Method for producing manganese zinc ferrite

Abstract

A method for producing manganese zinc ferrite, the method comprising: crushing waste dry batteries including at least one of an alkali manganese dry battery and a manganese dry battery; sieving a crushed product of the waste dry batteries to obtain fine particles each having a maximum particle diameter of 1 mm or less; generating an aqueous solution in which the fine particles are dissolved with an acid; and adding an alkali aqueous solution to the aqueous solution to set the pH to 10 or higher to precipitate an iron compound containing manganese and zinc.

Description

Method for manufacturing manganese zinc ferrite

[0001] The present disclosure relates to a method for manufacturing manganese zinc ferrite.

[0002] As global environmental problems become more serious, the collection rate of manganese dry batteries and the like that are consumed in large quantities is only about a few percent, and it is difficult to say that the effective utilization and recycling of used dry batteries are being sufficiently carried out. In addition, when recycling dry batteries, it is necessary to melt them at high temperatures, which not only discharges a large amount of carbon dioxide but also consumes a large amount of electricity. Furthermore, manganese (Mn), zinc (Zn), iron (Fe), etc. contained in dry batteries must be separated by magnetic separation or the like, and a great deal of labor is required for recycling waste dry batteries.

[0003] Japanese Patent Application Laid-Open No. 9-156929

[0004] Manuel F. Almeida, et al., “Characterization of spent AA household alkaline batteries”, Waste Management, Volume 26, Issue 5, 2006, Pages 466-476Fei Hua, et al., “Direct Preparation of the Nanocrystalline MnZn Ferrites by Using Oxalate as Precipitant”, Journal of Materials Science and Chemical Engineering Vol.03 No.12(2015), Article ID:61955, 7 pagesW. Shatti, et al., “Co-precipitation method for the preparation of Mn-Zn Ferrite and study their Structural and Magnetic properties”, Journal of Ovonic Research, June 2022, 18(4):473-479

[0005] One embodiment aims to provide a method for producing manganese zinc ferrite that does not require high-temperature melting and allows for the simple and inexpensive recycling of waste dry cell batteries.

[0006] The method for producing manganese zinc ferrite in this embodiment involves crushing a waste dry cell containing at least one of an alkaline manganese dry cell and a manganese dry cell, sieving the crushed waste dry cell material to obtain fine particles with a maximum diameter of 1 mm or less, dissolving the fine particles in an acid to produce an aqueous solution, adding sodium hydroxide to the aqueous solution to make the pH 10 or higher, and precipitating an iron compound containing manganese and zinc.

[0007] According to the manganese zinc ferrite manufacturing method of this embodiment, waste dry cell batteries can be recycled simply and inexpensively without requiring high-temperature melting.

[0008] Figure 1 is a schematic diagram showing an example of the configuration of a crusher according to the embodiment. Figure 2 is a graph showing the phase identification results of precipitates obtained by XRD analysis using the sample according to the example as raw material. Figure 3 is a graph showing the phase identification results of precipitates obtained by XRD analysis using the sample according to the example as raw material.

[0009] The inventors have discovered a method for collecting alkaline manganese dry cell batteries and manganese dry cell batteries, etc., and recycling them by producing high-quality manganese zinc ferrite from waste dry cell batteries without high-temperature melting or other processes. This method is described in detail below. The method for producing manganese zinc ferrite described below can be utilized as a recycling method for waste dry cell batteries.

[0010] (Collected waste dry cell batteries) In order to produce manganese zinc ferrite, manganese dry cell batteries and alkaline manganese dry cell batteries containing raw materials such as manganese, zinc, and iron are collected. Both of these dry cell batteries contain manganese in the positive electrode and zinc in the negative electrode. The outer casing of alkaline manganese dry cell batteries is mainly made of steel. The outer casing of manganese dry cell batteries may also be made of zinc, but some manganese dry cell batteries use steel for the outer casing, similar to alkaline manganese dry cell batteries.

[0011] The inventors propose utilizing existing logistics networks for the collection of these dry cell batteries. As an example, they envision applying a collaborative logistics system that delivers packages via courier to general households, company offices, factories, etc., and collecting used dry cell batteries from these delivery locations on the return journey. They believe that by providing incentives such as awarding points, providers of used dry cell batteries will be encouraged to dispose of them when receiving packages via courier, thereby establishing a permanent collection system.

