JPH05317900A - Continuous recovery method for fine silica sand or the like contained in slurry and device therefor - Google Patents

Abstract

PURPOSE:To enable the efficient and continuous recovery of fine silica sand, etc., by adding a flocculating agent and pulp fibers to the slurry generated in a glass polishing stage, etc., and separating the fine silica sand, etc. CONSTITUTION:The flocculating agent is added to the slurry of a low concn. (about 0.5 to 5%) contg. the fine silica sand, etc., to settle the slurry in a settling chamber 1. The settled component of the slurry is taken out and the pulp fibers are added to the taken out slurry in a first mixing and stirring device 5 to flocculate the fine silica sand, etc. The flocculating agent is added to the flocks of the fine silica sand, etc., to accelerate the flocculation of the fine silica sand, etc., in a second mixing and stirring device 12. The slurry is separated to the water and the flocs using a sieving surface device 15. The flocs are heated in a steam heater 18. The flocks in a heated state are compressed to squeeze out the water in a compressing device 17. As a result, the fine silica sand, etc., are efficiently and continuously recovered from the slurry.

Description

Detailed Description of the Invention

[0001]

[Industrial field of application] The present invention is intended to promote the effective use of industrial waste, and is carried out when separating and collecting inorganic fine particles such as fine silica sand contained in wastewater generated in a glass polishing process or the like. The present invention relates to a continuous recovery method for fine sand and the like and an apparatus therefor.

[0002]

2. Description of the Related Art Sand water containing fine silica (concentration: 0.5 to 5%) is generated during the glass polishing process, but the water content of 20 to 20% is required to collect and use or dispose of the fine silica in this sand water. Three
It is necessary to set it to 5% (here,% is a weight ratio, and the same applies to all other same labels).

As a conventional method for realizing this, for example, a) water is removed from sand water by a centrifuge to increase its concentration, and then this is introduced into a filter press to squeeze out water. B) introducing sand water into a sedimentation basin, where fine silica sand is allowed to settle and agglomerate, and after removing the supernatant liquid, a process in which the sediment is dried in the sun is repeated, and so on.

[0004]

The above-mentioned conventional method has the following problems. That is, in the former method, since the slurry is processed in a centrifuge, the dewatering efficiency is poor and the energy cost is high, and in the dewatering process by the filter press, an extremely large amount of fine sand is mixed into the drainage. It requires a time-consuming treatment to discharge it to the outside world. On the other hand, the latter method requires a very large sedimentation tank in order to increase the processing capacity because it is a batch treatment with sedimentation tank, and because it is sun-dried, it depends on the weather and the sedimentation portion is dried. When it comes, the surface layer will be scattered by the wind and cause pollution. It is an object of the present invention to provide a novel method and device for recovering fine silica sand in order to solve these problems of the conventional means.

[0005]

In order to achieve the above object, in the present invention, the following processes are continuously carried out in the order described. That is, (1) a low-concentration slurry (0.5 to 5%) containing fine silica sand or the like generated in a glass polishing step or the like is introduced into a settling tank, and the fine silica sand or the like is sedimented and concentrated. At this time, the coagulant PA
C (trademark) or its equivalent is added,
The amount added is about 1.0 to 3.0%. By this treatment, the concentration of the sediment of the slurry retained at the bottom of the settling tank is about 12 to 30%. (2) The slurry obtained by the sedimentation and concentration is taken out into a mixing and stirring device, and pulp fibers are added thereto. The addition amount of this pulp fiber is set to about 0.5 to 4.0% in consideration of the processing smoothness of the slurry. As a result of this treatment, flocs having fine silica particles adhered to the pulp fibers are formed in the slurry, and the presence of the flocculant PAC or its equivalent promotes the adhesion of fine silica particles to the pulp fibers. Will be things. (3) The slurry or the like is also introduced into the mixing and stirring device, and the coagulant NP-800 (trademark) or its equivalent is added. This addition amount is about 0.001 to 0.1%. By this treatment, fine sand or the like is more effectively attached to the flocs. (4) The slurry and the like are separated into water and flocs by a sieving surface device. The fine silica sand and the like are flocced and adhered to the pulp fibers, and the pulp fibers function as a filter and are filtered, so that they are effectively prevented from being mixed into the separated water. (5) The separated flocs are heated by a heating device.
The heating temperature at this time is about 60 to 80 ° C. This improves the dehydration effect of flocs. (6) The heated flocs are squeezed by a squeezing device to squeeze out water to obtain a cake containing fine silica sand and the like having a water content of 25 to 28%. Also in this case, fine silica sand and the like are effectively flocculated and adhered to the pulp fibers, and filtered by the pulp fibers functioning as a filter, so that they are effectively prevented from being mixed with water. (7) If necessary, the cake is dried with a dryer.

