JP4000389B2 - Metal grain manufacturing method and manufacturing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for producing metal particles used for replenishing metal ions in a plating bath or for surface treatment such as shot blasting.
[0002]
[Prior art]
Methods for producing metal particles include a dripping method, a liquid spray method, a vaporization condensation method, a rolling method, a mechanical grinding method, and an electrolysis method, which are performed according to the shape, particle size, etc. of the target metal particle. ing.
Among the methods for producing the metal particles, the dropping method is provided with a nozzle for dropping molten metal at the lower part of the molten metal holding container, and a cooling medium such as water is placed below the nozzle, The molten metal is discharged from the nozzle and dropped into the cooling medium below to form metal particles.
This dripping method is a production method capable of relatively easily producing metal particles that are favorably used as a raw material for plating, for example.
[0003]
There are two methods for granulating metal particles by the dropping method: a method in which molten metal is dropped from a nozzle provided in a container containing molten metal and dropped into a cooling medium to cool and solidify; and the molten metal is linearized. There is a method of dropping into a cooling medium, dividing it by the liquid pressure of the cooling medium to form droplets, and then cooling and solidifying.
The former is applied when producing metal particles having a relatively large particle size, and the latter is applied when producing metal particles having a relatively small particle size, and the shapes of nozzles used are different.
Manufactured by changing the state of molten metal discharged from the nozzle from a droplet shape to a linear shape or from a linear shape to a droplet shape while continuing to produce metal particles using one type of nozzle. Since the shape and particle size of the metal particles change in an unstable manner, the metal particles are usually produced in one of the tapping conditions.
[0004]
When metal particles are produced in the form of droplets or linear hot water, when the hot water from the nozzle starts or when the nozzle temperature drops for some reason and the metal solidifies in the nozzle, the nozzle is Heating is performed with a burner or the like to start hot water and eliminate metal solidification.
[0005]
[Problems to be solved by the invention]
As described above, the dropping method is a production method useful for producing metal particles.
However, the drop method according to the prior art has a particle size range of metal particles that can be manufactured with one kind of nozzle, where the shape of the metal particles may be unstablely changed to a wire shape, a petal shape, a flat shape, or the like. There are problems such as narrowness and the possibility of metal solidification in the nozzle, which has been a problem from the viewpoint of quality assurance and productivity.
[0006]
Therefore, the problem to be solved by the present invention is to stably produce metal particles having a stable shape, particularly metal particles having a spherical particle shape having high operability in the subsequent process with high productivity over a wide particle size range. It is an object of the present invention to provide a metal grain manufacturing method and a manufacturing apparatus that can be manufactured.
[0007]
[Means for Solving the Problems]
The first means for solving the above-described problem is that the molten metal held in the molten metal holding container is transferred from the nozzle provided in the molten metal holding container into the cooling medium provided below the nozzle. A method for producing metal particles that drops and solidifies by cooling to produce metal particles having a desired shape and particle size,
The temperature of the nozzle;
An interval between the tip of the nozzle and the cooling medium,
It is a method for producing metal particles, characterized in that it is controlled so as to have a predetermined value.
[0008]
By the first means, it has become possible to produce metal particles having a desired shape and particle size.
This is because the temperature of the nozzle fluctuates due to the temperature of the molten metal passing through the nozzle, the amount of passage, etc., and as a result of this nozzle temperature fluctuation, the temperature of the molten metal passing through the nozzle this time passes The amount of the nozzle etc. fluctuated, and the fluctuation of the nozzle temperature under the influence of this fluctuation was avoided by the configuration in which the nozzle temperature was controlled to a predetermined value, and the tip of the nozzle and the cooling medium By changing the interval of the above to a predetermined value by changing the interval of the molten metal due to the evaporation of the cooling medium when cooling and solidifying the molten metal that has dropped, the desired shape and particle size are avoided. It is possible to produce metal grains having
Furthermore, by adopting a configuration in which the temperature of the nozzle is controlled to a predetermined value, it is possible to prevent the metal from solidifying in the nozzle.
[0009]
The second means is the method for producing metal particles according to the first means,
A temperature measuring means for measuring the temperature of the nozzle;
Using a heating means for heating the nozzle,
In the method for producing metal particles, the temperature of the nozzle is controlled by the heating unit based on the temperature of the nozzle measured by the temperature measuring unit.
