JP2007083157A - Agitation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an agitation apparatus in which fluids can easily be mixed homogeneously and from which a mixed fluid can be discharged promptly without being retained in a tank as long as possible when discharged. <P>SOLUTION: The agitation apparatus 100 for agitating the fluid having 20-60 mPa-sec maximum viscosity at 25°C is provided with: the tank 10; an agitation blade 5; and a bottom discharge port 3. The agitation blade 5 is fit to a rotary shaft 4 hung from the outside of the tank toward the center of the tank 10. The angle θ formed by an extension line of the rotary shaft 4 and an extension line of the lower inclined surface 2 of the tank 10 is 10-55°, preferably, 15-50°. The agitation blade 5 preferably comprises an anchor blade at the least. The clearance (a) between the anchor blade 5 and the internal wall surface 1 of the tank 10 is preferably 1-50 mm and that between the anchor blade 5 and the internal bottom surface of the tank 10 is preferably 1-50 mm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fluid stirring device, and more particularly, to a stirring device for mixing and stirring a viscous fluid having a maximum viscosity at 25 ° C. of about 20 to about 60 millipascal seconds.

  In the chemical industry, agitation of various fluids is generally provided with a straight body having a cylindrical wall surface, a tank connected to the lower end thereof, and a lower part having a bottom surface with a semi-elliptical longitudinal section. This is carried out by a stirring device in which a stirring blade is provided on a rotating shaft arranged rotatably from the outside.

  Various types of agitating blades suitable for the state and physical properties of the fluid to be mixed are suitably used.

  By the way, in general, fluids can be broadly classified into Newtonian fluids in which Newton's viscosity law is established and non-Newtonian fluids in which Newton's viscosity law is not satisfied. Non-Newtonian fluids can be further classified into several fluids, for example, sub-plastic fluids (structural viscosity), dilatant (dilatancy), bingham, non-bingham. Since these non-Newtonian fluids have different behaviors due to the difference in shear stress caused by the difference in stirring speed, it is important to select the shape, size, and position of the stirring blade to be used. In particular, in Bingham and non-Bingham, which have a yield value peculiar to fluids, since they flow only when a shear stress higher than the yield value is given, in order to improve the discharge performance of the tank, a stirring blade In addition to the shape of the tank, the shape of the tank is also important.

  Among various fluids, in particular, it is a conventional problem to uniformly stir a fluid with strong adhesion and poor fluidity without adhering to the inner wall of the tank. As a means for solving this problem, for example, a patent Reference 1 is cited.

  In patent document 1, the conventional stirring blade is considered from a viewpoint of stirring a liquid with high viscosity and strong adhesiveness.

  Paddle blades have poor discharge performance, and when used for liquids with high viscosity, only the blades are agitated and the liquid on the inner wall of the tank does not move. In addition, the anchor blades stir the liquid at the bottom of the tank and the inner wall well, but the upper and lower mixing is poor. In particular, in a high-viscosity liquid, the blades and the liquid rotate together, which may reduce the stirring action. On the other hand, of the turbine blades, the flat blades are excellent in shearing properties, but the discharge performance is not good, while the inclined blades are in the opposite tendency, that is, the discharge performance is excellent, but the shearing properties are not good. Ribbon blades are suitable for relatively high-viscosity liquids, but have the disadvantage that the structure is complex and the manufacturing costs are high and expensive.

  Therefore, the advent of an agitation tank that can perform uniform agitation by mixing the liquid with high viscosity in the horizontal and vertical directions without adhering to the inner wall of the tank is desired, and the anchor blade, baffle plate, paddle blade By combining the two, a uniform mixing was obtained by a combination of planar overall mixing with anchor wings and baffle plates and vertical mixing with paddle wings.

JP-A-5-212261

  However, in the prior art, although uniform stirring is achieved, there is a concern that when the liquid is supplied to the next process, the back of the baffle plate often adheres and the entire amount cannot be discharged from the stirring tank, leading to a decrease in productivity. was there. In particular, when continuous production is performed, there is also a concern that the remaining liquid stays in the tank for a long time, and the quality is impaired. In addition, when a constant supply to the next process is required, if the amount of liquid to be supplied is reduced, if there is a clearance from the tip of the stirring blade to the bottom of the stirring tank, the flow in the direction of gravity becomes weak and quantitative. There was a problem that quality could be lost due to inability to supply.

