CN114572949A - Production process of lithium dihydrogen phosphate - Google Patents
Production process of lithium dihydrogen phosphate Download PDFInfo
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- CN114572949A CN114572949A CN202210219083.8A CN202210219083A CN114572949A CN 114572949 A CN114572949 A CN 114572949A CN 202210219083 A CN202210219083 A CN 202210219083A CN 114572949 A CN114572949 A CN 114572949A
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- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/30—Alkali metal phosphates
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- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
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- C01B25/308—Methods for converting an alkali metal orthophosphate into another one; Purification; Decolorasing; Dehydrating; Drying
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Abstract
The invention relates to the technical field of production of lithium iron phosphate serving as a new energy battery raw material, and discloses a production process of lithium dihydrogen phosphate. The lithium solvent extraction adopts the technology of the extraction of beta-diketone and neutral phosphorus extractant, and the lithium-containing wastewater can contain no chloride ions. The lithium content in the lithium-containing wastewater can be as low as 0.1g/l, and the lithium concentration of raffinate can be reduced to be below 10 ppm. And (4) performing back extraction on the lithium-loaded organic phase by using a phosphoric acid aqueous solution to obtain a lithium dihydrogen phosphate aqueous solution. And (3) evaporating, concentrating, cooling, crystallizing and carrying out solid-liquid separation on the lithium dihydrogen phosphate aqueous solution to obtain a lithium dihydrogen phosphate crude product. And refining the crude lithium dihydrogen phosphate to obtain the battery-grade lithium dihydrogen phosphate. The method can greatly reduce the production cost of the lithium dihydrogen phosphate, simultaneously reduce the generation of three wastes, and has good economic benefit and social benefit.
Description
Technical Field
The invention relates to the technical field of production of new energy battery raw material lithium iron phosphate, and particularly relates to a production process of lithium dihydrogen phosphate.
Background
The lithium iron phosphate is used as the anode material of the battery, has good safety and low cost, and is widely applied to lithium batteries of new energy automobiles. Lithium dihydrogen phosphate is a raw material for producing lithium iron phosphate, and has a promising market prospect.
At present, the production process of lithium dihydrogen phosphate mainly comprises a lithium carbonate method and a lithium hydroxide monohydrate method. Lithium carbonate and lithium hydroxide need lithium sulfate or lithium chloride as raw materials, and simultaneously need to consume a large amount of sodium carbonate or sodium hydroxide, and the process flow is complicated, so the price of lithium dihydrogen phosphate is always high. In order to reduce the production cost of lithium dihydrogen phosphate and simplify the production process of lithium dihydrogen phosphate, a new method for producing lithium dihydrogen phosphate needs to be developed.
Disclosure of Invention
The invention aims to provide a production process of lithium dihydrogen phosphate, and aims to solve the problems of complex production process and high cost of lithium dihydrogen phosphate in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme: a production process of lithium dihydrogen phosphate comprises the steps of lithium solvent extraction, lithium dihydrogen phosphate aqueous solution concentration and lithium dihydrogen phosphate crystallization and refining, wherein in the lithium solvent extraction process, lithium-containing wastewater is mixed with an organic phase containing a lithium extraction agent, and lithium is extracted into the organic phase to obtain a lithium-carrying organic phase; washing the lithium-carrying organic phase to remove impurities, and performing back extraction by using phosphoric acid to obtain a lithium dihydrogen phosphate aqueous solution; the lithium extracting agent is a mixture of beta-diketone, tributyl phosphate and trioctylphosphine oxide; the chemical structure of the extractant beta-diketone is shown as the formula (I):
in the formula (I), R1, R2 and R3 are F, H or CH3R4 is H orSaturated alkyl of C1-C10.
In the technical scheme, when the production process of the lithium dihydrogen phosphate is researched, the prepared lithium dihydrogen phosphate meets the requirements of the Chinese non-ferrous metal industry standard YS/T967-charge 2014 in the modes of extraction, back extraction and refining. In the process of optimizing the process, the selection of the lithium extractant is crucial, and improper selection of the extractant can cause the extraction rate and the product purity to be not up to the standard. In the process of optimizing the extracting agent, the inventor conducts research and development and optimization on the extracting agent for many times, and once the extracting agent is single beta-diketone, tributyl phosphate and trioctylphosphine oxide, the two extracting agents are compounded for use, but the effect is not good enough. It is found that when the beta-diketone, tributyl phosphate and trioctylphosphine oxide are mixed as the extracting agent, the extraction rate and the product purity can be greatly improved, and the process is simple and is suitable for industrial popularization and application.
Preferably, as a modification, the beta-diketone is a mixture of beta-diketones of different structures of R1, R2, R3 and R4.
In the technical scheme, the beta-diketone with different group structures (mainly different structures of R1, R2, R3 and R4) is mixed and applied, and compared with the beta-diketone with a single structure, the solubility of the extract compound in a diluent is improved, the loading capacity of metal ions is increased, the risk of crystal precipitation in the extraction process is reduced, and the extraction rate is also obviously improved.
