阅读说明：本技术 一种用锂辉石和锂聚合物混合生产碳酸锂的工艺 (Process for producing lithium carbonate by mixing spodumene and lithium polymer ) 是由 何开茂 何东利 伍震洲 汪梨超 许小林 代道和 江莹 王晓洪 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,特别是一种用锂辉石和锂聚合物混合生产碳酸锂的工艺,包括以下步骤：将锂辉石和锂聚合物混合、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。本发明与传统的工艺相比较,用锂辉石和锂聚合物生产碳酸锂是以锂聚合物和锂辉石为原料,其中锂聚合物品位达到8.5％～12％(Li-2O),Al含量25.05％,Mg含量1.23％,Si含量0.84％,Mn含量0.69％,品位高且杂质含量少,是一种新型矿源,极具提取价值,具有极大的经济效益,同时也解决了锂辉石资源不足的困境。(The invention relates to the technical field of lithium carbonate production, in particular to a process for producing lithium carbonate by mixing spodumene and a lithium polymer, which comprises the following steps: mixing spodumene and lithium polymer, calcining, cooling, fine grinding, adding acid to make reaction, cooling, mixing slurry, leaching, press-filtering and separating, adding salt lake ore, cleaning, filtering, causticizing, freeze-separating sodium sulfate, evaporating and concentrating, carbonizing, centrifugal drying and jet-pulverizing so as to obtain the invented lithium carbonate. Compared with the traditional process, the method for producing the lithium carbonate by using the spodumene and the lithium polymer takes the lithium polymer and the spodumene as raw materials, wherein the grade of the lithium polymer reaches 8.5 to 12 percent (Li) 2 O), the Al content is 25.05 percent, the Mg content is 1.23 percent, the Si content is 0.84 percent, the Mn content is 0.69 percent, the grade is high, the impurity content is low, the method is a novel mineral source, the extraction value is high, the economic benefit is great, and the dilemma of insufficient spodumene resources is solved.)

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

s1, mixing spodumene and a lithium polymer according to a certain weight ratio, wherein the weight ratio of the lithium polymer: 1-3: 1, calcining, cooling, finely grinding, adding acid for reaction, cooling the product of the acid addition reaction to be less than or equal to 90 ℃, and then mixing the product with water to obtain slurry with the solid content of 10-70%;

s2, adding calcium carbonate slurry into the slurry obtained in the step S1, stirring and leaching, adjusting the temperature in a leaching tank to be less than or equal to 60 ℃ and the pH value to be 5.5-6, then adding calcium oxide to adjust the pH value to be 8-9, then filtering by using a filter press, purifying the filtered clear liquid by using lithium hydroxide mother liquor or calcium oxide, adjusting the pH value to be 9-12, and removing impurities of iron, manganese, aluminum and calcium in the filtered clear liquid;

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 of claim 1 for producing lithium carbonate from a mixture of spodumene and lithium polymer, wherein: in step S1, the calcination temperature is 950 to 1200 ℃ during calcination, the particle size of the fine grinding is required to be 200 meshes, sulfuric acid with a concentration of 98% is added during acid reaction, and the acid-to-material ratio is 2 to 4: 1, adding acid for reaction, and cooling to below 60 ℃.

3. A process for producing lithium carbonate from spodumene mixed with lithium polymer according to claim 1 or 2, characterized in that: and during cooling, the cooling is carried out in a water cooling mode.

4. The process of claim 1 for producing lithium carbonate from a mixture of spodumene and lithium polymer, wherein: in step S2, the solid content of the calcium carbonate slurry is 10-55%; adjusting the pH value of the added calcium oxide into powder with the mass fraction of more than 75% or slurry with the solid content of 10-55%; rinsing the filter cake filtered by the 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 to be used for size 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%.

5. The process of claim 1 for producing lithium carbonate from a mixture of spodumene and lithium polymer, 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.

6. The process of claim 1 for producing lithium carbonate from a mixture of spodumene and lithium polymer, wherein: in step S4, adding water into the causticized filter residue to prepare slurry with solid content of 10-70%, and returning to the step S2 for purification.

7. The process of claim 1 for producing lithium carbonate from a mixture of spodumene and lithium polymer, 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.

8. The process of claim 7 for producing lithium carbonate from a mixture of spodumene and lithium polymer, wherein: and the lithium sulfate finished solution is the lithium sulfate solution obtained by filtering filter residues after size mixing in the step S1.