  The present invention provides a stirring device that can uniformly stir and mix a fluid and can quickly discharge the fluid obtained by stirring and mixing without causing the fluid to stay in the tank as much as possible.

  In order to achieve the above object, the present invention is a stirring device comprising a tank, a stirring blade, and a bottom discharge port, and has a maximum viscosity at 25 ° C. of 20 to 60 millipascal seconds. The fluid is agitated.

  In the stirring apparatus, the stirring blade is disposed on a rotating shaft that hangs down from the outside of the tank at the center of the tank, and an angle formed by an extended line of the rotating shaft and an extended line of the lower inclined surface of the tank is 10 ° to 55 °. It is preferable that

  In the stirring device, the stirring blade preferably includes at least an anchor blade that scrapes off the fluid near the bottom surface and the fluid near the wall surface inside the tank.

  In the agitation apparatus, the clearance between the anchor blade and the wall surface inside the tank is preferably 1 to 50 mm, and the clearance between the anchor blade and the bottom surface inside the tank is preferably 1 to 50 mm.

  According to the present invention, at the time of stirring, it is possible to easily perform uniform mixing without using a member such as a baffle that hinders the discharge of fluid as much as possible. It becomes possible to discharge quickly without stagnation as much as possible in the tank.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a longitudinal sectional view showing an outline of a configuration of a fluid stirring apparatus 100 according to an embodiment of the present invention. The stirring device 100 includes a tank 10, a bottom discharge port 3, and a stirring blade 5. The tank 10 has a cylindrical wall surface 1 and a conical lower inclined surface 2 connected from the lower end thereof. The bottom discharge port 3 is provided at the conical apex portion of the lower inclined surface 2. The stirring blade 5 includes a rotating shaft 4 disposed from the outside of the tank at the center of the tank 10 and is rotatably provided.

  In the embodiment of the present invention, the angle θ formed by the extension line x of the rotating shaft 4 and the extension line m of the lower inclined surface 2 is preferably 10 to 55 °, more preferably 15 to 50 °. When θ is less than 10 °, the capacity of the tank 10 is reduced. Therefore, when the capacity is secured, the stirring tank becomes long in the vertical direction. In particular, when the size of the wall surface 1 is constant, the length of the lower inclined surface 2 becomes longer, so that the overall stirring tank is long in the vertical direction as a whole. In any case, it is not realistic to make θ less than 10 °. On the other hand, when θ exceeds 55 °, the angle of the conical lower inclined surface 2 with respect to the horizontal plane becomes gentle, so that the fluidity in the direction of gravity decreases, and the fluid does not reach the bottom discharge port 3 and is inclined downward. It stays on the surface 2 and it is not easy to discharge the whole amount.

  The stirring blade 5 may have any shape as long as the tip thereof is close to all of the wall surface 1, the lower inclined surface 2, and the bottom discharge port 3 in the tank 10 in contact with the fluid. That is, if the fluid in the vicinity of the wall surface 1 in the tank 10 and the fluid in the vicinity of the bottom surface defined by the lower inclined surface 2 and the bottom discharge port 3 are scraped and the inside of the tank 10 can be uniformly mixed and stirred, Any material may be used, but if the structure is complicated, adhesion to the stirring blade increases, so that a simple structure is preferable. For example, an anchor wing as shown in FIG. 1, which is composed of a wing made of a saddle-shaped vertical flat plate adjacent to the wall surface 1, the lower inclined surface 2 and the bottom discharge port 3, is suitable. If necessary, a paddle blade or the like that assists stirring in the depth direction of the tank 10 may be used in combination.

