JP3433620B2 - Slurry concentration method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exterior material, a roof material,
The present invention relates to a method of concentrating a slurry when manufacturing a ceramic building board such as an exterior member and an interior wall material. 2. Description of the Related Art Generally, a fiber-reinforced cement board is required to sufficiently disperse reinforcing fibers in terms of quality to exert its effect. The most effective way to disperse the fibers is to defibrate the fibers with a large excess of water, while the excess water reduces cement setting strength. In other words, industrially, fibers, cement, etc. are dispersed with as much water as possible,
In addition, it is necessary to take contradictory steps of returning the green sheet to a low moisture content green sheet as much as possible. Hitherto, for the concentration and dewatering of this slurry, methods such as papermaking (round net, long net), casting and suction have been employed. In any of the above-mentioned methods, the solid content is caked in order to forcibly remove water from the slurry, and the caked material becomes filtration resistance. Therefore, much energy and time are required for dehydration. Further, forcibly filtering the slurry, the filter medium is easily damaged and easily soiled. SUMMARY OF THE INVENTION [0004] The present invention has been made in view of the above description, and has as its object to dewater smoothly by utilizing the sedimentation action of slurry. [0005] In order to solve the above-mentioned problems, a slurry concentrating method of the present invention uses a frame-shaped weir 2 on a lower plate 1.
And a slurry 3 containing cement as a main component is filled therein. A dropper 4 having water permeability is placed on the slurry 3, and the upper opening of the weir 2 is closed with a sealing lid 15. The pressurizing air is pressed into the space between the sealing lid 15 and the dropping lid 4 in the inside, the slurry 3 is pressed by the dropping lid 4, and the water 3a on the dropping lid 4 is discharged by this pressure, and the green It is characterized in that the sheet 3b is formed. According to this, the cement or the like of the slurry 3 precipitates while holding the fiber content, and the supernatant of the precipitate hardly contains cement, fibers and the like. In the present invention, the supernatant is permeable to water. The water is dropped through the dropping lid 4 and taken out onto the lid 4, and can be dewatered by utilizing the sedimentation action of the slurry. In addition, the thickness of the green sheet 3b is regulated by the drop lid 4, and a green sheet 3b having a uniform thickness can be obtained. In addition, since dehydration is performed by pressing with the dropping lid 4, the concentration can be performed faster than the natural sedimentation speed, so that a compounding gradient hardly occurs. In addition, since the water 3a is dehydrated on the drop lid 4, dehydration can be easily performed, and dehydration can be performed speedily with energy saving. Here, as described above, when the slurry 3 in the weir 2 is pressed by the water-permeable dropping lid 4 to drop the water 3a on the lid 4 and form the green sheet 3b,
The upper opening of the weir 2 is closed by the sealing lid 15, and pressurized air is pressed into the space between the sealing lid 15 and the dropping lid 4 in the weir 2 to press the slurry with the dropping lid 4. Since the water 3a on the drop lid 4 is discharged by this pressure, in this case, the drop lid 4 is pressurized with air, so that the water 3a can be drained more smoothly, the water content can be reduced, and the water 3a is drained. Can be smooth. [0008] First, a green sheet 3b is formed.
The basic principle will be described, and then examples of embodiments of the present invention will be described. FIG. 1 (a) shows a water-permeable lower plate 1
As shown in FIG. 2, a frame-shaped weir 2 is placed, and a portion surrounded by the weir 2 is filled with slurry 3, and a permeable dropping lid 4 is placed on the slurry 3 in the weir 2. In this state, the cement, fibers and the like of the slurry 3 settle, and at the same time, the supernatant liquid water 3a is dropped and filtered on the lid 4, and FIG.
As shown in (b), the water 3a is accumulated on the drop lid 4, and the grease sheet 3b is formed between the drop lid 4 and the lower plate 1. When the slurry 3 is pressed by the dropping lid 4 to be dehydrated, the slurry is also dehydrated from the lower plate 1. After forming the green sheet 3b, the weir 2 is pulled out upward as shown in FIG. 1C, and the water 3a on the drop lid 4 is drained. Next, as shown in FIG. 1 (d), the drop lid 4 is moved upward and removed from the mold, and FIG. 1 (e).