Preferably, as an improvement, the mass ratio of the beta-diketone to tributyl phosphate and trioctylphosphine oxide in the lithium extractant is beta-diketone: tributyl phosphate (10: 1-1: 10), beta-diketone: the trioctylphosphine oxide is 10: 1-50: 1, the extractant further comprises C8-C12 saturated carboxylic acid, and the mass ratio of the beta-diketone to the C8-C12 saturated carboxylic acid is 10: 1-1: 10.
In the technical scheme, the lithium extraction requirements of lithium-containing wastewater with different compositions can be met by optimizing the addition ratio of each component in the lithium extraction agent, if the content of calcium and magnesium in the lithium-containing wastewater is low, the lithium extraction effect of beta-diketone can be reduced by adding too much tributyl phosphate, the cost of the extraction agent can be increased by adding too much trioctylphosphine oxide, and the lithium extraction rate can be reduced by adding too much saturated carboxylic acid. In addition, research finds that lithium can be selectively extracted from waste water containing high-concentration magnesium chloride and calcium chloride after the lithium extracting agent is loaded with iron, and the production process is hardly limited by the composition of impurities in the lithium-containing waste water.
Preferably, as an improvement, the concentration of the lithium extracting agent in the organic phase is 1-60% (V/V), the concentration of lithium in the lithium-containing wastewater is 0.1-2 g/L, the extraction process comprises 1-6 stages of extraction, and the extraction phase ratio is 50: 1-1: 10 compared with O/A.
In the technical scheme, the adding concentration of the lithium extracting agent is optimized according to different lithium contents in the wastewater, so that the optimal extraction effect can be achieved. Too low an amount of addition results in insufficient extraction, and too high an amount of addition results in unnecessary waste of extractant. By setting the extraction process to a multi-stage extraction form, the extraction effect can be improved. According to the scheme, the content of lithium in the lithium-containing wastewater can be reduced to 0.1g/l and the concentration of lithium in raffinate can be reduced to below 10ppm by the cooperative optimization of conditions such as extraction process parameters, extraction agent composition and the like, so that the method has very high popularization and application values. In addition, besides lithium, the wastewater treated by the scheme also contains various metal impurities such as potassium, sodium, calcium, magnesium, manganese, iron, cobalt, nickel, copper, zinc, lead and the like, so that the practicability of the process is enhanced.
Preferably, as an improvement, the lithium dihydrogen phosphate aqueous solution is subjected to evaporation concentration, cooling crystallization and liquid-solid separation to obtain a lithium dihydrogen phosphate crude product, and phosphoric acid is supplemented before evaporation concentration to make the concentration of the phosphoric acid reach the concentration of back extraction acid; and mixing the water recovered in the concentration and crystallization process with the crystallization mother liquor for back extraction of lithium.
In the technical scheme, metal ions such as sodium and potassium and anions such as sulfate radical and chloride ion can be removed by washing the lithium-loaded organic phase; then the lithium dihydrogen phosphate aqueous solution is obtained by back extraction, and the crude lithium dihydrogen phosphate product can be obtained by concentration, crystallization and solid-liquid separation, and the process is simple and convenient to operate. The water recovered in the process of concentration and crystallization is mixed with the mother liquor to be used for the back extraction of lithium, so that the cyclic utilization can be realized, and the processing cost is reduced.
Preferably, as an improvement, the washing process is two-stage washing, and each stage is 1-3 stages; the washing liquid of the first-stage washing is 0.01-1mol/L hydrochloric acid or a sodium hydroxide solution with the pH value of 8-10, and the washing phase ratio is 10: 1-1: 10; the washing liquid of the second washing is purified water, and the washing water after washing is combined with the lithium-containing wastewater.
In the technical scheme, the first stage of washing mainly removes alkali metal ions such as sodium and potassium, the second stage of washing mainly removes anions such as sulfate radicals and chloride ions, and because a small amount of lithium ions are contained in washing water after washing, the washing water is combined with lithium-containing wastewater, so that the discharge of lithium can be reduced, and the recovery rate of lithium is improved. The hydrochloric acid concentration and the washing ratio are in a better range verified by tests, and the washing effect can be ensured.
Preferably, as an improvement, the back extraction process is formed by connecting 1-4 stages in series, and 0.1-0.5mol/L phosphoric acid aqueous solution is adopted to back extract lithium to obtain a lithium dihydrogen phosphate aqueous solution; and the stripping phase ratio O/A is 10: 1-1: 10.
According to the technical scheme, after the back extraction is completed each time, the back extraction water phase is supplemented with phosphoric acid to the phosphoric acid concentration required by the back extraction and then used for back extraction again, so that the lithium concentration in the back extraction water phase can be continuously increased, and when the lithium concentration is increased to the preset concentration, the back extraction water phase goes to a concentration device for evaporation and concentration.
Preferably, as an improvement, after the back extraction of lithium is completed, the organic phase is washed with acid to remove metal impurities in the organic phase to obtain a regenerated organic phase, and the regenerated organic phase is returned to the extraction equipment for recycling.