  The clearance between the tip of the stirring blade 5 and the inner wall of the tank is preferably 1 to 50 mm. More preferably, the clearance a between the stirring blade 5 and the wall surface 1 is 1 to 10 mm, the clearance b between the stirring blade 5 and the lower inclined surface 2 is 1 to 10 mm, and the clearance c between the stirring blade 5 and the bottom discharge port 3 is 1. -10 mm. When the clearance between the tip of the stirring blade 5 and the inner wall of the tank is less than 1 mm, the inner wall of the tank and the stirring blade come into contact with each other due to vibration during stirring, and the tank and the stirring blade may be damaged. Further, when the clearance between the tip of the stirring blade 5 and the inner wall of the tank is 50 mm or more, the stirring action in the vicinity of the inner wall of the tank is weakened, so that there is a risk of increasing the adhesion of fluid to the inner wall of the tank. There is a possibility that uniform mixing cannot be performed for the solution.

  The bottom discharge port 3 may be anything as long as it has an opening capable of discharging the fluid inside the tank 10. For example, a flush valve or a shut nozzle can be provided to control the discharge of the fluid from the tank 10. It is good.

  When the fluid of the contents is accompanied by heat generation, a jacket (not shown) may be provided around the tub 10 so that the cooling water can be passed through and cooled. At this time, if it is necessary to heat the fluid of the contents, warm water, steam, or a heat medium can be introduced into the jacket.

  The material of the agitation tank apparatus 100 in the present embodiment, in particular, the material of the portion in direct contact with the fluid, is preferably corrosion resistant stainless steel such as SUS304.

  Further, in the present embodiment, as shown in FIG. 1, when the inner diameter of the wall surface 1 of the tank 10 is B and the inner diameter of the bottom discharge port 3 is A, it is preferable that 0.1B <A <0.5B. . When A is 0.1 B or less, the inner diameter of the bottom discharge port 3 becomes narrow, resistance increases when the fluid is discharged, and smooth discharge may be hindered. On the other hand, when A is 0.5B or more, the length of the conical lower inclined surface 2 is shortened, so that the fluidity in the direction of gravity is lowered.

  FIG. 2 is a longitudinal sectional view showing an outline of a configuration of a fluid stirring apparatus 200 according to another embodiment of the present invention. The agitator 200 has substantially the same configuration as that of the agitator 100 shown in FIG. 1 except that the agitator 200 includes an agitating blade 6 composed of four inclined flat paddles.

  In the present embodiment, the bottom discharge port 3 is provided with a flash valve. Further, a stirring blade 5 that is rotated by a variable speed electric motor from the outside of the tank is provided with a vertical line hanging from the center of the tank 10 as a rotation axis 4. The variable speed electric motor used in the present embodiment can adjust the rotational speed in the range of 0 to 30 rpm. The rotating shaft 4 is also provided with a stirring blade 6 having a rotating shaft perpendicular to the rotating shaft 4, and rotates with the stirring blade 5.

  The stirring blade 5 is composed of anchor blades composed of vertical vertical plates that are continuous along the wall 10, the lower inclined surface 2, and the bottom discharge port 3 so as to scrape the vicinity of the inside of the tank 10. The width d of the blade 5 is preferably 80 mm to 100 mm. The stirring blade 6 is composed of four flat plate inclined paddles inclined at 60 ° from the vertical direction at a position above the stirring blade 5, and the width e of the stirring blade 6 is preferably 80 mm to 100 mm.

  The angle between the extension line x of the rotating shaft 4 and the extension line m of the lower inclined surface 2 is θ, the clearance between the stirring blade 5 and the wall surface 1 is a, and the clearance between the stirring blade 5 and the lower inclined surface 2 is b. The clearance between the stirring blade 5 and the bottom outlet 3 was c. The inner diameter of the bottom discharge port 3 is A, and the inner diameter of the wall surface 1 is B.

  The stirring device 200 shown in FIG. 2 is different from the example of the stirring device according to the embodiment of the present invention by using the devices in which the values of A, B, θ, a, b, and c are changed. Reference examples and comparative examples will be described below. Note that d and e are both constant at 0.1 B, for example, constant at 85 mm.

