阅读说明：本技术 一种低成本电池级碳酸锂的制备方法 (Preparation method of low-cost battery-grade lithium carbonate ) 是由 王维 张威风 刘海涛 李玉芝 刘海洋 于 2020-12-28 设计创作，主要内容包括：本发明公开了一种低成本电池级碳酸锂的制备方法,该制备方法是以锂辉石或锂云母矿石中提锂、盐湖卤水或地下卤水中提锂以及丁基锂生产过程产生锂渣为原料,经过破碎、筛分、与碳酸盐混匀、机械研磨和沉积等工序生成碳酸锂、碳分和煅烧等工序,具有工艺稳定、成本低等特点。(The invention discloses a preparation method of low-cost battery-grade lithium carbonate, which takes lithium extraction from spodumene or lepidolite ore, lithium extraction from salt lake brine or underground brine and lithium slag generated in the production process of butyl lithium as raw materials, and generates lithium carbonate, carbon content, calcination and other processes through the processes of crushing, screening, uniformly mixing with carbonate, mechanical grinding, deposition and the like, and has the characteristics of stable process, low cost and the like.)

1. A preparation method of low-cost battery-grade lithium carbonate is characterized by comprising the following steps:

(1) coarse crushing, ball milling and screening the lithium slag to ensure that the lithium slag with the granularity lower than 100 meshes accounts for more than 80 percent of the total lithium slag;

(2) uniformly mixing the screened lithium slag and carbonate according to the mass ratio of 5:1, and then fully mechanically grinding;

(3) and (3) adding deionized water into the powder obtained after mechanical grinding in the step (2) to obtain a powder with a solid-to-liquid ratio of 1: (1-2) reacting the suspension at 90-95 ℃ for 1h, and filtering by using a suction filter to obtain filter residue;

(4) and (3) adding deionized water into the filter residue obtained in the step (3) at room temperature to obtain a mixture with a solid-to-liquid ratio of 1: (2-3) and introducing excessive CO into the suspension₂；

(5) Filtering the turbid liquid obtained in the step (4), removing filter residues, heating the filtrate to 70-75 ℃, and then vacuumizing, wherein the vacuum degree is maintained at 0.2-0.25 atm for 1 hour;

(6) and (5) carrying out suction filtration on the solid-liquid mixture obtained in the step (5) to obtain Li₂CO₃Washing the crude product with deionized water to remove Li₂CO₃Soluble impurity ions in the crude product are dried for 2 hours at the temperature of 100-105 ℃, and Li with the purity higher than 99.9 percent is obtained₂CO₃And (5) producing the product.

2. The method for preparing low-cost battery-grade lithium carbonate according to claim 1, wherein the method comprises the following steps: the lithium slag used in the step (1) is produced in the production process of extracting lithium from spodumene or lepidolite ore, extracting lithium from salt lake brine or underground brine or butyl lithium.

3. The method for preparing low-cost battery-grade lithium carbonate according to claim 2, wherein the method comprises the following steps: the lithium slag comprises the following main components in percentage by weight: 8 to 12% of an oxide or compound of Li, Mg (OH)₂ 15~20%、CaSO₄ 25~30%、SiO₂35~40%、B₂O₃ 3~5%。

4. The method for preparing low-cost battery-grade lithium carbonate according to claim 3, wherein the method comprises the following steps: oxidation of LiThe substance or compound comprises LiOH, LiCl, Li₂CO₃Or Li₂O。

5. The method for preparing low-cost battery-grade lithium carbonate according to claim 3, wherein the method comprises the following steps: the filter residue obtained in the step (3) is Li₂CO₃、MgCO₃、CaCO₃、SiO₂And B₂O₃A mixture of (a).

6. The method for preparing low-cost battery-grade lithium carbonate according to claim 1, wherein the method comprises the following steps: the carbonate used in the step (2) is one or two of potassium carbonate and sodium carbonate.

7. The method for preparing low-cost battery-grade lithium carbonate according to claim 1, wherein the method comprises the following steps: the filtrate obtained in step (3) may be used to dissolve the mechanically ground powder in the next preparation of lithium carbonate.

