JPH05208825A - Production of manganese hydroxide - Google Patents

Abstract

PURPOSE:To industrially produce manganese hydroxide even by adoption of a mild condition by reaction in a relatively short time by using manganese sulfate as a raw material. CONSTITUTION:An aqueous solution of manganese sulfate is added to an aqueous solution of ammonia while introducing oxygen gas or an oxygen-containing gas to the aqueous solution of ammonia. In the operation, the temperature of the aqueous solution of ammonia is set at 40-80 deg.C, the concentration of ammonia in the aqueous solution of ammonia is set >= four times (ratio of mol concentration) that of manganese sulfate in the aqueous solution of manganese sulfate and addition rate of the aqueous solution of manganese sulfate to n¦¦X¦¦ volume aqueous solution of ammonia is set at <=1.5n-volume, especially <=0.3n-volume/hr.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for industrially producing manganese hydroxide using manganese sulfate and ammonia as raw materials.

[0002]

2. Description of the Related Art Manganese hydroxide, which is useful as a raw material for soft ferrite, has been conventionally manufactured by the following method.

In Japanese Patent Application Laid-Open No. 50-80297, 0.05.
A method for producing manganese hydroxide is described in which aqueous ammonia and aqueous hydrogen peroxide are simultaneously added little by little to an aqueous manganese sulfate solution having a concentration of up to 3.0 mol.

In Japanese Patent Laid-Open No. 59-223236, a slurry obtained by adding aqueous ammonia to an aqueous solution of manganese sulfate is used as a high-purity manganese compound (the main component is hydrothermally heated at high temperature and high pressure in the presence of oxygen gas). (Manganese hydroxide) is shown.

[0005]

Problems to be Solved by the Invention JP-A-50-8029
The method of Japanese Patent Publication No. 7 uses expensive hydrogen peroxide, and also uses a relatively large amount of hydrogen peroxide (in the example, equivalent amount or more, especially 5 times equivalent amount or more, relative to the amount of manganese ion). However, it has the disadvantage of high cost. In addition, there is an industrial disadvantage that it is necessary to leave the mixture in the air for aging for about 50 hours after the reaction, that is, to perform a long-time post-treatment by air oxidation.

The method disclosed in Japanese Patent Laid-Open No. 59-223236 requires high temperature (20 to 200 ° C., 150 ° C. in the embodiment) and high pressure (10 to 30 kg / cm ² ). It is also disadvantageous.

In addition, since the methods of the above-mentioned JP-A-50-80297 and JP-A-59-223236 are methods of reacting by adding aqueous ammonia to an aqueous solution of manganese sulfate, they are added to the produced manganese hydroxide. There is a problem that sulfate radicals that cause facility corrosion tend to remain.

Against this background, the present invention makes it possible to obtain manganese hydroxide in a relatively short reaction time while using manganese sulfate as a raw material and employing mild conditions such as low temperature and normal pressure. The purpose is to provide an industrial method.

[0009]

The method for producing manganese hydroxide according to the present invention comprises the steps of: (1) reacting an aqueous manganese sulfate solution with an aqueous ammonia solution and oxidizing them to produce manganese hydroxide; Alternatively, add an aqueous solution of manganese sulfate while blowing an oxygen-containing gas, and (2) raise the temperature of the aqueous ammonia solution to 40 to 80 ° C.
(3) The ammonia concentration in the aqueous ammonia solution is set to 4 times or more the molar concentration of manganese sulfate in the aqueous manganese sulfate solution (by molar concentration ratio), (4) The aqueous solution of manganese sulfate in an n-volume aqueous ammonia solution. The addition rate of
It is characterized in that it is carried out so as to satisfy all the conditions of setting to 1.5 n volume / hr or less.

The present invention will be described in detail below.

The manganese sulfate aqueous solution, which is one of the raw materials of the present invention, can be obtained, for example, by crushing ferromanganese to dissolve it in sulfuric acid and separating and removing the floating carbon. The manganese sulfate aqueous solution thus obtained is used after adjusting the concentration with water as needed. Although the concentration of manganese sulfate in the manganese sulfate aqueous solution is not particularly limited, it is industrially set to about 1 to 2 mol / liter.

