JPH0776362B2 - Metal grain manufacturing equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a metal having a constant particle size and shape by adjusting the dropping speed according to the height and temperature of the molten metal when the molten metal is dropped into water to produce metal particles. It relates to a method for producing granules.

[Prior Art and Problems] Conventionally, as a general method for producing metal particles, a mechanical grinding method, a liquid spraying method, a dropping method, a vaporization condensation method, a rolling method, an electrolysis method, etc. are used according to their purposes. Has been done. Among the above methods, the dripping method is a method in which molten metal is dropped into water from a small hole (nozzle) of a container to be granulated. The operation is extremely simple, but the generated particles are It is not as easy as it seems to obtain metal particles having a desired particle size and shape, because it is subtly affected by the drop distance to the water surface, the nozzle hole diameter, the water temperature, and the like.

Under such circumstances, various studies have been made on the setting of the above conditions. For example, the temperature of the cooling water is divided into upper and lower layers, and the upper layer temperature is set to 60 ° C or higher and the lower layer temperature is set to 60 ° C or lower. Method to prevent agglomeration of the dropped particles due to collision in water (JP-A-52-88254), or a method of dropping at a specific hot water temperature, depth, nozzle diameter and water temperature using a ceramic nozzle ( Japanese Patent Publication No. 60-14052) is known.

However, the dropping speed cannot be adjusted by the conventional methods and devices. For this reason, there is a problem that the shape and particle size of the metal particles generated are changed due to changes in the hot water temperature, the hot water depth, and the like while continuing the dropping of the molten metal. Further, there is a problem that the surface is oxidized while the dropped particles reach the water surface and loses metallic luster.

[Findings Related to Problem Solving] The manufacturing apparatus of the present invention makes it possible to adjust the dripping rate of the molten metal and further maintain the temperature of the molten metal by the heating burner, and at the same time, the range from the dropping port of the nozzle to the cooling water surface is the exhaust gas of the heating burner. By maintaining it in a non-oxidizing atmosphere, it is possible to produce high-quality metal particles rich in metallic luster.

[Configuration of the Invention] According to the present invention, there is provided an apparatus for producing metal particles having the following configuration.

(1) A container for storing molten metal, a cooling water tank installed below the container, a dropping nozzle attached to the bottom of the container, and a projecting length adjustable toward the molten metal inlet of the dropping nozzle In the apparatus for producing metal particles provided with a dripping speed adjusting means and a molten metal heating burner, the exhaust gas of the heating burner is guided to the vicinity of the dripping opening of the dripping nozzle so as to maintain the surroundings in a non-oxidizing atmosphere. An apparatus for producing metal particles, characterized in that a heating burner is provided.

(2) A through hole is formed in the center of the container, a heating burner is installed toward the through hole, and a plurality of dropping nozzles are provided around the through hole, while the upper end of the cooling tank is projected near the bottom of the container. At the same time, the manufacturing apparatus according to (1) above, wherein a slit for overflowing the cooling water is provided on the side wall thereof to allow the exhaust gas to stay on the surface of the cooling water.

An example of the manufacturing apparatus according to the present invention is shown in the figure.

The apparatus comprises a molten metal reservoir container 10 and a cooling water tank 11. The container 10 is made of a refractory material for storing the molten metal 12, and a nozzle 13 for dropping the molten metal 12 is provided at the center of the bottom of the container 10. As a concrete material of the container 10 and the nozzle 13, a material having poor wettability with the molten metal 10 is preferably used so as not to cause adhesion of the molten metal 10 and clogging of the nozzle 13, and for example, ceramic or carbon having good workability is used. To be The container 10 may have a cylindrical shape as shown in the figure, and may have a structure in which a nozzle 13 is provided at the center thereof, or a cylindrical inner wall 10a may be provided at the center of the container to form a through hole, and a plurality of nozzles 13 may be provided around the through hole. The structure provided may be sufficient.

An adjusting rod 14 is arranged above the nozzle 13, and a lower end 14a of the adjusting rod 14 faces the melt side inlet 13a of the nozzle 13. The adjusting rod 14 is spring-loaded to reciprocate toward the nozzle 13.
It is elastically supported by frame 15 by 15. The adjusting rod
An adjusting screw 17 for adjusting the protruding length of the adjusting rod 14 is provided above the adjusting rod 14, and the adjusting screw 17 is provided on the frame 16
The lower end 17a thereof is in pressure contact with the upper end 14b of the adjusting rod 14. By protruding the adjusting screw 17 downward, the adjusting rod 14 is pushed down against the elastic force of the spring 15, and the gap between the lower end 14a of the adjusting rod and the nozzle inlet 13a is narrowed to reduce the flow rate. On the other hand, by loosening the adjusting screw 17, the adjusting rod 14 is pushed back upward by the elastic force of the spring 15 and the above-mentioned gap is widened, and the flow rate is increased.