Technical Field

The invention relates to the technical field of battery-grade lithium carbonate preparation, in particular to a preparation method of low-cost battery-grade lithium carbonate.

Background

Lithium resources exist mainly in the form of salt lakes and spodumene ores. Spodumene slag is one of industrial solid wastes, is industrial solid waste residue generated after lithium carbonate is extracted from spodumene ore industrially, has very large yield of spodumene slag at home and abroad, and a small part of unreacted metal lithium exists in residual liquid in the production process of butyl lithium, is hydrolyzed to become lithium hydroxide, and is discharged together with lithium chloride as lithium slag. The slag after the lithium extraction from the salt lake brine contains lithium chloride. If not used, the method not only occupies a large space for stacking, but also is inconvenient to manage, and residue water containing a certain amount of acid or alkali is easy to lose after being washed by rainwater, thus harming the surrounding farmlands and causing pollution. There is currently a lack of treatment routes for these lithium slags.

Lithium carbonate (Li)₂CO₃) It can be used as fluxing agent and additive in the course of glass production and ceramic production, also can be used as intermediate raw material for producing other lithium salts, for example, for producing surface elastic wave element material lithium tantalate and lithium niobate monocrystal, etc. In recent years, with the exposure of high-quality lithium salt in high and new technical fields such as new energy and new materials, particularly in the field of electric automobiles, lithium carbonate shows an attractive application prospect.

At present, the technology for producing lithium carbonate by taking spodumene as a raw material comprises a limestone roasting method, a soda ash pressure cooking method, a transformation roasting-sulfuric acid method and the like, and the production processes have the defects of low product purity, narrow raw material source range and high cost.

Disclosure of Invention

In order to solve the defects in the prior art, the invention provides a preparation method of low-cost battery-grade lithium carbonate, which replaces more expensive and scarce lepidolite, solves the problem of high cost when LiOH is directly used as a raw material, reduces the production cost of lithium carbonate, and has the advantages of stable process and simple preparation method.

In order to achieve the purpose, the invention adopts the specific scheme that:

a preparation method of low-cost battery-grade lithium carbonate is characterized by comprising the following steps:

(1) coarse crushing, ball milling and screening the lithium slag to ensure that the lithium slag with the granularity lower than 100 meshes accounts for more than 80 percent of the total lithium slag;

(2) uniformly mixing the screened lithium slag and carbonate according to the mass ratio of 5:1, and then fully mechanically grinding;

(3) and (3) adding deionized water into the powder obtained after mechanical grinding in the step (2) to obtain a powder with a solid-to-liquid ratio of 1: (1-2) reacting the suspension at 90-95 ℃ for 1h, and filtering by using a suction filter to obtain filter residue;

(4) and (3) adding deionized water into the filter residue obtained in the step (3) at room temperature to obtain a mixture with a solid-to-liquid ratio of 1: (2-3) and introducing excessive CO into the suspension₂；

(5) Filtering the turbid liquid obtained in the step (4), removing filter residues, heating the filtrate to 70-75 ℃, and then vacuumizing, wherein the vacuum degree is maintained at 0.2-0.25 atm for 1 hour;

(6) and (5) carrying out suction filtration on the solid-liquid mixture obtained in the step (5) to obtain Li₂CO₃Washing the crude product with deionized water to remove Li₂CO₃Soluble impurity ions in the crude product are dried for 2 hours at the temperature of 100-105 ℃, and Li with the purity higher than 99.9 percent is obtained₂CO₃And (5) producing the product.

Further, the lithium slag used in the step (1) is produced in the production process of extracting lithium from spodumene or lepidolite ore, extracting lithium from salt lake brine or underground brine or butyl lithium.

Further, the main components and contents of the lithium slag are as follows: 8 to 12% of an oxide or compound of Li, Mg (OH)₂15～20％、CaSO₄25～30％、SiO₂35～40％、B₂O₃3～5％。

Further, oxides or compounds of Li include LiOH, LiCl, Li₂CO₃Or Li₂O。

Further, the filter residue obtained in the step (3) is Li₂CO₃、MgCO₃、CaCO₃、SiO₂And B₂O₃A mixture of (a).

