JPH0760009A - Sedimentation type solid-liquid separator - Google Patents

Abstract

(57) [Summary] [Object] To provide a sedimentation-type solid-liquid separation apparatus or a solid-liquid sedimentation separation method, which can significantly reduce the residence time of solid components and can be used even in a pressurized state. [Structure] The raw slurry agglomerated by the line mixer 15 is supplied to a slurry blowing member 3 through a slurry supply passage 2 and then blown radially outward from a slurry outlet 17 into a sedimentation separation tank 1. Therefore, almost no liquid flow occurs below the slurry blowing member 3, and the sedimentation speed of the solid component (floc) is increased. Then, the slurry blowing member 3 is arranged close to the concentrated slurry layer interface L _1, and the sedimentation distance of the solid-liquid component becomes short. Therefore, the residence time of the solid component is significantly reduced. Also, the sedimentation tank 1
As a closed structure, it is possible to perform solid-liquid separation under pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sedimentation-type solid-liquid separation device for obtaining a clear liquid and a concentrated slurry by performing solid-liquid separation by utilizing the sedimentation phenomenon of solid components in slurry by gravity. Is. More specifically, the present invention relates to a sedimentation-type solid-liquid separation device having a rapid sedimentation separation ability that enables downsizing of the device and high production efficiency.

[0002]

2. Description of the Related Art A slurry prepared by mixing a liquid component and a solid component without melting each other is used to make a clear liquid containing substantially no solid component and a solid component by utilizing the sedimentation phenomenon of the solid component due to gravity. A sedimentation-type solid-liquid separation device that separates a concentrated slurry having a high concentration has been conventionally known. In addition, such a sedimentation type solid-liquid separation apparatus is generally called a thickener in view of obtaining a concentrated slurry, or a clarifier in view of obtaining a clarified liquid. In addition, a sedimentation-type solid-liquid separation device in which a raw slurry or a raw liquid is subjected to a coagulation treatment in the device is generally called a coagulation sedimentation device.

Generally, such sedimentation type solid-liquid separators are roughly classified into so-called non-contact type solid-liquid separators and contact type solid-liquid separators. Here, the non-contact type solid-liquid separation device is a type of sedimentation-type solid-liquid separation device in which flocs (solid components) are sequentially and monotonically settled in the settling separation tank and deposited on the bottom. For example, a so-called upflow type thickener (clarifier) as shown in FIG. 4 or a horizontal flow type coagulating sedimentation device as shown in FIG. 5 has been conventionally known.

As shown in FIG. 4, an upflow thickener 10 is provided.
0 is substantially the sedimentation separation tank 101 and the feed well 10.
2 and the peripheral gutter 103, and the original slurry is supplied to the upper part of the feed well 102. Here, in the settling / separating tank 101, a clarifying layer 104 made of a clarifying liquid, a settling layer 105 in which a solid component is being settled, and a concentrated slurry layer 106 in which the solid component is deposited are sequentially arranged from the upper side.
And are formed. Then, while the clarified liquid flows out from the peripheral gutter 103, the concentrated slurry is drawn out from the bottom of the sedimentation separation tank 101. The sedimentation separation tank 101 is provided with a mud collecting device 107 that collects sludge accumulated on the bottom of the sedimentation separation tank 101.

Further, as shown in FIG. 5, in the horizontal flow type coagulation-sedimentation apparatus 110, the stock solution or the slurry is coagulated in the two flocculators 111 and 112, and then solid-liquid in the sedimentation separation tank 113. The separated liquid is discharged through the clarifying liquid tank 114, and the sludge (concentrated slurry) is discharged through the sludge ditch 115. In addition, sedimentation separation tank 1
13, sludge accumulated on the bottom of the sludge is discharged into the sludge groove 115.
A mud collecting device 116 is provided for collecting.

On the other hand, the contact-type solid-liquid separation device captures the small-diameter flocs in the large-diameter flocs by contacting or mixing the small-diameter flocs newly supplied or generated with the large-diameter flocks that have already been formed. A flocculation-type solid-liquid separator of the type in which flocs are enlarged to enhance their sedimentation property. Specifically, for example, a slurry blanket-type coagulating sedimentation device as shown in FIG. 6 and FIG. A slurry circulation type coagulation-sedimentation device as shown, or an external circulation type coagulation-sedimentation device as shown in FIG.
No. 8-174209) is conventionally known.

As shown in FIG. 6, in the slurry blanket type flocculation-precipitation apparatus 120, after the stock solution or the raw slurry is coagulated in the rapid stirring tank 121, the slow stirring tank 122 is used.
The slurry in the slow stirring tank 122 further flows into the sedimentation separation tank 124 as indicated by an arrow Y ₁ . Here, a clarification layer 125 is formed in the upper part of the settling separation tank 124, and a sludge layer 126 (concentrated slurry layer) is formed in the lower part, and the slurry that has flowed into the settling separation tank 124 is the sludge layer 126. It passes through and reaches the clearing layer 125. At that time, the small diameter flocs in the slurry are sludge layer 1
It is captured by the large diameter flocs in 26. Then, the clarified liquid is discharged through the conduit 127, and the sludge is separated into the sedimentation tank 1
It is pulled out from the bottom of 24.

