JP2005199239A - Method and device for producing fine particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method and device which enable the sure production of fine particles with a desired uniform particle size by a downsizable simple construction. <P>SOLUTION: The device for producing fine particles is equipped with an orifice 5 through which a melt liquid 7 is discharged and caused to fall down, a pipe 3 which has a small-diameter section 11 at the halfway position and inside which the discharged melt liquid 7 falls down together with an air current, and an alternating-current magnetic field application means 9 which is placed in the small-diameter section 11 and applies an alternating-current magnetic field to the melt liquid 7 falling down. In the method for producing fine particles with the device, while being accelerated by the air current, the melt liquid 7 just falling down inside the small-diameter section 11 is divided into a particle state by the application of an alternating-current magnetic field and then solidified, yielding fine particles. From immediately after the melt liquid 7 is divided into a particle state to yield liquid droplets 12, the loci of the liquid droplets 12 falling down are changed every moment, enabling liquid droplets 12 to be prevented from coalescing with each other. Thus, fine particles capable of being downsized and having a desired uniform particle size can be surely produced. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a manufacturing method and a manufacturing apparatus for manufacturing microparticles of a uniform size from a molten liquid, and more particularly to a manufacturing method and a manufacturing apparatus for microparticles that are preferably used for manufacturing silicon particles used in a photoelectric conversion device. Is.

  In the development of solar cells, market needs such as performance efficiency, resource finiteness, manufacturing cost, etc. are being developed. As one of the promising solar cells, one using a photoelectric conversion element using granular silicon has been actively developed.

  As a production device for producing fine particles with high crystallinity, such as granular silicon, used for photoelectric conversion elements of solar cells stably and efficiently, and at low cost, for example, by discharging molten liquid from holes There is a manufacturing apparatus that manufactures microparticles by dropping and solidifying the molten liquid while dropping (for example, see Patent Document 1).

  In addition, until now, as a method for producing fine particles of uniform size, by applying regular vibration to the molten liquid of the raw material discharged from the holes, the molten liquid is subjected to a knot-like deformation at regular intervals. There is known a method of generating and solidifying the deformation by spontaneous growth by the action of the surface tension of the molten liquid.

  As means for applying vibration to the molten liquid in this method, there are means for vibrating the holes, means for irradiating the molten liquid discharged from the holes with a sound wave having a certain frequency (see, for example, Patent Document 2). ).

  However, in the conventional method for producing microparticles, the droplets generated by dividing the molten liquid fall one after another in a state of being very close to each other, so that the droplets have a uniform size from the molten liquid. Even if it is divided, there is a problem that in the subsequent dropping process, the droplets coalesce into droplets of different sizes, and the size of the finally produced microparticles is uneven. It was.

  In order to solve this problem, a container having a hole in the peripheral wall is rotated at high speed so that the molten liquid discharged from the hole is regularly vibrated and the molten liquid is discharged radially. Has been proposed (see Patent Document 3).

According to the method of applying a regular vibration to the molten liquid discharged from the hole and generating droplets toward the periphery of the container while rotating the container having the hole in the peripheral wall portion, the container rotates, Since the molten liquid is discharged radially from the holes in the peripheral wall portion, the generated liquid droplets follow different parabolic trajectories, so that the coalescence of the liquid droplets can be effectively prevented and uniform. That is, it is possible to obtain microparticles of various sizes.
JP 2003-128493 A U.S. Pat.No. 5,445,666 JP-A-5-154425

  However, in the case where droplets are generated in the method of producing fine particles while rotating a container having a hole in the peripheral wall while applying regular vibration to the molten liquid discharged from the hole, a radial pattern is generated around the container. The droplets discharged in the air will scatter over a wide range around the rotating container, but the drop process of this droplet also serves as a cooling process to solidify the droplet, so the droplet is falling The manufacturing apparatus for carrying out this manufacturing method needs to secure a droplet drop area with a sufficient width so that the manufacturing apparatus is enlarged as a result. There was a point.

  In addition, in order to produce microparticles having a diameter of less than 1 mm, the diameter of the holes for generating droplets is as small as that. However, if the diameter of the hole is reduced, the surface tension of the molten liquid discharged from the hole is increased, and it becomes difficult to discharge the liquid. There was a problem that it was necessary to make it extremely high.