In the technical scheme, after the back extraction of lithium is finished, a plurality of divalent metal ions still remain in the organic phase, and the divalent metal ions are mixed with the organic phase in washing equipment by hydrochloric acid aqueous solution and separated from washing water to remove the residual metal ions in the organic phase, so that the organic phase is regenerated and reused.
Preferably, as an improvement, the refining process of lithium dihydrogen phosphate is to refine and dry a crude lithium dihydrogen phosphate product to obtain a finished lithium dihydrogen phosphate product.
In the technical scheme, the quality of the lithium dihydrogen phosphate can be improved by refining the crude lithium dihydrogen phosphate product, so that the lithium dihydrogen phosphate meets the requirements of the Chinese non-ferrous metal industry standard YS/T967-2014.
In conclusion, the beneficial effects of the technical scheme are as follows:
1. the production process of the technical scheme is green and environment-friendly, hardly increases the generation of three wastes, and can extract lithium from waste water without chloride ions. The production process mainly comprises two material circulations: 1) the organic phase is circulated, and the extracting agent is regenerated in the pickling equipment and returns to the extraction equipment for recycling; 2) and (4) circulating the crystallization mother liquor, and returning the crystallization mother liquor to back extraction equipment for back extraction of lithium, so that lithium and phosphoric acid are hardly lost. These measures of the present scheme reduce the production cost of lithium dihydrogen phosphate.
2. The technical scheme can realize the separation of lithium and most of metal ions, and metal impurities in the wastewater can also contain transition metal ions such as cobalt, nickel, manganese, zinc, iron, copper and the like besides sodium, potassium, calcium, magnesium and lead. Can utilize lithium-containing waste water with high magnesium chloride content and can also utilize lithium-containing waste water produced in the process of lithium battery recovery treatment.
3. The technical scheme can treat the wastewater with low lithium content, thereby preventing the lithium resource from losing along with the wastewater discharge.
4. The technical scheme extracts lithium from the lithium-containing wastewater and produces the lithium dihydrogen phosphate, and has high economic value and social benefit. And the production process simplifies the production flow of the lithium dihydrogen phosphate, is easy to realize industrialization, and the produced lithium dihydrogen phosphate product has stable quality and meets the requirements of the Chinese non-ferrous metal industry standard YS/T967-charge 2014.
Drawings
FIG. 1 is a flow chart of the lithium dihydrogen phosphate production process of the present invention.
FIG. 2 is a flow diagram of the solvent extraction process of example 1.
Figure 3 is a flow diagram of the solvent extraction process of example 2.
Figure 4 is a flow diagram of the solvent extraction process of example 3.
Detailed Description
The following is a detailed description of the embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following embodiments are conventional means well known to those skilled in the art; the experimental methods used are all conventional methods; the materials, reagents and the like used are all commercially available.
Reference numerals in the drawings of the specification include: the method comprises the following steps of lithium solvent extraction 1, lithium dihydrogen phosphate aqueous solution concentration and lithium dihydrogen phosphate crystallization and refining 2, extraction equipment 3, washing equipment 4, stripping equipment 5, evaporation concentration 6, cooling crystallization 7, solid-liquid separation 8, refining 9, drying 10, lithium-containing wastewater 11, raffinate 12, purified water 13, washing water 14, phosphoric acid 15, supersaturated solution 16, mother liquor 17, lithium dihydrogen phosphate crude product 18, organic phase 19, acid washing equipment 20, hydrochloric acid aqueous solution 21 and phosphoric acid aqueous solution 23.
The scheme is summarized as follows:
as shown in fig. 1, a process for producing lithium dihydrogen phosphate comprises the following steps:
step I, lithium solvent extraction 1: mixing lithium-containing wastewater 11 with an organic phase 19 containing a lithium extracting agent in an extraction device 3, and extracting lithium into the organic phase to obtain a lithium-loaded organic phase; the extraction equipment 3 comprises 1-6 levels of extraction, and the extraction ratio is 50: 1-1: 10; and removing impurities from the lithium-loaded organic phase by washing equipment 4, wherein the washing equipment is divided into two sections, each section is divided into 1-3 stages, the washing liquid in the first section is hydrochloric acid, the concentration of the hydrochloric acid is 0.01-1mol/L, the washing ratio is 10: 1-1: 10, and metal ions such as sodium, potassium and the like are mainly removed. The second washing liquid is purified water 13 which mainly removes anions such as sulfate radicals and chloride ions, and washing water 14 after washing is combined with the lithium-containing wastewater 11. The back extraction of lithium is formed by connecting 1-4 stages in series, the back extraction is carried out by using a phosphoric acid aqueous solution 23 in a back extraction device 5 to obtain a lithium dihydrogen phosphate aqueous solution, an organic phase and a hydrochloric acid aqueous solution 21 are mixed in an acid washing device 20, the organic phase is regenerated and then returned to an extraction device 3 for recycling, the concentration of phosphoric acid for the back extraction of lithium is 0.1-0.5mol/L, and the back extraction phase ratio O/A is 10: 1-1: 10. The lithium extracting agent is a mixture of beta-diketone, tributyl phosphate (TBP) and trioctylphosphine oxide; the volume concentration of the lithium extractant in the organic phase is 1-60%; C8-C12 saturated carboxylic acid can be added in the extraction process to improve the extraction effect. The chemical structure of the extractant beta-diketone is shown as the formula (I):
in the formula (I), R1, R2 and R3 are F, H or CH3R4 is H or saturated alkyl of C1-C10, and the beta-diketone is formed by mixing two or more beta-diketones with different structures of R1, R2, R3 and R4.