An aqueous ammonia solution is used as the other raw material. It is necessary to set the concentration of ammonia in the aqueous ammonia solution to at least 4 times (in molar concentration ratio) the concentration of manganese sulfate in the aqueous solution of manganese sulfate. When the ammonia concentration is lower than this range, the product contains a large amount of other manganese compounds such as trimanganese tetraoxide as impurities. Although the upper limit of the concentration of the aqueous ammonia solution is not limited, it is often up to about 8 times in consideration of handling.

The temperature of the aqueous ammonia solution is set to 40 to 80 ° C. When the temperature is lower than 40 ° C., the reaction rate becomes slow and manganese compounds other than the target substance are mixed, while when the temperature exceeds 80 ° C. Has a high vapor pressure, which increases the amount of ammonia scattered at the time of blowing oxygen gas or oxygen-containing gas, and is also disadvantageous in terms of thermal energy. The aqueous solution of manganese sulfate can be kept at a temperature similar to that of the aqueous ammonia solution, but a temperature lower than that (for example, normal temperature) is also acceptable.

In the reaction, it is necessary to add the manganese sulfate aqueous solution while blowing oxygen gas or oxygen-containing gas into the ammonia aqueous solution. When an aqueous solution of manganese sulfate is added to the aqueous solution of ammonia and reacted, and then oxygen gas or an oxygen-containing gas is blown in, a manganese compound other than manganese hydroxide is produced.

The amount of oxygen or oxygen-containing gas blown in is
The amount is sufficient for oxidation to manganese hydroxide. As the oxygen-containing gas, for example, air which has been subjected to PSA (pressure fluctuation adsorption separation) to have an oxygen gas concentration higher than that of normal air is used, and in some cases, air can also be used.

In the present invention, it is important to add an aqueous solution of manganese sulfate to the aqueous solution of ammonia, and when the aqueous solution of ammonia is added to the aqueous solution of manganese sulfate, the content of sulfate radicals in the produced manganese hydroxide is increased. Manganese compounds other than manganese hydroxide are produced.

The addition rate of the aqueous manganese sulfate solution to the aqueous ammonia solution must be set to 1.5 n volume / hr or less, where n is the volume of the aqueous ammonia solution. When the addition rate exceeds 1.5 n volume / hr, the product contains manganese compounds other than manganese hydroxide. The smaller the addition rate of the manganese sulfate aqueous solution is, the higher the purity of manganese hydroxide is, which is preferable, and the most preferable result is obtained particularly in the case of 0.3 n volume / hr or less. The lower limit of the addition rate of the manganese sulfate aqueous solution is not particularly limited, but 0.1% is added considering productivity.
It is advantageous that the volume is n volume / hr or more.

The manganese hydroxide obtained by the above-mentioned method is used in various applications of conventionally used manganese hydroxide,
Particularly useful as a raw material for soft ferrite.

[0019]

In the present invention, contrary to the conventional method, a method of adding an aqueous ammonia solution to a manganese sulfate aqueous solution is adopted. Moreover, at that time, the manganese sulfate aqueous solution is added while blowing the oxygen gas or the oxygen-containing gas into the ammonia aqueous solution.

The temperature of the aqueous ammonia solution is 40 to 8
Not only is the temperature set to 0 ° C., but the ammonia concentration in the aqueous ammonia solution is set to a specific range in relation to the concentration of manganese sulfate in the aqueous manganese sulfate solution, and the addition rate of the aqueous manganese sulfate solution to the aqueous ammonia solution is set to a specific range. is doing.

By organically combining such conditions, manganese sulfate is used as a raw material, and mild conditions are adopted, but high-grade manganese hydroxide containing almost no sulfate radicals is used for a relatively short time. It could be obtained by reaction.

[0022]

EXAMPLES The present invention will be further described with reference to examples.

Example 1 While blowing oxygen gas into 2 liters of an aqueous ammonia solution having a concentration of 7.5 mol / liter heated to 60 ° C., the concentration was increased.
2 l of 1.5 mol / l manganese sulfate aqueous solution was added over 4 hours to obtain a precipitate.