[Example 1]
A stirrer equipped with a tank made of SUS304 having A = 210 mm, B = 880 mm, θ = 30 °, and a volume of about 0.7 m ³ was used. Silica (SiO ₂ ) 20% aqueous solution (Snowtex XS (trade name), volume average particle size 4 nm, manufactured by Nissan Chemical Industries, Ltd.) 75% by weight, polyaluminum chloride aqueous solution (PAC100W (trade name), Asada Chemical Co., Ltd.) (Manufactured) 2.5 wt% and 0.02 mol / liter HNO ₃ aqueous solution 22.5 wt% were prepared so that the total charged amount was 520 kg (about 70% of the tank volume), and this was used as a sample.

  The sample was mixed and stirred by rotating a stirring blade 5 made of SUS304 at a rotational speed of 25 rpm for 20 minutes, with clearances from the inside of the tank set to be a = 10 mm, b = 10 mm, and c = 10 mm, respectively. A silica flocculation solution was prepared.

This silica agglomerated solution has the property that when the stirring is continued, the viscosity once rises and then falls, and there are many cases in which the numerical values in ordinary measurements vary. For this reason, "viscosity" as used in the present specification means that when a test sample is measured with a B-type viscometer (VISCONIC-ED type, manufactured by Tokimec Co., Ltd.) under a shear rate of 5 to 400 s ^-1 . The maximum value.

  The obtained silica aggregation solution was a fluid having a pH of 3.0, a specific gravity of 1.14, and a viscosity of 40 mPa · sec (all measured at 25 ° C.). In addition, this solution does not flow for a while even when the container is tilted, but exhibits fluidity only when the liquid surface is tilted to an extent exceeding 40 ° from the horizontal. That is, the obtained silica aggregation solution is considered to be a fluid having a specific yield value.

  The obtained silica agglomerated solution was discharged from the bottom outlet 3 while rotating the stirring blade 5 at 25 rpm. When the discharge rate (discharge amount / preparation amount) reached 97% or more, it was considered that discharge was almost completed, and the time from the start of discharge was 38 seconds. Moreover, as a result of measuring the total amount of the silica aggregation solution discharged | emitted from the bottom part discharge port 3, and calculating the final discharge | emission rate, it was 98%, and there was no adhesion in a tank and it was able to discharge | emit almost all. The final emission rate was evaluated as follows: 98% or more: ◎, 97% to less than 98% ○, 90% to less than 97% △, less than 90% ×, and these results are shown in Tables 1 and 3 Indicated.

[Example 2]
A stirrer similar to that of Example 1 was used except that it had a tank with θ = 15 ° and a volume of the tank of about 0.7 m ³ . A sample similar to that in Example 1 was prepared and stirred and mixed so that the total charged amount was 520 kg (about 70% of the tank volume) to prepare a silica aggregation solution. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica agglomerated solution was discharged from the bottom outlet 3 while rotating the stirring blade 5 at 25 rpm. The time from the start of discharge until the point when the discharge rate reached 97% or more was measured, and it was 32 seconds. The final emission rate was 98.5%. The results are shown in Table 1.

[Example 3]
A stirrer similar to that of Example 1 was used except that a tank having θ = 50 ° and a tank volume of about 0.7 m ³ was used. A sample similar to that in Example 1 was prepared so that the total charged amount was 520 kg (about 70% of the tank volume), and stirred and mixed to prepare a silica aggregation solution. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica agglomerated solution was discharged from the bottom outlet 3 while rotating the stirring blade 5 at 25 rpm. It was 43 seconds when the time from the start of discharge to the time when the discharge rate reached 97% or more was measured. The final discharge rate was 97.5%. The results are shown in Table 1.

[Example 4]
A silica 20% aqueous solution 70% by weight, a polyaluminum chloride aqueous solution 3.0% by weight, and a 0.02 mol / liter HNO ₃ aqueous solution 27.0% by weight were prepared so that the total charge amount was 520 kg. The same stirrer as in Example 1 was used, and the stirring blade 5 was rotated at a rotation speed of 25 rpm for 20 minutes to mix and stir the sample, thereby preparing a silica aggregation solution. The obtained silica aggregation solution exhibited a pH of 2.5, a specific gravity of 1.16, a viscosity of 55 mPa · sec (all measured at 25 ° C.), and was a fluid having a yield value.

