CN112342407B - Back extraction method of lithium extraction liquid - Google Patents

Back extraction method of lithium extraction liquid Download PDF

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CN112342407B
CN112342407B CN202010750958.8A CN202010750958A CN112342407B CN 112342407 B CN112342407 B CN 112342407B CN 202010750958 A CN202010750958 A CN 202010750958A CN 112342407 B CN112342407 B CN 112342407B
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lithium
stripping
extraction
carbon dioxide
extraction liquid
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CN112342407A (en
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应思斌
刘震
阿锡他
邵卫平
吴建仲
朱玉成
王昶
严新华
王晓明
王俊
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ZHEJIANG XINHUA CHEMICAL CO Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/10—Obtaining alkali metals
    • C22B26/12—Obtaining lithium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
    • C01D15/00—Lithium compounds
    • C01D15/08—Carbonates; Bicarbonates
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/20—Treatment or purification of solutions, e.g. obtained by leaching
    • C22B3/26—Treatment or purification of solutions, e.g. obtained by leaching by liquid-liquid extraction using organic compounds
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
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Abstract

The invention relates to a back extraction method of lithium extraction liquid, which comprises the following steps: (1) Providing a lithium extraction liquid, mixing the lithium extraction liquid with a stripping liquid, and performing stripping to obtain a stripping raffinate containing lithium bicarbonate, wherein the pH value of the stripping raffinate is 7-11, and the pH value of the stripping raffinate is less than or equal to that of the lithium extraction liquid; (2) And heating the strip raffinate, and separating to obtain lithium carbonate. The method can effectively relieve and avoid the acid corrosion of equipment, has high safety, and the lithium carbonate obtained by the method has high purity and low cost.

Description

Back extraction method of lithium extraction liquid
Technical Field
The invention relates to the technical field of lithium extraction, in particular to a back extraction method of lithium extraction liquid.
Background
At present, a solvent extraction method is taken as a very popular lithium extraction new technology at home and abroad, and the purpose of extracting lithium is achieved by utilizing the special extraction performance of an organic solvent on lithium. However, the conventional solvent extraction method still has the following problems: (1) Strong acidic solutions such as hydrochloric acid and sulfuric acid are mainly used for back extraction, so that the production cost is high; (2) The strong acid solution used in the back extraction causes the acidity during the back extraction to be too high, the equipment of metal materials such as stainless steel and the like is seriously corroded, potential safety hazards exist, and the equipment cost is high.
Disclosure of Invention
In view of the above, there is a need to provide a method for stripping lithium extraction solution, which can effectively alleviate and avoid acid corrosion of equipment, has high safety, and can obtain lithium carbonate with high purity and low cost.
A back extraction method of lithium extraction liquid comprises the following steps:
(1) Providing a lithium extraction liquid, mixing the lithium extraction liquid with a stripping liquid, and performing stripping to obtain a stripping raffinate containing lithium bicarbonate, wherein the pH value of the stripping raffinate is 7-11, and the pH value of the stripping raffinate is less than or equal to that of the lithium extraction liquid;
(2) And heating the strip raffinate, and separating to obtain lithium carbonate.
<xnotran> , (1) , , ,1,1,1- -5,5- -2,4- ,1,1,1,2,2- -6,6 -3,5- ,1,1,1,2,2,3,3- -7,7- -4,6- , , , , , ,1- -2- , , ,2- , 14- -4 , , , ,1,10- , N </xnotran> 263 At least one of dimethylbis (N-octadecyl) ammonium chloride, methyldioctylsulfonium chloride and 1-hydroxyethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide.
In one embodiment, the volume ratio of the stripping solution to the lithium extraction solution in step (1) is 1.
In one embodiment, the stripping times in step (1) are greater than or equal to 1, and the time of each stripping is 1-10 minutes.
In one embodiment, the stripping solution in step (1) is a solution of carbon dioxide and water.
In one embodiment, the carbon dioxide is introduced into the water to form the strip liquor, wherein the pressure of the carbon dioxide introduction is less than or equal to 2MPa, and the temperature is 0-40 ℃.
In one embodiment, the pressure at which the carbon dioxide is introduced is 1MPa or less.
