CA1316462C - Method for the manufacture of plates, filter plate, and suction drier - Google Patents
Method for the manufacture of plates, filter plate, and suction drierInfo
- Publication number
- CA1316462C CA1316462C CA000524545A CA524545A CA1316462C CA 1316462 C CA1316462 C CA 1316462C CA 000524545 A CA000524545 A CA 000524545A CA 524545 A CA524545 A CA 524545A CA 1316462 C CA1316462 C CA 1316462C
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- interior space
- suction
- filter plate
- microporous
- plate
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Abstract
ABSTRACT OF THE DISCLOSURE
The invention concerns a method for the manufacture of a plate, in which a gypsum mould is first filled with casting mix. Hereinafter water is absorbed out of the casting mix into the gypsum, and a crust is allowed to remain on the face of the mould. The crust is allowed to develop to appropriate thickness, whereupon the excess casting mix is poured off. After the inside faces of the crust have become dry, the mould is filled with a granular material, which has preferably the same composition as that of the crust material. The invention also concerns a filter plate, which comprises a space placed between filter faces and filled with a granular material. The invention further concerns a suction drier, in which the filter plate is used so that at least one filter plate can be shifted into communication with the material to be dewatered in a basin or equivalent. The apparatus concerned comprises preferably several filter plates, which are fitted about a rotating shaft as a circular structure. A nega-tive pressure is applied to the suction faces of each plate, whereby water or any other liquid is shifted out of the material to be dewatered through the suction faces into the central space and further, drawn by the negative pressure, out of the plate structure.
The invention concerns a method for the manufacture of a plate, in which a gypsum mould is first filled with casting mix. Hereinafter water is absorbed out of the casting mix into the gypsum, and a crust is allowed to remain on the face of the mould. The crust is allowed to develop to appropriate thickness, whereupon the excess casting mix is poured off. After the inside faces of the crust have become dry, the mould is filled with a granular material, which has preferably the same composition as that of the crust material. The invention also concerns a filter plate, which comprises a space placed between filter faces and filled with a granular material. The invention further concerns a suction drier, in which the filter plate is used so that at least one filter plate can be shifted into communication with the material to be dewatered in a basin or equivalent. The apparatus concerned comprises preferably several filter plates, which are fitted about a rotating shaft as a circular structure. A nega-tive pressure is applied to the suction faces of each plate, whereby water or any other liquid is shifted out of the material to be dewatered through the suction faces into the central space and further, drawn by the negative pressure, out of the plate structure.
Description
1 3 1 6 4 r) This invention relates to a method of manufacturing a plate, in particular a filter plate.
The invention also relates to a filter plate and a suction drier making use of the filter plates of the type concerned.
For various duties, microporous plates are needed. In the applicant's FI Patent No. 61,739 (corresponds to U.SO
Patent No. 4,357,758), a method for the dewatering of a porous material, web-like material such as paper, floury material such as peat, solid material such as wood, as well as the filter plates needed in connection with the said method are described. According to the method of the said patent, the subject to be dewatered is brought through a finely porous suction face filled with liquid into hydraulic connection with a liquid subjected to a negative pressure in relation to the subject to be dewatered.
From the applicant's earlier patent FI 67 180, a method for the manufacture of plate and a plate in accordance with the method are known. The manufacture of the plate concerned is based on an extrusion method.
In a method aspect, the invention provides a method of manufacturing a microporous plate, particularly useful as a filter plate, comprising the steps of: preparing a casting mix by adding water to a casting material; introducing the casting mix into an interior of a casting mold having opposed mold walls formed of an absorbent material; allowing water of the casting mix to be absorbed into the walls of the casting mold until a solid crust is formed from the casting mix on inner surfaces of the opposed mold walls, the crust ,,s:
1 31 64h~
comprising opposed porous crust wall portions defining an interior space between them; draining the casting mix remaining within the interior space between the opposed crust wall portions upon the crust wall portions having developed an appropriate thickness; and filling the interior space within the crust wall portions with a granular material to provide reinforcement for the crust wall portions and form the microporous plate.
In preferred embodiments of thls aspect, the invention provides The above method wherein the casting mold walls are formed of gypsum.
The above method wherein the granular material is formed of the same material as the material of which the crust is formed.
The above method wherein the casting material from which the crust is formed also includes dispersing agents.
The above method wherein the casting material comprises a material having a specific weight of about 1750 kg/m3, a viscosity of about 1000 cP and a water content of less than about 33%.
The above method including the further step of washing the interior space between the opposed crust wall portions and the granular material filling the interior space with a sludge material; and wherein the sludge material and the granular material are formed of the same material as the material of which the crust is formed.
~, .. ..
1 31 646~
The above method wherein the granular material is formed of the same material as the material of which the crust is formed, the material comprising a ceramic material; and wherein the plate in finished form comprises about 55%
aluminum hydroxide, about 40% silicon dioxide, and about 5%
calcium oxide and wherein said casting material comprises about 20~ clay, about 30% kaolin, about 45% aluminum hydroxide, and about 5% calcium carbonate; and wherein the casting material is formed of raw material in particulate form, the particles of raw material having an average size of about 0.002 mm.
