JPH02145428A - Production of manganese oxide for dry cell - Google Patents

Abstract

PURPOSE:To obtain manganese oxide for dry cells having an extremely low rise in internal resistance, especially in low-rate discharge with remarkably higher activity at a markedly lower cost than those of electrolytic manganese dioxide by subjecting manganese oxide to aluminum treatment under specific pH conditions in the course of a production process for chemical converted manganese dioxide. CONSTITUTION:A manganese oxide is roasted at a higher temperature than decomposition temperature thereof to form manganese oxide consisting essentially of Mn2O3 and/or Mn3O4. The resultant product is then treated with a mineral acid to afford manganese oxide consisting essentially of MnO2. The obtained manganese oxide is subsequently treated in an aqueous medium at pH-2.0-4.0 or >=10 containing an aluminum compound to provide manganese oxide containing >=75% MnO2 and the aluminum compound in an amount of 6.0% expressed in terms of Al. Various aluminum compounds, such as aluminum chloride, aluminum sulfate, aluminum hydroxide or sodium aluminate, can be used as the aluminum compound used for the aluminum treatment. The above- mentioned compounds may be alone or a mixture of two or more thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing manganese oxide for dry batteries. More specifically, the present invention provides a manganese oxide for dry batteries that is electrochemically highly active, has a small increase in internal resistance during low rate discharge, is economically advantageous, and is particularly useful for manufacturing manganese dry batteries. Relating to a manufacturing method.

(Conventional technology) One of the main materials constituting manganese dioxide-zinc dry batteries (manganese dry batteries, zinc chloride dry batteries, alkaline manganese dry batteries, etc.) is used as a depolarizer (positive electrode active material) to suppress polarization of the positive electrode. Manganese oxide, especially manganese dioxide, is mixed with conductive carbon powder and used in dry batteries in the form of a mixture impregnated with electrolyte.

Taking a manganese dry battery as an example, in addition to the mixture, the main components are a zinc can, carbon rods, and a separator. Among these materials, the one that has the greatest effect on the performance of the dry cell, such as the discharge life, is , the properties of manganese dioxide. Therefore,
The selection of manganese dioxide is very important in the design of dry cell batteries.

Manganese dioxide includes natural manganese dioxide, electrolytic manganese dioxide, and chemically synthesized manganese dioxide. Traditionally, natural manganese dioxide ore has been used in large quantities as a material for dry cell batteries because it is cheap, but in recent years it has become difficult to obtain natural manganese dioxide ore with good electrochemical properties, so electrolytic manganese dioxide ore has been used as a material for dry batteries. has gradually come to be used.

Electrolytic manganese dioxide is usually produced by anodizing an aqueous solution of manganese sulfate, and the crystal phase is mainly 1-
It is composed of Mn0□ and is generally considered to be optimal as a depolarizing agent. However, since electrolytic manganese dioxide requires a large amount of electricity for the electrolytic process, it has the drawback of inevitably being expensive in Japan, where electricity costs are high.

Therefore, high-quality manganese dry batteries use only electrolytic manganese dioxide, while lower-grade manganese batteries use a mixture of electrolytic manganese dioxide and natural manganese dioxide in a specific ratio. ing. The aim of low-grade products is of course to lower the price of dry cell batteries, but it is also necessary that the performance exceeds a certain standard value. The standard value varies depending on the level of discharge resistance to be tested, but for example, in a 40Ω continuous discharge test of a single type, the time during which a final voltage of 0.9 V can be maintained (hereinafter abbreviated as continuous discharge time) is at least 200 time, 2Ω
A continuous discharge time of 330 minutes or more with low resistance (high rate) discharge is required.

In order to meet such standard values, electrolytic manganese dioxide is mixed even in low-grade products, but in order to reduce the cost of dry batteries, it is necessary to at least meet the performance standards of low-grade manganese dioxide without mixing electrolytic manganese dioxide. It has been desired to develop low-cost manganese dioxide that has electrochemical properties that meet the requirements.