[0010]
According to the second means, when the temperature of the nozzle fluctuates due to the influence of the temperature of the molten metal passing through the inside, the amount of passage, etc., the fluctuation is measured by the temperature measuring means for measuring the temperature of the nozzle. It was possible to control the temperature of the nozzle to a predetermined value by controlling the heating means for heating and heating the nozzle according to the temperature measurement result.
[0011]
The third means is the method for producing metal particles according to the first or second means,
Measuring means for measuring the distance between the tip of the nozzle and the cooling medium;
Using an interval control means for controlling the interval between the tip of the nozzle and the cooling medium,
The method for producing metal particles, wherein the distance control means controls the distance between the nozzle tip and the cooling medium based on the value of the distance between the nozzle tip and the cooling medium measured by the measuring means. It is.
[0012]
According to the third means, when the distance between the tip of the nozzle and the cooling medium fluctuates due to evaporation of the cooling medium when cooling and solidifying the molten metal that has fallen, this fluctuation is measured, and the measurement result is By controlling the gap between the nozzle tip and the cooling medium, the gap between the nozzle tip and the cooling medium could be controlled to a predetermined value.
[0013]
A 4th means is a manufacturing method of a metal grain given in either of the 1st-3rd means,
The metal particles are zinc particles or zinc alloy particles, wherein the metal particles are produced.
[0014]
The fourth means makes it possible to produce zinc particles or zinc alloy particles having a desired shape and particle size.
[0015]
The fifth means is an apparatus for producing metal particles, which drops molten metal onto a cooling medium and cools and solidifies it to produce metal particles,
A molten metal holding container for holding the molten metal;
A nozzle provided in the molten metal holding container, for dropping the molten metal;
Heating means for heating the nozzle;
A temperature measuring means for measuring the temperature of the nozzle;
A measuring means provided below the nozzle and measuring a distance between a cooling medium that cools and solidifies the molten metal falling from the nozzle to form metal particles, a tip of the nozzle, and the cooling medium;
An interval control means for controlling an interval between the tip of the nozzle and the cooling medium;
According to the temperature value of the nozzle measured by the temperature measuring means, temperature control of the nozzle by the heating means is performed,
By controlling the gap between the nozzle tip and the cooling medium by the gap control means from the value of the gap between the nozzle tip and the cooling medium measured by the measuring means, it has a desired shape and particle size. An apparatus for producing metal particles, characterized by producing metal particles.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of a metal grain manufacturing apparatus according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view of an embodiment of a manufacturing apparatus used for manufacturing metal particles according to the present invention. A molten metal holding container 10 (hereinafter referred to as a container 10) is made of metal particles. It is a container for storing and holding the molten metal 20 as a raw material, and a graphite or ceramic crucible or the like is preferably used.
[0017]
A nozzle 40 is fitted and provided at an appropriate location on the lower wall surface or bottom surface of the container 10.
The nozzle 40 has a funnel-shaped outer shape, for example, and is provided in the lower part of the container 10 as described above. At this time, the lower part 45 of the nozzle is provided in a form protruding downward from the container 10.
[0018]
A passage through which the molten metal 20 passes is provided in the nozzle 40.
As a preferable configuration example of this passage, in order from the upper side of the nozzle 40, the same as the introduction passage 41 opened to the bottom of the container 10, the first passage 42 having a smaller diameter than the introduction passage 41, and then the first passage 42. Some have a second passage 43 having a larger diameter or a larger diameter, and a nozzle tip 44 which is the end of the second passage 43.
Here, as the nozzle 40, for example, a “molten metal dropping nozzle” described in Japanese Patent No. 1743916 can be suitably applied.
As the material of the nozzle 40, the molten metal 20 and carbon or ceramics having good wettability are preferably used.
[0019]
In the lower part 45 of the nozzle described above, the heater 30 is installed as a heating means, and the temperature of the nozzle is controlled by appropriately heating the lower part 45 of the nozzle to keep it at a desired temperature.
The heater 30 may be anything as long as the nozzle temperature can be controlled and maintained at a desired temperature. For example, a sheathed type in which the periphery of the heater wire 31 is covered with an insulating material 32 and further covered with a stainless steel sheath. An electric heater or the like is preferable.