The above method wherein the mold has a filling opening and the crust formed in the mold further comprises crust duct portions defining a water duct communicating with the interior space between the opposed crust wall portions, and including the further steps of: after forming the microporous plate, closing the filling opening of the mold with a strip formed of the casting mix; detaching the microporous plate from the inner surfaces of the opposed mold walls; opening the mold; allowing the plate to dry; glazing the water duct and edges of the plate; and heating the plate in an oven; and wherein the heating step comprises raising the temperature of the oven slowly to a high temperature of about 1320C. and maintaining the high temperature for about two hours; and wherein the heating step has a duration of about 48 hours.
The above method wherein the casting material from which the crust is formed comprises clay, kaolin, aluminum hydroxide and calcium carbonate.
In a product aspect, the invention provides a 1 31 6~16^
microporous filter plate comprising: a pair of opposed suction walls formed of microporous material defining an interior space between them; granular material situated in said interior space between said opposed suction walls; and means for placing said interior space in communication with a negative pressure; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
In preferred embodiments of this aspect, the invention provides:
The above combination where said means for placing said interior space in communication with a negative pressure includes a duct passing into said interior between said microporous suction walls from outside said plate.
The above combination wherein said filter plate has a length and a thickness, and wherein the ratio of the length to the thickness of the filter plate is greater than about 30.
The above combination wherein each suction wall has a length and a thickness, and wherein the ratio of the length to the thickness, and wherein the ratio of the length to the thickness of the suction wall is greater than about 120.
The above combination, wherein said granular material comprises a ceramic material; and wherein said suction walls are formed of ceramic material.
t~ ''' `' 1316~6^
The above combination, wherein said granular material does not present a major resistance to liquid flow in said interior space.
The above combination, wherein said granular material does not prevent suctioning of liquid from said interior space, but acts to reinforce the structure of said plate.
In a further product aspect, the invention provides suction drier apparatus, comprising: at least one filter plate formed of a pair of opposed suction walls formed of microporous material defining an interior space between them and granular material situated in said interior space between said opposed suction walls; means on which said at least one filter plate is mounted for moving said filter plate into and out of a basin or the like in which material to be dewatered is present; and means for reducing the pressure within said interior space of said filter plate to a negative pressure to remove water from the material being dewatered through said suction walls into said interior space.
In preferr~d embodiments of this aspect, the invention provides:
The above combination, wherein said suction drier apparatus comprises a plurality of said filter plates mounted in a circular array connected to a rotatably mounted shaft so that each filter plate is lowered into and then raised from said basin or the like, and a suction tube associated with said shaft and communicating with the interiors of said filter plates; and wherein each filter plate includes a duct communicating with said suction tube such that ths pressure in said interior space of said filter p]ate is reduced by - 4a -. .~
1 31 6~)2 applyin~ suction to said suctlon tube thereby applying a negative pressure to said suction walls of said filter plates whereby water is suctioned from said material being dewatered through said suction walls into said interior spaces and further out of each plate through said duct; and wherein the material being dewatered adheres under the force of suction to each said filter plate as each said filter plate is raided out of said basin or the like so that dewatering of said material continues, and further including means for removing the material being dewatered from each filter plate as each filter plate reaches a certain position; and wherein said means for removing the material to be dewatered from said filter plates comprises scraper blades.
In a still further product aspect, the invention provides a microporous filter plate comprising: a pair of opposed suction walls formed of microporous material defining an interior space between them, said suction walls being formed of a mix comprising clay, kaolin, aluminum hydroxide and calcium carbonate; and granular material situated in said interior space between said opposed suction walls; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
In a preferred embodiment of this aspect, the invention provides:
The above combinatiGn, wherein said suction walls are formed of a mix comprising about 20% clay, about 30% kaolin, about 45% aluminum hydroxide and about 5% calcium carbonate.
- 4b -1316~
The invention also provides a microporous filter plate comprising: a pair of opposed suction walls formed of microporous material defining an interior space between them;
and granular material situated in said interior space between said opposed suction walls, said granular material being formed of the same material as the material of which said suction walls are formed; whereby said filter plate is adapted to brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
In a preferred embodiment of this aspect, the granular material comprises a ceramic material.
Further, the invention provides:
A microporous filter plate comprising: a pair of opposed suction walls formed of microporous material defining an interior space between them; granular material situated in said interior space between said opposed suction wall; and means for placing said interior space in communication with a negative pressure; wherein said filter plate in finished form comprises a composition of about 55% aluminum hydroxide, about 40% silicon dioxide, and about 5% calcium oxide;
whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
A microporous filter plate comprising: a pair of opposed suction walls formed of microporous material defining - 4c -131)4~'' an interior space between them; granular material situated in said interior space between said opposed suctlon walls; and means for placing said interior space in communication with a negative pressure; wherein particles of said granular material have an average size in the range of between about 0.0010 and 0.0015 mm; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which:-Figure 1 shows a filter plate of the invention as viewed15 from above;
Figure 2 is a partial sectional view of the filter plate shown in Fig. 1 along line I-I in Fig. l; and Figure 3 shows in side view a suction drier in accordance with the invention, wherein filter plates in accordance with the invention are used.
The method of the invention for the manufacture of the plate comprises the following steps. Preferably a gypsum mould or equivalent divided into two parts is used. The mould is kept upright so that the neck part of the mould is directed downwards. The mould is filled with casting mix.