Against this technical and economical background, there has recently been a trend to develop low-cost and inexpensive manufacturing methods for manganese dioxide by activating natural manganese dioxide through chemical treatment or chemical synthesis. It's here.

For example, Japanese Patent Application Laid-Open No. 60-221324 discloses that manganese ore or manganese compounds are roasted at a temperature of 400°C or higher, and then manganese dioxide obtained by acid treatment is used as a raw material.
A method for manufacturing manganese dioxide is disclosed, which comprises compression molding this manganese dioxide powder using a roll press under a pressure of 1 to 10 tons/ell, and then pulverizing it to a desired particle size. Hereinafter, manganese dioxide obtained by such chemical synthesis will be abbreviated as chemical manganese dioxide. Chemical manganese dioxide does not require electricity, so
It is considerably cheaper than electrolytic manganese dioxide.

As is well known, dry batteries are used in a variety of ways in a variety of fields, so they must satisfy many performance evaluation standards in addition to those listed above. Among these, a particular problem in practical use is applications in which high external resistance (low rate) discharge and low external resistance (high rate) discharge are repeated alternately, for example, when manganese dry batteries are used as a power source for portable radio equipment. In this case, the internal resistance of the dry battery mixture increases during low rate discharge. Taking radio equipment as an example, in order to constantly receive signals from the outside, it is necessary to constantly flow a minute current equivalent to an external resistance connection of about 300 to 600 ohms through the circuit, resulting in a long-term low rate discharge (minute current). As a result, the internal resistance of the mixture increases by 5 to 10 times its initial value. On the other hand, when a radio device sounds a warning signal to notify that it has intercepted a power reception signal from a communication partner, it is necessary to supply a large current corresponding to a low external resistance (high rate) discharge to the circuit. However, if the internal resistance of a dry battery increases due to long-term low-rate discharge, that internal resistance will be added during high-rate discharge, making it impossible to extract the desired current and causing a problem in which the signal cannot be emitted.

Such obstacles in specific applications are also a major problem when dry batteries are constructed using chemical manganese dioxide. The cause and mechanism of increase in internal resistance during low-rate discharge are not clearly elucidated, but in the case of chemical manganese dioxide, M
Because the nO□ fine powder is crushed after pressure molding press, it has high electrolyte absorption properties, and the lack of liquid at the particle interface involved in battery reactions and the accumulation of reaction product layers inside the particles are prevented. It is presumed that this contributes to the increase in resistance.

(Problems to be Solved by the Invention) Therefore, manganese dioxide used as a depolarizer for dry batteries is inexpensive, and at the same time, from the viewpoint of battery performance.
It is particularly important to provide materials that do not increase the internal resistance of dry cells during long-term, low-rate discharge.

An object of the present invention is to use manganese dioxide which is significantly cheaper than electrolytic manganese dioxide, has high activity, has extremely low increase in internal resistance especially during high external resistance (low rate) discharge, and which is capable of producing at least a low grade manganese dioxide. An object of the present invention is to provide a method for producing manganese oxide for dry batteries that satisfies the performance standards required for.

(Means for Solving the Problems) As a result of continuing various studies to solve the above problems, the present inventors found that if aluminum treatment is applied under specific pH conditions during the manufacturing process of chemical manganese dioxide, The present invention was completed based on the knowledge that the increase in internal resistance during low rate discharge can be effectively suppressed and the above object can be achieved.

Here, the gist of the present invention is to roast a manganese compound at a temperature higher than its decomposition temperature to produce manganese oxide mainly composed of Mn2O3 and/or Mn3O4, and then to process this product with a mineral acid. After processing to obtain manganese oxide mainly composed of MnO2, this is treated in an aqueous medium containing an aluminum compound with a pH of 2.0 to 4.0 or 10 or more to obtain 75% or more Mn01 and AQ. The present invention provides a method for producing a manganese oxide for dry batteries, characterized by obtaining a manganese oxide containing 6.0% or less of an aluminum compound.

