JP2014019634A - Production method of trimanganese tetraoxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method that can obtain trimanganese tetraoxide by higher producibility than that of a conventional production method.SOLUTION: A production method of trimanganese tetraoxide in which the production of trimanganese tetraoxide is performed by crystallization from a manganese salt aqueous solution not through manganese hydroxide, includes a process in which the production of trimanganese tetraoxide is performed by crystallization in which a slurry density of a slurry containing trimanganese tetraoxide after crystallization reaction exceeds 1.13 g/cm.

Description

  The present invention relates to a method for producing a method for producing trimanganese tetraoxide. Specifically, the present invention relates to a method for producing trimanganese tetroxide that can obtain trimanganese tetroxide in a high yield.

  Since manganese tetraoxide has a high theoretical density among manganese oxides, it has been attracting attention as a manganese raw material from which a lithium-manganese composite oxide having a high filling property can be obtained.

  For example, manganese trioxide obtained by obtaining manganese hydroxide from a manganese complex salt obtained by reacting manganese ions with a complexing agent in an aqueous solution and oxidizing the manganese hydroxide is reported. (Patent Document 1).

  Further, trimanganese tetraoxide having a tap density of 1.6 g / mL or more obtained by crystallization from an aqueous manganese salt solution without passing through a manganese hydroxide has been reported (Patent Document 2).

JP 2001-114521 A WO2012 / 046735A1

  In the production method described in Patent Document 1, a complexing agent and manganese ions are aged to obtain manganese hydroxide, which is then oxidized to obtain trimanganese tetraoxide. In the method for producing manganese trioxide that oxidizes manganese hydroxide, if manganese hydroxide is not sufficiently oxidized, not only the yield of manganese trioxide is lowered, but this manganese hydroxide becomes an impurity. In addition, this manufacturing method requires a long time for aging manganese hydroxide, and furthermore, it stops the reaction by switching the atmosphere between the aging step and the oxidation step, and takes time for uniformly oxidizing manganese hydroxide. Manufacturing efficiency was low because it was necessary.

  The production method described in Patent Document 2 can obtain manganese trioxide directly from an aqueous solution, and does not require aging time of manganese hydroxide or switching of the atmosphere from the aging step to the oxidation step. Therefore, compared with the manufacturing method which oxidizes manganese hydroxide, trimanganese tetroxide can be obtained with a high yield and high manufacturing efficiency.

  However, there is a demand for a production method capable of obtaining trimanganese tetraoxide with higher production efficiency than these conventional production methods.

  In order to improve the production efficiency of the method for producing trimanganese tetroxide, the present inventors have made extensive studies on improving the yield. As a result, in the method for producing trimanganese tetraoxide from the manganese salt aqueous solution without passing through the manganese hydroxide, a part of the manganese ion in the manganese salt aqueous solution is not crystallized. It was found that the yield decreased because it remained in the aqueous solution, and that the yield of trimanganese tetroxide increased only when the amount of manganese salt aqueous solution used was increased, and the yield was not improved. It was. Furthermore, the present inventors have found that the slurry density of the slurry containing trimanganese tetraoxide after the crystallization reaction is related to the yield of trimanganese tetraoxide, and have completed the present invention.

That is, the present invention is a method for producing manganese trioxide by crystallizing manganese trioxide from an aqueous manganese salt solution without passing through manganese hydroxide, and a slurry containing trimanganese tetraoxide after the crystallization reaction A process for crystallizing trimanganese tetraoxide with a slurry density exceeding 1.13 g / cm ³ .

  Hereinafter, the method for producing trimanganese tetraoxide of the present invention will be described.

  In the method for producing trimanganese tetraoxide of the present invention, trimanganese tetraoxide is crystallized from an aqueous manganese salt solution without going through manganese hydroxide. Thereby, trimanganese tetraoxide can be manufactured.

  Manganese oxide can be produced without precipitation of manganese hydroxide crystals in the alkaline region from the manganese salt aqueous solution by crystallizing manganese trioxide from the manganese salt aqueous solution without going through the manganese hydroxide. it can. That is, the method for producing trimanganese tetraoxide of the present invention does not have a step of depositing manganese hydroxide crystals in an alkaline region from an aqueous manganese salt solution and oxidizing the manganese hydroxide with an oxidizing agent. Thus, the manufacturing method of the present invention can manufacture trimanganese tetraoxide without going through such steps.

