阅读说明：本技术 一种用盐湖矿石生产碳酸锂的工艺 (Process for producing lithium carbonate by using salt lake ore ) 是由 何开茂 何东利 伍震洲 汪梨超 杨贤丽 江莹 代道和 谭培渊 黄剑新 于 2021-01-21 设计创作，主要内容包括：本发明涉及碳酸锂生产技术领域,特别是一种用盐湖矿石生产碳酸锂的工艺,包括以下步骤：将盐湖矿石与水混合调浆、净化除杂、苛化除杂、冷冻除硫酸钠、蒸发、浓缩、离心干燥、气流粉碎、包装等,最终指的碳酸锂。本发明的优点在于：用盐湖矿石生产生产碳酸锂的工艺是以盐湖矿石为原料,盐湖矿石Li-2SO-4·H-2O含量达到80.1～92.1％,平均含量为85.1％。该工艺用盐湖矿石生产碳酸锂,解决了当锂矿石资源不足的困境,增加生产线抵抗资源不足的风险,同时解决了盐湖矿石资源生产碳酸锂品质低的问题。(The invention relates to the technical field of lithium carbonate production, in particular to a process for producing lithium carbonate by using salt lake ores, which comprises the following steps: mixing salt lake ore with water, pulping, purifying, causticizing, removing sodium sulfate by freezing, evaporating, concentrating, centrifugally drying, jet milling, packaging and the like, namely lithium carbonate. The invention has the advantages that: the process for producing lithium carbonate by using salt lake ore takes salt lake ore as raw material, and the salt lake ore Li 2 SO 4 ·H 2 The content of O is 80.1-92.1%, and the average content is 85.1%. The process for producing the lithium carbonate by using the salt lake ore solves the problem that the lithium ore resource is insufficient, increases the risk of resisting the insufficient resource of the production line, and simultaneously solves the problem of low quality of the lithium carbonate produced by using the salt lake ore resource.)

1. A process for producing lithium carbonate by using salt lake ores is characterized by comprising the following steps: the method comprises the following steps:

s1, mixing water with salt lake ore, wherein Li₂The concentration of O is 30-45 g/L, the mixed and size-mixed liquid is purified by lithium hydroxide mother liquor or calcium oxide, the pH value is adjusted to 9-12, and impurities of iron, manganese, aluminum and calcium in the filtered clear liquid are removed; then filtering by using a filter press to obtain filtered clear liquid;

s2, filtering the clear filtrate obtained in the step S1 again to obtain purified liquid and purified filter residues, causticizing the purified liquid by using 50% alkaline solution or crude product mother liquor, wherein the pH value of the causticized solution is 11-14, and the temperature is normal temperature;

s3, filtering the causticized solution obtained in the step S2 to obtain causticized liquid and causticized filter residue, and oxidizing hydrogen in the causticized liquidLithium Li₂Controlling the equivalent content of O to be 30-75 g/L, and filtering the causticized liquid through a precision filter to remove part of calcium ions;

s4, freezing and separating the filtered causticized liquid into sodium sulfate decahydrate and lithium hydroxide solution in a freezing workshop, wherein the freezing temperature is-5 to-20 ℃;

s5, purifying sodium sulfate decahydrate through evaporation concentration, heating to take out crystal water to obtain anhydrous sodium sulfate, heating to 200-800 ℃, filtering the lithium hydroxide solution through a precision filter to remove a part of calcium ions, then carrying out evaporation concentration, crystallizing, centrifuging, re-melting and filtering the concentrated crude lithium hydroxide solution through the precision filter, and then carrying out evaporation concentration through MVR to obtain a fine lithium hydroxide slurry;

s6, centrifugally separating and dissolving the fine lithium hydroxide slurry obtained in the step S5, then feeding the fine lithium hydroxide slurry into a carbonization kettle, introducing carbon dioxide gas with the pressure of 0.5MPa to perform carbonization reaction, keeping the gauge pressure in the carbonization kettle at 0.06-0.08 MPa, keeping the temperature at 48-52 ℃, and after the reaction is finished, closing the carbon dioxide and opening an emptying valve of the carbonization kettle to empty excessive carbon dioxide;

s7, centrifugally separating the carbonization reaction liquid obtained in the step S6 to obtain solid lithium carbonate, and drying to enable the water content of the solid lithium carbonate to be less than or equal to 5%;

and S8, conveying the centrifugal solid phase to a disc type dryer through a closed conveyor for drying, conveying the dried material to a lithium carbonate finished product warehouse through pneumatic conveying, conveying the material discharged from the disc type dryer to a raw material distribution system, stacking the material through an airflow crushing system and an automatic packaging system, and feeding the material into a finished product warehouse, wherein the finished product controls the magnetic substance not to exceed 30 PPb.