What is necessary is just to install this heater 30 by means, such as winding around the lower part 45 of a nozzle.
[0020]
A temperature measuring sensor 35 is installed in the lower portion 45 of the nozzle as a temperature measuring means, and the temperature of this portion is appropriately measured. And based on this temperature measurement result, the heating to a nozzle can be easily controlled by controlling the electric power supplied to the heater 30. In addition, it is also preferable that this control part is automatically controlled using a CPU or the like.
As the temperature measuring sensor 35, a resistance temperature detector, a thermocouple or the like is preferably used.
[0021]
Below the nozzle tip 44, the cooling medium 60 is placed in the cooling medium tank 61 with a distance d, and in the vicinity of the nozzle 40, the distance between the nozzle tip 44 and the cooling medium 60 is measured. A level sensor 63 as a measuring means is provided to measure the distance d between the nozzle tip 44 and the cooling medium 60. Further, an elevating mechanism 62 is installed in the cooling medium tank 61 as an interval control means, and is connected to a level sensor 63.
When the interval d changes due to evaporation of the cooling medium 60 or the like as the metal grain manufacturing process proceeds, the level sensor 63 detects this change and controls the elevating mechanism 62 to set the interval d to a desired constant value. keep.
[0022]
The elevating mechanism 62 only needs to be able to control the distance d, and is an elevating mechanism that mechanically raises and lowers the cooling medium tank 61, and a pump that raises and lowers the liquid level by adjusting the amount of the cooling medium 60 in the cooling medium tank 61. A mechanism or the like can be applied.
The accuracy of the interval control is preferably ± 2 mm or less, and more preferably ± 1 mm or less.
As the cooling medium 60, water or the like is preferably used.
[0023]
Next, the manufacturing process of a metal grain using this metal grain manufacturing apparatus will be described.
First, as the molten metal 20 accommodated in the container 10, a metal such as zinc, aluminum, copper, magnesium, iron, lead, tin, cadmium, or an alloy containing two or more metals can be used.
For example, when zinc or a zinc aluminum alloy (zinc 96 wt%, aluminum 4 wt%, magnesium 0.04 wt%) is used as the molten metal 20, the purity of zinc is higher than that of distilled zinc metal of 98.5% or more. The purest zinc ingot of purity, etc. can be used in good numbers. And the preferable temperature of the molten zinc in the container 10 is 380-600 degreeC, More preferably, it is 450-550 degreeC.
[0024]
The molten metal 20 stored in the container 10 moves by its own weight to the introduction passage 41 in the nozzle 40, passes through the first passage 42 and the second passage 43, and is discharged from the tip 44 of the nozzle.
At this time, the temperature of the lower portion 45 of the nozzle is determined as a total of the outside air temperature, the temperature of the molten metal 20, the amount of the molten metal 20 passing through the nozzle 40, and the heating by the heater 30.
In the nozzle having the first passage 42 and the second passage 43 having a larger diameter, when the temperature of the lower portion 45 of the nozzle is low, the first passage 42 leads to the second passage 43. When the hot metal is poured out, the viscosity of the molten metal rises to form droplets due to the surface tension. After passing through the second passage 43 in this state, the molten metal is discharged from the tip 44 of the nozzle into the form of droplets. Falls as a hot spring metal 50.
On the other hand, when the temperature of the lower portion 45 of the nozzle is high, the molten metal discharged from the first passage 42 to the second passage 43 does not form a droplet here, but passes through the second passage, From the front end 44, the hot water is discharged into a linear shape, and the discharged hot metal 50 is dropped.
[0025]
Accordingly, in the present invention, the temperature and shape of the tapping metal 50 discharged from the nozzle tip 44 is controlled by controlling the heating by the heater 30 while measuring the temperature of the nozzle bottom 45 temperature. Can be appropriately selected.
[0026]
By adopting the above configuration, even if only one nozzle is used, the shape of the tapping metal 50 can be selected either in the form of droplets or in a line by simply controlling the power supplied to the heater 30. It became.
As a result, although the details will be described later, the width of the particle size of the metal particles that can be produced by one nozzle could be greatly widened.
