JPH0733442A - Production of mn-zn ferrite - Google Patents

Abstract

PURPOSE:To produce Mn-Zn ferrite powder excellent in magnetic characteristics without causing pollution by mercury while using a waste alkali-manganese dry cell as starting material. CONSTITUTION:A waste alkali-manganese dry cell is dissolved in an acidic aq. soln. contg. hydrogen peroxide, metal iron is added to the resulting soln. to deposit mercury by reduction and this mercury is separated and removed. The mercury-free aq. soln. is then made alkaline to coprecipitate Mn, Zn and Fe dissolved as ions in the aq. soln. as hydroxides and Mn-Zn ferrite is obtd. by oxidizing the hydroxides. At this time, the concn. of each of the Mn, Zn and Fe in the aq. soln. is regulated before coprecipitation so as to obtain the objective Mn-Zn ferrite having satisfactory magnetic characteristics. The oxidation of a mixture of the hydroxides is carried out by allowing the hydroxides to react with a chlorate in the aq. soln.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to recycling or recycling of used or discarded alkaline manganese dry batteries, that is, waste alkaline manganese dry batteries. More specifically, it relates to a method for producing Mn-Zn ferrite from iron, zinc and manganese contained in a waste alkaline manganese dry battery.

[0002]

2. Description of the Related Art In recent years, global awareness of global environmental problems has increased, and there is a demand for effective use of resources, that is, recycling of industrial waste, which is rapidly increasing. In this regard, alkaline manganese primary dry batteries, which are widely used as a simple and inexpensive power source at present, are no exception, and it is desirable to reuse manganese dioxide, zinc, etc. contained in large quantities in them as resources. It is rare.

By the way, there is known a method in which zinc and manganese are directly recovered by a metallurgical process from a general waste manganese dry battery using zinc chloride without using caustic potash or the like as an electrolytic solution. In this method, a waste manganese dry battery is first crushed and heated to 500 ° C. or higher to decompose and vaporize mercury and a mercury compound. In this case, zinc and zinc chloride have relatively low boiling points, but if kept in an oxidizing atmosphere, their evaporation can be suppressed. Next, coke is added as a reducing agent to the waste manganese dry battery from which mercury has been removed as described above, and is subjected to smelting reduction at 1,400 to 1,500 ° C., whereby zinc is reduced and vaporized and recovered, and manganese and iron Is recovered as an alloy (ferro-manganese).

Further, in order to recycle the waste manganese dry battery, it is powder metallurgically used as one of the raw materials for Mn-Z.
A method for producing an n-ferrite sintered body has been proposed (J. IEEE Japan, 110 (6), 502 (1
990)). In this method, the soot-burning residue containing a large amount of zinc oxide and manganese oxide obtained when recovering mercury from a waste manganese dry battery by the soot-burning method is used as a raw material for zinc and manganese. Using iron-containing sludge and iron-containing waste (recovered powder) from the iron mining industry, etc., obtained by subjecting wastewater containing heavy metals generated from etc. to ferritization, according to a general powder metallurgy process First, each waste is processed into powder and used as raw material. The metal content of each powder raw material is determined, and then each raw material is weighed so as to have a predetermined sintered body composition and mixed using a ball mill. After that, the mixed raw material is press-molded into an appropriate shape and fired using a butane gas furnace to obtain Mn-
A Zn ferrite is manufactured.

It is considered that these methods are similarly applicable to the case of recycling alkaline manganese dry batteries.

[0006]

However, when the waste alkaline manganese dry battery is to be recycled, the most problematic is the treatment of harmful mercury contained in the composition.
There is a problem that mercury cannot always be completely removed by recycling using the above-mentioned conventional thermometallurgical method or powder metallurgical method. Therefore, when Mn-Zn ferrite is manufactured from a waste alkaline manganese dry battery, a problem of mercury contamination occurs.

For this reason, although an alkaline manganese dry battery which does not use mercury has been developed, mercury is practically completely separated and removed from the enormous amount of alkaline manganese dry batteries that have been produced so far. It is desired to be able to recycle.

[0008] The present invention is intended to solve the above-mentioned problems of the prior art, and to make it possible to separate mercury from waste alkaline manganese dry batteries and to produce Mn-Zn ferrite by a simple operation. To aim.

[0009]

The present inventor has proposed that manganese,
By adding metallic iron to an acidic aqueous solution in which zinc, iron and mercury are dissolved, mercury can be reduced and precipitated and easily separated, and manganese is obtained by making the acidic aqueous solution from which mercury is separated alkaline. The inventors have found that Mn-Zn ferrite can be easily produced by a simple operation by co-precipitating hydroxides of zinc and iron and oxidizing the hydroxides, and completed the present invention.