In one embodiment, carbon dioxide is also obtained after heating in step (2), and the carbon dioxide is recycled into the water.
In one embodiment, the temperature of the heating in step (2) is 50 ℃ or higher.
In one embodiment, lithium precipitation mother liquor remaining after the lithium carbonate is separated in the step (2) is recycled to the step (1) and mixed with the strip raffinate.
The back extraction method of the lithium extraction liquid has the following beneficial effects:
(1) The lithium extraction liquid is alkaline, and the back extraction raffinate obtained after back extraction is neutral or alkaline, so that a strong acid environment cannot appear in the back extraction process, so that the acidic corrosion to equipment made of metal materials such as stainless steel can be effectively relieved or avoided, the safety is high, and the maintenance cost is low.
(2) The lithium bicarbonate obtained by the back extraction of the invention has the solubility which is reduced along with the rise of the temperature, so the heated lithium bicarbonate is crystallized and precipitated from the back extraction raffinate and is decomposed into lithium carbonate by heating, thus the purity is high, the operation is simple, the production cost is low, and the lithium bicarbonate has no corrosion to equipment and no pollution to the environment.
(3) In the invention, carbon dioxide and the lithium precipitation mother liquor remaining after the lithium carbonate is separated can be recycled, so that the production cost is greatly reduced, three wastes are not generated, and the environmental pollution is avoided.
Drawings
FIG. 1 is a process flow chart of the stripping method of lithium extraction liquid of the present invention.
Detailed Description
The back extraction method of the lithium extraction liquid provided by the invention will be further explained with reference to the attached drawings.
As shown in fig. 1, the method for stripping lithium extraction liquid provided by the present invention comprises:
(1) Providing a lithium extraction liquid, mixing the lithium extraction liquid with a strip liquor, and carrying out strip extraction to obtain a strip raffinate containing lithium bicarbonate, wherein the pH value of the strip raffinate is 7-11, and the pH value of the strip raffinate is less than or equal to that of the lithium extraction liquid;
(2) And heating the strip raffinate, and separating to obtain lithium carbonate.
In the step (1), the lithium extraction liquid is obtained by extracting any extraction liquid, and the extraction liquid comprises alcohol extraction liquid, ketone extraction liquid, quaternary ammonium salt-azo ion chelate-association extraction liquid, crown ether extraction liquid, phthalocyanine extraction liquid and the like.
Preferably, the lithium extraction liquid is obtained by extracting an extraction liquid comprising an extraction agent and a diluent, wherein the volume ratio of the extraction agent to the diluent is not limited, and is adjusted according to the selection of the extraction agent and the diluent, and is preferably 40-50.
<xnotran> , , , , ,1,1,1- -5,5- -2,4- ,1,1,1,2,2- -6,6 -3,5- ,1,1,1,2,2,3,3- -7,7- -4,6- , , , , , ,1- -2- , , ,2- , 14- -4 , , , ,1,10- , N </xnotran> 263 Dimethyl di (N-octadecyl) ammonium chloride, methyldioctylsulfonium chloride, 1-hydroxyethyl-3-methylimidazoleAt least one kind of oxazole bis (trifluoromethylsulfonyl) imide.
Further, the extractant includes at least one hydrophobic liquid capable of forming a chelating structure with lithium, such as alcohol, ketone, etc., in consideration of the fact that the chelating structure formed by the extractant and lithium is more favorable for back extraction.
Taking the formation of a chelate structure as an example, the formula of the extractant of the present invention in extracting lithium can be expressed as follows:
(1)Li + +S→S→Li + ；
wherein S represents an extractant, S → Li + Indicating the chelating structure formed by the extractant and lithium.
Specifically, the diluent is selected from at least one of n-hexane, n-dodecane, cyclohexane, D70 special solvent naphtha, D80 special solvent naphtha, no. 120 solvent naphtha, no. 160 solvent naphtha, no. 200 solvent naphtha, common kerosene, aviation kerosene and sulfonated kerosene.
After extraction is finished, lithium extraction liquid and lithium extraction raffinate (namely water phase) incompatible with the lithium extraction liquid can be obtained through separation, and the method is simple.