  In the method for producing trimanganese tetraoxide of the present invention, the crystal phase of manganese hydroxide is not formed at all, and after the microcrystal of manganese hydroxide is precipitated for a short time, it is a hexagonal plate-like crystal. And adding to trimanganese tetroxide before growing. That is, the method for producing trimanganese tetraoxide of the present invention is characterized in that hexagonal plate-like manganese hydroxide crystals do not occur. Whether or not a hexagonal plate-like manganese hydroxide crystal has occurred can be determined by observing the particle shape of the resulting manganese trioxide.

  In the method for producing manganese oxide of the present invention, the pH of the aqueous manganese salt solution is adjusted to a pH at which manganese hydroxide is difficult to be generated. As a result, manganese ions in the aqueous solution can be directly oxidized to crystallize trimanganese tetraoxide.

  In the production method of the present invention, the pH of the aqueous manganese salt solution is preferably a pH at which manganese hydroxide is not easily generated, and more preferably a pH from weakly acidic to weakly alkaline. The pH of such an aqueous manganese salt solution is preferably pH 6 or more and pH 9 or less, more preferably pH 6.5 or more and pH 8 or less. By making the pH of the manganese salt aqueous solution within this range, it becomes more difficult to produce manganese hydroxide.

  The pH of the aqueous manganese salt solution is within these ranges, and it is more preferable to maintain the pH constant. Maintaining the pH constant means maintaining the pH in the range of ± 0.5, preferably maintaining the pH in the range of ± 0.3, and more preferably maintaining the pH in the range of ± 0.1. Is to keep in range.

  When adjusting pH of manganese salt aqueous solution, it is preferable to use alkaline aqueous solution (henceforth, aqueous alkali solution). Although there is no restriction | limiting in the kind of alkaline aqueous solution, Aqueous solutions, such as sodium hydroxide and potassium hydroxide, can be illustrated.

  Examples of the concentration of the alkaline aqueous solution include 1 mol / L or more.

In the production method of the present invention, the redox potential of the aqueous manganese salt solution with respect to the standard hydrogen electrode (hereinafter simply referred to as “redox potential”) is preferably 0 mV or more and 300 mV or less, and is 30 mV or more and 150 mV or less. Is more preferable. When the oxidation-reduction potential of the manganese salt aqueous solution is within this range, it becomes difficult to produce manganese hydroxide. In particular, when the oxidation-reduction potential of the manganese salt aqueous solution is 300 mV or less, γ-MnOOH having a needle-like particle form (true density: 4.3 g / cm ³ ) is hardly generated as a by-product, and the resulting tetra-oxide Manganese fillability tends to be high.

  The oxidation-reduction potential of the manganese salt aqueous solution is within these ranges, and it is more preferable to keep it constant. To keep the redox potential constant is to maintain the redox potential in a range of ± 50 mV, preferably to maintain the redox potential in a range of ± 30 mV, and more preferably, the redox potential is ±±. It is to maintain in the range of 20 mV.

  In this way, crystallization is performed with the pH, oxidation-reduction potential, or both within the above range, and further, the pH, oxidation-reduction potential, or both are within the above-mentioned range, and these are maintained constant. By crystallizing, the filling property of the obtained trimanganese tetraoxide particles becomes high, and the reactivity with the lithium compound becomes uniform.

  Examples of the aqueous manganese salt solution used in the production method of the present invention include aqueous solutions of manganese sulfate, manganese chloride, manganese nitrate, and manganese acetate. Moreover, what melt | dissolved metal manganese, manganese oxide, etc. in various acid aqueous solutions, such as a sulfuric acid, hydrochloric acid, nitric acid, and an acetic acid, can also be used.

  The concentration of the aqueous manganese salt solution is not limited, but is preferably 1 mol / L or more. By setting the concentration of the aqueous manganese salt solution to 1 mol / L or more, trimanganese tetraoxide can be obtained efficiently.