  For example, in the case of producing silicon microparticles as a granular semiconductor used in a photoelectric conversion device, it is necessary to suppress the material cost of silicon and secure the minimum thickness necessary for light absorption. The size is as small as about 300 μm in diameter. In order to rotate such a container at a high speed while applying a high pressure to the container, a large-scale device is required and the cost is increased.

  The present invention has been devised in view of the problems in the prior art as described above, and its purpose is to reliably produce fine particles of uniform size with a simple configuration that can be reduced in size. It is providing the manufacturing method and manufacturing apparatus of the microparticle which can be performed.

  In the method for producing fine particles of the present invention, the molten liquid is discharged from the hole and dropped inside the tube arranged in the vertical direction together with the air flow, and a small diameter portion is provided in the middle of the tube, and the molten liquid is supplied to the small diameter portion. An alternating magnetic field applying means for applying an alternating magnetic field is disposed in a transverse direction, and the molten liquid falling is applied to the small diameter portion while being accelerated by the air flow and separated into particles after being solidified after being solidified. It is characterized by making it a microparticle.

  Moreover, the method for producing fine particles of the present invention is characterized in that, in the above configuration, the AC magnetic field applying means is disposed above the small diameter portion.

  Further, in the method for producing fine particles of the present invention, in each of the above configurations, a second AC magnetic field applying unit that applies a second AC magnetic field in a direction crossing the molten liquid that is falling is disposed above the small diameter portion. Then, the second AC magnetic field is applied to the molten liquid that is falling.

  The apparatus for producing microparticles of the present invention is arranged in the vertical direction, provided with a hole for discharging and dropping the molten liquid and a small-diameter portion provided in the middle for dropping the discharged molten liquid together with the air flow inside. An AC magnetic field applying means for applying an AC magnetic field in a direction crossing the falling direction to the falling molten liquid provided in the small-diameter portion is provided.

  Moreover, the apparatus for producing microparticles according to the present invention is characterized in that, in the above configuration, the AC magnetic field applying means is disposed above the small diameter portion.

  In addition, in the above-described configuration, the apparatus for producing fine particles according to the present invention includes a second AC magnetic field applying unit that applies a second AC magnetic field in a direction across the molten liquid that is falling above the small diameter portion. It is characterized by that.

  According to the method for producing fine particles of the present invention, the molten liquid is discharged from the hole and dropped inside the pipe arranged in the vertical direction together with the air flow, and a small diameter part is provided in the middle of the pipe, and the molten part is provided in the small diameter part. After arranging an alternating magnetic field applying means for applying an alternating magnetic field in a direction across the liquid and separating the molten liquid falling into a granular shape by applying the alternating magnetic field while accelerating by the air flow in the small diameter portion Since it is made into fine particles by solidifying, the magnetic field in the direction crossing the molten liquid can be changed every moment in the small diameter part, and Lorentz changing every moment in the direction crossing the direction in which the molten liquid falls in the small diameter part Since the force can be continuously applied, the granular molten liquid immediately after being divided can be dispersed in different directions every moment. In addition, since the molten liquid is dropped together with the air flow inside the pipe, the flow velocity of the air flow is increased in the small diameter portion, so that the molten liquid is separated and dispersed in a granular manner in the direction crossing the direction of falling by the alternating magnetic field. At the same time, it is accelerated in the direction of falling by the air flow with increased flow velocity, and a speed difference is generated between the granular molten liquid trying to catch up from the upstream side. Can be reliably prevented, and fine particles having a desired uniform size can be stably obtained.

  In addition, according to the method for producing microparticles of the present invention, in the above configuration, when the alternating magnetic field applying means is disposed above the small diameter portion, the molten liquid that has reached the small diameter portion is first subjected to the alternating magnetic field applied by the alternating magnetic field applying means. After receiving the action, it reaches the region where the flow velocity of the airflow is fast, so that the molten liquid is dispersed in granular form by the alternating magnetic field in the upper part of the small diameter portion and then accelerated in the direction of falling by the airflow with increased flow velocity. Therefore, coalescence of the granular molten liquid can be more effectively prevented, and fine particles having a desired uniform size can be obtained more stably.

