阅读说明：本技术 一种用锂聚合物和盐湖矿石混合生产碳酸锂的工艺 (Process for producing lithium carbonate by mixing lithium polymer and salt lake ore ) 是由 何开茂 何东利 伍震洲 汪梨超 江莹 代道和 杨贤丽 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,特别是一种用锂聚合物和盐湖矿石混合生产碳酸锂的工艺,包括以下步骤：将锂聚合物依次经过煅烧、冷却、细磨、加酸反应、冷却、调浆、浸出,压滤机压榨分离,加入盐湖矿石,净化、过滤、苛化,再冷冻分离硫酸钠,蒸发浓缩、碳化、离心干燥、气流粉碎等工艺步骤而得碳酸锂。本发明将盐湖矿石和锂聚合物混合生产碳酸锂,锂聚合物是一种新型矿源,极具提取价值,具有极大的经济效益,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氢氧化锂品质低的问题,采用品质更高的锂聚合物作为原料,在前期处理时,工艺条件相比于用锂辉石作为原料时的工艺条件更加宽泛。(The invention relates to the technical field of lithium carbonate production, in particular to a process for producing lithium carbonate by mixing lithium polymer and salt lake ore, which comprises the following steps: the lithium polymer is sequentially subjected to the process steps of calcining, cooling, fine grinding, acid adding reaction, cooling, slurry mixing, leaching, press filtering and separation, salt lake ore addition, purification, filtration, causticization, freezing separation of sodium sulfate, evaporation concentration, carbonization, centrifugal drying, jet milling and the like to obtain the lithium carbonate. According to the invention, salt lake ore and lithium polymer are mixed to produce lithium carbonate, the lithium polymer is a novel ore source, has great extraction value and great economic benefit, the dilemma that the lithium ore resource is insufficient is solved, the risk that the production line resists the insufficient resource is increased, and the problem that the quality of lithium hydroxide produced by the salt lake ore resource is low is solved.)

1. A process for producing lithium carbonate by mixing lithium polymer and salt lake ore is characterized in that: the method comprises the following steps:

s1, sequentially calcining, cooling, finely grinding, adding acid for reaction and cooling the lithium polymer, cooling the product of the acid reaction to be less than or equal to 90 ℃, and then adding water to prepare slurry with the solid content of 10-70%;

s2, adding calcium salt slurry into the slurry obtained in the step S1, stirring and leaching, adding calcium oxide to adjust the pH to 8-9 after leaching for 20 minutes at the temperature of less than or equal to 60 ℃ in a leaching tank and the pH of more than or equal to 5, then filtering by using a filter press, adding salt lake ore into the filtered clear liquid, and controlling the mixed material Li₂The concentration of O is 30-48 g/L, the 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;

s3, filtering the clear filtrate obtained in the step S2 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;

s4, filtering the solution causticized in the step S3 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;

s5, 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 ℃;

s6, 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;

s7, centrifugally separating and dissolving the fine lithium hydroxide slurry obtained in the step S6, 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 ℃, stopping introducing carbon dioxide after the reaction is finished and keeping the pressure stable, and opening an emptying valve of the carbonization kettle to empty excessive carbon dioxide to obtain carbonization reaction liquid;

s8, centrifugally separating the carbonization reaction liquid obtained in the step S7 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 S9, 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 by mixing lithium polymer and salt lake ore according to claim 1, wherein: in the step S1, the requirement of the fine grinding granularity is 200 meshes, and the calcining temperature is 1000-1250 ℃; and (3) adding sulfuric acid with the concentration of 98% during acid adding reaction, wherein the acid-material ratio is 2-5: 1, adding acid for reaction, and cooling to below 60 ℃; and during cooling, the cooling is carried out in a water cooling mode.

3. The process for producing lithium carbonate by mixing lithium polymer and salt lake ore according to claim 1, wherein: in step S2, the solid content of the calcium salt slurry is 10-55%; rinsing a filter cake obtained by filtering through a filter press by using tap water or process water, blowing the filter cake by using compressed air to ensure that the water content of the filter cake is less than or equal to 20%, and returning rinsing water for slurry mixing in the step S1; during purification, if lithium hydroxide mother liquor is added, the concentration of the lithium hydroxide mother liquor is 10-50%, and if calcium oxide is added, the calcium oxide is powder with the mass fraction of more than 75% or calcium oxide slurry with the solid content of 10-55%.