Water is absorbed from the mix into the mould, and a thin crust remains on the face of the mould. The waiting time before the next step is about 30 minutes. After the crust - 4d -, J ~ . ., .
1 31 6~
has developed during this period of time to appropriate thickness, the excess casting mix is poured out of the mould.
Now there is another waiting time of about 30 minutes, 50 that the inside faces become dry. The plate is then filled with - ~e -" ~;, , . -"~r.~' ' 1 3 1 6~
a granular material, which has preferably the same drysolids composition as that of the casting mix itself.
After filling, the granules are washed with a thin sludge, which is made of the same casting mix. The said thin sludge water penetrates into the spaces between the granules and acts as a material connecting the granules with each other as well as a material connecting the structure of granules to the walls. After the said filling with sludge, there is a waiting time of about 15 seconds, and thereupon emptying. The emptying opening is then closed tightly with a strip of mix.
After the plate has been detached from the mould faces, the mould is opened, and the plate is made clean of casting overflow. ~ereinafter the plate is allowed to dry slowlv for about 2 hours. At the casting stage, a water duct has been made into the middle part of the plate, so that the water that has entered into the said granular middle part is sucked further via the said water duct out of the plate. After the drying stage, the said water duct and the edges of the plate are glazed.
Hereinafter the plate is burnt in an oven at a temperature of about 1320C so that the temperature is raised slowly and so that the entire burning process takes about 48 hours. The highest temperature itself is maintained for about 2 hours.
The method concerned is advantageously suitable exactly for the manufacture of filter plates which are intended for use as a porous material in suction drying in which the subject to be dewatered has been brought, by the intermediate of a finely porous suction face saturated with liquid, into hydraulic connection with a liquid subjected to a negative pressure in relation to the subject to be dewatered. However, the method is not supposed to be confined to the manufacture of filter plates alone.
6 1 31 ~46 ' Figures 1 and 2 show a filter plate 10, pre-ferably manufactured exactly by the method of the inven-tion. The filter plate 10 comprises a first suction face 11 and a second suction face 12, between which there is a space 14 filled with granules 13. The said inter-mediate space acts as a water space. The granules are essent~ally limited by the first face 11 and by the second face 12. They act as a rigidifier of the struc-ture, and owing to their granular nature, they do, how-ever, not prevent flow of the liquid that has enteredinto the said central space, because the granules do not produce a major resistance to flow. A duct 15 passes into the said central space 14, which said duct can be connected further to a source of negative pressure so as to produce flow of liquid through the suction faces 11 and/or 12 into the central space 14 and further out of the filter plate 10.
The duct 15 in the plate as well as the edges 16 o the plate are reinforced by means of glazing.
Moreover, the plate may be provided with fastenings 17. The said fastenings 17 may act as means for attaching the plate 10 to its base. The space 14 filled with granules supports the suction faces 11 and 12 against pressure.
The suction faces 11 and 12 of the plate as well as the granules 13 are made of a preferably ceramic casting mix, whose composition is as follows:
- clay about 20 ~
- kaolin about 30 %
- aluminium hydroxide about 45 ~, and - calcium carbonate about 5 %.
The particle size of the raw-materials is on the average 0.002 mm. The following physical pro-perties are required from a ceramic cas-ting mix. Its specific weight is about 1750 kg/m3. Its viscosity is about 1000 cP, and its water content is less than 33 %.
The granules 13 in the space 14 in the plate 10 are 1 31 6~' ' preferably made of the same porous material as ~he suction faces 11 and 12 of the plate 10 itself. Thus, the finished plate consists of a porous ceramic material, which is composed of:
- aluminium hydroxide about 55 - silicon dioxide about 40 %
- calcium oxide about 5 %.
The particle size is on the average 0.0010 to 0~0015 mm.
Moreover, dispersing agents are used, such as sodium polyacrylate, which is used as an additive in order to provide the desired composition.
Fig. 3 shows a suction drier 18. The drier 18 preferably comprises several filter plates 10, prefer-ably manufactured by the méthod of manufacture in accord-ance with the invention. The plates 10 are installed asa circular structure so that the duct 15 of each plate 10 is connected to a central suction ~ube 19, which is placed on the rotating shaft. Each filter plate 10 is connected by a duct 20 to the said central tube 19. The plates 10 are fitted 50 that they pass through the basin 21. The basin 21 may be filled with peat sludge or with some other, corresponding material to be de-watered. Negative pressure is passed through the central tube 19 and the ducts 20 into the filter plates 10. Owing to the porous structure of the filter plates, the sludge provided in the basin 21, from which sludge the liquid is to be removed, is carried by the effect of the negative pressure applied to the centre of the filter plates to against the suction faces of the plates 10. The water in the sludge in the basin 21 is sucked further, by the effect of the negative pressure, through the suction faces 11 and 12 of the filter plates 10 into the central space 14 and further along the ducts 20 into the central tube 19 and out of the structure.
