JPH105626A - Centrifugal separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently divide a particle group in a raw liquid slurry into a coarse particle group and a fine particle group to individually separate and recover them by providing first and second centrifugal separators and constituting the first centrifugal separator as a screw type decanter and constituting the second centrifugal separator as a separation plate type decanter. SOLUTION: When a raw liquid slurry S0 is supplied to a screw type decanter 4 from a raw liquid tank 1, the raw liquid slurry is formed into a liquid layer on the entire surface of a cylinder part 43A while being rotated and accelerated by a rotary body 43. A particle group receives centrifugal force in this liquid layer and a coarse particle group P1 is preferentially sedimented and separated in the liquid layer to be precipitated on the inner peripheral surface of the rotary body 43. A supernatant soln. containing a fine particle group P2 is supplied to a separation type decanter 9 as a primary treated soln. S1 and rotated and accelerated by a rotary body 93 and, during this period, particles having a relatively large particle size are sedimented and separated. Further, remaining residual fine particles are separated on the surfaces of opposed vertical passing separation plates 95 separated by a slight normal line distance to obtain a clear separated soln. S2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal separator, and more particularly, to processing a stock slurry having a wide range of particle size distribution of solid particles by using a screw type decanter to increase the particle size from an arbitrary particle size to a large particle size. Coarse particle group (for example, 10 to 10
0 μm) and a group of fine particles having a small particle size (for example, 0.5 to
10 μm) and a centrifugal separator capable of collecting solid particles.

[0002]

2. Description of the Related Art In the inorganic chemical industry and the like, a method of generating crystals in a reaction vessel, evaporating and concentrating a crystal-containing liquid, and then centrifuging to collect the crystals is generally used. In this case, the particle size distribution of the crystal particles becomes wider than a predetermined range due to a difference in reaction conditions, and crystals larger than a certain particle size may not be suitable for use as a product. In such a case, after first separating and collecting crystal particles having a certain particle size in the stock slurry, the crystal particles having a certain particle size are used as a product, and the crystal particles having a size larger than the certain particle size are collected. The crystal particles are returned to the reaction solution and redissolved, and if they can be reused as raw materials, the product yield can be greatly improved.

[0003] The present applicant has previously disclosed in Japanese Patent Publication No. Sho 63-2218 as a centrifugal separator having excellent performance for separating and removing solid fine particles in a raw material slurry by vertically separating a screw type decanter in the axial direction. We proposed a decanter with a large number of plates and a large settling area. Since this decanter has a structure in which the sedimentation area is made large by a large number of vertical separation plates, it exerts great power in removing fine particles in the stock slurry.

[0004]

However, in the case of the decanter with a separating plate proposed in the above-mentioned publication, since the sedimentation area is large through a large number of vertical separating plates as described above, the undiluted solution is used. When removing fine particles in the slurry, it exerts great power, but because the spacing between the vertical separation plates is narrow, the particle size distribution of the particles in the raw material slurry is wide, including coarse particles with a large particle size In this case, coarse particles are clogged in the gaps between the vertical separation plates, so that the coarse particles cannot be separated and collected, and thus cannot be separated and collected into a plurality of particles having different particle size distributions. There was a problem that.

The present invention has been made to solve the above problems, and has a wide particle size distribution of particles in a stock slurry.
It is an object of the present invention to provide a centrifugal separator capable of separating a raw liquid containing a group of particles ranging from fine particles to coarse particles into a coarse particle group and a fine particle group, and separating and collecting each of them individually.

[0006]

A centrifugal separator according to a first aspect of the present invention comprises a first centrifuge for primary processing of a stock solution to separate a first particle group, and a processing by the first centrifuge. A second centrifugal separator for secondary-treating the liquid to separate a second particle group, wherein the first centrifuge has a rotating rotary drum, and a speed difference between the rotating rotary drum and the rotary drum. Is configured as a screw-type decanter having a screw conveyor that rotates with the second centrifuge, a rotating rotary drum,
A screw conveyor inscribed in the rotary drum and rotating at a different speed from the rotary drum; and a screw conveyor interposed over a predetermined range between the outer periphery of the screw conveyor and the inner diameter of the screw conveyor, and having an inclination angle with respect to the radial direction. And a plurality of vertical separation plates radially arranged at a small interval from each other.

