JP2005334865A - Solid particle classifier and solid particle classification method utilizing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid particle classifier with a simple structure capable of effectively classifying the huge amount of solid particles and a solid particle classification method utilizing the same. <P>SOLUTION: The solid particle classifier is used for classifying the solid particles in a suspension using a settling tank, and comprises a suspension supply means for continuously supplying the suspension to the settling tank, a pair of electrodes immersed in the tank and space apart from each other to constitute a suspension passage by a space formed by the spaced-apart electrodes, a direct current power source for applying a voltage to the electrodes and a supernatant portion recovery means for continuously recovering the supernatant portion of the suspension passing through the passage. The solid particle classification method employs the classifier to control the pH concentration of the suspension and performs the classification by regulating direct voltage in response to the zeta potential of the solid particle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sedimentation type solid particulate classifier, and more particularly to a solid particulate classification device that performs classification while applying a direct current voltage to a suspension flowing in a sedimentation tank, and a solid particulate classification method using the same.

  Techniques for classifying solid fine particle groups dispersed in a dispersion medium into predetermined particle groups include those using centrifugal force acting on solid fine particles, those using electrostatic force, and those using gravity. Further, in the classifying apparatus or method using these, a DC voltage or an alternating voltage is applied to the solid fine particles for those using a liquid or gas as a dispersion medium and those using an electrostatic force. There are various devices or methods.

  Among such solid fine particle classifiers or methods, a sedimentation type solid fine particle classifier utilizing gravity acting on solid fine particles using a liquid as a dispersion medium has a simple structure and can perform a large amount of classification treatment. Has the advantage of being able to. As such a solid fine particle classifier, for example, in Patent Document 1, a treatment liquid containing solid particles is supplied into a stationary tank, and among the solid particles in the treatment liquid, solid particles having a high terminal velocity are directed toward the bottom surface. In a floating sedimentation type separation device that takes out from the lower discharge port provided in the center of the bottom surface, raises the solid particles having a low terminal velocity, and takes out from the upper discharge port, supply the processing liquid into the stationary tank. There has been proposed a sedimentation type solid fine particle classifier that is configured to perform from a plurality of supply nozzles uniformly distributed in the same horizontal section of a stationary tank.

  On the other hand, an electrostatic classification type solid fine particle classification apparatus or method that uses electrostatic force acting on solid fine particles by applying a DC voltage using a liquid as a dispersion medium is a method in which the potential and charge of the solid fine particles themselves and the voltage to be applied This has the advantage of being able to classify with high accuracy by utilizing the action and effect of. As such a solid fine particle classification method, Patent Document 2 discloses that a dispersion liquid in which a fine particle material is dispersed in a dispersion medium is filled in a water tank, a cathode and an anode are disposed in the water tank, and a DC voltage is applied between the electrodes. There has been proposed a classification method in which large particle diameter particles are selectively adhered on an electrode plate from dispersed particles made of a fine particle material by applying an electric field generated between the electrodes, and the large particle diameter particles are removed.

  Patent Document 3 discloses a flow path through which a solution containing particles can flow, and a deflecting unit that deflects the particles by generating an electric field or a magnetic field in a direction crossing the flow path in a predetermined region of the flow path. There has been proposed a particle separation mechanism provided with a particle trapping part that is arranged on the deflection side where the particles are attracted by the deflection means in the flow path and can capture the particles.

JP 2003-24819 A JP-A-5-40084 JP 2002-233792 JP

  However, such a conventional sedimentation classification type solid fine particle classification apparatus or method has a problem that the classification accuracy is generally poor. On the other hand, an electrostatic classification type solid fine particle classification apparatus or method is generally not suitable for classifying a large amount of solid fine particles. In addition, the solid fine particle classification method proposed in Patent Document 2 is a plurality of times in advance in order to prevent coarse particles from being mixed into a product due to the phenomenon that solid fine particles having a larger particle size are more easily moved in the dispersion medium. There is a problem that coarse grains must be removed. The solid fine particle classification mechanism proposed in Patent Document 3 has a problem that a particle trapping part having a special structure must be provided.

  The present invention has been made in view of such conventional problems, and is capable of effectively classifying a large amount of solid fine particles with a simple structure, and a solid fine particle classification method using the same. The purpose is to provide.

  The inventors of the present invention combine a sedimentation classification technique that performs classification by flowing a suspension in which solid fine particles are dispersed in a sedimentation tank, and an electrostatic classification technique that performs classification while applying a DC voltage. Therefore, the present invention has been completed by obtaining the knowledge that gravity, electrostatic force and water flow acting on the solid fine particles can be used, and that the solid fine particles in the suspension can be classified in large quantities with high accuracy. It was. In the following description, the term “upper or lower” used in relation to the direction or position means that it is above or below the direction of gravity.