~s the filter plates 10 are placed in circular form around the central tube or shaft 19 and as the shaft 19 is fitted as revolving, each filter plate 10 1 31 64') ' in its turn moves into the basin 21 and further, as -the rotating shaft revolves, rises out of the basin. By the effect of the negative pressure, material to be dewatered, adhering to the suc-tion faces 11 and 12 of the pla-tes, rises along with the filter plates 10 out of the basin 21. As the negative pressure is main-tained, the dewatering of the material goes on during the said rising movement, and after the material to be dewatered, e.g.
peat, has been carried, e.g., to point A of the structure shown in Fig. 3, scraper blades or other detaching members detach the material from the suction faces 11 and 12, and the dewatered material is shifted apart from the plates and the apparatus. The construction further includes a support frame 22, which is fitted so that it supports the basin 21. The basin 21 is provided with an outlet pipe 23. The apparatus further includes a storage tank 24 for the material to be dewatered, which said tank is again provided with an outlet duct 25. An electric motor is fitted to rotate the central rotating shaft and the tube 19.
In the suction drier 18 of the invention, the suction faces 11 and 12 of the filter plates 10 operate expressly as suc-tion faces saturated with liquid, which means that air (or gas in general) does not pass through the suction face at the pressure differences between air and liquid used in the dewatering method.
In the suction drier 18 of the invention, the subject to be dewa-tered is brought through the suction face 11 and/or 12 of a finely porous plate 10 saturated with liquid, into hydraulic con-nection with a liquid subjected to a negative pressure in rela-tion to the subject to be dewatered. The apparatus of the inven-tion is intended in particular for the dewatering of peat, but it is to be emphasized that the apparatus is also suitable for the dewatering of many other materials. Also, it is to be emphasized that, instead of water, the liquid sucked by the apparatus 18 of ;the invention may be another liquid 0
The invention also relates to a filter plate and a suction drier making use of the filter plates of the type concerned.
For various duties, microporous plates are needed. In the applicant's FI Patent No. 61,739 (corresponds to U.SO
Patent No. 4,357,758), a method for the dewatering of a porous material, web-like material such as paper, floury material such as peat, solid material such as wood, as well as the filter plates needed in connection with the said method are described. According to the method of the said patent, the subject to be dewatered is brought through a finely porous suction face filled with liquid into hydraulic connection with a liquid subjected to a negative pressure in relation to the subject to be dewatered.
From the applicant's earlier patent FI 67 180, a method for the manufacture of plate and a plate in accordance with the method are known. The manufacture of the plate concerned is based on an extrusion method.
In a method aspect, the invention provides a method of manufacturing a microporous plate, particularly useful as a filter plate, comprising the steps of: preparing a casting mix by adding water to a casting material; introducing the casting mix into an interior of a casting mold having opposed mold walls formed of an absorbent material; allowing water of the casting mix to be absorbed into the walls of the casting mold until a solid crust is formed from the casting mix on inner surfaces of the opposed mold walls, the crust ,,s:
1 31 64h~
comprising opposed porous crust wall portions defining an interior space between them; draining the casting mix remaining within the interior space between the opposed crust wall portions upon the crust wall portions having developed an appropriate thickness; and filling the interior space within the crust wall portions with a granular material to provide reinforcement for the crust wall portions and form the microporous plate.
In preferred embodiments of thls aspect, the invention provides The above method wherein the casting mold walls are formed of gypsum.
The above method wherein the granular material is formed of the same material as the material of which the crust is formed.
The above method wherein the casting material from which the crust is formed also includes dispersing agents.
The above method wherein the casting material comprises a material having a specific weight of about 1750 kg/m3, a viscosity of about 1000 cP and a water content of less than about 33%.
The above method including the further step of washing the interior space between the opposed crust wall portions and the granular material filling the interior space with a sludge material; and wherein the sludge material and the granular material are formed of the same material as the material of which the crust is formed.
~, .. ..
1 31 646~
The above method wherein the granular material is formed of the same material as the material of which the crust is formed, the material comprising a ceramic material; and wherein the plate in finished form comprises about 55%
aluminum hydroxide, about 40% silicon dioxide, and about 5%
calcium oxide and wherein said casting material comprises about 20~ clay, about 30% kaolin, about 45% aluminum hydroxide, and about 5% calcium carbonate; and wherein the casting material is formed of raw material in particulate form, the particles of raw material having an average size of about 0.002 mm.
The above method wherein the mold has a filling opening and the crust formed in the mold further comprises crust duct portions defining a water duct communicating with the interior space between the opposed crust wall portions, and including the further steps of: after forming the microporous plate, closing the filling opening of the mold with a strip formed of the casting mix; detaching the microporous plate from the inner surfaces of the opposed mold walls; opening the mold; allowing the plate to dry; glazing the water duct and edges of the plate; and heating the plate in an oven; and wherein the heating step comprises raising the temperature of the oven slowly to a high temperature of about 1320C. and maintaining the high temperature for about two hours; and wherein the heating step has a duration of about 48 hours.
The above method wherein the casting material from which the crust is formed comprises clay, kaolin, aluminum hydroxide and calcium carbonate.
In a product aspect, the invention provides a 1 31 6~16^
microporous filter plate comprising: a pair of opposed suction walls formed of microporous material defining an interior space between them; granular material situated in said interior space between said opposed suction walls; and means for placing said interior space in communication with a negative pressure; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
In preferred embodiments of this aspect, the invention provides:
The above combination where said means for placing said interior space in communication with a negative pressure includes a duct passing into said interior between said microporous suction walls from outside said plate.
The above combination wherein said filter plate has a length and a thickness, and wherein the ratio of the length to the thickness of the filter plate is greater than about 30.
