Method and apparatus for recovering manganese contained in waste dry batteries

Abstract

The present invention recovers a high-purity manganese-containing solution from waste dry batteries at a high yield. The present invention is a manganese recovery method from waste dry batteries, which sequentially performs a sorting process of waste dry batteries; a crushing and sieving process of powder particles obtained from the waste dry batteries; an acid and oxidizing agent treatment process of the powder particles; a first solid-liquid separation process of separating a first leaching residue; an acid and reducing agent treatment process of a second leaching solution obtained from the first leaching residue; a second solid-liquid separation process of separating the second leaching solution; and a manganese extraction process of obtaining a manganese ion-containing solution from the second leaching solution, the manganese extraction process including a prescribed zinc removal process and an iron removal process in different orders.

Description

Technical Field

[0001] This invention relates to a method and apparatus for recovering valuable metals from waste dry cell batteries. Specifically, this invention relates to a method and apparatus for recovering manganese (Mn), a valuable metal, by treating discarded manganese dry cell batteries and / or alkaline manganese dry cell batteries with acid and oxidants, separating manganese (Mn) as a major valuable component suitable for use in waste dry cell batteries, and recovering manganese as high-purity manganese suitable for use in various batteries. Background Technology

[0002] In recent years, due to the depletion of metal resources and rising trading prices, there is a need to actively recover valuable metals from low-grade ore, concentrates, steel mill by-products, and industrial waste. For example, manganese, as a valuable metal, is essential in many industries, and it is believed that its future demand may exceed its reserves. Especially in iron and steel plants, where large amounts of manganese have historically been consumed as raw materials for steelmaking, securing manganese resources is extremely important. Furthermore, in recent years, the consumption of manganese in secondary batteries, such as lithium-ion batteries, has increased significantly, making securing manganese resources in this field an extremely serious issue.

[0003] On the other hand, within Japan, a massive amount of dry cell batteries are produced and consumed, and then disposed of as industrial waste. Some of these discarded dry cell batteries (waste dry cell batteries) have high manganese content. For example, manganese dry cell batteries and alkaline manganese dry cell batteries, which are representative of primary batteries, use manganese dioxide (MnO2) as the positive electrode material.

[0004] Therefore, if manganese can be recovered in high purity from these waste dry batteries, it would be promising from the perspective of ensuring a stable source of manganese.

[0005] However, in addition to manganese, waste dry cell batteries also contain metallic components such as zinc (Zn) and iron (Fe). The former is mainly found in the negative electrode material and electrolyte, while the latter is primarily contained in the outer casing of the dry cell battery. Therefore, when recovering manganese from waste dry cell batteries, it is important to separate metallic components such as zinc and iron from the manganese as much as possible.

[0006] The inventors have proposed a technology for separating zinc and iron from waste dry-cell batteries and recovering manganese with high purity. Patent document 1 discloses a "method and recovery equipment for recovering manganese from waste dry-cell batteries." For example... Figure 1 As shown, the proposal in Patent Document 1 is as follows: acid leaching is performed on the powder obtained by crushing and sieving waste dry batteries, mixing acid solution and reducing agent, and then zinc and iron are precipitated and removed, thereby obtaining high-purity manganese.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent document 1: International Publication No. 2021 / 075135. Summary of the Invention

[0010] However, the method disclosed in Patent Document 1 leaves room for further research on the yield of manganese. Specifically, in the powder obtained by crushing and sieving waste dry-cell batteries, the zinc content is second only to manganese. During acid leaching, a large amount of zinc is transferred to the leachate along with the manganese. Then, if a sulfiding agent is used to remove the zinc from the leachate by precipitation, some manganese is entrained and precipitates as a sulfide (co-precipitation), thus reducing the yield of manganese. Furthermore, sulfiding agents are more expensive than common acids and alkalis, so removing a large amount of zinc by precipitation using sulfiding agents also presents a cost problem.

[0011] The present invention was made in view of the above-mentioned problems, and its purpose is to provide a manganese recovery method and equipment for recovering manganese from waste dry batteries, which can recover the manganese contained in waste dry batteries as a high-purity manganese-containing solution with very little zinc and iron mixed in, and achieve a good yield.

[0012] It should be noted that "high-purity manganese-containing solution" here refers to a manganese-containing solution in which the levels of zinc and iron, which are impurities, are both below the analytical limit when analyzed using commonly used analytical methods specified in JIS standards, for example, less than 0.1 mg / L. Detailed Implementation

[0013] Manganese and / or alkaline manganese dry cell batteries are separated from waste dry cell batteries. During crushing and sieving, the materials constituting the dry cell batteries are separated into solids that remain on the sieve and powders that pass through. The main materials constituting the dry cell batteries are sheet-like packaging materials, zinc cans, brass rods, paper materials, and plastics, which, after crushing, become foil-like or sheet-like solids and are separated on the sieve. On the other hand, manganese dioxide (MnO2), carbon (C), zinc chloride (ZnCl2), ammonium chloride (NH4Cl), potassium hydroxide (KOH), or further generated through discharge such as manganese hydroxyl oxide (MnO(OH)), zinc hydroxide (Zn(OH)2), manganese hydroxide (Mn(OH)2), and zinc oxide (ZnO), become powders and are separated below the sieve. It should be noted that trace amounts of iron are unavoidably mixed into these powders.

[0014] In order to improve the yield of manganese, the inventors have repeatedly and thoroughly studied methods for selectively removing only zinc in advance while inhibiting the dissolution of manganese and promoting the leaching of zinc. As a result, by further adding an oxidant when the acid solution reacts with the powder particles, it is possible to inhibit the dissolution of manganese and preferentially leach and remove zinc into the leaching solution (acid-oxidant treatment step).

[0015] Furthermore, the inventors have obtained the following insight: by reacting the powder particles (first leaching residue) whose zinc content has been significantly reduced through the acid-oxidizing agent treatment process with acid and reducing agent to obtain a leachate (second leaching solution) that further leaches manganese, iron, and residual zinc, if the residual zinc and iron components are selectively precipitated and separated from the second leaching solution according to a prescribed procedure, a high-purity manganese solution can be obtained easily and with a high yield, regardless of the order of the precipitation and separation process.

[0016] As a more specific example of step A, the inventors confirmed the following: by performing a sulfide precipitation treatment process in which zinc ions remaining in the second leachate are selectively precipitated as sulfides (zinc-containing sulfides) by reacting sulfides such as sodium hydrosulfide (NaHS) with the second leachate, and a zinc separation process in which the obtained zinc-containing precipitate is separated, zinc components can be further removed from the second leachate (zinc removal process in step A), and the zinc ion concentration in the solution (third solution) left after the zinc removal process can be easily reduced to less than 0.1 mg / L, which is the analytical limit. Then, if the third solution is further subjected to an oxidation treatment process to further separate iron ions as iron-containing precipitates (iron separation process), a high-purity manganese solution (iron removal process in step A) can be easily and with a high yield as the solution (fourth solution) left after the separation of iron components.

[0017] In addition, as a specific alternative to step B, the inventors have also confirmed the following: by oxidizing the second leachate, for example, in air, the iron ions contained in the second leachate can be selectively precipitated, for example, as hydroxides, so that only iron components are preferentially separated from the second leachate, and the iron ion concentration in the solution (third solution) left after the separation of iron components is significantly reduced (iron removal process in step B); then, if a sulfide precipitation treatment is performed by reacting a sulfide such as sodium hydrosulfide with the third solution, the remaining zinc ions are further separated as zinc-containing precipitates, and a high-purity manganese solution is easily and with a high yield as the fourth solution left after separation (zinc removal process in step B).

[0018] The results of experiments (A) and (B) conducted by the inventors in accordance with steps A and B described above will be explained.

[0019] Experiment (A)

[0020] Manganese dry cell batteries and alkaline manganese dry cell batteries are separated from waste dry cell batteries (sorting process), and then further crushing and screening processes are carried out to obtain powder particles.

[0021] The obtained powder particles are mixed with an acid solution and an oxidizing agent under the following conditions to carry out an acid-oxidizing agent treatment process.

[0022] Acid solution: Sulfuric acid (H2SO4) (volume: 100mL, concentration: 1.0mol / L (approximately 8.7% by mass))

[0023] Oxidizing agent: Sodium hypochlorite (N a ClO) aqueous solution

[0024] (Above 5.0% available chlorine (Cl2), amount: 50% by mass relative to the acid solution)

[0025] Processing time: 1 hour of stirring

[0026] Solid-liquid ratio of powder / acid solution: 100 g / L

[0027] Next, the resulting mixture was filtered through filter paper with a pore size of 1 μm, and the first leachate and the first leaching residue were subjected to solid-liquid separation (first solid-liquid separation step). The concentrations of manganese and zinc in the separated first leaching residue were quantified by ICP emission spectroscopy. The compositional analysis results before and after the acid-oxidant treatment step are shown in Table 1. After the acid-oxidant treatment step, the zinc concentration in the separated first leaching residue decreased significantly to 3.53% by mass. On the other hand, since the addition of the oxidant effectively suppressed the dissolution of manganese into the first leachate, the manganese concentration in the first leaching residue increased significantly to 58.59% by mass. As a result, the yield of manganese from the powder to the first leaching residue was 99.99%.

[0028] [Table 1]

[0029]

[0030] As shown in Table 1, most of the zinc in the first leaching residue after the acid-oxidant treatment step is removed while maintaining the manganese content in the powder particles, but some zinc remains. Therefore, as described later, by performing acid-reducing treatment on the first leaching residue separated after the acid-oxidant treatment step, whereby an acid solution and a reducing agent are applied, to further leach the remaining zinc, and then performing sulfide precipitation treatment on the second leaching solution, the remaining zinc can be selectively and sufficiently precipitated, as detailed later. The result is an improved manganese yield and reliable, easy, and economical removal of zinc.

[0031] An acid-reducing agent treatment step is performed, in which an acid solution and a reducing agent are applied to the first leaching residue separated after the acid-oxidizing agent treatment step. Then, a second solid-liquid separation step is performed, in which the resulting mixture is filtered using filter paper with a pore size of 1 μm, yielding a second leachate and a second leaching residue. It should be noted that the acid solution used in the acid-reducing agent treatment step is sulfuric acid (concentration: 1.0 mol / L (approximately 8.7% by mass)), the reducing agent is 30% hydrogen peroxide (H₂O₂) in water, and the treatment time is 1 hour with stirring. Through this acid-reducing agent treatment step and the second solid-liquid separation step, a second leachate containing at least manganese ions, iron ions, and residual zinc ions is obtained.

[0032] The concentrations of manganese, zinc, and iron in the second leachate were quantitatively analyzed by ICP emission spectroscopy. The results showed that the manganese concentration was 31826 mg / L, the zinc concentration was 1919 mg / L, and the iron concentration was 163 mg / L.

[0033] Next, the obtained second leachate is subjected to a sulfide precipitation treatment process by adding sodium hydrosulfide as a sulfide under various conditions. It should be noted that the sodium hydrosulfide is added in a solution dissolved in distilled water.