2. The process for producing lithium carbonate from salt lake ore according to claim 1, wherein: in step S1, during purification, if a lithium hydroxide mother liquor is added, the concentration of the lithium hydroxide mother liquor is 10% to 50%, and if calcium oxide is added, the calcium oxide is powder with a mass fraction of more than 75% or calcium oxide slurry with a solid content of 10% to 55%.

3. The process for producing lithium carbonate from salt lake ore according to claim 1, wherein: and step S1, rinsing the filter cake filtered by the filter press by using tap water or process water to ensure that the water content of the filter cake is less than or equal to 20%, and returning the rinsing water to be used in the size mixing procedure of the step S1.

4. The process for producing lithium carbonate from salt lake ore according to claim 1, wherein: in step S2, the filter residue is purified and added with water to be prepared into slurry with solid content of 10-70%, and then the slurry is returned to the slurry preparation process in step S1.

5. The process for producing lithium carbonate from salt lake ore according to claim 1, wherein: in step S3, adding water into the causticized filter residue to prepare slurry with solid content of 10-70%, and then returning to the purification process of step S2.

6. The process for producing lithium carbonate from salt lake ore according to claim 1, wherein: in step S7, the centrifuged liquid obtained by centrifugal separation contains a small amount of lithium carbonate, and the centrifuged liquid is pumped back to the slurry mixing step in the lithium sulfate finished liquid production section.

7. The process for producing lithium carbonate from salt lake ore according to claim 1, wherein: in step S8, the moisture content of the dried material is less than 0.2%.

8. The process for producing lithium carbonate from salt lake ore according to claim 6, wherein: and the lithium sulfate finished solution is the lithium sulfate solution obtained by filtering filter residues after size mixing in the step S1.

Technical Field

The invention relates to the technical field of lithium carbonate production, in particular to a process for producing lithium carbonate by using salt lake ores.

Background

Lithium carbonate can be used for preparing ceramics, medicaments, catalysts and the like. The common lithium ion battery raw material. As a positive electrode material of a lithium ion battery, high-purity lithium carbonate used as an electrolyte is receiving more and more attention. The existing method for producing lithium carbonate comprises the steps of producing lithium carbonate by taking spodumene as a raw material, extracting lithium from salt lake brine and extracting lithium carbonate from seawater. The process takes salt lake ore as a raw material, and the lithium carbonate is produced by the process steps of size mixing, leaching, squeezing and separating, freezing and separating sodium sulfate, evaporating, carbonizing, centrifugally drying and the like.

However, spodumene is insufficient in resources, and a new mineral source needs to be searched to meet the production requirement. Salt lake ore Li₂SO₄·H₂The content of O is 80.1-92.1%, the average content is 85.1%, in the prior art, lithium products produced by salt lake ores are only industrial grade generally, and the economic restriction factors for producing battery grade products from the path are more.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a process for producing lithium carbonate by using salt lake ores, which solves the dilemma of insufficient lithium ore resources, increases the risk of resisting the insufficient resources of a production line, shortens the production line and saves the equipment cost.

The purpose of the invention is realized by the following technical scheme:

a process for producing lithium carbonate by using salt lake ores comprises the following steps:

s1, mixing water withMixing salt lake ore, wherein Li₂The concentration of O is 30-45 g/L, the mixed and size-mixed liquid is purified by lithium hydroxide mother liquor or calcium oxide, the pH value is adjusted to 9-12, and impurities of iron, manganese, aluminum and calcium in the filtered clear liquid are removed; then filtering by using a filter press to obtain filtered clear liquid;

s2, filtering the clear filtrate obtained in the step S1 again to obtain purified liquid and purified filter residues, causticizing the purified liquid by using 50% alkaline solution or crude product mother liquor, wherein the pH value of the causticized solution is 11-14, and the temperature is normal temperature;

s3, filtering the causticized solution obtained in the step S2 to obtain causticized liquid and causticized filter residue, wherein lithium hydroxide Li in the causticized liquid₂Controlling the equivalent content of O to be 30-75 g/L, and filtering the causticized liquid through a precision filter to remove part of calcium ions;

s4, freezing and separating the filtered causticized liquid into sodium sulfate decahydrate and lithium hydroxide solution in a freezing workshop, wherein the freezing temperature is-5 to-20 ℃;