The above combination wherein each suction wall has a length and a thickness, and wherein the ratio of the length to the thickness, and wherein the ratio of the length to the thickness of the suction wall is greater than about 120.
The above combination, wherein said granular material comprises a ceramic material; and wherein said suction walls are formed of ceramic material.
t~ ''' `' 1316~6^
The above combination, wherein said granular material does not present a major resistance to liquid flow in said interior space.
The above combination, wherein said granular material does not prevent suctioning of liquid from said interior space, but acts to reinforce the structure of said plate.
In a further product aspect, the invention provides suction drier apparatus, comprising: at least one filter plate formed of a pair of opposed suction walls formed of microporous material defining an interior space between them and granular material situated in said interior space between said opposed suction walls; means on which said at least one filter plate is mounted for moving said filter plate into and out of a basin or the like in which material to be dewatered is present; and means for reducing the pressure within said interior space of said filter plate to a negative pressure to remove water from the material being dewatered through said suction walls into said interior space.
In preferr~d embodiments of this aspect, the invention provides:
The above combination, wherein said suction drier apparatus comprises a plurality of said filter plates mounted in a circular array connected to a rotatably mounted shaft so that each filter plate is lowered into and then raised from said basin or the like, and a suction tube associated with said shaft and communicating with the interiors of said filter plates; and wherein each filter plate includes a duct communicating with said suction tube such that ths pressure in said interior space of said filter p]ate is reduced by - 4a -. .~
1 31 6~)2 applyin~ suction to said suctlon tube thereby applying a negative pressure to said suction walls of said filter plates whereby water is suctioned from said material being dewatered through said suction walls into said interior spaces and further out of each plate through said duct; and wherein the material being dewatered adheres under the force of suction to each said filter plate as each said filter plate is raided out of said basin or the like so that dewatering of said material continues, and further including means for removing the material being dewatered from each filter plate as each filter plate reaches a certain position; and wherein said means for removing the material to be dewatered from said filter plates comprises scraper blades.
In a still further product aspect, the invention provides a microporous filter plate comprising: a pair of opposed suction walls formed of microporous material defining an interior space between them, said suction walls being formed of a mix comprising clay, kaolin, aluminum hydroxide and calcium carbonate; and granular material situated in said interior space between said opposed suction walls; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
In a preferred embodiment of this aspect, the invention provides:
The above combinatiGn, wherein said suction walls are formed of a mix comprising about 20% clay, about 30% kaolin, about 45% aluminum hydroxide and about 5% calcium carbonate.
- 4b -1316~
The invention also provides a microporous filter plate comprising: a pair of opposed suction walls formed of microporous material defining an interior space between them;
and granular material situated in said interior space between said opposed suction walls, said granular material being formed of the same material as the material of which said suction walls are formed; whereby said filter plate is adapted to brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
In a preferred embodiment of this aspect, the granular material comprises a ceramic material.
Further, the invention provides:
A microporous filter plate comprising: a pair of opposed suction walls formed of microporous material defining an interior space between them; granular material situated in said interior space between said opposed suction wall; and means for placing said interior space in communication with a negative pressure; wherein said filter plate in finished form comprises a composition of about 55% aluminum hydroxide, about 40% silicon dioxide, and about 5% calcium oxide;
whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
A microporous filter plate comprising: a pair of opposed suction walls formed of microporous material defining - 4c -131)4~'' an interior space between them; granular material situated in said interior space between said opposed suctlon walls; and means for placing said interior space in communication with a negative pressure; wherein particles of said granular material have an average size in the range of between about 0.0010 and 0.0015 mm; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
The invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which:-Figure 1 shows a filter plate of the invention as viewed15 from above;
Figure 2 is a partial sectional view of the filter plate shown in Fig. 1 along line I-I in Fig. l; and Figure 3 shows in side view a suction drier in accordance with the invention, wherein filter plates in accordance with the invention are used.
The method of the invention for the manufacture of the plate comprises the following steps. Preferably a gypsum mould or equivalent divided into two parts is used. The mould is kept upright so that the neck part of the mould is directed downwards. The mould is filled with casting mix.
Water is absorbed from the mix into the mould, and a thin crust remains on the face of the mould. The waiting time before the next step is about 30 minutes. After the crust - 4d -, J ~ . ., .
1 31 6~
has developed during this period of time to appropriate thickness, the excess casting mix is poured out of the mould.
Now there is another waiting time of about 30 minutes, 50 that the inside faces become dry. The plate is then filled with - ~e -" ~;, , . -"~r.~' ' 1 3 1 6~
a granular material, which has preferably the same drysolids composition as that of the casting mix itself.
After filling, the granules are washed with a thin sludge, which is made of the same casting mix. The said thin sludge water penetrates into the spaces between the granules and acts as a material connecting the granules with each other as well as a material connecting the structure of granules to the walls. After the said filling with sludge, there is a waiting time of about 15 seconds, and thereupon emptying. The emptying opening is then closed tightly with a strip of mix.
After the plate has been detached from the mould faces, the mould is opened, and the plate is made clean of casting overflow. ~ereinafter the plate is allowed to dry slowlv for about 2 hours. At the casting stage, a water duct has been made into the middle part of the plate, so that the water that has entered into the said granular middle part is sucked further via the said water duct out of the plate. After the drying stage, the said water duct and the edges of the plate are glazed.
