CN114107662B - A kind of phosphate extractant and its method for extracting and separating lithium manganese leachate - Google Patents

Abstract

The invention provides a phosphate extractant and a method for extracting and separating lithium manganese leaching liquid by using the same, belonging to the technical field of hydrometallurgical separation. The invention obtains an extracted organic phase by mixing a phosphate ester extractant, a modifier and a diluent, and then carries out multistage extraction under the conditions of preset O/A ratio, temperature and time, so that manganese ions are extracted into the organic phase, and lithium ions are reserved in raffinate; and (3) carrying out multistage washing on the organic phase loaded with manganese by pure water, and then carrying out multistage back extraction on the manganese in the organic phase by sulfuric acid to enable the manganese to enter a water phase, so as to produce a pure manganese sulfate solution. Compared with the chemical precipitation manganese separation process, the method can avoid the generation of waste residues such as sodium sulfate, ammonium sulfate, calcium sulfate and the like, and also eliminates saponification waste liquid generated in the saponification process in the traditional process of extracting manganese by the phosphoric acid extractant, thereby realizing the efficient separation and green extraction of lithium and manganese in solution.

Description

A kind of phosphate extractant and its method for extracting and separating lithium manganese leachate

Technical field

The invention relates to the technical field of hydrometallurgical separation, and in particular to a phosphate extractant and a method for extracting and separating lithium manganese leachate.

Background technique

Waste lithium-ion batteries are rich in valuable resources such as lithium, nickel, cobalt, manganese, copper, aluminum, and graphite. In order to alleviate the supply pressure of key energy metal resources and eliminate potential environmental risks, the recycling of valuable metals in waste lithium-ion batteries has become a hot topic in the lithium battery industry. Waste lithium battery recycling processes include fire and wet processes. Most domestic lithium battery recycling companies use wet processes. Patent CN107181014A discloses a method for recycling waste lithium manganate batteries. This method first disassembles and washes the lithium manganate batteries to obtain positive electrode materials. After high-temperature treatment, the valuable metals are leached out with organic acids, and then separated by solvent extraction. Lithium and manganese in leachate. CN111254294A discloses a method for selectively extracting lithium from waste lithium-ion battery powder and electrolytically separating and recovering manganese dioxide. This method mainly adopts the "sulfation roasting-baked sand water leaching" technical route to selectively enrich lithium in water leaching. liquid to achieve efficient extraction of lithium from the source. In order to obtain a higher lithium leaching rate, the process needs to increase the proportion of concentrated sulfuric acid, which causes a small amount of manganese to enter the aqueous solution along with lithium, and there is also a subsequent separation problem of lithium and manganese.

The separation methods of lithium and manganese in solution mainly include chemical precipitation, electrochemical deposition and solvent extraction. Although the chemical precipitation method (neutralization, hydrolysis precipitation and sulfide precipitation) can quickly precipitate manganese, it is easy to introduce new impurity ions, which not only adversely affects the subsequent separation and recovery of lithium and the purity of lithium salt products, but also produces sodium sulfate and ammonium sulfate. , calcium sulfate and other wastes. Electrochemical deposition technology can recover manganese dioxide powder, but it also has the disadvantages of low current efficiency, high power consumption, and incomplete separation of lithium and manganese. The organic phosphoric acid solvent extraction method (P204, P507) has the characteristics of high separation efficiency, easy automation and continuous operation, and can achieve complete separation of lithium and manganese. In order to maintain a stable pH value of the feed liquid during the extraction process to obtain a higher extraction rate, the extraction agent needs to be saponified and pre-treated, making it difficult to separate Na ⁺ , NH ₄ ⁺ and Li ⁺ in the raffinate, and producing a large amount of sodium sulfate. , ammonium sulfate and other industrial waste salts.

Therefore, how to obtain a process for efficient separation and extraction of lithium and manganese in the leach solution without producing industrial salt waste is an urgent technical problem that needs to be solved.

Contents of the invention

The object of the present invention is to provide a phosphate extractant and a method for extracting and separating lithium and manganese leachate. The extraction and separation method of the present invention achieves the effect of efficiently separating lithium and manganese and avoiding the generation of industrial salt waste.