As shown in FIG. 7, in the slurry circulation type coagulation-sedimentation apparatus 130, the stock solution is coagulated in the primary stirring chamber 131, then flows into the secondary stirring chamber 132, and then the secondary stirring chamber 132. A part of the slurry in 132 is returned to the primary stirring chamber 131 through the circulation chamber 134 as shown by an arrow Y ₂ .
Here, in the primary stirring chamber 131, the newly generated small-diameter flocs are mixed with the circulated large-diameter flocks, the small-diameter flocs are captured by the large-diameter flocs, and the flocs are enlarged. , The flocculating property is enhanced. A part of the slurry in the secondary stirring chamber 132 is indicated by an arrow Y ₃
As shown in (3), the solid solution is separated into the sedimentation / separation chamber 133, the clear liquid is discharged through the drain 135, and the sludge is extracted from the bottom of the sedimentation / separation chamber 133.

Further, as shown in FIG. 8, in the external circulation type coagulation-sedimentation apparatus 140, the stock solution is coagulated in the feed supply pipe 141 using the agitator 142 and then flows into the sedimentation separation tank 143. Then, in the settling separation tank 143, from the upper side, the clarifying layer 144 and the floc floc layer 14 are sequentially arranged.
5 and the concentrated sludge layer 146 (concentrated slurry layer) are formed, the clarified liquid is discharged through the overflow section 147, and the concentrated sludge is drawn out from the bottom of the sedimentation separation tank 143. Here, a part of the concentrated sludge is returned to the feed supply pipe 141 by using the return pump 148,
In 1, the newly generated small-diameter flocs are mixed with the returned large-diameter flocs, the small-diameter flocs are captured by the large-diameter flocs, the flocs are enlarged, and the sedimentation of the flocs is enhanced. To be

All of the conventional sedimentation type solid-liquid separators described above are low in construction cost and operation cost as compared with other types of solid-liquid separators, such as a filter press, and the maintenance thereof is easy. There is an advantage such as. For this reason, the sedimentation type solid-liquid separation device has heretofore been widely used in a process requiring solid-liquid separation in a manufacturing process in various industrial fields. Specifically, for example, in the step of separating the insoluble residue from the sodium aluminate solution in the production of alumina using bauxite as the raw material by the Bayer method, or the step of separating the precipitated aluminum hydroxide from the sodium aluminate solution, etc. To be

[0011]

A conventionally known settling type solid-liquid separator, for example, an upflow type thickener 1 as shown in FIG.
At 00, it takes a long time for the solid components in the feed well 102 to settle in the sedimentation layer 105 and reach the concentrated slurry layer 106, which lengthens the residence time of the solid components. Then, it seems that a method of arranging the feed well 102 at a lower position to lower the feed position of the raw slurry and shortening the time required for the sedimentation of the solid component can be seen at first glance. Well 10
The concentrated slurry layer 106 is disturbed by the flow of the slurry that is blown downward from 2, and the flocs in the concentrated slurry layer 106 rise up.

A horizontal flow type coagulating sedimentation apparatus 1 as shown in FIG.
No. 10 also has a problem that it takes a long time for the solid component to settle in the sedimentation separation layer 113, and the concentrated slurry layer deposited at the bottom of the sedimentation separation layer 113 is insufficiently compressed or concentrated. In addition, the mud collecting device 116 having a complicated structure must be provided.

In the slurry blanket type coagulation-sedimentation apparatus 120 as shown in FIG. 6, it is necessary to retain a large amount of solid components in the sludge layer 126 in order to capture the small diameter flocs, which results in a long residence time of the solid components. . Further, in the slurry circulation type coagulation-sedimentation apparatus 130 as shown in FIG. 7 or the external circulation type coagulation-sedimentation apparatus 140 as shown in FIG. 8, the solid component is circulated or returned, so that the residence time of the solid component is inevitable. Becomes longer.

As described above, in the conventional settling type solid-liquid separation apparatus, a new flocculant was developed and it became possible to form a large-sized floc, and although it was considerably improved, the separation time between the liquid component and the solid component was improved. Is relatively long, the miniaturization of equipment and high production efficiency cannot be expected, and there are problems such as an increase in capital investment and an increase in operating cost. The present invention has been made in view of the above knowledge and consideration in order to solve the above-mentioned conventional problems, and enables solid-liquid separation in a short time, and has excellent separation efficiency. It is an object of the present invention to provide a sedimentation type solid-liquid separator having a small size and high production efficiency.

