阅读说明：本技术 一种从含锂钠钾铝硫酸盐溶液中选择性萃取回收铝的方法 (Method for selectively extracting and recovering aluminum from lithium sodium potassium aluminum sulfate-containing solution ) 是由 杨声海 李帅 赖延清 陈永明 金胜明 田忠良 莫才宣 于 2021-09-01 设计创作，主要内容包括：本发明属于离子提取技术领域,本发明提供了一种从含锂钠钾铝硫酸盐溶液中选择性萃取回收铝的方法,包含如下步骤：将锂钠钾铝硫酸盐溶液和萃取有机相混合,经过萃取、分层,得到负载有机相和锂钠钾硫酸盐溶液；将负载有机相和反萃液混合,经过反萃、分层,得到有机相和硫酸铝溶液；将硫酸铝溶液顺次经过蒸发、浓缩、冷却结晶,得到Al-(2)(SO-(4))-(3)·18H-(2)O。本发明的方法能够在较广的pH值范围内实现铝离子和锂、钠、钾离子的高效选择性分离,对铝离子具有很高的萃取率和反萃率,得到高纯Al-(2)(SO-(4))-(3)·18H-(2)O；本发明的萃取有机相易于反萃再生,萃取剂无需皂化处理,具有较高的经济效益和环境效益。(The invention belongs to the technical field of ion extraction, and provides a method for selectively extracting and recovering aluminum from a lithium sodium potassium aluminum sulfate solution, which comprises the following steps: mixing the lithium sodium potassium aluminum sulfate solution with the extraction organic phase, and extracting and layering to obtain a loaded organic phase and a lithium sodium potassium sulfate solution; mixing the loaded organic phase and the stripping solution, and performing stripping and layering to obtain an organic phase and an aluminum sulfate solution; the aluminum sulfate solution is evaporated, concentrated, cooled and crystallized in sequence to obtain Al 2 (SO 4 ) 3 ·18H 2 And O. Book (I)The method can realize the high-efficiency selective separation of aluminum ions and lithium, sodium and potassium ions in a wider pH value range, has high extraction rate and back extraction rate on the aluminum ions, and obtains high-purity Al 2 (SO 4 ) 3 ·18H 2 O; the extraction organic phase of the invention is easy to be back extracted and regenerated, the extractant does not need saponification treatment, and the invention has higher economic benefit and environmental benefit.)

1. A method for selectively extracting and recovering aluminum from a lithium sodium potassium aluminum sulfate-containing solution is characterized by comprising the following steps:

1) mixing the lithium sodium potassium aluminum sulfate solution with the extraction organic phase, and extracting and layering to obtain a loaded organic phase and a lithium sodium potassium sulfate solution;

2) mixing the loaded organic phase and the stripping solution, and performing stripping and layering to obtain an organic phase and an aluminum sulfate solution;

3) the aluminum sulfate solution is evaporated, concentrated, cooled and crystallized in sequence to obtain Al₂(SO₄)₃·18H₂O。

2. The method of claim 1, wherein the extracted organic phase in step 1) comprises an extractant, a modifier and a diluent in a volume ratio of 10-40: 2.5-10: 50-87.5.

3. The method of claim 2, wherein the extracting agent comprises one or more of monoalkylphenyl phosphate, dialkylphenyl phosphate and trialkylphenyl phosphate, wherein the alkyl is a straight-chain alkyl and/or branched-chain alkyl, and the straight-chain alkyl and the branched-chain alkyl independently contain 4-18 carbon atoms; the modifier comprises n-butanol and/or isobutanol; the diluent is sulfonated kerosene.

4. The method according to claim 1 or 3, wherein the volume ratio of the lithium sodium potassium aluminum sulfate solution in step 1) to the extracted organic phase is 1-4: 1-4; the extraction temperature is 25-50 ℃, the extraction time is 6-15 min, and the extraction adopts counter-current extraction with 2-8 stages.

5. The method according to claim 4, wherein in the lithium sodium potassium aluminum sulfate solution in the step 1), the concentration of lithium ions is 0.5-15 g/L, the concentration of sodium ions is 5-25 g/L, the concentration of potassium ions is 1.5-15 g/L, and the concentration of aluminum ions is 2-35 g/L; the pH value of the lithium sodium potassium aluminum sulfate solution is 2-5.