The aluminum treatment of manganese dioxide is described in Japanese Patent Application Laid-open No. 5
Although disclosed in No. 9-175563, the object to be treated is limited to expensive and highly purified electrolytic manganese dioxide, and is not intended for cheap chemically converted manganese dioxide that does not have high purity manganese dioxide as in the present invention. .

(Function) The present invention will be explained in detail below. In addition, in this specification, % is weight % unless otherwise specified.

Manganese oxide produced by the method of the present invention has a content of 75%
It contains an AQ compound of 6.0% or less as MnO2 and AQ above, and if this condition is satisfied, it satisfies the performance standards required for the above-mentioned low-grade manganese dioxide, and also has a long-term high resistance (low resistance). It was found that the internal resistance of the dry battery does not easily increase even during discharge (rate), and that it has performance suitable for use in dry batteries.

The MnO□ content of the manganese oxide produced by the present invention is
It was found that there is a close relationship with the discharge life of dry batteries. Figure 1 shows that AA type dry cells were manufactured using manganese oxides with various MnO2 contents obtained by the method of the present invention as depolarizers, and the dry cell batteries with a constant resistance of 40Ω reached a utilization rate of 90 to 100%. It is a graph showing the results of examining discharge life (discharge duration) as a relationship with MnO2 content.

As can be seen from this figure, the higher the Mn0z content, the longer the discharge life (however, in order to maintain the discharge duration of 200 hours, which is the performance standard for low-grade products, Mn of 75% or more is required.
0t content is required. It is clear from Fig. 1 that it is preferable to have as much MnO1 content as possible, but when used for inexpensive low-grade dry batteries, MnO
It is sufficient that □ is about 90% or less. The preferred MnOz content for this purpose is 75-88%.

AQ is effective in suppressing an increase in internal resistance during discharge at high resistance (low rate) as described above. Figure 2 shows that the AQ content in manganese oxide is high resistance (low rate) of 150Ω.
2 is a graph showing the influence on internal resistance (·) in discharge and discharge duration (0) in low resistance (high rate) discharge of 2Ω (MnO2 content of manganese oxide 80%). Second
The internal resistance in the figure is expressed as the internal resistance when the voltage drops to 0.90V during continuous discharge of 150Ω, as shown in FIG. As shown in FIG. 3, the internal resistance increases as the discharge progresses.

As can be seen from Fig. 2, the effect of suppressing the increase in internal resistance during long-term low rate discharge, which is the main objective of the present invention, becomes noticeable when only a very small amount of about 0.01% of A (i) is contained. .

Therefore, there is no particular lower limit to the AQ content.

When the AQ content is about 0.3 to 6%, the above effects due to AQ become particularly remarkable. When the M content exceeds 6.0%, the increase in internal resistance is no different from that without the addition of F, and the low resistance continuous discharge duration at 2 ohms falls below 330 minutes, which is the performance standard for low-grade products. Therefore, the AQ content in the product of the method of the present invention is limited to 6.0% or less. The preferred AQ content is 0.3-6.0%.

The reason why the above effect is achieved by the presence of AQ is not clear, but it can be considered as follows. AQ 3”
When ions are adsorbed on the surface of manganese dioxide particles, they are surrounded by negatively charged 01l- ions. Due to its solid nature, OH- ions are light and can move around freely, and in order to maintain electrical neutrality, there are a large number of ions around them. Together with (e-), it participates in the electromotive reaction of the battery, resulting in 0■- ions and H° ions,
That is, since water molecules exist in a dissociated state around the manganese dioxide particles, diffusion of zinc ions is promoted and local accumulation of basic zinc hydroxide, which is a reaction product, is also prevented. As is well known, inhibition of zinc ion dispersion is one of the causes of increased internal resistance. Since he9 is a trivalent ion, it can coordinate a large amount of OH- ions, and it does not inhibit battery reactions, so it is inferred that it is particularly suitable for preventing the above-mentioned increase in internal resistance. .