9. The process of claim 1 for producing lithium carbonate from a mixture of spodumene and lithium polymer, 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 spodumene and a lithium polymer.

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 spodumene as a raw material, and lithium carbonate is obtained by 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.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a process for producing lithium carbonate by mixing spodumene and a lithium polymer, the process selects the spodumene and the lithium polymer as raw materials, the lithium polymer is a novel ore source, has high grade and high extraction value, has great economic benefit, solves the dilemma when the resources of the spodumene are insufficient, and increases the risk of resisting the resource insufficiency of a production line.

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

a process for producing lithium carbonate from a mixture of spodumene and a lithium polymer comprising the steps of:

s1, mixing spodumene and a lithium polymer according to a certain weight ratio, wherein the weight ratio of the lithium polymer: 1-3: 1, calcining, cooling, finely grinding, adding acid for reaction, cooling the product of the acid addition reaction to be less than or equal to 90 ℃, and then mixing the product with water to obtain slurry with the solid content of 10-70%;

s2, adding calcium carbonate slurry into the slurry obtained in the step S1, stirring and leaching, adjusting the temperature in a leaching tank to be less than or equal to 60 ℃ and the pH value to be 5.5-6, then adding calcium oxide to adjust the pH value to be 8-9, then filtering by using a filter press, purifying the filtered clear liquid by using lithium hydroxide mother liquor or calcium oxide, adjusting the pH value to be 9-12, and removing impurities of iron, manganese, aluminum and calcium in the filtered clear liquid;

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 calcination temperature is 950 to 1200 ℃, the particle size of the fine grinding is required to be 200 meshes, sulfuric acid with a concentration of 98% is added during the acid addition reaction, and the acid-to-material ratio is 2 to 4: 1, adding acid for reaction, and cooling to below 60 ℃.

Furthermore, during cooling, the cooling is carried out in a water cooling mode.

Further, in step S2, the solid content of the calcium carbonate slurry is 10% to 55%; adjusting the pH value of the added calcium oxide into powder with the mass fraction of more than 75% or slurry with the solid content of 10-55%; rinsing the filter cake filtered by the 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 to be used for size 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 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.

Further, in step S4, after adding water to the causticized filter residue to prepare slurry with a solid content of 10% to 70%, the process returns 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 invention selects spodumene and lithium polymer as raw materials, and the grade of the lithium polymer reaches 8.5-12% (Li)₂O), the Al content is 25.05 percent, the Mg content is 1.23 percent, the Si content is 0.84 percent, the Mn content is 0.69 percent, the ore source is a novel ore source, the grade is high, the extraction value is high, the economic benefit is great, the dilemma caused by insufficient lithium ore resources is solved, and the risk of resisting the insufficient resources of the production line is increased.

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 production cost is saved, 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.

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 a mixture of spodumene and lithium polymer, comprises the steps of:

s1, mixing spodumene and a lithium polymer according to a certain weight ratio, wherein the weight ratio of the lithium polymer: 1-3: 1, calcining, cooling, fine grinding, acid adding reaction and cooling in sequence, cooling a product of the acid adding reaction to be less than or equal to 90 ℃, then mixing the product with water to obtain slurry, wherein the solid content of the slurry is 10-70%, the calcining temperature is 950-1200 ℃, the granularity of the fine grinding is 200 meshes, sulfuric acid with the concentration of 98% is added during the acid adding reaction, and the acid-material ratio is 2-4: 1, more preferably, cooling to below 60 ℃ after the acid addition reaction, and cooling by adopting a water cooling mode during cooling;

s2, adding calcium carbonate slurry into the slurry obtained in the step S1, stirring and leaching, adjusting the temperature in a leaching tank to be less than or equal to 60 ℃ and the pH value to be 5.5-6, then adding calcium oxide to adjust the pH value to be 8-9, then filtering by using a filter press, purifying the filtered clear liquid by using lithium hydroxide mother liquor or calcium oxide, adjusting the pH value to be 9-12, and removing impurities of iron, manganese, aluminum and calcium in the filtered clear liquid; the solid content of the calcium carbonate slurry is 10-55 percent; adjusting the pH value of the added calcium oxide into powder with the mass fraction of more than 75% or slurry with the solid content of 10-55%; rinsing the filter cake filtered by the 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 to be used for size 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%;

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, 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 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, the causticized solution in the step S3 is carried out againFiltering to obtain causticized liquid and causticized filter residue, and 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 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, and 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.