CN109179458B - Method for purifying industrial-grade lithium carbonate to battery-grade lithium carbonate - Google Patents
Method for purifying industrial-grade lithium carbonate to battery-grade lithium carbonate Download PDFInfo
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- CN109179458B CN109179458B CN201811354519.4A CN201811354519A CN109179458B CN 109179458 B CN109179458 B CN 109179458B CN 201811354519 A CN201811354519 A CN 201811354519A CN 109179458 B CN109179458 B CN 109179458B
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Abstract
The invention discloses a method for purifying industrial-grade lithium carbonate to battery-grade lithium carbonate, which comprises the steps of weighing a certain amount of pretreated lithium carbonate, adding the lithium carbonate into a screw crusher through a funnel, crushing the lithium carbonate by a screw, then feeding the lithium carbonate into a reaction kettle, and adding the lithium carbonate into the reaction kettleDeionized water was made into suspension and CO was controlled using rotameter2Flow rate of CO2Entering into lithium carbonate suspension, and then starting stirring by a first stirring device and heating a water tank for water bath heating; after the reaction is finished, the water pump starts to work, the mixed liquid is pumped into the filter box through the pipeline and is filtered through the first filter screen and the second filter screen, the purification method disclosed by the invention is characterized in that the pretreatment, the modified D751 chelating resin is added and a device is combined, the whole preparation process is simple, integrated and high in automation degree, the working efficiency is improved, the time is saved, and the purity of the prepared lithium carbonate crystal can reach 99.98%.
Description
Technical Field
The invention relates to the technical field of lithium carbonate, in particular to a method for purifying industrial-grade lithium carbonate to battery-grade lithium carbonate.
Background
Lithium carbonate is an inorganic compound, and is colorless monoclinic crystal or white powder, and has a chemical formula of Li2CO3. Soluble in dilute acid, slightly soluble in water, and more soluble in cold water than in hot water. Insoluble in alcohol and acetone. Density 2.11g/cm3723 deg.C (1.013 x 10) melting point5Pa) is added. Can be used for preparing ceramics, medicaments, catalysts and the like, and is a common lithium ion battery raw material. Lithium carbonate is an important chemical raw material, and with the development planning of new national energy, the new lithium battery energy is one of the national important support and development energy industries.
By electrolysis of industrial grade lithium carbonate, Li2CO3The high-purity lithium carbonate can be produced by recrystallization, carbonic acid hydrogenation decomposition, carbonic acid hydrogenation precipitation, sodium carbonate chemical precipitation and the like. For example, Chinese patent 200710019052.3 "A process for preparing high-purity lithium carbonate from salt lake lithium resource" features that the raw lithium carbonate prepared from salt lake brine is introduced into it by CO2Carbonizing, then performing various impurity removal processes, decomposing the lithium bicarbonate under the negative pressure condition, and leaching for multiple times to obtain the lithium carbonate with the purity of 99.9%.
However, the current preparation method still has the defects, wherein the most obvious problem is that the product purity and the impurity content are difficult to further improve, the purification method provided by the invention has the advantages that the whole preparation process is simple, the preparation process is integrated, the automation degree is high, the working efficiency is improved, the time is saved, and the purity of the prepared lithium carbonate crystal can reach 99.98% by carrying out pretreatment and adding modified D751 chelating resin and combining the devices.
Disclosure of Invention
In order to overcome the technical problems, the invention aims to provide a method for purifying industrial-grade lithium carbonate to battery-grade lithium carbonate, and the method for purifying the industrial-grade lithium carbonate to the battery-grade lithium carbonate has the advantages that the whole preparation process is simple, integrated and high in automation degree, the working efficiency is improved, the time is saved, and the purity of the prepared lithium carbonate crystals can reach 99.98% by carrying out pretreatment, adding modified D751 chelating resin and combining devices.