  The solid fine particle classifying device according to the present invention is a solid fine particle classifying device for classifying solid fine particles in a suspension using a sedimentation tank as shown in claim 1, and the suspension is continuously provided in the sedimentation tank. Suspension supply means for supplying, a pair of electrodes immersed in the settling tank and spaced apart from each other as a flow path for the suspension, a direct current power source for applying a voltage to the pair of electrodes, and the flow And a supernatant recovery means for recovering a supernatant portion of the suspension that has passed through the passage. In the solid fine particle classifier, as shown in claim 2, it is preferable to further provide a concentrating part recovery means for recovering a concentrated part of the suspension.

  Further, in the solid fine particle classifier, the suspension supply means for continuously supplying the suspension to the sedimentation tank is, as shown in claim 3, stirring the dispersion medium and the solid fine particles to produce a suspension. A tank, an ultrasonic dispersion device for irradiating the suspension with ultrasonic waves to disperse the solid fine particles, a pump for continuously supplying the suspension irradiated with the ultrasonic waves to the settling tank through a suspension supply pipe, and Preferably, the suspension supply pipe has a distribution pipe that has a large number of suspension supply ports at its end and protrudes into the settling tank, as shown in claim 4. preferable.

  Further, the suspension supply port side portion into which the suspension of the solid fine particle classifier flows into the sedimentation tank is as shown in claim 5, and the inlet side portion of the sedimentation tank is the suspension that has flowed into the sedimentation tank. It is preferable that the liquid is formed so as to gradually expand the flow path in the direction of the flow, and as shown in claim 6, the upper part of the suspension supply port where the suspension supply pipe opens into the settling tank Alternatively, it is preferable that a clean water supply port for supplying clean water to the upper and lower portions is provided. Furthermore, as shown in claim 7, it is preferable that a separator projecting in the direction in which the suspension flows from the sedimentation tank is provided between the turbid liquid supply port and the clean water supply port.

  In the solid particulate classifier, the supernatant recovery means for recovering the supernatant part of the suspension communicates with an upper discharge port provided at the upper part of the outlet side part of the settling tank, as shown in claim 8. It is preferable to have an upper discharge pipe and a flow meter. As shown in claim 9, the concentrating part recovery means for recovering the concentrated part of the suspension is provided at the outlet side part of the sedimentation tank and provided at the lower part of the upper outlet, and the lower part communicating with the lower part. It preferably has a discharge pipe and a flow meter.

  Further, as shown in claim 10, the discharge side portion of the settling tank that discharges the suspension that has passed through the flow path between the pair of electrodes in the settling tank is between the upper discharge port and the lower discharge port. Preferably, a guide member is provided for guiding the supernatant portion and the concentrated portion of the suspension to the upper discharge port and the lower discharge port, respectively. As shown in claim 11, a porous plate is provided in front of the upper discharge port of the settling tank. It is preferred that

  Furthermore, as shown in claim 12, the sedimentation tank is preferably provided so as to incline toward the direction in which the suspension flows, and as shown in claim 13, the bottom of the sedimentation tank, or a pair of It is preferable that a discharge device for discharging the slurry deposited on the upper part of the lower electrode among the electrodes is provided.

  In the solid fine particle classifier, the pair of electrodes provided by being immersed in the settling tank is preferably made of a porous metal plate as shown in claim 14, and the pair of electrodes is shown in claim 15. It is preferable that a change-over switch capable of switching the polarity of the voltage applied to is provided.

  Further, as shown in claim 16, it is preferable that a filter is provided on the upper surface of the electrodes disposed below the pair of electrodes, and as shown in claim 17, gas generated from the pair of electrodes It is preferable that a collection / deaeration device is provided.

  Further, the solid fine particle classifier is preferably provided with a liquid circulation device for collecting and refluxing the supernatant liquid overflowing the supernatant portion of the suspension, as shown in claim 18.

  The solid fine particle classification method according to the present invention is a method for performing classification after adjusting the pH concentration of a suspension, as shown in claim 19. Furthermore, according to the twentieth aspect of the invention, the classification is performed by adjusting the voltage applied to the pair of electrodes in accordance with the zeta potential of the solid fine particles in the suspension when classifying the solid fine particles.

  According to the solid fine particle classifying apparatus according to the present invention, a large amount of solid fine particles can be classified with high accuracy with a simple structure. Moreover, according to the solid fine particle classification method of the present invention, the solid fine particles can be classified efficiently.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a solid fine particle classifying apparatus according to an embodiment of the present invention. In this example, the solid fine particle classifier includes a settling tank 11, suspension supplying means 30 for continuously supplying the suspension 65 to the settling tank 11, and the separated space immersed in the settling tank. A pair of electrodes 21 and 22 as a flow path 60 of the liquid 65, a DC power source 25 that applies a voltage to the pair of electrodes 21 and 22, a supernatant portion recovery that recovers a supernatant portion of the suspension 65 that has passed through the flow path 60 Means 14.

  The settling tank 11 can fill the suspension 65, and includes an inlet side portion into which the suspension 65 flows, an outlet side portion from which the suspension 65 is discharged, and a pair disposed inside the settling tank 11. As long as the electrodes 21 and 22 are provided, the shape and form are not limited. In the example of FIG. 1, the shape and form of a horizontal floor type having a rectangular cross section is shown. However, as shown in FIG. 2, the settling tank 11 has a cylindrical and vertical form and form. Also good. In the example of FIG. 2, a cylindrical settling tank 11 has a pair of electrodes including an outer cylinder electrode 211 and an inner cylinder electrode 221. That is, the optimum shape and form of the sedimentation tank 11 are selected in consideration of the characteristics of solid fine particles to be classified, the processing amount, and the like.