According to a second aspect of the present invention, there is provided a centrifugal separator according to the first aspect, wherein the rotating drum and the screw conveyor of the screw type decanter have variable rotational speeds, and the respective rotational speeds are variable. It is characterized in that the particle size distribution of the first particle group and the second particle group is adjusted by adjusting the number.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the embodiments shown in FIGS. FIG. 1 is a configuration diagram showing an embodiment of the centrifugal separator of the present invention, FIG. 2 is a perspective view showing a separation plate stack of the separation plate type decanter shown in FIG. 1, and FIG.
Is an explanatory view for explaining the operation of the separation plate stack shown in FIG. 2,
FIG. 4 is a system diagram showing another embodiment of the centrifugal separator of the present invention.

The centrifugal separator according to the present embodiment processes a stock slurry containing solid particles having a wide particle size distribution, and separates a coarse particle group having a large particle size and a small particle group having a small particle size from the stock slurry. Can be suitably used when separating and recovering. In this case, the principle of centrifugation is, as is well known, the sedimentation velocity (V
P) makes use of Stokes' law, which is proportional to d ² G. Here, d is the particle size, and G is the gravitational acceleration.
Therefore, as a specific example of dividing into various particle groups, for example, when a pigment for paint is divided into various particle diameters, or in the semiconductor manufacturing field, for example, polishing debris generated when polishing the surface of a silicon wafer, etc. For example, there may be mentioned a case where the particles are separated from the grains.

When aluminum, for example, is divided into a plurality of particle groups as a pigment for a paint, the coarse particle groups are separated at, for example, 30G, and the separated coarse particle groups are returned to a pulverizing step which is a preceding step. For example, an intermediate particle group is separated at 300G, and the separated intermediate particle group is used as a raw material of a heat-resistant paint. For example, a fine particle group is separated at 3000G, and the separated fine particle group is used as a raw material of a metallic paint for an automobile. You. In addition, polishing debris (silicon particles) and abrasive grains (eg, ceramic fine particles) during surface polishing of a silicon wafer
In the case of dividing, the abrasive particles as coarse particles are separated at, for example, 100 to 900 G, the separated abrasive particles are collected and provided for reuse, and the silicon abrasive particles as fine particles Are separated at, for example, 1000-3500G,
The separated particles are discarded.

Next, the centrifugal separator of the present embodiment will be specifically described. The centrifugal separator of the present embodiment is shown in FIG.
As shown in FIG. 2, a stock solution tank 1 for storing a stock solution slurry S0 is connected to the stock solution tank 1 via a pipe 2 and a pump 3, and the stock solution slurry S0 is subjected to a primary treatment to obtain a first particle group (hereinafter referred to as "coarse particles"). A first centrifuge 4 that separates and discharges P1 and discharges the primary processing liquid S1.
And an intermediate tank 6 connected to the first centrifuge 4 via a pipe 5 and recovering the primary processing liquid S1, and an intermediate tank 6 connected to the intermediate tank 6 via a pipe 7 and a pump 8, and A second centrifugal separator 9 for secondary processing of S1 to separate and discharge a second particle group (hereinafter, referred to as "particle group") P2 and discharge a clear separated liquid S2 after the secondary processing.
And a separation liquid tank 11 which is connected to the second centrifuge 9 via a pipe 10 and collects the separation liquid S2.

The first centrifugal separator 4 is connected via a pipe 12 to a slurry containing the separated coarse particles P1 (hereinafter referred to as a slurry).
This is referred to as “coarse particle slurry”. ) A coarse particle slurry tank 13 for recovering S3 is connected, and a second centrifuge 9
Is connected via a pipe 14 to a fine particle slurry tank 16 for collecting a slurry S4 containing the separated fine particle group P2 (hereinafter, referred to as "fine particle slurry").

Thus, the first centrifuge 4 is configured as a screw type decanter, and the second centrifuge 4 is configured as a separation plate type decanter. Therefore, in the following, the first
The centrifugal separator 4 is a screw type decanter 4, and
The second centrifuge 4 will be described as a separation plate type decanter 4.