The purpose of the invention can be realized by the following technical scheme:
a purification method from industrial-grade lithium carbonate to battery-grade lithium carbonate is based on a purification device, and comprises the following steps:
1) carbonizing: weighing a certain amount of pretreated lithium carbonate, adding the lithium carbonate into a screw rod crusher through a funnel, crushing the lithium carbonate through a screw rod, then adding the lithium carbonate into a reaction kettle, adding deionized water into the reaction kettle to prepare suspension with the solid-to-liquid ratio of 20-30:1, and controlling CO by using a rotameter2Flow rate of CO2Entering the lithium carbonate suspension liquid through an air inlet pipe at the flow rate of 0.8-1.2L/min, and then starting stirring by a first stirring device and heating a water tank for water bath heating;
2) and (3) filtering: after the reaction is finished, the water pump starts to work, the mixed liquid is pumped into the filter box through the pipeline and is filtered through the first filter screen and the second filter screen;
3) ion exchange refining: mixing 748 resin solution and modified D751 chelating resin according to a ratio of 1:1, filling the mixture into an ion exchange column, and then enabling lithium carbonate suspension to flow through the ion exchange column at a flow rate of 0.04-0.07L/min;
4) and (3) pyrolysis reaction: the lithium carbonate suspension treated in the step 3) flows into a stirring box, amino acid crystals are added through a feeding hole, then the lithium carbonate suspension is stirred and mixed through a second stirring device, and is heated through a heating sheet arranged inside the stirring box to perform pyrolysis reaction;
5) drying treatment: and after pyrolysis is completed, opening the control valve, enabling the mixed solution to enter a filtering device, filtering through a third filter screen and a fourth filter screen, recycling the mother solution, wherein the filter cake is lithium carbonate crystals, washing the lithium carbonate crystals with deionized water for 2-5 times, removing impurities, and finally drying through a drying device to obtain the battery-grade lithium carbonate.
As a further scheme of the invention: the preparation method of the pretreated lithium carbonate comprises the following steps:
1) preparing a lithium chloride solution with the concentration of 3.2mol/L and a sodium carbonate solution with the concentration of 2.8mol/L, respectively filtering through a filter screen, adding the filtered lithium chloride solution into a reaction kettle of a full-automatic synthesis workstation, adding a 110% sodium carbonate solution into the reaction kettle according to the flow of 0.8-1L/min, and heating and stirring;
2) and after the feeding is finished, continuously keeping the original heating temperature and stirring speed for continuously reacting for 30min, then taking out the obtained turbid liquid, filtering by a filter screen in a suction filtration manner to obtain filter residues, namely lithium carbonate crystals, washing the filter residues for 2-5 times by deionized water, and drying in a drying box to obtain the pretreated lithium carbonate.
As a further scheme of the invention: the stirring speed is 550-650rpm, and the heating temperature is 75-85 ℃.
As a further scheme of the invention: the sodium carbonate solution is added into the reaction kettle in a reverse feeding mode.
As a further scheme of the invention: the preparation of the modified D751 chelating resin comprises the following steps:
1) connecting a fluorine gas cylinder and a nitrogen gas cylinder with the bottom of a glass exchange column through a pipeline, installing a flowmeter on the pipeline, and then connecting the top of the glass exchange column with two buffer bottles through another pipeline; firstly opening a nitrogen valve, replacing for 20 minutes by nitrogen, checking the tightness of each interface, then drying the D751 chelating resin at 80 ℃ until the water content is less than 10%, filling the dried D751 chelating resin into a glass exchange column with the height of 400mm, respectively adding 300mL of 1mol/L sodium hydroxide into 2 buffer bottles, installing rubber plugs, opening the nitrogen valve, replacing for 15 minutes by nitrogen, checking the air tightness, closing the nitrogen valve, carefully opening the valve of a fluorine gas bottle, slowly adjusting the flow of fluorine gas, starting timing, when a flowmeter shows zero, fully opening the valve of the fluorine gas bottle, keeping for 35 minutes, then opening the nitrogen valve, replacing for 20 minutes, and taking out the D751 chelating resin for later use;
2) and soaking the fluorinated D751 chelate tree in deionized water for 24 hours, and drying by spinning to obtain the modified D751 chelate resin.
As a further scheme of the invention: the heating temperature of the water bath is 15-25 ℃, and the stirring speed of the first stirring device is 350-450 rpm.
As a further scheme of the invention: the heating temperature of the heating sheet is 60-80 ℃, the stirring speed of the second stirring device is 450-550rpm, and the pyrolysis time is 4-6 hours.