And after the lithium extraction liquid is obtained by separation, mixing the lithium extraction liquid with the stripping liquid, and performing stripping to obtain a stripping raffinate containing lithium bicarbonate.
The stripping solution is preferably carbonic acid in order to obtain lithium bicarbonate.
The stripping solution is preferably a carbonic acid solution in order to obtain lithium bicarbonate.
Furthermore, considering that the carbon dioxide has wide sources and low cost, the carbon dioxide gas can be directly used, or the carbon dioxide is decomposed and prepared from the salt containing the bicarbonate, or the carbon dioxide is prepared by taking the carbonate as the raw material. Therefore, the carbon dioxide is preferably introduced into the water to form the carbonic acid solution as the stripping solution, so that the direct use of the acid solution can be avoided, the purchase, transportation and storage costs of raw materials are reduced, and the operation safety is improved.
Specifically, the carbon dioxide may be introduced into water and mixed to form a strip liquor, and then the strip liquor and the loaded extract liquor are introduced into strip equipment and mixed, or the carbon dioxide, the water and the loaded extract liquor are introduced into the strip equipment and mixed together to form a strip liquor of the carbon dioxide and the water in the strip equipment. Considering that the stripping solution formed by mixing carbon dioxide and water is carbonic acid, and the carbonic acid also has certain acidity, the carbon dioxide, the water and the loaded extract are preferably introduced into the stripping equipment together to be mixed for stripping, so that not only can the acidic corrosion of the carbonic acid be avoided, but also the operation is simpler.
It is understood that whether carbon dioxide is first introduced into water to mix and form the strip liquor, or carbon dioxide, water and the loaded extract are directly and jointly mixed to carry out strip, the process of introducing carbon dioxide into water to form the strip liquor is included. Whereas under fixed conditions the solubility of carbon dioxide in water is fixed, conditions that affect the solubility of carbon dioxide include primarily pressure and temperature. Therefore, in the present invention, when the carbon dioxide is introduced into the water to form the stripping solution, the pressure at which the carbon dioxide is introduced is preferably 2MPa or less, and the temperature is preferably 0 to 40 ℃.
The pH of the stripping solution formed by introducing carbon dioxide is different under different temperatures and pressures, for example, the pH of the stripping solution formed by introducing carbon dioxide into water is about 5.6 and is weakly acidic under ambient temperature and pressure, and in order to improve the stripping effect, the pressure during introducing carbon dioxide can be properly increased to improve the solubility of carbon dioxide in water, so that the acidity of the formed stripping solution is improved. However, when the pressure is too high, the equipment cost is too high, and potential safety hazards are caused; and, too high an acidity of the strip liquor affects the pH of the strip liquor and can cause corrosion to equipment. Therefore, the pressure at the time of introducing the carbon dioxide is more preferably 1MPa or less, and still more preferably 0.1MPa to 0.5MPa. The pH value of the stripping solution is controlled by controlling the solubility of the carbon dioxide, so that the stripping effect of the stripping solution can be ensured, and the pH value in the stripping process is maintained at about 7, preferably 6-8.
Specifically, the pH of the obtained strip liquor is closer to neutral when the pH in the stripping process is close to 6, and the pH of the obtained strip liquor is closer to 11 when the pH in the stripping process is close to 8.
Meanwhile, in the back extraction process, the pH value is 6-8, so that the problem of equipment corrosion caused by over-strong acidity when strong acids such as hydrochloric acid, sulfuric acid and the like are used can be effectively solved, the safety performance is improved, and the maintenance and updating cost of the equipment is reduced.
It is understood that the water is preferably pure water in order to avoid introducing other trace impurities during stripping to affect the purity of lithium.
Taking carbon dioxide, water and the loaded extract as an example, the equation can be expressed as follows:
(2)S→Li + +CO 2 +H 2 O→S→H + +LiHCO 3 。
similarly, in order to fully strip lithium ions from the loaded extraction liquid to form lithium bicarbonate, the volume ratio of the stripping liquid to the loaded extraction liquid is 1. It can be understood that when the stripping solution is directly used as the carbonic acid solution, the volume ratio of the stripping solution to the loaded extraction solution is the volume ratio of the carbonic acid solution to the loaded extraction solution; when carbon dioxide is mixed with water to form the stripping solution, the volume ratio of the stripping solution to the loaded extraction solution is the volume ratio of the water to the loaded extraction solution.