  The obtained silica agglomerated solution was discharged from the bottom outlet 3 while rotating the stirring blade 5 at 25 rpm. It was 50 seconds when the time from the start of discharge to the time when the discharge rate reached 97% or more was measured. The final emission rate was 98.3%. The results are shown in Tables 1 and 3.

[Reference Example 1]
A stirrer similar to that of Example 1 was used except that the tank had a θ = 60 ° and a tank volume of about 0.7 m ³ . A sample similar to that in Example 1 was prepared so that the total charged amount was 520 kg (about 70% of the tank volume), and stirred and mixed to prepare a silica aggregation solution. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica agglomerated solution was discharged from the bottom outlet 3 while rotating the stirring blade 5 at 25 rpm. The final discharge rate was 92.6%, and a slurry slightly staying on the lower inclined surface 2 was observed. The results are shown in Table 1.

[Comparative Example 1]
The same stirrer as in Reference Example 1 was used except that the clearance between the inside of the tank and the stirring blade 5 was set to a = 80 mm, b = 80 mm, and c = 80 mm, respectively. A sample similar to that in Example 1 was prepared so that the total charged amount was 520 kg (about 70% of the tank volume), and stirred and mixed to prepare a silica aggregation solution. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

The obtained silica agglomerated solution was discharged from the bottom outlet 3 while rotating the stirring blade 5 at 25 rpm. The final discharge rate was 80.0%. Even when compared with the example, the adhesion to the wall surface and the silica aggregation solution deposited on the lower inclined surface increased. The results are shown in Table 1.

  As shown in Table 1, the stirring device of the present invention preferably has a tank in which an angle θ formed by the extension line x of the rotating shaft 4 and the extension line m of the lower inclined surface 2 is less than 60 °. It can be seen that the discharge time is shortened as the value decreases. In particular, when θ is in the range of 10 ° to 55 °, it is possible to discharge almost all fluids having a viscosity of about 60 mPa · sec or less, particularly fluids having a maximum viscosity at 25 ° C. of 20 to 60 mPa · sec. . It can also be seen that not only the value of θ but also the clearance width between the tank and the stirring blade affects the discharge performance.

[Example 5]
A stirrer similar to that of Example 1 was used, except that a tank having A = 105 mm, B = 440 mm, θ = 30 °, and a volume of about 0.1 m ³ was used. Moreover, the same sample as Example 1 was prepared so that the total preparation amount might be 80 kg (about 70% of the tank volume).

  The agitation blade 5 with clearances a = 1 mm, b = 1 mm, and c = 1 mm from the inside of the tank was rotated for 20 minutes at a rotation speed of 20 rpm, and the sample was mixed and stirred to prepare a silica aggregation solution. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica aggregation solution was discharged from the bottom discharge port 3 while rotating the stirring blade 5 at 20 rpm. It was 22 seconds when the time from the start of discharge to the time when the discharge rate reached 97% or more was measured. The final emission rate was 98.5%. The results are shown in Table 2.

[Example 6]
The same stirrer as in Example 5 was used except that the clearance between the inside of the tank and the stirring blade 5 was a = 10 mm, b = 10 mm, and c = 10 mm, respectively. A sample similar to that of Example 5 was prepared so that the total charged amount was 80 kg (about 70% of the tank volume), and the sample was stirred and mixed by rotating the stirring blade 5 at a rotation speed of 20 rpm for 20 minutes. An aggregation solution was prepared. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica aggregation solution was discharged from the bottom discharge port 3 while rotating the stirring blade 5 at 20 rpm. It was 23 seconds when the time from the start of discharge until the point when the discharge rate reached 97% or more was measured. The final discharge rate was 98.0%. The results are shown in Table 2.

[Example 7]
A = 157.5mm, B = 660mm, θ = 30 °, except that it has a bath volume of about 0.3 m ^3, after the using the same stirrer as in Example 5. Moreover, the same sample as Example 5 was prepared so that a total preparation amount might be 240 kg (about 70% of the tank volume).

  The agitation blade 5 with clearances from the inside of the tank of a = 3 mm, b = 3 mm, and c = 3 mm was rotated for 20 minutes at a rotational speed of 23 rpm, and the sample was mixed and stirred to prepare a silica aggregation solution. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica agglomerated solution was discharged from the bottom discharge port 3 while rotating the stirring blade 5 at 23 rpm. The time from the start of discharge until the point when the discharge rate reached 97% or more was measured, and it was 29 seconds. The final emission rate was 98.3%. The results are shown in Table 2.