The invention has the beneficial effects that:
1. by modifying the D751 chelating resin, when fluorine gas is contacted with a carbon-hydrogen bond in the D751 chelating resin, fluorine atoms replace hydrogen atoms in the carbon-hydrogen bond to perform fluorination reaction to form a carbon-fluorine bond structure layer, and a rubber elastomer is formed on the surface of the D751 chelating resin, so that the adsorption performance and the mechanical property of the D751 chelating resin are improved; and 748 resin and D751 chelating resin are mixed and used according to the ratio of 1:1, so that the purification effect is better than that of single use;
2. by pretreating lithium carbonate, adding 110% of sodium carbonate solution into a reaction kettle in a reverse feeding mode according to the flow of 1L/min, heating and stirring at the stirring speed of 600rpm and the heating temperature of 80 ℃, and filtering crystals, the purity of the lithium carbonate is improved and can reach 92.34%;
3. lithium carbonate is added into the screw crusher through a funnel,the screw crusher crushes the mixture to improve the dissolving efficiency and save the reaction time, and then the mixture enters a reaction kettle, deionized water is added and CO is introduced2The method comprises the following steps that a first stirring device starts to stir and heat a water bath by a heating water tank, then mixed liquid is pumped into a filter tank through a pipeline by a water pump, the mixed liquid is filtered by a first filter screen and a second filter screen to improve the purity of the mixed liquid, then impurities are removed from the mixed liquid through an ion exchange column to improve the purity of the mixed liquid, then the mixed liquid entering the stirring tank is stirred and mixed by a second stirring device, the mixed liquid is heated by a heating sheet arranged inside the stirring tank to carry out a pyrolysis reaction, and finally the mixed liquid is filtered by a third filter screen and a fourth filter screen to obtain lithium carbonate crystals; the whole preparation process is simple, integrated and high in automation degree, the working efficiency is improved, the time is saved, the purity of the prepared lithium carbonate crystal can reach 99.98%, and the yield can reach 97.6%.
Drawings
The invention will be further described with reference to the accompanying drawings.
FIG. 1 is a schematic view of the structure of a purification apparatus of the present invention.
In the figure: 1. a funnel; 2. a screw crusher; 3. heating the water tank; 4. a reaction kettle; 5. a first stirring device; 6. an air inlet pipe; 7. a pipeline; 8. a water pump; 9. a stirring box; 10. a filtration device; 11. a fourth filter screen; 12. a third filter screen; 13. a control valve; 14. a heating plate; 15. a second stirring device; 16. a feed inlet; 17. an ion exchange column; 18. a filter box; 19. a second filter screen; 20. a first filter screen; 21. a rotameter.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious 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 derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1:
as shown in fig. 1, a method for purifying industrial-grade lithium carbonate to battery-grade lithium carbonate is based on a purification device, and the purification method comprises the following steps:
1) carbonizing: weighing a certain amount of pretreated lithium carbonate, adding the lithium carbonate into a screw crusher 2 through a funnel 1, crushing the lithium carbonate through a screw, then adding the lithium carbonate into a reaction kettle 4, adding deionized water into the reaction kettle 4 to prepare suspension with the solid-to-liquid ratio of 20:1, and controlling CO by using a rotameter 212Flow rate of CO2The lithium carbonate suspension enters the lithium carbonate suspension through an air inlet pipe 6 at a flow rate of 1L/min, then a first stirring device 5 starts stirring and a heating water tank 3 carries out water bath heating, the water bath heating temperature is 20 ℃, and the stirring speed of the first stirring device 5 is 400 rpm;
2) and (3) filtering: after the reaction is finished, the water pump 8 starts to work, the mixed liquid is pumped into the filter tank 18 through the pipeline 7, and is filtered through the first filter screen 20 and the second filter screen 19;
3) ion exchange refining: the 748 resin solution and the modified D751 chelating resin are mixed and configured according to the ratio of 1:1, and are filled in the ion exchange column 17, and then the lithium carbonate suspension flows through the ion exchange column 17 at the flow rate of 0.05L/min;
4) and (3) pyrolysis reaction: the lithium carbonate suspension treated in the step 3) flows into the stirring box 9, amino acid crystals are added through the feeding hole 16, then the lithium carbonate suspension is stirred and mixed through the second stirring device 15, the lithium carbonate suspension is heated through the heating sheet 14 arranged inside the stirring box 9, the heating temperature of the heating sheet 14 is 70 ℃, the stirring speed of the second stirring device 15 is 500rpm, and the pyrolysis time is 5 hours;
5) drying treatment: after pyrolysis, the control valve 13 is opened, the mixed liquid enters the filtering device 10, the mixed liquid is filtered through the third filter screen 12 and the fourth filter screen 11, the mother liquid is recycled, the filter cake is lithium carbonate crystals, then the lithium carbonate crystals are washed for 3 times by deionized water, impurities are removed, and finally drying is carried out through the drying device, so that the battery-grade lithium carbonate is obtained.