  A suspension supply port 121 is provided at the inlet side portion of the settling tank 11, and the suspension supply port 121 communicates with the suspension supply pipe 12. The settling tank 11 is provided with a clean water supply port 131 (a lower clean water supply port 131A and an upper clean water supply port 131B) so as to sandwich the suspension supply port 121, and a clean water supply pipe 13 The clean water supply pipe 13A communicates with the upper clean water supply pipe 13B). By supplying clean water from the lower clean water supply port 131A to the settling tank 11, as described below, it is possible to prevent the accumulation of fine particles on the bottom of the settling tank 11, and from the upper clean water supply port 131B. By supplying clean water to the settling tank 11, it is possible to prevent coarse particles from being mixed into the supernatant of the suspension 65. It should be noted that optimum values are adopted for the opening area of the lower clean water supply port 131A and the upper clean water supply port 131B, the installation position from the bottom of the settling tank 11, etc., depending on the characteristics of the solid fine particles to be processed, the processing amount, and the like.

  Further, the inlet side portion of the sedimentation tank 11 is suspended between the lower clean water supply port 131A and the suspension supply port 121, and between the suspension supply port 121 and the upper clean water supply port 131B. Separating plates 16 (a lower separating plate 16A and an upper separating plate 16B) protruding from the wall portion of the settling tank 11 are provided in the direction in which the liquid 65 flows. Thereby, the flow of the suspension 65 and the clean water easily becomes a laminar flow state. In addition, it is preferable that the separating plate 16 can change the attachment angle to the settling tank 11.

  On the other hand, at the outlet side portion of the sedimentation tank 11 that follows the space sandwiched between the pair of electrodes 21 and 22 of the sedimentation tank 11, the supernatant portion of the classified suspension 65 (the portion that is recovered as a normal product is a predetermined portion). Supernatant portion collecting means 14 is provided for discharging and collecting fine particles having a particle size equal to or smaller than the average particle diameter of particles and the fine particles) from the sedimentation tank 11. That is, the supernatant recovery means 14 has an upper discharge port 142, an upper discharge pipe 141 and a flow meter (not shown) provided at the upper part of the outlet side portion of the settling tank 11, and the suspension 65 The supernatant portion is continuously discharged and collected through the upper discharge port 142, the upper discharge pipe 141 and the flow meter.

  Further, in the example of FIG. 1, the concentrated portion of the suspension 65 (usually a portion that is discarded and includes coarse and coarse particles that exceed the target average particle size) is recovered at the bottom of the upper discharge port 142. Means are provided. That is, a concentration unit recovery means 15 having a lower discharge port 152, a lower discharge tube 151 and a flow meter (not shown) provided at the lower part of the upper discharge port 142 is provided, and the suspension 65 The concentrated portion is continuously discharged and collected through the discharge port 152, the lower discharge pipe 151 and the flow meter. Thereby, classification can be performed continuously. In addition, classification accuracy can be improved. The height position of the upper discharge port 142 and the lower discharge port 152 from the bottom surface of the sedimentation tank 11, the opening area, etc. are optimal depending on the properties of the solid fine particles, the classification range, the amount of suspension to be processed, etc. Adopted.

  Further, as shown in FIG. 1, the supernatant portion and the concentrated portion of the suspension 65 are placed between the upper discharge port 142 and the lower discharge port 152 at the outlet side portion of the settling tank 11, respectively. A guide member 17 that leads to the discharge port 152 is provided so as to extend from the wall surface of the settling tank 11 in the upstream direction of the flow path 60. Thereby, the classification accuracy can be improved.

  In such a sedimentation tank 11, suspension supply means 30 for continuously supplying the suspension 65 is provided. As shown in FIG. 1, the suspension supply means 30 is a solid tank by irradiating the suspension 65 with ultrasonic waves, stirring the dispersion medium 67 and the solid fine particles 66 to generate the suspension 65. An ultrasonic dispersion device 37 that disperses the fine particles 66, a pump 33 that continuously supplies the suspension 65 irradiated with ultrasonic waves to the sedimentation tank 11 through the suspension supply pipe 12, and a flow rate adjustment device 35 are provided. The suspension supply means 30 supplies a predetermined suspension 65 to the sedimentation tank 11 through the suspension supply pipe 12 and the suspension supply port 121.

  The stirring tank 31 is used to mix and disperse the raw material slurry composed of the dispersion medium 67 and the solid fine particles 66, and the ultrasonic dispersion device 37 is used to uniformly disperse the solid fine particles 66. The ultrasonic dispersion device 37 is provided in the middle of the suspension supply pipe 12 in the example of FIG. 1, but is preferably provided at the inlet of the stirring tank 11. The pump 33 is used to supply the raw material slurry in which the solid fine particles 66 are uniformly dispersed to the settling tank 11, and the supply amount of the supplied raw material slurry is kept constant by the flow rate adjusting device 35.