  In the production method of the present invention, it is preferable to crystallize the manganese salt aqueous solution at a temperature of 40 ° C. or higher, more preferably 60 ° C. or higher and 95 ° C. or lower, and more preferably 70 ° C. or higher and 90 ° C. or lower. preferable. By setting the temperature of the manganese salt aqueous solution at the time of crystallization within this range, crystallization of trimanganese tetroxide is promoted, and the particle size of trimanganese tetroxide tends to be uniform.

  In the production method of the present invention, it is preferable to perform crystallization using an oxidizing agent. Although the kind of oxidizing agent is not specifically limited, oxygen-containing gas (including air), hydrogen peroxide, and the like can be exemplified. It is preferable to use an oxygen-containing gas as the oxidizing agent, and it is more preferable to crystallize by blowing it into an aqueous manganese salt solution. Thereby, crystallization of trimanganese tetraoxide is likely to occur uniformly.

  In the production method of the present invention, it is preferable to mix a manganese salt aqueous solution and an alkaline aqueous solution. Thereby, direct crystallization of trimanganese tetraoxide from a manganese salt aqueous solution can be performed continuously. In the production method of directly crystallizing trimanganese tetraoxide from the manganese salt aqueous solution of the present invention, there is no need to change the reaction atmosphere. Therefore, in the production method of the present invention, trimanganese tetraoxide can be produced continuously by mixing an aqueous manganese salt solution and an aqueous alkaline solution.

  The mixing method of the manganese salt aqueous solution and the alkaline aqueous solution is not particularly limited as long as both can be uniformly mixed. Examples of the mixing method include a method in which an alkaline aqueous solution is added to a manganese salt aqueous solution and mixed, a method in which a manganese salt aqueous solution and an alkaline aqueous solution are added to a solvent such as pure water, and the like. In order to sufficiently and uniformly react the manganese salt aqueous solution and the alkaline aqueous solution, the mixing method is preferably a method in which the manganese salt aqueous solution and the alkaline aqueous solution are added to a solvent such as pure water and mixed. In such a mixing method, the rate at which manganese tetroxide crystallizes can be easily controlled by controlling the rate at which the manganese salt aqueous solution and the alkaline aqueous solution are added. Note that the slower the crystallization rate, the larger the particle size of the trimanganese tetraoxide produced, and the higher the tap density.

In the manufacturing method of this invention, the slurry density of the slurry containing trimanganese tetraoxide after crystallization reaction exceeds 1.13 g / cm < ³ >, and the process of crystallizing trimanganese tetraoxide is included. Thereby, trimanganese tetraoxide can be obtained with a high yield of 85% or more, further 90% or more, or even 95% or more. Therefore, in the production method of the present invention, the slurry density of the slurry containing trimanganese tetraoxide after the crystallization reaction (hereinafter referred to as reaction slurry) exceeds 1.13 g / cm ³ and is 1.135 g / cm ³ or more. it is preferable, more preferably 1.14 g / cm ³ or more, more preferably 1.15 g / cm ³ or more. Furthermore, when the slurry density is 1.2 g / cm ³ or more, trimanganese tetraoxide can be obtained more stably with a yield of 95% or more, for example.

As described above, in the production method of the present invention, manganese trioxide is crystallized in a high yield by crystallizing manganese trioxide from a high slurry density reaction slurry having a slurry density exceeding 1.13 g / cm ^3. Can be obtained.

  The density of the reaction slurry can be adjusted by any method. For example, the density of the reaction slurry can be controlled by appropriately adjusting the manganese concentration of the manganese salt aqueous solution to be used, the alkali concentration of the alkaline aqueous solution, the pH of the reaction slurry, and the oxidation-reduction potential within the above ranges. Among these crystallization conditions, the reaction slurry is obtained by crystallizing trimanganese tetroxide using an aqueous alkali solution having an alkali concentration exceeding 2 mol / L, and further using an aqueous alkali solution having an alkali concentration of 2.5 mol / L or more. The slurry density tends to be within the range of the present invention.