[0015]

In order to achieve the above object, the first invention is a settling separation tank for causing an upward total flow of a liquid component in a slurry while allowing a solid component in the slurry to settle by gravity. , A slurry blowing member for blowing out the raw slurry supplied through the slurry supply passage in a substantially horizontal direction in the sedimentation separation tank, a clear liquid discharge means for discharging the clear liquid from the upper part of the sedimentation separation tank, and a concentration from the lower part of the sedimentation separation tank A sedimentation type solid-liquid separation device is provided, which is provided with a concentrated slurry discharging means for discharging a slurry.

A second aspect of the present invention is the sedimentation-type solid-liquid separation device according to the first aspect of the present invention, wherein the settling separation tank has a straight barrel portion and an upwardly widening tapered portion adjacent to a lower side of the straight barrel portion. Provided is a sedimentation-type solid-liquid separation device, wherein the formed slurry blowing member is disposed in the vicinity of an interface of a concentrated slurry layer formed in the solid-liquid separation tank.

According to a third aspect of the present invention, in the sedimentation-type solid-liquid separation device according to the first aspect of the present invention, the settling separation tank has a straight body portion and an upwardly widening taper portion adjacent to the lower side of the straight body portion. The formed slurry blowing member is arranged near the interface of the concentrated slurry layer formed in the solid-liquid separation tank, and is arranged at a position around the center of the sedimentation separation tank in the horizontal direction. There is provided a sedimentation-type solid-liquid separation device, characterized in that a slurry outlet of the member is opened outward in the radial direction of the sedimentation separation tank.

A fourth aspect of the present invention is the sedimentation-type solid-liquid separation device according to the first aspect of the present invention, wherein the settling separation tank has a straight body portion and an upwardly widening taper portion adjacent to the lower side of the straight body portion. The formed slurry blowing member is arranged in the vicinity of the interface of the concentrated slurry layer formed in the solid-liquid separation tank and in the horizontal direction in the vicinity of the inner wall of the settling separation tank, and the slurry is blown out. There is provided a sedimentation-type solid-liquid separation device characterized in that a slurry outlet of a member is opened inward of a sedimentation separation tank.

A fifth aspect of the present invention is the sedimentation type solid-liquid separator according to any one of the first to fourth aspects of the present invention,
Provided is a sedimentation-type solid-liquid separation device, characterized in that coagulation treatment means for coagulating the raw slurry by adding a coagulant is provided in a step before the slurry supply passage.

A sixth invention is the sedimentation-type solid-liquid separation device according to any one of the first to fourth inventions described above,
An aggregating means for adding an aggregating agent to agglomerate the raw slurry is provided in a step before the slurry supply passage, and a slow agitating means for slowly agitating the concentrated slurry layer formed in the lower part of the sedimentation separation tank is allowed to settle. Provided is a sedimentation type solid-liquid separation device, which is provided in a separation tank.

The apparatus of the present invention will be described below with reference to the drawings, but the following example is one embodiment of the apparatus of the present invention and does not limit the apparatus of the present invention. First, with reference to FIG. 1, a sedimentation type solid-liquid separator (hereinafter referred to as thickener) of atmospheric pressure specification will be described. As shown in FIG. 1, the thickener T1 of normal pressure specifications is provided with a slurry supplied through a slurry supply passage 2 and a slurry blowing member 3 in a settling separation tank 1.
Utilizing the gravity settling phenomenon of non-soluble solid components (hereinafter simply referred to as solid components) in the slurry, the liquid is separated into a clarified liquid and a concentrated slurry, and the clarified liquid is passed through an overflow gutter 4 and a clarified liquid discharge passage 5. The concentrated slurry is discharged to the outside through the concentrated slurry discharge passage 6. The thickener T1 corresponds to the above-mentioned "sedimentation type solid-liquid separator". The assembly consisting of the overflow gutter 4 and the clear liquid discharge passage 5 corresponds to the above-mentioned "clarified liquid discharge means", and the concentrated slurry discharge passage 6 corresponds to the above-mentioned "concentrated slurry discharge means".

The main body of the settling separation tank 1 is composed of a cylindrical straight body portion 1a and an upwardly expanding hollow conical taper portion 1b adjacent to the lower side of the straight body portion. Incidentally. Here, the upwardly widening taper portion 1b adjacent to the lower side of the straight body portion 1a has a hollow conical shape, but the shape is not limited to such a conical shape, and for example, the bottom has a rounded shape. It may have a shape, that is, an end plate shape. Here, the upper end of the straight body portion 1a is open to the atmosphere, while the lower end of the tapered portion 1b is closed to the atmosphere and is connected to the concentrated slurry discharge passage 6. An overflow gutter 4 for receiving the clarified liquid overflowing from the settling separation tank 1 is attached to the outer peripheral surface of the straight body portion 1a near the upper end thereof. Furthermore, a notch 8 (V-shaped cut) is provided at the upper end of the straight body portion 1a for causing the clearing liquid to overflow.
A bridging member 9 is provided so as to straddle the settling / separating tank 1 (the straight body portion 1a) in the diametrical direction, and an end of the bridging member 9 is fixed to an outer peripheral portion of the overflow gutter 4.

