A method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid

Abstract

The invention discloses a method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid, and belongs to the field of high-purity manganese-based material preparation and electrolytic manganese dioxide clean production. The invention adjusts the pH of the electrolytic manganese dioxide tail liquid to prepare a manganese sulfate mother liquor, and then continuously inputs a manganese precipitant made of ammonium bicarbonate and ammonium sulfite, and performs solid-liquid separation after sufficient reaction. The solid phase product is dried to obtain a composite manganese salt; the composite manganese salt is then rotary calcined, ultrasonically washed after cooling, and finally dried to obtain a battery-grade sponge-like manganese trioxide. The invention uses ammonium bicarbonate and ammonium sulfite as manganese precipitants, and uses the composite manganese salt as an intermediate product. The calcium and magnesium impurities undergo multiple phase changes to achieve deep impurity removal of calcium and magnesium; the invention does not generate new pollutants, the process flow is short, and the prepared battery-grade sponge-like manganese trioxide has a rich pore structure, stable tap density and specific surface area, and is an excellent raw material for high-performance new energy batteries.

Description

Technical Field

[0001] The invention belongs to the field of high-purity manganese-based material preparation and electrolytic manganese dioxide clean production, and specifically relates to a method for preparing battery-grade sponge-like manganese trioxide by using electrolytic manganese dioxide tail liquid. Background Art

[0002] Electrolytic manganese dioxide is an important basic bulk raw material for industrial production. Its crystal structure is γ-MnO2. It has the characteristics of high purity, good crystal form, and excellent electrochemical activity. It is one of the main raw materials for alkaline manganese batteries. The preparation process of electrolytic manganese dioxide mainly includes five stages: leaching, impurity removal, electrolysis, stripping and crushing, and drying. Among them, with the long cycle of the electrolysis process, the calcium and magnesium content in the electrolyte gradually increases until calcium sulfate and magnesium sulfate reach saturation, resulting in increased electrolysis costs and reduced product quality. In actual production, high calcium and magnesium electrolytes are usually reused as electrolytic manganese dioxide tail liquids for front-end leaching. However, this will cause a large amount of manganese sulfate to enter the water-containing manganese slag and be lost, resulting in a waste of manganese resources. Therefore, how to convert electrolytic manganese dioxide tail liquid into high value-added products is the key to improving efficiency and energy saving in the electrolytic manganese dioxide industry.

[0003] As a high-performance structural material, manganese trioxide is used to prepare spinel lithium manganese oxide with high specific capacity and good cycle stability. In recent years, with the rise of strategic industries such as high-end equipment manufacturing, new energy vehicles, and new materials, the requirements for the output and quality of manganese trioxide have become higher. Manganese trioxide is mainly produced by calcining manganese carbonate, and the calcium and magnesium impurities in manganese carbonate affect the product quality of manganese trioxide.

[0004] In summary, the present invention uses electrolytic manganese dioxide tail liquid as raw material, adopts ammonium bicarbonate and ammonium sulfite as manganese precipitants, and uses composite manganese salt as intermediate product. The calcium and magnesium impurities undergo multiple phase changes to achieve deep impurity removal of calcium and magnesium, and finally obtain battery-grade sponge-like manganese trioxide. Summary of the invention

[0005] In view of the technical problems of raw materials and application limitations in the existing manganese trioxide preparation process, the present invention provides a method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid, using ammonium bicarbonate and ammonium sulfite as manganese mixed precipitants and composite manganese salt as intermediate materials, so that calcium and magnesium impurities undergo multiple phase changes to achieve deep impurity removal of calcium and magnesium. The prepared manganese trioxide is a battery-grade sponge-like material with rich pore structure, stable tap density and specific surface area, and is an excellent raw material for high-performance new energy batteries. The process flow is short and green and environmentally friendly.