  In the production method of the present invention, the average time for the crystallized manganese trioxide particles to stay in the reaction slurry (hereinafter referred to as average stay time) is preferably 1 hour or more, and preferably 3 hours or more. More preferred. When the average residence time is 1 hour or longer, the particle growth of trimanganese tetroxide proceeds, and the tap density of the resulting trimanganese tetroxide tends to increase. If the average residence time is long, the particle growth of the trimanganese tetroxide particles tends to proceed, but considering the efficiency of particle growth and production efficiency, the average residence time is preferably 30 hours or less, and 20 hours or less. Is more preferable.

  In the production method of the present invention, it is preferable to perform crystallization without coexisting a complexing agent. A complexing agent refers to what has the complexing ability similar to these other than ammonia, ammonium salt, hydrazine, and EDTA.

  These complexing agents affect the crystallization behavior of trimanganese tetraoxide. Therefore, the trimanganese tetroxide obtained in the presence of the complexing agent and the trimanganese tetroxide obtained by the production method of the present invention tend to have different filling properties, particle size distribution, and the like.

  Manganese tetroxide obtained by the production method of the present invention has high filling properties, excellent reactivity with lithium compounds, and has a uniform particle size distribution.

Manganese tetroxide obtained by the production method of the present invention has a high packing density. For example, the tap density may be 1.6 g / cm ³ or more, further 1.8 g / cm ³ or more, and further 2.0 g / cm ³ or more.

Examples of the BET specific surface area of trimanganese tetraoxide obtained by the production method of the present invention include 5 m ² / g or less, further 2 m ² / g or less, and further 1 m ² / g or less.

  The average particle diameter of trimanganese tetraoxide obtained by the production method of the present invention is 1 μm or more and 50 μm or less, further 5 μm or more and 20 μm or less, and further 10 μm or more and 15 μm or less. Furthermore, manganese trioxide obtained by the production method of the present invention has a uniform particle size distribution, and exhibits a so-called monodispersed particle size distribution. Therefore, manganese trioxide obtained by the production method of the present invention has a monomodal particle size distribution with a uniform particle size without going through a particle size adjusting step such as grinding or sieving. Can be provided.

  According to the present invention, it is possible to provide a production method capable of obtaining trimanganese tetraoxide more efficiently than the conventional production method. Furthermore, it is possible to provide a method for producing trimanganese tetroxide, which produces high-filling trimanganese tetraoxide with a higher yield.

  Further, the trimanganese tetraoxide obtained by the production method of the present invention can be used for applications such as a raw material of a lithium manganese composite oxide.

The graph which shows the relationship between the reaction slurry density and the yield of trimanganese tetroxide (●: Example, Δ: Comparative Example). 3 is a particle size distribution of trimanganese tetraoxide obtained in Example 1. FIG.

  Next, although this invention is demonstrated with a specific Example, this invention is not limited to these Examples.

(Measurement of slurry density)
During the crystallization reaction, a part of the reaction slurry in which trimanganese tetraoxide was crystallized was collected with a graduated cylinder, then its volume and weight were measured, and the slurry density was determined by the following equation.

Slurry density (g / cm ³ ) = slurry weight (g) / slurry volume (cm ³ )

(yield)
The reaction slurry after the crystallization reaction was filtered, and the filtrate was recovered. The manganese concentration of the collected filtrate was measured by an ICP method using a commercially available inductively coupled plasma optical emission spectrometry (hereinafter, ICP) apparatus. The manganese content in the filtrate was determined from the obtained manganese concentration and the collected filtrate amount. From the manganese content and the total amount of manganese in the manganese sulfate aqueous solution used for crystallization, the yield was determined by the following formula.

yield(%)
= {(Total manganese content of manganese sulfate aqueous solution)-(manganese content in filtrate)} / (total manganese content of manganese sulfate aqueous solution) × 100

(Tap density)
The density after 2 g of sample was filled in a 10 mL graduated cylinder and tapped 200 times was defined as the tap density.