[0012] (Crushing of waste dry cell batteries) Next, the collected waste dry cell batteries are crushed using a crusher. For example, a twin-screw crusher can be used as the crusher. Figure 1 shows an example of a twin-screw crusher.

[0013] Figure 1 is a schematic diagram showing an example of the configuration of a crusher 10 according to an embodiment. More specifically, Figure 1(a) is a top view of the crusher 10, and Figure 1(b) is a cross-sectional view of the crusher 10 viewed from the side.

[0014] In one embodiment, the crusher 10 is configured as a twin-screw crusher equipped with two screw rotors 15.

[0015] As shown in Figure 1, the crusher 10 of this embodiment includes a hopper 11, a crushing chamber 12, a sieve 13, and a recovery container 14.

[0016] The hopper 11 is the input port for the waste dry cell batteries C, which are to be crushed, and is located at the top of the crusher 10. The crushing chamber 12 is located below the hopper 11 and is equipped with, for example, two screw rotors 15. These screw rotors 15 have shafts on which screw blades are attached, and as the screw rotors 15 rotate around these shafts, the waste dry cell batteries C that have been fed from the hopper 11 into the crushing chamber 12 are crushed. The recovery container 14 is located below the crushing chamber 12 via a sieve 13 and contains the waste dry cell batteries C that have passed through the sieve 13 and become fine particles Pf.

[0017] The mesh of the sieve 13, that is, the holes (not shown) in the sieve, preferably have a diameter of 1 mm or less. This allows the mixed particles Pc, which contain particles larger than 1 mm in diameter immediately after crushing by the screw rotor 15, to be separated by the sieve 13, resulting in fine particles Pf consisting of particles with a diameter of 1 mm or less. Furthermore, by repeatedly crushing the mixed particles Pc that remain in the crushing chamber 12 without passing through the sieve 13 to further refine them, even finer particles Pf can be obtained.

[0018] More specifically, the particle size of the fine particles Pf is between 0.3 mm and 1.0 mm. Since the fine particles Pf are particles that have passed through the sieve 13 having sieve holes with a diameter of 1 mm, the particle size of the fine particles Pf described here is the maximum diameter of each individual particle.

[0019] Thus, by using fine particles Pf obtained by crushing waste dry cell batteries C into fine particles as a raw material, the dissolution of the raw material, which will be described in detail later, becomes easier, and high-quality manganese zinc ferrite can be obtained.

[0020] Here, the iron mainly contained in the casing of the waste dry cell C is difficult to crush. Also, the crushed mixed particles Pc tend to adhere to the side walls of the crushing chamber 12 due to the effects of the electrolyte in the waste dry cell C and the humidity in the environment where the crusher 10 is placed. As for the electrolyte, if the waste dry cell C is an alkaline manganese dry cell, for example, an alkali metal hydroxide such as potassium hydroxide is used, and if it is a manganese dry cell, for example, zinc chloride is used. These electrolytes act as binders, and the mixed particles Pc, fine particles Pf, and other crushed materials may gather around the relatively large crushed material, iron, making it difficult for them to pass through the sieve 13.

[0021] Therefore, when the remaining charge of the waste dry cell battery C is zero, that is, when the waste dry cell battery C is completely discharged, it is preferable to crush the waste dry cell battery C in a low-humidity environment. It is also effective to supply air to the crushing chamber 12 using a supply mechanism (not shown) and perform crushing in a dry state inside the crushing chamber 12. However, even in this case, due to the difficulty in crushing described above, the iron content ratio in the fine particles Pf tends to be lower compared to the mixed particles Pc.

[0022] On the other hand, if the remaining charge of the collected waste dry cell batteries C is not zero, wet crushing can also be performed. In this case, for example, water can be sprayed onto the hopper 11.

[0023] Furthermore, the crushing of waste dry cell batteries C is not limited to the twin-screw crusher described above; various crushers can be used as long as they can crush the waste dry cell batteries C into fine particles Pf with a particle size of 1 mm or less. Examples of such crushers include impact crushers, which crush the object by impacting it with an impact plate.

[0024] (Component analysis of fine particles) From the fine particles Pf obtained as described above, manganese zinc ferrite is produced through various wet processes, as will be detailed later. In fine particles Pf obtained from randomly collected waste dry cell batteries, the component ratios of manganese, zinc, and iron vary from time to time.

[0025] Therefore, in manufacturing manganese zinc ferrite, the components of the obtained fine particle Pf are first analyzed, for example, by X-ray fluorescence (XRF) analysis.