  Furthermore, according to the method for producing microparticles of the present invention, in each of the above-described configurations, the second AC magnetic field applying means for applying the second AC magnetic field in the direction across the falling molten liquid is provided above the small diameter portion. When the second alternating magnetic field is applied to the falling molten liquid, the molten liquid before reaching the small diameter portion has a period different from or equal to the alternating magnetic field in the small diameter portion by the second alternating magnetic field. Since it can be vibrated at a desired constant period, it can give a constant period of disturbance to the molten liquid before falling into the small diameter part, and more easily and reliably at the desired uniform diameter at the small diameter part. The molten liquid can be separated into sizes, and fine particles with a uniform size can be stably generated. In addition, the apparatus can be miniaturized because the molten liquid can be separated into particles even at an earlier stage before the molten liquid reaches the small diameter portion. Furthermore, since the position where the molten liquid is separated into particles and becomes droplets can be determined more accurately by the second AC magnetic field applying means and the AC magnetic field applying means of the small diameter portion, the position design of the small diameter portion can be made. It can be done easily.

  According to the apparatus for producing microparticles of the present invention, the hole for discharging and dropping the molten liquid, and the discharged molten liquid are dropped together with the air flow inside, provided with a small diameter part in the middle, arranged in the vertical direction. And an alternating magnetic field applying means for applying an alternating magnetic field in a direction crossing the falling direction to the falling molten liquid provided in the small diameter portion, so that the molten liquid falls in the small diameter portion. The Lorentz force that changes from moment to moment in the direction across the surface can be easily applied, and the molten liquid can be easily accelerated by increasing the flow velocity of the airflow in the falling direction at the small diameter portion. Is separated and dispersed in granular form every moment in the direction crossing the falling direction, and the velocity between the granular molten liquids separated by the air flow with increased flow velocity in the small diameter part Can be reliably prevented coalesce to cause, it can be stably obtained fine particles of the desired uniform size.

  Further, according to the apparatus for producing microparticles of the present invention, in the above configuration, when the AC magnetic field applying means is disposed above the small diameter portion, the molten liquid is dispersed in a granular form by the AC magnetic field above the small diameter portion. After that, it is accelerated in the direction of falling by the air flow with increased flow velocity, so that coalescence of the granular molten liquid can be prevented more effectively, and the desired uniform size of fine particles is more stable Can be obtained.

  Furthermore, according to the apparatus for producing fine particles of the present invention, in each of the above-described configurations, the second AC magnetic field applying means for applying the second AC magnetic field in the direction crossing the falling molten liquid is disposed above the small diameter portion. In this case, it is possible to easily give a constant period of disturbance to the molten liquid before falling into the small diameter portion, so that the molten liquid is more easily and reliably separated into a desired uniform size in the small diameter portion. Therefore, fine particles having a uniform size can be stably generated. Further, since the molten liquid can be easily started to be separated into particles even at an earlier stage before the molten liquid reaches the small diameter portion, the apparatus can be reduced in size. Furthermore, since the position where the molten liquid is separated into particles and becomes droplets can be determined more accurately by the second AC magnetic field applying means and the AC magnetic field applying means of the small diameter portion, the position design of the small diameter portion can be made. It can be done easily.

  Hereinafter, the manufacturing method and manufacturing apparatus of the granular particle | grains of this invention are demonstrated in detail, referring drawings.

  FIG. 1 is a cross-sectional view showing a schematic configuration in an example of an embodiment of a production apparatus for using the method for producing fine particles of the present invention.

  An apparatus 100 for producing microparticles of the present invention shown in FIG. 1 is arranged in a vertical direction, provided with a gas inlet 1 and a gas outlet 2, a pipe 3 provided with a small diameter portion 11 in the middle, and a melt A container 4 that holds the liquid 7, a nozzle member 6 that is provided at the bottom of the container 4 and has a hole 5 that discharges the molten liquid 7, and a molten liquid 7 that is disposed on the side surface of the container 4 and is filled in the container 4. And a second alternating magnetic field applying means 10 disposed above the small diameter portion 11 and a second alternating magnetic field applying means 10 disposed above the small diameter portion 11.

  The gas inlet 1 and the gas outlet 2 are for inflowing and exhausting the gas as the air flow in order to generate an air flow in the pipe 3, and the gas inlet 1 is a small diameter portion 11 of the pipe 3. The gas outlet 2 is installed on the downstream side. Further, the gas inlet 1 is installed at a position where gas does not blow directly onto the molten liquid 7 so that the flow of the molten liquid 7 discharged from the hole 5 of the container 4 is not disturbed, and the gas outlet 2 is connected to the pipe 3. It is preferable to install it on the bottom surface. Further, it is desirable that the air flow generated by the gas is a laminar flow.