6. The method of claim 5, wherein prior to said mixing of step 2), said loaded organic phase is counter-currently washed with water; the volume ratio of the loaded organic phase to water is 1-5: 1; the temperature of the countercurrent washing is 25-50 ℃, and the number of stages is 1-3.

7. The method according to claim 5 or 6, wherein the strip liquor in step 2) is a sulfuric acid solution with acidity of 20-300 g/L; the volume ratio of the loaded organic phase to the stripping solution is 1-10: 1-3.

8. The method according to claim 7, wherein the temperature of the back extraction in the step 2) is 25-50 ℃, the time is 6-15 min, and the back extraction adopts counter-current back extraction with 1-5 stages.

Technical Field

The invention relates to the technical field of ion extraction, in particular to a method for selectively extracting and recovering aluminum from a lithium sodium potassium aluminum sulfate solution.

Background

The solvent extraction method is an efficient technology for extracting and separating aluminum from a lithium-containing sodium-potassium-aluminum sulfate solution, and has the advantages of simple process and equipment, continuous operation, easy realization of automatic control and the like.

The acidic phosphorus (phosphine) extractant generates cation exchange reaction with hydrogen ions in the extractant mainly through metal elements in the extraction process, so that the hydrogen ions in the aqueous solution are continuously enriched, and the water phase equilibrium acidity is influenced. When the extraction reaction is carried out, the distribution ratio of the metal extraction is greatly influenced by the acidity of the water phase. The influence of hydrogen ions released in the process of extracting and separating the metal elements on the process of extracting and separating the metal elements is obvious, the distribution ratio is reduced by 1000 times when the pH value in the aqueous solution is reduced by 1 unit, namely the amount of the metal entering an organic phase through extraction is greatly reduced.

In order to avoid the increase of the concentration of hydrogen ions in aqueous solution in the extraction process, in the industry at present, alkaline liquid such as sodium hydroxide, lime water or ammonia water is generally adopted to carry out saponification pretreatment on acidic phosphorus (phosphine) extractant before extraction reaction, and Na is adopted⁺、Ca²⁺Or NH₄ ⁺The plasma pre-replaces hydrogen ions in the acidic phosphorus (phosphine) extractant. Na when extraction reaction takes place⁺、Ca²⁺Or NH₄ ⁺Performing replacement reaction with metal ions to enter the water phase to make the hydrogen ion concentration of the water phaseNo change occurs. However, the cost of using sodium hydroxide as a saponifier is relatively high, and the content of sodium salt in saponified wastewater exceeds the standard, so that the problem of difficulty in comprehensive utilization of industrial waste salt is brought. The use of lime as a saponifier will lead to an excessive impurity content in the metal product. Although the cost is relatively low by adopting the strong ammonia water as the saponifier, the ammonia nitrogen in the wastewater can be difficult to treat, and the environmental pollution is caused.

Therefore, an extraction system which is environment-friendly, low in cost, high in extraction rate and high in separation coefficient is researched and developed, sodium ions and ammonium ions in the saponified wastewater are not overproof, and the extraction system has double values of cleanness, environmental protection and economic benefit.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for selectively extracting and recovering aluminum from a lithium sodium potassium aluminum sulfate solution. The method can realize the high-efficiency selective separation of aluminum ions and lithium, sodium and potassium ions in a wider pH value range, has high back extraction rate of the aluminum ions, and obtains high-purity Al₂(SO₄)₃·18H₂O。

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a method for selectively extracting and recovering aluminum from a lithium sodium potassium aluminum sulfate-containing solution, which comprises the following steps:

1) mixing the lithium sodium potassium aluminum sulfate solution with the extraction organic phase, and extracting and layering to obtain a loaded organic phase and a lithium sodium potassium sulfate solution;

2) mixing the loaded organic phase and the stripping solution, and performing stripping and layering to obtain an organic phase and an aluminum sulfate solution;

3) the aluminum sulfate solution is evaporated, concentrated, cooled and crystallized in sequence to obtain Al₂(SO₄)₃·18H₂O。

Preferably, the extraction organic phase in the step 1) comprises an extracting agent, a modifier and a diluent in a volume ratio of 10-40: 2.5-10: 50-87.5.