  In the example of FIG. 1, the following clean water supply means 40 is further attached to the suspension supply means 30. That is, a clean water supply means 40 having a water tank 41 filled with clean water, a pump 43, and a flow rate adjusting device 45 is attached, and the clean water supply pipe 13 (the bottom clean water supply pipe 13A, the bottom clean water A predetermined amount of clean water is supplied from the lower and upper portions of the suspension supply port 121 through the water supply pipe 13B) and the clean water supply port 131 (the lower clean water supply port 131A and the upper clean water supply port 131B). ing. Thereby, the classification accuracy can be improved as described below.

  As the water tank 41, the pump 43, and the flow rate adjusting device 45, known ones can be used. The flow rate adjusting device 45 can independently control the flow rates of clean water flowing from the lower clean water supply port 131A and the upper clean water supply port 131B. The clean water can be supplied only from the lower part of the suspension supply port 121, or can be prevented from being supplied at all. The optimum one is selected according to the classification accuracy required for the product, the throughput of the suspension to be treated, and the like.

  As shown in FIG. 1, the pair of electrodes provided in the present solid fine particle classifier includes a plate-like electrode 21 provided at the top of the settling tank 11 and a plate-like electrode 22 provided at the bottom. The pair of electrodes 21 and 22 is provided with a DC power source 25 capable of applying a DC voltage. The space portion sandwiched between the electrode 21 and the electrode 22 is a suspension 65 flowing from the suspension supply port 121, and a flow path 60 through which clean water flowing from the clean water supply ports 131A and 131B flows, The mixed water of the suspension 65 and clean water passes through the flow path 60 and is discharged from the upper discharge port 142 and the lower discharge port 152.

  The shape of the pair of electrodes 21 and 22 is not necessarily flat. For example, as shown in FIG. 2, a cylindrical outer cylinder electrode 211 and an inner cylinder electrode 221 may be used. The pair of electrodes 21 and 22 can be formed of a copper, aluminum plate, a mesh material, a porous plate, or the like.

  The present invention is based on the sedimentation classification technique as described above, and is composed of a technique in which the electrostatic classification technique for performing classification while applying a DC voltage is combined. That is, in the classification of the present invention, the suspension 65 is continuously flowed to the sedimentation tank 11 provided with the pair of electrodes 21 and 22, and is usually recovered from the supernatant part as a normal product and the lower part of the sedimentation tank 11. This is done by continuously fractionating the concentrated part to be discarded. Specifically, the solid fine particles are classified using the solid fine particle classifier as described below.

  First, in order to prepare the suspension 65 corresponding to the target product, the optimum pH concentration of the suspension is examined in advance. FIG. 3 is a graph showing the relationship between the pH concentration of the suspension 65 and the zeta potential of the silica particles in the suspension 65 when classifying the silica particles. According to FIG. 3, when the pH concentration is changed from 7.0 to 7.5, the zeta potential changes rapidly from -36 mV to -51 mV, and then the zeta potential gradually decreases (minus side) as the pH concentration shifts to the alkali side. Further, it can be seen that the zeta potential hardly changes in the pH concentration range of 8.0 to 9.5 and is stable. That is, it can be seen that the silica fine particles can be classified effectively by using a suspension 65 having a pH of 8.0 to 9.5 and applying a DC voltage thereto. The silica fine particles used were those manufactured by Denki Kagaku Kogyo Co., Ltd. The average particle size was 4.1 μm. The average particle size was measured by a laser diffraction method using a particle size distribution analyzer LA920 manufactured by Horiba. The zeta potential was measured with a Zetasizer 2000 from Malvern Instruments Ltd. The pH concentration of the suspension 65 was adjusted by adding sodium hydroxide using a suspension having a pH concentration of 7.

Further, in classifying the solid fine particles, it is preferable to measure the zeta potential of the solid fine particles in advance before and after the average particle diameter of the target product and apply a DC voltage corresponding to the zeta potential to the suspension 65. . FIG. 4 shows an example in which acrylic resin fine particles are classified. The average particle diameter and zeta potential of acrylic resin fine particles when acrylic resin fine particles having an average particle diameter of 2.4 to 5.2 are dispersed in a pure water dispersion medium. It is a graph which shows the relationship. According to FIG. 4, it can be seen that the zeta potential is proportional to the average particle size. That is, it can be seen that efficient classification can be performed by adjusting the DC voltage applied to the suspension according to the particle size of the product. The acrylic resin particles used were those manufactured by Hayakawa Rubber Co., Ltd. The dispersion medium is pure water,
The pH concentration of the suspension was 7. Measurement of the average particle diameter, measurement of the zeta potential, and adjustment of the pH concentration of the suspension 65 were performed in the same manner as in FIG.