The preparation method of the pretreated lithium carbonate comprises the following steps:
1) preparing a lithium chloride solution with the concentration of 3.2mol/L and a sodium carbonate solution with the concentration of 2.8mol/L, respectively filtering through a filter screen, adding the filtered lithium chloride solution into a reaction kettle of a full-automatic synthesis workstation, adding a 110% sodium carbonate solution into the reaction kettle in a reverse feeding mode according to the flow of 1L/min, and heating and stirring, wherein the stirring speed is 600rpm, and the heating temperature is 80 ℃;
2) and after the feeding is finished, continuously keeping the original heating temperature and the original stirring speed for continuously reacting for 30min, then taking out the obtained turbid liquid, filtering by a filter screen in a suction filtration manner, wherein filter residues are lithium carbonate crystals, washing the lithium carbonate crystals for 4 times by deionized water, and drying the lithium carbonate crystals in a drying box, so that the pretreated lithium carbonate can be obtained.
The preparation of the modified D751 chelating resin comprises the following steps:
1) connecting a fluorine gas cylinder and a nitrogen gas cylinder with the bottom of a glass exchange column through a pipeline, installing a flowmeter on the pipeline, and then connecting the top of the glass exchange column with two buffer bottles through another pipeline; firstly opening a nitrogen valve, replacing for 20 minutes by nitrogen, checking the tightness of each interface, then drying the D751 chelating resin at 80 ℃ until the water content is less than 10%, filling the dried D751 chelating resin into a glass exchange column with the height of 400mm, respectively adding 300mL of 1mol/L sodium hydroxide into 2 buffer bottles, installing rubber plugs, opening the nitrogen valve, replacing for 15 minutes by nitrogen, checking the air tightness, closing the nitrogen valve, carefully opening the valve of a fluorine gas bottle, slowly adjusting the flow of fluorine gas, starting timing, when a flowmeter shows zero, fully opening the valve of the fluorine gas bottle, keeping for 35 minutes, then opening the nitrogen valve, replacing for 20 minutes, and taking out the D751 chelating resin for later use;
2) and soaking the fluorinated D751 chelate tree in deionized water for 24 hours, and drying by spinning to obtain the modified D751 chelate resin.
Comparative example 1:
as shown in fig. 1, a method for purifying industrial-grade lithium carbonate to battery-grade lithium carbonate is based on a purification device, and the purification method comprises the following steps:
1) carbonizing: weighing a certain amount of pretreated lithium carbonate, adding the lithium carbonate into a screw crusher 2 through a funnel 1, crushing the lithium carbonate through a screw, then adding the lithium carbonate into a reaction kettle 4, adding deionized water into the reaction kettle 4 to prepare suspension with the solid-to-liquid ratio of 20:1, and controlling CO by using a rotameter 212Flow rate of CO2The lithium carbonate suspension enters the lithium carbonate suspension through an air inlet pipe 6 at a flow rate of 1L/min, then a first stirring device 5 starts stirring and a heating water tank 3 carries out water bath heating, the water bath heating temperature is 20 ℃, and the stirring speed of the first stirring device 5 is 400 rpm;
2) and (3) filtering: after the reaction is finished, the water pump 8 starts to work, the mixed liquid is pumped into the filter tank 18 through the pipeline 7, and is filtered through the first filter screen 20 and the second filter screen 19;
3) ion exchange refining: the 748 resin solution is filled in the ion exchange column 17, and then the lithium carbonate suspension flows through the ion exchange column 17 at the flow rate of 0.05L/min;
4) and (3) pyrolysis reaction: the lithium carbonate suspension treated in the step 3) flows into the stirring box 9, amino acid crystals are added through the feeding hole 16, then the lithium carbonate suspension is stirred and mixed through the second stirring device 15, the lithium carbonate suspension is heated through the heating sheet 14 arranged inside the stirring box 9, the heating temperature of the heating sheet 14 is 70 ℃, the stirring speed of the second stirring device 15 is 500rpm, and the pyrolysis time is 5 hours;
5) drying treatment: after pyrolysis, the control valve 13 is opened, the mixed liquid enters the filtering device 10, the mixed liquid is filtered through the third filter screen 12 and the fourth filter screen 11, the mother liquid is recycled, the filter cake is lithium carbonate crystals, then the lithium carbonate crystals are washed for 3 times by deionized water, impurities are removed, and finally drying is carried out through the drying device, so that the battery-grade lithium carbonate is obtained.