Hereinafter the plate is burnt in an oven at a temperature of about 1320C so that the temperature is raised slowly and so that the entire burning process takes about 48 hours. The highest temperature itself is maintained for about 2 hours.
The method concerned is advantageously suitable exactly for the manufacture of filter plates which are intended for use as a porous material in suction drying in which the subject to be dewatered has been brought, by the intermediate of a finely porous suction face saturated with liquid, into hydraulic connection with a liquid subjected to a negative pressure in relation to the subject to be dewatered. However, the method is not supposed to be confined to the manufacture of filter plates alone.
6 1 31 ~46 ' Figures 1 and 2 show a filter plate 10, pre-ferably manufactured exactly by the method of the inven-tion. The filter plate 10 comprises a first suction face 11 and a second suction face 12, between which there is a space 14 filled with granules 13. The said inter-mediate space acts as a water space. The granules are essent~ally limited by the first face 11 and by the second face 12. They act as a rigidifier of the struc-ture, and owing to their granular nature, they do, how-ever, not prevent flow of the liquid that has enteredinto the said central space, because the granules do not produce a major resistance to flow. A duct 15 passes into the said central space 14, which said duct can be connected further to a source of negative pressure so as to produce flow of liquid through the suction faces 11 and/or 12 into the central space 14 and further out of the filter plate 10.
The duct 15 in the plate as well as the edges 16 o the plate are reinforced by means of glazing.
Moreover, the plate may be provided with fastenings 17. The said fastenings 17 may act as means for attaching the plate 10 to its base. The space 14 filled with granules supports the suction faces 11 and 12 against pressure.
The suction faces 11 and 12 of the plate as well as the granules 13 are made of a preferably ceramic casting mix, whose composition is as follows:
- clay about 20 ~
- kaolin about 30 %
- aluminium hydroxide about 45 ~, and - calcium carbonate about 5 %.
The particle size of the raw-materials is on the average 0.002 mm. The following physical pro-perties are required from a ceramic cas-ting mix. Its specific weight is about 1750 kg/m3. Its viscosity is about 1000 cP, and its water content is less than 33 %.
The granules 13 in the space 14 in the plate 10 are 1 31 6~' ' preferably made of the same porous material as ~he suction faces 11 and 12 of the plate 10 itself. Thus, the finished plate consists of a porous ceramic material, which is composed of:
- aluminium hydroxide about 55 - silicon dioxide about 40 %
- calcium oxide about 5 %.
The particle size is on the average 0.0010 to 0~0015 mm.
Moreover, dispersing agents are used, such as sodium polyacrylate, which is used as an additive in order to provide the desired composition.
Fig. 3 shows a suction drier 18. The drier 18 preferably comprises several filter plates 10, prefer-ably manufactured by the méthod of manufacture in accord-ance with the invention. The plates 10 are installed asa circular structure so that the duct 15 of each plate 10 is connected to a central suction ~ube 19, which is placed on the rotating shaft. Each filter plate 10 is connected by a duct 20 to the said central tube 19. The plates 10 are fitted 50 that they pass through the basin 21. The basin 21 may be filled with peat sludge or with some other, corresponding material to be de-watered. Negative pressure is passed through the central tube 19 and the ducts 20 into the filter plates 10. Owing to the porous structure of the filter plates, the sludge provided in the basin 21, from which sludge the liquid is to be removed, is carried by the effect of the negative pressure applied to the centre of the filter plates to against the suction faces of the plates 10. The water in the sludge in the basin 21 is sucked further, by the effect of the negative pressure, through the suction faces 11 and 12 of the filter plates 10 into the central space 14 and further along the ducts 20 into the central tube 19 and out of the structure.
~s the filter plates 10 are placed in circular form around the central tube or shaft 19 and as the shaft 19 is fitted as revolving, each filter plate 10 1 31 64') ' in its turn moves into the basin 21 and further, as -the rotating shaft revolves, rises out of the basin. By the effect of the negative pressure, material to be dewatered, adhering to the suc-tion faces 11 and 12 of the pla-tes, rises along with the filter plates 10 out of the basin 21. As the negative pressure is main-tained, the dewatering of the material goes on during the said rising movement, and after the material to be dewatered, e.g.
peat, has been carried, e.g., to point A of the structure shown in Fig. 3, scraper blades or other detaching members detach the material from the suction faces 11 and 12, and the dewatered material is shifted apart from the plates and the apparatus. The construction further includes a support frame 22, which is fitted so that it supports the basin 21. The basin 21 is provided with an outlet pipe 23. The apparatus further includes a storage tank 24 for the material to be dewatered, which said tank is again provided with an outlet duct 25. An electric motor is fitted to rotate the central rotating shaft and the tube 19.
In the suction drier 18 of the invention, the suction faces 11 and 12 of the filter plates 10 operate expressly as suc-tion faces saturated with liquid, which means that air (or gas in general) does not pass through the suction face at the pressure differences between air and liquid used in the dewatering method.
