阅读说明：本技术 一种电池级氢氧化锂的制备提纯方法 (Preparation and purification method of battery-grade lithium hydroxide ) 是由 张小江 吴再娟 周齐 陈竹林 于 2021-10-08 设计创作，主要内容包括：本发明提供一种电池级氢氧化锂的制备提纯方法,具体涉及到氢氧化锂生产技术领域。本发明包括如下步骤：向结晶器内充入不活泼的气体,排尽结晶器内原有的空气；向结晶器中加入氢氧化锂浓缩液,结晶器内的温度和压强均升高；结晶器抽至负压状态,结晶器内出现闪蒸现象,结晶器下部为液相段、上部为气相段：继续降低结晶器内的压强,使溶剂继续蒸发,杂质溶于溶剂中,氢氧化锂析出,直至杂质处于最大溶解度；再向结晶器内充入不活泼的气体,过滤排出滤液,取出结晶析出的氢氧化锂。本发明提出的一种电池级氢氧化锂的制备提纯方法,能够提高氢氧化锂制备的纯度和生产效率。(The invention provides a preparation and purification method of battery-grade lithium hydroxide, and particularly relates to the technical field of lithium hydroxide production. The invention comprises the following steps: filling inert gas into the crystallizer to exhaust the original air in the crystallizer; adding lithium hydroxide concentrated solution into a crystallizer, and increasing the temperature and pressure in the crystallizer; the crystallizer is pumped to a negative pressure state, a flash evaporation phenomenon occurs in the crystallizer, the lower part of the crystallizer is a liquid phase section, and the upper part of the crystallizer is a gas phase section: continuously reducing the pressure in the crystallizer to continuously evaporate the solvent, dissolving impurities in the solvent, and separating out lithium hydroxide until the impurities are in the maximum solubility; then filling inert gas into the crystallizer, filtering and discharging filtrate, and taking out lithium hydroxide precipitated by crystallization. The preparation and purification method of the battery-grade lithium hydroxide provided by the invention can improve the purity and production efficiency of the lithium hydroxide preparation.)

1. A preparation and purification method of battery-grade lithium hydroxide is characterized by comprising the following steps:

s1: filling inert gas into the crystallizer to exhaust the original air in the crystallizer;

s2: adding the lithium hydroxide concentrated solution into a crystallizer in S1, and increasing the temperature and pressure in the crystallizer;

s3: s2, pumping the crystallizer to a negative pressure state, wherein a flash evaporation phenomenon occurs in the crystallizer, the lower part of the crystallizer is a liquid phase section, and the upper part of the crystallizer is a gas phase section:

s4: continuously reducing the pressure in the crystallizer in S3 to continuously evaporate the solvent, dissolving impurities in the solvent, and separating out lithium hydroxide until the impurities are in the maximum solubility;

s5: then filling inert gas into the crystallizer, filtering and discharging filtrate, and taking out lithium hydroxide precipitated by crystallization.

2. The method for preparing and purifying battery-grade lithium hydroxide according to claim 1, wherein the method comprises the following steps: the inert gas in S1 and S5 is one or more of nitrogen, helium, neon, argon, krypton, and xenon.

3. The method for preparing and purifying battery-grade lithium hydroxide according to claim 1, wherein the method comprises the following steps: the temperature in the crystallizer in S2 is 40-60 ℃.

4. The method for preparing and purifying battery-grade lithium hydroxide according to claim 1, wherein the method comprises the following steps: the pressure in the crystallizer in S2 is 1.5-2.0 atmospheres.

5. The method for preparing and purifying battery-grade lithium hydroxide according to claim 1, wherein the method comprises the following steps: the pressure in the crystallizer in S3 was 0.5 atm.

6. The method for preparing and purifying battery-grade lithium hydroxide according to claim 1, wherein the method comprises the following steps: the pressure in the crystallizer is slowly reduced to 8000Pa in S4.

Technical Field

The invention belongs to the technical field of lithium hydroxide production, and particularly relates to a preparation and purification method of battery-grade lithium hydroxide.

Background

In the process of preparing battery-grade lithium hydroxide by evaporative crystallization, concentrated solution after evaporation is discharged to crystallization equipment, wet crystals are obtained and dried, and then a lithium hydroxide product can be obtained, wherein the control of a crystallization process has a great influence on the purity of the crystallized product. Therefore, a method for preparing and purifying battery-grade lithium hydroxide, which can solve the above problems, is needed.

Disclosure of Invention

The invention aims to provide a method for preparing and purifying battery-grade lithium hydroxide, which can improve the purity and production efficiency of lithium hydroxide preparation.

The invention provides the following technical scheme:

a preparation and purification method of battery-grade lithium hydroxide comprises the following steps:

s1: filling inert gas into the crystallizer to exhaust the original air in the crystallizer;

s2: adding the lithium hydroxide concentrated solution into a crystallizer in S1, and increasing the temperature and pressure in the crystallizer;

s3: s2, pumping the crystallizer to a negative pressure state, wherein a flash evaporation phenomenon occurs in the crystallizer, the lower part of the crystallizer is a liquid phase section, and the upper part of the crystallizer is a gas phase section:

s4: continuously reducing the pressure in the crystallizer in S3 to continuously evaporate the solvent, dissolving impurities in the solvent, and separating out lithium hydroxide until the impurities are in the maximum solubility;

s5: then filling inert gas into the crystallizer, filtering and discharging filtrate, and taking out lithium hydroxide precipitated by crystallization.