[0027]
Furthermore, by controlling the temperature of the nozzle by controlling the electric power supplied to the heater 30, it is possible to freely control the start of pouring of the hot metal 50 at the tip 44 of the nozzle at the start of production of metal particles.
As a result, the lower part 45 of the nozzle can be accurately carried out while measuring the temperature rising process to raise the temperature to the temperature necessary and sufficient for the start of the hot water and the production of metal particles having a desired shape and particle size. Productivity in metal particle production can be increased.
In addition, heating of the lower part 45 of the nozzle by a gas burner or the like, which is necessary in the prior art, is no longer necessary, the thermal deterioration of the nozzle 40 is suppressed, and the life is extended, so that the manufacturing cost can be reduced. became.
[0028]
Incidentally, when zinc or zinc aluminum alloy zinc (96 wt%, aluminum 4 wt%, magnesium 0.04 wt%) is used as the molten metal 20, the temperature of the lower portion 45 of the nozzle is controlled by controlling the electric power supplied to the heater 30. It is preferable to set it as the range of -450 degreeC.
What happens is that the temperature of the lower part 45 of the nozzle is 250 ° C. and the hot water at the tip 44 of the nozzle starts, a hot water in the form of droplets is obtained at 250 to 380 ° C., and a linear hot water is obtained at 380 to 450 ° C. However, when the temperature is 450 ° C. or higher, the shape of the manufactured zinc particles becomes unstable.
[0029]
The hot metal 50 discharged from the tip 44 of the nozzle falls into the cooling medium 60 with a gap d from here, but when the hot metal 50 is in the form of droplets, it becomes the metal particles 55 in the cooling medium 60 as it is, When the tapping metal 50 is linear, after falling into the cooling medium 60, it is divided by the liquid pressure of the cooling medium into metal particles 55.
The distance d from the nozzle tip 44 to the cooling medium 60 is preferably controlled at ± 2 mm in the range of 0 to 20 mm, more preferably controlled at ± 1 mm in the range of 5 to 15 mm. .
[0030]
Incidentally, when the tapping metal 50 is in the form of droplets, it is possible to obtain a metal particle 55 having a large particle size of about 3 to 8 mm. When the tapping metal 50 is in the form of a line, the metal particle 55 having a small particle size of 3 mm or less. Can be obtained.
From the above, it is possible to easily control the start timing of the zinc particle hot water and the state of the hot water by only temperature control by the heating means for the heater 30 while using one nozzle.
[0031]
(Example 1)
Zinc having a purity of 99.99% was used as a raw material metal.
The temperature of the molten zinc in the molten metal holding container was set to 450 to 550 ° C.
The nozzle is based on the “nozzle for molten metal dropping” described in Japanese Patent No. 1743916, and the shape of the passage for molten zinc is the introduction passage (diameter: 14φ, length: 85 mm), the first passage. (Diameter: 0.8φ, length 8mm), the second passage (diameter: 1.0φ, length: 12mm). The material of the nozzle is Si ₃ N ₄ .
The nozzle heating means is fixed by winding a sheath type heater having a capacity of 300 W around the lower part of the nozzle.
The temperature measuring means for measuring the temperature at the lower part of the nozzle is fixed by winding a thermocouple around the lower part of the nozzle.
The level sensor uses an ultrasonic sensor and measures the distance between the tip of the nozzle and the cooling solvent. Then, the cooling medium tank was moved up and down by a lifting mechanism using hydraulic pressure so that the measured distance between the tip of the nozzle and the cooling solvent kept a preset value.
[0032]
When energization of the heater was started and voltage control of the energization power was performed, when the temperature of the lower portion of the nozzle reached 250 ° C., hot water for molten zinc started from the nozzle tip.
Here, while controlling the temperature of the lower part of the nozzle, the electric power supplied to the heater was subjected to voltage control, and the nozzle lower part temperature was set to 415 ° C.
Next, the interval d between the nozzle tip and the cooling medium was set with an accuracy of ± 1 mm within the range of 0 to 22 mm shown in FIG. The cooling medium was water and the temperature was 50 ° C.
FIG. 1 shows the zinc discharge from the nozzle tip, the shape of the zinc particles, and the particle size distribution obtained as a result.