  As a gas used for generating an air flow in the tube 3 for producing fine particles, helium, argon, xenon, etc. may be used because it is harmless and has low reactivity with the molten liquid 7. Among them, it is preferable that the momentum for accelerating the droplet is large, that is, the mass number is as large as possible, and that it is inexpensive, and argon is preferable from this viewpoint.

  In addition, the air flow generated by the gas in the tube 3 generates uniform droplets 12, so it is desirable not to disturb the flow of the molten liquid 7 immediately after being discharged from the hole 5, and a laminar flow is generated in the tube 3. It is desirable to do so.

  The tube 3 for dropping the molten liquid 7 discharged from the holes 5 together with the air flow has sufficient heat resistance against the heat of the heater 8 for heating the molten liquid 7 and also does not disturb the air flow. It is desirable that the seam is kept airtight from the outside using an O-ring or gasket. Quartz, alumina ceramics, stainless steel or the like can be used as a member constituting the tube 3. Further, the small diameter portion 11 provided in the middle of the pipe 3 has a high height that can efficiently separate the molten liquid 7 falling through the small diameter portion 11 into a granular shape by the alternating magnetic field applying means 9 and the air flow that increases the flow velocity at the small diameter portion 11. It is installed in the position.

  It is desirable that the small-diameter portion 11 has a laminar flow in this portion so as not to disturb the flow of the molten liquid 7, and the diameter thereof is gradually reduced as much as possible so that no turbulent flow occurs. Is preferred. Further, although the dispersed droplets 12 spread in the horizontal direction, it is desirable to set the diameter of the small diameter portion 11 so that the dispersion width does not exceed the diameter of the small diameter portion 11.

  The container 4 for holding the molten liquid 7 discharged from the hole 5 has sufficient heat resistance that allows the molten liquid 7 to be heated by the heater 8 and held in a good molten state, and considers the reactivity with the molten liquid 7. It is desirable that it is made of a material. For example, if the molten liquid 7 is silicon, the container 4 made of aluminum oxide, silicon carbide, graphite or the like can be used to prevent the components of the container 4 from being mixed into the molten liquid 7 and to deteriorate. Therefore, it can be used for a long time.

The nozzle member 6 installed at the bottom of the container 4 prevents the wear of the hole 5 provided through the center of the nozzle member 6 and discharges the molten liquid 7 in a stable state to generate granular particles. It is desirable to use a material excellent in heat resistance and wear resistance. For example, silicon carbide having a true specific gravity of 3.0 g / cm ³ or more, cubic boron nitride of 3.30 g / cm ³ or more, 3.35 g / cm It is desirable to consist of any of ^three or more diamonds. Further, when the nozzle member 6 is formed of any one of single crystal silicon carbide, single crystal aluminum oxide (sapphire), single crystal cubic boron nitride, and single crystal diamond, the wear of the holes 5 is further improved. It is possible to generate granular particles by discharging the molten liquid 7 in a stable state. The nozzle member 6 using these materials is formed by processing a single crystal or a sintered body whose density is set according to sintering conditions.

  The hole 5 of the nozzle member 6 is for discharging the molten liquid 7 in the container 4 and dropping it in the tube 3. To obtain microparticles of a desired size from the molten liquid 7, for example, It is desirable that the diameter is 5 μm or more and 100 μm or less. It is difficult to form the holes 5 to be less than 5 μm with the current processing technology, and it is necessary to apply a large pressure to the container 4 in order to discharge the molten liquid 7. Will be invited. If the diameter of the hole 5 is less than 5 μm, the particle size of the droplet 12 formed by separating the molten liquid 7 discharged from the hole 5 into particles is too small. For example, when the particle is crystalline silicon In this case, there is a problem that the size is too small, such as the solar light absorption efficiency of the photoelectric conversion device using the granular crystalline silicon particles is deteriorated. On the other hand, when the diameter of the holes 5 exceeds 100 μm, the size of the droplets 12 obtained by separating the discharged molten liquid 7 into particles and the fine particles obtained therefrom become large, and the fine particles in a good crystalline state Tend to be difficult to obtain.