It is preferable to provide a taper between the inflow port 13a of the nozzle 13 and the lower end 14a of the adjusting rod. In the illustrated example, the lower end 14a of the adjusting rod is tapered, and the nozzle inlet 13a is correspondingly formed in a funnel shape. Regarding the shape of the flow path inside the nozzle, it is advisable to form a step inside the nozzle as shown in the drawing and gradually reduce the inner diameters l, m, and n (l>m> n). It is preferably smaller than the flow path length α of the portion. If the nozzle diameters l, m, and n are the same, it is difficult for the molten metal to flow into the nozzle 13. By gradually reducing the nozzle inner diameter, the molten metal can flow smoothly.
The number of steps and the wall thickness can be appropriately determined.

When the nozzle diameter n is small, for example, 3 mm or less, it is preferable to provide a conical taper 13c on the periphery of the dropping port 13b. By forming the taper, the melt can be cut off easily from the dropping port 13b.

Metal particles having the next particle diameter r are formed corresponding to the final nozzle diameter n. (Unit: mm) The distance h from the nozzle dropping port 13b to the cooling water surface is preferably about 1.5 to 2.5 times the target particle diameter r of the metal particles. For example, when n = 2 and r = 4 to 6, it is preferable to set h = 6 to 15 mm. When h ≧ 15, the metal particles become flat, and when h ≦ 6, the nozzle dropping port is clogged due to cooling of the molten metal.

The projection length a of the nozzle 13 to the inside of the molten metal pool container and the projection length b to the outside of the container are appropriately determined. The nozzle 13
There is no particular limitation on the means for attaching the container to the bottom of the container, but if a material having poor wettability with respect to the molten metal is used, the molten metal will not penetrate into the screwed portion even if it is fixed by screwing, so that wetting does not occur. Therefore, there is an advantage that the nozzle can be easily replaced.

Cooling water 20 is stored in the cooling water tank 11, and an overflow gutter 21 is provided on the outer periphery of the upper end of the water tank 11 in order to keep the water surface of the cooling water 20 at a constant height. On the other hand, a cooling water supply port 22 and a metal grain recovery port 23 are provided below the water tank 20.
In order to easily collect the dropped metal particles, the bottom of the water tank 20 is inclined toward the recovery port 23. A bucket 24 for pulling up the metal particles may be attached to the recovery port 23. Of course, other suitable means than the above buckets can be used.

Further, a heating means (burner) is provided in the container in order to maintain the temperature of the molten metal and to maintain the vicinity of the nozzle dropping port in a non-oxidizing atmosphere. In the illustrated embodiment, a through hole is formed in the center of the container 10, and a burner 25 is provided at this portion as the heating means. In this case, burner 25
At the same time when 12 is heated, the exhaust gas is guided to the vicinity of the nozzle to keep the nozzle dropping port warm and to maintain a non-oxidizing atmosphere between the dropping port and the cooling water surface. The upper end 11a of the cooling layer 11
To make the exhaust gas easily stay on the cooling water surface by projecting to near the bottom of the container 10, and forming the cooling water overflow slit 26 at a predetermined position to hold the cooling water surface at a predetermined height. good.

During the production of the metal particles, a predetermined metal hot water 12 such as zinc is stored in the container 10 and the melt 12 is dropped into the water in the cooling water tank 11 through the nozzle 13. At the time of the dropping, the dropping speed of the molten metal is controlled by the adjusting rod 14. For example, when the molten metal temperature is high and the molten metal surface is also high, the viscosity of the molten metal is low and the nozzle
Since the inflow pressure to 13 is also large, the adjusting rod 17
Is slightly projected downward to narrow the gap between the lower end 14a of the adjusting rod and the nozzle inlet 13a, and to slow down the molten metal dropping speed. On the other hand, when the molten metal surface and the molten metal temperature are low, the adjustment rod 14 is slightly pulled up to widen the gap in order to facilitate the inflow of the molten metal into the nozzle port 13.

It should be noted that when the dropping speed is slowed down, the diameter of the metal particles is large, and when the dropping speed is fast, the diameter of the metal particles is small.