[0033]
From this result, it was found that spherical zinc particles can be obtained when the distance d between the nozzle tip and the cooling medium is in the range of 0 to 15 mm.
In particular, when the distance d between the nozzle tip and the cooling medium was in the range of 8 to 10 mm, it was possible to produce with a particle size distribution in which spherical particles of zinc having a particle size of 2 to 4 mm accounted for 90% or more.
[0034]
(Example 2)
The same zinc, nozzle, heating means, temperature measuring means and interval adjusting means as in Example 1 were used, and the temperature of the molten zinc in the molten metal holding container was also set to 450 to 550 ° C. as in Example 1.
The distance d between the nozzle tip and the cooling medium was 10 mm, and was set with an accuracy of ± 1 mm. The cooling medium was water and the temperature was 50 ° C.
[0035]
When energization of the heater was started and voltage control of the energization power was performed, when the temperature of the lower portion of the nozzle reached 250 ° C., hot water for molten zinc started from the nozzle tip.
Here, the electric power supplied to the heater was controlled while measuring the temperature of the lower part of the nozzle, and the temperature of the lower part of the nozzle was set to each temperature shown in FIG. FIG. 2 shows the state of zinc discharged from the nozzle tip, the shape of the zinc particles, and the particle size distribution obtained as a result.
[0036]
From this result, it has been found that zinc particles having a spherical particle shape can be produced in a temperature range of 250 to 450 ° C. at the lower portion of the nozzle. Moreover, it turned out that the particle size of the zinc particle which can be manufactured using one type of nozzle covers a wide range of 8 to 2 mm or less. In particular, when the temperature at the bottom of the nozzle was 415 ° C., it could be produced with a particle size distribution in which 90% or more of spherical zinc particles having a particle size of 2 to 4 mm account for 90% or more.
[0037]
(Example 3)
A zinc-aluminum alloy tapping state from the nozzle tip was produced in the same manner as in Example 2 except that a zinc-aluminum alloy (96 wt%, aluminum 4 wt%, magnesium 0.04 wt%) was used as a raw material metal. The shape and particle size distribution of zinc-aluminum alloy grains were measured.
[0038]
When the energization of the heater was started and the voltage of the energizing power was controlled, when the temperature of the lower part of the nozzle reached 220 ° C., the hot water of molten zinc-aluminum alloy started from the tip of the nozzle.
Here, the electric power supplied to the heater was controlled while measuring the temperature at the lower part of the nozzle, and the temperature at the lower part of the nozzle was set to each temperature shown in FIG. FIG. 3 shows the molten state of the zinc-aluminum alloy from the nozzle tip, the shape of the zinc particles, and the particle size distribution obtained as a result.
[0039]
From this result, it has been found that spherical zinc-aluminum alloy grains can be produced when the temperature at the bottom of the nozzle is in the range of 220 to 420 ° C. Moreover, it turned out that the particle size of the zinc-aluminum alloy grain manufactured using one kind of nozzle covers a wide range of 8 to 2 mm or less. In particular, at a temperature of 390 ° C. at the lower portion of the nozzle, it could be produced with a particle size distribution in which spherical particles of zinc-aluminum alloy having a particle size of 2 to 4 mm account for 90% or more.
[0040]
(Comparative Example 1)
Zinc having a purity of 99.99% similar to that in Example 1 was used as the raw material metal, and the temperature of the molten zinc in the molten metal holding vessel was set to 450 to 550 ° C.
The same nozzle as in Example 1 was used, but no heater was installed below the nozzle.
The distance d between the nozzle tip and the cooling medium was 30 mm, and was set with an accuracy of ± 1 mm. The cooling medium was water and the temperature was 50 ° C.
[0041]
The lower part of the nozzle was heated with a gas burner, and molten zinc hot water was started from the nozzle tip.
FIG. 4 shows the state of zinc discharged from the nozzle tip, the shape of the zinc particles, and the particle size obtained as a result.
From this result, when the heater heating of the nozzle lower part was not performed, the state of the hot water from the nozzle was a dripping state, and the particle size of the obtained zinc particles was 4 to 5 mm. In addition, the particle shape is not only spherical but also a lot of hemispherical, tear-like, etc. are mixed.