  Next, based on the above result, a predetermined suspension 65 is prepared and continuously supplied to the sedimentation tank 11. That is, the solid fine particles 66 and the dispersion medium 67 are stirred in the stirring tank 31 and irradiated with ultrasonic waves by the ultrasonic dispersion device 37 to generate a suspension 65 in which the solid fine particles 66 are uniformly dispersed in the dispersion medium 67. Then, the suspension 65 is continuously supplied to the sedimentation tank 11 through the suspension supply pipe 12 by the pump 33 and the flow rate adjusting device 35. At the same time, from a portion (not shown) communicating with the suspension supply pipe 12, for example, sodium hydroxide is added to adjust the pH concentration of the suspension 65. At the same time, the clean water supply means 40 supplies clean water to the sedimentation tank 11 from the lower clean water supply port 131A and the upper clean water supply port 131B. The suspension 65 and clean water are preferably supplied to the settling tank in a laminar flow state. For this reason, the flow rates of the suspension 65 and the clean water are adjusted so as to be in a laminar flow state.

  In the present invention, as described above, laminar clean water flows above and below the laminar suspension 65 on the inlet side of the settling tank 11. For this reason, the flow of the clean water flowing under the layer of the suspension 65 can prevent the particles from falling in the suspension 65 and prevent the particles from being mixed into the concentrated portion of the suspension 65. . Furthermore, the flow of clean water flowing above the layer of the suspension 65 can prevent the coarse particles from rising in the suspension 65 and prevent the coarse particles from being mixed into the product. Thereby, a high quality product with high classification accuracy can be produced with a high recovery rate. As described above, in this example, the clean water is supplied from above and below the suspension supply port 121. However, there is a problem that coarse particles are mixed into the product depending on the properties of the solid fine particles. If this is not the case, clean water can be supplied only to the lower side of the suspension supply port 121.

  Next, the magnitude of the DC voltage applied to the pair of electrodes 21 and 22 is determined in consideration of the zeta potential of the solid fine particles 66 as described above. The polarity of the DC voltage applied to the pair of electrodes 21 and 22 is such that, for example, those having a negative zeta potential such as silica fine particles or acrylic resin fine particles shown in FIGS. The electrode 22 is preferably a positive electrode. However, in order to increase the product recovery amount, the electrode 21 may be a positive electrode and the electrode 22 may be a negative electrode. Therefore, the polarity of the DC voltage applied to the pair of electrodes 21 and 22 is selected in consideration of the electrical characteristics, production efficiency, etc. of the solid fine particles 66, so that the DC power source 25 can be easily changed in polarity. It is preferable to provide a changeover switch for switching the polarity.

  The suspension 65 that has passed through the flow path 60 sandwiched between the pair of electrodes 21 and 22 has coarse particles in the concentrated portion deposited on the bottom of the sedimentation tank 11, and a solid having a relatively large average particle size. A portion containing fine particles (coarse particles) is continuously discharged from the lower discharge port 152. As a result, fine particles as a product are continuously recovered from the supernatant of the suspension 65 recovered from the upper discharge port 142 at the top of the settling tank.

  In recovering the supernatant part of the suspension, the solid particulate classifier introduces the supernatant part between the upper outlet 142 and the lower outlet 152 to the upper outlet 142 as described above, and the concentrated part. A guiding member 17 is provided to facilitate guiding to the lower discharge port 152. As a result, the supernatant portion of the suspension containing more target particles can be recovered, and mixing into the supernatant portion of the concentrated portion containing unnecessary particles can be prevented, and the concentrated portion can be quickly discharged.

  Such a guide member 17 may be any member as long as it has the above-described function, and the shape, the attachment position to the sedimentation tank 11 and the like are selected optimal for the solid fine particle classifier. As shown in FIG. 1, not only the guide member 17 extending in the horizontal direction from the wall surface of the settling tank 11 but also a guide member 17 having an elevation angle or a dip angle can be used. In addition, it is possible to use the guide member 17 that vibrates up and down with the wall surface attachment portion of the settling tank 11 as a fulcrum. Further, as shown in FIG. 1, a bent portion 171 can be provided at the distal end portion of the guide member 17, and an arcuate guide member 17 can also be used.

  Further, in order to discharge the concentrated portion of the suspension 65 more quickly, the sedimentation tank 11 is provided so as to be inclined downward in the direction in which the suspension 65 flows, as shown by a one-dot chain line in FIG. Is good. Depending on the characteristics of the solid fine particles 66 and the magnitude and polarity of the DC voltage applied to the suspension 65, the settling tank 11 may be provided so as to be inclined upward in the direction in which the suspension 65 flows. In some cases, the inclination angle θ of the settling tank 11 is selected to be an optimal value in the range of −90 ° <θ <90 °.

  As described above, by classifying solid fine particles using the above-mentioned solid fine particle classifier, there is no mixing of coarse particles (including coarse particles), and the quality is good, and the product contains more targeted fine particles. Can be obtained. However, the solid fine particle classifier according to the present invention is not limited to the above-described embodiments. For example, as shown in FIG. 2, a distribution pipe 125 having a large number of suspension supply ports 126 at the end of the suspension supply pipe 12 may be provided so as to protrude from the wall surface of the settling tank 11 to the inside. . In addition, as shown in FIG. 5, it is preferable that the suspension 65 flowing into the settling tank 11 is formed so as to gradually expand the flow path 60 in the direction of the flow. As a result, the suspension 65 and clean water can be supplied in a more laminar state. 2 and 5 indicate the direction in which the suspension 65 flows.

