JPS6330321A - Molybdenum dioxide powder and its production - Google Patents

Abstract

PURPOSE:To produce MoO2 powder which has proper oxygen content and is good in flowability without producing a flocculated block by allowing the powder of MoO3 or 3(NH4)2O.7MoO2.4H2O to fall and reducing it by hydrogen during the fall. CONSTITUTION:MoO3 powder 1 is introduced into a slanted rotary tube 5 via a screw feeder 4 and rotatably allowed to fall in the tube. Simultaneously while maintaining the inside of the rotary tube 5 at about 500-650 deg.C by a heater 7 for about 45min, gaseous hydrogen is injected through an injection port 8 for gaseous hydrogen provided to the tip of the rotary tube 5 and gaseous hydrogen is discharged through a discharge port 9 of a rear end. At this time, MoO3 is reduced by the reaction shown in an equation in the hydrogen atmosphere to produce MoO2 and the generated heat is dissipated by hydrogen and discharged to the outside of the system together with steam through the discharge port 9 for gaseous hydrogen and only MoO2 powder is allowed to fall in a receiver 10 and is obtained as powder good in flowability and also a powder having oxygen content of a narrow range because the reducing reaction is uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to molybdenum dioxide MoO2, which is a raw material for producing fine molybdenum powder, and a method for producing the same.

In particular, the present invention relates to molybdenum dioxide with few agglomerates and good flowability, and a method for producing the same.

[Conventional technology]

Molybdenum dioxide is used as a raw material for fine molybdenum powder with a particle size of 0.5 to 3.0 μm.

As shown in Figure 2, in the conventional method for producing molybdenum dioxide, firstly, molybdenum trioxide MoOs or ammonium molybdate 3(S)2.o.7MoO3.4
H201 is filled into a reduction container (hereinafter referred to as #yjf-2). Next, when the boat 2 is continuously fed into the heating section 3, hydrogen gas is injected from the hydrogen gas inlet 8 into the heating section 3, and the temperature is maintained at 500 to 650°C. Continuous reduction in atmosphere yields molybdenum dioxide.

[Problem that the invention seeks to solve]

However, in the conventional manufacturing method described above.

To fill the coat with molybdenum trioxide, etc.

There is a drawback that the quality varies between the top and bottom of the filled layer.

This is a reduction mechanism.

MoO3+H2→MoO□+H20↑ 3(NH4)20,7M003・4H20+7H2→7
This is because it is an exothermic reaction of MoO2+ 6NH3+ 14H20↑, and the molybdenum dioxide produced by reduction coagulates into hard lumps due to the reaction heat accumulated in the lower part of the packed bed.

Therefore, in the conventional manufacturing method, in the final step,
To obtain molybdenum dioxide powder.

There is the trouble of having to pass through a 60 mesh sieve and loosen the agglomerates.

Furthermore, if molybdenum dioxide hardens and aggregates, the reduction reaction will not proceed, making it impossible to obtain an appropriate oxygen content, resulting in a deterioration in quality.

Furthermore, the flowability deteriorates due to the above-mentioned unevenness in quality such as agglomerates and oxygen content.

There is a problem that it is unsuitable as a raw material for fine molybdenum powder.

On the other hand, in order to eliminate the above-mentioned drawbacks, very complicated control of the reduction temperature, hydrogen flow rate, amount charged into the cage, etc. is required when molybdenum dioxide and ammonium molybdate are reduced.

It is virtually impossible.

In view of the above-mentioned drawbacks, an object of the present invention is to provide a molybdenum diacid with good flowability and a method for producing the same, which can obtain an appropriate oxygen content without forming agglomerates due to reduction. It is.

[Means for solving problems]

According to the present invention, the molybdenum dioxide powder is characterized in that it comprises a falling step of dropping a raw material made of molybdenum trioxide or ammonium molybdate powder, and a reducing step of reducing the raw material with hydrogen while falling. A manufacturing method is obtained.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

The manufacturing method of the present invention using molybdenum trioxide will be explained.

First, as shown in FIG. 1, in the falling process.