Preferably, the extracting agent comprises one or more of mono-alkyl phenyl phosphate, dialkyl phenyl phosphate and trialkyl phenyl phosphate, wherein the alkyl is a straight-chain alkyl and/or branched-chain alkyl, and the straight-chain alkyl and the branched-chain alkyl independently contain 4-18 carbon atoms; the modifier comprises n-butanol and/or isobutanol; the diluent is sulfonated kerosene.

Preferably, the volume ratio of the lithium sodium potassium aluminum sulfate solution in the step 1) to the extracted organic phase is 1-4: 1-4; the extraction temperature is 25-50 ℃, the extraction time is 6-15 min, and the extraction adopts counter-current extraction with 2-8 stages.

Preferably, in the lithium sodium potassium aluminum sulfate solution in the step 1), the concentration of lithium ions is 0.5-15 g/L, the concentration of sodium ions is 5-25 g/L, the concentration of potassium ions is 1.5-15 g/L, and the concentration of aluminum ions is 2-35 g/L; the pH value of the lithium sodium potassium aluminum sulfate solution is 2-5.

Preferably, before the mixing in the step 2), the loaded organic phase is washed by water in a counter-current manner; the volume ratio of the loaded organic phase to water is 1-5: 1; the temperature of the countercurrent washing is 25-50 ℃, and the number of stages is 1-3.

Preferably, the strip liquor in the step 2) is a sulfuric acid solution with acidity of 20-300 g/L; the volume ratio of the loaded organic phase to the stripping solution is 1-10: 1-3.

Preferably, the temperature of the back extraction in the step 2) is 25-50 ℃, the time is 6-15 min, and the back extraction adopts counter-current back extraction with the stage number of 1-5.

The beneficial effects of the invention include:

1) the method can realize the high-efficiency selective separation of aluminum ions and lithium, sodium and potassium ions in a wider pH value range, has high extraction rate and back extraction rate on the aluminum ions, and obtains high-purity Al₂(SO₄)₃·18H₂O。

2) The extraction organic phase of the invention is easy to be back extracted and regenerated, the extractant does not need saponification treatment, no waste water is generated in the extraction-back extraction process, the cost is greatly reduced, and the invention has higher economic benefit and environmental benefit.

Drawings

FIG. 1 is a flow chart of a process for selectively extracting and recovering aluminum from a lithium sodium potassium aluminum sulfate-containing solution in examples 1 to 4.

Detailed Description

The invention provides a method for selectively extracting and recovering aluminum from a lithium sodium potassium aluminum sulfate-containing solution, which comprises the following steps:

1) mixing the lithium sodium potassium aluminum sulfate solution with the extraction organic phase, and extracting and layering to obtain a loaded organic phase and a lithium sodium potassium sulfate solution;

2) mixing the loaded organic phase and the stripping solution, and performing stripping and layering to obtain an organic phase and an aluminum sulfate solution;

3) the aluminum sulfate solution is evaporated, concentrated, cooled and crystallized in sequence to obtain Al₂(SO₄)₃·18H₂O。

The organic phase extracted in step 1) of the present invention preferably comprises an extractant, a modifier and a diluent; the volume ratio of the extracting agent to the modifying agent to the diluting agent is preferably 10-40: 2.5-10: 50-87.5, and more preferably 20-30: 5-8: 60-75; more preferably 23 to 25:6 to 7:65 to 70.

The extracting agent of the invention preferably comprises one or more of monoalkylphenyl phosphate, dialkyl phenyl phosphate and trialkyl phenyl phosphate, and when the extracting agent simultaneously comprises a plurality of components, the components are preferably mixed in equal mass; the alkyl is preferably a straight-chain alkyl and/or a branched-chain alkyl, and the straight-chain alkyl and the branched-chain alkyl preferably independently contain 4-18 carbon atoms, and further preferably contain 8-12 carbon atoms; the modifier preferably comprises n-butanol and/or isobutanol, when the modifier comprises both n-butanol and isobutanol, the two are preferably mixed in equal volumes; the diluent is preferably sulfonated kerosene.