That is, the present invention relates to a method for producing Mn-Zn ferrite from a waste alkaline manganese dry battery:
First step of dissolving a waste alkaline manganese dry battery in an acidic aqueous solution containing hydrogen peroxide; mercury is reduced and deposited by adding metallic iron to the aqueous solution obtained in the first step,
Second step of separating and removing the mercury; by making the aqueous solution obtained in the second step alkaline, Mn, Zn and Fe dissolved as ions in the aqueous solution are co-precipitated as hydroxides, Mn, Third step of obtaining a hydroxide mixture of Zn and Fe; and Mn, Zn obtained in the third step
And a fourth step of obtaining Mn-Zn ferrite by oxidizing Fe hydroxide.

The present invention will be described in detail below.

As described above, the present invention is basically 4
The first step is a step of dissolving the waste alkaline manganese dry battery in an acidic aqueous solution containing hydrogen peroxide. The first step is a step for dissolving manganese dioxide, zinc, iron and mercury used in a waste alkaline manganese dry battery and removing insoluble materials such as plastics and carbon rods. Therefore, it is preferable to filter the insoluble matter from the solution after the dry cell is dissolved.

Further, it is preferable to remove the hydrogen peroxide remaining in the solution from which the insoluble matter is filtered out in order to carry out the next step. For that purpose, the solution is heated under reflux to remove hydrogen peroxide. Is preferably decomposed.

As the acidic aqueous solution containing hydrogen peroxide, a solution obtained by adding hydrogen peroxide to an aqueous solution of mineral acid such as hydrochloric acid or sulfuric acid, or a solution obtained by dissolving potassium persulfate as a hydrogen peroxide source in the aqueous solution of mineral acid is used. Can be used. in this case,
The acid strength of the aqueous mineral acid solution is preferably 3N or higher, more preferably 4N or higher. If the acid strength is less than 3 N, the rate of dissolving the dry battery may be slowed down, the dissolution residue may increase, and the dissolution yield may decrease.

In carrying out the second step, generally,
First, an aqueous alkali metal hydroxide solution such as caustic soda is added to the aqueous solution obtained in the first step, and the pH is adjusted to 3 to 5
And then add metallic iron powder thereto with stirring. The reason why metallic iron is used here is to reduce and precipitate mercury. Therefore, ferrous chloride (FeCl ₂ .4H ₂ O) or ferric chloride (FeCl ₃ .6H ₂ O), which cannot reduce and precipitate mercury, cannot be used in the second step.

The deposited mercury can be easily separated and removed by filtering.

In the third step, Mn, Zn and F obtained by making the aqueous solution obtained in the second step alkaline
e co-precipitates as hydroxide. In this case, p of the aqueous solution
It is preferred that H be about 9. For this purpose, it is preferable to add an aqueous solution of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide to the aqueous solution.

In the fourth step, the hydroxide coprecipitated in the third step is oxidized. As a method of oxidation, first, hydroxide may be filtered from the reaction solution obtained in the third step, and then the filtered hydroxide may be calcined in the presence of oxygen. It is preferable to convert to Mn-Zn ferrite by adding a chlorate such as sodium chlorate to a reaction solution containing hydroxide and stirring under reflux without filtering it in advance. Thus, Mn can be easily heated under a mild condition of heating and refluxing in the presence of an oxidizing agent and by a simple operation.
The ability to be converted to —Zn ferrite is extremely advantageous in terms of manufacturing cost, safety, operability, etc., as compared with the conventional thermometallurgical or powder metallurgical methods that require high heat. The Mn-Zn ferrite thus obtained is
The product is obtained by filtering, washing and drying.

The respective contents of manganese, zinc and iron in the waste alkaline manganese dry battery are usually different from the composition ratio of Mn-Zn ferrite having preferable magnetic characteristics. For example, the Mn-Zn ferrite material often used in magnetic heads, transformers, etc., contains 50 to 55 mol% Fe ₂ O ₃ and 20 to 30 mol% MnO and 15 to 50 mol%.
It is composed of 30 mol% ZnO. Therefore, the third
Prior to the step, the concentration of manganese ion, zinc ion and iron ion in the aqueous solution obtained in the second step can be calculated by, for example, Mn.
The molar ratio converted to O, ZnO, and Fe ₂ O ₃ is 28:20.
It is preferable to adjust the pair 52. in this case,
In order to replenish manganese ions, for example, manganese sulfate (MnSO ₄ .5H ₂ 0) is preferably added, and when replenishing zinc ions, for example, zinc sulfate (ZnSO ₄ .7H ₂ 0) is added. It is preferable to add.