The remainder of the manganese oxide of the present invention other than MnO□ and the sulfur compound is substantially other manganese oxide (Mn20
s and Mr+aOa, etc.). However, it may contain a trace amount of impurities that are inevitably mixed into the raw materials or during the manufacturing process. Further, it may contain some moisture.

In addition to manganese compounds such as manganese sulfate, manganese carbonate, and manganese nitrate, the manganese compounds used as raw materials in the method of the present invention include manganese carbonate (rhomganite), manganese dioxide (soft manganese ore), and Mn2O3.
Or Mn. Any manganese-containing material, such as various manganese ores such as manganese ore whose main component is Ol, and wastes whose main component is a manganese compound (e.g., manganese salt produced as a by-product in the acid treatment step of the process of the present invention) That's fine.

These may be used alone or in combination of two or more. The particle size of the manganese compound used as a raw material is preferably about 5 particles or less, and if necessary, it may be appropriately pulverized before use.

According to the method of the present invention, the above-mentioned manganese compound is first roasted and thermally decomposed to produce Mr203 and/or Mr+.
Manganese oxide containing +Os as a main component is obtained.

This roasting is carried out by heating the starting materials used above their decomposition temperature in a suitable roasting atmosphere. The decomposition temperature is, for example, 500 to 950°C for soft manganese ore.
, MnC0, and its ore about 400-550°C
, Mn5O=, it is about 900 to 1050''C.

The roasting atmosphere is selected appropriately depending on the raw materials used.
Usually, an oxygen-containing atmosphere such as air may be used.

However, in the case of soft manganese ore, it is preferable to use a reducing roasting atmosphere, for example, an autogenous atmosphere in which the inflow of air is blocked.

The composition of manganese oxide obtained by roasting varies depending on the roasting temperature. For example, at a roasting temperature of about 700 to 950°C, MnzO3 is mainly produced, and as the temperature rises, Mn30. The generation ratio of will increase. Furthermore, the production ratio of these two types of manganese oxides can also be controlled by adjusting the amount of oxygen supplied during roasting. That is, by increasing the air supply amount and pressure during roasting, it is possible to selectively generate Mn2O3 even under high temperature conditions.

As described above, the roasting conditions are not particularly limited and may be appropriately selected depending on the raw materials used and the desired composition of manganese oxide. The roasting time will vary depending on the temperature and other processing conditions, as well as the type and particle size of the raw manganese compound, but will generally be within 2 hours. There is no particular limit to the ratio of Mn2O3 to Mn30g in the manganese oxide produced by roasting, but in order to reduce the amount of soluble manganese salt produced as a by-product in the next acid treatment step, the production ratio of Mn20:+ should be increased. is preferable, and it is particularly preferable that substantially the entire amount is Mr+403.

In order to obtain a manganese oxide suitable for use in dry batteries by the method of the present invention, it is preferable that the mineral acid treatment performed after roasting reach the deep part of the particles. In that sense, the smaller the particle size of the particles subjected to mineral acid treatment, the better, and the maximum particle size of the particles should be reduced to 70%.
It was found that it is desirable to adjust the granularity to below the voice level.

For example, if the manganese raw material is finely pulverized before roasting, this particle size adjustment can be carried out by classifying the manganese oxide after roasting.
It is only necessary to remove particles below 0/JTII. If the raw material manganese compound has a relatively large particle size, it may be roasted, pulverized, and then classified as described above.