  As shown in FIG. 6, a guide member 161 can be provided in front of the suspension supply port 121 such that the suspension 65 flowing into the sedimentation tank 11 faces the bottom of the sedimentation tank 11. Thereby, mixing of the coarse grain to a product can be prevented.

  In addition, as shown in FIG. 7, the wall portion between the upper discharge port 142 and the lower discharge port 152 of the settling tank 11 is a curved wall 172 so that the effect of the guide member 17 provided on the outlet side of the settling tank 11 is achieved. Can be demonstrated. Further, as shown in FIG. 7, a porous plate 175 can be provided in front of the upper discharge port 142 of the settling tank 11.

  Further, as shown in FIG. 7, the supernatant can be separated and recovered from the supernatant of the suspension so that it can be reused. That is, in the solid particulate classifier having the suspension supply means 30 in the sedimentation tank 11 in which the pair of electrodes 21 and 22 are disposed, the supernatant liquid overflows into the region where the supernatant portion of the suspension 65 is discharged. By providing the weir 176 to be mixed and mixing the suspension liquid into the suspension supply pipe 12 via the circulation circuit 73 and the pump 75 for circulating the supernatant liquid, it is possible to provide the liquid circulation device 70 capable of reusing the supernatant liquid. Instead of the above weir 176, the wall 173 of the settling tank 11 can be shaped so that the supernatant liquid can overflow as shown in FIG.

  Further, a filter 18 can be provided on the upper surface of the electrode 22 disposed below the pair of electrodes 21 and 22, as shown in FIG. Thereby, discharge of the slurry containing coarse particles or coarse particles deposited on the bottom of the sedimentation tank can be easily performed. For example, it is possible to provide a discharge device 19 that recovers the slurry accumulated on the filter 18 from the recovery pipe 192 provided on the opposite side of the bottom of the settling tank 11 by the water flow from the cleaning water pipe 191 provided on the bottom side of the settling tank 11. it can. The material of the filter 18 may be any material such as cloth, synthetic paper, or felt.

  Further, during operation of the solid particulate classifier, gas is generated from the vicinity of the pair of electrodes 21 and 22, and therefore a collection / deaeration device 50 for collecting and degassing this gas can be provided. That is, in the example shown in FIG. 10, the gas generated from the vicinity of the electrode 21 is collected in the deaeration tank 52 together with the suspension 65 through the pipe 53 by the pump 51, degassed inside the deaeration tank 52 and externally Are discharged and collected. On the other hand, the gas generated from the vicinity of the electrode 22 is collected in the deaeration tank 56 together with the suspension 65 through the pipe 57 by the pump 55, degassed inside the deaeration tank 56, and discharged and collected outside. It has become.

  The degassing / recovery of the gas generated from the vicinity of the electrode 22 reduces the classification accuracy due to the stirring effect of the suspension 65 by the gas, the prevention of settling of the solid fine particles, and the winding of coarse particles accumulated at the bottom of the settling tank 11. This is preferable because it can be prevented. The electrode 22 is preferably made of a mesh member or a porous plate so that the gas does not grow into large bubbles. The opening size of the mesh member or the perforated plate is preferably about several mm to 1 cm.

  A classification test was performed using the solid fine particle classifier shown in FIG. The sedimentation tank 11 of the solid fine particle classifier had a width of 22 cm, a height of 4 cm, and a length of 140 cm. The pair of electrodes 21 and 22 used was a 1 mm copper wire formed from a wire mesh having a 10 mm square opening. The solid fine particle group as a raw material was prepared by mixing acrylic resin particles having an average particle diameter of 5 μm and 8 μm at a mass ratio of 1: 1. The particle size distribution of this raw material powder is shown in FIG. The raw material powder was dispersed in pure water to prepare a suspension 65. The suspension 65 was continuously supplied at a flow rate of 0.3 liter / min. After 60 minutes from the operation of the solid fine particle classifier, the particle size distribution of the acrylic resin particles present in the supernatant portion (product) recovered from the upper outlet 142 was measured. The average particle diameter of the acrylic resin particles was measured with a particle size distribution measuring instrument LA920 manufactured by Horiba, Ltd. as in the case of FIG. 3, and the particle size distribution was measured by a Coulter counter method. This test was performed without supplying clean water to the sedimentation tank 11.

  FIG. 12 is a graph showing the particle size distribution of the product when a DC voltage of 100 V is applied to the pair of electrodes 21 and 22, and FIG. 13 is a graph when the DC voltage is not applied to the pair of electrodes 21 and 22. According to FIG. 12, it can be seen that the number of acrylic resin particles having an average particle diameter of 8 μm is reduced and classification is progressing. On the other hand, in the case of FIG. 13, it can be seen that a considerable amount of acrylic resin particles having an average particle diameter of 8 μm remain, and the classification is not so advanced.