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

The invention provides a phosphate ester extraction agent, which contains one or two of the following structural formulas,

The invention provides a method for extracting and separating lithium manganese leachate using a phosphate extractant, which includes the following steps:

1) Prepare the extracted organic phase: mix the modifier, diluent and phosphate extractant to obtain the extracted organic phase;

2) Manganese extraction: Use the lithium manganese leachate as the extraction liquid, mix the extracted organic phase and the extraction liquid for multi-stage extraction, and obtain the manganese-loaded organic phase and the lithium-containing raffinate;

3) Washing of the manganese-loaded organic phase: The manganese-loaded organic phase is washed in multiple stages to remove the lithium contained in the organic phase, and the obtained washing liquid is combined with the lithium-containing raffinate as a lithium salt preparation feed liquid;

4) Manganese stripping: Use sulfuric acid solution to carry out multi-stage stripping on the manganese-loaded organic phase after washing in step 3), so that the manganese in the organic phase enters the aqueous phase to obtain a manganese sulfate solution, and the stripped organic phase is returned to the manganese extraction step.

Further, the modifier is n-butanol and/or isobutanol;

The diluent contains sulfonated kerosene.

Further, the volume ratio of the phosphate extractant, modifier and diluent is 20-50:5-15:35-75.

Further, in step 2), the pH value of the lithium manganese leach solution is 0.5-6, the lithium content is 3-35g/L, and the manganese content is 5-85g/L.

Further, in step 2), the conditions of the multi-stage extraction are: O/A ratio is 1:3~3:1, extraction temperature is 20~60°C, extraction time is 5~15min, extraction stage The number is 2 to 10.

Further, in step 3), the multi-stage washing conditions are: O/A ratio is 1:1~4:1, washing temperature is 25~60°C, washing time is 5~15min, washing stage The number is 2 to 4.

Further, in step 4), the conditions for the multi-stage stripping are: the O/A ratio is 1:1~3:1, the concentration of the sulfuric acid solution is 4~6mol/L, and the stripping temperature is 20~ 60°C, the stripping time is 5 to 15 minutes, and the stripping stages are 2 to 6.

Further, the equipment for extraction, washing and stripping is one of a centrifugal extractor, a mixing and clarifying tank and an extraction tower.

Beneficial effects of the present invention:

Compared with the chemical precipitation manganese separation process, the present invention can avoid the generation of waste residues such as sodium sulfate, ammonium sulfate, calcium sulfate, etc., and also eliminates the saponification waste liquid produced by the traditional phosphoric acid extractant saponification process; and avoids the waste liquid after manganese removal. Solve the problem of separation of lithium and impurity ions, greatly improve the lithium recovery rate, and achieve efficient separation and green extraction of lithium and manganese in the solution.

Detailed ways

The invention provides a phosphate ester extraction agent, which contains one or two of the following structural formulas,

In the present invention, the phosphate extractant is preferably

The invention provides a method for extracting and separating lithium manganese leachate using a phosphate extractant, which includes the following steps:

1) Prepare the extracted organic phase: mix the modifier, diluent and phosphate extractant to obtain the extracted organic phase;

2) Manganese extraction: Use the lithium manganese leachate as the extraction liquid, mix the extracted organic phase and the extraction liquid for multi-stage extraction, and obtain the manganese-loaded organic phase and the lithium-containing raffinate;

3) Washing of the manganese-loaded organic phase: The manganese-loaded organic phase is washed in multiple stages to remove the lithium contained in the organic phase, and the obtained washing liquid is combined with the lithium-containing raffinate as a lithium salt preparation feed liquid;

4) Manganese stripping: Use sulfuric acid solution to carry out multi-stage stripping on the manganese-loaded organic phase after washing in step 3), so that the manganese in the organic phase enters the aqueous phase to obtain a manganese sulfate solution, and the stripped organic phase is returned to the manganese extraction step.

In the present invention, the modifier is n-butanol and/or isobutanol, preferably n-butanol.

In the present invention, the diluent is preferably sulfonated kerosene.

In the present invention, the volume ratio of the phosphate ester extractant, modifier and diluent is 20~50:5~15:35~75, preferably 25~45:8~12:40~70, further preferably It is 30～40:15:45～65.