(Average particle size)
As the average particle size of the sample, the particle size of the particles having the highest volume fraction (hereinafter, “moderate particle size”) was measured. A commercially available particle size measuring device (trade name: MICROTRAC HRA 9320-X100, manufactured by Nikkiso Co., Ltd.) was used for the measurement of the mode particle size. Before the measurement, the sample was dispersed in pure water to obtain a measurement solution, and ammonia water was added to adjust the pH to 8.5. Thereafter, the measurement solution was subjected to ultrasonic dispersion for 3 minutes, then the mode particle size was measured, and the obtained value was taken as the average particle size.

(X-ray diffraction measurement)
The crystal phase of the sample was measured by X-ray diffraction. The measurement was performed with a general X-ray diffractometer. A CuKα ray (λ = 1.5405 mm) is used as the radiation source, the measurement mode is step scan, the scan condition is 0.04 ° per second, the measurement time is 3 seconds, and the measurement range is 2 ° to 5 ° to 80 °. Measured with

(BET specific surface area)
The BET specific surface area of the sample was measured by nitrogen adsorption by the BET single point method. In addition, the sample used for the measurement of the BET specific surface area was deaerated by heating at 150 ° C. for 40 minutes prior to the measurement of the BET specific surface area.

(Chemical composition analysis)
After dissolving the sample with a mixed aqueous solution of hydrochloric acid and hydrogen peroxide, the amount of manganese was measured by ICP method.

Example 1
The pure water was brought to 80 ° C. and stirred while blowing air so that the oxidation-reduction potential was 30 mV. A manganese oxide was crystallized by continuously adding a 2 mol / L aqueous manganese sulfate solution to obtain a reaction slurry. When adding the manganese sulfate aqueous solution, a 2.7 mol / L sodium hydroxide aqueous solution was appropriately added to the reaction slurry so that the reaction slurry had a pH of 7. The slurry density of the reaction slurry thus obtained was 1.137 g / cm ³ . A manganese sulfate aqueous solution and a sodium hydroxide aqueous solution were added to the reaction slurry, and at the same time, crystallization was performed for 8 hours while extracting the same amount of the reaction slurry. Thus, crystallization was performed with the average residence time of the manganese oxide in the slurry being 8 hours while maintaining the slurry density. Thereafter, the reaction slurry was filtered, washed and dried to obtain a manganese oxide. The yield of the manganese oxide thus obtained was 86.2%. The experimental conditions and results are shown in Table 1.

The obtained manganese oxide had a tap density of 1.83 g / cm ³ and a BET specific surface area of 0.5 m ² / g. The particle size distribution was monodispersed and the average particle size was 11.0 μm. In addition, the crystal phase is the JCPDS pattern No. It was a pattern equivalent to the X-ray diffraction pattern of 24734 and had a spinel structure. Moreover, when the oxidation degree of manganese of the manganese oxide was expressed by MnOx, x = 1.34. From these results, it was confirmed that the obtained manganese oxide was a single phase of trimanganese tetraoxide. In addition, about the obtained manganese trioxide, the density (henceforth "JIS density") by the measuring method according to JISR1628 was measured. As a result, the JIS density of trimanganese tetraoxide of Example 1 was 2.01 g / cm ³ , which was 1.1 times the tap density. The particle size distribution of the obtained trimanganese tetraoxide is shown in FIG.

Example 2
Stirring while blowing air so that the oxidation-reduction potential of pure water is 104 mV, adding 2.6 mol / L aqueous sodium hydroxide solution to the reaction slurry so that the pH of the reaction slurry is 6.8, And trimanganese tetroxide was obtained by the same method as Example 1 except having performed crystallization by making the average residence time of manganese oxide in a slurry into 18 hours. The slurry density of the obtained reaction slurry was 1.140 g / cm ³ .

  The yield of the manganese oxide thus obtained was 94.6%. The experimental conditions and results are shown in Table 1.

The obtained manganese oxide had a tap density of 1.61 g / cm ³ and a BET specific surface area of 1.5 m ² / g. Moreover, the particle size distribution was monodisperse, the average particle size was 9.3 μm, and the crystal phase was trimanganese tetraoxide composed of a single phase of trimanganese tetraoxide.

