JPS6397354A - Production of spherical low melting metallic grain - Google Patents

Abstract

PURPOSE:To easily and inexpensively obtain fine spherical particles by bringing a nozzle for guiding a molten metal into contact with a water surface or inserting the nozzle into the water and pouring the molten metal continuously into the water without dropping the same, thereby dispersing the molten metal into the water. CONSTITUTION:A device 10 has a vessel 12 for storing the molten metal 11 which is a low melting metal and a water tank 3 for cooling the molten metal 11. The nozzle 14 of a prescribed length is provided in the base of the vessel 12 and the front end of the nozzle 14 is brought into contact with the water surface. A heating means 15 for preventing the solidification of the molten metal 11 is provided to the outside periphery of the vessel 12 and cooling water is stored in a water tank 13 installed below the vessel 12. The water tank 13 is freely vertically movably imposed on a supporting base 18 so that the height of the water surface with respect to the nozzle 14 can be adjusted. The molten metal 11 is continuously poured into the water and dispersed therein without dropping the same, by which the molten metal is spheroidized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for producing spherical metal particles by spheroidizing a low melting point metal such as zinc or cadmium.

[Prior art and problems]

In the process of melting metal alloys, metals with a large surface area are easily melted, so metal 2 alloys are often used in the form of powder or small particles. In addition, since small particles are easy to automate transportation and weighing, they are widely used not only in melting processes but also in various metal processing industries. In addition, the plasto shot method is known as one of the methods for cleaning metal surfaces, and metal particles are used as the projection metal.

Traditionally, as a common method of producing metal grains.

Mechanical crushing method, liquid spraying method, 9-drop method, vaporization condensation method.

Rolling methods, electrolytic methods, etc. have been put into practical use and are used depending on the purpose. Among the above methods, the 2-drop method is.

This is a method in which molten metal is dropped into water through a small hole or nozzle in a container to form particles, and is suitable for producing metal particles with a relatively large particle size.

By the way, the particle size of metal particles obtained by the conventional dropping method is 2 to 10+u+φ, and it is difficult to obtain metal particles having a particle size of about Q, 1 to 2 mm. In addition, the production efficiency is low because the molten metal is dropped drop by drop from the nozzle of the container, etc.
The resulting particles also tend to have irregular shapes, such as depressions on the surface or protruding tips. On the other hand, the liquid spray method and vaporization condensation method are suitable for producing fine particles, but the particles obtained by these methods have a size of several hundred microns, which is too fine. Particles produced by mechanical pulverization have irregular shapes, making it impossible to obtain spherical particles.
Another disadvantage is that the surface is easily oxidized.

[Knowledge about the resolution of inter-sensitivity]

The present inventors attempted to improve the dripping method, and found that when molten metal is injected into water without dripping, in addition to cases in which the injected metal molten metal cools into a rod shape, it also cools into a spherical shape in water immediately after pouring. It was found that there are cases where it is dispersed. Further investigation revealed that the particle size obtained was slightly larger than the nozzle diameter2.
It is spherical.

Particles of 0.3 to 6 mm diameter were obtained for molten zinc.

I found a solution to a conventional problem.

[Structure of the invention]

According to the present invention, when producing metal particles by dropping molten metal into water, the nozzle that guides the molten metal is brought into contact with the water surface or the nozzle is inserted into the water, and the molten metal is continuously flowed without dripping. Provided is a method for producing spherical low melting point metal particles which are made into spheroids by being injected into water and dispersed. Further, in a preferred embodiment, a molten metal of zinc cadmium or indium is used, the nozzle diameter of the container is 0.1 to 4 mmφ, preferably 0.6 to 3 mmφ, the height from the water surface to the bottom of the molten metal is 10 to 200 m7, and the water temperature is 10-80'C is provided.

The figure schematically shows an example of the configuration of an apparatus for carrying out the method of the present invention. are doing. A nozzle 14 of a predetermined length is provided on the bottom of the container 12.
It is provided.

