JPH07103402B2 - Method for producing dustproof active metal powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is widely used in deoxidizing agents for steelmaking, refractory additives, paints, reaction catalysts, metal refining, exothermic agents, fireworks, welding rods and the like. The present invention relates to a method for producing a powder of an active metal such as Ca, Mg, Al, Si, Zr, Ti, Fe or their alloys in a state where dust resistance and explosion resistance are improved without impairing their properties.

[Conventional technology]

When producing powders of these active metals, atomization and mechanical crushing of impellers, stamps, ball mills, etc. are often used, so explosion-proof measures are extremely important in addition to dust prevention.

Dust-proof and explosion-proof measures for treating such active metal powders with strong oxidizing power, which have been conventionally taken, are to treat with a liquid such as oil or ethylene glycol, or to impregnate these liquids with the treated powder sufficiently. It was common practice.

However, depending on the purpose of use, it may be desirable to use it as a dry powder, and as a dust-free treatment method for this purpose, Japanese Patent Publication No.
As described in JP-B No. 55-24481, etc., there is a method in which a granular polytetrafluoroethylene (PTFE) resin is mixed with active metal powder and treated.

[Problems to be solved by the invention]

The above-mentioned PTFE is excellent as a dry powder-type dustproofing agent for metal powders, but it is expensive in itself, and since its addition is also added when pulverization is completed, it is dust in the process of obtaining fine powder. Explosion risk is high.

The object of the present invention is to find a dustproofing agent that is cheaper than the above-mentioned conventional dustproofing agent PTFE, and using the dustproofing agent does not have any adverse effect on the characteristics of the active metal, and yet dust in the micronization process is used. It is an object of the present invention to provide a method for producing a dustproof active metal powder capable of avoiding the danger of explosion.

[Means for solving problems]

As a result of various trial and error, the present invention has found that the above-mentioned objects can be achieved by specifying the addition conditions of powdery-grain polyethylene glycol and polyethylene oxide, which are less expensive than PTFE.

That is, in order to reduce the risk of dust explosion up to the step of dedusting into fine particles, in the step of crushing the active metal, powdered granular polyethylene glycol or polyethylene oxide is added and mixed to this crushed active powder, and further, Dust-proof while crushing raw materials in an inert gas atmosphere.
It enables the use of inexpensive dustproofing agents in place of TFE, and succeeded in developing a dustproofing function in parallel with the progress of explosion-proof pulverization without adversely affecting the characteristics of the active metal with a small addition amount. .

As a matter of course, powdery particulate polyethylene glycol or polyethylene oxide as a dustproof agent can be used together with each other or with other dustproofing agents.

Further, in the present invention, by adding simultaneously a solid fatty acid such as stearic acid or a saponified product thereof together with polyethylene glycol or polyethylene oxide, in addition to the effect of addition of polyethylene glycol or polyethylene oxide in the above-mentioned crushing step, powder It is possible to increase the yield of the powder by reducing the adhesion of the powder to the crusher and the aggregation of the particles.

In the step of crushing the active metal in the step of adding the dustproofing agent powder such as polyethylene glycol or polyethylene oxide, the particle diameter of 15 mm or less is the most efficient in terms of the dustproofing effect, and if the number of coarse particles of 15 mm or more increases 100 The crushing efficiency is too poor to obtain fine powders below the mesh. Although the preferable raw material particle size depends on the crusher selected, a crusher such as an impeller, a stamp or a ball mill is most economical when it has a diameter of 8 mm or less.

Next, the amount of the particulate dust-removing polyethylene glycol and / or polyethylene oxide added is 0.01% of the granular material with respect to 100 parts by weight of the crushed active metal raw material.
It may be used in an amount of up to 0.5 parts by weight, and the appropriate addition amount will vary depending on the crushing model and crushing conditions. Usually, if the amount is less than 0.01 parts by weight, the dustproof effect is weak, and if the amount is more than 0.1 parts by weight, the adhesion and cohesive force is too strong and the discharge and classification become poor or impossible.

Further, in the case of adding 0.05 to 0.5 parts by weight of a solid fatty acid such as stearic acid or a saponified product thereof for improvement thereof, adhesion to a crusher and particles of the same particles are prevented without any inhibition of the dustproof effect of the dustproofing agent. It is possible to effectively prevent agglomeration and improve the yield of the treated powder.

Further, although it is a crushing condition, in the method of the present invention, it is sufficient if there is a time such that 50% or more of 100 mesh or less is obtained by continuously dry crushing a coarsely crushed raw material of 15 mm or less, and thereby, a sufficient dustproof effect can be obtained. A fine powder of active metal can be obtained.

However, under a scanning electron microscope, the added dustproofing agent and the fatty acid described below or its saponified product cannot be clearly identified in the active metal powder composite having a remarkable dustproofing effect, and its mechanism is not clear.

