Method for manufacturing manganese zinc ferrite

Abstract

It is possible to recycle waste dry batteries simply and inexpensively without the need for high-temperature melting. 【Solution means】The method for manufacturing manganese zinc ferrite involves crushing waste dry batteries including at least one of alkaline manganese dry batteries and manganese dry batteries, sieving the crushed material of the waste dry batteries to obtain fine particles with a maximum particle diameter of 1 mm or less, generating 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.

Description

Technical Field

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

Background Art

[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 hard to say that the effective utilization and recycling of used dry batteries are being fully carried out. In addition, when recycling dry batteries, it is necessary to melt them at a high temperature, which not only discharges a large amount of carbon dioxide but also consumes a large amount of electric power. 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.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Non - Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] One embodiment aims to provide a method for manufacturing manganese - zinc ferrite that can recycle waste dry batteries simply and inexpensively without requiring high - temperature melting.

Means for Solving the Problems

[0006] The method for manufacturing manganese - zinc ferrite according to the embodiment includes crushing waste dry batteries including at least one of alkaline manganese dry batteries and manganese dry batteries, sieving the crushed matter of the waste dry batteries to obtain fine particles with a maximum diameter of individual particles of 1 mm or less, generating an aqueous solution by dissolving the fine particles in an acid, adding sodium hydroxide to the aqueous solution to make the pH 10 or more, and precipitating an iron compound containing manganese and zinc.

Effects of the Invention

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

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] The present inventors have found a method for generating and recycling high-quality manganese zinc ferrite from waste dry batteries by collecting alkaline manganese dry batteries, manganese dry batteries, etc., without performing high-temperature melting or the like. The method will be described in detail below. The method for producing manganese zinc ferrite described below can be utilized as a method for recycling waste dry batteries.

[0010] (Collected waste dry batteries) In order to produce manganese zinc ferrite, manganese dry batteries and alkaline manganese dry batteries containing raw materials such as manganese, zinc, and iron are targeted for collection. All of these dry batteries contain manganese in the positive electrode and zinc in the negative electrode. In addition, the outer can of the alkaline manganese dry battery is mainly made of steel. The outer can of the manganese dry battery may be made of zinc in some cases, but in some manganese dry batteries, steel is used for the outer can, similar to the alkaline manganese dry battery.

[0011] The inventors of the present invention propose to utilize the existing logistics network for the collection of these dry batteries. As an example, a method can be considered in which a common logistics system that delivers packages to ordinary households, company offices, factories, etc. by courier is applied, and waste dry batteries are collected from these delivery destinations on the return journey. At that time, for example, by motivating such as awarding points, the provider of waste dry batteries can be accustomed to disposing of waste dry batteries when receiving packages by courier, and it is considered that a constant collection system can be constructed.

[0012] (Crushing of waste dry batteries) Next, the collected waste dry batteries are crushed using a crusher. As the crusher, for example, a twin-screw crusher or the like can be used. An example of a twin-screw crusher is shown in FIG. 1.

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

[0014] The crusher 10 of the embodiment is configured as a twin-screw crusher including two screw rotors 15 as an example.

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

[0016] The hopper 11 is an inlet for the waste dry battery C to be crushed, and is provided at the upper part of the crusher 10. The crushing chamber 12 is provided below the hopper 11 and includes, for example, two screw rotors 15. These screw rotors 15 have shafts provided with screw blades, and as the screw rotors 15 rotate around these shafts, the waste dry battery C introduced from the hopper 11 into the crushing chamber 12 is crushed. The collection container 14 is provided below the crushing chamber 12 via the sieve 13, and the waste dry battery C that has become fine particles Pf passes through the sieve 13 and is accommodated.

[0017] The mesh of the sieve 13, that is, the holes (not shown) provided in the sieve preferably have a diameter of 1 mm or less. As a result, the mixed particles Pc in which particles having a particle size larger than 1 mm immediately after crushing by the screw rotor 15 are mixed are sorted by the sieve 13, and fine particles Pf composed of particles having a particle size of 1 mm or less are obtained. Further, by repeatedly crushing and refining the mixed particles Pc remaining in the crushing chamber 12 without passing through the sieve 13, finer particles Pf can be obtained.