When the lithium extraction agent is mixed for use, the lithium extraction agent is a mixture of beta-diketone: tributyl phosphate 10:1 to 1:10, beta-diketone: trioctylphosphine oxide 10:1 to 50:1, beta-diketone: C8-C12 saturated carboxylic acid is 10: 1-1: 10.
Step II, lithium dihydrogen phosphate concentration and crystallization: after phosphoric acid is supplemented to the aqueous solution of lithium dihydrogen phosphate, a crude product 18 of lithium dihydrogen phosphate is obtained through evaporation concentration 6, cooling crystallization 7 and liquid-solid separation 8. The concentration of lithium in the lithium dihydrogen phosphate aqueous solution entering the evaporation concentration stage is 10-25 g/L, and water recovered by evaporation concentration and crystallization mother liquor are mixed for back extraction of lithium and are recycled. The temperature of the cooling crystallization stage is 45-90 ℃.
Step III, lithium dihydrogen phosphate refining: and refining 9 and drying 10 the crude lithium dihydrogen phosphate 18 to obtain a finished lithium dihydrogen phosphate product.
Example 1
The extractant in the embodiment comprises the following components: a mixture of beta-diketone, TBP, trioctylphosphine oxide and neodecanoic acid, and the mass ratio of beta-diketone to TBP is 2:1, beta-diketone to trioctylphosphine oxide is 40:1, and beta-diketone to neodecanoic acid is 8: 1. Wherein the beta-diketone is formed by mixing beta-diketone A and beta-diketone B. The mixing mass ratio of A to B is 2 to 1. The beta-diketone A has the structure: r1, R2, R3 ═ F, R4 ═ CH3. The beta-diketone B has the structure: r1, R2 ═ F, R3 ═ H, R4 ═ C5H11。
The lithium-containing wastewater comprises the following components:
TABLE 1
| Composition (I) | Li | Na | K | Ca | Fe | Pb | Mn |
| Content (g/l) | 0.71 | 8.60 | 10.50 | 0.08 | 0.11 | 0.08 | 4.30 |
Referring to fig. 2, a process for producing lithium dihydrogen phosphate includes the following steps:
step I, lithium solvent extraction: taking 15ml of extracting agent, diluting the extracting agent to 100ml by using hydrogenated kerosene, wherein the concentration of the extracting agent in an organic phase is 15% (v/v), the organic phase is firstly saponified by using 2.8ml of 30% (w/w) sodium hydroxide and then mixed with 100ml of lithium-containing wastewater for 3 minutes, and no solid is separated out in the mixing process. The extraction phase ratio O/A is 1:1, the extraction temperature is 20 ℃, the phase separation is completed within 60 seconds, and the pH value of the raffinate is 6.7. The raffinate lithium concentration was 8.9 ppm. The lithium extraction rate was 98.7%. The lithium-loaded organic phase is first mixed with 100ml of hydrochloric acid solution pH1.5 for 3 minutes and then with 100ml of purified water for 3 minutes at 20 ℃. Then back extraction is carried out by 0.2mol/l phosphoric acid aqueous solution, the back extraction temperature is 60 ℃, the back extraction phase ratio O/A is adjusted, and the back extraction equilibrium pH is controlled to be 3.0-3.5. After the back extraction is finished, the organic phase is mixed with 0.5mol/l hydrochloric acid for 5 minutes to remove impurities such as manganese, iron, lead, calcium and the like in the organic phase. The lithium extraction process is shown in figure 2.
Step II, concentrating and crystallizing lithium dihydrogen phosphate aqueous solution: when the concentration of lithium in the stripping solution is enriched to 22g/l, phosphoric acid is supplemented to 0.2mol/l, evaporation concentration is carried out, and then hot filtration is carried out at 60-70 ℃. The filter cake is a lithium dihydrogen phosphate crude product. The filtrate was mixed with distilled water obtained in the concentration process for the next lithium stripping.
Step III, refining the primary lithium dihydrogen phosphate product: washing the filter cake with absolute ethyl alcohol, and drying at 105 ℃ for 4 hours to obtain the battery-grade lithium dihydrogen phosphate.