After roasting, the manganese oxide whose particle size has been adjusted as desired is then treated with an acid to obtain highly active manganese oxide mainly consisting of γ-MnO2. By acid treatment, lower oxide Mn2
0. , and Mn3O4 are tetravalent manganese (insoluble Mn
O□) and divalent manganese (a soluble salt of Mn'' and an acid anion) are disproportioned, so if the insoluble matter is recovered by solid-liquid separation after acid treatment, the oxidation mainly consists of highly active T-MnO□. Manganese is obtained. A large amount of by-product divalent manganese salt is dissolved in the separated solution, so this manganese salt is recovered by crystallization and used as part of the raw material of the present invention in the roasting process. It is advantageous to use it in

This acid treatment is carried out using one or more mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid under conditions that mainly produce 7-MnO. 7 by acid treatment of lower manganese oxide
- Regarding the chemical synthesis of Mn02, many methods have been proposed in the past, and acid treatment may be carried out according to these known methods, and the treatment conditions such as temperature and acid concentration may be the same as conventional methods ( For example, Japanese Patent Application Laid-Open No. 53-82697,
Publication No. 60-255626, No. 61-14137,
(See Publication No. 62-87418, etc.).

The acid treatment is carried out until manganese oxide with an MnO7 content of 75% or more is obtained.

After acid treatment, the manganese oxide recovered by solid-liquid separation means such as filtration is washed with water to remove the acid and soluble M
n'' ions are removed.

Conventionally, acid treatment was the last chemical treatment, so neutralization was performed to remove the acid on the particle surface after acid treatment, but in the present invention, aluminum treatment is further performed, so neutralization after acid treatment is Not necessarily necessary.

For aluminum treatment, aluminum chloride, aluminum sulfate, aluminum hydroxide, sodium aluminate,
Various aluminum compounds can be used, such as polyaluminum chloride and highly basic aluminum chloride.

These may be used alone or in a mixture of two or more.

The aluminum treatment method is not particularly limited as long as it is a method that can uniformly adsorb an aluminum compound onto the surface of the manganese oxide particles.

For example, this can be carried out by dispersing manganese oxide particles obtained by acid treatment in water, adding an appropriate amount of an aluminum compound thereto, and stirring appropriately to adhere an alkali to the particle surface.

The pH of the aqueous medium of the treatment solution during aluminum treatment is 2.
0 to 4.0 or 10 or more. When the pH exceeds 4.0 and reaches 10, precipitation of aluminum hydroxide occurs, and 8Q does not enter the pores inside the manganese oxide particles, making it impossible to obtain the effects of the present invention. If the pH is less than 2.0, a large amount of alkali will be consumed in the neutralization step after the acid treatment, which is not economical.

As mentioned above, A in the finally obtained manganese oxide
Since the 12 content is 6.0% or less, the amount of the aluminum compound to be used can be determined by experiment so that a manganese oxide with a desired 12 content can be obtained within this range. Although the treatment conditions are not particularly limited, the treatment is usually performed at room temperature for several minutes to several hours. Thereafter, the manganese oxide is recovered by appropriate means such as filtration, neutralized if necessary, and then washed with water.

The bulk density (or tap density) or particle size of the aluminum-treated manganese oxide may be adjusted according to conventional methods, if necessary. The increase in bulk density is
This is achieved by crushing after compression molding.

The timing of the aluminum treatment is not particularly limited as long as it is after the acid treatment; for example, after the acid treatment, the manganese oxide that has been filtered and washed with water is dried, compression molded and pulverized first,
A subsequent aluminization treatment may be performed, and this modification does not make a significant difference in the cell performance of the product.

(Example) Next, the present invention will be specifically explained with reference to Examples.

However, the examples are for illustrative purposes and are not intended to limit the scope of the invention.

In the examples, "tap density" refers to manganese dioxide whose particle size has been adjusted to -200 mesh, whose inner diameter is 28 mm, and whose volume is 10 mm.
This is the density (weight/volume after tapping) calculated from the weight (g) after being placed in a 0 cc cylinder and dropped 300 times from the height of 2ONI11.

1 vessel 1 Raw material 186 made by pulverizing soft manganese ore whose main component is electrochemically inactive β-Mn02 to a maximum particle size of 5 or less
kg is roasted in an autogenous atmosphere at about 850-900°C to produce manganese oxide 16 consisting essentially of Mn201.
I got 7 kg. The reaction during this time is expressed by the following formula.