As shown in FIG. 1, the screw type decanter 4 comprises a horizontal cylindrical casing 41 and a rotating drum 43 rotating via bearings 42, 42 disposed at the center of both ends of the casing 41. A screw conveyor 44 that is inscribed in the rotating drum 43 and rotates with an appropriate differential speed from the rotating drum 43, and a speed reducer 45 that rotationally drives the rotating drum 43 and the screw conveyor 44 with an appropriate differential speed, The coarse particles P1 are separated from the stock slurry S0 by centrifugal force caused by the high-speed rotation of the rotating drum 43, and the screw conveyor 4
At 4, the coarse particles P1 are transferred to the frusto-conical shape of the rotary drum 43. The rotational speed of the rotating drum 43 and the screw conveyor 44 can be appropriately adjusted by the speed reducer 45 in accordance with the particle size of the coarse particle group P1 to be separated.

As shown in FIG. 1, the rotary drum 43 has a cylinder portion 43A forming a separation zone where the coarse particle group P1 precipitates with the outer periphery of the screw conveyor 44, and a frusto-conical shape provided continuously therewith. And a cone section 43B formed as a concentration zone of the same. In addition, the cylindrical shaft support 4
The feed pipe 46 is coaxially inserted into 3C, and the feed pipe 46
The stock solution slurry S0 is supplied into the cylinder section 43A via the. Accordingly, the undiluted slurry S0 supplied into the cylinder portion 43A forms a liquid layer covering the inner peripheral surface of the cylinder portion 43A, and the coarse particles P1 receive the centrifugal force due to the centrifugal force caused by the high speed rotation of the rotating drum 43. It precipitates in the liquid layer, is separated from the fine particles P2, and is subjected to primary treatment.

A plurality of first drain holes 43D are formed on the end plate of the cylinder portion 43A at the same radius at predetermined intervals in the circumferential direction, from which the primary processing liquid S1 overflows, and The liquid is discharged to the first drainage chamber 41A of the first liquid discharge chamber 41. On the other hand, a plurality of second drain holes 43E are formed on the peripheral surface of the distal end portion of the cone portion 43B at predetermined intervals in the circumferential direction.
To the second drain chamber 41B. Also,
A ring-shaped ring dam 47 for partially closing the first drainage hole 43D disposed on the same radius is attached, and the first drainage hole 43D is closed by the ring dam 47 so that the primary treatment liquid S1 is removed. The concentration of the coarse particles P1 is adjusted by adjusting the liquid layer height in the rotating drum 43 and adjusting the liquid component of the coarse particle slurry S3.

On the other hand, the screw conveyor 44 has a first screw blade 44A spirally formed so as to be inscribed in the inner peripheral surface of the cylinder portion 43A, and a spiral so as to be inscribed in the inner peripheral surface of the cone portion 43B. The second formed in the shape
Screw blade 44B and shaft portion 44 to which these are fixed
C, and the coarse particles P1 precipitated in the separation zone
The second drainage hole 4 is formed by the second screw blades 44A and 44B.
It is transported to the 3E side.

A liquid supply pipe 46 is inserted into the shaft 44C of the screw conveyor 44. In the shaft portion 44C, liquid supply holes 44E are formed in the vicinity of the boundary between the separation zone and the concentration zone at equal intervals in the circumferential direction, and supplied from the liquid supply pipe 47 through these liquid supply holes 44E. The thus-prepared stock solution slurry S0 is supplied while being dispersed into the rotating drum 43 as shown by the arrow in FIG. 1, so that the stock solution slurry S0 is subjected to primary treatment.

As shown in FIG. 1, a separating plate type decanter 9 disposed on the downstream side of the screw type decanter 4 is provided with a horizontal cylindrical casing 91 and a central portion at both ends of the casing 91. A rotating drum 93 that rotates via a bearing (not shown) provided, a screw conveyor 94 that is inscribed in the rotating drum 93 and rotates at an appropriate speed difference from the rotating drum 93, and a shaft of the screw conveyor 94. It comprises a number of longitudinal separating plates 95 mounted between the outer periphery and the inner diameter of the screw conveyor 94, and a speed reducer 98 for rotating the rotating drum 93 and the screw conveyor 94 at an appropriate differential speed. The fine particles P2 are separated from the primary treatment liquid S1 by centrifugal force by the screw conveyor 94.
To transfer the fine particles P2 to the truncated cone of the rotary drum 93. The rotational speed of the rotary drum 93 and the screw conveyor 94 can be appropriately adjusted by a speed reducer 98 in accordance with the particle size of the particle group P2 to be separated.