4. The process for producing lithium carbonate by mixing lithium polymer and salt lake ore according to claim 1, wherein: in the step S3, adding water into the purified filter residue to prepare slurry with the solid content of 10-70%, and returning to the step S1; the alkaline solution is sodium hydroxide solution, lithium hydroxide solution or the mixed solution of the sodium hydroxide solution and the lithium hydroxide solution.

5. The process for producing lithium carbonate by mixing lithium polymer and salt lake ore according to claim 1, wherein: in step S4, adding water into the causticized filter residue to prepare slurry with the solid content of 10-70%, and then returning to the step S2 for purification.

6. The process for producing lithium carbonate by mixing lithium polymer and salt lake ore according to claim 1, wherein: in step S8, 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 by mixing lithium polymer and 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.

8. The process for producing lithium carbonate by mixing lithium polymer and salt lake ore according to claim 1, wherein: in step S9, the moisture content of the dried material is less than 0.2%.

Technical Field

The invention relates to the technical field of lithium carbonate production, in particular to a process for producing lithium carbonate by mixing lithium polymer and salt lake ore.

Background

Lithium carbonate can be used for preparing ceramics, medicaments, catalysts and the like, and is also a commonly used raw material of a lithium ion battery. 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 spodumene and salt lake ores as raw materials, and produces the lithium carbonate through the process steps of high-temperature calcination transformation, cooling, ball milling, acidification roasting, cooling, size mixing, leaching, squeezing and separation, sodium sulfate freezing separation, evaporation, carbonization, centrifugal 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.

The spodumene is used as a raw material to prepare the lithium carbonate, and the raw material quality is not high, the process condition is severer, the production difficulty is high, more waste residues are generated, and the resource utilization rate is low.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a process for producing lithium carbonate by mixing a lithium polymer and salt lake ores.

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

a process for producing lithium carbonate by mixing lithium polymer and salt lake ore comprises the following steps:

s1, sequentially calcining, cooling, finely grinding, adding acid for reaction and cooling the lithium polymer, cooling the product of the acid reaction to be less than or equal to 90 ℃, and then adding water to prepare slurry with the solid content of 10-70%;

s2, adding calcium salt slurry into the slurry obtained in the step S1, stirring and leaching, adding calcium oxide to adjust the pH to 8-9 after leaching for 20 minutes at the temperature of less than or equal to 60 ℃ in a leaching tank and the pH of more than or equal to 5, then filtering by using a filter press, adding salt lake ore into the filtered clear liquid, and controlling the mixed material Li₂The concentration of O is 30-48 g/L, the 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;

s3, filtering the clear filtrate obtained in the step S2 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;

s4, filtering the solution causticized in the step S3 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;

s5, 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 ℃;

s6, 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;

s7, centrifugally separating and dissolving the fine lithium hydroxide slurry obtained in the step S6, 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 ℃, stopping introducing carbon dioxide after the reaction is finished and keeping the pressure stable, and opening an emptying valve of the carbonization kettle to empty excessive carbon dioxide to obtain carbonization reaction liquid;

s8, centrifugally separating the carbonization reaction liquid obtained in the step S7 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 S9, 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, the requirement of the fine grinding granularity is 200 meshes, and the calcining temperature is 1000-1250 ℃; and (3) adding sulfuric acid with the concentration of 98% during acid adding reaction, wherein the acid-material ratio is 2-5: 1, adding acid for reaction, and cooling to below 60 ℃; and during cooling, the cooling is carried out in a water cooling mode.

Further, in step S2, the solid content of the calcium salt slurry is 10% to 55%; rinsing a filter cake obtained by filtering through a filter press by using tap water or process water, blowing the filter cake by using compressed air to ensure that the water content of the filter cake is less than or equal to 20%, and returning rinsing water for slurry mixing in the step S1; during purification, if lithium hydroxide mother liquor is added, the concentration of the lithium hydroxide mother liquor is 10-50%, and if calcium oxide is added, the calcium oxide is powder with the mass fraction of more than 75% or calcium oxide slurry with the solid content of 10-55%.