[0006] The specific technical solutions of the present invention are as follows:

[0007] A method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid comprises the following steps:

[0008] S1. The pH of the electrolytic manganese dioxide tail liquid is adjusted to obtain a manganese sulfate mother liquor, and ammonium bicarbonate and ammonium sulfite are dissolved in water to prepare a manganese precipitant;

[0009] S2. A manganese precipitant is introduced into the manganese sulfate mother liquor obtained in S1, and the mixture is stirred continuously at a constant temperature. After sufficient reaction, solid-liquid separation is performed, and the solid phase product is dried to obtain a composite manganese salt;

[0010] S3. The composite manganese salt obtained in S2 was calcined and cooled to obtain impurity-containing manganese trioxide;

[0011] S4. The impurity-containing manganese trioxide obtained in S3 is ultrasonically washed, and battery-grade sponge-like manganese trioxide is obtained after solid-liquid separation and drying.

[0012] Furthermore, in S1, the pH value of the electrolytic manganese dioxide tail liquid is adjusted to 6.5-7; the concentration of ammonium bicarbonate in the manganese precipitant is 8.0%-12.0%, and the concentration of ammonium sulfite is 1.5%-4.0%.

[0013] Furthermore, in S2, the input amount of manganese precipitant is 1.05~1.2 times the theoretical value (the theoretical value is the amount of manganese precipitant required for the complete reaction of manganese dioxide), the stirring rate is 500~800r / min, the reaction temperature is 40~60℃, the reaction time is 1.5~2h, the drying temperature of the solid phase product is 60~120℃, and the drying time is 6~8h.

[0014] Furthermore, in S3, the calcination temperature is 550-600°C, and the calcination time is 4-6h; the calcination is carried out in a rotary furnace, and the furnace rotation rate is 5-15r / min; the calcination heating rate is 5-10°C / min.

[0015] Furthermore, in the ultrasonic washing in S4, deionized water is used as a detergent, a solid-liquid mass ratio of 0.5-1, an ultrasonic frequency of 40-60 KHz, and an ultrasonic time of 30-90 min; the drying temperature of the filter cake is 120-180° C., and the drying time is 6-8 h.

[0016] To further illustrate the basic principle of the present invention, the main chemical reaction formulas involved are as follows:

[0017] Precipitation reaction:

[0018]

[0019] High temperature calcination:

[0020]

[0021] Ultrasonic cleaning:

[0022]

[0023] The material relationship in the present invention is as follows:

[0024]

[0025] k—is the material addition coefficient, and 1 is the theoretical value;

[0026] C1—ammonium bicarbonate concentration, %;

[0027] C2—ammonium sulfite concentration, %;

[0028] C3—manganese sulfate concentration, %;

[0029] V1—the amount of manganese precipitant added, L;

[0030] V2—Amount of manganese sulfate added, L.

[0031] The present invention uses ammonium bicarbonate and ammonium sulfite as manganese precipitants, and manganese sulfite as one of the components of the composite manganese salt as an intermediate product for calcium and magnesium impurity removal, and converts the sulfite into a soluble sulfate by calcining, which not only does not cause the environmental risk of sulfite as a secondary carcinogen, but also significantly improves the effect of calcium and magnesium impurity removal, thereby ultimately greatly reducing the environmental risk. Compared with the existing calcium and magnesium impurity removal mainly using fluoride salt precipitation, phosphate precipitation and recrystallization methods (the former two will produce hazardous waste, and the latter has huge energy consumption costs), it has very obvious advantages.

[0032] The beneficial effects of the present invention are:

[0033] (1) The present invention uses ammonium bicarbonate and ammonium sulfite as manganese precipitants, and composite manganese salt as an intermediate product, and the calcium and magnesium impurities undergo multiple phase changes to achieve deep impurity removal of calcium and magnesium;

[0034] (2) The impurity removal process of the present invention does not generate new pollutants, has a short process flow, is low-cost, and has great industrial potential;

[0035] (3) The battery-grade sponge-like manganese trioxide prepared by the present invention has a rich pore structure, stable tap density and specific surface area, and is an excellent material for high-performance new energy batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The process flow chart of the method of the present invention is shown in FIG.

[0037] Figure 2The equipment flow chart of the method of the present invention is as follows: 1. ammonium sulfite stirring tank, 2. ammonium bicarbonate stirring tank, 3. reaction kettle, 4. filter press I, 5. rotary atmosphere pyrolysis furnace, 6. ultrasonic instrument, 7. filter press II, 8. electrolytic manganese dioxide tail liquid, 9. composite manganese salt I, 10. composite manganese salt II, 11. battery-grade sponge-like manganese trioxide, 12. filtrate I, 13. filtrate II.