The preparation method of the pretreated lithium carbonate comprises the following steps:
1) preparing a lithium chloride solution with the concentration of 3.2mol/L and a sodium carbonate solution with the concentration of 2.8mol/L, respectively filtering through a filter screen, adding the filtered lithium chloride solution into a reaction kettle of a full-automatic synthesis workstation, adding a 110% sodium carbonate solution into the reaction kettle in a reverse feeding mode according to the flow of 1L/min, and heating and stirring, wherein the stirring speed is 600rpm, and the heating temperature is 80 ℃;
2) and after the feeding is finished, continuously keeping the original heating temperature and the original stirring speed for continuously reacting for 30min, then taking out the obtained turbid liquid, filtering by a filter screen in a suction filtration manner, wherein filter residues are lithium carbonate crystals, washing the lithium carbonate crystals for 4 times by deionized water, and drying the lithium carbonate crystals in a drying box, so that the pretreated lithium carbonate can be obtained.
Comparative example 2:
as shown in fig. 1, a method for purifying industrial-grade lithium carbonate to battery-grade lithium carbonate is based on a purification device, and the purification method comprises the following steps:
1) carbonizing: weighing a certain amount of lithium carbonate, adding the lithium carbonate into a screw crusher 2 through a funnel 1, crushing the lithium carbonate through a screw, then adding the lithium carbonate into a reaction kettle 4, adding deionized water into the reaction kettle 4 to prepare suspension with the solid-to-liquid ratio of 20:1, and controlling CO by using a rotameter 212Flow rate of CO2The lithium carbonate suspension enters the lithium carbonate suspension through an air inlet pipe 6 at a flow rate of 1L/min, then a first stirring device 5 starts stirring and a heating water tank 3 carries out water bath heating, the water bath heating temperature is 20 ℃, and the stirring speed of the first stirring device 5 is 400 rpm;
2) and (3) filtering: after the reaction is finished, the water pump 8 starts to work, the mixed liquid is pumped into the filter tank 18 through the pipeline 7, and is filtered through the first filter screen 20 and the second filter screen 19;
3) ion exchange refining: the 748 resin solution and the modified D751 chelating resin are mixed and configured according to the ratio of 1:1, and are filled in the ion exchange column 17, and then the lithium carbonate suspension flows through the ion exchange column 17 at the flow rate of 0.05L/min;
4) and (3) pyrolysis reaction: the lithium carbonate suspension treated in the step 3) flows into the stirring box 9, amino acid crystals are added through the feeding hole 16, then the lithium carbonate suspension is stirred and mixed through the second stirring device 15, the lithium carbonate suspension is heated through the heating sheet 14 arranged inside the stirring box 9, the heating temperature of the heating sheet 14 is 70 ℃, the stirring speed of the second stirring device 15 is 500rpm, and the pyrolysis time is 5 hours;
5) drying treatment: after pyrolysis, the control valve 13 is opened, the mixed liquid enters the filtering device 10, the mixed liquid is filtered through the third filter screen 12 and the fourth filter screen 11, the mother liquid is recycled, the filter cake is lithium carbonate crystals, then the lithium carbonate crystals are washed for 3 times by deionized water, impurities are removed, and finally drying is carried out through the drying device, so that the battery-grade lithium carbonate is obtained.
The preparation of the modified D751 chelating resin comprises the following steps:
1) connecting a fluorine gas cylinder and a nitrogen gas cylinder with the bottom of a glass exchange column through a pipeline, installing a flowmeter on the pipeline, and then connecting the top of the glass exchange column with two buffer bottles through another pipeline; firstly opening a nitrogen valve, replacing for 20 minutes by nitrogen, checking the tightness of each interface, then drying the D751 chelating resin at 80 ℃ until the water content is less than 10%, filling the dried D751 chelating resin into a glass exchange column with the height of 400mm, respectively adding 300mL of 1mol/L sodium hydroxide into 2 buffer bottles, installing rubber plugs, opening the nitrogen valve, replacing for 15 minutes by nitrogen, checking the air tightness, closing the nitrogen valve, carefully opening the valve of a fluorine gas bottle, slowly adjusting the flow of fluorine gas, starting timing, when a flowmeter shows zero, fully opening the valve of the fluorine gas bottle, keeping for 35 minutes, then opening the nitrogen valve, replacing for 20 minutes, and taking out the D751 chelating resin for later use;
2) and soaking the fluorinated D751 chelate tree in deionized water for 24 hours, and drying by spinning to obtain the modified D751 chelate resin.