[0034] The conditions for sulfide precipitation treatment are as follows.

[0035] Second leachate: 100mL

[0036] Types of sulfides: Sodium hydrosulfide

[0037] Sulfide addition amount: 1 to 3 equivalents of dissolved zinc in terms of sulfur (S).

[0038] The pH of the second leachate in the reaction is 0.5–5.

[0039] pH adjuster: 3M sulfuric acid or 100g / L sodium hydroxide (NaOH)

[0040] Processing time: 0.5 hours after adding sodium hydrosulfide and stirring.

[0041] In addition, after sulfide precipitation, solid-liquid separation (zinc separation step) was performed by filtration using 1 μm pore size filter paper. The components (zinc, iron, manganese) of the separated third solution were quantitatively analyzed using ICP emission spectroscopy. Since the pre-treatment with acid and oxidant removed most of the zinc, filter paper clogging was not observed in the zinc separation step, allowing for simple solid-liquid separation. It should be noted that the obtained analytical values ​​were corrected for the effects of dilution by adding sodium hydrosulfide solution and pH adjuster. The results are shown below. Figure 5 .

[0042] Depend on Figure 5(a) It is known that when the amount of sulfide added is 1 equivalent (sodium hydrosulfide: 1 equivalent), although the zinc precipitate is removed, it exceeds the analytical limit (0.1 mg / L) and is incomplete, and the final zinc removal rate is unstable when the pH of the second leachate is increased.

[0043] On the other hand, such as Figure 5 As shown in (b), when the amount of sulfide added is 2 equivalents (sodium hydrosulfide: 2 equivalents), the removal of zinc precipitation becomes significant. It is evident that, especially under conditions where the pH of the second leachate is above 3, the zinc concentration in the third solution after the zinc removal process (sulfide precipitation treatment process and zinc separation process) is less than the analytical limit (0.1 mg / L). Furthermore, even... Figure 5 (c) shows the same trend as the case with 2 equivalents when the amount of sulfide added is 3 equivalents (sodium hydrosulfide: 3 equivalents). In particular, when the zinc concentration in the second leachate is below the analytical limit (0.1 mg / L) at a pH above 3, the removal of zinc precipitation becomes significant.

[0044] It should be noted that, by Figure 5 It can be seen that iron precipitation is also removed during the zinc removal process. For example... Figure 5 As shown in (b), when the amount of sulfide added is 2 equivalents (sodium hydrosulfide: 2 equivalents), iron is precipitated and removed when the pH of the second leachate is above 3, and the iron concentration is reduced to about 1 mg / L when the pH is around 5. Figure 5 Under the conditions shown in (b), although some manganese precipitates due to the increase in pH, the first leaching residue, which maintains a high manganese content through an acid-oxidizing agent treatment process, is utilized in this application. Therefore, the manganese concentration in the third solution, which was previously reduced to around 19,000 mg / L, can be suppressed to around 25,000 mg / L.

[0045] Furthermore, it is known that Figure 5 (c) When the amount of sulfide added is 3 equivalents (sodium hydrosulfide: 3 equivalents), the iron precipitate is removed with the same trend as in the case of 2 equivalents. Figure 5 As shown in (c), the removal of iron precipitation is particularly significant when the pH of the second leachate is 5, with the amount removed to about 0.5 mg / L. Figure 5 (c) At pH 5, although some manganese precipitates due to the increase in pH, the first leaching residue in this application maintains a high manganese content through an acid-oxidant treatment process. Therefore, the manganese concentration in the third solution, which was previously reduced to about 15,000 mg / L, can be reduced to about 23,000 mg / L.

[0046] Regarding experiment (A), as described above, if the first leaching residue obtained by acid-oxidizing the powder is used, a large amount of zinc can be removed while maintaining manganese, which is beneficial for improving the final yield of recovered manganese. Furthermore, by using a zinc removal process for the second leaching solution containing manganese ions, iron ions, and residual zinc ions obtained from the acid-reducing process, the amount of zinc precipitate can be reduced. Therefore, co-precipitation of manganese during zinc precipitation can be suppressed, and problems such as filter paper clogging during zinc separation can be avoided, allowing zinc to be successfully precipitated, separated, and removed to below the analytical limit. Additionally, sometimes iron precipitates along with zinc. When the iron concentration is removed to a certain extent, it is considered to terminate the process at this stage. However, to remove iron more thoroughly, an iron removal process (oxidation treatment process and iron separation process) is further implemented, in which iron ions contained in the third solution separated after the zinc removal process precipitate as iron-containing precipitates such as hydroxides.

[0047] Experiment (B)

[0048] Following the same method as in Experiment (A), acid and reducing agent were applied to the first leaching residue obtained from the sorting, crushing and sieving, acid-oxidizing agent treatment, and first solid-liquid separation processes to obtain a second leachate and a second leaching residue. The concentrations of manganese, zinc, and iron in the separated second leachate were determined by ICP emission spectroscopy. The manganese concentration was 31826 mg / L, the zinc concentration was 1919 mg / L, and the iron concentration was 163 mg / L.

[0049] Next, the obtained second leachate is subjected to air aeration (oxidation treatment step) as an oxidation treatment. The air aeration conditions are as follows.

[0050] Blow-in rate: (same as the volume of the second leachate) / minute

[0051] Aeration time: 30 minutes

[0052] The pH of the second leachate in the reaction is 4–6.

[0053] pH adjuster: 3M sulfuric acid or 100g / L sodium hydroxide

[0054] Here, the blowing rate and aeration time are within the range of typical practical conditions (blowing rate: 0.1 to 1 times the solution volume per minute, aeration time: 15 to 60 minutes).

[0055] Then, the total volume of the second leachate after air aeration was filtered using 1 μm filter paper for solid-liquid separation (iron separation process). The concentrations of the components (zinc, iron, manganese) in the separated third solution were determined using ICP emission spectroscopy. It should be noted that the measured values ​​were corrected for dilution effects using a pH adjuster. The results are shown below. Figure 6 Since almost no manganese and zinc precipitation was observed during the oxidation process, therefore Figure 6 The figure only shows the iron concentration in the third solution after the iron removal process (oxidation treatment process and iron separation process).

[0056] Figure 6 It can be seen that in the second leachate with a pH of 4–6, iron is selectively precipitated and removed. It should be noted that, although not illustrated, manganese and zinc hardly precipitate within this pH range. At pH 6, although zinc is slightly precipitated, the amount is as small as approximately 10–20 mg / L. When the second leachate is at pH 5 or 6, iron precipitation is significantly reduced, with the iron concentration decreasing to less than 0.1 mg / L. Thus, simply applying air aeration, a cheap oxidation treatment, to the second leachate can substantially reduce the iron concentration.

[0057] Figure 6 In the process, the second leachate, adjusted to pH 5, is subjected to air aeration (oxidation treatment) to reduce the iron concentration to less than 0.1 mg / L. Iron separation is carried out through solid-liquid separation. The resulting third solution is further subjected to sulfide precipitation treatment under various conditions.

[0058] The conditions for sulfide precipitation treatment are as follows.

[0059] Third solution: 100mL

[0060] Types of sulfides: Sodium hydrosulfide

[0061] Sulfide addition amount: 1 to 3 equivalents of dissolved zinc (calculated as sulfur).

[0062] The pH of the third solution in the reaction is 0.5–5.

[0063] pH adjuster: 3M sulfuric acid or 100g / L sodium hydroxide

[0064] Processing time: 0.5 hours after adding sodium hydrosulfide and stirring.

[0065] Following the aforementioned sulfide precipitation process, solid-liquid separation (zinc separation process) is performed by vacuum filtration using 1 μm filter paper. The composition of the separated fourth solution is analyzed using ICP emission spectroscopy. Since the pre-treatment process using acid and oxidant removes most of the zinc, no clogging of the filter paper is observed during the zinc separation process, allowing for simple solid-liquid separation.

[0066] As a result, even with the addition of 1 equivalent of sulfide (sodium hydrosulfide: 1 equivalent), although zinc was removed by precipitation, the amount was greater than the analytical limit (0.1 mg / L) and incomplete. Furthermore, the final zinc removal rate was not stable when the pH of the third solution was increased.

[0067] On the other hand, when the amount of sulfide added is 2 equivalents (sodium hydrosulfide: 2 equivalents), the removal of zinc precipitation becomes significant, especially when the pH of the third solution is above 3, and the zinc concentration in the fourth solution after the zinc removal process is precipitated and removed before it is below the analytical limit (0.1 mg / L).

[0068] Furthermore, even when the amount of sulfide added was 3 equivalents (sodium hydrosulfide: 3 equivalents), the same trend as in the case of 2 equivalents was observed, with significant removal of zinc precipitation. It should be noted that even when the amount of sulfide added was 3 equivalents (sodium hydrosulfide: 3 equivalents) and the pH of the third solution was around 5, the manganese concentration in the fourth solution, which had previously been reduced to around 16,000 mg / L, was reduced to around 22,000 mg / L due to the high manganese content of the first leaching residue maintained through the acid-oxidant treatment process.

[0069] For experiment (B), as described above, if the first leaching residue obtained by the acid-oxidant treatment process on the powder particles is used, a large amount of zinc is removed while maintaining manganese, which is advantageous for improving the final yield of recovered manganese. Furthermore, if the second leaching solution containing manganese ions, iron ions, and residual zinc ions obtained by the acid-reducing agent treatment process is first subjected to oxidation treatment, a simple oxidation process called air aeration can be performed to prepare a solution in which most of the iron component is precipitated and removed (iron removal process). Then, if a sulfide precipitation treatment process is performed where the sulfide reacts with the subsequently separated third solution, the amount of zinc-containing precipitate is reduced, thus suppressing the co-precipitation of manganese during zinc precipitation and avoiding problems such as filter paper clogging during surface zinc separation, allowing zinc to be successfully precipitated and removed to below the analytical limit (zinc removal process).

[0070] Thus, according to experiments (A) and (B), it can be seen that by using the first leaching residue, which removes most of the zinc from the powder in the acid-oxidant treatment process as a pretreatment step, zinc and iron can be reliably and easily precipitated and separated at the same time, regardless of the order of the zinc removal and iron removal processes, and a high-purity manganese-containing solution can be produced with a high manganese yield.

[0071] This invention was completed based on the above insights and further research. The main point of this invention is as follows: A method for recovering manganese contained in waste dry-cell batteries, comprising the following steps in sequence:

[0072] (1) Sorting process: Separate one or both of manganese dry cell batteries and alkaline manganese dry cell batteries from the waste dry cell batteries.

[0073] The crushing and sieving process involves crushing and sieving one or both of the manganese dry batteries and alkaline manganese dry batteries separated in the above sorting process to obtain powder particles.

[0074] In the acid-oxidizing agent treatment step, an acid solution and an oxidizing agent are mixed with the powder particles obtained in the above-mentioned pulverizing and sieving steps to obtain a first leachate and a first leachate residue.