The green sheet 3b is carried out together with the lower plate 1 as shown in FIG. The slurry 3 is mainly composed of cement,
Fibers and the like are added. The slurry concentration is 5 to 35% (weight ratio of solid to water). If the slurry concentration is less than 5%, the amount of dewatered water is large and inefficient, and if it is more than 40%, the fibers cannot be dispersed effectively. The fibers added to the slurry 3 are desirably pulp fibers or synthetic fibers, and carbon fibers, metal fibers, and inorganic fibers can also be used. The material of the permeable drop lid 4 and the lower plate 1 is a metal mesh, a synthetic fiber mesh,
There are materials such as felt and woven fabric. This material is not particularly limited, but the mesh has a mesh size of 37 to 1500 μm for collecting fibers and other fillers, and the collection rate of the fibers and other fillers for felt and woven fabric is 8 to 8 μm.
Select a material of 0% or more. 37 to 15 mesh openings
The reason why the thickness is set to 00 μm is that if the mesh is finer than 37 μm, the dehydration time becomes longer, and if the mesh is coarser than 1500 μm, the collection yield of fibers and other fillers cannot be secured to 80% or more. The skirt 6 is integrally attached to the periphery of the drop lid 4 as shown in FIG. 2A, or the apron 7 is integrally attached to the periphery of the drop lid 4 as shown in FIG. 2B. Is also good. Here, as the material of the skirt 6 and the apron 7,
A stainless steel plate (0.5 mm or less) or a plastic sheet (1.0 mm or less) is considered appropriate. When the skirt 6 and the apron 7 are provided in this manner, when the dropping lid 4 is lowered, the slurry 3 is prevented from rolling up and water 3
a can be dropped onto the lid 4 smoothly. Instead of providing the skirt 6 and the apron 7, a holding guide 8 may be attached to the periphery of the drop lid 4 as shown in FIG. 3 to eliminate the gap between the drop lid 4 and the inner surface of the weir 2. . Also in this case, the water 3a can be smoothly drained onto the drop lid 4. In this case, the holding guide 8
Can be pressed horizontally as shown in FIG.
It may be pressed diagonally as shown. This holding guide 8
It is preferable that the drop lid 4 is pressed against the inner surface of the weir 2 when the lid 4 is lowered, and is held down when the lid 4 is raised. Further down the drainage of the dewatering water 3a on the lid 4, the example above Kimoto present principles has been done by pulling on the weir 2, an example embodiment of the present invention As shown in FIG. 4, the upper surface of the weir 4 is
The pressurizing air is pressed into the space between the sealing lid 15 and the dropping lid 4 in the inside, the slurry is pressed by the dropping lid 4, and the water 3a on the dropping lid 4 is discharged by this pressure. ing. In the apparatus shown in FIG. 4, a sealing lid 15 is disposed above the drop lid 4 so as to be vertically movable.
The shaft 16 is slidably inserted into a bearing portion 17 of the sealing lid 15, and an air press-fit pipe 18 and a drain pipe 19 are attached to the sealing lid 15. Then, as shown in FIG. 4 (a), after the slurry 3 is loaded into the weir 2 and the drop lid 4 is placed thereon, the sealing lid 15 is placed on the weir 2 as shown in FIG. 4 (b). The upper surface of the weir 2 is hermetically sealed, and air is pressed into the space between the sealing lid 15 and the dropping lid 4 in the weir 2 from the air press-fitting pipe 18 as shown by an arrow a to push down the lid 4 and drop the lid. The water 3a that has flowed out of the pipe 4 is drained from the drain pipe 19 at the above pressure. When the slurry 3 is depressed and dewatered by the drop lid 4 as described above, the lower plate 1 can be dewatered from the lower plate 1 because the lower plate 1 has water permeability.
By depressurizing and dehydrating from below, the dehydrating ability can be further increased. At this time, if the drop lid 4 is pressurized from above, for example, as shown in FIG. 4, the dewatering ability can be further enhanced. This pressure is 0.05 kg /
cm ² or more of pressure you want. Further, even if a coagulant is added to the slurry 3, the dewatering effect can be enhanced. As the flocculant, a polymer flocculant (nonionic or anionic) is desirable. The amount of the coagulant added is preferably 2 to 100 ppm by weight based on the solid content of the slurry 3. In this case, 2pp
m, the effect of addition is ineffective.