Further, the carbonate used in the step (2) is any one or two of potassium carbonate and sodium carbonate.

Further, the filtrate obtained in the step (3) may be used for dissolving the powder after mechanical grinding at the next preparation of lithium carbonate.

Has the advantages that:

1. according to the invention, the lithium carbonate product is produced by taking the lithium extracted from spodumene or lepidolite ore, the lithium extracted from salt lake brine or underground brine and the lithium slag generated in the butyl lithium production process as main raw materials, so that expensive and scarce lepidolite is replaced, the problem of high cost when LiOH is directly used as a raw material is solved, and the production cost of lithium carbonate is reduced.

2. The production process of the invention has easy control of solid-liquid reaction and liquid-liquid reactionNo complex equipment is needed, the operability is strong, the process is simple, the product purity is up to 99.9 percent, and the impurity content is as follows: na (Na)<0.014％，Ca<0.0018％，K<0.003％，Mg<0.033％，SO₄ ^2-<0.041 percent, improves the market competitiveness.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, belong to the scope of the present invention.

The invention provides a preparation method of low-cost battery-grade lithium carbonate, which takes lithium extracted from spodumene or lepidolite ore, lithium extracted from salt lake brine or underground brine and lithium slag generated in the production process of butyl lithium as raw materials, wherein the lithium slag comprises the following main components in percentage by weight: LiOH, LiCl, Li₂CO₃Or Li₂O：8～12％，Mg(OH)₂:15～20％，CaSO₄:25～30％，SiO₂:35～40％，B₂O₃3-5%, through crushing, screening, mixing with carbonate, mechanical grinding and deposition, etc., to generate lithium carbonate, carbon, calcination, etc., and has the characteristics of stable process, low cost, etc.

A preparation method of low-cost battery-grade lithium carbonate comprises the following steps:

(1) placing the lithium slag into a jaw crusher or a vertical crusher for coarse crushing, and performing ball milling and screening on the coarse crushed lithium slag to ensure that the lithium slag with the granularity lower than 100 meshes accounts for more than 80% of the total lithium slag;

(2) and uniformly mixing the screened lithium slag and carbonate according to the mass ratio of 5:1, and fully mechanically grinding in a planetary ball mill. Wherein the carbonate is one or two of potassium carbonate and sodium carbonate. The chemical reaction that takes place in this step (as exemplified with sodium carbonate only):

2LiCl+Na₂CO₃＝Li₂CO₃+2NaCl；

(3) adding deionized water into the ground powder obtained in the step (2) to obtain a suspension with a solid-to-liquid ratio of 1 (1-2), reacting for 1h at 90-95 ℃, filtering by using a suction filter, and taking filter residue as Li₂CO₃、MgCO₃、CaCO₃、SiO₂And B₂O₃The filtrate can be used for dissolving and grinding the powder for the next time. The chemical reaction that takes place in this step:

Li₂O+H₂O＝2LiOH；

2LiOH+Na₂CO₃＝Li₂CO₃+2NaOH；

(4) and adding deionized water into the filter residue obtained in the third step at room temperature to obtain a suspension with the solid-to-liquid ratio of 1 (2-3), introducing excessive carbon dioxide into the suspension, and carrying out main chemical reaction in the step:

Li₂CO₃+CO₂+H₂O＝2LiHCO₃；

CaCO₃+CO₂+H₂O＝Ca(HCO₃)₂；

MgCO₃+CO2+H₂O＝Mg(HCO₃)₂；

(5) filtering the turbid liquid obtained in the fourth step, discarding filter residues, heating the filtrate to 70-75 ℃, then vacuumizing, maintaining the vacuum degree at 0.2-0.25 atm for 1h, and carrying out main chemical reaction in the step:

2LiHCO₃＝Li₂CO₃+CO₂+H₂O；

Ca(HCO₃)₂＝CaCO₃+CO₂+H₂O；

CaCO₃＝CaO+CO₂；

Mg(HCO₃)₂＝MgCO₃+CO₂+H₂O；

MgCO₃＝MgO+CO₂；

(6) and (5) carrying out suction filtration on the solid-liquid mixture obtained in the step (5) to obtain Li₂CO₃Washing the crude product with deionized water to remove Li₂CO₃Soluble impurity ions in the crude product are dried for 2 hours at the temperature of 100-105 ℃ to obtainTo a purity of more than 99.9% Li₂CO₃And (5) producing the product.