A rake 10 is arranged in the settling / separation tank 1, and the rake 10 extends downward in the horizontal frame portion 10a extending in the radial direction of the straight body portion 1a and both end portions of the horizontal frame portion 10a. A vertical frame portion 10b provided, a slant frame portion 10c extending from a lower end portion of the vertical frame portion 10b substantially along the inner peripheral surface of the taper portion 1b, and a plurality of slant frame portions 10c attached to the slant frame portion 10c. It is composed of a blade 11. Rake 10 was mentioned above
It corresponds to "slow stirring means". In the present invention, in addition to the mud collecting effect mainly by the blade 11, the slow stirring means performs liquid removal from the concentrated slurry by means of the slant frame portion 10c and the like to accelerate the concentration of the slurry in the concentrated slurry layer. In addition, in order to more effectively accelerate the drainage of the concentrated slurry, a member for shearing the concentrated slurry layer vertically or horizontally in addition to the slant frame portion 10c, for example, a portion between the central portion and both end portions of the horizontal frame portion 10a. A vertical frame portion 10d may be extended downwardly from the bottom, and the concentrated slurry may be slowly stirred to form a drainage passage in the concentrated slurry. In order to avoid interference with the slurry blowing member 3 or the slurry supply passage 2, the horizontal frame portion 10a is arranged at a position higher than the slurry blowing member 3, and the vertical frame portion 10b is arranged on the peripheral side of the outer periphery of the slurry blowing member 3. ing. And the rake 10
It is connected to a motor 14 via a rotary shaft 12 and a connecting member 13, and is slowly driven to rotate by the motor 14. Here, when the rake 10 is rotationally driven, the concentrated slurry layer 18 formed at the bottom of the sedimentation separation tank 1
Is gently stirred, whereby the sludge removal effect of the concentrated slurry layer 18 is promoted together with the mud collecting effect on the bottom of the solid-liquid separation layer, and the enrichment degree is increased.

The slurry supply passage 2 extends horizontally and penetrates the wall surface of the taper portion 1b in the radial direction to settle and separate the sedimentation tank 1.
After entering the inside, it curves upward and extends upward in the vicinity of the axial center portion of the settling separation tank 1, and is connected to the slurry blowing member 3 at its upper end portion. A coagulant supply pipe 16 for supplying a predetermined coagulant is connected to the slurry supply passage 2 outside the sedimentation separation tank 1. The coagulant supply pipe 16 for supplying the coagulant to the slurry supply passage 2 is capable of forming flocs having a large particle size in the process in which the coagulant is uniformly mixed in the slurry and reaches the slurry blowing member 3. If In FIG. 1, a line mixer 15 (static mixer) is provided in the slurry supply passage 2, and a coagulant supply pipe 16 is connected to the line mixer 15.
In this way, the aggregation process, that is, the formation of flocs is performed outside the thickener T1, so that the thickener T1 has a compact structure. The assembly including the slurry supply passage 2 and the coagulant supply pipe 16 corresponds to the above-mentioned "coagulation processing means".

The slurry blowing member 3 is usually the sedimentation separation tank 1
Is disposed in the vicinity of the center of the axis and between the lower portion of the straight body portion and the central portion of the hollow conical taper. For the purpose of obtaining a clear liquid having excellent clarification property, the slurry blowing member 3 is arranged at a lower portion of the solid-liquid separation tank 1, that is, at a position close to the central portion of the hollow conical taper, and the slurry in the clearing layer is The liquid retention time is set to be long. On the other hand, when it is intended to obtain a concentrated slurry having excellent concentrating properties, the slurry blowing member 3 is arranged in the upper part of the solid-liquid separation tank 1, that is, near the center of the straight body part, and the slurry is concentrated in the concentrated slurry layer. The concentration slurry is set to have a long residence time. In the design of the solid-liquid separation tank 1, unless the installation position of the slurry blowing member 3 can be made variable, that is, when the installation place is fixed, the position of the slurry blowing member 3 can be changed according to a desired purpose. Just decide. In the application of the solid-liquid separation tank, it is essential that the interface L ₁ of the concentrated slurry tank 18 be operated below the slurry blowing member 3 and relatively close to the slurry blowing member 3. In other words, in the present invention, the slurry outlet member 3 is slightly above the surface L ₁ of the thickened slurry layer 18 is disposed relatively close positions on the interface L _1. The position control of the interface L ₁ is performed by increasing or decreasing the discharge speed of the concentrated slurry according to the deviation of the interface position detected by a level sensor (not shown) from the target value.
This is performed by a method of holding the interface L ₁ at a predetermined position (target value).