[0075] In the first solid-liquid separation step, the first leachate and the first leachate residue obtained in the above-mentioned acid-oxidant treatment step are separated.

[0076] In the acid-reducing agent treatment step, an acid solution and a reducing agent are mixed in the first leaching residue separated in the first solid-liquid separation step to obtain a second leaching solution and a second leaching residue.

[0077] The second solid-liquid separation process separates the second leachate and the second leachate residue obtained in the acid-reducing agent treatment process.

[0078] In the manganese extraction process, zinc ions, iron ions, and manganese ions contained in the second leachate separated in the second solid-liquid separation process are removed to obtain a solution containing the aforementioned manganese ions.

[0079] The manganese extraction process includes zinc removal and iron removal processes in different sequences.

[0080] The zinc removal process described above includes a sulfide precipitation treatment process in which the zinc ions react with sulfides to precipitate the zinc ions, and a zinc separation process in which the zinc-containing precipitate is further separated.

[0081] The aforementioned iron removal process includes an oxidation treatment process that oxidizes the iron ions to precipitate them, and an iron separation process that further separates the resulting iron-containing precipitate.

[0082] (2) According to the recovery method described in (1), wherein the oxidant in the above-mentioned acid-oxidant treatment step is any one of sodium hypochlorite solution, oxygen, ozone, and potassium permanganate solution.

[0083] (3) The recovery method according to (1) or (2) wherein the acid solution in the above acid-oxidant treatment step is dilute sulfuric acid with a mass percentage concentration of 1.4% to 45% or dilute hydrochloric acid with a mass percentage concentration of 1% to 14%.

[0084] (4) The recovery method according to any one of (1) to (3), wherein the solid-liquid ratio of the powder to the acid solution in the above-mentioned acid-oxidant treatment step is 50 g / L or more.

[0085] (5) The recovery method according to any one of (1) to (4), wherein the acid solution in the above-mentioned acid-reducing agent treatment step is dilute sulfuric acid with a mass percentage concentration of 1.4% to 45% or dilute hydrochloric acid with a mass percentage concentration of 1% to 14%.

[0086] (6) The recovery method according to any one of (1) to (5), wherein the reducing agent in the above-mentioned acid-reducing agent treatment step is any one of hydrogen peroxide, sodium sulfide, sodium bisulfite, sodium thiosulfate and ferric sulfate.

[0087] (7) The recovery method described in any one of (1) to (6), wherein the manganese extraction process is performed in the order of the zinc removal process followed by the iron removal process.

[0088] In the above-mentioned zinc removal process, after the sulfide precipitation treatment process in which the sulfide reacts with the second leaching solution to precipitate zinc ions in the second leaching solution, a zinc separation process is performed to separate the obtained zinc-containing precipitate with a third solution containing manganese and iron ions.

[0089] In the above-mentioned iron removal process, after performing an oxidation treatment process in which the third solution obtained in the above-mentioned zinc removal process is oxidized to precipitate iron ions in the third solution, an iron separation process is performed in which the iron-containing precipitate is separated from the fourth solution containing manganese ions.

[0090] (8) The recovery method according to (7), wherein, in the above-mentioned sulfide precipitation treatment step, the second leachate is adjusted to pH: 2 to 6.

[0091] (9) The recovery method according to (7) or (8), wherein, in the above-mentioned oxidation treatment step, the above-mentioned third solution containing manganese ions and iron ions is aerated with air, or an oxidant is further added to the third solution, and the third solution is adjusted to pH: 3 to 7.

[0092] (10) The recovery method according to any one of (1) to (6), wherein the manganese extraction step is performed in the order of the iron removal step followed by the zinc removal step.

[0093] In the above-mentioned iron removal process, after performing an oxidation treatment step to oxidize the second leachate and precipitate the iron ions in the second leachate, an iron separation step is performed to separate the obtained iron-containing precipitate from the iron in a third solution containing manganese and zinc ions.

[0094] In the zinc removal process described above, after performing a sulfide precipitation treatment process in which the sulfide reacts with the third solution obtained in the iron removal process to precipitate zinc ions in the third solution, a zinc separation process is performed to separate the obtained zinc-containing precipitate with a fourth solution containing manganese ions.

[0095] (11) According to the recovery method described in (10), wherein in the above-mentioned sulfide precipitation treatment step, the third solution containing manganese ions and zinc ions is adjusted to pH: 2 to 6.

[0096] (12) The recovery method according to (10) or (11), wherein, in the above-mentioned oxidation treatment step, the second leachate is aerated with air and the second leachate is further adjusted to pH: 3 to 7.

[0097] (13) The recovery method according to any one of (1) to (12), wherein the sulfide used in the above-mentioned sulfide precipitation treatment step is any one of sodium hydrosulfide, sodium sulfide, and hydrogen sulfide.

[0098] (14) A device for recovering manganese contained in waste dry batteries, comprising the following devices in sequence:

[0099] The sorting device separates one or both of manganese dry batteries and alkaline manganese dry batteries from waste dry batteries.

[0100] A pulverizing device is used to pulverize one or both of the manganese dry cell batteries and alkaline manganese dry cell batteries that have been separated by the sorting device, and to obtain pulverized material.

[0101] A screening device performs a screening process on the pulverized material obtained by the above-mentioned pulverizing device to obtain powder particles.

[0102] An acid-oxidizing agent treatment tank is used to treat the powder particles obtained from the screening device with an acid solution and an oxidizing agent.

[0103] The first solid-liquid separation device separates the first leachate and the first leachate residue obtained from the acid-oxidant treatment tank.

[0104] An acid-reducing agent treatment tank is used to treat the first leaching residue separated by the first solid-liquid separation device with an acid solution and a reducing agent.

[0105] The second solid-liquid separation device separates the second leachate and the second leachate residue obtained from the acid-reducing agent treatment tank.

[0106] The manganese extraction apparatus removes zinc ions and iron ions from the second leachate separated by the second solid-liquid separation apparatus, thereby obtaining a solution containing manganese ions.

[0107] The aforementioned manganese extraction unit group includes a zinc removal unit group and an iron removal unit group in different orders.

[0108] The zinc removal unit includes a sulfide precipitation treatment tank that reacts sulfides with the zinc ions to precipitate the zinc ions, and a zinc separation unit that further separates the obtained zinc-containing precipitate into solid and liquid components.

[0109] The iron removal unit includes an oxidation treatment tank for oxidizing the iron ions to precipitate them and an iron separation device for further solid-liquid separation of the resulting iron-containing precipitate.

[0110] Invention Effects

[0111] According to the present invention, manganese, a valuable component contained in waste dry batteries, is separated from zinc and iron components with high precision and ease. This allows for the high-purity recovery of manganese, which can be used as a raw material for secondary battery electrode materials, with a high yield and low cost, resulting in significant industrial benefits. Attached Figure Description

[0112] Figure 1 This describes the manganese recovery process disclosed in Patent Document 1.

[0113] Figure 2 This is a description of the steps in the manganese recovery method of the present invention.

[0114] Figure 3 This is a flowchart illustrating one embodiment (step A) of the manganese recovery method of the present invention.

[0115] Figure 4 This describes another embodiment (step B) of the manganese recovery method of the present invention.

[0116] Figure 5 It means according to Figure 3 The graph shows the effect of sulfide addition ((a) sodium hydrosulfide: 1 equivalent, (b) sodium hydrosulfide: 2 equivalent, (c) sodium hydrosulfide: 3 equivalent) and pH conditions on the precipitation removal of zinc, iron and manganese in the sulfide precipitation treatment process.

[0117] Figure 6 It means according to Figure 4 The figure shows the effect of pH on the removal of iron precipitation in the oxidation process.

[0118] Figure 7 This is a schematic diagram illustrating one embodiment (configuration A) of the manganese recovery device of the present invention.

[0119] Figure 8 A schematic diagram illustrating another embodiment (configuration B) of the manganese recovery device of the present invention.

[0120] Figure 9 This is a graph showing the effect of the amount of oxidant added in the acid-oxidant treatment process on the leaching removal of oxidants from manganese and zinc. Detailed Implementation

[0122] This invention relates to a method and equipment for recovering manganese from waste dry-cell batteries. The manganese component, a valuable component found in the waste dry-cell batteries, is separated from the zinc and iron components commonly found in the batteries. The manganese is then recovered as a high-purity manganese-containing solution with a high yield. Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings. These embodiments are preferred examples of the invention, and the invention is not limited to these examples.

[0123] (Manganese recovery methods)

[0124] like Figure 2 As shown, the manganese recovery method of the present invention sequentially includes a sorting step, a crushing and sieving step, an acid and oxidizing agent treatment step, a first solid-liquid separation step, an acid and reducing agent treatment step, a second solid-liquid separation step, and a manganese extraction step. Furthermore, the manganese extraction step includes, in different orders, a predetermined zinc removal step and an iron removal step.

[0125] The recycling method of the present invention, following the steps specified above, can reliably and easily remove components other than manganese from waste dry-cell batteries. As a result, according to the recycling method of the present invention, manganese can be easily recovered from waste dry-cell batteries with high purity and high yield, to the extent that it can be used as a raw material for secondary battery electrode materials. The recycling method of the present invention can be appropriately implemented using the manganese recycling equipment described later.

[0126] Sorting process

[0127] Waste dry cell batteries are typically recycled as a mixture of various types. Therefore, in this invention, one or both of manganese dry cell batteries and alkaline manganese dry cell batteries (manganese dry cell batteries and / or alkaline manganese dry cell batteries) are separated from the recycled waste dry cell batteries. In subsequent processes, to effectively extract manganese, only manganese dry cell batteries may be separated, only alkaline manganese dry cell batteries may be separated, or both may be separated. As a sorting method, any method can be used, such as manual sorting or mechanical sorting using a sorting device.

[0128] Crushing and sieving process

[0129] Next, the manganese dry cell batteries and / or alkaline manganese dry cell batteries separated in the sorting process are crushed. The purpose of crushing is to remove as much material as possible from the constituent materials of the manganese dry cell batteries and / or alkaline manganese dry cell batteries separated in the sorting process, except for those containing manganese, zinc, and carbon.

[0130] If these waste dry-cell batteries are shredded, the packaging materials (iron, plastic, and paper, etc.), the zinc can (the negative electrode material of manganese dry-cell batteries), and the brass rod (the current collector of alkaline manganese dry-cell batteries) become foil-like or sheet-like solids. On the other hand, manganese dioxide (the positive electrode material), carbon rod (the current collector of manganese dry-cell batteries), zinc powder (the negative electrode material of alkaline manganese dry-cell batteries), compounds such as manganese hydroxide, zinc hydroxide, and zinc oxide generated during discharge, and various electrolytes become finer powder particles than the foil-like or sheet-like solids.

[0131] The shredding of waste dry-cell batteries is typically done using a shredding device. There are no particular limitations on the type of shredding device; however, it is preferable to use one that effectively separates solids such as the packaging materials constituting the dry-cell batteries from the powder particles after shredding. For example, a dual-shaft rotary shredder can be considered as such a device.