  The hole 5 in the nozzle member 6 may be processed by machining, laser processing, ultrasonic processing, or the like. At this time, it is desirable to form the inner wall of the hole 5 so as to be smooth.

  In addition, it becomes possible to replace only the nozzle member 6 by producing the container 4 and the nozzle member 6 by a separate member, and making it the structure which assembles them. As a result, if the hole 5 is worn or clogged, the replacement becomes easy, and the normally expensive container 4 body can be used continuously without replacement.

  As the raw material to be the molten liquid 7, all materials having conductivity in the liquid state can be used. For example, in addition to various metals, a semiconductor material having high conductivity in a liquid state, such as silicon or germanium, can be used.

  As the heater 8 that is disposed on the side surface of the container 4 and heats the molten liquid 7 filled in the container 4, an induction heating type or resistance heating type heater may be used.

  The AC magnetic field applying means 9 disposed in the small diameter portion 11 of the tube 3 is normally a coil, and separates the molten liquid 7 into granular droplets 12 at the small diameter portion 11 to prevent the combination of these droplets 12. It functions as a coil for separation and coalescence prevention, for example, a conductor wire or conductor tube made of copper or the like wound in a spiral shape with a diameter of about 5 cm and a length of about 5 cm. The AC magnetic field applying means 9 generates an AC magnetic field by flowing an AC current through the conductor, and applies an AC magnetic field in a direction crossing the falling direction of the molten liquid 7.

  The AC magnetic field applied to the AC magnetic field applying means 9 is, for example, an AC magnetic field generated by a sinusoidal AC current of about 3 kHz when the flow rate of the molten liquid 7 discharged from the hole 5 is about 10 m / s. And it is sufficient.

  The AC magnetic field applying means 9 is preferably arranged as high as possible in the small diameter portion 11. By disposing the alternating magnetic field applying means 9 on the upper portion of the small diameter portion 11, the molten liquid 7 is separated into particles by applying the alternating magnetic field by the alternating magnetic field applying means 9 in a direction crossing the falling direction of the molten liquid 7. For the droplets 12 generated in this way, the acceleration area in the falling direction after being separated by the air flow whose flow velocity is increased at the small diameter portion 11 can be set longer, so that the coalescence of the droplets 12 can be prevented. Can enhance the effect.

  Note that the AC magnetic field applying means 9 may be disposed below the small diameter portion 11, but in that case, the molten liquid 7 is separated by the AC magnetic field applying means 9 into a granular shape by the air current in the small diameter portion 11. Since it is accelerated in the falling direction, the effect of preventing the coalescence of the droplets 12 tends to be somewhat low.

  The second AC magnetic field applying means 10 disposed above the small diameter portion 11 of the tube 3 is usually a coil. When the molten liquid 7 is separated into particles by the small diameter portion 11, the molten liquid 7 is separated. It functions as a coil for facilitating separation, and is formed by, for example, winding a conductor wire or a conductor tube such as copper in a spiral shape with a diameter of about 5 cm and a length of about 5 cm.

  The second alternating magnetic field applied to the second alternating magnetic field applying means 10 is, for example, a sine wave of about 3 kHz when the flow rate of the molten liquid 7 discharged from the hole 5 is about 10 m / s. What is necessary is just to set it as the alternating magnetic field by an alternating current.

  The second AC magnetic field applying means 10 is installed at a position upstream of the small diameter portion 11. The installation site may be either inside the tube 3 as shown in FIG. 1 or outside the tube 3.

  The diameter and length of the small-diameter portion 11 of the tube 3 are large enough to ensure a wider range than the dispersion width of the droplet 12 that is separated and dispersed in a granular state by applying an alternating magnetic field to the molten liquid 7 by the alternating magnetic field applying means 9. Therefore, it is desirable to make it as small as possible. Specifically, for example, when the flow rate of the molten liquid 7 discharged from the hole 5 is about 10 m / s and the diameter (inner diameter) of the tube 3 is about 1 m, the diameter (inner diameter) of the small diameter portion 11 is reduced to about 50cm and length should be about 1m.

  Next, a method for producing microparticles having a uniform size using the production apparatus 100 for carrying out the method for producing microparticles of the present invention as described above will be described.