The lithium dihydrogen phosphate metal impurities are measured by adopting an atomic absorption spectrum, sulfate radicals and chloride ions are measured by adopting an ion chromatography method, the moisture is measured by adopting a thermal weight loss method, and water insoluble substances are measured by adopting a precise filtration method. The analytical results were as follows:
TABLE 2
The quality of the lithium dihydrogen phosphate meets the requirements of the national non-ferrous metal industry standard YS/T967-2014.
The analysis results of other components of the raffinate, except for lithium, were as follows:
TABLE 3
| Composition (I) | Na | K | Ca | Fe | Pb | Mn |
| Content (g/l) | 8.10 | 9.95 | <0.2ppm | <0.1ppm | <0.1ppm | 1.2ppm |
| Extraction ratio (%) | 0.82 | 0.29 | >99.75 | >99.91 | >99.88 | 99.97 |
Example 2
The extractant in the embodiment comprises the following components: a mixture of beta-diketone, TBP, trioctylphosphine oxide and neodecanoic acid, and the mass ratio of beta-diketone to TBP is 2:1, beta-diketone to trioctylphosphine oxide is 40:1, and beta-diketone to neodecanoic acid is 8: 1. Wherein the beta-diketone is formed by mixing beta-diketone A and beta-diketone B. The mixing mass ratio of A to B is 2 to 1. The beta-diketone A has the structure: r1, R2, R3 ═ F, R4 ═ CH3. The beta-diketone B has the structure: r1, R2, R3 ═ F, and R4 ═ H.
The lithium-containing wastewater comprises the following components:
TABLE 4
| Composition (I) | Li | Na | K | Ca | Fe | Pb | Mn |
| Content (g/l) | 0.13 | 12.50 | 17.60 | 0.05 | 0.07 | 0.08 | 9.30 |
Referring to fig. 3, a process for producing lithium dihydrogen phosphate includes the following steps:
step I, solvent extraction of lithium: taking 25ml of extracting agent, diluting the extracting agent to 100ml by using hydrogenated kerosene, wherein the concentration of the extracting agent in an organic phase is 25% (v/v), the organic phase is firstly saponified by using 4.6ml of 30% (w/w) sodium hydroxide, and then is mixed with 100ml of lithium-containing wastewater for 3 minutes, and no solid is separated out in the mixing process. Compared with the extraction ratio of O/A (1: 1), the extraction temperature is 20 ℃, the phase separation is completed within 60 seconds, the pH of raffinate is 6.7, the lithium concentration of raffinate is 11ppm, and the lithium extraction rate is 91.5%. The lithium concentration of raffinate 2 is 6.6ppm, and the lithium extraction rate is 94.8%. The lithium-loaded organic phase is first mixed with 100ml of 0.06mol/l hydrochloric acid for 3 minutes and then with 100ml of purified water for 3 minutes at a temperature of 20 ℃. Then back extraction is carried out by 0.1mol/l phosphoric acid, the back extraction temperature is 50 ℃, the back extraction phase ratio O/A is adjusted, and the back extraction equilibrium pH is controlled to be 3.0-3.5. After the back extraction is finished, the organic phase is mixed with 0.8mol/l hydrochloric acid for 5 minutes to wash out impurities such as calcium, lead, iron, manganese and the like. The lithium extraction process is shown in figure 3.
Step II, concentrating and crystallizing lithium dihydrogen phosphate aqueous solution: when the concentration of lithium in the stripping solution is enriched to 22g/l, phosphoric acid is supplemented to 0.1mol/l, evaporation concentration is carried out, and then hot filtration is carried out at 60-70 ℃. The filter cake is a lithium dihydrogen phosphate crude product. The filtrate is mixed with distilled water obtained in the concentration process and then used for the back extraction of lithium next time.
Step III, refining the primary lithium dihydrogen phosphate product: the filter cake was washed with absolute ethanol and dried at 105 ℃ for 4 hours. Obtaining the battery-grade lithium dihydrogen phosphate.
The lithium dihydrogen phosphate metal impurities are measured by adopting an atomic absorption spectrum, sulfate radicals and chloride ions are measured by adopting an ion chromatography method, the moisture is measured by adopting a thermogravimetric method, and water-insoluble substances are measured by adopting a precise filtration method. The analytical results were as follows:
TABLE 5
The quality of the lithium dihydrogen phosphate meets the requirements of the national non-ferrous metal industry standard YS/T967-2014.