Example 1

A low-cost lithium carbonate preparation method comprises the following steps:

(1) respectively weighing a certain amount of lithium slag and sodium carbonate for later use;

(2) coarsely crushing the lithium slag into particles with the particle size of less than 10mm by a crusher; ball-milling in a ball mill for 4h, and then sieving with a 100-mesh sieve;

(3) adding sodium carbonate into the lithium slag (minus 100 meshes is not less than 80%) sieved in the step (2) according to the mass ratio of the lithium slag to the sodium carbonate of 5:1, and performing ball milling for 4 hours in a planetary ball mill;

(4) adding deionized water into the powder after ball milling in the step (3) to obtain a suspension with a solid-to-liquid ratio of 1:1, reacting for 1h at 90-95 ℃, and filtering by using a suction filter to obtain filter residue;

(5) adding deionized water into the filter residue obtained in the step (4) to obtain a suspension with the solid-to-liquid ratio of 1:2, and introducing excessive carbon dioxide into the suspension;

(6) filtering the suspension obtained in the step (5), removing filter residues, heating the filtrate to 75 ℃, and then vacuumizing, wherein the vacuum degree is maintained at 0.2atm for 1 h;

(7) and (4) carrying out suction filtration on the solid-liquid mixture obtained in the step (6) to obtain Li₂CO₃Washing the crude product with deionized water to remove Li₂CO₃Soluble impurity ions in the crude product are dried for 2 hours at 100 ℃ to obtain the product with the purity higher than that of Li₂CO₃And (5) producing the product.

For the obtained Li₂CO₃Analysis of the composition of the product, Li obtained in this example₂CO₃The product indexes are as follows: li₂CO₃：99.9％，Na：0.014％，Ca：0.001％，K：0.001％，Mg：0.023％，SO₄ ^2-：0.024％。

Example 2

A low-cost lithium carbonate preparation method comprises the following steps:

(1) respectively weighing a certain amount of lithium slag and potassium carbonate for later use;

(2) coarsely crushing the lithium slag into particles with the particle size of less than 10mm by a crusher; ball-milling in a ball mill for 4h, and then sieving with a 100-mesh sieve;

(3) adding potassium carbonate into the lithium slag (the content of the 100 meshes is not less than 80%) sieved in the step (2) according to the mass ratio of the lithium slag to the potassium carbonate of 5:1, and performing ball milling for 4 hours in a planetary ball mill;

(4) adding deionized water into the powder obtained after grinding in the step (3) to obtain a suspension with a solid-to-liquid ratio of 1:2, reacting for 1h at 95 ℃, and filtering by a suction filter to obtain filter residue for later use;

(5) adding deionized water into the filter residue obtained in the step (4) according to the solution solid-liquid ratio of 1:3, and introducing excessive carbon dioxide into the solution;

(6) filtering the suspension obtained in the step (5), removing filter residues, heating the filtrate to 75 ℃, and then vacuumizing, wherein the vacuum degree is maintained at 0.25atm for 1 h;

(7) and (4) carrying out suction filtration on the solid-liquid mixture obtained in the step (6) to obtain Li₂CO₃Washing the crude product with deionized water to remove Li₂CO₃Soluble impurity ions in the crude product are dried for 2 hours at 105 ℃ to obtain the product with the purity higher than that of Li₂CO₃And (5) producing the product.

For the obtained Li₂CO₃Analysis of the composition of the product, Li obtained in this example₂CO₃The product indexes are as follows: li₂CO₃：99.9％，Na：0.011％，Ca：0.001％，K：0.003％，Mg：0.024％，SO₄ ^2-：0.022％。

In conclusion, the preparation method provided by the invention adopts low-cost lithium slag for preparation, is simple to operate, and can obtain a lithium carbonate product with high purity.

The foregoing is merely a preferred embodiment of the invention and is not to be construed as limiting the invention in any way. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.