Method for increasing recovery rate of lithium separated with lithium-containing brine membrane method by using water as circulating working substance (water washing circulation method)

Abstract

The invention relates to a method for increasing the recovery rate of lithium in salt lake brine, in particular to a method for increasing the recovery rate of lithium in a membrane method for separating magnesium and lithium from the salt lake brine with high salt content and high magnesium/lithium ratio and concentrated lithium-containing old brine obtained after potash fertilizer production in a salt pan. In the method, water is used as a circulating working substance to dilute raw material brine with high salt content and high magnesium/lithium ratio to be below 180g/l; the diluted raw material brine is divided into concentrated liquid and permeated liquid by means of a separation membrane driven under one-stage or multistage pressure, wherein the salt content in the concentrated liquid is equivalent to or higher than that of the raw materials brine, and the lithium in the permeated liquid accounts for about 2/3 of the lithium resources of a feed solution; and a reverse osmosis membrane system or a membrane distillation system is used to perform concentration and separation to obtain fresh water and concentrated water, wherein the fresh water is circulated for diluting the raw material brine, the concentrated water is precipitated for lithium carbonate recovery, and supernate obtained after precipitation is partially returned for diluting the raw material brine. The method disclosed by the invention can be used for obviously reducing the load of a separation membrane system, reducing the operation cost and increasing the recovery rate, so that the recovery rate of the lithium in the brine with high salt content is increased.

Description

technical field [0001] The invention relates to a method for improving the recovery rate of lithium in lithium-containing brine, especially for separating magnesium and enriching lithium from lithium-containing old brine after concentrated production of potassium fertilizer in salt lake brine with high salt content and high magnesium-lithium ratio in salt fields, so as to improve Lithium recovery method. technical background [0002] The problem of high magnesium and low lithium is common in salt lakes in western my country. The ratio of magnesium to lithium is usually 50:1 to 300:1. Too high to be applicable. [0003] Salt lakes in western my country mostly use the salt field method to produce potash fertilizers, and the old brine has a high salt content, especially the magnesium chloride is in a saturated state. In order to increase the concentration of lithium in the old brine and reduce the ratio of magnesium to lithium, the magnesium salt is usually crystallized by eva...

AI Technical Summary

Problems solved by technology

[0004] Disclosed in the Chinese patent 03108088.X is a nanofiltration method for separating magnesium and enriching lithium from salt lake brine. The method uses nanofiltration membrane method to separate magnesium and enrich lithium from salt lake brine, but due to In particular, the salt content in the old brine after the production of potassium fertilizer by the salt field method is high, and the direct use of the nanofiltration membrane method has the problems of high pressure and low recovery rate.