Specifically, the back extraction frequency is greater than or equal to 1, and the time of each back extraction is 1 to 10 minutes, preferably 5 to 10 minutes.
After the back extraction is finished, the back extraction solution containing the lithium bicarbonate and the idle extraction liquid S → H incompatible with the back extraction solution can be obtained by separation + The empty extract S → H + Can be recycled.
Since the solubility of lithium bicarbonate decreases with increasing temperature, after the stripping solution containing lithium bicarbonate is heated in step (2), lithium bicarbonate is crystallized out of the stripping solution and is decomposed into lithium carbonate by heating, and the reaction equation is as follows:
(3)2LiHCO 3 →Li 2 CO 3 ↓+CO 2 ↑+H 2 O。
in the process, the lithium carbonate is directly obtained by decomposing the lithium bicarbonate, so the obtained lithium carbonate is high-purity lithium carbonate, and the purity can reach 98.5 percent or more.
In addition, impurities such as sodium ions doped in the lithium extraction liquid during the extraction process form impurities such as sodium bicarbonate after back extraction, and the solubility of the impurities such as sodium bicarbonate is increased along with the increase of the temperature, so the impurities such as sodium bicarbonate cannot be crystallized and precipitated to influence the purity of the lithium carbonate.
Specifically, the heating temperature is 50 ℃ or higher, and in view of efficiency and yield, the heating temperature is preferably 70 ℃ to 100 ℃ so that lithium bicarbonate can be sufficiently crystallized and precipitated to be decomposed to form lithium carbonate.
In addition, carbon dioxide can be generated in the process of decomposing the lithium bicarbonate into lithium carbonate, the carbon dioxide can be directly and circularly introduced into water to form a back extraction solution again, no waste gas is generated, and the method is green and environment-friendly.
Similarly, after the lithium carbonate is precipitated, filtered and separated, the remaining lithium precipitation mother liquor can be recycled to the step (1) to be mixed with the stripping solution containing the lithium bicarbonate obtained by the stripping, and the lithium carbonate is concentrated, heated again and crystallized to separate out the lithium carbonate. Of course, the lithium precipitation mother liquor can be collected and then extracted and back extracted separately to prepare lithium carbonate.
Therefore, the back extraction method of the lithium extraction liquid provided by the invention can effectively relieve or avoid the acid corrosion of equipment, has high safety, and simultaneously, the obtained lithium carbonate has high purity, low cost, no waste liquid, and environmental protection.
Hereinafter, the back extraction method of the lithium extraction liquid will be further described by the following specific examples.
Example 1:
respectively taking 20mL of benzoyl trifluoroacetone, 20mL of tris (2-ethylhexyl) phosphate and 60mL of kerosene to uniformly mix in a separating funnel to obtain extract liquor, then adding 300mL of alkaline salt lake brine containing 0.26g/L of lithium, shaking for extraction for 5 minutes without adjusting the pH value of the brine, separating out a water phase and a load extract liquor, extracting for three times, and combining the load extract liquor. Wherein the pH of the loaded extract is 9.
And mixing carbon dioxide and pure water with the loaded extraction liquid, and performing back extraction for three times, wherein the time of single back extraction is 5 minutes, the temperature when the carbon dioxide is introduced is 25 ℃, the pressure is 0.1MPa, and the volume ratio of the back extraction liquid to the loaded extraction liquid is 1. Collecting the water phase to obtain a stripping raffinate containing lithium bicarbonate, wherein the pH value of the stripping raffinate is 9, and the unloaded extract is circulated to the extraction stage for continuous use.
The aqueous solution of lithium bicarbonate collected above was heated to 90 ℃ and filtered to obtain lithium carbonate with a purity of 98.5%. Wherein, the decomposed carbon dioxide is circulated to the back extraction stage, and is filled with pure water to be mixed to form back extraction liquid. And circulating the filtered lithium precipitation mother liquor to a back extraction stage to be mixed with the aqueous solution containing the lithium bicarbonate obtained by the back extraction.