Comparative example 3:
as shown in fig. 1, a method for purifying industrial-grade lithium carbonate to battery-grade lithium carbonate is based on a purification device, and the purification method comprises the following steps:
1) carbonizing: weighing a certain amount of lithium carbonate, adding the lithium carbonate into a screw crusher 2 through a funnel 1, crushing the lithium carbonate through a screw, then adding the lithium carbonate into a reaction kettle 4, adding deionized water into the reaction kettle 4 to prepare suspension with the solid-to-liquid ratio of 20:1, and controlling CO by using a rotameter 212Flow rate of CO2Enters into the lithium carbonate suspension through the air inlet pipe 6 at the flow rate of 1L/min, and then the first stirring device 5 is startedStarting stirring and heating the water tank 3 for water bath heating, wherein the water bath heating temperature is 20 ℃, and the stirring speed of the first stirring device 5 is 400 rpm;
2) and (3) filtering: after the reaction is finished, the water pump 8 starts to work, the mixed liquid is pumped into the filter tank 18 through the pipeline 7, and is filtered through the first filter screen 20 and the second filter screen 19;
3) ion exchange refining: the 748 resin solution is filled in the ion exchange column 17, and then the lithium carbonate suspension flows through the ion exchange column 17 at the flow rate of 0.05L/min;
4) and (3) pyrolysis reaction: the lithium carbonate suspension treated in the step 3) flows into the stirring box 9, amino acid crystals are added through the feeding hole 16, then the lithium carbonate suspension is stirred and mixed through the second stirring device 15, the lithium carbonate suspension is heated through the heating sheet 14 arranged inside the stirring box 9, the heating temperature of the heating sheet 14 is 70 ℃, the stirring speed of the second stirring device 15 is 500rpm, and the pyrolysis time is 5 hours;
5) drying treatment: after pyrolysis, the control valve 13 is opened, the mixed liquid enters the filtering device 10, the mixed liquid is filtered through the third filter screen 12 and the fourth filter screen 11, the mother liquid is recycled, the filter cake is lithium carbonate crystals, then the lithium carbonate crystals are washed for 3 times by deionized water, impurities are removed, and finally drying is carried out through the drying device, so that the battery-grade lithium carbonate is obtained.
The lithium carbonate prepared in example 1 and comparative examples 1 to 3 was subjected to a performance test, and the test results are shown in the following table:
TABLE 1
| Purity (%) | Ca2+(mg/L) | K+(mg/L) | Mg2+(mg/L) | Yield (%) | |
| Example 1 | 99.98 | 1.72 | 0.48 | 6.13 | 97.6 |
| Comparative example 1 | 91.21 | 2.48 | 0.63 | 7.86 | 92.5 |
| Comparative example 2 | 90.08 | 2.36 | 0.65 | 7.59 | 91.3 |
| Comparative example 3 | 82.12 | 3.55 | 0.78 | 8.58 | 88.9 |
As can be seen from the above table, the purity of the lithium carbonate prepared by the purification method can be foundTo reach 99.98%, yield can reach 97.6%, and Ca2+、K+、Mg2+The content of (A) is relatively low.