The obtained manganese compound was found to be acicular manganese hydroxide (MnOOH) by X-ray diffraction analysis and electron micrograph (SEM photograph). The sulfate content was also low at 0.18% by weight.

Example 2 While blowing oxygen gas into 2 liters of an aqueous ammonia solution having a concentration of 7.5 mol / liter heated to 60 ° C., the concentration was increased.
2 l of a 1.5 mol / l manganese sulfate aqueous solution was added over 2 hours to obtain a precipitate.

The obtained manganese compound was found to be acicular manganese hydroxide (MnOOH) by electron micrograph. However, it contained some trimanganese tetraoxide. The content of sulfate was as low as 0.12% by weight.

Comparative Example 1 Aqueous ammonia solution 2 having a concentration of 3.5 mol / liter at 25 ° C. 2
After adding 2 liters of an aqueous solution of manganese sulfate having a concentration of 1.5 mol / liter to 1 liter to form a precipitate, oxygen gas was blown into the mixture to oxidize it.

The sulfate content of the obtained manganese compound is
Although it was low at 0.09% by weight, X-ray diffraction analysis revealed that this manganese compound was not manganese hydroxide.

Comparative Example 2 An aqueous ammonia solution having a concentration of 3.5 mol / liter was added to 2 liters of an aqueous solution of manganese sulfate having a concentration of 1.5 mol / liter heated to 60 ° C. while blowing oxygen gas so that the pH of the aqueous solution became 8. And a precipitate was obtained.

The obtained manganese compound was mainly trimanganese tetraoxide, and the content of sulfate group was 0.90% by weight.

Comparative Example 3 2 liters of a 3.5 mol / liter aqueous ammonia solution was added to 2 liters of a 1.5 mol / liter aqueous solution of manganese sulfate heated to 60 ° C. to form a white precipitate, and then oxygen gas was added. It was blown in and oxidized.

The obtained manganese compound was mainly trimanganese tetraoxide, and the sulfate group content was as large as 1.05% by weight.

Comparative Example 4 While blowing oxygen gas into 2 liters of an aqueous ammonia solution having a concentration of 3.5 mol / liter heated to 60 ° C., the concentration was increased.
2 l of a 1.5 mol / l manganese sulfate aqueous solution was added over 2 hours to obtain a precipitate.

As a result, a manganese compound having a sulfate group content of 0.09% by weight was obtained, but the manganese compound was found to be trimanganese tetraoxide by X-ray diffraction analysis.

Comparative Example 5 While blowing oxygen gas into 2 liters of an aqueous ammonia solution having a concentration of 3.5 mol / liter heated to 60 ° C., the concentration was increased.
2 L of a 1.5 mol / L manganese sulfate aqueous solution was added over 45 minutes to obtain a precipitate.

As a result, a manganese compound having a sulfate group content of 0.10% by weight was obtained, but the manganese compound was found to be trimanganese tetraoxide by X-ray diffraction analysis.

[0037]

When the method of the present invention is carried out, an aqueous solution of manganese sulfate is used as a raw material, and mild conditions are adopted,
High-quality manganese hydroxide containing almost no sulfate can be produced in a reaction in a relatively short time.

Claims (2)

[Claims] 1. When reacting an aqueous manganese sulfate solution with an aqueous ammonia solution and oxidizing them to produce manganese hydroxide, (1) adding an aqueous manganese sulfate solution while blowing oxygen gas or oxygen-containing gas into the aqueous ammonia solution. , (2) Set the temperature of the aqueous ammonia solution to 40 to 80 ° C, (3) Set the ammonia concentration in the aqueous ammonia solution to at least 4 times (in molar concentration ratio) the concentration of manganese sulfate in the aqueous manganese sulfate solution. (4) A method for producing manganese hydroxide, characterized in that the addition rate of the manganese sulfate aqueous solution to the n volume ammonia aqueous solution is set to 1.5 n volume / hr or less, and the above conditions are all satisfied. 2. The production method according to claim 1, wherein the addition rate of the manganese sulfate aqueous solution to the n volume ammonia aqueous solution is set to 0.3 n volume / hr or less.