The analysis results of other components of the raffinate, except for lithium, were as follows:
TABLE 6
| Composition (I) | Na | K | Ca | Fe | | Mn |
| Raffinate | ||||||
| 1 content (g/l) | 12.44 | 17.57 | <0.2ppm | <0.1ppm | <0.1ppm | 0.9ppm |
| E1 extraction Rate (%) | 0.48 | 0.17 | >99.60 | >99.86 | >99.88 | 99.99 |
| |
12.14 | 17.19 | <0.2ppm | <0.1ppm | <0.1ppm | 1.9ppm |
| E2 extraction Rate (%) | 1.20 | 0.68 | >99.60 | >99.86 | >99.88 | 99.98 |
Example 3
The lithium extractants of this example were: a mixture of beta-diketone, TBP, trioctylphosphine oxide and neodecanoic acid, and the mass ratio of beta-diketone to TBP is 2:1, beta-diketone to trioctylphosphine oxide is 40:1, and beta-diketone to neodecanoic acid is 8: 1. Wherein the beta-diketone is formed by mixing beta-diketone A and beta-diketone B. The mixing mass ratio of A to B is 1 to 3. The structure of the beta-diketone A is as follows: r1, R2, R3 ═ F, R4 ═ CH3. The beta-diketone B has the structure: r1, R2, R3 ═ CH3，R4＝C5H11。
The lithium-containing wastewater comprises the following components:
TABLE 7
| Composition (I) | Li | Na | K | Ca | Fe | Pb | Mg | Cl- |
| Content (g/l) | 1.52 | 8.60 | 10.50 | 18.8 | 0.11 | 3.82 | 73.3 | 280 |
Referring to fig. 4, a process for producing lithium dihydrogen phosphate includes the following steps:
step I, solvent extraction of lithium: taking 50.0ml of extracting agent, diluting the extracting agent to 100ml by using hydrogenated kerosene, mixing the organic phase with hydrochloric acid solution (containing 20g/l of Fe, 6mol/l of NaCl and 2mol/l of HCl) of ferric trichloride for 3 minutes and then mixing the organic phase with 100ml of lithium-containing wastewater for 3 minutes, wherein the concentration of the extracting agent in the organic phase is 50% (v/v). The extraction phase ratio O/a was 1:1, the extraction temperature was 30 ℃, the raffinate pH was 1.2, and the raffinate lithium concentration was 128 ppm. The lithium extraction rate was 91.6%. The lithium-loaded organic phase was mixed with 100ml of a sodium hydroxide solution having a pH of 9 for 3 minutes and then with 100ml of purified water for 3 minutes at 30 ℃ without precipitation of solids during the mixing, and the phase separation was completed in 60 seconds. Then back extraction is carried out by 0.3mol/l phosphoric acid, the back extraction temperature is 50 ℃, the back extraction phase ratio O/A is adjusted, and the back extraction equilibrium pH is controlled to be 3.0-3.5. After the back extraction was completed, the organic phase was mixed with a hydrochloric acid solution of sodium chloride (3mol/l hydrochloric acid, 5mol/l sodium chloride) for 5 min. The organic phase is reused. The lithium extraction process is shown in figure 4.
Step II, concentrating and crystallizing lithium dihydrogen phosphate aqueous solution: when the concentration of lithium in the stripping solution is enriched to 22g/l, supplementing phosphoric acid to 0.3mol/l, carrying out evaporation concentration, and then filtering while the solution is hot at 60-70 ℃. The filter cake is a lithium dihydrogen phosphate crude product. The filtrate is mixed with distilled water obtained in the concentration process and then used for the back extraction of lithium next time.
Step III, refining the primary lithium dihydrogen phosphate product: the filter cake was washed with absolute ethanol and dried at 105 ℃ for 4 hours. Obtaining the battery-grade lithium dihydrogen phosphate.
The lithium dihydrogen phosphate metal impurities are measured by adopting an atomic absorption spectrum, sulfate radicals and chloride ions are measured by adopting an ion chromatography method, the moisture is measured by adopting a thermal weight loss method, and water insoluble substances are measured by adopting a precise filtration method. The analytical results were as follows:
TABLE 8
The quality of the lithium dihydrogen phosphate meets the requirements of the national non-ferrous metal industry standard YS/T967-2014.
The analysis results of other components of the raffinate, except for lithium, were as follows:
TABLE 9
| Composition (I) | Na | K | Ca | Fe | Pb | Mg |
| Content (g/l) | 8.08 | 9.93 | 17.76 | 0.01 | 3.60 | 69.2 |
| Extraction ratio (%) | 1.16 | 0.48 | 0.56 | 90.43 | 0.78 | 0.62 |
Comparative example 1
The extractant in the embodiment comprises the following components: a mixture of beta-diketone, TBP and trioctylphosphine oxide, and the mass ratio of beta-diketone to TBP is 2:1, and beta-diketone to trioctylphosphine oxide is 70: 1. Wherein the beta-diketone is a beta-diketone with a single structure. R1, R2, R3 ═ F, and R4 ═ H.