The rotary drum 93 has substantially the same structure as the rotary drum 43 of the screw type decanter 4. That is, the rotary drum 93 is formed with a cylinder portion 93A and a cone portion 93B. First and second drain holes 93 are provided at the end wall of the cylinder portion and the tip of the cone portion 93B, respectively.
D and 93E are formed, and the separated liquid S2 flows out from the first drainage hole 93D, and the fine particle slurry S4 flows out from the second drainage hole 93E. The first drain hole 93D is provided with a ring dam 99 for closing a part of the first drain hole 93D to adjust the liquid layer height in the rotating drum 93.

The screw conveyor 94 includes a first screw blade 94A spirally formed so as to be inscribed in an inner peripheral surface of the cylinder portion 93A, and a cone portion 93B.
A second screw blade 94B spirally formed so as to be inscribed on the inner peripheral surface of the first screw blade 94B, and a shaft portion 94C to which the second screw blade 94B is fixed are provided. The second screw blades 94A and 94B transfer the liquid to the second drain chamber 91B. A liquid supply pipe 96 is inserted into the shaft portion 94C so that the primary processing liquid S1 is supplied to the rotating drum 93 while being dispersed through the liquid supply hole 94E. The liquid supply hole 94E is located near the end of the vertical separation plate 95 on the side of the cone 93B.

As shown in FIGS. 3 and 4, each of the vertical separation plates 95 is a plate formed in a rectangular shape and fixed radially over the entire outer peripheral surface of the tubular member 95A. A tubular member 95A formed as a separator stack
Through the shaft 94C. As shown in FIG. 4, each longitudinal separation plate has a cylinder 93 near the inner end.
A predetermined inclination angle θ (for example, 10 ° to
60 °). Further, the vertical separation plates 95 are separated from each other at a small interval (for example, 1.0 to 10.0 mm), and as shown in FIG. 4, the sedimentation distance of the fine particle group P2 settling outward in the radial direction is shortened to L1. Then, the fine particle group P2 is efficiently captured. Screw conveyor 9
If the vertical separation plate 95 is not provided in 4, the particle group P2 must settle directly to the inner peripheral surface of the rotary drum 93, and the settling distance becomes long, so that the particle group P2 can hardly be captured. Also,
The inner peripheral end of the first screw blade 94A is fixed to the outer peripheral end of the plurality of vertical separating plates 95, and is spirally surrounded by the first screw blades 94A along the axial direction of the vertical separating plate 95. Since the first screw blade 94A rotates at a speed different from that of the rotary drum 93, the fine particle group P2 that has slid from each longitudinal separation plate 95 and settles on the inner peripheral surface of the rotary drum 93 is concentrated by the first screw blade 94A. To be transferred to

The operation of the centrifugal separator used for separating the crystal-containing liquid composed of the group of coarse particles and the group of fine particles produced in the reaction vessel by the centrifugal separator of the present invention having the above-described structure will be described. As the coarse particle group, for example,
It is assumed that the fine particles have a particle size distribution of, for example, 0.5 to 10 μm.

When the stock slurry S0 is to be treated, first, the stock slurry S0 is supplied from the stock tank 1 to the screw type decanter 4 of the centrifugal separator by the pump 3 via the pipe 2, and the stock slurry S0 is then screwed. The primary processing is performed in the decanter 4 as follows. That is, when the stock solution slurry S0 is continuously supplied from the liquid supply pipe 46 into the screw type decanter 4, the stock solution slurry S0 is dispersed and supplied to the rotating body 43 through the solution supply hole 44E. Since the stock solution slurry S0 is rotated at an acceleration of about 900 G, a liquid layer is formed on the entire surface of the cylinder portion 43A while the rotation of the stock solution slurry S0 is accelerated, and the liquid layer height is gradually increased. In this liquid layer, the particles are subjected to centrifugal force, and, for example, coarse particles P1 having a size of 10 to 100 μm are preferentially settled and separated in the liquid layer and settled on the inner peripheral surface of the rotating drum 43, and have a particle size of 0.5 to 10 μm. The group P2 does not sink at such an acceleration but floats. Then, the stock slurry S0
When the liquid layer rises due to the continuous supply of the liquid, the supernatant liquid containing the fine particle group P2 overflows from the first drain hole 43D as the primary processing liquid S1, and this primary processing liquid S1 passes through the first drain chamber 41A and the pipe 5. And flows into the intermediate tank 6 where it is collected.