[0038] Figure 3 This is the X-ray diffraction spectrum of manganese trioxide obtained in Example 1.

[0039] Figure 4 This is a scanning electron microscope spectrum of the manganese trioxide obtained in Example 1. DETAILED DESCRIPTION

[0040] In order to better explain the content of the present invention, the present invention is further described in detail below in combination with embodiments and comparative examples, but the present invention is not limited thereto.

[0041] like Figure 1 and Figure 2 As shown, the electrolytic manganese dioxide tail liquid 8 is input into the reactor 3 after adjusting the pH, the ammonium sulfite solution in the ammonium sulfite stirring tank 1 and the ammonium bicarbonate solution in the ammonium bicarbonate stirring tank 2 are mixed to form a manganese precipitant, and then input into the reactor 3 to react with the electrolytic manganese dioxide tail liquid 8 in the reactor 3, the mixed solution after the reaction is filtered by the filter press I 4, the filtrate is the filtrate I 12, the filter residue is the composite manganese salt I 9, the composite manganese salt I 9 is dried to obtain the composite manganese salt II 10, the composite manganese salt II 10 is subjected to rotary calcination in a rotary atmosphere pyrolysis furnace 5 to obtain impurity-containing manganese trioxide, and then ultrasonic washing is carried out in an ultrasonicator 6, the washing liquid is filtered by the filter press II 7, the filtrate is the filtrate II 13, and the filter residue is the battery-grade sponge-like manganese trioxide 11. Example 1

[0042] Take 12L of electrolytic manganese dioxide tail liquid (wherein the contents of manganese, calcium and magnesium are shown in Table 1) in a reactor, adjust the pH to 7.0 with dilute ammonia water to prepare manganese sulfate mother liquor. Take 0.9kg of ammonium bicarbonate and 0.15kg of ammonium sulfite monohydrate and deionized water to prepare 10L of manganese precipitant, and the amount of manganese precipitant added is 1.1 times the theoretical value.

[0043] Table 1 Manganese, calcium and magnesium content in electrolytic manganese dioxide tail liquid

[0044]

[0045] Then, the manganese precipitant was continuously input into the manganese sulfate mother liquor at an input rate of 0.2 L / min, a reaction stirring rate of 600 r / min, a reaction temperature of 50°C, and a reaction time of 2 h. After the reaction was completed, a filter press operation was performed, and the filter cake was dried at 60°C for 6 h to obtain 0.82 kg of composite manganese salt.

[0046] The composite manganese salt was placed in a rotary atmosphere calcining furnace, the heating rate was controlled at 5°C / min, the calcination temperature was 550°C, the calcination time was 6h, the rotation frequency was set at 5r / min, and after cooling, 0.59kg of impurity-containing manganese trioxide was obtained.

[0047] The impurity-containing manganese trioxide and deionized water were mixed into a slurry with a solid-liquid mass ratio of 0.5, and then placed in an ultrasonic instrument with an ultrasonic frequency of 60KHz, a stirring rate of 100r / min, and an ultrasonic time of 30min. After the end, the filter was pressed and the filter cake was dried at 150°C for 6h to obtain 0.43kg of battery-grade sponge manganese trioxide. The tap density was tested to be 1.65g / cm 3 .

[0048] The battery-grade sponge-like manganese trioxide was subjected to ICP test. The test results are shown in Table 2. Meanwhile, its XRD and SEM characterization results are shown in Figure 3 and Figure 4 .

[0049] Table 2 ICP test results of battery-grade sponge manganese trioxide

[0050] Comparative Example 1

[0051] The difference from Example 1 is that only ammonium bicarbonate is used in the precipitant, and ammonium sulfite is not included.

[0052] Take 12L of electrolytic manganese dioxide tail liquid (wherein the contents of manganese, calcium and magnesium are shown in Table 1) in a reactor, adjust the pH to 7.0 with dilute ammonia water to prepare manganese sulfate mother liquor. Take 1.2kg of ammonium bicarbonate and deionized water to prepare 10L of manganese precipitant, and the amount of manganese precipitant added is 1.1 times the theoretical value.