[0006]

An embodiment of the present invention will be described with reference to the drawings. In the figure, 1 is a settling layer for precipitating solids in a slurry, and a stirring blade 3 rotated around a shaft 2 by a motor or the like is provided in a container 1a. It consists of blades 3b fixed to the outer peripheral surface, and the slurry supplied from the upper opening of the cylinder 3a reaches the bottom of the container 1a through the inside of the cylinder 3a.
It is supposed that the inside of the container 1 rises and overflows from the upper edge thereof, and the overflowed water is discharged to the outside through the groove 4 provided along the outer upper edge of the container 1a. In this example, the container 1a
Has a capacity of 2 m ³ .

Reference numeral 5 is a first mixing and stirring device for dispersing and mixing pulp fibers into the slurry taken out from the bottom of the settling tank 1, and a rotating shaft 7 driven by a motor 6 or the like in the cylindrical body 5a.
In addition, the rotary shaft 7 is provided with a large number of stirring blades 8 having a spiral surface, a supply port p1 is provided at the upper end of the tubular body 5a, and a discharge port p2 is provided at the lower end of the tubular body 5a. The slurry and pulp fibers supplied from the supply port p1 are agitated by the rotation of the rotating shaft 7, and the discharge port p is provided.
It is supposed to be transferred to 2.

Reference numeral 9 is a stirring blade 1 rotated by a motor 10 or the like.
The storage tank 1 is provided to temporarily store the slurry or the like stirred by the mixing and stirring device 5. This storage tank is not essential and may be provided as needed.

Reference numeral 12 is a second mixing and stirring device for adding the coagulant NP-800 or its equivalent to the slurry stirred by the stirring device 5, and a screw blade rotated by a motor 13 or the like in the cylindrical body 12a. 14 is provided, and the supply port p is provided at the upper part of the starting end side of the cylindrical body 12a as in the agitator 5.
3 is provided, and the discharge port p4 is provided at the lower end of the cylindrical body 12a.
Is provided, and the slurry or the like supplied from the supply port p3 is transferred toward the discharge port p4 by the rotation of the screw blades 14. In this example, the capacity of the cylindrical body 12a is 1 m ³
Is set to.

Reference numeral 15 is a sieving surface device for separating and collecting flocs from the slurry or the like taken out from the agitating device 12. Specifically, it is a rotary screen having a cylindrical sieving surface 15a rotated by a motor 16 or the like. is there.
In this example, the diameter of the cylindrical sieving surface 15a is 300 mm, the length is 1 m, and the mesh size is fine (1 mm).

Reference numeral 17 is a squeezing device for squeezing water out of the flocs taken out from the sieving surface device 15 to obtain a cake, and this device is provided with a heating device 18 for heating the flocs supplied thereto. ..

In this embodiment, a screw press is used as the squeezing device 17, and specifically, a cylindrical filter 19 fixedly installed and a screw fixed with screw blades and rotated by a motor 20 or the like. A drum 21 is provided, a supply port p5 is provided at an upper portion on the starting end side of the tubular filter 19, and a discharge port p6 is provided at a lower end portion of the filter 19, so that the sieving surface device 15 supplies the supply port p5
The flocs supplied via the screw drum 21 are transferred to the discharge port p6 by the rotation of the screw drum 21, and in this process, the screw drum 21 and the cylindrical filter 19 are squeezed to discharge the moisture from the cylindrical filter surface. It is made into a cake and discharged from the discharge port p6. In this example, the cylindrical filter 19 has a diameter of 200 m.
m, and the length is 1.5 m.