When supplementing iron ions, metallic iron, ferrous chloride (FeCl ₂ .4H ₂ O), ferrous sulfate (FeSO ₄ .7H ₂ O) or the like can be used.

[0021]

In the method for producing Mn-Zn ferrite of the present invention, metallic iron is added to the acidic aqueous solution in which manganese, zinc, iron and mercury are dissolved. This makes it possible to reduce and deposit mercury for easy separation. Further, the acidic aqueous solution from which mercury has been separated is made alkaline. This allows manganese, zinc and iron to be coprecipitated as hydroxides. When this coprecipitated hydroxide mixture is oxidized, it can be converted into Mn-Zn ferrite. In particular, Mn-Zn ferrite can be easily obtained by adding a chlorate to a solution containing the hydroxide mixture and heating the mixture to reflux. Can be converted to.

[0022]

The present invention will be described in more detail by the following examples.

Examples 1 to 4 A single type waste alkaline manganese dry battery (LS20, manufactured by Sony Energy Tech Co., Ltd.) was immersed in 1 liter of dilute hydrochloric acid, and 50 ml of hydrogen peroxide solution (30%) was further added. , Dissolvable components of a waste manganese dry battery were dissolved in an acidic aqueous solution.

The acid strength of the dilute hydrochloric acid used was the same as in Example 1.
4 Nos., 6 Nos. In Example 2, 2 Nos. In Example 3, and 3 Nos. In Example 4 were used.

Next, this waste alkaline manganese dry battery dissolved aqueous solution was filtered to remove dissolved residues such as carbon in the carbon rod and the mixture. Further, the filtrate was heated and boiled for 1 hour to decompose and remove excess hydrogen peroxide.

The relationship between the dissolution residue and the acid strength used is shown in FIG. According to this, it was confirmed that the weight of the dissolved residue was saturated when an acid having an acid strength of 4 N or higher was used. Therefore, it was confirmed that in the case of the reaction system of this example, it is preferable to use an acid having an acid strength of 4 N or higher.

Next, sodium hydroxide was added to the resulting aqueous solution to adjust the pH of the solution to 3 to 5, and metallic iron powder was added to reduce and precipitate mercury. Then, the deposited mercury was removed by performing filtration twice.

Next, manganese sulfate (M) whose amount of Mn, Zn and Fe in the reaction solution is 28:20:52 in terms of the molar ratio converted to MnO, ZnO and Fe ₂ O _3.
nSO ₄ · _5H 2 0) and zinc sulfate (ZnSO ₄ · 7H ₂
0) and metallic iron were appropriately dissolved. At this time, the pH of the solution
In order to keep the value within the range of 3 to 5, dilute hydrochloric acid was appropriately added.

Then, an aqueous sodium hydroxide solution was added to the obtained aqueous solution to adjust the pH of the solution to about 9. As a result, M
Hydroxides of n, Zn and Fe co-precipitated. Then, an aqueous potassium chlorate solution was added, and the reaction solution was refluxed (1
The hydroxide was oxidized by stirring at 00 ° C for 1 hour. After completion of the reaction, after thoroughly washing the obtained product with water,
Mn-Zn ferrite fine particle powder was obtained by filtering and drying.

When the obtained Mn-Zn ferrite fine particle powder was subjected to a chemical analysis, no trace of mercury was found in the ferrite powders of Examples 1 to 4.

Further, a sintered body was produced from the Mn-Zn ferrite fine particle powder obtained in Example 1 as described below.

First, the Mn-Zn ferrite fine particle powder was pre-baked at 1000 ° C. in a nitrogen gas atmosphere. Next, this Mn-Zn ferrite fine particle powder is applied with a pressure of 500 kg / cm ^{2 in} the air by a discharge plasma sintering method, and a current of 2000 amperes is supplied to the polycrystalline Mn-Zn-Zn for firing for 2 minutes. A ferrite material was obtained. The polycrystalline Mn-Zn ferrite material thus obtained is annealed (600 ° C. under a nitrogen atmosphere).
I went.

The thus-annealed polycrystalline Mn--
The true density of the Zn ferrite material was 99% or more of the theoretical density, and it was sufficiently densified. Also, this polycrystalline Mn-
A ring molded product (inner diameter 3 mm, outer diameter 6 mm, thickness 1 mm) was manufactured from Zn ferrite material, and the magnetic permeability (μ ′) at a frequency of 1 MHz was measured.
= 1500). Moreover, when the saturation magnetic flux density (Bs) was measured, a high value of Bs = 0.55T was shown. Thus, an excellent Mn-Zn ferrite sintered body could be manufactured from the Mn-Zn ferrite fine particle powder obtained in this example.