2 Mn0z(β) →Mn2O3+ 'A Ot''
・■ The obtained MnzOl is crushed and classified to form a powder with a maximum particle size of 10 pn or less, and then mixed with sulfuric acid (10N) 20I! , was used to perform acid treatment at a temperature of 90°C for 60 minutes. In this acid treatment, the reaction shown by the following formula occurs.

MnzO+ + H2SO4→Mn0g + MnSO
4+ H2O・, -■ After acid treatment, after filtering out the solid content,
This was washed with water and filtered to obtain 100 kg of manganese oxide containing y-Mn02 as a main component. This manganese oxide contained 80.4% MnO, and substantially all of the MnO2 was electrochemically active T-Mno□.

10 kg (dry equivalent) of the manganese oxide powder thus obtained was dispersed in an amount of water such that the solid/liquid ratio was 0.18,
Then, while adjusting the pH to 3.5 with 5%-NaOH,
．． 442 ml of an aqueous polyaluminum chloride solution containing 56% AQ was added over 10 minutes, and the resulting slurry was stirred at room temperature for 1 hour to perform aluminum treatment.

Next, in order to adjust the pH of the manganese oxide to be suitable for dry cells, 5%
Neutralization was performed by adding NaOH to the slurry and stirring at room temperature for about 1 hour while maintaining the pH. Then,
After filtering the slurry and washing and drying the solid content, 2
0 ton/cm” (roll linear pressure 2.Oton/m+
), the tap density is 1.80 g/cd.
An M-containing manganese oxide was obtained.

The composition of this product, together with the composition of the manganese oxide before aluminization, is shown in Table 1 below.

The HeQ content without aluminum treatment shown in Table 1 is:
This shows inert A(I oxides (AlzOs, etc.), which are gangue components contained in the raw material ore, and this does not contribute in any way to suppressing the increase in internal resistance as explained in FIG. 4 as an effect of the present invention. However, because it is difficult to distinguish between the adsorbed AQ content derived from aluminum treatment and the AQ content derived from gangue in chemical analysis, the AQ content in the manganese oxide, which is the product of the present invention, is The amount shall be the total AQ content obtained as an analytical value.However, even if AQ derived from gangue is included, aluminum treatment is an essential step in the method of the present invention, and treatment is not required after aluminum treatment. The M content must be increased compared to before.

Using the AQ-containing chemical manganese oxide obtained in this example, 300 AA type manganese dry batteries were prototyped in accordance with the dry battery trial production test method stipulated in JIS K-1467.

For each prototype dry battery, temperature 20±2°C1 resistance 1
A discharge test was conducted by continuous discharge under the condition of 50Ω, and the discharge duration (days) until the discharge end voltage (0.9V) and the change in internal resistance during discharge were measured. Measuring internal resistance is
The measurement was performed using a four-probe impedance analyzer at 1 kHz AC. The results are shown in the attached Figure 4.

For comparison, chemically formed manganese oxide prepared in exactly the same manner as above except that no aluminum treatment was performed.
FIG. 4 also shows the results of a discharge test using a AA type dry battery, which was similarly produced using the composition shown in Table 1 as "without aluminum treatment".

From FIG. 4, it can be seen that when the manganese oxide treated with aluminum according to the present invention is used, the increase in internal resistance is significantly suppressed and the discharge life becomes longer than when no aluminum treatment is used.

1 vessel 1 In neutralization and pH adjustment after aluminum treatment, 5
He Q-containing manganese oxide 1 was prepared in the same manner as in Example 1 except that 5% NHOH was used instead of %NaOH.
0 kg (dry equivalent) was obtained.

Using this manganese oxide, a monomer was prepared in the same manner as in Example 1.
Three hundred type dry batteries were manufactured, and the discharge duration and change in internal resistance of each battery in a 150Ω continuous discharge test were measured in the same manner as in Example 1. The obtained results showed the same tendency as the results of Example 1 shown in FIG. 4, and it was demonstrated that the aluminum treatment significantly suppressed the increase in internal resistance and improved the discharge life.