The slurry blowing member 3 may basically have a structure that blows the slurry in a substantially horizontal direction with respect to the radial direction of the settling / separating tank 1, and the slurry supply passage in the settling / separating tank 1 also settles. Any structure may be adopted as long as it is introduced from either the upper part or the lower part of the separation tank 1 and can communicate with the slurry blowing member 3. In FIG. 1, the slurry blowing member 3 is a closed cylindrical body having a hollow inside. It is arranged so that its axis is oriented in the vertical direction, that is, the peripheral surface faces the inner peripheral surface of the straight body portion 1a. The slurry blowing member 3 communicates with the slurry supply passage 2 at its lower end surface. Further, a plurality of slurry outlets 17 are provided on the peripheral surface of the slurry outlet member 3, and each of these slurry outlets 17 is open outward in the radial direction of the settling separation tank 1. According to this structure, the slurry in the slurry blowing member 3 is blown outward in the radial direction of the settling separation tank 1, that is, in a radial horizontal direction.

In the above structure, the slurry (original slurry) that has been coagulated by the coagulant supplied from the coagulant supply pipe 16 into the slurry supply passage 2 is supplied to the slurry blowing member 3 through the slurry supply passage 2. After this, it is blown out from the slurry outlet 17 into the sedimentation separation tank 1. Here, since the slurry in the slurry outlet 17 is blown radially in the settling / separation tank 1 in the horizontal direction, almost no liquid flow occurs below the slurry blowing member 3. Therefore, the solid component in the slurry that has flowed into the sedimentation separation tank 1 from the slurry blowing member 3 has substantially no interference sedimentation region and sediments in a state close to free sedimentation, so that the sedimentation velocity of the solid component is very high. Get faster And, as mentioned above,
Since the slurry blowing member 3 and the interface L ₁ of the concentrated slurry layer 18 are close to each other, the solid component reaches the interface L ₁ of the concentrated slurry layer 18 in an extremely short time. Therefore, the residence time of the solid component in the settling separation tank 1 becomes very short. Further, since a liquid flow is hardly generated below the slurry blowing member 3, the slurry blowing member 3 is arranged at a position close to the interface L ₁ of the concentrated slurry layer 18,
The characteristic is that the concentrated slurry layer 18 is not disturbed.

The apparatus of the present invention and a conventional sedimentation type solid-liquid separation apparatus,
For example, the biggest technical difference from the upflow type thickener having a feed well as shown in FIG. 4 lies in the method and position of blowing the slurry into the sedimentation tank 1.
In the conventional apparatus as shown in FIG. 4, the slurry supplied into the feedwell is essentially blown downward, although there are some ideas. The flocs (solid components) in the blown-out slurry initially settle down by gravity and then spread as described later. On the other hand, the liquid is a mixed-phase flow with the flocs and becomes one downward flow, but it changes direction from horizontal flow to upward flow and is discharged from the upper part of the tank. Therefore, when the slurry is continuously supplied, the flocs that settle merge with the liquid that becomes a horizontal flow → upflow, interfere with each other, and form a laterally widening flow. And the supplied slurry density is larger than the liquid phase,
Since it is smaller than the concentrated slurry layer, the slurry spreads over the entire upper surface of the concentrated slurry layer in the tank, and is separated by interfering sedimentation. On the other hand, in the case of horizontal blowing by the device of the present invention, the flocs settle down downward due to gravity, whereas the liquid turns from a horizontal flow to an upward flow, so the flocs do not encounter an upward flow of liquid. That is, since the particles fall and settle at a free sedimentation speed without passing through the interference zone, the separation speed becomes extremely high. In addition, even if the slurry supply port is arranged in the vicinity of the concentrated slurry layer by making the blowout substantially horizontal, the concentrated slurry layer 18 and the slurry blowing member are rarely caused by the blowing up of the concentrated slurry. Since the positions of 3 can be close to each other, as a result, the fall distance of the flock can be shortened, and the separation time can be further shortened.

Since the concentrated slurry layer 18 shown in FIG. 1 is formed in the tapered portion 1b having a predetermined taper angle θ, the concentrated slurry layer 18 has a thickness (depth) relative to its volume. It becomes large and is compressed well by its own weight, and the degree of concentration or deliquoring increases. Moreover, since the rake 10 gently agitates, the concentration of the concentrated slurry layer 18 becomes very high. Further, although a clarified layer is formed on the upper part of the settling / separation tank 1, the settling rate of the solid component is high and the settling property is good, as described above, so the solid component content in the clarified liquid is extremely small. Become. That is, since a concentrated slurry having a high degree of concentration can be obtained and a clear liquid having a very small solid component content can be obtained, the solid-liquid separation rate of the thickener T1 becomes extremely high. In the example shown in FIG. 1, the slurry blowing member 3 having a horizontal blowing direction and a radially outward direction.
The are provided, as shown, without this manner in FIG. 9, for example, slightly relatively close positions on the interface L ₁ above the surface L ₁ of the thickened slurry layer 18, delivery direction is horizontal Further, for example, a ring-shaped slurry blowout member that faces inward in the radial direction may be provided. The expression of the angle at which the slurry is blown out from the slurry blower member 3 of the present invention in a substantially horizontal direction indicates a range in which the solid components that settle do not substantially form an interference settling zone, but settle naturally. According to the results of experiments conducted by the present inventor, the range from the completely horizontal direction to the interface L _{1 in the} upward or downward direction is within about 30 °, preferably within about 15 °, more preferably within about 10 °. If this is the case, the above purpose can be satisfied to a higher degree.