  First, a silicon raw material, for example, is introduced into the container 4 as a raw material for the molten liquid 7 and heated by a heater 8 to melt the entire silicon to obtain a molten liquid 7. The upper part of the melted molten liquid 7 in the container 4 is pressurized with, for example, 0.7 MPa or less (preferably 0.01 MPa or more) with argon gas or the like, and a nozzle disposed at the bottom of the container 4 The molten liquid 7 is pushed out from the hole 5 of the member 6 and discharged into the tube 3. In addition, you may use the mechanical pressurization method for this pressurization method.

  Next, since the alternating magnetic field applying means 9 is arranged in the small diameter portion 11 of the tube 3, the alternating magnetic field applying means 9 arranged in a direction crossing the falling direction of the molten liquid 7 is dropped. When an AC voltage is applied, an AC magnetic field having the same period as the AC voltage is generated in the axial direction of the AC magnetic field applying means 9. Here, when the falling molten liquid 7 passes through the alternating magnetic field and is applied with the alternating magnetic field, the falling molten liquid 7 has conductivity, so that the falling molten liquid 7 is in the same direction as the alternating magnetic field. Periodic induced current is generated. The induced current and the alternating magnetic field applied by the alternating magnetic field applying means 9 cause a Lorentz force to act on the falling molten liquid 7.

  Due to the Lorentz force, the surface of the falling molten liquid 7 is deformed in a knot-like shape at regular intervals, and is separated into particles of a uniform size by the surface tension of the falling molten liquid 7. Will be divided. Since the hump-shaped deformation interval corresponds to half the period of the alternating magnetic field, the size of the droplet 12 to be divided is the diameter of the hole 5, the velocity of the molten liquid 7 falling, and the period of the alternating magnetic field. Determined by. Therefore, the frequency of the AC voltage applied to the AC magnetic field applying means 9 may be obtained from the diameter of the hole 5, the speed of the molten liquid 7 falling, and the desired droplet 12 size.

  At this time, the alternating magnetic field applying means 9 is arranged so that the falling molten liquid 7 passes across the central portion of the alternating magnetic field applying means 9, and the molten liquid 7 falling in the axial direction of the alternating magnetic field applying means 9 is used. It is desirable to arrange so as to be parallel to the direction of dropping. By arranging in this way, the molten liquid 7 passes through a portion where the alternating magnetic field by the alternating magnetic field applying means 9 is strong, and the directions of the induced current and the alternating magnetic field are orthogonal to each other. The Lorentz force can be effectively applied to 7 so as to be separated and dispersed in a granular form.

  In addition, since the flow velocity of the gas flowing into the pipe 3 from the gas inlet 1 and discharged from the gas outlet 2 increases at the small-diameter portion 11, the gas passes through the small-diameter portion 11 while being separated into particles. The liquid 7 passes through the small-diameter portion 11 while being accelerated in the direction of falling by the air current, and is prevented from coalescence and surely becomes a droplet 12 and falls downward.

  As described above, the molten liquid 7 that is falling is accelerated by an air flow in the small diameter portion 11 and separated into particles by applying an alternating magnetic field, whereby the Lorentz force generated by the alternating magnetic field by the alternating magnetic field applying means 9 is melted. The effect of separating and dispersing the liquid 7 in a granular form and the effect of accelerating the molten liquid 7 in the direction in which the air current whose flow velocity is increased in the small diameter portion 11 is separated into a granular form into a granular shape make the molten liquid 7 granular. The dropping trajectory of the droplets 12 generated after separation can be reliably changed and dispersed immediately after the separation, thus reliably preventing the coalescence of the droplets 12 having a uniform particle size immediately after the separation. Thus, fine particles having a uniform size can be produced.

  Then, the droplet 12 generated and dropped in the small diameter portion 11 is cooled and solidified during the dropping. For example, when silicon is used as the molten liquid 7, it is composed of granular single crystal silicon or a small number of crystal grains. It becomes granular polycrystalline silicon, and is collected and collected in a collection container 13 installed at the bottom of the tube 3.