[0053] Then, the manganese precipitant was continuously input into the manganese sulfate mother liquor at an input rate of 0.2 L / min, a stirring rate of 600 r / min, a reaction temperature of 50° C., and a reaction time of 2 h. After the reaction was completed, a filter press operation was performed, and the filter cake was dried at 60° C. for 6 h to obtain 0.78 kg of manganese carbonate.

[0054] Manganese carbonate was placed in a rotary atmosphere calcining furnace, the heating rate was controlled to be 5°C / min, the calcination temperature was 550°C, the calcination time was 6h, the rotation frequency was set to 5r / min, and after cooling, 0.53kg of impurity-containing manganese trioxide was obtained.

[0055] The impurity-containing manganese trioxide and deionized water were mixed into a slurry with a solid-liquid mass ratio of 0.5, and then placed in an ultrasonic instrument with an ultrasonic frequency of 60KHz, a stirring rate of 100r / min, and an ultrasonic time of 30min. After the end, the filter was pressed and the filter cake was dried at 150°C for 6h to obtain 0.53kg of manganese trioxide, with a tap density of 1.59g / cm 3 , and its manganese, calcium and magnesium contents are shown in Table 3.

[0056] Table 3 ICP test results of manganese trioxide in comparative example 1

[0057]

[0058] By comparing the test results in Table 2 and Table 3, it can be seen that the present invention uses ammonium bicarbonate and ammonium sulfite as manganese precipitants, which significantly reduces the content of calcium and magnesium impurities, thereby significantly improving the purity of the obtained manganese trioxide. Comparative Example 2

[0059] The difference from Example 1 is that the content of ammonium sulfite in the precipitant is higher.

[0060] Take 12L of electrolytic manganese dioxide tail liquid (wherein the contents of manganese, calcium and magnesium are shown in Table 1) in a reactor, adjust the pH to 7.0 with dilute ammonia water to prepare manganese sulfate mother liquor. Take 0.5kg of ammonium bicarbonate and 0.5kg of ammonium sulfite monohydrate and deionized water to prepare 10L of manganese precipitant, and the amount of manganese precipitant added is 1.1 times the theoretical value.

[0061] Then, the manganese precipitant was continuously input into the manganese sulfate mother liquor at an input rate of 0.2 L / min, a reaction stirring rate of 600 r / min, a reaction temperature of 50°C, and a reaction time of 2 h. After the reaction was completed, a filter press operation was performed, and the filter cake was dried at 60°C for 6 h to obtain 0.84 kg of composite manganese salt.

[0062] The composite manganese salt was placed in a rotary atmosphere calcining furnace, the heating rate was controlled at 5°C / min, the calcination temperature was 550°C, the calcination time was 6h, the rotation frequency was set at 5r / min, and after cooling, 0.63kg of impurity-containing manganese trioxide was obtained.

[0063] The impurity-containing manganese trioxide and deionized water were mixed into a slurry with a solid-liquid mass ratio of 0.5, and then placed in an ultrasonic instrument with an ultrasonic frequency of 60KHz, a stirring rate of 100r / min, and an ultrasonic time of 30min. After the end, the filter was pressed and the filter cake was dried at 150°C for 6h to obtain 0.24kg of battery-grade sponge manganese trioxide with a tap density of 1.59g / cm 3 .

[0064] The battery-grade sponge manganese trioxide was subjected to ICP test, and the test results are shown in Table 4.

[0065] Table 4 ICP test results of battery-grade sponge manganese trioxide

[0066]

[0067] By comparing the test results in Table 4 and Table 2, it can be seen that the calcium and magnesium contents in the battery-grade sponge-like manganese trioxide prepared by the precipitant with high ammonium sulfite content are basically the same, but the output is significantly reduced. Example 2

[0068] This example is an enlarged experiment of Example 1.