The volume ratio of the lithium sodium potassium aluminum sulfate solution in the step 1) to the extracted organic phase is preferably 1-4: 1-4, more preferably 2-3: 2-3, and more preferably 1: 1; the extraction temperature is preferably 25-50 ℃, more preferably 30-45 ℃, and more preferably 35-40 ℃; the extraction time is preferably 6-15 min, more preferably 8-12 min, and even more preferably 10 min; the extraction is preferably performed by countercurrent extraction, the number of stages of countercurrent extraction is preferably 2-8, more preferably 3-7, and even more preferably 5-6.

In the lithium sodium potassium aluminum sulfate solution in the step 1), the concentration of lithium ions is preferably 0.5-15 g/L, more preferably 3-12 g/L, and even more preferably 5-8 g/L; the concentration of the sodium ions is preferably 5-25 g/L, more preferably 10-20 g/L, and even more preferably 13-16 g/L; the concentration of potassium ions is preferably 1.5-15 g/L, more preferably 3-12 g/L, and even more preferably 5-8 g/L; the concentration of aluminum ions is preferably 2-35 g/L, more preferably 5-30 g/L, and even more preferably 10-20 g/L; the pH value of the lithium sodium potassium aluminum sulfate solution is preferably 2-5, and more preferably 3-4.

Before the mixing in the step 2), the loaded organic phase is preferably subjected to counter-current washing by water and then clarified and layered; returning the washed water to raffinate; the volume ratio of the loaded organic phase to the water is preferably 1-5: 1, more preferably 2-4: 1, and even more preferably 3: 1; the temperature of the countercurrent washing is preferably 25-50 ℃, more preferably 30-45 ℃, and more preferably 35-40 ℃; the number of stages of the countercurrent washing is preferably 1 to 3, and more preferably 2.

The counter-extraction solution in the step 2) is preferably a sulfuric acid solution, and the acidity of the sulfuric acid solution is preferably 20-300 g/L, more preferably 50-200 g/L, and even more preferably 100-150 g/L; the volume ratio of the loaded organic phase to the stripping solution is preferably 1-10: 1-3, more preferably 3-7: 2, and even more preferably 5-6: 2.

The temperature of the back extraction in the step 2) is preferably 25-50 ℃, more preferably 30-45 ℃, and more preferably 35-40 ℃; the time for the back extraction is preferably 6-15 min, more preferably 8-12 min, and even more preferably 10 min; the counter-current back extraction is preferably performed, the number of stages of the counter-current back extraction is preferably 1-5, more preferably 2-4, and even more preferably 3; the stripped organic phase is preferably returned to the extraction step of step 1).

Preferably, neutralizing and purifying the lithium sodium potassium sulfate solution in the step 1) to obtain calcium magnesium aluminum slag and pure lithium sodium potassium sulfate solution; the pure lithium sodium potassium sulfate solution is preferably precipitated by sodium carbonate to obtain lithium carbonate and sodium potassium sulfate solution; preferably, the sodium potassium sulfate solution is subjected to evaporation concentration, cooling crystallization and filtering separation in sequence to obtain sodium sulfate decahydrate and potassium sulfate.

The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.

Example 1

Mixing the components in a volume ratio of 40: 10:50 of di (4-tert-octylphenyl) phosphate, n-butanol and sulfonated kerosene were mixed to obtain an extracted organic phase. And preparing a lithium sodium potassium aluminum sulfate solution with the pH value of 4.5, wherein the concentration of aluminum ions is 12.5g/L, the concentration of lithium ions is 3.6g/L, the concentration of sodium ions is 18g/L, and the concentration of potassium ions is 12 g/L.