In the present invention, in step 2), the pH value of the lithium manganese leachate is 0.5-6, the lithium content is 3-35g/L, and the manganese content is 5-85g/L; preferably, the pH value of the lithium-manganese leachate is is 1 to 5, the lithium content is 5 to 30g/L, and the manganese content is 20 to 70g/L; further preferably, the pH value of the lithium manganese leach solution is 2 to 4, the lithium content is 10 to 20g/L, and the manganese content is 30～60g/L.

In the present invention, in step 2), the conditions of the multi-stage extraction are: O/A ratio is 1:3~3:1, extraction temperature is 20~60°C, extraction time is 5~15min, The extraction stages are 2 to 10; preferably, the O/A ratio is 1:2 to 2:1, the extraction temperature is 30 to 50°C, the extraction time is 8 to 12 minutes, and the extraction stages are 3 to 7; Further preferably, the O/A ratio is 1:1-4:3, the extraction temperature is 35-45°C, the extraction time is 10 min, and the extraction stages are 4-6.

In the present invention, in step 3), the multi-stage washing conditions are: O/A ratio is 1:1~4:1, washing temperature is 25~60°C, washing time is 5~15min, The number of washing levels is 2 to 4; preferably, the O/A ratio is 2:1 to 3:1, the washing temperature is 30 to 50°C, the washing time is 8 to 12 minutes, and the number of washing levels is 3 to 4; Further preferably, the O/A ratio is 3:1, the washing temperature is 40°C, the washing time is 10 minutes, and the number of washing levels is 4.

In the present invention, in step 4), the conditions for the multi-stage stripping are: the O/A ratio is 1:1 to 3:1, the concentration of the sulfuric acid solution is 4 to 6 mol/L, and the stripping temperature is 20~60℃, the stripping time is 5~15min, the number of stripping stages is 2~6; preferably, the O/A ratio is 3:2~5:2, and the concentration of the sulfuric acid solution is 5~6mol/L , the stripping temperature is 30 to 50°C, the stripping time is 8 to 12 minutes, and the number of stripping stages is 3 to 4; further preferably, the O/A ratio is 2:1, and the concentration of the sulfuric acid solution is 5.5 mol. /L, the stripping temperature is 40°C, the stripping time is 10min, and the number of stripping stages is 4.

In the present invention, the equipment for extraction, washing and stripping is one of a centrifugal extractor, a mixing and clarifying tank and an extraction tower, preferably a centrifugal extractor.

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

Example 1

The initial pH value of the lithium manganese leach solution is 3, and the valuable metal contents are Li 20g/L and Mn 40g/L respectively. Follow the following steps to carry out clean and efficient extraction and separation of lithium and manganese in the mixing and clarifying tank:

(1) Prepare and extract the organic phase: select dialkyl phosphate (Ⅱ) as the extraction agent, n-butanol as the modifier, and sulfonated kerosene as the diluent. According to "40% extraction agent + 10% modifier + dilution The organic phase was extracted using a volume ratio of 50%.

(2) Manganese extraction: Using the extraction organic phase configured in step (1), the lithium-containing manganese leachate was carried out under the process conditions of O/A ratio of 1:2, extraction temperature of 40°C, and extraction time of 10 minutes. Extract manganese in stage 8 to obtain manganese-loaded organic phase and lithium-containing raffinate. After testing and calculation, the manganese extraction rate can reach 99.89%, while the lithium co-extraction rate is only 2.25%.

(3) Washing of manganese-loaded organic phase: Pure water is used as the detergent. Under the process conditions of O/A ratio of 3:1, washing temperature of 40°C, and washing time of 8 minutes, the manganese-loaded organic phase is washed in level 3. Wash to remove the entrained lithium in the organic phase. After the washing liquid is circulated several times, it is combined with the lithium-containing raffinate to prepare the lithium salt preparation liquid. After testing and calculation, the lithium removal rate is 99.39%, and the manganese removal rate is <1%.

(4) Manganese stripping: using 5mol/L sulfuric acid solution, under the process conditions of O/A ratio of 1:1, stripping temperature of 40°C, and stripping time of 10 minutes, the washed manganese-loaded organic phase Perform 4-stage back extraction to obtain pure manganese sulfate solution. After testing and calculation, the manganese stripping rate was 99.50%.