  Here, when the second AC magnetic field applying means 10 for applying the second AC magnetic field is arranged above the small diameter portion 11 of the tube 3 in the direction crossing the falling molten liquid 7, the second AC is applied. By applying a second alternating magnetic field similar to the above-described alternating magnetic field by the alternating magnetic field applying means 9 to the falling molten liquid 7 by the magnetic field applying means 10, the falling molten liquid 7 above the small diameter portion 11 is applied. By applying the Lorentz force, the Lorentz force can cause the surface of the falling molten liquid 7 to have a knurled deformation at regular intervals, and the surface tension can separate the particles into a uniform size. In this case, the droplet 12 that has been separated into particles by the second alternating magnetic field applying means 10 and has reached the small diameter portion 11 is efficiently and reliably separated into particles by the alternating magnetic field applied by the alternating magnetic field applying means 9. And the droplets 12 can be more reliably prevented from coalescing.

  Further, by making the second AC magnetic field by the second AC magnetic field applying means 10 weaker than the AC magnetic field by the AC magnetic field applying means 9, the falling molten liquid 7 passing through the second AC magnetic field applying means 10 is reduced. By generating a hump-like deformation at regular intervals by Lorentz force on the surface, this is separated and dispersed individually by the alternating magnetic field by the alternating magnetic field applying means 9 while accelerating by the air flow in the small diameter portion 11, The generation of uniformly sized droplets 12 from the molten liquid 7 can also be performed more reliably and efficiently.

  In this way, also when the second AC magnetic field applying means 10 is used in addition to the AC magnetic field applying means 9, the liquid droplets 12 generated and dropped through the small diameter portion 11 are cooled and solidified while falling. For example, when silicon is used as the molten liquid 7, granular single-crystal silicon or granular polycrystalline silicon made up of a small number of crystal grains is stored in the recovery container 13 installed at the bottom of the tube 3 and recovered. Is done.

  As described above, according to the microparticle manufacturing apparatus 100 of the present invention and the microparticle manufacturing method of the present invention using the microparticle manufacturing apparatus 100 according to the present invention, it is possible to easily and surely use a device with a simple configuration that can be downsized. It is possible to efficiently produce fine particles having a uniform size.

  In addition, this invention is not limited to the example of the above embodiment, A various change may be added in the range which does not deviate from the summary of this invention. For example, instead of the second AC magnetic field applying means 10, a constant periodic disturbance may be given to the molten liquid 7 discharged from the hole 5 by directly giving a physical vibration having a constant period to the nozzle member 6. In this case, the molten liquid 7 can be reliably separated into droplets 12 having a desired uniform size at the small diameter portion 11, and fine particles having a uniform size can be stably generated. .

It is sectional drawing which shows schematic structure in an example of embodiment of the manufacturing apparatus for using the manufacturing method of the microparticles of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Gas inflow port 2 ... Gas outflow port 3 ... Pipe 4 ... Container 5 ... Hole 6 ... Nozzle member 7 ... Molten liquid 8 ... Heater 9 ... AC magnetic field application means
10 ... Second AC magnetic field applying means
11 ... Small diameter part
12 ... Droplet
13 ... Recovery container

Claims (6)

An alternating magnetic field that discharges the molten liquid from the hole and drops the inside of the pipe arranged in the vertical direction together with the air flow, and provides an alternating magnetic field in the direction across the molten liquid at the small diameter part provided in the middle of the pipe An application means is disposed, and the molten liquid falling is applied to the small-diameter portion while being accelerated by the air flow, applied to the alternating magnetic field while being separated into particles, and then solidified into fine particles. A method for producing fine particles. The method for producing fine particles according to claim 1, wherein the alternating magnetic field applying means is disposed above the small diameter portion. A second alternating magnetic field applying means for applying a second alternating magnetic field in a direction crossing the falling molten liquid is disposed above the small diameter portion, and the second alternating magnetic field is applied to the falling molten liquid. 3. The method for producing fine particles according to claim 1, wherein the fine particles are applied. A hole for discharging and dropping the molten liquid, a pipe disposed in the vertical direction with a small-diameter portion provided in the middle, allowing the discharged molten liquid to drop together with the air flow, and the small-diameter portion. And an alternating magnetic field applying means for applying an alternating magnetic field to the falling molten liquid in a direction crossing the falling direction. 5. The apparatus for producing microparticles according to claim 4, wherein the AC magnetic field applying means is disposed above the small diameter portion. 6. The fine particles according to claim 4, wherein a second alternating magnetic field applying means for applying a second alternating magnetic field in a direction crossing the molten liquid that is falling is disposed above the small diameter portion. Manufacturing equipment.

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