The lithium ion content of each stage is determined by adopting ICP-OES analysis, and the lithium ion content is obtained by analysis and calculation, wherein the primary extraction rate of lithium in the salt lake brine is 50.3%, the secondary extraction rate is 76.5%, the tertiary extraction rate is 88.34%, the primary back-extraction rate is 95.37%, the secondary back-extraction rate is 98.38%, the tertiary back-extraction rate is 99.96%, and the total recovery rate of lithium can reach 86.83%.
Example 2:
the method comprises the steps of firstly, respectively taking 5mL of benzoyl trifluoroacetone, 5mL of trihexyl phosphate and 15mL of kerosene, uniformly mixing in a separating funnel to obtain extract liquor, then adding 100mL of alkaline salt lake brine containing 2.2g/L of lithium, adjusting the pH value of the brine to 11, carrying out oscillation extraction for 10 minutes, separating out a water phase and a load extract liquor, carrying out extraction for three times, and combining the load extract liquor. Wherein the pH of the loaded extract is 11.
And (2) mixing carbon dioxide and pure water with the loaded extraction liquid, and performing back extraction for three times, wherein the time of single back extraction is 5 minutes, the temperature when the carbon dioxide is introduced is 20 ℃, the pressure is 0.15MPa, and the volume ratio of the back extraction liquid to the loaded extraction liquid is 1. Collecting the water phase to obtain the stripping raffinate containing lithium bicarbonate, wherein the pH value of the stripping raffinate is 10, and the unloaded extraction liquid is circulated to the extraction stage for continuous use.
The aqueous solution of lithium hydrogencarbonate collected as above was heated to 85 ℃ and filtered to obtain lithium carbonate having a purity of 98.8%. Wherein, the decomposed carbon dioxide is circulated to the back extraction stage, and is filled with pure water to be mixed to form back extraction liquid. And circulating the filtered lithium precipitation mother liquor to a back extraction stage to be mixed with the aqueous solution containing the lithium bicarbonate obtained by the back extraction.
The lithium ion content of each stage is determined by adopting ICP-OES analysis, and the lithium ion content is obtained by analysis and calculation, wherein the primary extraction rate of lithium in the salt lake brine is 85.71%, the secondary extraction rate is 98.80%, the tertiary extraction rate is 99.57%, the primary back-extraction rate is 88.61%, the secondary back-extraction rate is 98.25%, the tertiary back-extraction rate is 99.96%, and the total recovery rate of lithium can reach 99.53%.
Example 3:
respectively taking 75mL of benzoyl trifluorodecanone, 75mL of tripentyl phosphate and 200mL of kerosene, uniformly mixing in a separating funnel to obtain an extract, adding 700mL of alkaline salt lake brine containing 1.5g/L of lithium, adjusting the pH value of the brine without adjusting, oscillating for 10 minutes, separating out a water phase and a load extract, extracting for three times, and combining the load extract. Wherein the pH of the loaded extract is 10.
And mixing carbon dioxide and pure water with the loaded extraction liquid, and performing back extraction for three times, wherein the time of single back extraction is 6 minutes, the temperature when the carbon dioxide is introduced is 30 ℃, the pressure is 0.2MPa, and the volume ratio of the back extraction liquid to the loaded extraction liquid is 1. Collecting the water phase to obtain a stripping raffinate containing lithium bicarbonate, wherein the pH value of the stripping raffinate is 10, and the unloaded extract is circulated to the extraction stage for continuous use.
The aqueous solution of lithium hydrogencarbonate collected as above was heated to 92 ℃ and filtered to obtain lithium carbonate having a purity of 99%. Wherein, the decomposed carbon dioxide is circulated to the back extraction stage, and is filled with pure water to be mixed to form back extraction liquid. And circulating the filtered lithium precipitation mother liquor to a back extraction stage to be mixed with the aqueous solution containing the lithium bicarbonate obtained by the back extraction.
The lithium ion content of each stage is determined by adopting ICP-OES analysis, and the lithium ion content is obtained by analysis and calculation, wherein the primary extraction rate of lithium in the salt lake brine is 80.81%, the secondary extraction rate is 97.39%, the tertiary extraction rate is 99.59%, the primary back-extraction rate is 83.85%, the secondary back-extraction rate is 98.20%, the tertiary back-extraction rate is 99.93%, and the total recovery rate of lithium can reach 99.52%.