The lithium-containing wastewater comprises the following components:
TABLE 10
| Composition (I) | Li | Na | K | Ca | Fe | Pb | Mn |
| Content (g/l) | 0.13 | 12.50 | 17.60 | 0.05 | 0.07 | 0.08 | 9.30 |
A production process of lithium dihydrogen phosphate comprises the following steps:
step I, solvent extraction of lithium: taking 25ml of extracting agent, diluting the extracting agent to 100ml by using hydrogenated kerosene, wherein the concentration of the extracting agent in an organic phase is 25% (v/v), the organic phase is firstly saponified by using 4.6ml of 30% (w/w) sodium hydroxide and then mixed with 100ml of lithium-containing wastewater for 3 minutes, and solids are separated out in the mixing process of E1 to influence phase separation. Compared with the extraction ratio of O/A (1: 1), the extraction temperature is 20 ℃, the phase separation is completed within 60 seconds, the pH of raffinate is 6.7, the lithium concentration of raffinate is 53ppm, and the lithium extraction rate is 59.2%. The lithium concentration of the raffinate 2 is 15ppm, and the lithium extraction rate is 88.5 percent. The lithium-loaded organic phase is first mixed with 100ml of 0.06mol/l hydrochloric acid for 3 minutes and then with 100ml of purified water for 3 minutes at a temperature of 20 ℃. Then back extraction is carried out by 0.5mol/l phosphoric acid, the back extraction temperature is 50 ℃, the back extraction phase ratio O/A is adjusted, and the back extraction equilibrium pH is controlled to be 0.5-1.0. After the back extraction is finished, the organic phase is mixed with 0.8mol/l hydrochloric acid for 5 minutes to wash out impurities such as calcium, lead, iron, manganese and the like. The lithium extraction process is shown in figure 3.
Step II, concentrating and crystallizing lithium dihydrogen phosphate aqueous solution: when the concentration of lithium in the stripping solution is enriched to 22g/l, evaporation concentration is carried out, and then filtration is carried out while the solution is hot at 60-70 ℃. The filter cake is a lithium dihydrogen phosphate crude product. The filtrate is mixed with distilled water obtained in the concentration process and then used for the back extraction of lithium next time.
Step III, refining the primary lithium dihydrogen phosphate product: the filter cake was washed with absolute ethanol and dried at 105 ℃ for 4 hours. Obtaining the battery-grade lithium dihydrogen phosphate.
The lithium dihydrogen phosphate metal impurities are measured by adopting an atomic absorption spectrum, sulfate radicals and chloride ions are measured by adopting an ion chromatography method, the moisture is measured by adopting a thermal weight loss method, and water insoluble substances are measured by adopting a precise filtration method. The analytical results were as follows:
TABLE 11
In addition, the content of water is 2.47 percent and is not listed in the table, so the quality of the lithium dihydrogen phosphate can not meet the requirement of the standard YS/T967-2014 in the non-ferrous metal industry of China.
Comparative example 2
The lithium extractant of this example was: a mixture of beta-diketone, TBP and trioctylphosphine oxide, and the mass ratio of beta-diketone to TBP is 2:1, and beta-diketone to trioctylphosphine oxide is 70: 1. Wherein the beta-diketone is a single-structure beta-diketone. R1, R2, R3 ═ F, R4 ═ CH3。
The lithium-containing wastewater comprises the following components:
TABLE 12
| Composition (I) | Li | Na | K | Ca | Fe | Pb | Mg | Cl- |
| Content (g/l) | 1.52 | 8.60 | 10.50 | 18.8 | 0.11 | 3.82 | 73.3 | 280 |
A production process of lithium dihydrogen phosphate comprises the following steps:
solvent extraction of lithium: taking 50.0ml of extracting agent, diluting the extracting agent to 100ml by using hydrogenated kerosene, mixing the organic phase with hydrochloric acid solution (containing 20g/l of Fe, 6mol/l of NaCl and 2mol/l of HCl) of ferric trichloride for 3 minutes and then mixing the organic phase with 100ml of lithium-containing wastewater for 3 minutes, wherein the concentration of the extracting agent in the organic phase is 50% (v/v). The extraction phase ratio O/a was 1:1, the extraction temperature was 30 ℃, the raffinate pH was 1.2, and the raffinate lithium concentration was 128 ppm. The lithium extraction rate was 91.6%. The lithium-loaded organic phase was mixed with 100ml of a sodium hydroxide solution having a pH of 9 for 3 minutes and then with 100ml of purified water for 3 minutes at a temperature of 30 ℃ to precipitate red solids during the mixing process, resulting in a large loss of iron and extractant, and the experiment was abandoned.
The foregoing is merely an example of the present invention and common general knowledge in the art of designing and/or characterizing particular aspects and/or features is not described in any greater detail herein. It should be noted that, for those skilled in the art, without departing from the technical solution of the present invention, several variations and modifications can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicability of the patent. The scope of the claims of the present application shall be determined by the contents of the claims, and the description of the embodiments and the like in the specification shall be used to explain the contents of the claims.
Claims (9)
1. A production process of lithium dihydrogen phosphate is characterized by comprising the following steps: the method comprises the steps of lithium solvent extraction, lithium dihydrogen phosphate aqueous solution concentration and lithium dihydrogen phosphate crystallization and refining, wherein in the lithium solvent extraction process, lithium-containing wastewater is mixed with an organic phase containing a lithium extraction agent, and lithium is extracted into the organic phase to obtain a lithium-loaded organic phase; washing the lithium-carrying organic phase to remove impurities, and performing back extraction by using phosphoric acid to obtain a lithium dihydrogen phosphate aqueous solution; the lithium extraction agent is a mixture of beta-diketone, tributyl phosphate and trioctylphosphine oxide; the chemical structure of the extractant beta-diketone is shown as the formula (I):
in the formula (I), R1, R2 and R3 are F, H or CH3R4 is H or saturated alkyl of C1-C10.