In the suction drier 18 of the invention, the subject to be dewa-tered is brought through the suction face 11 and/or 12 of a finely porous plate 10 saturated with liquid, into hydraulic con-nection with a liquid subjected to a negative pressure in rela-tion to the subject to be dewatered. The apparatus of the inven-tion is intended in particular for the dewatering of peat, but it is to be emphasized that the apparatus is also suitable for the dewatering of many other materials. Also, it is to be emphasized that, instead of water, the liquid sucked by the apparatus 18 of ;the invention may be another liquid 0
Claims (34)
1. A method of manufacturing a microporous plate, particularly useful as a filter plate, comprising the steps of:
preparing a casting mix by adding water to a casting material; introducing the casting mix into an interior of a casting mold having opposed mold walls formed of an absorbent material; allowing water of the casting mix to be absorbed into the walls of the casting mold until a solid crust is formed from the casting mix on inner surfaces of the opposed mold walls, the crust comprising opposed porous crust wall portions defining an interior space between them, draining the casting mix remaining within the interior space between the opposed crust wall portions upon the crust wall portions having developed an appropriate thickness; and filling the interior space within the crust wall portions with a granular material to provide reinforcement for the crust wall portions and form the microporous plate.
preparing a casting mix by adding water to a casting material; introducing the casting mix into an interior of a casting mold having opposed mold walls formed of an absorbent material; allowing water of the casting mix to be absorbed into the walls of the casting mold until a solid crust is formed from the casting mix on inner surfaces of the opposed mold walls, the crust comprising opposed porous crust wall portions defining an interior space between them, draining the casting mix remaining within the interior space between the opposed crust wall portions upon the crust wall portions having developed an appropriate thickness; and filling the interior space within the crust wall portions with a granular material to provide reinforcement for the crust wall portions and form the microporous plate.
2. The method of claim 1 wherein the casting mold walls are formed of gypsum.
3. The method of claim 1 wherein the granular material is formed of the same material as the material of which the crust is formed.
4. The method of claim 1 wherein the casting material from which the crust is formed also includes dispersing agents.
5. The method of claim 1 wherein the casting material comprises a material having a specific weight of about 1750 kg/m3, a viscosity of about 1000 cP and a water content of less than about 33%.
6. The method of claim 1 including the further step of washing the interior space between the opposed crust wall portions and the granular material filling the interior space with a sludge material.
7. The method of claim 6 wherein the sludge material and the granular material are formed of the same material as the material of which the crust is formed.
8. The method of claim 1 wherein the granular material is formed of the same material as the material of which the crust is formed, the material comprising a ceramic material.
9. The method of claim 8 wherein the plate in finished form comprises about 55% aluminum hydroxide, about 40%
silicon dioxide, and about 5% calcium oxide.
silicon dioxide, and about 5% calcium oxide.
10. The method of claim 1 wherein the mold has a filling opening and the crust formed in the mold further comprises crust duct portions defining a water duct communicating with the interior space between the opposed crust wall portions, and including the further steps of:
after forming the microporous plate, closing the filling opening of the mold with a strip formed of the casting mix; detaching the microporous plate from the inner surfaces of the opposed mold walls; opening the mold;
allowing the plate to dry; glazing the water duct and edges of the plate; and heating the plate in an oven.
after forming the microporous plate, closing the filling opening of the mold with a strip formed of the casting mix; detaching the microporous plate from the inner surfaces of the opposed mold walls; opening the mold;
allowing the plate to dry; glazing the water duct and edges of the plate; and heating the plate in an oven.
11. The method of claim 10 wherein the heating step comprises raising the temperature of the oven slowly to a high temperature of about 1320 DEG. C. and maintaining the high temperature for about two hours.
12. The method of claim 11 wherein the heating step has a duration of about 48 hours.
13. The method of claim 1 wherein the casting material from which the crust is formed comprises clay, kaolin, aluminum hydroxide and calcium carbonate.
14. The method of claim 9 wherein said casting material comprises about 20% clay, about 30% kaolin, about 45%
aluminum hydroxide, and about 5% calcium carbonate.
aluminum hydroxide, and about 5% calcium carbonate.
15. The method of claim 14 wherein the casting material is formed of raw material in particulate form, the particles of raw material having an average size of about 0.002 mm.
16. A microporous filter plate comprising:
a pair of opposed suction walls formed of microporous material defining an interior space between them; granular material situated in said interior space between said opposed suction walls; and means for placing said interior space in communication with a negative pressure; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
a pair of opposed suction walls formed of microporous material defining an interior space between them; granular material situated in said interior space between said opposed suction walls; and means for placing said interior space in communication with a negative pressure; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
17. The combination of claim 16 where said means for placing said interior space in communication with a negative pressure includes a duct passing into said interior between said microporous suction walls from outside said plate.
18. The combination of claim 16 wherein said filter plate has a length and a thickness, and wherein the ratio of the length to the thickness of the filter plate is greater than about 30.
19. The combination of claim 16 wherein each suction wall has a length and a thickness, and wherein the ratio of the length to the thickness of the suction wall is greater than about 120.
20. Suction drier apparatus, comprising:
at least one filter plate formed of a pair of opposed suction walls formed of microporous material defining an interior space between them and granular material situated in said interior space between said opposed suction walls; means on which said at least one filter plate is mounted for moving said filter plate into and out of a basin or the like in which material to be dewatered is present; and means for reducing the pressure within said interior space of said filter plate to a negative pressure to remove water from the material being dewatered through said suction walls into said interior space.
at least one filter plate formed of a pair of opposed suction walls formed of microporous material defining an interior space between them and granular material situated in said interior space between said opposed suction walls; means on which said at least one filter plate is mounted for moving said filter plate into and out of a basin or the like in which material to be dewatered is present; and means for reducing the pressure within said interior space of said filter plate to a negative pressure to remove water from the material being dewatered through said suction walls into said interior space.