Example 4:
the method comprises the steps of firstly, respectively and uniformly mixing 20mL of benzoyl trifluorodecanone, 20mL of tri (2-ethylhexyl) phosphate and 20mL of kerosene in a separating funnel to obtain extract, then adding 60mL of alkaline salt lake brine containing 0.5g/L of lithium, shaking for extraction for 10 minutes without adjusting the pH value of the brine, separating out a water phase and a load extract, extracting for three times, and combining the load extracts. Wherein the pH of the loaded extract is 10.
And (2) mixing carbon dioxide and pure water with the loaded extraction liquid, and performing back extraction for three times, wherein the time of single back extraction is 6 minutes, the temperature when the carbon dioxide is introduced is 40 ℃, the pressure is 0.3MPa, and the volume ratio of the back extraction liquid to the loaded extraction liquid is 1. Collecting the water phase to obtain the stripping raffinate containing lithium bicarbonate, wherein the pH value of the stripping raffinate is 10, and the unloaded extraction liquid is circulated to the extraction stage for continuous use.
The aqueous solution of lithium hydrogencarbonate collected as above was heated to 95 ℃ and filtered to obtain lithium carbonate having a purity of 99%. Wherein the decomposed carbon dioxide is circulated to the back extraction stage, and pure water is filled in the carbon dioxide to be mixed to form back extraction liquid. And circulating the filtered lithium precipitation mother liquor to a back extraction stage to be mixed with the aqueous solution containing the lithium bicarbonate obtained by the back extraction.
The lithium ion content of each stage is determined by adopting ICP-OES analysis, and the lithium ion content is obtained by analysis and calculation, wherein the primary extraction rate of lithium in the salt lake brine is 75.52%, the secondary extraction rate is 86.48%, the tertiary extraction rate is 95.53%, the primary back-extraction rate is 80.74%, the secondary back-extraction rate is 94.06%, the tertiary back-extraction rate is 99.80%, and the total recovery rate of lithium can reach 95.34%.
Example 5:
respectively taking 25mL of benzoyl trifluoroacetone, 25mL of tri (2-ethylhexyl) phosphate and 70mL of kerosene to uniformly mix in a separating funnel to obtain extract liquor, adding 320mL of lithium-containing solution which is 0.22g/L of lithium and remains after preparing lithium carbonate, oscillating and extracting for 5 minutes without adjusting the pH value of brine, separating out a water phase and a load extract liquor, extracting for three times, and combining the load extract liquor. Wherein the pH of the loading extract was 9.
And mixing carbon dioxide and pure water with the loaded extraction liquid, and performing back extraction for three times, wherein the time of single back extraction is 5 minutes, the temperature when the carbon dioxide is introduced is 25 ℃, the pressure is 0.1MPa, and the volume ratio of the back extraction liquid to the loaded extraction liquid is 1. Collecting the water phase to obtain a stripping raffinate containing lithium bicarbonate, wherein the pH value of the stripping raffinate is 9, and the unloaded extract is circulated to the extraction stage for continuous use.
The aqueous solution of lithium bicarbonate collected above was heated to 90 ℃ and filtered to obtain lithium carbonate with a purity of 98.5%. Wherein the decomposed carbon dioxide is circulated to the back extraction stage, and pure water is filled in the carbon dioxide to be mixed to form back extraction liquid. And circulating the filtered lithium precipitation mother liquor to a back extraction stage to be mixed with the aqueous solution containing the lithium bicarbonate obtained by the back extraction.
The lithium ion content of each stage is determined by adopting ICP-OES analysis, and the lithium ion content is obtained by analysis and calculation, wherein the primary extraction rate of lithium in the salt lake brine is 52.1%, the secondary extraction rate is 75.6%, the tertiary extraction rate is 85.23%, the primary back-extraction rate is 94.26%, the secondary back-extraction rate is 97.27%, the tertiary back-extraction rate is 98.85%, and the total recovery rate of lithium can reach 84.25%.