1Mn0z obtained by performing acid treatment in the same manner as in Example 1
10 kg (dry equivalent) of manganese oxide powder mainly composed of
was dispersed in an amount of water to give a solid/liquid ratio of 0.18, and then the pH of the aqueous medium was brought to 12.0 with 10% NaOH.

Anhydrous aluminum chloride 14
A 20% aqueous solution of 81 g in water was added over 15 minutes and stirred at room temperature for about 1 hour while maintaining the slurry p)I at 12.0. Next, the slurry pH was adjusted to 7 with 1N sulfuric acid.
．． The solution was neutralized to 0 and stirred for an additional 1 hour while maintaining the pH at 7.0 for 1 hour.

Thereafter, the slurry was filtered, the solid content was washed with water and dried, and the same method as in Example 1 was carried out to compress, crush and classify the slurry to produce chemically converted manganese oxide 1 with a tap density of 1.80 g/c111.
0 kg (dry equivalent) was obtained. Its composition is shown in Table 2 below, along with the composition of manganese oxide before aluminum treatment.

Using this Q-containing manganese oxide, 300 AA-type dry batteries were prototyped in the same manner as in Example 1.
The discharge duration and internal resistance change in the 50Ω continuous discharge test were measured in the same manner as in Example 1. The obtained results showed the same tendency as the results in Example 1 shown in FIG. 4, and it was found that the aluminum treatment significantly suppressed the increase in internal resistance and improved the discharge life.

(Effect of the invention) According to the method for producing manganese oxide for dry batteries of the present invention,
During the manufacturing process of chemical manganese dioxide, aluminum treatment is performed under specific pH conditions, and the M of the product is
By maintaining the n0z content and heq content within a specific range, manganese oxide effectively suppresses the increase in internal resistance during high resistance (low rate) discharge, which has been a problem in the past.
It becomes possible to manufacture at low cost.

In particular, the method for manufacturing manganese for dry batteries of the present invention does not use energy-consuming processes such as electrolysis, and involves simple chemical roasting, acid treatment, aluminum treatment, and simple processing as necessary. Since it is carried out by pressure compression and pulverization, it is very cost-effective compared to the electrolytic method, and can be produced at the same cost as the low-grade manganese dioxide currently in use. Furthermore, its electrochemical performance can meet at least the performance standards of lower-grade manganese dioxide without adding expensive electrolytic manganese dioxide.

Therefore, by incorporating the manganese oxide produced by the method of the present invention into a dry battery as a depolarizing agent, a dry battery having excellent performance can be economically produced, and the present invention is particularly useful for producing inexpensive manganese dry batteries. The method is very advantageous.

[Brief explanation of the drawing]

Figure 1 is a graph showing the relationship between the MnO□ content of manganese oxide and the 40Ω continuous discharge duration of a battery constructed from it.
A graph showing the variation in internal resistance (・) and 2Ω continuous discharge duration (0) of a dry battery at 0 and 9 V cutoff in 0Ω continuous discharge.
A graph showing changes in potential (・) and internal resistance (○) depending on the duration of 50Ω continuous discharge (days), and FIG. 2 is a graph showing changes in potential and internal resistance, where the broken line shows the case of the M-containing manganese oxide according to the present invention, and the solid line shows the case of the manganese oxide not subjected to the conventional aluminum treatment.

Claims (1)

[Claims] (1) Roasting a manganese compound at a temperature above its decomposition temperature to produce manganese oxide containing Mn_2O_3 and/or Mn_3O_4 as the main component, and then treating this product with mineral acid to produce manganese oxide containing MnO_2 as the main component. After obtaining manganese oxide, it is converted to pH containing aluminum compound.
2.0 to 4.0 or 10 or more to obtain a manganese oxide containing 75% or more MnO_2 and 6.0% or less aluminum compound as Al, A method for producing manganese oxide for dry batteries.