[0132] The mesh size of the sieve used for sieving the above-mentioned pulverized material (sieving of foil-shaped or flake-shaped solids and powder particles) is preferably 1 mm or more, preferably 20 mm or less, more preferably 10 mm or less, and even more preferably 3 mm or less. The mesh size is preferably about 1 to 20 mm, more preferably about 1 to 10 mm, and even more preferably about 1 to 3 mm. If the mesh size is above or below the aforementioned lower limit, more powder particles containing manganese can be ensured. Furthermore, if the mesh size is below the aforementioned upper limit, solids containing components other than manganese can be further excluded, allowing for more efficient subsequent processes.

[0133] Therefore, if waste dry cell batteries are crushed and then sieved using the aforementioned mesh screen, large solids such as packaging materials can be removed from the waste dry cell batteries, and powder particles mainly containing manganese, zinc and carbon can be effectively obtained.

[0134] Thus, the powder obtained through the crushing and sieving process is the main component of manganese dry batteries and / or alkaline manganese dry batteries, namely manganese dioxide, carbon, zinc chloride or ammonium chloride, potassium hydroxide, and further mixed with manganese hydroxide, zinc hydroxide, manganese hydroxide, and zinc oxide generated through discharge. It should be noted that iron components are usually inevitably mixed into this powder.

[0135] Acid and oxidant treatment process

[0136] The acid-oxidant treatment step is a key feature of the recovery method described in this application. In this step, an acid solution and an oxidant are mixed into the powder obtained from the crushing and sieving process. In addition to the acid solution, the oxidant also functions, thereby increasing the valence of manganese in the powder and preventing manganese from leaching into the first leaching solution, while primarily leaching zinc from the powder into the first leaching solution. The result is a first leaching residue with a high manganese content and a significantly reduced zinc content, which is beneficial for improving the manganese yield.

[0137] The acid solution used in the acid-oxidant treatment process can be a general acid, or it can be sulfuric acid, nitric acid (HNO3), hydrochloric acid (HCl), or other acids. The appropriate acid can be selected based on price and purpose, but considering cost and ease of procurement, sulfuric acid or hydrochloric acid is preferred as the acid solution.

[0138] When using sulfuric acid, it is preferable to use dilute sulfuric acid with a concentration of 1.4% to 45% by mass. More specifically, the sulfuric acid concentration is preferably 1.4% or more, more preferably 2% or more, more preferably 5% or more, preferably 45% or less, more preferably 30% or less, and even more preferably 25% or less. Dilute sulfuric acid with a concentration of 2% to 30% is more preferred, and dilute sulfuric acid with a concentration of 5% to 25% is even more preferred.

[0139] When using hydrochloric acid, it is preferable to use dilute hydrochloric acid with a concentration of 1% to 14% by mass. More specifically, the concentration of hydrochloric acid is preferably 1% or more, more preferably 2% or more, more preferably 14% or less, and even more preferably 8% or less. A dilute hydrochloric acid with a concentration of 2% to 8% is more preferred.

[0140] If the concentration of the acid solution in the acid-oxidant treatment process is below the aforementioned lower limit, it will be difficult to fully leach the zinc component from the powder into the first leaching solution, easily resulting in the formation of a large amount of fine zinc-containing precipitates in the subsequent zinc removal process. As a result, manganese is easily co-precipitated in the zinc separation process, becoming a significant factor in reducing the manganese yield. In addition, the zinc-containing precipitates cause clogging of filter paper, filter cloth, etc., making it difficult to easily remove the zinc component. On the other hand, if the concentration of the acid solution in the acid-oxidant treatment process exceeds the aforementioned upper limit, the manganese intended for recovery will also be easily over-leached into the first leaching solution, ultimately making it difficult to obtain a high-concentration manganese-containing solution with a high yield.

[0141] Commercially available sulfuric acid or hydrochloric acid can be used, but diluting industrial-grade or waste acid with low levels of harmful metals can reduce the cost of the acid solution. Additionally, the "mass % concentration" here is calculated by dividing the mass of the acid in the solution by the total mass of the solution and then multiplying by 100.

[0142] It should be noted that, even when using any acid solution, the acid concentration required for zinc leaching varies depending on the solid-liquid ratio of the powder to the acid solution, the amount of powder, the zinc content in the powder, and the form of zinc in the powder. Therefore, it is preferable to determine the optimal acid concentration by conducting preliminary experiments assuming an actual process.

[0143] The oxidant used in the acid-oxidant treatment process is added to inhibit the dissolution of manganese. There is no particular type of oxidant; general oxidants can be used. However, oxidants containing heavy metals other than manganese, such as potassium dichromate (K₂Cr₂O₇), may leave the heavy metal components as impurities in the manganese. Therefore, it is preferable to use oxidants that do not contain heavy metals other than manganese, such as sodium hypochlorite solution, oxygen (O₂), ozone (O₃), or potassium permanganate (KMnO₄) solution. Sodium hypochlorite solution is more preferred from the viewpoint of price and oxidizing power. It should be noted that hydrogen peroxide acts as a reducing agent in this system and is therefore unsuitable.

[0144] When the oxidant is a gas such as oxygen or ozone, it can be added by blowing the oxidant into the acid solution. As an example, the blowing rate of the oxidant can be 0.25 to 3 times the volume of the acid solution at a flow rate per minute (e.g., 25 to 300 mL / min of oxidant relative to 100 mL of acid solution), and this should ultimately be determined through preliminary experiments.

[0145] In the acid-oxidant treatment process, the solid-liquid ratio (powder (g) / acid solution (L)) of the powder to the acid solution is preferably 50 g / L or more, more preferably 100 g / L or more, and more preferably 500 g / L or less. If the solid-liquid ratio is less than the lower limit mentioned above, the size of the reaction tank required to process the powder increases, and equipment costs increase. In addition, if the acid solution becomes excessive relative to the powder, manganese, as the target component, is easily leached into the first leaching solution. On the other hand, if the solid-liquid ratio exceeds the upper limit mentioned above, the viscosity of the mixture of powder and acid solution becomes high, making it difficult to stir sufficiently. Furthermore, if the acid solution becomes insufficient relative to the powder, it becomes difficult for the acid solution to fully leach zinc into the first leaching solution, thus making it difficult to effectively remove zinc from the powder.

[0146] The above-mentioned preferred solid-liquid ratio is applicable regardless of whether the mixed oxidant is a liquid such as sodium hypochlorite solution and potassium permanganate solution, or a gas such as oxygen or ozone.

[0147] Taking the case where the oxidant is a liquid such as sodium hypochlorite as an example, from the viewpoint of ensuring that the first leaching residue contains manganese in a high yield, the amount of oxidant added in the acid-oxidant treatment step is preferably 20% by mass or more, more preferably 50% by mass or more, relative to the acid solution. Furthermore, the effective chlorine concentration of the sodium hypochlorite used is preferably 5% or more. There are no particular limitations on the stirring temperature in the acid-oxidant treatment step, but it is generally 0–100°C, and the stirring time is preferably 30 minutes or more, preferably 120 minutes or less. If the stirring time is less than 30 minutes, the reaction may not be able to complete; on the other hand, if it exceeds 2 hours, the reaction is difficult to proceed further.

[0148] When the oxidant is a gas such as oxygen or ozone, the oxidant injection rate is preferably at least 0.25 times the volume of the acid solution per minute, and more preferably at least 3 times the volume per minute. The stirring temperature and stirring time are the same as those for the liquid oxidant described above.

[0149] First solid-liquid separation process

[0150] In the first solid-liquid separation process, the first leachate obtained from the acid-oxidant treatment process and the first leaching residue are subjected to solid-liquid separation. The separated first leachate typically contains mainly leached zinc ions, and sometimes also contains manganese and iron ions partially dissolved along with zinc. However, in this application, by adding an oxidant to suppress the dissolution of manganese, the manganese content in the first leachate is controlled to be lower than before. On the other hand, the separated solid first leaching residue mainly contains manganese, iron, and residual zinc. In this application, by adding an oxidant to suppress the dissolution of manganese, the manganese content in the first leaching residue is controlled to be higher than before, for example, exceeding 50% by mass, or even exceeding 55% by mass, as shown in Table 1.

[0151] There are no particular limitations on the solid-liquid separation method. Commonly used methods such as gravity sedimentation, filtration, centrifugation, filter press, and membrane separation are preferred in the solid-liquid separation process.

[0152] Acid-reducing agent treatment process

[0153] In the acid-reducing agent treatment process, an acid solution and a reducing agent are mixed in the first leaching residue obtained from the acid-oxidizing agent treatment process and the first solid-liquid separation process, so that the manganese component contained in the first leaching residue is almost completely leached into the second leaching solution obtained in the subsequent process. The first leaching residue after the acid-oxidizing agent treatment process contains manganese in a high yield, thus it is also easy to increase the manganese yield in the second leaching solution obtained using the first leaching residue.

[0154] Here, in this specification, "almost completely" means that when a sample of residue after a certain process (in this case, the second leaching residue) is analyzed according to the analytical method specified in the commonly used JIS standard, the amount of the target component (in this case, manganese) is less than the analytical limit, for example, less than 0.1 mg / L.

[0155] The acid solution in the acid-reducing agent treatment process is added in conjunction with a reducing agent primarily to further leach the zinc components remaining in the first leaching residue, while also leaching the manganese components. The acid used in the acid solution can be a general acid, or an acid of a type and condition that suitably follows the above-described acid-oxidizing agent treatment process.

[0156] If the concentration of the acid solution in the acid-reducing agent treatment process is not lower than the aforementioned lower limit, it will be difficult to fully leach the manganese component in the first leaching residue into the second leaching solution, and the manganese recovery rate (finished product yield) will easily decrease. On the other hand, if the concentration of the acid solution in the acid-reducing agent treatment process is greater than the aforementioned upper limit, the amount of alkaline reagent required to adjust the pH in subsequent processes may increase, leading to a deterioration in costs.

[0157] It should be noted that the zinc component remaining in the first leaching residue after the acid-oxidizing agent treatment process is almost completely dissolved (leached) if the acid concentration increases, regardless of the presence of a reducing agent.

[0158] Furthermore, from the viewpoint of maximizing the efficiency of acid-reducing agent treatment, it is preferable to set the solid-liquid ratio (first leaching residue (g) / acid solution (L)) of the first leaching residue to the acid solution in the acid-reducing agent treatment process to 50 g / L or more. On the other hand, if the solid-liquid ratio exceeds 800 g / L, the viscosity may increase, causing operational problems, or the yield during the solid-liquid separation process may deteriorate. Therefore, the solid-liquid ratio is preferably set to 800 g / L or less. Additionally, the treatment temperature (atmosphere temperature, acid solution temperature, etc.) for acid-reducing agent treatment is sufficient at room temperature (around 15–25°C), but heating is also possible. The heating temperature can be set, for example, to 60–80°C. If heating is performed, as the temperature is increased within the range where the treatment solution does not boil, the reaction efficiency can be expected to improve. The treatment time for acid-reducing agent treatment is preferably 5 minutes or more, and preferably 6 hours or less.