Example 2

The initial pH value of the lithium manganese leach solution is 4, and the valuable metal contents are Li 18g/L and Mn 8g/L respectively. Follow the following steps to carry out clean and efficient extraction and separation of lithium and manganese in the mixing and clarifying tank:

(1) Prepare and extract the organic phase: select monoalkyl phosphate (Ⅰ) as the extraction agent, n-butanol as the modifier, and sulfonated kerosene as the diluent. According to "extractant 35% + modifier 15% + dilution The organic phase was extracted using a volume ratio of 50%.

(2) Manganese extraction: Using the extraction organic phase configured in step (1), the lithium-containing manganese leachate was carried out under the process conditions of O/A ratio of 1:3, extraction temperature of 45°C, and extraction time of 6 minutes. 3-stage extraction of manganese to obtain manganese-loaded organic phase and lithium-containing raffinate. After testing and calculation, the manganese extraction rate can reach 99.94%, while the lithium co-extraction rate is only 1.53%.

(3) Washing of manganese-loaded organic phase: Pure water is used as the detergent. Under the process conditions of O/A ratio of 4:1, washing temperature of 45°C, and washing time of 8 minutes, the manganese-loaded organic phase is washed in level 2. Wash to remove the entrained lithium in the organic phase. After the washing liquid is circulated several times, it is combined with the lithium-containing raffinate to prepare the lithium salt preparation liquid. After testing and calculation, the lithium removal rate is 99.62%, and the manganese removal rate is <1%.

(4) Manganese stripping: using 4mol/L sulfuric acid solution, under the process conditions of O/A ratio of 2.5:1, stripping temperature of 40°C, and stripping time of 10 minutes, the washed manganese-loaded organic phase Perform 3-stage back extraction to obtain pure manganese sulfate solution. After testing and calculation, the manganese stripping rate was 99.61%.

Example 3

The initial pH value of the lithium manganese leach solution is 2, and the valuable metal contents are Li 10g/L and Mn 30g/L respectively. Follow the following steps to carry out clean and efficient extraction and separation of lithium and manganese in the mixing and clarifying tank:

(1) Prepare and extract the organic phase: select "20wt% monoalkyl phosphate (Ⅰ) + 80wt% dialkyl phosphate (II)" as the extraction agent, isobutanol as the modifier, and sulfonated kerosene as the diluent , configure the extraction organic phase according to the volume ratio of "40% extraction agent + 15% modifier + 45% diluent".

(2) Manganese extraction: Using the extraction organic phase configured in step (1), the lithium-containing manganese leachate was carried out under the process conditions of O/A ratio of 1:1, extraction temperature of 40°C, and extraction time of 10 minutes. 4-stage extraction of manganese to obtain manganese-loaded organic phase and lithium-containing raffinate. After testing and calculation, the manganese extraction rate can reach 99.81%, while the lithium co-extraction rate is only 1.81%.

(3) Washing of manganese-loaded organic phase: Pure water is used as the detergent. Under the process conditions of O/A ratio of 2:1, washing temperature of 40°C, and washing time of 10 minutes, the manganese-loaded organic phase is washed in level 2. Wash to remove the entrained lithium in the organic phase. After the washing liquid is circulated several times, it is combined with the lithium-containing raffinate to prepare the lithium salt preparation liquid. After testing and calculation, the lithium removal rate is 99.56%, and the manganese removal rate is <1%.

(4) Manganese stripping: using 6mol/L sulfuric acid solution, under the process conditions of O/A ratio of 2:1, stripping temperature of 40°C, and stripping time of 10 minutes, the washed manganese-loaded organic phase Perform 4-stage back extraction to obtain pure manganese sulfate solution. After testing and calculation, the manganese stripping rate was 99.77%.

Example 4

The initial pH value of the lithium manganese leach solution is 4, and the valuable metal contents are Li 15g/L and Mn 5g/L respectively. Follow the following steps to carry out clean and efficient extraction and separation of lithium and manganese in the mixing and clarifying tank:

(1) Prepare and extract the organic phase: select “10wt% monoalkyl phosphate (Ⅰ) + 90wt% dialkyl phosphate (Ⅱ)” as the extraction agent, isobutanol as the modifier, and sulfonated kerosene as the diluent , configure the extraction organic phase according to the volume ratio of "25% extraction agent + 5% modifier + 60% diluent".