Example 3
Other than stirring while blowing air so that the redox potential of pure water becomes 70 mV, and adding 16.1 mol / L sodium hydroxide aqueous solution to the reaction slurry so that the pH of the reaction slurry is 7 Obtained trimanganese tetraoxide in the same manner as in Example 1. The slurry density of the obtained reaction slurry was 1.261 g / cm ³ .

  The yield of the manganese oxide thus obtained was 98.0%. The experimental conditions and results are shown in Table 1.

The obtained manganese oxide had a tap density of 2.0 g / cm ³ and a BET specific surface area of 0.9 m ² / g. The particle size distribution was monodisperse, the average particle size was 10.1 μm, and the crystal phase was trimanganese tetraoxide consisting of a single phase of trimanganese tetraoxide.

Example 4
Stirring while blowing air so that the oxidation-reduction potential of pure water was 80 mV, adding a 2.8 mol / L sodium hydroxide aqueous solution to the reaction slurry so that the pH of the reaction slurry was 7, and Trimanganese tetraoxide was obtained in the same manner as in Example 1 except that the crystallization was performed with the average residence time of manganese oxide in the slurry being 18 hours. The slurry density of the obtained reaction slurry was 1.146 g / cm ³ .

  The yield of the manganese oxide thus obtained was 92.9%. The experimental conditions and results are shown in Table 1.

The obtained manganese oxide had a tap density of 1.68 g / cm ³ and a BET specific surface area of 1.1 m ² / g. Moreover, the particle size distribution was monodisperse, the average particle size was 9.3 μm, and the crystal phase was trimanganese tetraoxide composed of a single phase of trimanganese tetraoxide.

Example 5
Stirring while blowing air so that the oxidation-reduction potential of pure water is 144 mV, adding a 3 mol / L sodium hydroxide aqueous solution to the reaction slurry so that the pH of the reaction slurry is 7, and in the slurry Trimanganese tetraoxide was obtained in the same manner as in Example 1 except that the crystallization was carried out with an average residence time of the manganese oxide of 18 hours. The slurry density of the obtained reaction slurry was 1.157 g / cm ³ .

  The yield of the manganese oxide thus obtained was 98.5%. The experimental conditions and results are shown in Table 1.

The obtained manganese oxide had a tap density of 1.73 g / cm ³ and a BET specific surface area of 1.3 m ² / g. Further, the particle size distribution was monodisperse, the average particle size was 14 μm, and the crystal phase was trimanganese tetraoxide consisting of a single phase of trimanganese tetraoxide.

Example 6
Stirring while blowing air so that the redox potential of pure water was 89 mV, adding a 2.9 mol / L sodium hydroxide aqueous solution to the reaction slurry so that the pH of the reaction slurry was 7.2, And trimanganese tetroxide was obtained by the method similar to Example 1 except having performed crystallization by making the average residence time of the manganese oxide in a slurry into 9 hours. The slurry density of the obtained reaction slurry was 1.151 g / cm ³ .

  The yield of the manganese oxide thus obtained was 96.3%. The experimental conditions and results are shown in Table 1.

The obtained manganese oxide had a tap density of 1.66 g / cm ³ and a BET specific surface area of 0.9 m ² / g. Moreover, the particle size distribution was monodisperse, the average particle size was 12 μm, and the crystal phase was trimanganese tetraoxide composed of a single phase of trimanganese tetraoxide.

Example 7
Stirring while blowing air so that the oxidation-reduction potential of pure water was 98 mV, adding a 2.9 mol / L sodium hydroxide aqueous solution to the reaction slurry so that the pH of the reaction slurry was 7.2, And trimanganese tetroxide was obtained by the same method as Example 1 except having performed crystallization by making the average residence time of manganese oxide in a slurry into 18 hours. The slurry density of the obtained reaction slurry was 1.154 g / cm ³ .

  The yield of the manganese oxide thus obtained was 98.8%. The experimental conditions and results are shown in Table 1.

The obtained manganese oxide had a tap density of 2.02 g / cm ³ and a BET specific surface area of 0.8 m ² / g. The particle size distribution was monodisperse, the average particle size was 18.5 μm, and the crystal phase was trimanganese tetraoxide consisting of a single phase of trimanganese tetraoxide.