On the other hand, the coarse particle group P1 settled on the inner peripheral surface of the rotating drum 43 is transferred to the enrichment zone of the cone portion 43B by the first screw blade 44A rotating at a speed slightly slower than that of the rotating drum 43, and gradually there. Becomes the coarse particle slurry S3 that has been dewatered. The coarse particle slurry S3 is supplied to the second drain hole 43.
As it approaches E, the cone portion 43B is scraped up and gradually drained, and flows out from the second drain hole 43E to the second drain chamber 41B as a high-concentration coarse particle slurry S3 via the pipe 12 It flows out to the coarse particle slurry tank 13 and is collected here.

The primary processing liquid S1 collected in the intermediate tank 6
Is supplied to the separation plate type decanter 4 via a pipe 7 by a pump 8, and a secondary treatment is performed as described below. That is, when the primary processing liquid S1 is supplied into the separation plate type decanter 9 from the liquid supply pipe 97, the primary processing liquid S1 is rotationally accelerated to the rotating drum 93 through the liquid supply hole 94E at an acceleration of, for example, 1000 to 3500G. While being distributed to the separation zone. In the separation zone, particles having a relatively large particle size among the fine particles P2 are first settled and separated. Further, the primary processing liquid S1 is distributed and flows into the small gaps between the vertical separation plates 95, and this flow becomes laminar between the vertical separation plates 95. While the primary processing liquid S1 flows through this area, the remaining fine particles P remaining in the primary processing liquid S1 face each other only by a small normal line distance between the vertical separation plates 95 as shown by arrows in FIG. The liquid is separated on the surface of the vertical separation plate 95, which becomes a clear separation liquid S2. The separated liquid S2 flows from the first drain hole 93D to the first drain chamber 91A, flows to the separated liquid tank 11 via the pipe 10, and is collected here.

On the other hand, the fine particles P2 settled on the vertical separation plate 95 slide along the vertical separation plate 95 due to centrifugal force.
The first screw blades 94A on the outer periphery of the vertical separation plate 95 settle in the sludge space around which the first screw blades 94A are wound. At this time, the fine particle group P2 settled in the sludge space is transferred to the cone portion 94B by the first screw blade 94A rotating at a speed slightly slower than the rotating drum 93, and becomes a fine particle slurry S4.
Even in the fine particle slurry S4, the fine particle group P2 is subjected to centrifugal force and is dewatered.
B is fried and further drained. Finally, the high-concentration fine particle slurry S4 is supplied to the second drain hole 9
It flows out from 3E into the second drain chamber 91B and is collected in the fine particle slurry tank 16 via the pipe 14.

As described above, according to the present embodiment,
A first centrifugal separator 4 for primary processing of the stock solution slurry S0 to separate the coarse particle group P1, and a second centrifugal separation for secondary processing of the primary processing liquid S1 by the first centrifuge 4 to separate the fine particle group P2 The first centrifugal separator 4 comprises a rotating drum 43 and a screw conveyor 44 inscribed in the rotating drum 43 and rotating at a different speed from the rotating drum 43 as a screw-type decanter. The second centrifugal separator 9 includes a rotating rotating drum 93, a screw conveyor 94 inscribed in the rotating drum 93 and rotating at a different speed from the rotating drum 93, and a shaft 94 of the screw conveyor 94.
A plurality of longitudinal separation plates 95 interposed over a predetermined range between the outer periphery of C and the inner diameter of the screw conveyor 94 and having an inclination angle with respect to the radial direction and radially arranged at small intervals from each other. Is constituted as a separation plate type decanter equipped with the raw material slurry S0, the particle size distribution of the particles in the raw solution slurry S0 is wide, and the raw solution slurry S containing particles ranging from fine particles to coarse particles.
Even if it is 0, it can be surely divided into the coarse particle group P1 and the fine particle group P2, and each can be separated and collected individually.