[0069] Take 40L of electrolytic manganese dioxide tail liquid (wherein the contents of manganese, calcium and magnesium are shown in Table 1) in a reactor, adjust the pH to 7.0 with dilute ammonia water to prepare manganese sulfate mother liquor. Take 3kg of ammonium bicarbonate and 0.5kg of ammonium sulfite and deionized water to prepare 30L of manganese precipitant, and the amount of manganese precipitant added is 1.1 times the theoretical value.

[0070] Then, the manganese precipitant was continuously input into the manganese sulfate mother liquor at an input rate of 0.8 L / min, a reaction stirring rate of 600 r / min, a reaction temperature of 50°C, and a reaction time of 2 h. After the reaction was completed, a filter press operation was performed, and the filter cake was dried at 60°C for 6 h to obtain 2.86 kg of composite manganese salt.

[0071] The composite manganese salt was placed in a rotary atmosphere calcining furnace, the heating rate was controlled at 5°C / min, the calcination temperature was 550°C, the calcination time was 6h, the rotation frequency was set at 5r / min, and after cooling, 2.07kg of impurity-containing manganese trioxide was obtained.

[0072] The impurity-containing manganese trioxide and deionized water were mixed into a slurry with a solid-liquid mass ratio of 0.5, and then placed in an ultrasonic instrument with an ultrasonic frequency of 60KHz, a stirring rate of 100r / min, and an ultrasonic time of 30min. After the end, the filter was pressed and the filter cake was dried at 150°C for 6h to obtain 1.45kg of battery-grade sponge manganese trioxide with a tap density of 1.66g / cm 3 .

[0073] The battery-grade sponge manganese trioxide was subjected to an ICP test. The test results are shown in Table 5.

[0074] Table 5 ICP test results of battery-grade sponge manganese trioxide

[0075]

[0076] The test results in Table 5 show that the present invention still maintains good calcium and magnesium removal capabilities in the scale-up experiment and has great industrial application potential.

Claims

1. A method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid, characterized in that: The steps include: S1. The pH of the electrolytic manganese dioxide tail liquid is adjusted to obtain a manganese sulfate mother liquor, and ammonium bicarbonate and ammonium sulfite are dissolved in water to prepare a manganese precipitant; S2. A manganese precipitant is introduced into the manganese sulfate mother liquor obtained in S1, and the mixture is stirred continuously at a constant temperature. After sufficient reaction, solid-liquid separation is performed, and the solid phase product is dried to obtain a composite manganese salt; S3. The composite manganese salt obtained in S2 was calcined and cooled to obtain impurity-containing manganese trioxide; S4. The impurity-containing manganese trioxide obtained in S3 is ultrasonically washed, and battery-grade sponge-like manganese trioxide is obtained after solid-liquid separation and drying.

2. The method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid according to claim 1, characterized in that: In S1, the concentration of ammonium bicarbonate in the manganese precipitant is 8.0%~12.0%, and the concentration of ammonium sulfite is 1.5%~4.0%.

3. The method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid according to claim 1, characterized in that: In S1, the pH of the manganese sulfate mother liquor is adjusted to 6.5-7.

4. The method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid according to claim 1, characterized in that: In S2, the input amount of manganese precipitant is 1.05~1.2 times the theoretical value.

5. The method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid according to claim 1, characterized in that: In S2, the stirring rate is 500~800r / min, the reaction temperature is 40~60℃, the reaction time is 1.5~2h, the drying temperature of the solid phase product is 60~120℃, and the drying time is 6~8h.

6. The method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid according to claim 1, characterized in that: In S3, the calcination temperature is 550~600℃, and the calcination time is 4~6h.

7. The method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid according to claim 1, characterized in that: In S3, calcination is carried out in a rotary furnace, and the furnace rotation rate is 5~15r / min; the calcination heating rate is 5~10℃ / min.

8. The method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid according to claim 1, characterized in that: The ultrasonic washing in S4 uses deionized water as a detergent, a solid-liquid mass ratio of 0.5 to 1, an ultrasonic frequency of 40 to 60 kHz, and an ultrasonic time of 30 to 90 minutes.

9. The method for preparing battery-grade sponge-like manganese trioxide from electrolytic manganese dioxide tail liquid according to claim 1, characterized in that: In S4, the drying temperature of the filter cake is 120-180°C, and the drying time is 6-8h.

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