Molybdenum trioxide powder 1 prepared in advance is fed into a rotary tube 5 installed at an angle via a screw feeder 4, and rotated and dropped within the chain. At the same time, as a reduction process, the inside of the rotating tube 5 is heated by the heater 7 for 50 minutes.
While maintaining the temperature at 0 to 650°C for 45 minutes, hydrogen gas is injected through the hydrogen gas inlet 8 provided at the tip of the two-rotation tube 5, and hydrogen gas is discharged from the hydrogen gas outlet 9 provided at the rear end. . At this time, molybdenum trioxide.

Through the reaction MoO3+H2→MoO2+H20↑, it is reduced in a hydrogen atmosphere to form molybdenum dioxide. is discharged from the system.

Therefore, only the reduced molybdenum dioxide powder falls into the receiver 10 and is directly obtained as a powder with good flowability, and since the reduction reaction is uniform, the powder has an oxygen content within a narrow range. .

Next, the quality comparison results between the molybdenum dioxide (MoO2) powder obtained by the method of the present invention obtained as described above and that obtained by the conventional method described above will be explained.

(1) Flowability According to the metal powder flow test method in JIS z2502 2 Comparison of the flowability of MoO□ powder obtained by the method of the present invention and MoO2 powder obtained by the conventional method 1Table-1
The results shown are obtained. In addition, in the conventional method.

Since agglomerates of MoO□ were formed, the 60-mesh sieve fraction was measured later.

Table 1 As a result, it was not possible to obtain flowability at all in the conventional method, but in the present invention, flowability was 90 sec/
50, li' or less flowability could be obtained.

(2) Oxygen content and particle size The oxygen content of the MoO□ powder and the particle size of the powder were measured.

In the method of the present invention, the MoO2 powder that fell into the receiver and was collected was sampled from five arbitrary locations and measured. In the conventional method, Mo0 filled in the date
Samples were taken from two locations, the upper part and the lower part of 2, and were measured. One particle size measurement method is the gas adsorption method (BI
It was carried out by T). The measurement results are shown in Table-2.

Margin table below-2 As a result, the oxygen content shows a substantially constant value regardless of the sampling position in the method of the present invention, but in the conventional method, a swell of 0.7 inches or more occurs. .

In addition, the results of particle size measurement of powder 5 In the method of the present invention,
It is recognized that the particles are uniform and fine.

On the other hand, it can be seen that the cited example has non-uniform grains and coarse grains.・Next, as another example of the present invention, (NH4)2 is added to the raw material.
1M00□ powder flowability, oxygen content, BIT measurement values and h MoO3 when using Mo04 powder
The results of comparison with the measured values when using powder are shown in Table 1-3.

Table-3 As a result, as a raw material, 3(NH4) 20.7M00
It was confirmed that good MoO□ powder could be obtained even when 3.4H20 was used.

It will be done.

〔Effect of the invention〕

As explained above, according to the present invention, reduction can be carried out without filling the Tate with molybdenum trioxide or ammonium molybdate powder, regardless of the exothermic reaction during reduction.

Molybdenum dioxide powder can be obtained directly as a powder of uniform particle size with almost no agglomerates.

Moreover, the oxygen content is specified in a narrow distribution range between 24.8 and 26.5% by weight, and the powder flowability is also 90 seconds.
Since it is within ec/50 Ji', molybdenum dioxide powder suitable as a raw material for fine molybdenum powder can be provided.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a reducing device used in an embodiment of the present invention, and FIG. 2 is a schematic diagram of a reducing device used in a conventional example. 1... Raw material, 2... &-to, 3... Heating section, 4...
...Screw feeder, 5...Rotating tube, 7
... Heater, 8... Hydrogen gas inlet, 9... Hydrogen gas outlet. 10...Receptor. Figure 2

Claims (1)

[Scope of Claims] 1. Molybdenum dioxide powder obtained by reducing molybdenum trioxide or ammonium molybdate, characterized in that the flowability of the molybdenum dioxide powder is within 90 sec/50 g. powder. 2. Molybdenum dioxide powder obtained by reducing molybdenum trioxide or ammonium molybdate, the flowability of the molybdenum dioxide powder is within 90 sec/50 g, and the oxygen content is 24.8 to 26. Molybdenum dioxide powder, characterized in that it is 5% by weight. 3. A method for producing molybdenum dioxide powder, which comprises a dropping step of dropping a raw material made of molybdenum trioxide or ammonium molybdate powder, and a reducing step of reducing the raw material with hydrogen while it is falling.