Since the dripping rate of the molten metal is affected by the temperature of the molten metal, the burner
The container 10 is heated by 25 to keep the hot water temperature constant. At the same time, the exhaust gas from the burner 25 is guided to the vicinity of the nozzle 13 and the nozzle opening
A non-oxidizing atmosphere is maintained between 13b and the surface of the cooling water to prevent surface oxidation of the dropped metal particles. This can prevent the oxide from adhering to the nozzle dropping port.

As a specific example, in the case of producing zinc particles, the temperature of the hot water of zinc is maintained at 430 to 600 ° C, the cooling water temperature is set to 0 to 80 ° C, the final diameter n of the nozzle is set to 0.3 to 4 mm, and the mixture is dropped by an adjusting rod. By adjusting the speed, the dropping amount per nozzle is adjusted to 5 to 15 kg / hour, preferably 13 kg / hour to produce zinc particles having a particle diameter of 3.00 to 6.00 mm.

[Example] Ten nozzles having a hole diameter of 2 mmφ (final nozzle diameter) are projected 5 mm downward from the bottom surface of a carbon container, and further, a carbon adjustment rod is provided above the nozzle, and a penetrating hole at the center of the container Using a container equipped with a burner in the hole, pre-melted zinc having a purity of 99.99% or more of zinc, which was previously melted in a crucible, is stored in the container, the depth of the hot water is kept at 10 to 150 mm, and the hot water temperature is set to 435 by heating the burner. The temperature was maintained at ˜460 ° C., and the molten zinc was dropped into the water through the nozzle. The distance between the lower end of the nozzle and the cooling water surface is 8 mm. At the same time, the nozzle tip was kept warm by the heat of the burner, and the exhaust of the burner was guided to the above gap to keep the gap in a non-oxidizing atmosphere. When the dropping speed of the molten metal is slowed down, the particle size distribution increases even though the particle size is large, so the dropping speed was adjusted with a control rod so that the desired particle size distribution was obtained.

The particle size distribution of 100 kg of granular zinc obtained by the above operation is as follows, and granular zinc of 4.00 to 5.66 mm could be obtained with a yield of 99.5%.

Most of the obtained zinc particles were spherical, and almost no irregular particles were seen.

When the molten metal flowed out, the dropping rate was constant, and the nozzle was not blocked.

[Effects of the Invention] According to the method and apparatus of the present invention, since the molten metal dropping rate is kept constant by the adjusting rod, metal particles having a uniform particle size and shape can be obtained.

Simultaneously with the heating of the molten metal, a non-oxidizing atmosphere is maintained between the nozzle opening and the water surface, so that surface oxidation of the metal particles is prevented and glossy metal particles are obtained.

By using carbon as the material of the nozzle, a nozzle having good workability can be obtained, and since a nozzle having an arbitrary hole diameter can be used, finer metal particles can be manufactured than before. If the carbon nozzle is made of SiC, it has high strength and is suitable for long-term use.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of an apparatus according to the present invention, FIG. 2 is a sectional view of a container portion thereof, FIG. 3 is a partial sectional view showing another example of the container portion, and FIG. 4 is a nozzle portion. FIG. In the drawing, 10 …… container, 11 …… water tank, 12 …… molten metal, 13 ……
Nozzle, 14 …… Adjustment rod, 15 …… Spring, 16 …… Frame,
17 …… Adjusting screw, 25 …… Burner.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-53-9232 (JP, A) JP-A-56-142805 (JP, A) JP-B-36-13720 (JP, B1)

Claims (2)

[Claims] 1. A container for storing a molten metal, a cooling water tank installed below the container, a dropping nozzle attached to the bottom of the container, and a protruding length of the dropping nozzle toward the molten metal inlet port. In an apparatus for producing metal particles equipped with an adjustable dropping speed adjusting means and a molten metal heating burner, the exhaust gas of the heating burner is guided to the vicinity of the dropping opening of the dropping nozzle to keep the surroundings in a non-oxidizing atmosphere. An apparatus for producing metal particles, wherein a heating burner is provided. 2. A through hole is formed in the center of the container, a heating burner is provided toward the through hole, and a plurality of dripping nozzles are provided around the through hole, while the upper end of the cooling tank is near the bottom of the container. 2. The manufacturing apparatus according to claim 1, wherein the exhaust gas is made to protrude and a side wall of the cooling water is provided with an overflow slit to retain the exhaust gas on the surface of the cooling water.