Example 5 A single type waste alkaline manganese dry battery (LS20, manufactured by Sony Energy Tech Co., Ltd.) was immersed in 1 liter of 5N dilute hydrochloric acid, and further hydrogen peroxide solution (30%) 10
0 ml was added and the dissolvable components of the waste manganese dry battery were dissolved in the acidic aqueous solution.

Next, the waste alkaline manganese dry battery dissolved aqueous solution was filtered to remove dissolved residues such as carbon in the carbon rod and the mixture. Further, the filtrate was heated and boiled for 1 hour to decompose and remove excess hydrogen peroxide.

Next, sodium hydroxide was added to the obtained aqueous solution to adjust the pH of the solution to 3-5. Mn, Zn and Fe concentrations (MnO, ZnO) in the obtained aqueous solution
And Fe ₂ O ₃ conversion) are shown in Table 1. The mercury concentration was about 0.1 g / lit.

[0037]

[Table 1] To add and dissolve metallic iron powder in this aqueous solution
More mercury was reduced and deposited. Then, do the filtration twice.
The mercury deposited by was removed.

Next, the concentrations of Mn, Zn, and Fe in the reaction solution from which mercury has been removed in this way are determined as MnO and ZnO.
And manganese sulfate (MnSO ₄ .5H ₂ 0), zinc sulfate (ZnSO ₄ .7H ₂ 0) and metallic iron in amounts such that the molar ratio converted to Fe ₂ O ₃ is 28:20:52. It was At this time, in order to keep the pH of the solution within the range of 3 to 5, dilute hydrochloric acid was appropriately added.

Then, an aqueous sodium hydroxide solution was added to the obtained aqueous solution to adjust the pH of the solution to about 9. As a result, M
Hydroxides of n, Zn and Fe co-precipitated. Then, an aqueous potassium chlorate solution was added, and the reaction solution was refluxed (1
The hydroxide was oxidized by stirring at 00 ° C. for 1 hour. After completion of the reaction, the obtained product was thoroughly washed with water and then filtered and dried to obtain Mn-Zn ferrite fine particle powder.

When the obtained Mn-Zn ferrite fine particle powder was subjected to a chemical analysis, there was no trace of mercury in the ferrite powder of this example.

The X-ray diffraction analysis of the Mn-Zn ferrite fine particle powder obtained in this example is shown in FIG. As is clear from the figure, this M
It was confirmed that the n-Zn ferrite fine particle powder was composed of a single spinel phase suitable as a magnetic material.

[0042]

According to the present invention, it is possible to separate and recover mercury in a waste alkaline manganese dry battery by an extremely simple chemical process, and Mn-Zn containing no mercury and having good magnetic characteristics.
Ferrite can be manufactured. Therefore, according to the present invention, the waste alkaline manganese dry battery can be recycled or recycled into Mn-Zn ferrite without causing the problem of mercury contamination.

[Brief description of drawings]

FIG. 1 is a relationship diagram between acid strength and a dissolution residue when a waste alkaline manganese dry battery is dissolved in an acidic aqueous solution.

FIG. 2 is an X-ray diffraction chart of Mn-Zn ferrite powder.

Claims (4)

[Claims] 1. A waste alkaline manganese dry battery to Mn-Z.
In the method for producing n-ferrite: first step of dissolving a waste alkaline manganese dry battery in an acidic aqueous solution containing hydrogen peroxide; reduction of mercury by adding metallic iron to the aqueous solution obtained in the first step A second step of separating and removing the mercury; by making the aqueous solution obtained in the second step alkaline, Mn, Zn and Fe dissolved as ions in the aqueous solution are coprecipitated as hydroxides,
A third step of obtaining a mixture of hydroxides of Mn, Zn and Fe; and a fourth step of oxidizing the hydroxide of Mn, Zn and Fe obtained in the third step to obtain Mn-Zn ferrite A manufacturing method characterized by the above. 2. The method for producing Mn—Zn ferrite according to claim 1, wherein the acid strength of the acidic aqueous solution used in the first step is 4 N or higher. 3. The Mn- according to claim 1, further comprising a step of adjusting the manganese ion, zinc ion and iron ion concentrations in the aqueous solution obtained in the second step, prior to the third step.
Method for producing Zn ferrite. 4. In the fourth step, Mn, Zn and Fe
The M according to any one of claims 1 to 3, which is oxidized by reacting a mixture of the hydroxides of claim 1 with a chlorate in an aqueous solution.
Manufacturing method of n-Zn ferrite.