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

[0019] In this way, by using the fine particles Pf obtained by crushing the waste dry battery C into fine particles as a raw material, the dissolution of the raw material described in detail later becomes easy, and high-quality manganese zinc ferrite can be obtained.

[0020] Here, the iron mainly contained in the outer package portion of the waste dry battery C is difficult to be crushed. Further, the crushed mixed particles Pc are likely to adhere to the side walls in the crushing chamber 12 and the like due to the influence of the electrolyte in the waste dry battery C and the humidity in the environment where the crusher 10 is placed. As the electrolyte, when the waste dry battery C is an alkaline manganese dry battery, for example, hydroxides of alkali metals such as potassium hydroxide are used, and when it is a manganese dry battery, for example, zinc chloride is used. These electrolytes act as binders, and there are cases where the mixed particles Pc, the fine particles Pf, and other crushed materials gather around the relatively large crushed material, iron, making it difficult to pass through the sieve 13.

[0021] Therefore, when the remaining amount of the waste dry battery C is zero, that is, when the waste dry battery C is in a fully discharged state, etc., it is preferable to crush the waste dry battery C in a low-humidity environment. It is also effective to send air into the crushing chamber 12 using a supply mechanism (not shown) and perform crushing in a state where the inside of the crushing chamber 12 is dried. However, even in this case, due to the reasons such as the difficulty of crushing described above, the iron component ratio in the fine particles Pf tends to be less than that in the mixed particles Pc.

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

[0023] Note that the crushing of the waste dry battery C is not limited to the twin-screw crusher shown above, and various crushers can be used as long as they can crush the waste dry battery C into fine particles Pf with a particle size of 1 mm or less. Examples of such crushers include an impact crusher that crushes an object by colliding it with a collision plate.

[0024] (Component analysis of fine particles) From the fine particles Pf obtained as described above, as will be described in detail later, manganese zinc ferrite is manufactured through various processes by a wet method. In the fine particles Pf obtained from randomly collected waste dry batteries, the component ratios of manganese, zinc, iron, etc. are different from time to time.

[0025] Therefore, in manufacturing manganese zinc ferrite, first, the component analysis of the obtained fine particles Pf is performed by, for example, fluorescence X-ray (XRF: X-Ray Fluorescence) analysis.

[0026] (Leaching of fine particles) Next, based on the above analysis results, the required amount of hydrochloric acid is calculated, and the required amount of 2 mol / liter hydrochloric acid is added to the above-mentioned fine particles Pf and stirred at a temperature of 50 °C for 60 minutes, for example. Since hydrochloric acid is a monovalent acid, the number of moles required for the above reaction is 2 to 4 moles per 1 mole of manganese, zinc, or iron.

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

[0028] Thereafter, the aqueous chloride solution is filtered to remove residues.

[0029] (Adjustment of component ratio) As described above, the component ratios of manganese, zinc, and iron in the fine particles Pf obtained from the crushed waste dry batteries sometimes vary. Among these, since iron in the waste dry batteries is difficult to be crushed and relatively large iron crushed materials aggregate with other crushed materials, in the fine particles Pf after passing through the sieve 13, compared with the mixed particles Pc that did not pass through the sieve 13, the component ratio of iron tends to be low.

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

[0031] Therefore, iron(III) chloride (FeCl3) is added to the aqueous solution of the chloride obtained as described above so as to have a preferable component ratio as manganese zinc ferrite. At this time, the addition amount of iron(III) chloride is adjusted so that the molar ratio of Fe2O3 to the total number of moles of MnO and ZnO becomes 1:1. The weight of iron(III) chloride required to make the molar ratio (MnO + ZnO):Fe2O3 = 1:1 is, for example, about 1.12 times the weight of the fine particles Pf obtained by crushing, more preferably 2 times or more. By adding about 1.12 times of iron(III) chloride, manganese-rich manganese zinc ferrite can be obtained, and by adding 2 times or more of iron(III) chloride, more crystalline manganese zinc ferrite can be obtained.