2. The process for producing lithium dihydrogen phosphate according to claim 1, wherein: the beta-diketone is a mixture formed by combining beta-diketones with different structures of R1, R2, R3 and R4.
3. The process for producing lithium dihydrogen phosphate according to claim 2, wherein: the mass ratio of beta-diketone to tributyl phosphate and trioctylphosphine oxide in the lithium extractant is beta-diketone: tributyl phosphate 10:1 to 1:10, beta-diketone: the trioctylphosphine oxide is 10: 1-50: 1, the extracting agent further comprises C8-C12 saturated carboxylic acid, and the mass ratio of the beta-diketone to the C8-C12 saturated carboxylic acid is 10: 1-1: 10.
4. The process for producing lithium dihydrogen phosphate according to claim 3, wherein: the concentration of the lithium extraction agent in the organic phase is 1-60% (V/V), the concentration of lithium in lithium-containing wastewater is 0.1-2 g/L, the extraction process comprises 1-6 levels of extraction, and the extraction phase ratio is 50: 1-1: 10.
5. The process for producing lithium dihydrogen phosphate according to claim 4, wherein: evaporating and concentrating the lithium dihydrogen phosphate aqueous solution, cooling and crystallizing, and carrying out liquid-solid separation to obtain a lithium dihydrogen phosphate crude product, and supplementing phosphoric acid before evaporating and concentrating to make the concentration of phosphoric acid reach the concentration of back extraction acid; and mixing the water recovered in the concentration and crystallization process with the crystallization mother liquor for back extraction of lithium.
6. The process for producing lithium dihydrogen phosphate according to claim 1, wherein: the washing process is two-stage washing, wherein each stage is 1-3 stages; the washing liquid of the first-stage washing is 0.01-1mol/L hydrochloric acid or a sodium hydroxide solution with the pH value of 8-10, and the washing phase ratio is 10: 1-1: 10; the washing liquid of the second washing is purified water, and the washing water after washing is combined with the lithium-containing wastewater.
7. The process for producing lithium dihydrogen phosphate according to claim 1, wherein: the back extraction process is formed by connecting 1-4 stages in series, and lithium is back extracted by adopting 0.1-0.5mol/L phosphoric acid aqueous solution to obtain lithium dihydrogen phosphate aqueous solution; and the stripping phase ratio O/A is 10: 1-1: 10.
8. The process for producing lithium dihydrogen phosphate according to claim 7, wherein: after the back extraction of the lithium is finished, the organic phase is washed by acid, metal impurities in the organic phase are removed to obtain a regenerated organic phase, and the regenerated organic phase returns to the extraction equipment for recycling.
9. The process for producing lithium dihydrogen phosphate according to claim 8, wherein: the lithium dihydrogen phosphate is refined by refining and drying the crude lithium dihydrogen phosphate product to obtain the finished lithium dihydrogen phosphate product.
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| CN115477355A (en) * | 2022-09-30 | 2022-12-16 | 武汉工程大学 | Method for extracting lithium from lithium-containing wastewater by using TBP (tunnel boring machine) |
| WO2024027447A1 (en) * | 2022-08-01 | 2024-02-08 | 北京索特莱克科技发展有限公司 | New lithium extracting agent and liquid organic mixture thereof, and method for extracting lithium by means of extraction |
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| CN101327919A (en) * | 2007-06-19 | 2008-12-24 | 比亚迪股份有限公司 | Synthetic method of lithium dihydrogen phosphate |
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| CN110656239A (en) * | 2019-11-01 | 2020-01-07 | 中国科学院过程工程研究所 | Method for extracting lithium by extraction-back extraction separation and purification |
| CN111057848A (en) * | 2018-10-16 | 2020-04-24 | 中国科学院过程工程研究所 | Method for extracting lithium from lithium-containing solution by solvent extraction |
| CN112853119A (en) * | 2020-12-30 | 2021-05-28 | 宿迁哈托科技有限公司 | Extraction system for extracting lithium from brine, preparation method of extraction system and method for extracting lithium from brine |
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| CN101327919A (en) * | 2007-06-19 | 2008-12-24 | 比亚迪股份有限公司 | Synthetic method of lithium dihydrogen phosphate |
| KR20180074074A (en) * | 2016-12-23 | 2018-07-03 | 주식회사 포스코 | Manufacturing method of lithium dihydrogen phosphate for battery from dissolved lithium in seawater |
| CN111057848A (en) * | 2018-10-16 | 2020-04-24 | 中国科学院过程工程研究所 | Method for extracting lithium from lithium-containing solution by solvent extraction |
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| WO2024027447A1 (en) * | 2022-08-01 | 2024-02-08 | 北京索特莱克科技发展有限公司 | New lithium extracting agent and liquid organic mixture thereof, and method for extracting lithium by means of extraction |
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