Further, in Comparative Example 1, the new nozzle was used, but the tip of the nozzle was blocked about 3 hours after the start of pouring, and the pouring was stopped.
In order to restart the hot water, it was necessary to heat the lower part of the nozzle with a gas burner again.
[0042]
(Comparative Example 2)
A nozzle with a modified passage shape through which molten metal passes was manufactured. The shape of the passage through which the molten metal passes in this prototype nozzle is shown in FIG.
Using this prototype nozzle, zinc particles were produced under the same conditions as in Comparative Example 1.
FIG. 5 shows the state of zinc discharged from the nozzle tip, the shape of the zinc particles, and the particle size obtained as a result.
[0043]
Also in Comparative Example 2, a new nozzle was used as a prototype nozzle. However, the nozzle tip was blocked in about 3 hours after the start of pouring, the pouring was stopped, and in order to resume the pouring, the lower part of the nozzle was again connected to the gas burner. It was necessary to heat with.
From this result, when the heater heating of the lower part of the nozzle was not performed, even if the shape of the passage through which the molten metal in the nozzle passes was changed, the hot water state from the nozzle was in a dripping state, and the obtained zinc particle size Was 4-5 mm. Moreover, the shape of the particles was not only spherical but also many hemispherical, tear-like, etc. were mixed.
[0044]
【The invention's effect】
In the production of metal particles in which molten metal is dropped into a cooling medium from a nozzle provided in a holding container to produce metal particles, the temperature control of the nozzle and the interval between the tip of the nozzle and the cooling medium are spaced apart. By controlling, it became possible to produce metal particles having a desired shape and particle size.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of an example of an apparatus for producing metal particles according to an embodiment of the present invention.
FIG. 2 is a table showing zinc tapping state, grain shape, and particle size distribution in Example 1.
FIG. 3 is a table showing zinc tapping state, grain shape, and particle size distribution in Example 2.
4 is a table showing the tapping state, grain shape, and particle size distribution of a zinc alloy in Example 3. FIG.
FIG. 5 is a table showing the zinc tapping state, grain shape, and grain size in Comparative Example 1;
FIG. 6 is a table showing the zinc tapping state, grain shape, and grain size in Comparative Example 2;
[Explanation of symbols]
10. Molten metal holding container 20. Molten metal 30. Heater 35. Sensor for temperature measurement 40. Nozzle 44. Nozzle tip 45. Lower part of nozzle 50. Hot metal 55. Metal grain 60. Cooling medium 61. Cooling medium tank 62. Elevating mechanism 63. Level sensor d. Distance between nozzle tip and cooling medium

Claims (6)

The molten metal held in the molten metal holding container is dropped from a nozzle provided in the molten metal holding container into a cooling medium provided below the nozzle to be cooled and solidified, thereby obtaining metal particles having a desired particle size. A method for producing metal grains, comprising:
The nozzle has an upper passage and a lower passage connected to the upper passage, the lower passage has a structure having a larger diameter than the upper passage, and has a heating means for heating the nozzle. Use
By controlling the temperature of the lower part of the nozzle by the heating means, when the molten metal is discharged from the upper passage to the lower passage, the molten metal is made into a droplet shape or a linear shape, and then discharged from the tip of the nozzle. The manufacturing method of the metal grain characterized by the above-mentioned. It is a manufacturing method of the metal grain according to claim 1.
A method for producing metal particles, comprising controlling an interval between a tip of the nozzle and the cooling medium. It is a manufacturing method of the metal grain according to claim 1 or 2,
A method for producing metal grains, characterized in that the molten metal passing through the lower passage is discharged in a linear form.   4. The method for producing metal particles according to claim 1, wherein the metal particles are zinc particles or zinc alloy particles. 5. A metal particle manufacturing apparatus that drops molten metal onto a cooling medium and cools and solidifies it to produce metal particles,
A molten metal holding container for holding the molten metal;
A nozzle that is provided in the molten metal holding container and has an upper passage and a lower passage connected to the upper passage, and the lower passage has a diameter wider than that of the upper passage;
And a heating means for heating the lower part of the nozzle . The metal grain manufacturing apparatus according to claim 5, further comprising a measuring unit that measures a distance between the tip of the nozzle and the cooling medium.

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