[0032] (Production of manganese zinc ferrite) Next, heat the above-mentioned aqueous solution of chloride to which iron(III) chloride has been added to 50 °C or higher, add an alkaline aqueous solution until the aqueous solution of chloride reaches pH 10 or higher, and stir 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 are required until a precipitate forms in the aqueous solution.

[0033] In this way, by making the aqueous solution of chloride alkaline, manganese, zinc, and iron that were ionized and dissolved in the aqueous solution precipitate as a precipitate of an iron compound of manganese and zinc. Thus, the precipitated precipitate is filtered, washed, and dried to obtain powdery manganese zinc ferrite.

[0034] As described above, the manganese zinc ferrite of the embodiment is produced.

[0035] In addition, in the above-mentioned leaching treatment of the fine particles Pf, it is also possible to use 2 mol / liter of sulfuric acid instead of 2 mol / liter of 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 1 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 (Fe2(SO4)3) can be added instead of iron(III) chloride. Furthermore, it is also possible to use nitric acid instead of hydrochloric acid in the leaching treatment and use a nitrate compound for the component adjustment.

[0036] (Summary) As global environmental problems become more serious, various initiatives are being carried out by companies and organizations. However, there is still no magic bullet for reducing carbon dioxide emissions. Under such circumstances, effective utilization and recycling of rapidly increasing industrial waste are also demanded. However, the collection rate of alkaline manganese dry batteries and manganese dry batteries, which are consumed in large quantities, remains at about a few percent. Furthermore, used or discarded dry batteries are melted at high temperatures, and then the contained metals such as manganese, zinc, and iron are separated by magnetic separation or the like for each type.

[0037] Thus, in the dry smelting recycling method involving high-temperature melting, a large amount of carbon dioxide is emitted and a great deal of electricity is consumed in itself. Also, a great deal of labor is required for magnetic separation of the melt. From this, it would be very beneficial if used dry batteries could be reused by a simple and inexpensive method that does not include a high-temperature treatment process 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 magnetic heads and transformers. Manganese zinc ferrite can be used as a filler for building materials such as bricks, tiles, and concrete blocks for general purposes, and by utilizing its excellent magnetic properties, it can also be used for disaster prevention applications such as temperature-sensitive switches and radio wave absorbers. Also, recent research has reported papers stating that ferrite-containing materials are effective as radiation shielding materials.

[0039] To produce manganese zinc ferrite compacts, commercially available powder raw materials are purchased, weighed, and mixed. If it is 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 manufacturing manganese-zinc ferrite of the embodiment, the mixed particles Pc, which are the crushed materials of waste dry batteries, are sieved through a sieve 13 to obtain fine particles Pf with a maximum diameter of 1 mm or less for each particle. 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 higher, and an iron compound containing manganese and zinc is precipitated.

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

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

[0043] According to the method for manufacturing manganese-zinc ferrite of the embodiment, an iron(III) salt is added to the above aqueous solution in which the fine particles Pf are dissolved, and the component adjustment is performed so that the ratio of the total number of moles of manganese(II) and zinc(II) to the number of moles of iron(III) in the above aqueous solution becomes 1:1. Thereby, a powder of manganese-zinc ferrite having preferable magnetic properties can be obtained.

[0044] (Modification example) In the above-described embodiment, waste dry batteries are crushed, and manganese-zinc ferrite is manufactured using the fine particles Pf obtained by passing through the sieve 13 as raw materials. Thereby, a powder of manganese-zinc ferrite having a high-quality crystal structure can be obtained.

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

[0046] As described above, iron in the waste dry battery is difficult to be crushed and aggregates with other crushed materials. Therefore, the mixed particles Pc contain more iron compared to the fine particles Pf that have passed through the sieve 13. Accordingly, 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 used as a raw material.