FIG. 2 exemplifies a thickener with a pressure specification. The device of the present invention exhibits the same effect at both normal pressure and pressure. In order to avoid duplication of description, the same members as those of the thickener T1 of the normal pressure specification shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted. Only the points different from the thickener T1 of the normal pressure specification will be described. As shown in FIG. 2, in the thickener T2 of the pressure specification, the upper part of the settling separation tank 1 is the lid part 1c.
It is closed and has a closed structure. The overflow gutter 4 ′ is attached to the inner peripheral surface of the straight barrel portion 1 a inside the sedimentation separation tank 1. Therefore, Thickener T2
Can perform solid-liquid separation while maintaining the pressure in the sedimentation separation tank 1.

Further, in the thickener T2 of the pressurizing specification, since the settling / separating tank 1 has a closed structure, the overflow gutter 4'and the clear liquid discharge passage 5 are replaced by a ring shape as shown by phantom lines. It is also possible to dispose the clarified liquid discharge passage 19 above the settling separation tank 1 to separate the clarified liquid.

The thickeners T1 and T2 according to the present invention will be described below.
In the case of using, one design standard obtained by the experiment or analysis of the present inventor will be illustrated. As shown in FIG. 3, the specifications related to the basic design are tank diameter D, straight body part height H,
Taper angle θ, concentration of original slurry Cs, concentration of concentrated slurry Cx (concentration of under slurry Cx), rising velocity u _{1 of} liquid in the tank, linear velocity of slurry blowing from slurry blowing member 3, u ₂ , slurry blowing member 3
And the distance L between the concentrated slurry layer interface L ₁ and the residence time t of the solid component. The specific numerical values shown below vary depending on the target slurry type, slurry concentration, used flocculant, discharged slurry concentration, separation efficiency, etc., and are not unique. Therefore, it is recommended to confirm the optimum value by a simple preliminary experiment when designing.

The tank diameter D is 1 m and the straight body height H is 0.2 D
In the sedimentation / separation tank 1 having 1.0 D and a taper angle θ of 60 ° to 120 °, the original slurry concentration Cs was 30 g / l to 100 g / l.
(40 g / l to 60 g / l), the particle sedimentation speed (interfacial sedimentation speed obtained by adding a flocculant to the slurry having the original slurry concentration and stirring the mixture) was 15 to 100 m / hr (40 m / hr to 80 m / h
r), the distance h between the slurry blowing member 3 and the concentrated slurry layer interface L ₁ is 5 cm to 50 cm, preferably 10 cm to 3
0 cm, the slurry blowing linear velocity u ₂ from the slurry blowing member 3 is 50
cm / sec or less (usually 10 cm / sec to 50 cm / sec), the rising velocity u _{1 of the} liquid in the tank is 10 m / hr to 30 m / hr, preferably 15
By setting m / hr to 25 m / hr, the residence time of the slurry discharged from the slurry blowing member 3 in the sedimentation separation tank 1 is within 10 minutes, preferably within 5 minutes from the concentrated slurry discharge passage 6. Concentrated slurry concentration Cx is 350 g / l or more (usually 400 g / l to 600 g / l), and separation efficiency is 9
It can be separated at 8% or more. In the sedimentation separation tank 1, the original slurry concentration Cs is 100 g / l to 300 g.
/ L (100g / l ~ 150g / l), particle settling speed is 0.5m
/ Hr-15m / hr (3m / hr-15m / hr) original slurry,
The distance h between the slurry blowing member 3 and the concentrated slurry layer interface L ₁ is 5 cm to 50 cm, preferably 10 cm to 30 cm, and the slurry blowing linear velocity u ₂ from the slurry blowing member 3 is 50 cm / sec or less (usually 10 cm / sec. ~ 50 cm / sec), and the rising flow rate u _{1 of the} liquid in the tank is set to 3 m / hr to 15 m / hr, preferably 4 m / hr to 12 m / hr, to settle and separate the slurry discharged from the slurry blowing member 3. When the residence time in the tank 1 is within 10 minutes, the concentrated slurry concentration Cx from the concentrated slurry discharge passage 6 is 35
Separation is possible at 0 g / l or more (usually 400 g / l to 600 g / l) and a separation efficiency of 98% or more. The conditions for adding the flocculant added to the slurry supply passage are as follows: by the time the slurry is blown out from the slurry outlet, the solid components in the slurry and the flocculant are mixed in the slurry to produce flocs. It is preferable to select an addition position at which a residence time necessary for sufficient growth is obtained and a flow strength at which flocs generated in the slurry are not broken. The conditions are not unique depending on the target slurry for solid-liquid separation (solid physical properties, liquid physical properties, slurry concentration, temperature), the type of coagulant, the amount added, etc., but the target is, for example, the aluminum hydroxide production process by the Bayer method. In the solid-liquid separation of the red mud and the solution, the sodium polyacrylate-based coagulant is added in an amount of 0.005% to 0.1% by weight based on the weight of the solid in the slurry, and the flow rate of the slurry supply passage is about 1 m / m. By setting the residence time of the coagulant from the addition of the coagulant to the outlet of the slurry to about 3 seconds or more, usually about 5 seconds to about 60 seconds under the condition of seconds to about 4 m / sec, the slurry temperature When the slurry concentration is 120 ° C to 140 ° C and the slurry concentration is 30 g / l to less than 100 g / l, the sedimentation velocity of flocs (solid particles) blown out from the slurry outlet is 15 m.
/ Hr-100m / hr, slurry temperature 70 ℃ -100 ℃
When the slurry concentration is 100 g / l to 300 g / l, 0.
Very fast solid-liquid separations of the order of 5 m / hr to 15 m / hr can be achieved. As described above, according to the device of the present invention, the residence time of the solid component can be significantly shortened and the device can be downsized while ensuring a very high solid separation rate.

