JP3138548B2 - Activated manganese dioxide for adsorbent and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing activated manganese dioxide for an adsorbent, and proposes an active manganese dioxide having a large specific surface area.

[0002] The above-mentioned manganese dioxide is used for the following applications by taking advantage of its large specific surface area. Adsorbent for air purification: Effective as an adsorbent for removing odors such as mercaptan and amines, and as an adsorbent for harmful gases such as sulfur dioxide. Adsorbent for harmful metals: Effective as an adsorbent for removing these metals from aqueous solutions of heavy metals such as Hg, Cr, and Pb. Adsorbent for valuable metals: L contained in geothermal water, seawater, etc.
It is effective as an adsorbent for recovering valuable metals such as i and Au.

[0003]

2. Description of the Related Art Conventionally, methods for producing manganese dioxide (powder) include a method of electrolyzing a manganese sulfate solution, a method of heating manganese oxide in the presence of oxygen, and a method of heating manganese nitrate. I have. However, these conventional methods mainly focus on simply obtaining manganese dioxide, and are manufactured through processes such as mechanical pulverization and oxidative heating. Also, it was impossible to process the particle surface into a complicated shape. As a result, the specific surface area (BET value) is 30 to 40.
The limit was about m ² / g.

On the other hand, as a prior art for obtaining fine manganese oxide, Japanese Patent Application Laid-Open No. 63-210029 proposes a method of blowing oxygen into a molten ferromanganese.
However, manganese oxide produced under this method is mainly manganese tetroxide (Mn ₃ O ₄ ), not manganese dioxide (MnO ₂ ). Therefore, conventionally, manganese oxide (Mn
By subjecting ₃ O ₄ ) to heat treatment in an oxidizing atmosphere,
Although a method of forming manganese dioxide has been considered, in this method, the shape of the particle surface does not change much and the specific surface area (BET value) is at most 1 even though the particle size is satisfactory.
It was found that the improvement was only about 5 m ² / g.

[0005]

As a result, each of the above prior arts could not produce manganese dioxide having a large specific surface area, which is fine and has numerous projections on the surface of the particles. An object of the present invention is to propose a method for producing active manganese dioxide having a small particle size and a large specific surface area, which is suitable as an adsorbent for special gases and heavy metals.

[0006]

In order to solve the above-mentioned problems, the present invention provides a method for producing manganese dioxide having the following features. That is, oxygen or a gas containing oxygen is blown into a molten iron-manganese alloy. Fine particles generated when melted
Substantially spherical in, the manganese oxide having an average particle diameter of 0.1 to 5 [mu] m, hydrochloric acid, sulfuric acid, nitric acid, either at least one or more acids of acetic acid and hydrofluoric acid was added, dissolving the Mn ²⁺ component and other impurity components・ By removal , the average particle size is 0.1
Mainly spherical Mn ⁴⁺ component of ~ 5 μm, remaining on the surface
Specific surface area (BET
Activated manganese dioxide having a value of 50 m ² / g or more.
A method for producing activated manganese dioxide for an adsorbent, which is characterized by being produced, is proposed.

[0007]

According to the present invention, a manganese oxide or the like generated when a medium- to low-carbon ferromanganese is melted from a high-carbon ferromanganese in a converter is used as a raw material, and the manganese oxide raw material is converted into Mn ²⁺ by an acid such as sulfuric acid. This is a method for dissolving and removing components and impurity components. That is, according to the method for producing manganese dioxide according to the present invention produced using such a raw material, according to the investigation and measurement by the inventors, depending on the properties of the starting material regardless of the production conditions, Spherical fine powder containing manganese dioxide as a main component, an average particle diameter of 0.1 to 5 μm, an almost spherical shape having countless projections on its surface, and a specific surface area (BET value) of 50 m ² / g or more is obtained.

As described above, the activated manganese dioxide produced as described above uses, as a starting material, manganese oxide generated by blowing oxygen or a gas containing oxygen onto the molten ferromanganese. The reason for using such raw materials is
This manganese oxide raw material is extremely fine spherical particles having an average particle diameter of 0.1 to 5 μm, and its main component is trimanganese tetroxide. This is because only the Mn ²⁺ component corresponding to / 3 dissolves, and the Mn ⁴⁺ component has the property of remaining as particles having countless projections. That is, this increases the specific surface area of manganese dioxide. In addition, since the powder is originally fine, a pulverizing step is not required, so that a high-purity powder can be produced without the risk of contamination with impurities.

Next, the acid used for dissolving the manganese oxide raw material is 1 wt% or more, and any of hydrochloric acid, sulfuric acid, nitric acid, acetic acid, and hydrofluoric acid can be used as long as the amount is equal to or more than the mole of manganese oxide. One type or a mixture of two or more types may be used, and the concentration thereof may be arbitrarily selected. This acid treatment is carried out at normal temperature and pressure for about 1 hour, preferably at 50 ° C. or more for 4 hours or more. And after this acid treatment, you may filter and neutralize with an alkali solution further.

[0010]

EXAMPLE 1 250 g of 23% sulfuric acid was gradually added to 250 g of manganese oxide produced during the production of a low-carbon ferromanganese converter and heated at 60 ° C. for 4 hours with stirring, followed by filtration. Again, the insoluble matter after filtration is
1250 g of sulfuric acid was added, and the same operation was repeated. The insoluble material was neutralized with an alkaline solution, and then filtered and washed again.
Dried at 0 ° C. Table 1 shows the chemical composition of the activated manganese dioxide powder thus obtained, and Table 2 shows the particle size distribution.
And the specific gravity and specific surface area (BET value) are shown in Table 3. 1 and 2 show electron micrographs (× 20000) of the raw material manganese oxide and the activated manganese dioxide obtained here, respectively.

[0011]

[Table 1]

[0012]

[Table 2]

[0013]

[Table 3]

[0014]

As described above, the manganese dioxide produced according to the present invention has a large specific surface area due to having numerous projections on the surface of the ultrafine particles, and therefore has a large air purification such as deodorization and heavy metal. detoxification of waste water containing, Li from geothermal water or sea water, the recovery of such as Au valuable metals, other general adsorbent is preferably used in the effective of fields. Moreover,
Manufacture is extremely easy because manganese oxide generated during ferromanganese melting is used as a starting material.

[Brief description of the drawings]

FIG. 1 is an electron micrograph showing the particle shape of a raw material manganese oxide.

FIG. 2 is an electron micrograph showing the particle shape of a product manganese dioxide.

Continuation of the front page (72) Inventor Yoji Michi 5-9-1-6 Tokodai, Tsukuba-shi, Ibaraki Nippon Heavy Chemical Industry Co., Ltd. Central Research Laboratory Tsukuba Research Laboratory (56) References JP-A-61-14137 (JP, A) JP-A-62-148326 (JP, A) JP-A-63-210029 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C01G 45/02 CA (STN)

Claims (1)

(57) [Claims] 1. A fine , substantially spherical manganese oxide having an average particle size of 0.1 to 5 μm, which is produced when smelting a molten iron-manganese alloy by blowing oxygen or a gas containing oxygen. Is added with at least one of hydrochloric acid, sulfuric acid, nitric acid, acetic acid and hydrofluoric acid to dissolve and remove the Mn ²⁺ component and other impurity components, so that the average particle size is 0.1 to 0.1 %.
5μm predominantly spherical, undissolved Mn ⁴⁺ component on the surface
Specific surface area (BET value) due to having numerous projections
There method of manufacturing an adsorbent for activated manganese dioxide, characterized by producing <br/> activated manganese dioxide is 50 m ^{2 /} g or more.