Example 2
As shown in fig. 1, the purification device comprises a funnel 1, a screw pulverizer 2, a heating water tank 3, a reaction kettle 4, a first stirring device 5, an air inlet pipe 6, a pipeline 7, a water pump 8, a stirring box 9, a filtering device 10, a fourth filtering net 11, a third filtering net 12, a control valve 13, a heating sheet 14, a second stirring device 15, a feed inlet 16, an ion exchange column 17, a filtering box 18, a second filtering net 19, a first filtering net 20 and a rotor flow meter 21, wherein one end of the top of the screw pulverizer 2 is fixedly connected with the funnel 1, a discharge port at one side of the screw pulverizer 2 is connected with a feed inlet arranged on the reaction kettle 4, one end of the top of the reaction kettle 4 is connected with the rotor flow meter 21 through an air inlet pipe 6, the rotor flow meter 21 controls the flow of carbon dioxide, the first stirring device 5 is arranged inside the reaction kettle 4 for stirring, the heating water tank, heating in water bath, wherein a pipeline 7 arranged in the reaction kettle 4 extends out of the reaction kettle 4, the pipeline 7 sequentially passes through a water pump 8 and a filter tank 18 to be connected with the top end of an ion exchange column 17, a first filter screen 20 and a second filter screen 19 are sequentially arranged in the filter tank 18 for filtering, the mesh number of the first filter screen 20 is twice that of the second filter screen 19, the filtering effect is good, the purity is improved, the bottom end of the ion exchange column 17 is fixedly connected with the stirring box 9, the top of the stirring box 9 is provided with a feeding hole 16, the stirring box 9 is internally provided with a second stirring device 15, both sides of the inner wall of the stirring box 9 are fixedly connected with heating sheets 14, the bottom opening of the stirring box 9 is connected with the filter box 18, a control valve 13 is arranged at the joint of the stirring box 9 and the filtering box 18, so that the opening and the discharging are convenient, and a third filtering net 12 and a fourth filtering net 11 are sequentially arranged on the filtering box 18 from top to bottom;
the purification method comprises the following steps: adding pretreated lithium carbonate into a screw pulverizer 2 through a hopper 1, pulverizing the lithium carbonate by the screw pulverizer to improve the dissolution efficiency and save the reaction time, then adding lithium carbonate powder into a reaction kettle 4, adding deionized water into the reaction kettle 4 to prepare suspension, and controlling by using a rotameter 21CO2The flow rate is that the lithium carbonate enters into the lithium carbonate suspension through the air inlet pipe 6, and then the first stirring device 5 starts to stir and heat the water tank 3 for water bath heating to perform reaction; after the reaction is finished, the water pump 8 starts to work, the mixed liquid is pumped into the filter tank 18 through the pipeline 7 and is filtered through the first filter screen 20 and the second filter screen 19, and the purity is improved; then the lithium carbonate suspension is passed through the ion exchange column 17; the treated lithium carbonate suspension flows into the stirring box 9, amino acid crystals are added through the feeding hole 16, and then the lithium carbonate suspension is stirred and mixed through the second stirring device 15 and is heated through the heating sheet 14 arranged inside the stirring box 9; after pyrolysis is completed, opening a control valve 13, enabling the mixed solution to enter a filtering device 10, filtering through a third filter screen 12 and a fourth filter screen 11, recycling the mother solution to obtain a filter cake, namely lithium carbonate crystals, washing the lithium carbonate crystals with deionized water for several times to remove impurities, and finally drying through a drying device to obtain battery-grade lithium carbonate; the whole preparation process is simple, integrated and high in automation degree, the working efficiency is improved, the time is saved, the purity of the prepared lithium carbonate crystal can reach 99.98%, and the yield can reach 97.6%.
In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.
Claims (1)
1. A method for purifying industrial-grade lithium carbonate to battery-grade lithium carbonate is characterized in that based on a purification device, the purification method comprises the following steps:
1) carbonizing: weighing a certain amount of pretreated lithium carbonate, adding the lithium carbonate into a screw rod crusher through a funnel, crushing the lithium carbonate through a screw rod, then adding the lithium carbonate into a reaction kettle, adding deionized water into the reaction kettle to prepare suspension with the solid-to-liquid ratio of 20-30:1, and controlling CO by using a rotameter2Flow rate of CO2Entering the lithium carbonate suspension liquid through an air inlet pipe at the flow rate of 0.8-1.2L/min, and then starting stirring by a first stirring device and heating a water tank for water bath heating;
2) and (3) filtering: after the reaction is finished, the water pump starts to work, the mixed liquid is pumped into the filter box through the pipeline and is filtered through the first filter screen and the second filter screen;
3) ion exchange refining: mixing 748 resin solution and modified D751 chelating resin according to a ratio of 1:1, filling the mixture into an ion exchange column, and then enabling lithium carbonate suspension to flow through the ion exchange column at a flow rate of 0.04-0.07L/min;
