly Lithium carbonate is mainly produced, and the salt-potassium co-production process of sodium chloride and potassium chloride is not considered