There is no problem with adding m or more, but there is a large excess. If the dehydration is not sufficient when the green sheet 3b is formed as described above, the dehydration can be performed by other dehydrating means. For example, a method of dewatering by suctioning with a suction box from below the lower plate 1 on which the green sheet 3b is placed, a method of dehydrating with a roll press,
A method of dehydrating with a filter press or the like is conceivable. Further, the shapes of the lower plate 1 and the drop lid 4 may be changed. Thereby, a pattern or the like can be formed by forming a portion having a partially different thickness on the green sheet 3b. Example 1 Reference Example 1 45% by weight of cement, 35% by weight of silica, 15% by weight of fly ash and 5% by weight of pulp were blended, and a coagulant (polymer) was added at 50 ppm ( To the solid content) to prepare a slurry 3 having a solid content of 10%.
Further, a test dehydrator as shown in FIG. 5 was prepared. Drop lid 4
Is the mesh 4a on the lower side and the punched metal 4 on the upper side
b, and the opening of the mesh 4a of the drop lid 4 was 250 μm (made of SUS). The mesh size of the lower plate 1 is 250 μm (made of PET). The weir 2 was 25 cm × 25 cm in length × width. The weir 2 of the test dewatering machine was filled with the slurry 3 and, after the ripple was settled, dropped from above and the lid (with apron) 4 was lowered, and the supernatant was separated by filtration. At this time, the lower plate 1 was also made of a material having water permeability, and natural filtration was performed at the same time. The amount of the slurry 3 to be filled is 8 kg, and the pressure of the dropping lid 4 is 0.04 kg / c.
It was m ^2. After the green sheet 3b as shown in FIG. 6 (a) is formed by dehydration in this manner, the weir 2 is raised and dropped as shown in FIG. 6 (b), and the water 3a on the lid 4 is drained. As shown in (c), the drop lid 2 was removed from the mold and carried out. The green sheet 3b formed as described above
Still has about 150-200% (solids) of water, and the water content is further reduced by 60% by vacuum dehydration (solids).
Dropped below. That is, as shown in FIG. 7, the sample was placed on the suction box 10 and vacuum suction was performed from the suction box 10. The degree of vacuum at this time is 60c
Performed at mHg for 45 seconds. Furthermore, pressure dehydration was performed with a filter press. That is, as shown in FIG. 8, it was placed on the filter 11 and pressed by the press platen 12 from above.
The pressure at this time was 150 kg / cm ² for 1 second. Reference Example 2 In place of the pulp of Reference Example 1, synthetic fiber (PP: Tafite F6) was used. Others were performed similarly to Example 1. Reference Example 3 An apron, a skirt, a holding guide and the like were not used in Reference Example 1. Others were performed similarly to Example 1. REFERENCE EXAMPLE 4 In Reference Example 1, when dehydrating with a test dehydrator, the lower plate 1 was dehydrated under reduced pressure at a reduced pressure of 30 cmHg from the lower surface side. Reference Example 5 In Reference Example 1, when dewatering with the drop lid 4, a load of 1.0 Kg / cm 2 was applied to the drop lid 4. Reference Example 6 In Reference Example 1, vacuum dehydration by the suction box 10 was eliminated (filter press was performed). ( Reference Example 7) In Reference Example 1, a drop lid 4 having an uneven portion 13 as shown in FIG. 9 was used. Others are the same as the first embodiment. ( Reference Example 8) The coagulant was omitted from the formulation of the slurry 3 in Reference Example 1. Example 1 In Reference Example 1, as shown in FIG. 4, the weir 2 was sealed with a sealing lid 15 and the inside was pressurized with air, and drainage was performed from a drain pipe 19 at this pressure. . At this time, the air pressure is 0.1 kg
/ Cm ² . The sealing lid 15 was pressed at a pressure of 150 kgf to prevent leakage. (Comparative Example 1) A green sheet was formed by handsheet making and dewatered from the lower surface side only by suction. At this time, the degree of pressure reduction is 30 cmHg