4) and (3) pyrolysis reaction: the lithium carbonate suspension treated in the step 3) flows into a stirring box, amino acid crystals are added through a feeding hole, then the lithium carbonate suspension is stirred and mixed through a second stirring device, and is heated through a heating sheet arranged inside the stirring box to perform pyrolysis reaction;
5) drying treatment: after pyrolysis is completed, opening a control valve, enabling the mixed solution to enter a filtering device, filtering through a third filter screen and a fourth filter screen, recycling the mother solution, enabling the filter cake to be lithium carbonate crystals, washing the lithium carbonate crystals with deionized water for 2-5 times, removing impurities, and finally drying through a drying device to obtain battery-grade lithium carbonate;
the preparation method of the pretreated lithium carbonate comprises the following steps:
s1, preparing a lithium chloride solution with the concentration of 3.2mol/L and a sodium carbonate solution with the concentration of 2.8mol/L, filtering through a filter screen, respectively, adding the filtered lithium chloride solution into a reaction kettle of a full-automatic synthesis workstation, adding a 110% sodium carbonate solution into the reaction kettle according to the flow of 0.8-1L/min, and heating and stirring;
s2, after the charging is finished, continuously keeping the original heating temperature and stirring speed, continuously reacting for 30min, then taking out the obtained suspension, filtering through a filter screen in a suction filtration mode, wherein filter residues are lithium carbonate crystals, washing with deionized water for 2-5 times, and drying in a drying box to obtain pretreated lithium carbonate;
the stirring speed is 550-650rpm, and the heating temperature is 75-85 ℃;
the sodium carbonate solution is added into the reaction kettle in a reverse feeding mode;
the preparation of the modified D751 chelating resin comprises the following steps:
a1, connecting a fluorine gas cylinder and a nitrogen gas cylinder with the bottom of a glass exchange column through a pipeline, installing a flowmeter on the pipeline, and then connecting the top of the glass exchange column with two buffer bottles through another pipeline; firstly opening a nitrogen valve, replacing for 20 minutes by nitrogen, checking the tightness of each interface, then drying the D751 chelating resin at 80 ℃ until the water content is less than 10%, filling the dried D751 chelating resin into a glass exchange column with the height of 400mm, respectively adding 300mL of 1mol/L sodium hydroxide into 2 buffer bottles, installing rubber plugs, opening the nitrogen valve, replacing for 15 minutes by nitrogen, checking the air tightness, closing the nitrogen valve, carefully opening the valve of a fluorine gas bottle, slowly adjusting the flow of fluorine gas, starting timing, when a flowmeter shows zero, fully opening the valve of the fluorine gas bottle, keeping for 35 minutes, then opening the nitrogen valve, replacing for 20 minutes, and taking out the D751 chelating resin for later use;
a2, soaking the fluorinated D751 chelate tree in deionized water for 24 hours, and drying by spinning to obtain modified D751 chelate resin;
the heating temperature of the water bath is 15-25 ℃, and the stirring speed of the first stirring device is 350-450 rpm;
the heating temperature of the heating sheet is 60-80 ℃, the stirring speed of the second stirring device is 450-550rpm, and the pyrolysis time is 4-6 hours;
the purification device comprises a funnel, a screw rod crusher, a heating water tank, a reaction kettle, a first stirring device, an air inlet pipe, a pipeline, a water pump, a stirring box, a filtering device, a fourth filtering net, a third filtering net, a control valve, a heating sheet, a second stirring device, a feeding port, an ion exchange column, a filtering box, a second filtering net, a first filtering net and a rotor flow meter, wherein one end of the top of the screw rod crusher is fixedly connected with the funnel, a discharging port at one side of the screw rod crusher is connected with a feeding port arranged on the reaction kettle, one end of the top of the reaction kettle is connected with the rotor flow meter through the air inlet pipe, the rotor flow meter controls the flow of carbon dioxide, the first stirring device is arranged inside the reaction kettle for stirring, the heating water tank is arranged at the bottom of the reaction kettle for water bath heating, the pipeline arranged inside the reaction kettle extends out of the reaction kettle, and, the inside of rose box has set gradually first filter screen and second filter screen and has filtered, and the mesh number of first filter screen is the twice of second filter screen, and the filter effect is good, and the purity is improved, the bottom and the agitator tank fixed connection of ion exchange column, the feed inlet has been seted up at the top of agitator tank, the inside of agitator tank is provided with second agitating unit, the equal fixedly connected with heating plate in inner wall both sides of agitator tank, the bottom opening and the rose box of agitator tank are connected, and the junction of agitator tank and rose box is provided with control flap, be convenient for open, the convenient row material, the rose box has set gradually third filter screen and fourth filter screen from top to bottom.
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