Preferably, the inactive gas in S1 and S5 is one or more of nitrogen, helium, neon, argon, krypton and xenon.

Preferably, the temperature in the crystallizer in S2 is 40-60 ℃.

Preferably, the pressure in the crystallizer in S2 is 1.5-2.0 atm.

Preferably, the pressure in the crystallizer in S3 is 0.5 atmosphere.

Preferably, the pressure in the crystallizer is slowly reduced to 8000Pa in S4.

The invention has the beneficial effects that:

the invention can prevent lithium hydroxide from reacting with carbon dioxide to generate impurities and influence the preparation purity of the lithium hydroxide by filling the inert gas;

lowering the boiling temperature of the solvent, lowering the solubility of lithium hydroxide (the solubility of lithium hydroxide decreases with decreasing temperature), resulting in a greater degree of supersaturation;

flash steam overflows from the concentrated solution, partial water is taken away, and the amount of a solvent is reduced, so that a larger supersaturation degree is generated, and more crystals are separated out;

the temperature reduction in the flash evaporation process is mild, and the problems that the impurity content of the product exceeds the standard and the like caused by the separation of impurities generated by rapid quenching and the entrainment of the impurities into the product are avoided.

Detailed Description

Example 1

A preparation and purification method of battery-grade lithium hydroxide comprises the following steps:

s1: filling nitrogen into the crystallizer, and exhausting the original air in the crystallizer;

s2: adding the lithium hydroxide concentrated solution into a crystallizer in S1, wherein the temperature in the crystallizer is increased to 40 ℃, and the pressure is increased to 1.5 atmospheric pressures;

s3: s2, the crystallizer is pumped to a negative pressure state through a vacuum pump, the pressure in the crystallizer is 0.5 atmosphere, the flash evaporation phenomenon occurs in the crystallizer, the lower part of the crystallizer is a liquid phase section, and the upper part of the crystallizer is a gas phase section:

s4: continuously reducing the pressure in the crystallizer in S3 to 8000Pa, continuously evaporating the solvent, dissolving impurities in the solvent, and separating out lithium hydroxide until the impurities are in the maximum solubility;

s5: then filling nitrogen into the crystallizer, filtering and discharging filtrate, and taking out lithium hydroxide precipitated by crystallization.

Example 2

A preparation and purification method of battery-grade lithium hydroxide comprises the following steps:

s1: filling nitrogen into the crystallizer, and exhausting the original air in the crystallizer;

s2: adding the lithium hydroxide concentrated solution into a crystallizer in S1, wherein the temperature in the crystallizer is increased to 50 ℃, and the pressure is increased to 1.75 atmospheric pressures;

s3: s2, the crystallizer is pumped to a negative pressure state through a vacuum pump, the pressure in the crystallizer is 0.5 atmosphere, the flash evaporation phenomenon occurs in the crystallizer, the lower part of the crystallizer is a liquid phase section, and the upper part of the crystallizer is a gas phase section:

s4: continuously reducing the pressure in the crystallizer in S3 to 8000Pa, continuously evaporating the solvent, dissolving impurities in the solvent, and separating out lithium hydroxide until the impurities are in the maximum solubility;

s5: then filling nitrogen into the crystallizer, filtering and discharging filtrate, and taking out lithium hydroxide precipitated by crystallization.

Example 3

A preparation and purification method of battery-grade lithium hydroxide comprises the following steps:

s1: filling nitrogen into the crystallizer, and exhausting the original air in the crystallizer;

s2: adding the lithium hydroxide concentrated solution into a crystallizer in S1, wherein the temperature in the crystallizer is increased to 60 ℃, and the pressure is increased to 2.0 atmospheric pressure;

s3: s2, the crystallizer is pumped to a negative pressure state through a vacuum pump, the pressure in the crystallizer is 0.5 atmosphere, the flash evaporation phenomenon occurs in the crystallizer, the lower part of the crystallizer is a liquid phase section, and the upper part of the crystallizer is a gas phase section:

s4: continuously reducing the pressure in the crystallizer in S3 to 8000Pa, continuously evaporating the solvent, dissolving impurities in the solvent, and separating out lithium hydroxide until the impurities are in the maximum solubility;

s5: then filling nitrogen into the crystallizer, filtering and discharging filtrate, and taking out lithium hydroxide precipitated by crystallization.

The lithium hydroxide precipitation ratio of embodiment 2 of the invention is the largest; inert gas is filled in the lithium hydroxide, so that the lithium hydroxide can be prevented from reacting with carbon dioxide to generate impurities, and the preparation purity of the lithium hydroxide is influenced; lowering the boiling temperature of the solvent, lowering the solubility of lithium hydroxide (the solubility of lithium hydroxide decreases with decreasing temperature), resulting in a greater degree of supersaturation; flash steam overflows from the concentrated solution, partial water is taken away, and the amount of a solvent is reduced, so that a larger supersaturation degree is generated, and more crystals are separated out; the temperature reduction in the flash evaporation process is mild, and the problems that the impurity content of the product exceeds the standard and the like caused by the separation of impurities generated by rapid quenching and the entrainment of the impurities into the product are avoided.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.