The tip of the nozzle 14 is in contact with the water surface below.

A heating means 15 is provided around the outer periphery of the container 12 to prevent the metal hot water 11 from solidifying. Cooling water is stored in a water tank 16 installed below the container 12. A water supply port 16 is provided at the bottom of the tank 16, and a drain port 17 is provided at the top of the tank.

A constant water temperature is maintained by the inflow and outflow of cooling water inside the tank. The water tank 16 is mounted on a support stand 18 so as to be movable up and down so that the height of the water surface relative to the nozzle 14 can be adjusted.

As shown in the figure, the method of the present invention involves dropping a molten metal of a low melting point metal such as zinc or cadmium or an alloy thereof into water to produce metal particles, by bringing a nozzle that guides the molten metal into contact with the water surface or A nozzle is inserted into the water, and the molten metal is continuously injected into the water without dripping and dispersed to form spheres. The reason why molten metal that continuously flows down into water forms fine spherical particles is not necessarily clear.

The molten metal flowing from the nozzle tip into the water is supported by the nozzle tip due to its surface tension and expands into a fine sphere with a diameter slightly larger than the nozzle diameter.

This is separated from the nozzle tip by the water pressure.

It is presumed that while sinking in water, it is cooled and solidified into a spherical shape, and by repeating this process sequentially, fine spherical particles are formed. In this case, since the molten metal is formed into a spherical shape directly in water, it does not receive the impact of collision with the water surface as in the conventional case, and immediately becomes spherical =! It is then cooled and solidified into a good spherical shape that does not deform. In conventional methods, the nozzle tip is placed at a predetermined height away from the water surface. For this reason, there is a problem in that the hot water droplets dripped from the tip of the nozzle collide with the water surface in a molten state and are easily deformed, but the method of the present invention does not have this problem.

Furthermore, in the method of the present invention, the particle size of the spherical particles is small;
And the formation speed is fast. This means that the nozzle tip touches the water surface,
Alternatively, since the nozzle is inserted into water, the molten metal ball that forms at the tip of the nozzle is subject to water pressure.

This is thought to be because when in air, υ is also subjected to large pressure and becomes spherical, so the particle size is small and it is quickly separated from the nozzle.

The method of the present invention includes the diameter of the nozzle, the height of the hot water from the water surface,
The metal type and temperature of the molten metal, the temperature of the cooling water, etc. are related. The nozzle diameter is especially important.

If it is too thin, the molten metal will become clogged, and if it is too thick, the molten metal will not be dispersed in a spherical shape when it flows down into the water.

Stick-shaped! , hardens. The optimal nozzle diameter range varies depending on the melting point, viscosity, and target particle size of the molten metal.

For example, zinc cadmium and indium are usually 0.
A range of 1 to 4 mmφ, preferably 0.3 to 3 mmφ is suitable. The height of the molten metal from the water surface is related to the melting point of the metal and the nozzle diameter, but in the case of zinc or cadmium, it is
A height of ~200 mm is suitable for the above nozzle diameter. If the position of the molten metal is too high, the pressure applied to the molten metal at the lower end of the nozzle will be high, making it difficult to form a ball. The temperature of the molten metal varies depending on the melting point and viscosity of the metal, nozzle diameter, target particle size, etc. Generally, if the temperature is too high, the viscosity decreases and a narrow nozzle can be used, but cooling becomes insufficient and deformation tends to occur. On the other hand, if the temperature of the molten metal is too low, the viscosity is high and the nozzle diameter must be increased, making it difficult to obtain fine particles with a small diameter of one sphere.

Next, the temperature of the cooling water is preferably 10 to 80°C.

If the temperature exceeds 80°C, cooling of the spherical molten metal will be insufficient.