21. The combination of claim 20 wherein said suction drier apparatus comprises a plurality of said filter plates mounted in a circular array connected to a rotatably mounted shaft so that each filter plate is lowered into and then raised from said basin or the like, and a suction tube associated with said shaft and communicating with the interiors of said filter plates.
22. The combination of claim 21 wherein each filter plate includes a duct communicating with said suction tube such that the pressure in said interior space of said filter plate is reduced by applying suction to said suction tube thereby applying a negative pressure to said suction walls of said filter plates whereby water is suctioned from said material being dewatered through said suction walls into said interior spaces and further out of each plate through said duct.
23. The combination of claim 21 wherein the material being dewatered adheres under the force of suction to each said filter plate as each said filter plate is raised out of said basin or the like so that dewatering of said material continues, and further including means for removing the material being dewatered from each filter plate as each filter plate reaches a certain position.
24. The combination of claim 23 wherein said means for removing the material to be dewatered from said filter plates comprises scraper blades.
25. A microporous filter plate comprising:
a pair of opposed suction walls formed of microporous material defining an interior space between them, said suction walls being formed of a mix comprising clay, kaolin, aluminum hydroxide and calcium carbonate; and granular material situated in said interior space between said opposed suction walls; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
a pair of opposed suction walls formed of microporous material defining an interior space between them, said suction walls being formed of a mix comprising clay, kaolin, aluminum hydroxide and calcium carbonate; and granular material situated in said interior space between said opposed suction walls; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
26. A microporous filter plate comprising:
a pair of opposed suction walls formed of microporous material defining an interior space between them; and granular material situated in said interior space between said opposed suction walls, said granular material being formed of the same material as the material of which said suction walls are formed; whereby said filter plate is adapted to brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
a pair of opposed suction walls formed of microporous material defining an interior space between them; and granular material situated in said interior space between said opposed suction walls, said granular material being formed of the same material as the material of which said suction walls are formed; whereby said filter plate is adapted to brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
27. The combination of claim 25 wherein said suction walls are formed of a mix comprising about 20% clay, about 30% kaolin, about 45% aluminum hydroxide and about 5% calcium carbonate.
28. The combination of claim 16, wherein said granular material comprises a ceramic material.
29. The combination of claim 16, wherein said granular material does not present a major resistance to liquid flow in said interior space.
30. The combination of claim 16, wherein said granular material does not prevent suctioning of liquid from said interior space, but acts to reinforce the structure of said plate.
31. The combination of claim 26, wherein said granular material comprises a ceramic material.
32. The combination of claim 28, wherein said suction walls are formed of ceramic material.
33. A microporous filter plate comprising:
a pair of opposed suction walls formed of microporous material defining an interior space between them; granular material situated in said interior space between said opposed suction wall; and means for placing said interior space in communication with a negative pressure; wherein said filter plate in finished form comprises a composition of about 55%
aluminum hydroxide, about 40% silicon dioxide, and about 5%
calcium oxide; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
a pair of opposed suction walls formed of microporous material defining an interior space between them; granular material situated in said interior space between said opposed suction wall; and means for placing said interior space in communication with a negative pressure; wherein said filter plate in finished form comprises a composition of about 55%
aluminum hydroxide, about 40% silicon dioxide, and about 5%
calcium oxide; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
34. A microporous filter plate comprising:
a pair of opposed suction walls formed of microporous material defining an interior space between them; granular material situated in said interior space between said opposed suction walls; and means for placing said interior space in communication with a negative pressure; wherein particles of said granular material have an average size in the range of between about 0.0010 and 0.0015 mm; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
a pair of opposed suction walls formed of microporous material defining an interior space between them; granular material situated in said interior space between said opposed suction walls; and means for placing said interior space in communication with a negative pressure; wherein particles of said granular material have an average size in the range of between about 0.0010 and 0.0015 mm; whereby said filter plate is adapted to be brought into association with material to be dewatered, liquid from the material flowing from the material through said microporous suction walls into said interior space and then out from said interior space.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000524545A CA1316462C (en) | 1986-12-04 | 1986-12-04 | Method for the manufacture of plates, filter plate, and suction drier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000524545A CA1316462C (en) | 1986-12-04 | 1986-12-04 | Method for the manufacture of plates, filter plate, and suction drier |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1316462C true CA1316462C (en) | 1993-04-20 |
Family
ID=4134488
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000524545A Expired - Lifetime CA1316462C (en) | 1986-12-04 | 1986-12-04 | Method for the manufacture of plates, filter plate, and suction drier |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1316462C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115025528A (en) * | 2022-06-13 | 2022-09-09 | 杨英健 | Water-based ink printing wastewater recovery device |
-
1986
- 1986-12-04 CA CA000524545A patent/CA1316462C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115025528A (en) * | 2022-06-13 | 2022-09-09 | 杨英健 | Water-based ink printing wastewater recovery device |
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