Further, in step S3, adding water into the purified filter residue to prepare slurry with the solid content of 10% -70%, and returning to step S1; the alkaline solution is sodium hydroxide solution, lithium hydroxide solution or the mixed solution of the sodium hydroxide solution and the lithium hydroxide solution.

Further, in step S4, adding water into the causticized filter residue to prepare slurry with the solid content of 10-70%, and then returning to the step S2 for purification.

Further, in step S8, 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, the lithium sulfate finished solution is the lithium sulfate solution obtained by filtering the filter residue after size mixing in step S1.

Further, in step S9, the moisture content of the dried material is less than 0.2%.

The invention has the following advantages:

1. the lithium carbonate is produced by using lithium polymer and salt lake ore as raw materials and through the process steps of high-temperature calcination and transformation, cooling, ball milling, acidification roasting, cooling, size mixing, leaching, squeezing and separation, sodium sulfate freezing separation, evaporation, carbonization, centrifugal drying and the like, wherein the grade of the lithium polymer reaches 8.5% -12% (Li polymer grade)₂O), 25.05 percent of Al, 1.23 percent of Mg, 0.84 percent of Si and 0.69 percent of Mn, is a novel mineral source, has great extraction value and great economic benefit, and the salt lake ore Li₂SO₄·H₂The content of O is 80.1-92.1%, and the average content is 85.1%.

2. Compared with the process for producing lithium carbonate by using spodumene, the process has the advantages of high raw material grade, low impurity content and less generated waste residues, increases the utilization rate of resources and relieves the influence of spodumene tension on production.

3. The lithium polymer having higher quality is used as a raw material, and the process conditions in the preliminary treatment are broader than those in the case of spodumene.

4. The 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 being not easy to generate a large amount of bubbles to cause potential safety hazards such as overflowing and the like.

5. 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 schematic 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 by mixing lithium polymer and salt lake ore comprises the following steps:

s1, sequentially calcining, cooling, finely grinding, carrying out acid addition reaction and cooling on the lithium polymer, cooling a product of the acid addition reaction to be less than or equal to 90 ℃, and then mixing the product with water to obtain slurry, wherein the solid content of the slurry is 10-70%, the finely ground particle size is required to be 200 meshes, and the calcining temperature is 1000-1250 ℃; and (3) adding sulfuric acid with the concentration of 98% during acid adding reaction, wherein the acid-material ratio is 2-5: 1, more preferably, cooling to below 60 ℃ after the acid addition reaction; during cooling, the cooling is carried out in a water cooling mode;

s2, adding calcium salt slurry into the slurry obtained in the step S1, stirring and leaching, wherein the solid content of the calcium salt slurry is 10-55%; the temperature in the leaching tank is less than or equal to 60 ℃, the pH value is more than or equal to 5, calcium oxide is added after leaching for 20 minutes to adjust the pH value to 8-9, then a filter press is used for filtering, a filter cake obtained by filtering through the filter press is rinsed by tap water or process water, the filter cake is swept by compressed air, the water content of the filter cake is less than or equal to 20%, and the rinsing water is returned for size mixing in the step S1; adding salt lake ore into the filtered clear liquid, and controlling the mixed material Li₂The concentration of O is 30-48 g/L, the 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; during purification, if lithium hydroxide mother liquor is added, the concentration of the lithium hydroxide mother liquor is 10 percentAbout 50 percent, if calcium oxide is added, the calcium oxide is powder with the mass fraction of more than 75 percent or calcium oxide slurry with the solid content of 10 to 55 percent;

s3, filtering the clear filtrate obtained in the step S2 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; adding water into the purified filter residue to prepare slurry with the solid content of 10-70%, and returning to the step S1; the alkaline solution is sodium hydroxide solution, lithium hydroxide solution or the mixed solution of the sodium hydroxide solution and the lithium hydroxide solution;

s4, filtering the solution causticized in the step S3 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 step S2 for purification;

s5, 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 ℃;

s6, 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;

s7, centrifugally separating and dissolving the fine lithium hydroxide slurry obtained in the step S6, 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 ℃, stopping introducing carbon dioxide after the reaction is finished and keeping the pressure stable, and opening an emptying valve of the carbonization kettle to empty excessive carbon dioxide to obtain carbonization reaction liquid;

s8, centrifugally separating the carbonization reaction liquid obtained in the step S7 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 by filtering filter residues after size mixing;

and S9, 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.