The heating device 18 is a screw press 17
It is supposed that the flocs supplied to the are heated with steam. In this case, the heating device 18 may be configured as an independent structure and may be located in the front stage of the screw press 17.

22 and 23 are slurry pumps 22a and 2
A transfer pipe means provided with 3a, the former for transferring the slurry settled at the bottom of the settling tank 1 to the mixing and stirring device 5, and the latter for transferring the slurry and pulp fiber from the mixing and stirring device 5 to the storage tank 9. It is for doing. Reference numeral 24 is a transfer pipe means provided with a constant transfer type slurry pump 24a for transferring from the storage tank 9 to the mixing and stirring tank 12.

Reference numeral 25 is a funnel for receiving the moisture that has passed through the tubular sieving surface 15a, and 26 is a funnel for receiving the moisture that has passed through the tubular filter. Further, 27 is a belt type transfer means for transferring the cake discharged from the screw press 17 to another place such as a dryer room.

An example of use of the device of the present invention constructed as described above and its operation will be described. Slurry (sand water), which is the wastewater generated from the glass polishing step and contains approximately 0.5 to 5% fine sand, is continuously supplied to the upper opening of the cylindrical body 3a of the precipitation tank 1 at an appropriate flow rate. On the other hand, the coagulant PAC is also continuously added from the upper opening of the cylindrical body 3a so that its concentration in the container 1a is 1.0 to 3.0%. The flow rate of the slurry is adjusted so that the residence time in the container 1a is approximately 60 to 90 minutes, and the aggregating agent PAC is evenly dispersed in the container by the slowly rotating stirring blades 3. The action of the flocculant PAC causes the fine sand to effectively settle. For this reason container 1
The supernatant liquid that rose in a has a concentration of fine silica sand of 500 p
It becomes pm or less and is discharged from the upper edge of the container 1a to the outside. On the other hand, the slurry settled on the bottom of the container 1a is concentrated to about 12 to 30%.

The concentrated slurry is continuously transferred into the first mixing / stirring device 5 and, at the same time, pulp fibers are continuously supplied from the supply port p1 of the device 5 at a constant flow rate. Done As a result, from the discharge port p2 of the same device 5, a slurry containing about 0.5 to 2.0% of pulp fibers and the like is discharged while being mixed and stirred.

The slurry and the like are once transferred to the storage tank 9. The storage tank 9 functions so as to absorb the difference between the processing capacity of the preceding step and the processing capacity of the subsequent step.

The slurry or the like temporarily stored in the storage tank 9 is quantitatively supplied to the second mixing and stirring device 12 by the slurry pump 24a, and at the same time, the flocculating agent NP80 is supplied.
0 is continuously supplied from the supply port p3 of the device 12. As a result, the slurry or the like in the apparatus 12 is well agitated with 0.01 to 0.1% of the coagulant NP800 added. Then, in the apparatus 12, the interaction between the slurry, the coagulant, and the pulp fibers present therein causes the fine silica sand to efficiently adhere to the pulp fibers, thereby promoting the flocculation thereof.

The slurry or the like in this state is transferred to the sieving surface device 15, where water is separated by the cylindrical sieving surface 15a. At this time, since the fine silica sand adheres to the pulp fibers to form flocs and the pulp fibers function as a filter for the fine silica sand, it is effective that the wastewater passing through the cylindrical sieving surface 15a is mixed with the fine silica sand. Is prevented. As a result, the concentration of fine sand and the like contained in this wastewater is reduced to approximately 3000 ppm or less. Then, the flocs remaining on the surface of the cylindrical sieving surface 15a are discharged to the outside of the apparatus, and the water having passed through the sieving surface 15a is returned to the precipitation tank 1. In this case, the concentration of fine silica on the floc side is 30 to 45%.

After this, the flocs are fed to the screw press 17, where the heating device 18 vaporizes them for 60-80%.
It is squeezed by the screw drum 21 while being heated to ℃ to squeeze out water. At this time, the concentration of fine silica is 30 to 4
If the slurry is a 5% slurry and no pulp fiber is added, it is inevitable that a large amount of fine sand is mixed in the drainage when dehydrated by a screw press, but in the present invention, it is described above. As described above, since fine silica sand is adhered to pulp fibers to form flocs and pulp fibers function as a filter for fine silica sand, even if dehydrated by a screw press, the waste water passing through the cylindrical sieving surface 15a does not become fine. The mixture of silica sand is effectively prevented. As a result, a cake having a water content of 25 to 28% is formed inside the tubular filter 19 and the discharge port p6
On the other hand, the squeezed waste water is returned to the settling tank 1 after passing through the cylindrical filter surface.
The concentration of fine silica in the wastewater at this time is also 3000 ppm.
It becomes the following.