[0034]

According to the apparatus of the present invention described in detail above, since the slurry is blown out from the slurry blowing member into the settling separation tank in a substantially horizontal direction, almost no liquid flows below the slurry blowing member. Does not occur. For this reason, the solid components in the slurry settle in a state close to free settling, and the time required for settling is shortened. Therefore, the residence time of the solid component is significantly shortened, and the device can be downsized. In addition, when the slurry blowing member is arranged close to the concentrated slurry layer interface,
The time required for the solid components to settle is further reduced. Therefore, the residence time of the solid component is surely shortened, and the device can be downsized.

In addition to the above, when a coagulation processing means for coagulating the raw slurry by adding a coagulant is provided, and the coagulation processing means is provided in a step before the slurry supply passage,
Since the aggregating means is provided outside the solid-liquid separation device,
The solid-liquid separation device is made compact.

In addition to the above, when a slow stirring means for slowly stirring the concentrated slurry layer formed in the lower part of the sedimentation separation tank is provided in the sedimentation separation tank, the flocculation treatment means is used for solid-liquid separation. Since the solid-liquid separation device is provided outside the device, the solid-liquid separation device can be made compact, and the liquid removal effect of the concentrated slurry layer can be improved, so that the solid-liquid separation device can be made more compact.

[0037]

EXAMPLES The present invention will now be described in more detail with reference to Examples. Example 1 A sedimentation separation tank having a structure shown in FIG. 1 (tank diameter D; 100 cm, straight body part height H; 70 cm, taper angle θ; 60 °, separation distance h between slurry outlet member 3 and concentrated slurry layer interface L ₁ 25 cm, rake speed; 3.6 rpm, temperature 80 ° C derived from the melting step of the buyer step in the thickener, slurry concentration 5
A slurry of 18.5 m ³ / hr in which a sodium polyacrylate-based polymer coagulant was added to a slurry of 0 g / l in an amount of 0.015 g / l was used in a horizontal direction from the slurry discharging member 3 at a slurry discharge linear velocity of 23 cm / sec.
It is blown into the sedimentation separation tank (parallel to the concentrated slurry layer interface L ₁ ), the concentrated slurry having a slurry concentration of 366 g / l is discharged from the concentrated slurry discharge passage 6, and the solid content concentration of the overflow gutter is 0.14 g / l.
l of clarified liquid was discharged. In this experiment, the residence time of the slurry discharged from the slurry blowing member 3 in the settling separation tank 1 is 3 minutes, and the rising velocity of the liquid in the tank and the particle settling velocity are 2
It was 0 m / hr and the solid-liquid separation efficiency was 99.8%.

Comparative Example 1 Using the thickener having the structure shown in FIG. 1, the blowing direction was set to 45 ° above the horizontal, and the same amount of slurry as used in Example 1 was supplied. At this time, the concentration of the slurry discharged from the concentrated slurry discharge passage was 300 g / l, the solid content concentration of the clarified liquid discharged from the overflow gutter was 8 g / l, and the separation efficiency was 86%. In addition, the thickener having the structure shown in FIG.
The same amount of slurry as that used in (1) was supplied. At this time, the concentration of the slurry discharged from the concentrated slurry discharge passage is 320
g / l, the solid content of the clarified liquid discharged from the overflow gutter was 5 g / l, and the separation efficiency was 91%.