Further, according to the present embodiment, the rotating drum 43 and the screw conveyor 44 of the screw type decanter 4 have their respective rotation speeds variable via the speed reducer 45, and the respective rotation speeds are adjusted to adjust the coarse particles. Since the particle size distribution of the group P1 is adjusted, even if the size of the average particle size fluctuates, the number of rotations of the rotating drum 43 and the screw conveyor 44 is changed in accordance with the average particle size to ensure that. Coarse particle group P
1 can be separated and recovered. The same can be said for the separation plate type decanter 9.

FIG. 5 is a view showing another embodiment of the present invention. The centrifugal separator of this embodiment comprises a coarse particle group P1 and
It is divided into a fine particle group P2 and an intermediate particle group P3 having an average particle diameter between these groups, and separates and collects them individually. For example, when the above-mentioned paint pigment is divided into three types, Used. Centrifuge 51 of the present embodiment
Is arranged on the downstream side of a mill 52 for crushing the solid raw material, as shown in FIG. And this centrifugal separator 5
1 is a screw type decanter for separating the coarse particle group P1
1A, a first separation plate type decanter 51B of medium rotation speed for separating the intermediate particle group P3, and a second separation plate type decanter 51C of high speed rotation for separating the fine particle group P2. Each of the decanters 51A, 51B, The particles separated in 51C are collected in the respective tanks 53A, 53B, 53C. The screw-type decanter 51A has the same configuration as the screw-type decanter 4 described above, and the first and second separation-type decanters 51B and 51C have the same configuration as the above-described separation-plate decanter 9. According to the present embodiment, even a particle group having three types of particle size distribution is surely divided into a coarse particle group P1, a fine particle group P2, and an intermediate particle group P3 having an average particle diameter between these groups. , Can be separated and recovered individually.

[0031]

According to the first aspect of the present invention, the particle size distribution of the particles in the stock solution slurry is wide, and even if the stock solution contains a particle group ranging from fine particles to coarse particles, the coarse particle group And a fine particle group, and a centrifugal separator for individually separating and recovering each of them can be provided.

According to the second aspect of the present invention, there is provided a centrifugal separator for reliably separating and recovering the first particle group even if the average particle diameter of the first particle group fluctuates. Can be

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of a centrifugal separator of the present invention.

FIG. 2 is a perspective view showing a separation plate stack of the separation plate type decanter shown in FIG. 1;

FIG. 3 is an explanatory diagram for explaining an operation of the separation plate stack shown in FIG. 2;

FIG. 4 is a system diagram showing another embodiment of the centrifugal separator of the present invention.

[Explanation of symbols]

 4 Screw-type decanter (first centrifuge) 9 Separator-type decanter (second centrifuge) 43, 93 Rotating drum 44, 94 Screw conveyor 95 Vertical separation plate

Claims (2)

[Claims] 1. A first centrifugal separator for primary processing of a stock solution to separate a first particle group, and a second centrifugal separator for secondary processing of a processing liquid by the first centrifuge to separate a second particle group. The first centrifuge is configured as a screw-type decanter having a rotating rotary drum, and a screw conveyor inscribed in the rotary drum and rotating at a different speed from the rotary drum. The centrifugal separator includes a rotating rotating drum, a screw conveyor inscribed in the rotating drum and rotating at a different speed from the rotating drum, and a predetermined range between the outer periphery of the screw conveyor shaft and the inner diameter of the screw conveyor. A centrifugal separator configured as a separation plate type decanter including a number of vertically separated separation plates interposed and inclined at an angle to the radial direction and arranged radially at a small interval from each other. Separation device. 2. The rotating drum and the screw conveyor of the screw type decanter have variable rotation speeds.
The first particle group and the second particle group can be adjusted by adjusting the respective rotation speeds.
2. The method according to claim 1, wherein the particle size distribution of the particles is adjusted.
A centrifugal separator as described.