[0026] (Leaching of fine particles) Next, the required amount of hydrochloric acid is calculated based on the above analysis results, and the required amount of 2 moles / liter hydrochloric acid is added to the fine particles Pf mentioned above, and stirred for 60 minutes at a temperature of, for example, 50°C. Since hydrochloric acid is a monoprotic acid, the number of moles required for the above reaction is 2 to 4 moles per mole of manganese, zinc, or iron.

[0027] As a result, the manganese, zinc, and iron in the fine particles Pf dissolve and react with hydrochloric acid to obtain an aqueous chloride solution of manganese, zinc, and iron.

[0028] Afterward, the chloride solution is filtered to remove the residue.

[0029] (Adjustment of component ratio) As described above, the component ratios of manganese, zinc, and iron in the fine particles Pf obtained from crushed waste dry cell batteries vary from time to time. Furthermore, among these, iron in waste dry cell batteries is difficult to crush, and relatively large iron fragments agglomerate with other fragments, so the iron component ratio in the fine particles Pf after passing through sieve 13 tends to be lower compared to the mixed particles Pc that did not pass through sieve 13.

[0030] On the other hand, manganese zinc ferrite, which is often used in magnetic heads and transformers and is said to have desirable magnetic properties, is composed of 50-55 mol% Fe2O3, 20-30 mol% MnO, and 15-30 mol% ZnO.

[0031] Therefore, to the aqueous solution of chloride obtained as described above, iron(III) chloride (FeCl) is added to achieve a preferred component ratio for manganese zinc ferrite. ３ Add ) at this time Fe to the total number of moles of MnO and ZnO ２ O ３ The amount of iron(III) chloride added is adjusted so that the molar ratio of (MnO + ZnO):Fe ２ O ３ The amount of iron(III) chloride needed to achieve a 1:1 ratio is, for example, about 1.12 times, more preferably 2 times or more, the weight of the fine particles Pf obtained by crushing. Adding about 1.12 times the amount of iron(III) chloride yields manganese-rich manganese zinc ferrite, and adding 2 times or more the amount of iron(III) chloride yields manganese zinc ferrite with better crystallinity.

[0032] (Formation of manganese zinc ferrite) Next, the aqueous solution of the chloride to which iron(III) chloride has been added is heated to 50°C or higher, and an alkaline aqueous solution is added until the pH of the chloride aqueous solution reaches 10 or higher, and the mixture is stirred until a precipitate forms. As the alkaline aqueous solution, for example, an aqueous solution of pure sodium hydroxide (NaOH) can be used. Pure sodium hydroxide is sodium hydroxide with a purity of 98% or higher. Heating and stirring for at least 30 minutes is required for a precipitate to form in the aqueous solution.

[0033] In this way, by making the chloride aqueous solution alkaline, the manganese, zinc, and iron that were ionized and dissolved in the aqueous solution precipitate as a manganese-zinc-iron compound. By filtering, washing, and drying the precipitate that has been formed, powdered manganese-zinc ferrite can be obtained.

[0034] Based on the above, the manganese zinc ferrite of the embodiment is manufactured.

[0035] Furthermore, in the aforementioned leaching treatment of fine Pf particles, it is also possible to use 2 moles / liter sulfuric acid instead of 2 moles / liter hydrochloric acid. When using sulfuric acid, which is a divalent acid, the number of moles required for the above reaction is 1 to 2 moles per mole of manganese, zinc, or iron. Also, when adjusting the components in sulfuric acid, since manganese, zinc, and iron are in the form of sulfate ions, iron(III) sulfate (Fe) can be used instead of iron(III) chloride. ２ (SO ４ ) ３ ) can be added. Furthermore, it is also possible to use nitric acid instead of hydrochloric acid in the leaching process and to use nitrate compounds to adjust its composition.

[0036] (Summary) As global environmental problems worsen, various companies and organizations are undertaking various initiatives, but there is still no magic bullet for reducing carbon dioxide emissions. In this situation, there is a demand for the effective use and recycling of resources from the rapidly increasing amount of industrial waste. However, the collection rate for alkaline manganese dry cell batteries and manganese dry cell batteries, which are consumed in large quantities, remains at only a few percent. Furthermore, used or discarded dry cell batteries are melted at high temperatures, and the contained materials such as manganese, zinc, and iron are separated by magnetic separation or other methods.