Example 8
Stirring while blowing air so that the redox potential of pure water was 100 mV, and adding a 5.9 mol / L sodium hydroxide aqueous solution to the reaction slurry so that the pH of the reaction slurry was 7.4. Except for this, trimanganese tetraoxide was obtained in the same manner as in Example 1. The slurry density of the obtained reaction slurry was 1.203 g / cm ³ .

  The yield of the manganese oxide thus obtained was 97.0%. The experimental conditions and results are shown in Table 1.

The obtained manganese oxide had a tap density of 2.1 g / cm ³ and a BET specific surface area of 1.1 m ² / g. The particle size distribution was monodisperse, the average particle size was 10.1 μm, and the crystal phase was trimanganese tetraoxide composed of a single phase of trimanganese tetraoxide. In addition, the JIS density of the obtained trimanganese tetraoxide was 2.31 g / cm ³ , which was 1.1 times the tap density.

Example 9
Stirring while blowing air so that the oxidation-reduction potential of pure water was 80 mV, adding a 5.7 mol / L sodium hydroxide aqueous solution to the reaction slurry so that the pH of the reaction slurry was 7.5, And trimanganese tetroxide was obtained by the method similar to Example 1 except having performed crystallization by making the average residence time of the manganese oxide in a slurry into 6 hours. The slurry density of the obtained reaction slurry was 1.203 g / cm ³ .

  The yield of the manganese oxide thus obtained was 99.0%. The experimental conditions and results are shown in Table 1.

The obtained manganese oxide had a tap density of 1.8 g / cm ³ and a BET specific surface area of 1.2 m ² / g. The particle size distribution was monodisperse, the average particle size was 10.1 μm, and the crystal phase was trimanganese tetraoxide consisting of a single phase of trimanganese tetraoxide.

Comparative Example 1
Stirring while blowing air so that the oxidation-reduction potential of pure water was 93 mV, adding a 2.6 mol / L aqueous sodium hydroxide solution to the reaction slurry so that the pH of the reaction slurry was 7, and Trimanganese tetraoxide was obtained in the same manner as in Example 1 except that the crystallization was performed with an average residence time of manganese oxide in the slurry being 9 hours. The slurry density of the obtained reaction slurry was 1.130 g / cm ³ .

  The yield of the manganese oxide thus obtained was 80.8%. The experimental conditions and results are shown in Table 1.

The obtained manganese oxide had a tap density of 1.77 g / cm ³ and a BET specific surface area of 0.7 m ² / g. Moreover, the particle size distribution was monodisperse, the average particle size was 11.0 μm, and the crystal phase was trimanganese tetraoxide consisting of a single phase of trimanganese tetraoxide.

Comparative Example 2
Stirring while blowing air so that the oxidation-reduction potential of pure water was 100 mV, and adding a 0.25 mol / L sodium hydroxide aqueous solution to the reaction slurry so that the pH of the reaction slurry was 7.1. Except for this, trimanganese tetraoxide was obtained in the same manner as in Example 1. The slurry density of the obtained reaction slurry was 1.025 g / cm ³ .

  The yield of the manganese oxide thus obtained was 82.0%. The experimental conditions and results are shown in Table 1.

From the examples and comparative examples, it is possible to obtain manganese trioxide in a high yield of 85% or more, and further 90% or more by crystallizing the slurry density of the reaction slurry to exceed 1.13 g / cm ^3. It could be confirmed. In addition, it was confirmed that the trimanganese tetraoxide obtained by the production method of the present invention has a high filling property, and its particle size distribution is monodispersed and has a uniform particle size.

Claims (2)

A method for producing trimanganese tetraoxide by crystallizing trimanganese tetraoxide from an aqueous manganese salt solution without passing through manganese hydroxide, wherein the slurry density of the slurry containing trimanganese tetraoxide after the crystallization reaction is 1 A method for producing trimanganese tetroxide, comprising a step of crystallizing trimanganese tetroxide exceeding .13 g / cm ³ .   In the said process, a slurry is obtained by mixing manganese salt aqueous solution and alkaline aqueous solution whose alkali concentration exceeds 2 mol / L, The manufacturing method of Claim 1 characterized by the above-mentioned.

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