[0159] The reducing agent is mainly added to reduce the manganese components with valences such as trivalent and tetravalent, which are poorly soluble in acids, contained in the first leaching residue, thereby leaching them out effectively. Various commonly used reducing agents are suitable. Examples of suitable reducing agents include hydrogen peroxide, sodium sulfide (Na₂S·9H₂O), sodium bisulfite (NaHSO₃), sodium thiosulfate (Na₂S₂O₃), and ferric sulfate (FeSO₄·7H₂O). However, sulfur-based reducing agents can produce corrosive gases such as sulfur dioxide (SO₂) and hydrogen sulfide (H₂S), which requires attention from a safety perspective. From this viewpoint, hydrogen peroxide is a more preferred reducing agent.

[0160] It should be noted that the amount of reducing agent added (g) depends on the form of manganese contained in the first leaching residue, and therefore there is no particular limitation, but about 1 to 500 g / L relative to the acid solution (L) is sufficient.

[0161] Second solid-liquid separation process

[0162] In the second solid-liquid separation process, the second leachate and the second leaching residue obtained in the acid-reducing agent treatment process are subjected to solid-liquid separation. The separated second leachate contains manganese ions, iron ions, and residual zinc ions. On the other hand, the separated solid second leaching residue is mainly a result of carbon residue. Thus, it is possible to separate the manganese, zinc, and iron components contained in the powder and the first leaching residue from the carbon.

[0163] There are no particular limitations on the solid-liquid separation method. In the solid-liquid separation process, commonly used methods such as gravity sedimentation separation, filtration, centrifugation, filter press, and membrane separation are preferred.

[0164] Manganese extraction process

[0165] A manganese extraction process is required, which removes zinc and iron ions from the second leachate separated in the second solid-liquid separation process to obtain a high-purity manganese-containing solution (manganese-containing solution). Specifically, the manganese extraction process includes a prescribed zinc removal process and an iron removal process in different sequences. More specifically, the zinc removal process includes a sulfide precipitation treatment process in which zinc ions are precipitated by reacting sulfides with them, and a zinc separation process in which the resulting zinc-containing precipitate is separated. Similarly, the iron removal process includes an oxidation treatment process in which iron ions are oxidized to precipitate, and an iron separation process in which the resulting iron-containing precipitate is separated.

[0166] In this way, zinc ions and iron ions are selectively precipitated in the manganese extraction process, and zinc ions and iron ions are reliably removed from the second leachate, thereby enabling the easy recovery of manganese as the target component with high purity and high yield.

[0167] In the manganese extraction process, a zinc removal step (step A) can be performed first to preferentially remove zinc ions through precipitation, or an iron removal step (step B) can be performed first to preferentially remove iron ions through precipitation. From the perspective of simplifying the process, it is preferable to perform the iron removal step first.

[0168] In step A, a mixture of zinc-containing precipitate and a third solution containing manganese and iron ions is first obtained from the second leachate, and then they are separated. In step B, a mixture of iron-containing precipitate and a third solution containing manganese and zinc ions is first obtained from the second leachate, and then they are separated. Steps A and B will be described in detail below.

[0169] Zinc removal process (Step A)

[0170] In the zinc removal process of step (A), the second leachate, after solid-liquid separation, first undergoes a sulfide precipitation treatment. In this sulfide precipitation treatment, the sulfides react with the second leachate, causing the zinc ions, which are the main residual ions in the second leachate, to precipitate as zinc sulfides and be removed from the second leachate. Through this treatment, a mixture of a third solution containing manganese and iron ions and the zinc-containing precipitate is obtained from the second leachate.

[0171] The second leachate separated in the second solid-liquid separation process contains manganese ions, iron ions, and residual zinc ions. If sulfides react with the second leachate, the divalent metal ions and sulfide ions (S...) will... 2- The reaction produces a sulfide that precipitates. The ease of precipitation of this sulfide depends on its solubility product K. SP The solubility products of manganese, zinc, and iron sulfides are shown below.

[0172] MnS:K SP =2.5×10 -10

[0173] ZnS:K SP =1.6×10 -24

[0174] FeS:K SP =6.3×10 -18

[0175] (Lange, NA: Lange's Handbook of Chemistry.Thirteenth edition1985)

[0176] Solubility product K SP The lower the value, the easier it is for sulfides to form. Therefore, among manganese, zinc, and iron, zinc is the most likely to form sulfides. Thus, by reacting the second leachate containing manganese, zinc, and iron ions with sulfides, zinc can be selectively precipitated as a sulfide. Furthermore, by adjusting the concentration of sulfide ions and the pH of the second leachate, the concentration of zinc ions in the second leachate can be easily reduced to below the analytical limit (0.1 mg / L).

[0177] Here, as described above, if the second leachate contains a large amount of zinc ions, a large amount of fine zinc-containing precipitate is generated due to the sulfide precipitation process, thus promoting manganese co-precipitation and easily reducing the final manganese yield. Furthermore, the zinc separation process is difficult because it easily clogs filter cloths during subsequent solid-liquid separation. However, in this invention, most of the zinc component in the powder is removed in the acid-oxidant treatment process before the sulfide precipitation process, while the manganese component is retained. Therefore, manganese co-precipitation can be effectively avoided, thus improving the final manganese yield. In addition, the amount and quality of the zinc-containing precipitate can be controlled, allowing for a simple and efficient zinc separation process described later.

[0178] Suitable examples of sulfides that function include sodium hydrosulfide, sodium sulfide (NaS), and hydrogen sulfide. It should be noted that hydrogen sulfide is a gas and therefore requires aeration. Therefore, sodium hydrosulfide and sodium sulfide are more preferred as sulfides that function.

[0179] The amount of sulfide that plays a role is preferably 1.1 to 5 equivalents relative to the sulfur content of dissolved zinc. The amount of sulfide, relative to the sulfur content of dissolved zinc, is preferably 1.1 equivalents or more, more preferably 2 equivalents or more, preferably 5 equivalents or less, more preferably 3 equivalents or less, and even more preferably less than 3 equivalents. If the amount of sulfide is above the aforementioned lower limit, zinc ions can be precipitated more effectively. Furthermore, if the amount of sulfide is below the aforementioned lower limit, the precipitation of undesirable manganese ions can be more easily suppressed, and excessive amounts of sulfide that would be economically disadvantageous can be prevented.

[0180] Furthermore, when the pH of the second leaching solution used for sulfide treatment is below 2, zinc precipitation tends to be insufficient. On the other hand, when the pH exceeds 6, the amount of manganese precipitated increases, significantly reducing the amount of manganese that can be recovered, exacerbating manganese loss, and easily lowering the manganese yield. Based on this viewpoint, the pH of the second leaching solution in the sulfide precipitation treatment process is preferably 2 or higher, more preferably 3 or higher, preferably 6 or lower, more preferably 5 or lower, and even more preferably less than 5. The pH of the second leaching solution is preferably pH 2 to 6, more preferably pH 2 to 5, further preferably pH 3 to 5, and even more preferably pH 3 or higher and less than 5.

[0181] Next, in the zinc removal process in step (A), the mixture obtained in the above-mentioned sulfide precipitation treatment process is separated into a third solution and a zinc-containing precipitate to remove the zinc component.

[0182] More specifically, the third solution containing manganese and iron ions obtained in the sulfide precipitation process is separated from the zinc-containing precipitate, which mainly contains residual zinc sulfide precipitate. This allows for easy separation of the zinc component from the mixture after the sulfide precipitation process, yielding a third solution containing manganese and iron ions. The separation method is not particularly limited and can follow the solid-liquid separation process described above. If the generated zinc-containing precipitate is large or fine, problems such as manganese co-precipitation or filter cloth clogging during zinc separation may occur. However, in this invention, since most of the zinc component in the powder is removed beforehand in the acid-oxidant treatment process while retaining the manganese component, manganese co-precipitation can be effectively avoided, improving the final manganese yield. Furthermore, the amount and fineness of the zinc-containing precipitate can be suppressed, making the zinc separation process simple and effective.

[0183] It should be noted that in the above-described sulfide precipitation process, there is a possibility that a portion of the iron is precipitated and removed from the solution. In this case, it is assumed that the process is terminated at this stage if the iron concentration is reduced to below a predetermined level. However, in step (A), in order to further remove iron and obtain high-purity manganese, an iron removal process described later is also performed.

[0184] Iron removal process (Step A)

[0185] In step (A), after the zinc removal process described above, an iron removal process is performed. In the iron removal process of step (A), the third solution containing manganese and iron ions obtained from the previous zinc removal process can first undergo an oxidation treatment process, separating the iron ions in the third solution as an iron-containing precipitate to remove the iron component. Through this treatment, a mixture of a high-purity fourth solution (manganese-containing solution) containing manganese ions and the iron-containing precipitate is obtained from the third solution.

[0186] As an oxidation treatment method, including a preferred pH for the third solution, the oxidation treatment method in step (B) described later can be followed. Here, if the third solution obtained through the sulfide precipitation treatment step is aerated with air under practical conditions, there is a possibility that the iron component in the third solution is not completely separated and removed. This is because the sulfide added in the sulfide precipitation treatment step acts as a reducing agent in that step. It is assumed that the oxygen supplied by air aeration is consumed by this reducing agent, and the oxygen content is insufficient depending on the air aeration rate, leaving residual iron components in the treated solution. It should be noted that if air aeration is continued, the sulfide becomes sulfate ions, and the solution eventually becomes an oxidizing atmosphere, and the iron component also precipitates. However, this method results in a longer aeration time, which is not practical.

[0187] Therefore, in the oxidation treatment step (A), after air aeration, as a final oxidation treatment, it is preferable to further add an oxidant. The amount of oxidant added is preferably adjusted by measuring the redox potential (vs. SHE) to be 550 mV or higher. Suitable examples of oxidants include hydrogen peroxide and potassium permanganate.

[0188] It should be noted that if the oxidation process is carried out after a suitable storage period following the zinc removal process, a final oxidation treatment is not required; air aeration alone is sufficient to allow the iron components to precipitate fully. This is believed to be because hydrogen sulfide, a reducing agent, from the third solution produced in the preceding sulfide precipitation process escapes into the air, making the third solution more susceptible to oxidation and causing a rise in the redox potential. The suitable storage period varies depending on the storage conditions, such as whether it is a closed or open system, and cannot be generalized; it is estimated to be from a few days to about one week.

[0189] Furthermore, in the iron removal process of step (A), the mixture obtained in the above-mentioned oxidation treatment process is separated into a fourth solution and an iron-containing precipitate to remove the iron component. In this way, a high-purity manganese-containing solution (the fourth solution) can be recovered.

[0190] There are no particular restrictions on the separation method; the solid-liquid separation process described above can be followed.