[Example 8]
The same stirrer as in Example 7 was used except that the clearance between the inside of the tank and the stirring blade 5 was set to a = 20 mm, b = 20 mm, and c = 20 mm, respectively. A sample similar to that in Example 7 was prepared so that the total charged amount was 240 kg (about 70% of the tank volume), and the sample was stirred and mixed by rotating the stirring blade 5 at a rotational speed of 23 rpm for 20 minutes. An aggregation solution was prepared. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

The obtained silica agglomerated solution was discharged from the bottom discharge port 3 while rotating the stirring blade 5 at 23 rpm. It was 33 seconds when the time from the start of discharge until the point when the discharge rate reached 97% or more was measured. The final emission rate was 97.6%. The results are shown in Table 2.

  As shown in Table 2, in an agitator with a relatively small tank capacity having an inner diameter B of about 440 to 660 mm, uniform agitation and suitable under conditions where the clearances a, b and c are about 1 to 20 mm, respectively. Discharge can be achieved.

[Example 9]
The same stirrer as in Example 1 was used except that the clearance between the inside of the tank and the stirring blade 5 was set to a = 3 mm, b = 3 mm, and c = 3 mm, respectively. A sample similar to that of Example 1 was prepared so that the total charged amount was 520 kg (about 70% of the tank volume), and the sample was stirred and mixed by rotating the stirring blade 5 at a rotation speed of 25 rpm for 20 minutes. An aggregation solution was prepared. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica agglomerated solution was discharged from the bottom outlet 3 while rotating the stirring blade 5 at 25 rpm. The time from the start of discharge until the point when the discharge rate reached 97% or more was measured, and it was 36 seconds. The final emission rate was 98.9%. The results are shown in Table 3.

[Example 10]
The same stirrer as in Example 9 was used except that the clearance between the inside of the tank and the stirring blade 5 was set to a = 30 mm, b = 30 mm, and c = 30 mm, respectively. A sample similar to that in Example 9 was prepared so that the total charged amount was 520 kg (about 70% of the tank volume), and the sample was stirred and mixed by rotating the stirring blade 5 at a rotation speed of 25 rpm for 20 minutes. An aggregation solution was prepared. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica agglomerated solution was discharged from the bottom outlet 3 while rotating the stirring blade 5 at 25 rpm. It was 40 seconds when the time from the start of discharge until the point when the discharge rate reached 97% or more was measured. The final discharge rate was 98.0%. The results are shown in Table 3.

[Example 11]
A stirrer similar to that of Example 9 was used except that a tank having A = 225 mm, B = 950 mm, θ = 30 °, and a volume of about 0.95 m ³ was used. Moreover, the same sample as Example 9 was prepared so that the total preparation amount might be 760 kg (about 70% of the tank volume).

  The agitation blade 5 with clearances a = 5 mm, b = 5 mm, and c = 5 mm from the inside of the tank was rotated for 20 minutes at a rotation speed of 27 rpm, and the sample was mixed and stirred to prepare a silica aggregate solution. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica agglomerated solution was discharged from the bottom outlet 3 while rotating the stirring blade 5 at 27 rpm. The time from the start of discharge until the point when the discharge rate reached 97% or more was measured, and it was 32 seconds. The final emission rate was 98.2%. The results are shown in Table 3.

[Example 12]
A stirrer similar to that of Example 11 was used except that the clearance between the inside of the tank and the stirring blade 5 was set to a = 35 mm, b = 35 mm, and c = 35 mm, respectively. A sample similar to that of Example 11 was prepared so that the total charged amount was 760 kg (about 70% of the tank volume), and the sample was stirred and mixed by rotating the stirring blade 5 at a rotation speed of 27 rpm for 25 minutes. An aggregation solution was prepared. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

The obtained silica agglomerated solution was discharged from the bottom outlet 3 while rotating the stirring blade 5 at 27 rpm. It was 34 seconds when the time from the start of discharge to the time when the discharge rate reached 97% or more was measured. The final emission rate was 97.7%. The results are shown in Table 3.