Uniformly mixing the extracted organic phase and the lithium sodium potassium aluminum sulfate solution according to the volume ratio of 3:1, carrying out 3-level countercurrent extraction at 40 ℃ for 8min, and then clarifying and layering to obtain the loaded organic phase and the lithium sodium potassium aluminum sulfate solution. The loaded organic phase is subjected to 1-stage countercurrent washing at 40 ℃ by adopting water with the same volume, is clarified and layered, and the water washing liquid and the raffinate are mixed.

Uniformly mixing the washed loaded organic phase and a sulfuric acid solution (acidity is 300g/L) according to the volume ratio of 3:1, carrying out 3-stage counter-current back extraction at 40 ℃ for 12min, and then clarifying and demixing to obtain an organic phase and an aluminum sulfate solution. The aluminum sulfate solution is evaporated, concentrated, cooled and crystallized in sequence to obtain Al₂(SO₄)₃·18H₂O。

The extraction rate of aluminum ions in example 1 was 99.24%, and lithium, sodium, and potassium were not extracted; the back extraction rate of the aluminum ions is 98.85%, and lithium ions, sodium ions and potassium ions are not detected in the back extraction solution. Al (Al)₂(SO₄)₃·18H₂In O, Al₂(SO₄)₃·18H₂The content of O is more than or equal to 99.0 wt%, and lithium ions, sodium ions and potassium ions are not detected.

High purity Al₂(SO₄)₃·18H₂The element content requirement standard of O is as follows: na content of not more than 0.02 wt%, Mg content of not more than 0.002 wt%, K content of not more than 0.005 wt%, Ca content of not more than 0.01 wt%, Fe content of not more than 0.003 wt%, heavy metal (in terms of Pb) content of not more than 0.001 wt%, Al of example 1₂(SO₄)₃·18H₂O is in accordance with high purity Al₂(SO₄)₃·18H₂And (4) standard of O.

Example 2

Mixing the components in a volume ratio of 40: 10: mixing 50 parts of extracting agent, n-butyl alcohol and sulfonated kerosene to obtain an extracted organic phase, wherein the extracting agent comprises phosphoric acid (4-tert-octylbenzene) ester and phosphoric acid di (4-tert-octylbenzene) ester in a mass ratio of 15: 85. Preparing a lithium sodium potassium aluminum sulfate solution with the pH value of 2, wherein the concentration of aluminum ions is 9.36g/L, the concentration of lithium ions is 2.46g/L, the concentration of sodium ions is 15g/L, and the concentration of potassium ions is 12.5 g/L.

Uniformly mixing the extracted organic phase and the lithium sodium potassium aluminum sulfate solution according to the volume ratio of 1:1, carrying out 5-level countercurrent extraction at 30 ℃ for 10min, and then clarifying and layering to obtain the loaded organic phase and the lithium sodium potassium aluminum sulfate solution. Mixing the loaded organic phase with water in a volume ratio of 5:1, carrying out 2-stage countercurrent washing on the loaded organic phase at 30 ℃, clarifying and layering, and mixing water washing liquid and raffinate.

Uniformly mixing the washed loaded organic phase and a sulfuric acid solution (the acidity is 250g/L) according to the volume ratio of 1:1, carrying out 2-stage counter-current back extraction at 30 ℃ for 8min, and then clarifying and demixing to obtain an organic phase and an aluminum sulfate solution. The aluminum sulfate solution is evaporated, concentrated, cooled and crystallized in sequence to obtain Al₂(SO₄)₃·18H₂O。

The extraction rate of aluminum ions in example 2 was 99.92%, and lithium, sodium, and potassium were not extracted; the back extraction rate of the aluminum ions is 98.94%, and lithium ions, sodium ions and potassium ions are not detected in the back extraction solution. Al (Al)₂(SO₄)₃·18H₂In O, Al₂(SO₄)₃·18H₂The content of O is more than or equal to 99.0 wt%, and lithium ions, sodium ions and potassium ions are not detected. Al of example 2₂(SO₄)₃·18H₂O is in accordance with high purity Al₂(SO₄)₃·18H₂And (4) standard of O.