The cake thus obtained is a mixture of pulp fibers and fine silica sand and has a low water content. Therefore, by adding the cement or asbestos to the cake as it is, the cake-making material It can be used as a pile or wall material. That is, fine silica sand, which has been an industrial waste that has been expensive to dispose of, can be used very effectively.

It is also possible to transfer this cake to a dryer room and dry it indoors for various purposes.

Applicants have a throughput of 100k with the present invention.
As a result of testing in a g / H test plant, it was confirmed that the running cost was significantly reduced as compared with the conventional method using a centrifuge and a filter press.

[0025]

According to the present invention having the above construction,
Compared with the conventional method using a centrifuge and a filter press, the following advantages can be obtained, that is, because a centrifuge is not used, it is possible to obtain a fine sand mixture having a certain water content or less at a low energy cost. In addition, because the fine silica sand is flocculated by adhering to the pulp fiber and the pulp fiber functions as a filter for the fine sand during the separation of water, the fine sand is finely dispersed in the water separated from the slurry. It is possible to effectively prevent the mixing of silica sand, and this makes it possible to discharge the separated water as it is or to the outside after simple treatment.

Further, the following advantages can be obtained as compared with the conventional method of performing sun-drying after settling by a settling tank: that is, a slurry is continuously processed instead of batch processing, so that a small settling tank is used. Even if it is, etc., it will be able to exert a large processing capacity, and since it is not sun dried, it will not be affected by the weather and the dried fine sand will not be scattered by the wind. Of.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

[Explanation of symbols]

 1 Precipitated Layer 5 First Mixing Stirrer 12 Second Mixing Stirrer 15 Sieve Surface Device (Rotary Screen) 18 Heating Device 17 Squeezing Device (Screw Press)

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location C02F 11/12 C 7824-4D 11/18 7824-4D

Claims (5)

[Claims] 1. When recovering fine silica sand or the like from a low-concentration (approximately 0.5 to 5%) slurry containing fine silica or the like generated in a glass polishing step, (1) a flocculant PAC or The equivalent of this is added to settle the slurry, (2) the settled portion of the slurry is taken out, and pulp fiber is added to this to flocculate fine silica sand, etc. (3) Coagulant NP-800 Alternatively, an equivalent product thereof is added to promote the formation of flocs such as fine sand, (4) Separation of the slurry thus formed into water and flocs, (5) Heating of the separated flocs, (6) Slurry characterized by squeezing the heated flocs to squeeze out water to obtain a cake containing fine silica sand and the like in this order and continuously. Continuous recovery methods such as fine silica sand. 2. A settling layer for precipitating fine silica sand or the like from a low concentration (0.5 to 5%) slurry containing fine silica sand or the like produced in a glass polishing step or the like, taken out from the bottom of the settling tank. A first mixing / stirring device for dispersing and mixing pulp fibers into the slurry; a second mixing / stirring device for adding the flocculant NP-800 or an equivalent thereof to the slurry taken out from the first stirring device; (2) A sieving surface device for separating flocs from the slurry and the like taken out from the mixing and stirring device, a heating device for heating the flocs taken out from the sieving surface device, a cake obtained by squeezing out water from the flock heated by the heating device. A continuous recovery device for fine sand and the like contained in the slurry, characterized in that a compression device for obtaining is obtained in this order. 3. The continuous recovery apparatus for fine silica sand contained in the slurry according to claim 2, further comprising a dryer for drying the cake after the screw press. 4. The continuous recovery device for fine sand contained in the slurry according to claim 2, wherein the sieving surface device is a rotary screen. 5. The heating device is a steam heating device and the squeezing device is a screw press, and the steam heating device is attached to the screw press, such as fine sand contained in the slurry. Continuous recovery device.