  As shown in Table 3, in a stirrer having a tank having an inner diameter B of about 880 to 950 mm, the clearances a, b, and c are preferably uniformly stirred and suitably discharged under conditions of about 33 to 35 mm, respectively. Can be achieved.

[Example 13]
A stirrer similar to that of Example 1 was used except that a tank having A = 240 mm, B = 1000 mm, θ = 30 °, and a volume of about 1.1 m ³ was used. Moreover, the same sample as Example 1 was prepared so that the total preparation amount might be 880 kg (about 70% of the tank volume).

  The agitation blade 5 with clearances of a = 4 mm, b = 4 mm, and c = 4 mm from the inside of the tank was rotated for 20 minutes at a rotation speed of 27 rpm, and the sample was mixed and stirred to prepare a silica aggregation solution. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica agglomerated solution was discharged from the bottom outlet 3 while rotating the stirring blade 5 at 27 rpm. The time from the start of discharge until the point when the discharge rate reached 97% or more was measured, and it was 46 seconds. The final discharge rate was 98.0%. The results are shown in Table 4.

[Example 14]
The same stirrer as in Example 13 was used except that the clearance between the inside of the tank and the stirring blade 5 was set to a = 45 mm, b = 45 mm, and c = 45 mm, respectively. A sample similar to that of Example 13 was prepared so that the total charged amount was 880 kg (about 70% of the tank volume), and the sample was stirred and mixed by rotating the stirring blade 5 at a rotation speed of 27 rpm for 20 minutes. An aggregation solution was prepared. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica agglomerated solution was discharged from the bottom outlet 3 while rotating the stirring blade 5 at 27 rpm. It was 49 seconds when the time from the start of discharge to the time when the discharge rate reached 97% or more was measured. The final discharge rate was 98.0%. The results are shown in Table 4.

[Example 15]
A stirrer similar to that of Example 1 was used except that a tank having A = 260 mm, B = 1100 mm, θ = 30 °, and a volume of about 1.4 m ³ was used. Moreover, the same sample as Example 1 was prepared so that the total preparation amount might be 1120 kg (about 70% of the tank volume).

  The agitation blade 5 with clearances a = 5 mm, b = 5 mm, and c = 5 mm from the inside of the tank was rotated for 20 minutes at a rotation speed of 30 rpm, and the sample was mixed and stirred to prepare a silica aggregation solution. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica aggregation solution was discharged from the bottom discharge port 3 while rotating the stirring blade 5 at 30 rpm. It was 50 seconds when the time from the start of discharge to the time when the discharge rate reached 97% or more was measured. The final emission rate was 98.2%. The results are shown in Table 4.

[Example 16]
The same stirrer as in Example 15 was used except that the clearance between the inside of the tank and the stirring blade 5 was set to a = 50 mm, b = 50 mm, and c = 50 mm, respectively. A sample similar to that of Example 15 was prepared so that the total charged amount was 1120 kg (about 70% of the tank volume), and the sample was stirred and mixed by rotating the stirring blade 5 at a rotation speed of 30 rpm for 20 minutes. An aggregation solution was prepared. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and was the same fluid as the solution obtained in Example 1.

  The obtained silica aggregation solution was discharged from the bottom discharge port 3 while rotating the stirring blade 5 at 30 rpm. It was 54 seconds when the time from the start of discharge until the point when the discharge rate reached 97% or more was measured. The final emission rate was 97.1%. The results are shown in Table 4.

[Reference Example 2]
The same stirrer as in Example 15 was used except that the clearance between the inside of the tank and the stirring blade 5 was set to a = 60 mm, b = 60 mm, and c = 60 mm, respectively. A sample similar to that of Example 15 was prepared so that the total charged amount was 1120 kg (about 70% of the tank volume), and the sample was stirred and mixed by rotating the stirring blade 5 at a rotation speed of 30 rpm for 20 minutes. An aggregation solution was prepared. The obtained silica aggregation solution exhibited a pH of 3.0, a specific gravity of 1.14, a viscosity of 40 mPa · sec (all measured at 25 ° C.), and the same fluid as in Example 1 was obtained.