[0191] Iron removal process (step B)

[0192] Next, in the iron removal process of step (B), the second leachate obtained in the solid-liquid separation process is first subjected to an oxidation treatment. In this oxidation treatment, the second leachate is oxidized, causing iron ions contained in the second leachate to precipitate as iron-containing precipitates, thus removing iron components from the second leachate first. Through this treatment, a mixture of a third solution containing manganese and zinc ions and the iron-containing precipitate is obtained from the second leachate.

[0193] Common oxidation methods can be used as oxidation treatment methods, but in this embodiment, air aeration alone is sufficient as an inexpensive oxidation treatment method. From an economic point of view, the air aeration conditions are preferably set to typical practical conditions (blowing rate: 0.1 to 1 times the amount of leachate) / minute, aeration time: 15 to 60 minutes). It should be noted that an oxidant can be added as a final oxidation treatment.

[0194] It should be noted that the oxidation treatment is preferably performed by adjusting the pH of the second leachate using a pH adjuster. If the pH of the second leachate is below 3, iron is difficult to precipitate. On the other hand, if the pH of the second leachate is above 7, manganese is also prone to precipitate. Therefore, the second leachate is preferably adjusted to a pH range of 3 to 7. More preferably, the second leachate is at or above pH 5, more preferably below pH 6, and even more preferably around pH 5 to pH 6. This allows for the suppression of manganese precipitation while ensuring that iron can be precipitated and separated from the second leachate, thereby achieving a high-purity manganese-containing solution with low impurities and a high yield.

[0195] Next, in the iron removal step (B), the mixture obtained in the above-mentioned oxidation treatment step is separated into a third solution containing manganese and zinc ions and an iron-containing precipitate that may mainly contain ferric hydroxide. Thus, iron can be easily separated and removed from the mixture after the oxidation treatment step, and a third solution containing manganese and zinc can be obtained.

[0196] There are no particular restrictions on the separation method; the solid-liquid separation process described above can be followed.

[0197] Zinc removal process (Step B)

[0198] In step (B), a zinc removal process is performed after the aforementioned iron removal process. In the zinc removal process of step (B), the third solution obtained in the previous iron removal process is reacted with sulfides. The zinc ions, predominantly zinc ions in this third solution, precipitate as zinc sulfides, thus removing residual zinc components from the third solution. Through this treatment, a mixture of a high-purity fourth solution (manganese-containing solution) containing manganese ions and the zinc-containing precipitate is obtained from the third solution.

[0199] The third solution separated in the previous iron removal process contains manganese ions and residual zinc ions. If the third solution reacts with sulfides, the zinc component selectively precipitates as sulfides, following the same mechanism as the sulfide precipitation treatment in step (A) above. Then, by adjusting the amount of sulfide added, the concentration of sulfide ions, and the pH of the third solution, the concentration of zinc ions in the third solution can be easily reduced to below the analytical limit (0.1 mg / L).

[0200] The type of sulfide and the preferred pH of the third solution can be determined according to the preferred type of sulfide and the pH of the second leachate in the sulfide precipitation treatment of step (A) above. The pH of the third solution is particularly preferably pH: 4.

[0201] Furthermore, the amount of sulfide that plays a role is preferably 1.1 equivalents or more, more preferably 2 equivalents or more, and most preferably 5 equivalents or less, based on the amount of sulfur in dissolved zinc. When the amount of sulfide that plays a role is less than 1.1 equivalents, although zinc precipitation and removal occur, it is incomplete, and the final removal rate is unstable. If the amount of sulfide that plays a role is 2 equivalents or more, the precipitation and removal of zinc also becomes significant. In addition, if the amount of sulfide that plays a role exceeds 5 equivalents, the amount of sulfide that plays a role becomes excessive, and manganese may also precipitate and be removed.

[0202] Furthermore, in the zinc removal process of step (B), the mixture obtained in the above-mentioned sulfide precipitation treatment process is separated into a fourth solution and a zinc-containing precipitate containing the main zinc sulfide precipitate, thus removing the zinc component. This also removes residual zinc, enabling the simple and high-yield recovery of a high-purity solution containing only manganese.

[0203] As described above, if the third solution contains a large amount of zinc ions, a large amount of fine zinc-containing precipitate is generated during the sulfide precipitation process, thus promoting manganese co-precipitation and reducing the final manganese yield. Furthermore, the zinc separation process becomes difficult due to clogging of the filter cloth during subsequent solid-liquid separation. However, in this invention, the acid-oxidant treatment process prior to the sulfide precipitation process removes most of the zinc from the powder while retaining the manganese, effectively preventing surface manganese co-precipitation and improving the final manganese yield. Additionally, the amount and quality of the zinc-containing precipitate can be controlled, allowing for a simple and efficient zinc separation process.

[0204] There are no particular restrictions on the separation method; the solid-liquid separation process described above can be followed.

[0205] By sequentially going through the above-mentioned processes, carbon, zinc, and iron components, except for manganese, contained in waste dry batteries can be almost completely separated and removed. This allows for the high-purity manganese-containing solution, which reduces zinc and iron content to below the analytical limit, to be recycled with a high yield.

[0206] It should be noted that the obtained manganese-containing solution can be used as a high-purity manganese hydroxide for various applications, for example, as an alkaline precipitate. Furthermore, the obtained manganese-containing solution can be used as a material for secondary battery electrode materials after being mixed with other metals such as nickel and subjected to alkaline precipitation treatment.

[0207] (Manganese recovery equipment)

[0208] Next, the manganese recovery equipment of the present invention will be described. The recovery equipment of the present invention sequentially comprises a sorting device, a crushing device, a screening device, an acid / oxidant treatment tank, a first solid-liquid separation device, an acid / reducing agent treatment tank, a second solid-liquid separation device, and a manganese extraction device assembly, and has the same features and effects as the manganese recovery method of the present invention. Furthermore, the manganese extraction device assembly includes, in different orders, a predetermined zinc removal device assembly and an iron removal device assembly.

[0209] Furthermore, the manganese recovery equipment of the present invention can be appropriately utilized, for example, when implementing the manganese recovery method of the present invention.

[0210] Composition A

[0211] As one aspect of the recycling device of the present invention. Figure 7 The configuration (A) that enables the appropriate implementation of step (A) described above is shown. For example... Figure 7 As schematically shown, the recovery equipment, from upstream to downstream, includes a sorting device 10, a crushing device 20a, a screening device 20b, an acid-oxidant treatment tank 30, a first solid-liquid separation device 40, an acid-reducing agent treatment tank 50, a second solid-liquid separation device 60, a sulfide precipitation treatment tank 70, a zinc separation device 80, an oxidation treatment tank 90, an iron separation device 100, and a manganese-containing solution recovery tank 150. Here, the sulfide precipitation treatment tank 70 and the zinc separation device 80 constitute a zinc removal unit group, and the oxidation treatment tank 90 and the iron separation device 100 constitute an iron removal unit group. Furthermore, the zinc removal unit group and the iron removal unit group constitute a manganese extraction unit group.

[0212] In the sorting device 10, one or both of manganese dry cell batteries and alkaline manganese dry cell batteries are separated from the waste dry cell batteries. The type of sorting device is not particularly limited; devices that utilize shape, radiation, etc., for sorting can be appropriately exemplified. It should be noted that the sorting of waste dry cell batteries can be done manually.

[0213] The crushing device 20a can use any conventional crusher, but it is preferred to use a twin-shaft rotary crusher.

[0214] The screening device 20b preferably has a screen with a mesh size of 1 mm or 20 mm. For the same reasons as described above for the manganese recovery method, the mesh size of the screening device 20b is generally preferably 1 mm or more, preferably 20 mm or less, more preferably 10 mm or less, and even more preferably 3 mm or less.

[0215] The acid-oxidant treatment tank 30 and the acid-reducing agent treatment tank 50 respectively mix the powder with acid solution and oxidant, and mix the first leaching residue with acid solution and reducing agent to carry out leaching reactions. Therefore, it is preferable to make them into general stirred tanks equipped with a stirrer in the tank. When using gases such as oxygen and ozone as oxidants, it is preferable to also provide a gas dispersing device for circulating the oxidant in the tank.

[0216] The sulfide precipitation treatment tank 70 is used to perform sulfide treatment, in which the sulfide reacts with the second leachate. Therefore, it is preferably a general stirred tank equipped with a stirrer inside the tank. In addition, it is preferable to further include a pH adjusting device that allows the addition of a pH adjusting agent to adjust the pH of the second leachate.

[0217] Furthermore, since the third solution is oxidized in the oxidation treatment tank 90, a general stirred tank equipped with a stirrer is preferred. Additionally, a pH adjusting device is preferred, which allows for the adjustment of the pH of the third solution by adding a pH adjusting agent.

[0218] The first solid-liquid separation device 40, the second solid-liquid separation device 60, the zinc separation device 80, and the iron separation device 100 can all be, for example, devices selected from gravity sedimentation separation devices, filtration devices, centrifugal separation devices, filter press devices, membrane separation devices, etc. It should be noted that each separation device preferably includes a recovery tank 110, 120, 130, or 140 capable of recovering the precipitates, etc., separated by solid-liquid separation.

[0219] The manganese solution recovery tank 150 is preferably configured to recover and store the manganese solution (fourth solution) separated by the iron separation device 100 and to be able to be discharged freely.

[0220] Composition of B

[0221] In addition, other methods of the recycling device of the present invention, Figure 8 The configuration (B) is shown to be suitable for carrying out the above-described step (B). For example... Figure 8 As illustrated, the recovery equipment, from upstream to downstream, includes a sorting device 10, a crushing device 20a, a screening device 20b, an acid / oxidant treatment tank 30, a first solid-liquid separation device 40, an acid / reducing agent treatment device 50, a second solid-liquid separation device 60, an oxidation treatment tank 71, an iron separation device 81, a sulfide precipitation treatment tank 91, a zinc separation device 101, and a manganese-containing solution recovery tank 150. Here, the oxidation treatment tank 71 and the iron separation device 81 constitute an iron removal unit group, and the sulfide precipitation treatment tank 91 and the zinc separation device 101 constitute a zinc removal unit group. Furthermore, the iron removal unit group and the zinc removal unit group constitute a manganese extraction unit group.

[0222] Here, the sorting device 10, the crushing device 20a, the screening device 20b, the acid-oxidizing agent treatment tank 30, the first solid-liquid separation device 40, the acid-reducing agent treatment tank 50, the second solid-liquid separation device 60, the iron separation device 81, the zinc separation device 101, the recovery tanks 110, 120, 130, 140, and the manganese-containing solution recovery tank 150 are all as described above for component A.

[0223] The second leachate is oxidized in oxidation treatment tank 71, so it is preferably a general stirred tank equipped with a stirrer inside the tank. In addition, it is preferable to further include a pH adjusting device that can adjust the pH of the second leachate by adding a pH adjusting agent.

[0224] Furthermore, since the sulfide precipitation treatment tank 91 performs sulfide precipitation treatment by reacting the sulfide with the third solution, it is preferably a general stirred tank equipped with a stirrer inside the tank. Additionally, it is preferable to further include a pH adjusting device that allows the addition of a pH adjusting agent to adjust the pH of the third solution.