  A pair of electrodes 21 and 22 were made of a copper punching metal having an aperture ratio of 20%, and the voltage applied thereto was set to 50 V and 100 V. The classification test was performed in the same manner as in Example 1 except for other conditions. FIG. 14 shows the particle size distribution of the raw material powder. FIG. 15 shows the particle size distribution of the product when a DC voltage of 50 V is applied, and FIG. 16 is a graph showing the particle size distribution of the product when a DC voltage of 100 V is applied. According to FIG. 15, the number of acrylic resin particles having an average particle diameter of 8 μm is very small, and the classification proceeds, and according to FIG. 16, it can be seen that the classification is good without the presence of acrylic resin particles having an average particle diameter of 8 μm. .

  According to the above test results, it can be seen that the magnitude of the voltage applied to the pair of electrodes 21 and 22 and the shape of the electrodes 21 and 22 are closely related to the classification accuracy. 13 and 16, when the punching metal is used for the pair of electrodes 21 and 22, classification is more advanced than the case of FIG. 13 using the wire mesh. This is because the total electrode area is larger than that of the metal mesh, and the punching metal has a structure in which fine bubbles are retained in the electrode portion and less likely to grow into larger bubbles than the metal mesh. It is presumed that The current flowing between both electrodes when a DC voltage of 100 V was applied was about 48 mA, but in any case, it was confirmed that bubbles were generated near both electrodes 21 and 22 (bubbling). could not.

A classification test was performed using a suspension 65 in which silica fine particles were dispersed in pure water. In this example, classification was performed by supplying clean water below and above the suspension. The inflow rate of the suspension from the suspension supply port 121 to the settling tank 11 and the inflow rate of the clean water from the lower clean water supply port 131A and the upper clean water supply port 131B to the settling tank 11 are both 9.56 × 10 ^{− 4} m / s. FIG. 17 shows the particle size distribution of the silica fine particle raw material powder and the particle size distribution of the fine particles (product) recovered from the upper outlet 142 when classification is performed with the applied DC voltage being 0 V, 5 V and 10 V. It is a graph to show. According to FIG. 17, it can be seen that good classification is performed by application of a DC voltage, particularly by application of 10V. The particle size distribution was measured in the same manner as in Example 1. The pair of electrodes 21 and 22 were made of stainless steel plate.

It is a schematic diagram which shows the solid fine particle classification device which concerns on this invention. It is the schematic diagram of the other Example from which the form of a sedimentation tank, a pair of electrode, and a suspension supply pipe | tube differs from the case of FIG. 6 is a graph showing the relationship between the pH concentration of a suspension and the zeta potential of silica fine particles when silica fine particles are dispersed in pure water. It is a graph which shows the relationship between the average particle diameter of an acrylic resin particle, and a zeta potential at the time of disperse | distributing the fine particle of an acrylic resin in a pure water. It is a schematic diagram of the other Example from which the shape of the entrance side of a sedimentation tank differs. It is a schematic diagram of the example which provided the guidance member in the entrance side of a sedimentation tank. It is a schematic diagram which shows the Example which provides a perforated plate in the front surface of the upper discharge port of a sedimentation tank, and also makes the supernatant liquid of a supernatant part reusable. It is sectional drawing of the XX part of FIG. It is a schematic diagram of the Example in which the filter was provided in the upper surface of the electrode arrange | positioned under a pair of electrode, and also the discharge apparatus which discharges | emits the slurry deposited on the filter upper part was provided. It is a schematic diagram of the Example provided with the collection / deaeration apparatus of the gas emitted from the vicinity of a pair of electrode. 3 is a graph showing the particle size distribution of raw material powder used in the test of Example 1. FIG. It is a graph which shows the test result of Example 1 when the direct current voltage applied to a pair of electrodes is 100V using the electrode made from a metal mesh. It is a graph which shows the test result of Example 1 at the time of using a wire-mesh electrode and not applying a DC voltage to a pair of electrodes. 3 is a graph showing the particle size distribution of raw material powder used in the test of Example 2. FIG. It is a graph which shows the test result of Example 2 when the direct voltage applied to a pair of electrodes is set to 50V using the electrode made from a punching metal. It is a graph which shows the test result of Example 2 when the direct voltage applied to a pair of electrodes is 100V using the electrode made from a punching metal. It is a graph which shows the test result of Example 3 which performed classification by supplying clean water under and the upper part of suspension.

Explanation of symbols

11 Settling tank
12 Suspension supply pipe
121 Suspension supply port
125 minutes piping
126 Multiple suspension supply ports
13 Clean water supply pipe
13A clean water supply pipe
13B Clean water supply pipe
131 Clean water supply port
131A Purified water supply port
131B Clean water supply port
14 Supernatant recovery means
141 Top discharge pipe
142 Upper outlet
15 Concentrator recovery means
151 Bottom discharge pipe
152 Bottom outlet
16 Separator
16A Bottom separator
16B upper separator
161 Guide member
17 Guide member
171 Bending part
172 Curved wall
173 Wall
175 perforated plate
176 weir
18 Filter
19 Discharge device
191 Cleaning water pipe
192 Recovery tube
21 electrodes
22 electrodes
211 outer cylinder electrode
221 Inner cylinder electrode
25 DC power supply
30 Suspension supply means
31 Mixing tank
33 Pump
35 Flow controller
37 Ultrasonic disperser
40 Clean water supply means
41 water tank
43 Pump
45 Flow controller
50 Collection and deaeration equipment
51 pump
52 Deaeration tank
53 Piping
55 Pump
56 Deaeration tank
57 Piping
60 channels
65 Suspension
66 Solid particles
67 Dispersion media
70 Liquid circulation device
73 Circulation circuit
75 pump