Met. (Comparative Example 2) The slurry 3 was roll-pressed through a felt. The roll pressure was 40 kg / cm ² and the felt speed was 10 m / min. All of the above Reference Examples, Examples and Comparative Examples of the present invention were cured and evaluated under the same conditions as described below. <Curing> After curing by heating at a temperature of 60 ° C. for 48 hours, curing was performed in an autoclave at 170 ° C. for 6 hours. <Evaluation> Thickness variation 20 cm scan with a laser displacement sensor R = maximum thickness−minimum thickness Bending strength Measured by an autograph (Kg / cm ² ) Span 200 mm Paper making time Time until almost no drainage Reference of the present invention described above Table 1 shows the results of Examples 1 to 8, Example 1, Comparative Example 1 and Comparative Example 2. From these results, it can be seen that the reference examples and examples of the present invention have a uniform thickness of papermaking, have a short papermaking time, and can save energy (time saving) of wastewater. [Table 1] As described above, according to the present invention, a frame-shaped weir is placed on a lower plate, and a slurry containing cement as a main component is filled therein. Put the drop lid,
The upper opening of the weir is closed with a sealing lid, air for pressurization is pressed into the space between the sealing lid and the dropping lid in the weir, and the slurry is pressed by the dropping lid, and the pressure is applied to the dropping lid. The upper water is drained to form a green sheet, so the supernatant liquid of the slurry can be filtered with a water-permeable drop lid to separate the water and taken out on the lid. The thickness of the green sheet is regulated by the drop lid, and a green sheet having a uniform thickness can be obtained.Moreover, since the green sheet is pressed by the drop lid and dehydrated, it can be concentrated faster than the natural sedimentation speed. Therefore, the compounding gradient is less likely to occur, and the water can be easily dewatered on the dropping lid because the water is dewatered, so that the dehydration can be performed energy-saving and speedily. In particular, when the green sheet is formed by pressing the slurry in the weir with the permeable drop lid and draining water on the drop lid, the upper opening of the weir is closed with the sealing lid and the inside of the weir is closed. Press the air for pressurization into the space between the sealing lid and the dropping lid, press the slurry with the dropping lid and discharge the water on the dropping lid with this pressure, so press the dropping lid with air. Water can be drained more smoothly, the water content can be reduced, and the drainage of water can be performed more smoothly.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a process in an example of a basic principle of forming a green sheet, and (a), (b), (c), (d), and (e) are cross-sectional views of each process. It is. FIG. 2A is an explanatory view showing a state in which a skirt is provided on the dropping lid, and FIG. 2B is an explanatory view showing a state in which an apron is provided on the dropping lid. FIGS. 3A and 3B are cross-sectional views showing a state in which a holding guide is provided on the dropping lid according to the first embodiment. FIG. 4 shows the steps of an example of an embodiment of the present invention, wherein (a)
(B) is sectional drawing of each process. FIG. 5 is a cross-sectional view of the test dehydrator of Reference Example 1 . FIGS. 6A, 6B, and 6C are cross-sectional views illustrating steps of Reference Example 1. FIGS. FIG. 7 is a cross-sectional view of Reference Example 1 in a state where vacuum dehydration is performed. FIG. 8 is a cross-sectional view illustrating a filter press of Reference Example 1 . FIG. 9 is a cross-sectional view of the test dehydrator of Reference Example 7. [Description of Signs] 1 Lower plate 2 Weir 3 Slurry 3a Water 3b Green sheet 4 Drop lid 15 Sealing lid 18 Air press-fit pipe 19 Drain pipe

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-320805 (JP, A) JP-A-6-339908 (JP, A) JP-A-53-71118 (JP, A) 68604 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B28B 3/02

Claims (1)

(57) [Claims 1] A frame-shaped weir is placed on a lower plate, a slurry containing cement as a main component is filled, and a dropper having water permeability is put on the slurry. Is placed, and the upper opening of the weir is closed with a sealing lid. Air for pressurization is pressed into the space between the sealing lid and the dropping lid in the weir, and the slurry is pressed by the dropping lid, and the pressure is applied at this pressure. A slurry concentrating method, comprising discharging water on a drop lid to form a green sheet.