Example 6:
6mL of benzoyl trifluoroacetone, 6mL of trihexyl phosphate and 18mL of kerosene are taken and uniformly mixed in a separating funnel to obtain extraction liquid, 110mL of lithium-containing wastewater generated after recovery of a battery containing 2.1g/L of lithium is added, the pH value is adjusted to 11, an aqueous phase and a load extraction liquid are separated after oscillation extraction is carried out for 10 minutes, extraction is carried out for three times, and the load extraction liquid is combined. Wherein the pH of the loaded extract is 11.
And mixing carbon dioxide and pure water with the loaded extraction liquid, and performing back extraction for three times, wherein the time of single back extraction is 5 minutes, the temperature when the carbon dioxide is introduced is 25 ℃, the pressure is 0.16MPa, and the volume ratio of the back extraction liquid to the loaded extraction liquid is 1. Collecting the water phase to obtain a stripping raffinate containing lithium bicarbonate, wherein the pH value of the stripping raffinate is 10, and the unloaded extract is circulated to the extraction stage for continuous use.
The aqueous solution of lithium bicarbonate collected above was heated to 85 ℃ and filtered to obtain lithium carbonate with a purity of 98.6%. Wherein the decomposed carbon dioxide is circulated to the back extraction stage, and pure water is filled in the carbon dioxide to be mixed to form back extraction liquid. And circulating the filtered lithium precipitation mother liquor to a back extraction stage to be mixed with the aqueous solution containing the lithium bicarbonate obtained by the back extraction.
ICP-OES analysis is adopted to measure the lithium ion content of each stage, and analysis calculation is carried out to obtain the lithium ion extraction rate of the salt lake brine, wherein the primary extraction rate of lithium is 84.60%, the secondary extraction rate is 97.69%, the tertiary extraction rate is 98.45%, the primary back extraction rate is 87.60%, the secondary back extraction rate is 97.14%, the tertiary back extraction rate is 98.85%, and the total recovery rate of lithium can reach 97.31%.
Example 7:
100mL of benzoyl trifluorodecanone, 100mL of tripentyl phosphate and 250mL of kerosene are respectively taken and uniformly mixed in a separating funnel to obtain extract liquor, 800mL of lithium-containing solution remained after 1.43g/L lithium-containing industrial-grade lithium carbonate is added to prepare battery-grade lithium carbonate, the pH value of brine is not required to be adjusted, water phase and load extract liquor are separated after oscillation extraction is carried out for 10 minutes, extraction is carried out for three times, and the load extract liquor is combined. Wherein the pH of the loaded extract is 10.
And (2) mixing carbon dioxide and pure water with the loaded extraction liquid, and performing back extraction for three times, wherein the time of single back extraction is 6 minutes, the temperature when the carbon dioxide is introduced is 30 ℃, the pressure is 0.2MPa, and the volume ratio of the back extraction liquid to the loaded extraction liquid is 1. Collecting the water phase to obtain a stripping raffinate containing lithium bicarbonate, wherein the pH value of the stripping raffinate is 10, and the unloaded extract is circulated to the extraction stage for continuous use.
The aqueous solution of lithium hydrogencarbonate collected as above was heated to 93 ℃ and filtered to obtain lithium carbonate having a purity of 98.9%. Wherein, the decomposed carbon dioxide is circulated to the back extraction stage, and is filled with pure water to be mixed to form back extraction liquid. And circulating the filtered lithium precipitation mother liquor to a back extraction stage to be mixed with the aqueous solution containing the lithium bicarbonate obtained by back extraction.
ICP-OES analysis is adopted to measure the lithium ion content of each stage, and analysis and calculation are carried out to obtain the lithium ion extraction rate-lithium extraction method, wherein the primary extraction rate of lithium in the salt lake brine is 79.80%, the secondary extraction rate is 96.72%, the tertiary extraction rate is 98.48%, the primary back extraction rate is 82.74%, the secondary back extraction rate is 97.19%, the tertiary back extraction rate is 98.82%, and the total recovery rate of lithium can reach 99.31%.