Claims (20)

  A solid fine particle classification device for classifying solid fine particles in a suspension using a settling tank, the suspension supply means for continuously supplying the suspension to the settling tank, and the two separated from each other immersed in the settling tank A pair of electrodes having the separation space as a flow path for the suspension, a direct current power source for applying a voltage to the pair of electrodes, and a supernatant portion for continuously collecting a supernatant portion of the suspension that has passed through the flow path A solid fine particle classification device comprising a recovery means.   2. The solid fine particle classifier according to claim 1, further comprising a concentration part collecting means for continuously collecting a concentrated part of the suspension.   3. The solid particle classification apparatus according to claim 1, wherein the suspension supply means for continuously supplying the suspension to the settling tank is a stirring tank for stirring the dispersion medium and the solid particles to generate a suspension. An ultrasonic dispersion device for irradiating a suspension with ultrasonic waves to disperse the solid fine particles, a pump for continuously supplying the suspension irradiated with the ultrasonic waves to the settling tank through a suspension supply pipe, and a flow rate adjusting device Solid particle classifier characterized by comprising the following.   The solid fine particle classification apparatus according to any one of claims 1 to 3, wherein the suspension supply pipe has a distribution pipe protruding into a sedimentation tank having a large number of suspension supply ports at its end. Solid fine particle classifier.   5. The solid fine particle classification device according to claim 1, wherein the inlet side portion into which the suspension of the sedimentation tank flows is configured so that the suspension that has flowed into the sedimentation tank gradually moves the flow path in the direction of the flow. A solid fine particle classifying device formed so as to expand.   6. The solid fine particle classification apparatus according to claim 1, wherein the suspension supply pipe supplies clean water to an upper portion of the suspension supply port that opens to the settling tank, or to an upper portion and a lower portion. A solid fine particle classifier.   In the solid particulate classification device according to any one of claims 1 to 6, a separator projecting in a direction in which the suspension flows from the settling tank is provided between the suspension supply port and the clean water supply port. A solid fine particle classifier.   The solid particulate classifier according to any one of claims 1 to 7, wherein the supernatant recovery means for recovering the supernatant portion of the suspension is an upper discharge port provided at an upper portion of the outlet side portion of the settling tank, A solid fine particle classifier having an upper discharge pipe and a flow meter communicating with each other.   The solid particulate classifier according to any one of claims 1 to 8, wherein the concentration part recovery means for recovering the concentrated part of the suspension is provided at the outlet side part of the settling tank and at the lower part of the upper discharge port. A solid fine particle classifier comprising a lower discharge port, a lower discharge pipe communicating with the lower discharge port, and a flow meter.   The solid particulate classifier according to any one of claims 1 to 9, wherein the sedimentation tank includes a supernatant portion and a concentrated portion of the suspension between an upper outlet and a lower outlet, respectively, an upper outlet and a lower outlet. A solid fine particle classifying device, characterized in that a guiding member is provided for guiding to a solid.   The solid particle classification device according to any one of claims 1 to 10, wherein a porous plate is provided in front of the upper discharge port of the sedimentation tank.   The solid particulate classifier according to any one of claims 1 to 11, wherein the sedimentation tank is provided so as to incline toward a direction in which the suspension flows.   The solid particle classification device according to any one of claims 1 to 12, wherein a discharge device for discharging slurry deposited on a bottom portion of a sedimentation tank or an upper portion of a lower electrode of a pair of electrodes is provided. Solid fine particle classifier.   14. The solid fine particle classifying apparatus according to claim 1, wherein the pair of electrodes are made of a porous metal plate.   15. The solid particulate classifier according to claim 1, wherein the DC power source is provided with a changeover switch for switching the polarity of the voltage applied to the pair of electrodes.   16. The solid particle classification device according to claim 1, wherein a filter is provided on the upper surface of the electrodes disposed below the pair of electrodes.   The solid particulate classifier according to any one of claims 1 to 16, further comprising a device for collecting and degassing gas generated from a pair of electrodes.   18. The solid fine particle classifier according to claim 1, further comprising a liquid circulation device for collecting and refluxing the supernatant liquid overflowing the supernatant portion of the suspension. Classification device.   A method for classifying solid fine particles, wherein classification is performed after adjusting the pH concentration of the suspension using the apparatus according to claim 1.   Using the apparatus according to any one of claims 1 to 18, classification is performed by adjusting the voltage applied to the pair of electrodes according to the zeta potential of the solid fine particles in the suspension when classifying the solid fine particles. A method for classifying solid fine particles.

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