[0225] It should be noted that in this invention, the various devices, reaction tanks, and recycling tanks constituting the recycling equipment are not limited in structure, as long as they have the above-mentioned functions.

[0226] Example

[0227] The present invention will now be further described based on embodiments. It should be noted that the following embodiments represent preferred examples of the present invention, and the present invention is not limited thereto. Furthermore, the following embodiments may also be implemented with modifications suitable to the spirit of the present invention, and such modifications are also included within the technical scope of the present invention.

[0228] (Example 1)

[0229] Powder preparation

[0230] A sorting process is implemented to separate manganese dry cell batteries and alkaline manganese dry cell batteries from waste dry cell batteries. A crushing and sieving process is then performed to obtain waste dry cell battery powder particles by crushing the sorted waste dry cell batteries and sieving them using a 2.8mm mesh sieve. The main chemical composition of the obtained powder particles (before the acid / oxidant treatment process) is shown in Table 1. It should be noted that, in addition to the elements shown in Table 1, the obtained powder particles also contain oxygen from oxides or hydroxides, some hydrogen, and water.

[0231] Here, in Experiment (A) and Example 1 above, the results of the chemical composition of the powder particles before the acid-oxidant treatment process are the same, so both results are shown in Table 1.

[0232] Acid and oxidant treatment process

[0233] The obtained powder particles were fed into an acid-oxidant treatment tank 30 for acid-oxidant treatment. In this process, 300 mL of acid solution and 80 mL of sodium hypochlorite solution (as an oxidant) were mixed with 30 g of the powder particles, and zinc was primarily leached from the powder particles. The acid concentration of the acid solution was 2N (approximately 8.7% by mass). It should be noted that the acid leaching time was 1 hour, and the leaching was performed with stirring. Under these conditions, the ratio of powder particles to acid solution (solid-liquid ratio) was 100 g / L, and the amount of oxidant added was 26.7% by mass of the amount of acid solution added.

[0234] First solid-liquid separation process

[0235] After the acid and oxidant treatment process, the mixture of the first leachate and the first leaching residue is loaded into the first solid-liquid separation device 40 and filtered using 1 μm pore size filter paper for solid-liquid separation. The concentrations (mass%) of manganese, zinc, and iron in the obtained first leaching residue are quantified by ICP emission spectroscopy. The yield of manganese from the powder to the first leaching residue is as high as 99.99%. The results are recorded in Table 1.

[0236] Here, the results of the chemical composition of the first leaching residue after the acid-oxidant treatment process in Experiment (A) and Example 1 above are the same, so the two results are shown together in Table 1.

[0237] Acid-reducing agent treatment process

[0238] The first leaching residue obtained from the first solid-liquid separation process, along with 2N sulfuric acid (approximately 8.7% by mass) as the acid solution and a 30% hydrogen peroxide solution as the reducing agent, are added to an acid-reducing agent treatment tank 50 and stirred for 1 hour. The solid-liquid ratio (first leaching residue / acid solution) is 50 g / L.

[0239] Second solid-liquid separation process

[0240] The mixture of the second leachate and the second leachate residue was placed in the second solid-liquid separation device 60 and filtered using 1 μm pore size filter paper for solid-liquid separation. The concentrations (mg / L) of manganese, zinc, and iron in the second leachate obtained after the second solid-liquid separation process were quantified using ICP emission spectroscopy. The results are presented in Table 2, "Second Leachate After the Second Solid-Liquid Separation Process".

[0241] Preparation of the third solution (zinc removal process)

[0242] Next, the second leachate obtained from the second solid-liquid separation process is placed in a sulfide precipitation treatment tank 70 for a sulfide precipitation treatment process, where the zinc components still remaining in the second leachate react with the sulfides. In the sulfide precipitation treatment process, sodium hydrosulfide is added to the second leachate as a sulfide at a ratio of 2 equivalents to dissolved zinc sulfide. It should be noted that the sodium hydrosulfide is added in a solution dissolved in distilled water. Furthermore, the pH of the second leachate in the sulfide precipitation treatment is adjusted to 4 using a pH adjusting solution (3M sulfuric acid or 100 g / L sodium hydroxide). The sulfide precipitation treatment is carried out for 30 minutes with stirring.

[0243] The mixture after the above-described sulfide precipitation treatment process was loaded into a zinc separation device 80, and a zinc separation process was performed using filter paper with a pore size of 1 μm for solid-liquid separation, separating the solids into a third solution and a zinc-containing precipitate. Here, the filtration time required in conventional zinc separation processes is approximately 35 minutes, but in this embodiment, where the powder particles have undergone a pre-treatment with an acid and oxidant, this time is shortened to approximately 15 minutes. Furthermore, the composition of the obtained third solution was quantitatively analyzed by ICP emission spectroscopy. It should be noted that the amounts of sodium hydrosulfide solution and pH adjuster added were recorded, and the effects of dilution with these solutions were corrected based on the analytical values. The results are recorded together in Table 2, "Third Solution after Zinc Removal Process".

[0244] Preparation of the fourth solution (iron removal process)

[0245] Next, the third solution obtained from the zinc removal process was placed into the oxidation treatment tank 90 for oxidation treatment. In the oxidation treatment process, the obtained third solution was first aerated with air. The air aeration conditions were: airflow rate (same as the volume of the third solution) / minute, and aeration time: 30 minutes. After air aeration, the components contained in the intermediate solution, which was filtered using 1 μm filter paper, were quantitatively analyzed using the above method. The results are recorded in Table 2, "Intermediate Solution After Oxidation Treatment".

[0246] Next, as a further oxidation treatment, an oxidant was immediately added to the third solution after air aeration. During the addition of the oxidant, a pH adjusting solution (3M sulfuric acid or 100g / L sodium hydroxide) was added to adjust the pH of the third solution to 5, and then approximately 8–16 mL of hydrogen peroxide solution was added as the oxidant to raise the redox potential to above 550mV. This precipitates the iron component in the third solution as ferric hydroxide, making it removable. It should be noted that the treatment time based on the oxidant was 30 minutes.

[0247] The mixture obtained after the oxidation treatment process by air aeration and oxidant addition is loaded into the iron separation device 100 and filtered by vacuum using filter paper with a pore size of 1μm to carry out the iron separation process of solid-liquid separation into a manganese-containing solution (fourth solution) and an iron-containing precipitate.

[0248] The components in the obtained fourth solution were quantitatively analyzed using the method described above. It should be noted that the amounts of hydrogen peroxide solution and pH adjuster added were recorded, and the effects of dilution by these solutions were corrected for based on the analytical values. The results are recorded together in Table 2, "Fourth Solution after Iron Removal Process". The manganese yield in the obtained fourth solution (containing manganese ions) was 99%.

[0249] Table 2]

[0250]

[0251] As shown in Table 2, step A, which is an embodiment of the manganese recovery method of the present invention, can easily separate and remove zinc and iron components other than manganese from waste dry batteries to below the analytical limit (0.1 mg / L). Thus, it can be seen that according to the present invention, manganese components contained in waste dry batteries can be easily and effectively recovered with a high yield as a high-purity manganese ion solution.

[0252] (Example 2)

[0253] The powder particles were prepared in the same manner as in Example 1, and the powder particles with the composition shown in Table 1 were obtained. In addition, the acid-oxidizing agent treatment process, the first solid-liquid separation process, the acid-reducing agent treatment process, and the second solid-liquid separation process were performed in the same manner as in Example 1. The results show the content (mg / L) of each component of manganese, zinc, and iron in the second leachate after the second solid-liquid separation process as shown in Table 3.

[0254] Next, the third solution (zinc removal process) was prepared in the same manner as in Example 1, and the composition of the third solution after the zinc removal process is shown in Table 3. It should be noted that the existing zinc separation process requires a filtration time of approximately 35 minutes, but in the zinc separation process of this embodiment, where the powder particles have undergone a pre-treatment with an acid and oxidant, this time is shortened to approximately 25 minutes.

[0255] Next, the third solution obtained from the zinc separation process was left to stand at room temperature for one week before being placed in oxidation treatment tank 90 for oxidation treatment. During the oxidation treatment, the third solution after standing was subjected to air aeration only. The air aeration conditions were: airflow rate (same as the volume of the third solution) / min, and aeration time: 30 minutes. After air aeration, the manganese-containing solution (fourth solution) filtered using 1 μm filter paper was quantitatively analyzed for its components using the method described above. The results are recorded in Table 3, "Fourth Solution after Iron Removal Process". The yield of manganese in the obtained fourth solution (manganese ion-containing solution) exceeded 99%.

[0256] [Table 3]

[0257]

[0258] As shown in Table 3, in step A, which is one embodiment of the manganese recovery method of the present invention, if the third solution separated by sulfide precipitation is subjected to an oxidation treatment after a suitable settling period, the iron component can be sufficiently separated and removed as a precipitate simply by using air aeration for oxidation treatment. As a result, manganese can be recovered with a high yield.

[0259] (Example 3)

[0260] The powder particles were prepared in the same manner as in Example 1, resulting in powder particles with the composition shown in Table 1. Furthermore, the acid-oxidizing agent treatment step, the first solid-liquid separation step, the acid-reducing agent treatment step, and the second solid-liquid separation step were performed in the same manner as in Example 1. The results show the content (mg / L) of manganese, zinc, and iron in the second leachate after the second solid-liquid separation step, as shown in Table 4.

[0261] Preparation of the third solution (iron removal process)

[0262] Next, the second leachate separated in the second solid-liquid separation step undergoes an oxidation treatment process. In this oxidation treatment, the resulting second leachate is aerated with air, generating ferric hydroxide from the iron components contained within it. This removes the iron components from the second leachate as an iron-containing precipitate. The air aeration conditions are: airflow rate (same as the volume of the second leachate, mL) / min, aeration time: 30 minutes. It should be noted that during the oxidation treatment, the pH of the second leachate is adjusted to 5 using a pH adjuster (3M sulfuric acid or 100 g / L sodium hydroxide).

[0263] After oxidation treatment, the third solution and the iron-containing precipitate were separated by filtration using 1 μm filter paper (iron separation step). Then, ICP emission spectroscopy was used to quantitatively analyze the components (manganese, zinc, and iron) in the third solution obtained from the iron removal step. It should be noted that the amount of pH adjuster added should be recorded to correct for the effect of dilution with pH adjuster on the measured values. The concentrations (mg / L) of each component (manganese, zinc, and iron) in the obtained third solution are recorded in Table 4, "Third Solution After Iron Removal Step".

[0264] Preparation of the fourth solution (zinc removal process)

[0265] Next, a sulfide precipitation process is performed: the third solution separated in the iron separation process reacts with the sulfide, causing the zinc ions still mainly remaining in the third solution to precipitate as zinc sulfide (zinc-containing precipitate), making it removable from the third solution. Sodium hydrosulfide is used, added at a sulfur equivalent of 2 equivalents relative to the dissolved zinc. It should be noted that sodium hydrosulfide is added in a solution dissolved in distilled water. Furthermore, the pH of the third solution in the sulfide precipitation process is adjusted to 4 using a pH adjusting solution (3M sulfuric acid or 100 g / L sodium hydroxide). The sulfide precipitation process is carried out for 30 minutes with stirring.