Comparative Example 2 As a solid-liquid separation tank, a tank diameter D having a shape shown in FIG. 4; 100 cm,
Using a thickener having a structure having a cylindrical feedwell having a diameter of 20 cmφ and a height of 30 cm in a tank having a straight body height H of 70 cm and a taper angle θ of 60 ° (the stirring conditions are the same as in Example 1), The same flocculant was added to the same slurry as that used in Example 1, and the same amount was supplied. At this time, the turbulence in the tank is large,
The interface of the concentrated slurry layer was not confirmed, the slurry concentration discharged from the concentrated slurry discharge passage was 280 g / l, the solid content concentration of the clarified liquid discharged from the overflow gutter was 19 g / l, and the separation efficiency was 71. It was 6%.

Comparative Example 3 The height of the feed well shown in Comparative Example 2 was 50 cm,
The same amount of slurry as that used in Example 1 was supplied. At this time, the concentration of the slurry discharged from the concentrated slurry discharge passage was 330 g / l, the solid content concentration of the clarified liquid discharged from the overflow gutter was 3 g / l, and the separation efficiency was 95%.

[Brief description of drawings]

FIG. 1 is an elevation view of a partial cross-section of a thickener of normal pressure specifications according to the present invention.

FIG. 2 is an elevational view of a partial cross section of a thickener of a pressure specification according to the present invention.

FIG. 3 is a schematic diagram showing specifications of basic design items of the thickener according to the present invention.

FIG. 4 is a schematic view of a conventional upflow thickener.

FIG. 5 is a schematic view of a conventional horizontal type coagulating sedimentation apparatus.

FIG. 6 is a schematic view of a conventional slurry blanket type coagulating sedimentation apparatus.

FIG. 7 is a schematic view of a conventional slurry circulation type coagulating sedimentation apparatus.

FIG. 8 is a schematic view of a conventional external circulation type coagulating sedimentation apparatus.

FIG. 9 is a partially sectional elevational explanatory view of another thickener using atmospheric pressure according to the present invention.

[Explanation of symbols]

 T1 ... Thickener for normal pressure T2 ... Thickener for pressurization 1 ... Sedimentation / separation tank 1a ... Straight body portion 1b ... Tapered portion 1c ... Lid portion 2 ... Slurry supply passage 3, 3 '... Slurry blowing member 4, 4' ... Overflow gutter 5 ... Clarified liquid discharge passage 6 ... Concentrated slurry discharge passage 10 ... Rake 11 ... Blade 15 ... Line mixer 16 ... Flocculant supply pipe 17, 17 '... Slurry outlet 18 ... Concentrated slurry layer

Claims (6)

[Claims] 1. A settling / separating tank for causing an upward total flow of a liquid component in the slurry while settling a solid component in the slurry by gravity, and a raw slurry supplied through a slurry supply passage in the settling / separating tank. A slurry blowing member for blowing out in a substantially horizontal direction, a clarified liquid discharging means for discharging the clarified liquid from the upper part of the sedimentation separation tank, and a concentrated slurry discharging means for discharging the concentrated slurry from the lower part of the sedimentation separation tank are provided. Settling type solid-liquid separator. 2. The settling type solid-liquid separation device according to claim 1, wherein a straight body portion and an upwardly widening tapered portion adjacent to a lower side of the straight body portion are formed in the settling separation tank, and a slurry blowout is performed. A sedimentation-type solid-liquid separation device, wherein the member is arranged near the interface of the concentrated slurry layer formed in the solid-liquid separation tank. 3. The settling type solid-liquid separation device according to claim 1, wherein a straight body portion and an upwardly widening taper portion adjacent to a lower side of the straight body portion are formed in the settling separation tank, and a slurry blowout is performed. The member is arranged in the vicinity of the interface of the concentrated slurry layer formed in the solid-liquid separation tank, and is arranged at a position around the center of the sedimentation separation tank in the horizontal direction. A sedimentation-type solid-liquid separation device, characterized in that the outlet is opened radially outward (outward from the center) of the sedimentation separation tank. 4. The settling type solid-liquid separation device according to claim 1, wherein the settling separation tank is provided with a straight body part and an upwardly widening taper part adjacent to the lower side of the straight body part, and a slurry blowout is provided. The member is disposed in the vicinity of the interface of the concentrated slurry layer formed in the solid-liquid separation tank, and in the horizontal direction in the vicinity of the inner wall of the settling separation tank, and the slurry outlet of the member for discharging the slurry. The sedimentation-type solid-liquid separation device is characterized in that is opened inward (toward the center) of the sedimentation separation tank. 5. The sedimentation-type solid-liquid separation device according to claim 1, further comprising an aggregating means for aggregating the raw slurry by adding an aggregating agent, and the aggregating treatment. A settling type solid-liquid separation device, characterized in that the means is provided in a step before the slurry supply passage. 6. The sedimentation-type solid-liquid separation device according to claim 1, further comprising an aggregating treatment means for adding an aggregating agent to agglomerate the raw slurry. The means is provided in a step before the slurry supply passage, and a slow stirring means for slowly stirring the concentrated slurry layer formed in the lower part of the sedimentation separation tank is provided in the sedimentation separation tank. Sedimentation type solid-liquid separator.