Example 3

Mixing the components in a volume ratio of 30: 5: 65, and mixing the extractant, the isobutanol, and the sulfonated kerosene to obtain an extracted organic phase, wherein the extractant comprises the phosphoric acid (dodecylphenyl) ester and the phosphoric acid di (dodecylphenyl) ester in a mass ratio of 10: 90. And preparing a lithium sodium potassium aluminum sulfate solution with the pH value of 3, wherein the concentration of aluminum ions is 6.13g/L, the concentration of lithium ions is 1.95g/L, the concentration of sodium ions is 8.53g/L, and the concentration of potassium ions is 6.21 g/L.

Uniformly mixing the extracted organic phase and the lithium sodium potassium aluminum sulfate solution according to the volume ratio of 1:1, carrying out 4-stage countercurrent extraction at 25 ℃ for 12min, and then clarifying and layering to obtain the loaded organic phase and the lithium sodium potassium aluminum sulfate solution. Mixing the loaded organic phase and water in a volume ratio of 2:1, carrying out 2-stage countercurrent washing on the loaded organic phase at 25 ℃, clarifying and layering, and mixing water washing liquid and raffinate.

Uniformly mixing the washed loaded organic phase and a sulfuric acid solution (acidity is 200g/L) according to the volume ratio of 3:1, carrying out 4-stage counter-current back extraction at 25 ℃ for 12min, and then clarifying and demixing to obtain an organic phase and an aluminum sulfate solution. The aluminum sulfate solution is evaporated, concentrated, cooled and crystallized in sequence to obtain Al₂(SO₄)₃·18H₂O。

The extraction rate of aluminum ions in example 3 was 99.87%, and lithium, sodium, and potassium were not extracted; the back extraction rate of the aluminum ions was 98.36%, and no lithium ions, sodium ions, or potassium ions were detected in the back extraction solution. Al (Al)₂(SO₄)₃·18H₂In O, Al₂(SO₄)₃·18H₂The content of O is more than or equal to 99.0 wt%, and lithium ions, sodium ions and potassium ions are not detected. Al of example 3₂(SO₄)₃·18H₂O is in accordance with high purity Al₂(SO₄)₃·18H₂And (4) standard of O.

Example 4

Mixing the components in a volume ratio of 20: 4: 76 of dodecylphenyl phosphate, n-butanol and sulfonated kerosene, to give an organic extract. Preparing a lithium sodium potassium aluminum sulfate solution with the pH value of 3.5, wherein the concentration of aluminum ions is 20g/L, the concentration of lithium ions is 10g/L, the concentration of sodium ions is 6g/L, and the concentration of potassium ions is 10 g/L.

Uniformly mixing the extracted organic phase and the lithium sodium potassium aluminum sulfate solution according to the volume ratio of 1:2, carrying out 6-stage countercurrent extraction at 45 ℃ for 12min, and then clarifying and layering to obtain the loaded organic phase and the lithium sodium potassium aluminum sulfate solution. 3-stage countercurrent washing is carried out on the loaded organic phase at 45 ℃ by adopting water with the same volume, the loaded organic phase is clarified and layered, and water washing liquid and raffinate are mixed.

Uniformly mixing the washed loaded organic phase and a sulfuric acid solution (acidity is 100g/L) according to the volume ratio of 1:2, carrying out 4-stage counter-current back extraction at 45 ℃ for 12min, and then clarifying and demixing to obtain an organic phase and an aluminum sulfate solution. The aluminum sulfate solution is evaporated, concentrated, cooled and crystallized in sequence to obtain Al₂(SO₄)₃·18H₂O。

The extraction rate of aluminum ions in example 4 was 99.95%, and lithium, sodium, and potassium were not extracted; the back extraction rate of the aluminum ions is 99.12%, and lithium ions, sodium ions and potassium ions are not detected in the back extraction solution. Al (Al)₂(SO₄)₃·18H₂In O, Al₂(SO₄)₃·18H₂The content of O is more than or equal to 99.2 wt%, and lithium ions, sodium ions and potassium ions are not detected. Al of example 4₂(SO₄)₃·18H₂O is in accordance with high purity Al₂(SO₄)₃·18H₂And (4) standard of O.

Examples 1-4 the process flow for selective extraction recovery of aluminum from lithium sodium potassium aluminum sulfate-containing solutions is shown in FIG. 1.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.