[0047] According to the method for producing manganese zinc ferrite of the modified example, an aqueous solution in which mixed particles Pc containing particles with a maximum diameter exceeding 1 mm before passing through the sieve 13 are dissolved in an acid is generated, an alkaline aqueous solution is added to the aqueous solution to make the pH 10 or higher, and an iron compound containing manganese and zinc is precipitated. Thereby, 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.

Example

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

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

[0050]

Table 1

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

[0052] Next, these samples S1 and S2 were subjected to a leaching treatment using hydrochloric acid. From the above analysis results, 22.6 mL of 2 mol / L hydrochloric acid was added to the sample S1 per gram of the sample S1, and 36.4 mL of 2 mol / L hydrochloric acid was added to the sample S2 per gram of the sample S2. Then, the temperature was raised to 50 °C and stirred for 60 minutes at a rotation speed of 450 times per minute.

[0053] Next, iron(III) chloride for component adjustment was added to the hydrochloric acid of the samples S1 and S2. From the above analysis results, 0.55 g of iron(III) chloride was added to the hydrochloric acid of the sample S1 per gram of the sample S1, and 1.17 g of iron(III) chloride was added to the hydrochloric acid of the sample S2 per gram of the sample S2.

[0054] Next, the aqueous solutions of the chlorides of the samples S1 and S2 with adjusted components were heated to 50 °C, and sodium hydroxide was added until the pH of each aqueous solution reached 10 or more. Then, stirring was carried out for 30 minutes while maintaining the temperature at 50 °C until a precipitate was formed, and the precipitate was precipitated.

[0055] The precipitated precipitate was filtered, washed, dried, and then the crystal phase was identified using X-ray diffraction (XRD) analysis to obtain the results shown in FIGS. 2 and 3.

[0056] FIG. 2 is a graph showing the phase identification results by XRD analysis of the precipitate using the sample S1 according to the example as a raw material. FIG. 3 is a graph showing the phase identification results by XRD analysis of the precipitate using the sample S2 according to the example as a raw material. In the graphs of FIGS. 2 and 3, the horizontal axis is the diffraction angle and the vertical axis is the integrated intensity.

[0057] As shown in FIGS. 2 and 3, it can be seen that manganese zinc ferrite composed of a single spinel phase suitable as a magnetic material is generated regardless of whether any of the samples S1 and S2 are used as raw materials. Also, sharper peaks are detected in FIG. 3 based on sample S2 than in FIG. 2 based on sample S1, indicating that higher-quality crystals are obtained.

Explanation of Reference Signs

[0058] 10 Crusher 11 Hopper 12 Crushing Chamber 13 Sieve 14 Recovery Container C Waste Dry Battery Pc Mixed Particles Pf Fine Particles

Claims

1. Crushing waste dry batteries including at least one of alkaline manganese dry batteries and manganese dry batteries; The crushed waste dry batteries are sieved to obtain fine particles each having a maximum particle size of 1 mm or less; The fine particles are dissolved in an acid to produce an aqueous solution; an alkaline aqueous solution is added to the aqueous solution to adjust the pH to 10 or more, thereby precipitating an iron compound containing manganese and zinc; Method for producing manganese zinc ferrite.

2. 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 components are 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 becomes 1:1; The method for producing manganese zinc ferrite according to claim 1.

3. The acid for dissolving the fine particles is 2 mol / liter hydrochloric acid; The iron (III) salt used to adjust the composition of the aqueous solution is iron (III) chloride. The method for producing manganese zinc ferrite according to claim 2.

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

5. The acid that dissolves the fine particles is 2 moles / liter of nitric acid; The iron (III) salt used to adjust the composition of the aqueous solution is iron (III) nitrate. The method for producing manganese zinc ferrite according to claim 2.

6. a water solution is generated by dissolving the crushed waste dry batteries, which include particles having a maximum particle diameter of more than 1 mm, in an acid before being sieved; an alkaline aqueous solution is added to the aqueous solution to adjust the pH to 10 or more, thereby precipitating an iron compound containing manganese and zinc; The method for producing manganese zinc ferrite according to claim 1.

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