Example 8:
respectively taking 30mL of benzoyltrifluorodecanone, 30mL of tris (2-ethylhexyl) phosphate and 40mL of kerosene to uniformly mix in a separating funnel to obtain extract liquor, then adding 100mL of lithium-containing solution left after preparing lithium carbonate by an ore method with 0.5g/L of lithium, adjusting the pH value of brine without adjusting, oscillating and extracting for 10 minutes, separating out a water phase and a load extract liquor, extracting for three times, and combining the load extract liquor. Wherein the pH of the loaded extract is 10.
And mixing carbon dioxide and pure water with the loaded extraction liquid, performing back extraction for three times, wherein the time of single back extraction is 6 minutes, the temperature when the carbon dioxide is introduced is 40 ℃, the pressure is 0.3MPa, and the volume ratio of the back extraction liquid to the loaded extraction liquid is 1. Collecting the water phase to obtain a stripping raffinate containing lithium bicarbonate, wherein the pH value of the stripping raffinate is 10, and the unloaded extract is circulated to the extraction stage for continuous use.
The aqueous solution of lithium bicarbonate collected above was heated to 94 ℃ and filtered to obtain lithium carbonate with a purity of 99%. Wherein, the decomposed carbon dioxide is circulated to the back extraction stage, and is filled with pure water to be mixed to form back extraction liquid. And circulating the filtered lithium precipitation mother liquor to a back extraction stage to be mixed with the aqueous solution containing the lithium bicarbonate obtained by the back extraction.
The lithium ion content of each stage is determined by adopting ICP-OES analysis, and the lithium ion content is obtained by analysis and calculation, wherein the primary extraction rate of lithium in the salt lake brine is 74.41%, the secondary extraction rate is 85.37%, the tertiary extraction rate is 94.42%, the primary back-extraction rate is 79.80%, the secondary back-extraction rate is 93.05%, the tertiary back-extraction rate is 98.79%, and the total recovery rate of lithium can reach 93.27%.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (9)

1. A method for stripping lithium extraction liquid is characterized by comprising the following steps:
(1) Providing a lithium extraction liquid, mixing the lithium extraction liquid with a stripping liquid, and performing stripping to obtain a stripping raffinate containing lithium bicarbonate, wherein the pH value of the stripping raffinate is 7 to 11, the pH value of the stripping raffinate is less than or equal to that of the lithium extraction liquid, the stripping liquid is a solution formed by carbon dioxide and water, during stripping, the carbon dioxide is firstly introduced into the water to form the stripping liquid, and then the stripping liquid is mixed with the lithium extraction liquid to perform stripping, or the carbon dioxide, the water and the lithium extraction liquid are directly introduced together to perform stripping;
(2) And heating the strip raffinate, and separating to obtain lithium carbonate.
2. <xnotran> 1 , , (1) , , ,1,1,1- -5,5- -2,4- ,1,1,1,2,2- -6,6 -3,5- ,1,1,1,2,2,3,3- -7,7- -4,6- , , , , , ,1- -2- , , ,2- , 14- -4 , , , ,1,10- , N </xnotran> 263 At least one of dimethylbis (N-octadecyl) ammonium chloride, methyldioctylsulfonium chloride and 1-hydroxyethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide.
3. The method for stripping lithium extraction liquid according to claim 1, wherein the volume ratio of the stripping solution to the lithium extraction liquid in step (1) is 1 to 4.
4. The method for stripping lithium extract according to claim 1, wherein the stripping time in step (1) is greater than or equal to 1, and each stripping time is 1-10 minutes.
5. The method for stripping lithium extract according to claim 1, wherein the carbon dioxide is introduced into the water to form the strip liquor, wherein the carbon dioxide is introduced at a pressure of 2MPa or less and at a temperature of 0 ℃ to 40 ℃.
6. The method for stripping a lithium extract according to claim 5, wherein the pressure at which the carbon dioxide is introduced is 1MPa or less.
7. The method for stripping lithium extract according to claim 5, wherein carbon dioxide is also obtained after heating in step (2), and the carbon dioxide is recycled into the water.
8. The method for stripping lithium extract according to claim 1, wherein the temperature of the heating in step (2) is 50 ℃ or higher.
9. The method for stripping lithium extract according to claim 1, wherein the lithium precipitation mother liquor remaining after the separation of lithium carbonate in step (2) is recycled to step (1) and mixed with the strip raffinate.
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