s5, purifying sodium sulfate decahydrate through evaporation concentration, heating to take out crystal water to obtain anhydrous sodium sulfate, heating to 200-800 ℃, filtering the lithium hydroxide solution through a precision filter to remove a part of calcium ions, then carrying out evaporation concentration, crystallizing, centrifuging, re-melting and filtering the concentrated crude lithium hydroxide solution through the precision filter, and then carrying out evaporation concentration through MVR to obtain a fine lithium hydroxide slurry;

s6, centrifugally separating and dissolving the fine lithium hydroxide slurry obtained in the step S5, then feeding the fine lithium hydroxide slurry into a carbonization kettle, introducing carbon dioxide gas with the pressure of 0.5MPa to perform carbonization reaction, keeping the gauge pressure in the carbonization kettle at 0.06-0.08 MPa, keeping the temperature at 48-52 ℃, and after the reaction is finished, closing the carbon dioxide and opening an emptying valve of the carbonization kettle to empty excessive carbon dioxide;

s7, centrifugally separating the carbonization reaction liquid obtained in the step S6 to obtain solid lithium carbonate, and drying to enable the water content of the solid lithium carbonate to be less than or equal to 5%;

and S8, conveying the centrifugal solid phase to a disc type dryer through a closed conveyor for drying, conveying the dried material to a lithium carbonate finished product warehouse through pneumatic conveying, conveying the material discharged from the disc type dryer to a raw material distribution system, stacking the material through an airflow crushing system and an automatic packaging system, and feeding the material into a finished product warehouse, wherein the finished product controls the magnetic substance not to exceed 30 PPb.

Further, in step S1, during the purification, if a lithium hydroxide mother liquor is added, the concentration of the lithium hydroxide mother liquor is 10% to 50%, and if calcium oxide is added, the calcium oxide is powder with a mass fraction of more than 75% or calcium oxide slurry with a solid content of 10% to 55%.

Further, in step S1, the filter cake filtered by the filter press is rinsed with tap water or process water to make the water content of the filter cake less than or equal to 20%, and the rinsing water is returned to the slurry mixing process in step S1.

Further, in step S2, the filter residue is purified and added with water to prepare a slurry with a solid content of 10% to 70%, and then the slurry is returned to the slurry mixing process in step S1.

Further, in step S3, the causticized filter residue is added with water to prepare slurry with a solid content of 10% to 70%, and then the process returns to the purification process of step S2.

Further, in step S7, the centrifuged liquid obtained by centrifugal separation contains a small amount of lithium carbonate, and the centrifuged liquid is pumped back to the slurry mixing step in the lithium sulfate finished liquid production section.

Further, in step S8, the moisture content of the dried material is less than 0.2%.

Further, the lithium sulfate finished solution is the lithium sulfate solution obtained by filtering the filter residue after size mixing in step S1.

The invention has the following advantages:

1. the process for producing lithium carbonate by using salt lake ore takes salt lake ore as raw material, and the salt lake ore Li₂SO₄·H₂The content of O is 80.1-92.1%, and the average content is 85.1%. The process for producing the lithium carbonate by using the salt lake ore solves the problem that the lithium ore resource is insufficient, increases the risk of resisting the insufficient resource of the production line, and simultaneously solves the problem of low quality of the lithium carbonate produced by using the salt lake ore resource.

2. The improvement of the process can precipitate most of impurity ions such as Fe, Cu, Zn, Al and the like in the leaching stage, and filter the leached filter residue as a filter cake.

3. The lithium hydroxide mother liquor is used for purification, so that the introduction of calcium ions can be greatly reduced, the content of the calcium ions in the product is reduced, the quality of the lithium hydroxide product is improved, meanwhile, calcium oxide is properly used as a purifying agent, calcium salt can be used as a filter cake in a filter pressing step, the impurity removal effect of purification is improved, and part of impurities are removed.

4. The lithium hydroxide mother liquor is used for causticizing instead of liquid caustic soda, so that the using amount of the liquid caustic soda can be reduced, the generation cost is saved, the external moisture is reduced, the circulation of water in a system is greatly reduced, and the operation cost is saved.

5. The adjusted leaching process can reduce the use amount of calcium carbonate, thereby reducing the generation amount of carbon dioxide, enabling the leaching reaction to become mild, and avoiding the potential safety hazards such as overflowing caused by a large amount of bubbles.