It becomes easier to deform. If the temperature is 60 to 80°C, the particle surface will become glossy and the finish will be beautiful. Further, if the temperature is 60 to 40°C, the surface becomes matte. If the temperature is lower than 10°C, the molten metal will cool at the tip of the nozzle without becoming spherical, causing problems such as clogging.

Various metals can be used as the molten metal, for example.

Good results have been obtained for zinc, cadmium, and indium. In addition to the zinc base metal and cadmium base metal, zinc-based alloys, tin, or other low-melting point metal alloys can also be suitably used.

〔Effect of the invention〕

According to the method of the present invention, fine spherical particles can be produced easily and at low cost. In the conventional dropping method, the lower limit of the particle size is about 2 φ, and it is difficult to produce particles finer than this. However, according to the method of the present invention: 0
．． Particles with a diameter of 6 to 6 mm can be easily produced. Furthermore, since the nozzle can be inserted into the water, there is no need to worry about adjusting the position of the nozzle from the water surface as in the conventional method, and the process is extremely easy.

Furthermore, the method of the present invention has a practical advantage in that the formation rate of fine particles is fast and is suitable for mass production.

Furthermore, the configuration of the implementation device is also simple.

〔Example〕

Example 1 Uses the purest zinc metal with a zinc purity of 9999.

Using molten zinc melted in advance in a crucible, pour the molten metal into a refractory container with a magnetic tube with an inner diameter of 07 mm attached to the bottom at a length of 5 mm from the bottom to a depth of 100 to 120 mm.
The temperature of the molten metal was maintained at 490 to 510°C by external heating using a gas burner, etc., and the distance between the nozzle tip and the cooling water surface was maintained at 5 mm, and the molten metal was continuously poured from the nozzle into the cooling water at 70 to 80°C. It was poured out and solidified by water cooling to produce spherical zinc particles.

The result is a uniform spherical shape with a particle size of 1.41-2. L+mm
The spherical zinc method was obtained.

The particle size distribution is shown in Table-1.

Table 1: No clogging of the nozzle was observed when the molten metal flowed out.

Example 2 Molten zinc was poured into a nozzle with an inner diameter of 1.5 mm using the same device as in Example 1, and while maintaining the height of the molten metal at 30 to 45 mm, the temperature of the molten metal was raised to 560 mm by external heating with a gas burner. 540℃
Spherical zinc particles were produced in the same manner by maintaining the temperature at 60 to 40° C. and continuously flowing out into cooling water at a temperature of 60 to 40°C. Table 2 shows the particle size distribution of the spherical zinc obtained under these conditions.

Example 6 Using the same apparatus as in Example 1, cadmium ingot (Cd
Spherical cadmium particles were produced under the same conditions as in Example 1 except that the nozzle had a diameter of 0.13 mm and the cooling water temperature was 60 to 40°C.

The particle size distribution of the obtained cadmium particles is shown in: &-6 (-
is. As with zinc, no nozzle clogging was observed when the molten metal flowed out.

Table-3

[Brief explanation of the drawing]

The figure is a schematic diagram showing an example of the configuration of an apparatus for carrying out the method of the present invention. In the drawing, 10-apparatus, 11-molten metal. 12-container, 16-water tank, 14-nozzle. 15-heating means, 16-water supply port, 17-drainage port. 18-Support stand

Claims (1)

[Claims] 1. When producing metal particles by dropping molten metal into water, a nozzle that guides the molten metal is brought into contact with the water surface, or the nozzle is inserted into the water so that the molten metal can be continuously flowed without dripping. A method for producing spherical low-melting point metal particles, which are made into spheroidal particles by injecting them into water and dispersing them. 2 Using molten metal of zinc, cadmium or indium, the nozzle diameter is 0.1 to 4 mmφ, preferably 0.3 to 3 m
The manufacturing method according to claim 1, wherein the height from the mφ water surface to the bottom of the molten metal is 10 to 200 mm, and the water temperature is 10 to 80°C.