  The obtained silica aggregation solution was discharged from the bottom discharge port 3 while rotating the stirring blade 5 at 30 rpm. The final discharge rate was 93.5%, and a slurry slightly staying on the lower inclined surface 2 was observed. The results are shown in Table 4.

[Comparative Example 2]
A stirrer similar to that of Example 15 was used except that the clearance between the inside of the tank and the stirring blade 5 was set to a = 70 mm, b = 70 mm, and c = 70 mm, respectively. A sample similar to that of Example 15 was prepared so that the total charge amount was 1120 kg (about 70% of the tank volume), and the sample was stirred and mixed by rotating the stirring blade 5 at a rotation speed of 30 rpm. The vicinity of the wall and the vicinity of the lower inclined surface were not sufficiently stirred, and a uniform silica agglomerated solution could not be prepared. The results are shown in Table 4.

[Comparative Example 3]
The same stirrer as in Example 15 was used except that the clearance between the inside of the tank and the stirring blade 5 was set to a = 0.5 mm, b = 0.5 mm, and c = 0.5 mm, respectively. A sample similar to that of Example 15 was prepared so that the total charged amount was 1120 kg (about 70% of the tank volume), and the sample was stirred and mixed by rotating the stirring blade 5 at a rotation speed of 30 rpm for 20 minutes. An aggregation solution was prepared. The obtained silica agglomerated solution was mixed with foreign substances that appeared to be metal pieces, and it was recognized that the inside of the tank or a part of the stirring blade was shaved. The results are shown in Table 4.

  As shown in Table 4, in a stirrer having an inner diameter B of about 1000 to 1100 mm, the clearances a, b, and c are each preferably about 4 to 50 mm, for example, to achieve uniform stirring and suitable discharge. Can do. On the other hand, when the clearances a, b, and c are about 60 mm, the fluid inside the tank cannot achieve a discharge rate of 97% or more, and if it exceeds 70 mm, even uniform mixing becomes difficult anymore. .

  Thus, according to this invention, it has the tank whose angle (theta) which the extension line x of the rotating shaft 4 and the extension line m of the lower inclined surface 2 make is 10-55 degrees, Preferably it is 15-50 degrees. In the stirrer, by setting the clearance between the inside of the tank and the stirring blade to 1 to 50 mm, it becomes possible to easily discharge the fluid that easily adheres to the wall surface and bottom surface of the tank and the stirring blade.

  In addition, the stirring apparatus in other embodiment of this invention can be applied suitably also in the continuous process which performs discharge | emission and mixing not only in a batch process but simultaneously.

  The present invention can be suitably used for uniform mixing and discharging of a fluid in which the obtained fluid has a yield value, and the maximum viscosity is 20 to 60 mPa · sec.

It is a longitudinal cross-sectional view which shows the outline of a structure of the stirring apparatus 100 of the fluid in embodiment of this invention. It is a longitudinal cross-sectional view which shows the outline of a structure of the stirring apparatus 200 of the fluid in embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Wall surface, 2 Lower inclined surface, 3 Bottom discharge port, 4 Rotating shaft, 5,6 Stirring blade, 10,20 Tank, 100,200 Stirrer.

Claims (4)

A stirring device comprising a tank, a stirring blade, and a bottom outlet,
A stirrer that stirs a fluid whose maximum viscosity at 25 ° C. is 20 to 60 millipascal seconds. The stirrer according to claim 1,
The stirring blade is disposed on a rotating shaft that hangs down from the outside of the tank at the center of the tank,
An agitation device, wherein an angle formed by an extension line of the rotating shaft and an extension line of a lower inclined surface of the tank is 10 ° to 55 °. The stirrer according to claim 1 or 2,
The stirring blade includes at least an anchor blade that scrapes off a fluid near a wall surface and a fluid near a bottom surface inside the tank. The stirrer according to claim 3,
The clearance between the anchor wing and the wall surface inside the tank is 1 to 50 mm,
The stirring device, wherein the clearance between the anchor blade and the bottom surface inside the tank is 1 to 50 mm.

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