6. The main component of the salt lake ore is lithium sulfate which can be directly purified and causticized, thereby reducing the introduction of calcium ions in the leaching link, reducing the content of the calcium ions in the product and improving the grade of the product; and meanwhile, the mother liquor containing the chloride ions is carbonized and precipitated to obtain industrial-grade lithium carbonate, the added value of the product is increased, and the mother liquor containing the chloride ions obtained by lithium precipitation is used for producing lithium chloride.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The invention will be further described with reference to the accompanying drawings, but the scope of the invention is not limited to the following.

As shown in fig. 1, a process for producing lithium carbonate from salt lake ore comprises the following steps:

s1, mixing water with salt lake ore, wherein Li₂The concentration of O is 30-45 g/L, the mixed and size-mixed liquid is purified by lithium hydroxide mother liquor or calcium oxide, the concentration of the lithium hydroxide mother liquor is 10-50% when the lithium hydroxide mother liquor is added during purification, and the concentration of the lithium hydroxide mother liquor is 10-50% when the lithium hydroxide mother liquor is addedWhen the calcium oxide is calcium oxide, the calcium oxide is powder with the mass fraction of more than 75% or calcium oxide slurry with the solid content of 10% -55%, the pH value is adjusted to 9-12, and impurities of iron, manganese, aluminum and calcium in the filtered clear liquid are removed; then filtering by using a filter press to obtain a filtered clear solution, rinsing the filter cake filtered by the filter press by using tap water or process water to ensure that the water content of the filter cake is less than or equal to 20%, and returning the rinsing water to be used in the slurry mixing procedure of the step S1;

s2, filtering the clear filtrate obtained in the step S1 again to obtain purified liquid and purified filter residues, causticizing the purified liquid by using 50% alkaline solution or crude product mother liquor, adjusting the pH of the causticized solution to 11-14 and the temperature to normal temperature, adding water into the purified filter residues to adjust the purified filter residues into slurry with the solid content of 10% -70%, and returning the slurry to the slurry adjusting process in the step S1;

s3, filtering the causticized solution obtained in the step S2 to obtain causticized liquid and causticized filter residue, wherein lithium hydroxide Li in the causticized liquid₂Controlling the equivalent content of O to be 30-75 g/L, filtering the causticized liquid through a precision filter to remove partial calcium ions, adding water into the causticized filter residue to prepare slurry with the solid content of 10-70%, and then returning to the purification process of the step S2;

s4, freezing and separating the filtered causticized liquid into sodium sulfate decahydrate and lithium hydroxide solution in a freezing workshop, wherein the freezing temperature is-5 to-20 ℃;

s5, purifying sodium sulfate decahydrate through evaporation concentration, heating to take out crystal water to obtain anhydrous sodium sulfate, heating to 200-800 ℃, filtering the lithium hydroxide solution through a precision filter to remove a part of calcium ions, then carrying out evaporation concentration, crystallizing, centrifuging, re-melting and filtering the concentrated crude lithium hydroxide solution through the precision filter, and then carrying out evaporation concentration through MVR to obtain a fine lithium hydroxide slurry;

s6, centrifugally separating and dissolving the fine lithium hydroxide slurry obtained in the step S5, then feeding the fine lithium hydroxide slurry into a carbonization kettle, introducing carbon dioxide gas with the pressure of 0.5MPa to perform carbonization reaction, keeping the gauge pressure in the carbonization kettle at 0.06-0.08 MPa, keeping the temperature at 48-52 ℃, and after the reaction is finished, closing the carbon dioxide and opening an emptying valve of the carbonization kettle to empty excessive carbon dioxide;

s7, centrifugally separating the carbonization reaction liquid obtained in the step S6 to obtain solid lithium carbonate, drying the solid lithium carbonate to enable the water content of the solid lithium carbonate to be less than or equal to 5%, centrifugally separating to obtain a centrifugal liquid phase containing a small amount of lithium carbonate, pumping the centrifugal liquid back to a size mixing process of a lithium sulfate finished liquid production section, wherein the lithium sulfate finished liquid is the lithium sulfate solution obtained in the step S1, and filtering filter residues after size mixing;

and S8, conveying the centrifugal solid phase to a disc type dryer through a closed conveyor for drying, wherein the moisture content of the dried material is lower than 0.2%, conveying the dried material to a lithium carbonate finished product warehouse through pneumatic conveying, conveying the material discharged from the disc type dryer to a raw material shunting system, stacking the material through a jet milling system and an automatic packaging system, and conveying the material to a finished product warehouse, wherein the finished product controls the magnetic substance to be not more than 30 PPb.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.