The relationship between the amount of dustproofing agent added and the timing is not particularly limited, and the time necessary for the dustproofing agent to be dispersed throughout is sufficient.

The classification process is not necessary with a crusher equipped with that mechanism, but in the case of unclassified crushed products, classification can be done according to the target particle size. It can be classified with a sieve screen. Since this work is dust-free, it has a good environment and can be carried out safely.

The obtained dustproof powder has a single particle size of 60 mesh or less,
It exhibits a roundish granularity, and the aggregated coarse secondary particle diameter formed by weakly adhering them is 60 mesh or less, and 10
0 mesh or less consists of 98% or more.

〔Example〕

Example 1. Al50.7-at a weight ratio obtained by melting Al and Mg having a purity of 99% or more.
Homemade alloy ingot of Mg 48.9% with a small jaw crusher
The material was roughly crushed to have a diameter of 10 mm or less to prepare a roughly crushed raw material. Next, the Al-
10g polyethylene oxide powder (trade name Alcox R150) manufactured by Meiwa Kasei Co., Ltd. as a dustproofing agent in 2kg of Mg alloy coarsely crushed raw material was placed in a magnetic pot mill with an internal volume of 14 and nitrogen gas was charged to dry it for 10 hours. Crushed. Next, 1.82 kg of the obtained pulverized product was classified with a 100 mesh sieve mesh to obtain 1.60 kg of a powder product having 100 mesh or less. No dust was observed according to the measurement according to the comparative flow test Y.

Example 2. Al50.7-at a weight ratio obtained by melting Al and Mg having a purity of 99% or more.
Homemade alloy ingot of Mg48.0% with a small jaw crusher
The material was roughly crushed to a diameter of 10 mm or less to prepare a roughly crushed raw material. Next, the Al-
2 kg of Mg alloy coarsely crushed raw material, 10 g of polyethylene oxide powder (trade name Alcox R150) manufactured by Meiwa Kasei Kogyo Co., Ltd. and 4 g of granular stearic acid as an anti-dust agent in the internal volume 14
It was put into a porcelain pot mill, and nitrogen gas was charged, followed by dry pulverization for 10 hours.

Then, 1.90 kg of the obtained pulverized material was classified by a 100 mesh sieve mesh to obtain 1.80 kg of a powder product having 100 mesh or less. The obtained product of 100 mesh or less was dust-free in the comparative flow test. This yield was higher than in the case of Example 1.

Example 3 The same home-made alloy ingot as in Example 1 was treated in the same manner and was crushed to a diameter of 10 mm or less to prepare a crushed raw material. Next, 2 g of the Al-Mg alloy coarsely crushed raw material was charged with 10 g of polyethylene glycol powder having a molecular weight of 1200 and 4 g of granular stearic acid in a porcelain pot mill with an internal volume of 14 and charged with nitrogen gas. And pulverized for 4 hours.

Next, 1.90 kg of the obtained pulverized product was classified with a 100 mesh screen to obtain 1.82 kg of a product having 100 mesh or less. No dust was observed according to the measurement according to the comparative flow test Y.

This yield was higher than in the case of Example 1.

Comparative Example As in Example 3, grinding was performed under the same conditions except that polyethylene glycol was removed.

1.91 g of this pulverized product was discharged from the pot mill in the same manner as in Example 3, corresponding to almost the entire amount, but the dust generation during discharge was severe. The product yield of 100 mesh or less obtained in the same manner as in Example 3 was 1.65 kg, but there was no dustproof property in the comparative flow test.

〔The invention's effect〕

By processing the crushing and dedusting of the coarsely crushed raw material in the same process by the method of the present invention, the amount of the dustproofing agent used is reduced and the characteristics of the active metal powder are not lowered at all. It is possible to obtain dust-proof fine powder which can completely prevent dust explosion and eliminate the risk of dust-proof explosion during handling.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shingo Ito 1 289, Furuhashi, Sunan-cho, Motosu-gun, Gifu Prefecture

Claims (2)

[Claims] 1. A 0.01 to 0.5 part by weight of a dustproof agent of powdered polyethylene glycol and / or polyethylene oxide is added to and mixed with 100 parts by weight of the active metal raw material particles at the crushing stage, and 100 mesh under an inert gas atmosphere. The following fine powder is 5
A method for producing a dustproof active metal powder, which comprises continuously dry pulverizing until 0% or more is obtained. 2. To 100 parts by weight of the active metal raw material particles in the crushing stage, 0.01 to 0.5 parts by weight of a particulate polyethylene glycol and / or polyethylene oxide dustproofing agent and 0.05 to 0.5 parts by weight of a solid fatty acid or a saponified product thereof are added. Mix
50% of fine powder of 100 mesh or less under inert gas atmosphere
A method for producing a dustproof active metal powder, which comprises continuously dry pulverizing until the above is obtained.