[0266] The mixture after sulfide precipitation was filtered using 1 μm pore size filter paper to separate a manganese-containing solution (fourth solution) and a zinc-containing precipitate (zinc separation step). While existing zinc separation steps require approximately 35 minutes of filtration time, this example, which pre-treated the powder with an acid and oxidant, shortens the time to approximately 25 minutes. The composition of the resulting fourth solution was then quantitatively analyzed using ICP emission spectroscopy. It should be noted that the amounts of sodium hydrosulfide solution and pH adjuster added were recorded, and the effects of dilution from these solutions were corrected for based on the measured values. The results are listed in Table 4, "Fourth Solution After Zinc Removal Step". The manganese yield in the obtained fourth solution (manganese ion-containing solution) was 95%.

[0267] Table 4

[0268]

[0269] As shown in Table 4, in one embodiment of the manganese recovery method according to the present invention, namely step B, zinc and iron components other than manganese contained in waste dry batteries can be easily separated and removed to below the analytical limit (0.1 mg / L). Thus, it can be seen that according to the present invention, manganese contained in waste dry batteries can be easily and effectively recovered with a high yield as a high-purity manganese ion-containing solution.

[0270] (Example 4)

[0271] The powder particles were prepared in the same manner as in Example 1. The obtained powder particles were placed in an acid-oxidant treatment tank 30, and the amount of sodium hypochlorite added as the oxidant was varied during the acid-oxidant treatment process. Specifically, 300 mL of acid solution and 0–200 mL of sodium hypochlorite solution were mixed with 30 g of powder particles, and zinc was mainly leached from the powder particles. Other conditions were the same as in Example 1. In this case, the solid-liquid ratio of the powder particles to the acid solution was 100 g / L, and the amount of oxidant added was 0–66.7% by mass of the amount of acid solution added.

[0272] Next, the mixture of the first leachate and the first leachate residue was placed into the first solid-liquid separation device 40 and filtered using 1 μm pore size filter paper for solid-liquid separation. The manganese and zinc concentrations (mg / L) in the obtained first leachate were quantified using ICP emission spectroscopy. The results are shown below. Figure 9 .

[0273] It has been found that by setting the amount of sodium hypochlorite solution added to 60 mL (20% by mass relative to the amount of acid solution added) or more, the amount of manganese dissolved in the first leaching solution can be significantly reduced to about 1 / 5 compared to the case where no sodium hypochlorite solution is added (0% by mass relative to the amount of acid solution added). Furthermore, by setting the amount of sodium hypochlorite solution added to 150 mL (50% by mass relative to the amount of acid solution added) or more, the amount of manganese dissolved in the first leaching solution can be suppressed to less than 1 mg / L, and the yield of manganese from the powder to the first leaching residue can be increased to 99.99%. On the other hand, as... Figure 9 As shown, regardless of the amount of sodium hypochlorite solution added, approximately 20,000 mg / L of zinc dissolved in the first leaching solution. Therefore, it is preferable to control the amount of sodium hypochlorite solution added as an oxidant to be 60 mL (20% by mass relative to the amount of acid solution added) or more, more preferably 150 mL (50% by mass relative to the amount of acid solution added), to selectively remove zinc and ensure the manganese content in the first leaching residue with a high yield, thereby enabling the recovery of manganese with a high yield.

[0274] Symbol Explanation

[0275] 10: Sorting device

[0276] 20a: Crushing device

[0277] 20b: Screening device

[0278] 30: Acid and Oxidant Treatment Tank

[0279] 40: First solid-liquid separation device

[0280] 50: Acid-Reducing Agent Treatment Tank

[0281] 60: Second solid-liquid separation device

[0282] 70: Sulfide precipitation treatment tank (Component A)

[0283] 71: Oxidation treatment tank (Component B)

[0284] 80: Zinc separation device (Component A)

[0285] 81: Iron separation device (component B)

[0286] 90: Oxidation treatment tank (Component A)

[0287] 91: Sulfide Precipitation Treatment Tank (Component B)

[0288] 100: Iron separation device (Component A)

[0289] 101: Zinc separation unit (Component B)

[0290] 110: Recycling Tank

[0291] 120: Recycling Tank

[0292] 130: Recycling Tank

[0293] 140: Recycling Tank

[0294] 150: Manganese-containing solution recovery tank

Claims

1. A method for recovering manganese contained in waste dry cell batteries, comprising the following steps: The sorting process separates waste dry cell batteries into one or both of manganese dry cell batteries and alkaline manganese dry cell batteries. The crushing and sieving process involves crushing and sieving one or both of the manganese dry cell batteries and alkaline manganese dry cell batteries separated in the sorting process to obtain powder or granules. In the acid-oxidizing agent treatment step, an acid solution and an oxidizing agent are mixed with the powder particles obtained in the crushing and sieving step to leach zinc while inhibiting manganese leaching, resulting in a first leaching solution and a first leaching residue. In the first solid-liquid separation step, the first leachate and the first leachate residue obtained in the acid-oxidant treatment step are separated. In the acid-reducing agent treatment step, an acid solution and a reducing agent are mixed in the first leaching residue separated in the first solid-liquid separation step to obtain a second leaching solution and a second leaching residue. The second solid-liquid separation process separates the second leachate and the second leachate residue obtained in the acid-reducing agent treatment process. In the manganese extraction process, the zinc ions and iron ions contained in the zinc ions, iron ions and manganese ions in the second leachate separated in the second solid-liquid separation process are removed to obtain a solution containing the manganese ions. The manganese extraction process includes zinc removal and iron removal processes in different sequences. The zinc removal process includes a sulfide precipitation treatment process in which the zinc ions are precipitated by reacting the sulfide with the zinc ions, and a zinc separation process in which the zinc-containing precipitate is further separated. The iron removal process includes an oxidation treatment process that oxidizes the iron ions to precipitate them, and an iron separation process that further separates the resulting iron-containing precipitate. The oxidant in the acid-oxidant treatment process is any one of sodium hypochlorite solution, oxygen, or potassium permanganate solution.

2. The recycling method according to claim 1, wherein, The acid solution in the acid-oxidant treatment process is dilute sulfuric acid with a mass concentration of 1.4% to 45% or dilute hydrochloric acid with a mass concentration of 1% to 14%.

3. The recycling method according to claim 1 or 2, wherein, The solid-liquid ratio of the powder to the acid solution in the acid-oxidant treatment process is 50 g / L or higher.

4. The recycling method according to claim 1 or 2, wherein, The acid solution in the acid-reducing agent treatment process is dilute sulfuric acid with a mass concentration of 1.4% to 45% or dilute hydrochloric acid with a mass concentration of 1% to 14%.

5. The recycling method according to claim 1 or 2, wherein, The reducing agent in the acid-reducing agent treatment process is any one of hydrogen peroxide, sodium sulfide, sodium bisulfite, sodium thiosulfate, and ferric sulfate.

6. The recycling method according to claim 1 or 2, wherein, The manganese extraction process is performed in the order of the zinc removal process followed by the iron removal process. In the zinc removal process, after the sulfide precipitation treatment step, in which the sulfide reacts with the second leaching solution to precipitate zinc ions in the second leaching solution, a zinc separation step is performed to separate the obtained zinc-containing precipitate with a third solution containing manganese and iron ions. In the iron removal process, after the oxidation treatment process in which the third solution obtained in the zinc removal process is oxidized to precipitate iron ions in the third solution, an iron separation process is performed to separate the iron-containing precipitate and the fourth solution containing manganese ions into solid and liquid components.

7. The recycling method according to claim 6, wherein, In the sulfide precipitation treatment process, the second leachate is adjusted to pH 2-6.

8. The recycling method according to claim 6, wherein, In the oxidation treatment process, the third solution containing manganese ions and iron ions is aerated with air, or an oxidant is further added to the third solution, and the pH of the third solution is adjusted to 3-7.

9. The recycling method according to claim 1 or 2, wherein, The manganese extraction process is performed in the order of the iron removal process followed by the zinc removal process. In the iron removal process, after the oxidation treatment process of oxidizing the second leachate to precipitate the iron ions in the second leachate, an iron separation process is performed to separate the obtained iron-containing precipitate from the iron in a third solution containing manganese and zinc ions. In the zinc removal process, after the sulfide precipitation treatment process in which the sulfide reacts with the third solution obtained in the iron removal process to precipitate zinc ions in the third solution, a zinc separation process in which the obtained zinc-containing precipitate is separated from the fourth solution containing manganese ions is carried out.

10. The recycling method according to claim 9, wherein, In the sulfide precipitation process, the third solution containing manganese and zinc ions is adjusted to a pH of 2-6.

11. The recycling method according to claim 9, wherein, In the oxidation treatment process, the second leachate is aerated with air and the pH of the second leachate is adjusted to 3-7.

12. The recycling method according to claim 1 or 2, wherein, The sulfide used in the sulfide precipitation process is any one of sodium hydrosulfide, sodium sulfide, and hydrogen sulfide.

13. A device for recovering manganese contained in waste dry-cell batteries, comprising the following components: The sorting device separates one or both of manganese dry cell batteries and alkaline manganese dry cell batteries from waste dry cell batteries. A pulverizing device is used to pulverize one or both of the manganese dry cell batteries and alkaline manganese dry cell batteries that have been separated by the sorting device, to obtain pulverized material. A sieving device performs a sieving process on the pulverized material obtained by the pulverizing device to obtain powder particles. An acid-oxidizing agent treatment tank is used to treat the powder particles obtained in the screening device with an acid solution and an oxidizing agent, thereby leaching zinc while inhibiting manganese leaching. The first solid-liquid separation device separates the first leachate and the first leachate residue obtained from the acid-oxidant treatment tank. An acid-reducing agent treatment tank is used to treat the first leaching residue separated by the first solid-liquid separation device with an acid solution and a reducing agent. The second solid-liquid separation device separates the second leachate and the second leachate residue obtained from the acid-reducing agent treatment tank, and The manganese extraction apparatus removes zinc ions and iron ions from the second leachate separated by the second solid-liquid separation apparatus, thereby obtaining a solution containing the manganese ions. The manganese extraction unit group includes a zinc removal unit group and an iron removal unit group in different orders. The zinc removal unit includes a sulfide precipitation tank for reacting sulfides with zinc ions to precipitate the zinc ions, and a zinc separation unit for further solid-liquid separation of the obtained zinc-containing precipitate. The iron removal device group includes an oxidation treatment tank for oxidizing the iron ions to precipitate them, and an iron separation device for further solid-liquid separation of the obtained iron-containing precipitate. The oxidant in the acid-oxidant treatment tank is any one of sodium hypochlorite solution, oxygen, or potassium permanganate solution.

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