[0037] Thus, dry smelting recycling methods involving high-temperature melting emit large amounts of carbon dioxide and consume a great deal of electricity. Furthermore, magnetic separation of the molten material requires considerable labor. For these reasons, it would be extremely beneficial to reuse waste dry cell batteries using a simple and inexpensive method that does not involve high-temperature processing and does not require material separation such as magnetic separation.

[0038] On the other hand, in recent years, manganese zinc ferrite has attracted attention for use as a magnetic head or transformer. For general applications, manganese zinc ferrite can be used as a filler for building materials such as bricks, tiles, and concrete blocks, and can also be used for disaster prevention applications such as temperature-sensitive switches and radio wave absorbers by utilizing its excellent magnetic properties. In addition, recent research has also reported papers stating that ferrite-containing materials are effective as radiation shielding materials.

[0039] To produce a manganese zinc ferrite mass, commercially available powder raw materials are purchased, weighed, and mixed. In the case of the wet method, a drying process is included here, and then, both the wet method and the dry method go through common processes. That is, pre-firing, pulverization, granulation, molding, further firing, and finally processing and inspection are carried out to complete the process.

[0040] According to the method for producing manganese zinc ferrite of the embodiment, the mixed particles Pc, which are crushed products of waste dry batteries, are sieved by a sieve 13 to obtain fine particles Pf with a maximum diameter of each particle of 1 mm or less. An aqueous solution in which the fine particles Pf are dissolved by an acid is generated, an alkaline aqueous solution is added to the aqueous solution to make the pH 10 or more, and an iron compound containing manganese and zinc is precipitated.

[0041] As a result, it is possible to recycle waste dry batteries simply and at low cost without requiring high-temperature melting. In addition, the raw materials obtained from waste dry batteries can be easily diverted to manganese zinc ferrite by a simple operation as described above. Therefore, it is very beneficial in terms of manufacturing cost, safety, and operability compared to conventional dry metallurgical and powder metallurgical methods that require high-temperature heating.

[0042] The manganese zinc ferrite produced in this way is in the form of a powder having good crystals and can be utilized as a magnetic head, transformer, or for disaster prevention applications such as temperature-sensitive switches and radio wave absorbers, and further as a radiation shielding material, etc.

[0043] According to the method for producing manganese zinc ferrite of the embodiment, an iron (III) salt is added to the aqueous solution in which the fine particles Pf are dissolved, and in the aqueous solution, the total number of moles of manganese (II) and zinc (II) and the number of moles of iron (III) are adjusted so that the ratio becomes 1:1. As a result, a powder of manganese zinc ferrite having preferable magnetic characteristics can be obtained.

[0044] (Modified Example) In the above-described embodiment, the manganese zinc ferrite is produced using the fine particles Pf obtained by crushing the waste dry battery and passing through the sieve 13 as a raw material. As a result, a powder of manganese zinc ferrite having a good crystal structure can be obtained.

[0045] However, it is also possible to produce manganese zinc ferrite using the mixed particles Pc containing particles having a particle diameter exceeding 1 mm and not passing through the sieve 13 as a raw material. More specifically, the mixed particles Pc in which the maximum diameter of each particle exceeds 1 mm and is 10 mm or less can be used for producing manganese zinc ferrite.

[0046] As described above, since iron in the waste dry battery is difficult to be crushed and aggregates with other crushed materials, the mixed particles Pc contain more iron than the fine particles Pf that have passed through the sieve 13. Therefore, the amount of iron (III) chloride or the like required for component adjustment can be reduced, and it is suitable for the production of manganese zinc ferrite for applications that do not require high characteristics. Specifically, the amount of iron (III) chloride required for component adjustment is only about half the weight of the mixed particles Pc as a raw material.

[0047] According to the method for producing manganese zinc ferrite of the modified example, an aqueous solution in which the mixed particles Pc containing particles having a maximum diameter exceeding 1 mm before being applied to the sieve 13 are dissolved by an acid is generated, an alkaline aqueous solution is added to the aqueous solution to make the pH 10 or more, and an iron compound containing manganese and zinc is precipitated. As a result, powdery manganese zinc ferrite for low grade can be produced at a lower cost. In addition, the recycling rate of resources contained in the waste dry battery can be further improved.

[0048] Hereinafter, the results of the production experiment of manganese zinc ferrite powder based on the production methods of the above-described embodiment and modified example will be described.