(2) Manganese extraction: Using the extraction organic phase configured in step (1), the lithium-containing manganese leachate was carried out under the process conditions of O/A ratio of 1:2.5, extraction temperature of 35°C, and extraction time of 8 minutes. The manganese is extracted in the second stage to obtain the manganese-loaded organic phase and the lithium-containing raffinate. After testing and calculation, the manganese extraction rate can reach 99.35%, while the lithium co-extraction rate is only 1.19%.

(3) Washing of manganese-loaded organic phase: Pure water is used as the detergent. Under the process conditions of O/A ratio of 2.5:1, washing temperature of 35°C, and washing time of 8 minutes, the manganese-loaded organic phase is washed in Level 2. Wash to remove the entrained lithium in the organic phase. After the washing liquid is circulated several times, it is combined with the lithium-containing raffinate to prepare the lithium salt preparation liquid. After testing and calculation, the lithium removal rate is 99.37%, and the manganese removal rate is <1%.

(4) Manganese stripping: using 5mol/L sulfuric acid solution, under the process conditions of O/A ratio of 2:1, stripping temperature of 35°C, and stripping time of 8 minutes, the washed manganese-loaded organic phase Perform 2-stage back extraction to obtain pure manganese sulfate solution. After testing and calculation, the manganese stripping rate was 99.83%.

As can be seen from the above examples, the present invention provides a phosphate ester extractant and a method for extracting and separating lithium manganese leachate. Through the extraction and separation method of the present invention, lithium and manganese in the lithium-containing manganese leachate can be efficiently extracted and separated. The stripping rate of manganese is as high as 99.83%, and the separation rate of lithium is as high as 99.62%, achieving an efficient, green, and waste-free extraction and separation effect, and providing a more economical and feasible method for the comprehensive treatment of lithium and manganese leachate.

The above are only preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications can also be made. should be regarded as the protection scope of the present invention.

Claims (6)

1. A method for extracting and separating lithium manganese leachate using a phosphate extractant, which is characterized in that it includes the following steps: 1) Prepare the extracted organic phase: mix the modifier, diluent and phosphate extractant to obtain the extracted organic phase; 2) Manganese extraction: Use the lithium manganese leachate as the extraction liquid, mix the extracted organic phase and the extraction liquid for multi-stage extraction, and obtain the manganese-loaded organic phase and the lithium-containing raffinate; 3) Washing of the manganese-loaded organic phase: The manganese-loaded organic phase is washed in multiple stages to remove the lithium contained in the organic phase, and the obtained washing liquid is combined with the lithium-containing raffinate as a lithium salt preparation feed liquid; 4) Manganese stripping: Use sulfuric acid solution to carry out multi-stage stripping on the manganese-loaded organic phase after washing in step 3), so that the manganese in the organic phase enters the aqueous phase to obtain a manganese sulfate solution, and the stripped organic phase is returned to the manganese extraction step; The phosphate ester extraction agent includes one or two of the following structural formulas, The conditions of the multi-stage extraction are: O/A ratio is 1:2~1:3, extraction temperature is 20~60°C, extraction time is 5~15min, and the number of extraction stages is 2~10; The conditions for the multi-stage stripping are: the O/A ratio is 1:1~3:1, the concentration of the sulfuric acid solution is 4~6mol/L, the stripping temperature is 20~60°C, and the stripping time is 5 to 15 minutes, and the number of stripping stages is 2 to 6. 2. The method of extraction and separation according to claim 1, characterized in that the modifier is n-butanol and/or isobutanol; The diluent contains sulfonated kerosene. 3. The extraction and separation method according to claim 1 or 2, characterized in that the volume ratio of the phosphate ester extractant, modifier and diluent is 20-50:5-15:35-75. 4. The method of extraction and separation according to claim 3, characterized in that in step 2), the pH value of the lithium manganese leach solution is 0.5~6, the lithium content is 3~35g/L, and the manganese content is 5~ 85g/L. 5. The method of extraction and separation according to claim 1, characterized in that, in step 3), the conditions of the multi-stage washing are: O/A ratio is 1:1~4:1, and the washing temperature is 25～60℃, washing time is 5～15min, washing level is 2～4. 6. The extraction and separation method according to claim 4 or 5, characterized in that the equipment for extraction, washing and stripping is one of a centrifugal extractor, a mixing and clarifying tank and an extraction tower.