[0049] The collected waste dry cell batteries were crushed using a twin-screw crusher to obtain sample S1 before sieving and sample S2 after sieving. Sample S1 contained particles with a maximum particle size exceeding 1 mm, while sample S2 contained particles with a maximum particle size of 1 mm or less. Furthermore, component analysis of these samples S1 and S2 was performed by XRF analysis, and the results shown in Table 1 below were obtained.

[0050]

[0051] As shown in Table 1, sample S1, which did not pass through the sieve, showed a higher iron content compared to sample S2, which passed through the sieve.

[0052] Next, samples S1 and S2 were subjected to leaching treatment with hydrochloric acid. Based on the above analysis results, 22.6 mL of 2 mol / liter hydrochloric acid was added to 1 g of sample S1, and 36.4 mL of 2 mol / liter hydrochloric acid was added to 1 g of sample S2. The mixture was then heated to 50°C and stirred at 450 revolutions per minute for 60 minutes.

[0053] Next, iron(III) chloride was added to the hydrochloric acid of samples S1 and S2 to adjust the composition. Based on the above analysis results, 0.55 g of iron(III) chloride was added to the hydrochloric acid of sample S1 per gram of sample S1, and 1.17 g of iron(III) chloride was added to the hydrochloric acid of sample S2 per gram of sample S2.

[0054] Next, aqueous solutions of the chlorides from the adjusted samples S1 and S2 were heated to 50°C, and pure sodium hydroxide was added until the pH of each aqueous solution reached 10 or higher. Then, the mixture was stirred for 30 minutes while maintaining the temperature at 50°C until a precipitate formed.

[0055] The precipitated material was filtered, washed, and dried, and then the crystalline phase was identified using X-ray diffraction (XRD) analysis, yielding the results shown in Figures 2 and 3.

[0056] Figure 2 is a graph showing the phase identification results of precipitates obtained by XRD analysis of sample S1 used as the raw material in the example. Figure 3 is a graph showing the phase identification results of precipitates obtained by XRD analysis of sample S2 used as the raw material in the example. In the graphs of Figures 2 and 3, the horizontal axis is the diffraction angle and the vertical axis is the integrated intensity.

[0057] As shown in Figures 2 and 3, it can be seen that manganese zinc ferrite composed of a single spinel phase suitable as a magnetic material is produced regardless of whether sample S1 or S2 is used as the raw material. Furthermore, a sharper peak is detected in Figure 3, based on sample S2, compared to Figure 2, based on sample S1, indicating that a higher quality crystal was obtained.

[0058] 10 Crusher 11 Hopper 12 Crushing chamber 13 Sieve 14 Collection container C Waste dry cell battery Pc Mixed particles Pf Fine particles

Claims

1. A method for producing manganese zinc ferrite, comprising: crushing a used dry cell containing at least one of an alkaline manganese dry cell and a manganese dry cell; sieving the crushed material of the used dry cell to obtain fine particles with a maximum diameter of 1 mm or less; producing an aqueous solution by dissolving the fine particles in an acid; adding an alkaline aqueous solution to the aqueous solution to make the pH 10 or higher; and precipitating an iron compound containing manganese and zinc.

2. The method for producing manganese zinc ferrite according to claim 1, wherein, before adding the alkaline aqueous solution, an iron(III) salt is added to the aqueous solution in which the fine particles are dissolved with an acid, and the composition is adjusted so that the ratio of the total number of moles of manganese and zinc to the number of moles of iron in the aqueous solution is 1:

1.

3. The method for producing manganese zinc ferrite according to claim 2, wherein the acid used to dissolve the fine particles is 2 moles / liter hydrochloric acid, and the iron(III) salt used to adjust the components of the aqueous solution is iron(III) chloride.

4. The method for producing manganese zinc ferrite according to claim 2, wherein the acid used to dissolve the fine particles is 2 moles / liter sulfuric acid, and the iron(III) salt used to adjust the components of the aqueous solution is iron(III) sulfate.

5. The method for producing manganese zinc ferrite according to claim 2, wherein the acid used to dissolve the fine particles is 2 moles / liter nitric acid, and the iron(III) salt used to adjust the components of the aqueous solution is iron(III) nitrate.

6. A method for producing manganese zinc ferrite according to claim 1, comprising: dissolving the crushed material containing particles with a maximum diameter exceeding 1 mm, prior to sieving, with an acid to produce an aqueous solution; adding an alkaline aqueous solution to the aqueous solution to make the pH 10 or higher; and precipitating an iron compound containing manganese and zinc.

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