CA1247147A - Highly porous ceramic materials for ad- or absorption purposes, more particularly for animal litter, and methods for their production - Google Patents
Highly porous ceramic materials for ad- or absorption purposes, more particularly for animal litter, and methods for their productionInfo
- Publication number
- CA1247147A CA1247147A CA000477525A CA477525A CA1247147A CA 1247147 A CA1247147 A CA 1247147A CA 000477525 A CA000477525 A CA 000477525A CA 477525 A CA477525 A CA 477525A CA 1247147 A CA1247147 A CA 1247147A
- Authority
- CA
- Canada
- Prior art keywords
- clay
- process according
- weight
- temperature
- parts
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims abstract description 27
- 229910010293 ceramic material Inorganic materials 0.000 title claims abstract description 10
- 238000010521 absorption reaction Methods 0.000 title claims abstract description 7
- 238000004519 manufacturing process Methods 0.000 title abstract description 5
- 239000004927 clay Substances 0.000 claims abstract description 34
- 239000000203 mixture Substances 0.000 claims abstract description 20
- 238000010304 firing Methods 0.000 claims abstract description 11
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 10
- 239000000654 additive Substances 0.000 claims abstract description 9
- 230000000996 additive effect Effects 0.000 claims abstract description 6
- 238000000465 moulding Methods 0.000 claims description 11
- 239000000725 suspension Substances 0.000 claims description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 8
- 239000006260 foam Substances 0.000 claims description 7
- 239000004094 surface-active agent Substances 0.000 claims description 7
- 230000009974 thixotropic effect Effects 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 5
- 239000005995 Aluminium silicate Substances 0.000 claims description 4
- 239000002250 absorbent Substances 0.000 claims description 4
- 230000002745 absorbent Effects 0.000 claims description 4
- 235000012211 aluminium silicate Nutrition 0.000 claims description 4
- 239000000440 bentonite Substances 0.000 claims description 4
- 229910000278 bentonite Inorganic materials 0.000 claims description 4
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims description 4
- 238000005187 foaming Methods 0.000 claims description 4
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 claims description 4
- 238000012216 screening Methods 0.000 claims description 4
- 229910052572 stoneware Inorganic materials 0.000 claims description 4
- 239000006004 Quartz sand Substances 0.000 claims description 3
- 239000004113 Sepiolite Substances 0.000 claims description 3
- 239000002253 acid Substances 0.000 claims description 3
- 239000011449 brick Substances 0.000 claims description 3
- 239000011368 organic material Substances 0.000 claims description 3
- 229910052624 sepiolite Inorganic materials 0.000 claims description 3
- 235000019355 sepiolite Nutrition 0.000 claims description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical group Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 2
- -1 calcspar Chemical compound 0.000 claims description 2
- 239000003245 coal Substances 0.000 claims description 2
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 claims description 2
- 239000010459 dolomite Substances 0.000 claims description 2
- 229910000514 dolomite Inorganic materials 0.000 claims description 2
- 239000000428 dust Substances 0.000 claims description 2
- 239000010433 feldspar Substances 0.000 claims description 2
- 229910052901 montmorillonite Inorganic materials 0.000 claims description 2
- 239000011148 porous material Substances 0.000 claims description 2
- 239000003463 adsorbent Substances 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 24
- 125000000129 anionic group Chemical group 0.000 abstract description 2
- 239000003945 anionic surfactant Substances 0.000 abstract description 2
- 239000003093 cationic surfactant Substances 0.000 abstract description 2
- 239000008187 granular material Substances 0.000 description 5
- 239000007788 liquid Substances 0.000 description 4
- 239000000378 calcium silicate Substances 0.000 description 3
- 235000012241 calcium silicate Nutrition 0.000 description 3
- 229960003340 calcium silicate Drugs 0.000 description 3
- 229910052918 calcium silicate Inorganic materials 0.000 description 3
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 230000001877 deodorizing effect Effects 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000007853 buffer solution Substances 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 1
- 239000000292 calcium oxide Substances 0.000 description 1
- 235000012255 calcium oxide Nutrition 0.000 description 1
- 229940087373 calcium oxide Drugs 0.000 description 1
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- BUACSMWVFUNQET-UHFFFAOYSA-H dialuminum;trisulfate;hydrate Chemical compound O.[Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O BUACSMWVFUNQET-UHFFFAOYSA-H 0.000 description 1
- 238000010981 drying operation Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 235000013312 flour Nutrition 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 239000011147 inorganic material Substances 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 235000014380 magnesium carbonate Nutrition 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 235000019353 potassium silicate Nutrition 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229960001866 silicon dioxide Drugs 0.000 description 1
- 235000019830 sodium polyphosphate Nutrition 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- DAJSVUQLFFJUSX-UHFFFAOYSA-M sodium;dodecane-1-sulfonate Chemical compound [Na+].CCCCCCCCCCCCS([O-])(=O)=O DAJSVUQLFFJUSX-UHFFFAOYSA-M 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01C—RESISTORS
- H01C10/00—Adjustable resistors
- H01C10/30—Adjustable resistors the contact sliding along resistive element
- H01C10/32—Adjustable resistors the contact sliding along resistive element the contact moving in an arcuate path
- H01C10/36—Adjustable resistors the contact sliding along resistive element the contact moving in an arcuate path structurally combined with switching arrangements
- H01C10/363—Adjustable resistors the contact sliding along resistive element the contact moving in an arcuate path structurally combined with switching arrangements by axial movement of the spindle, e.g. pull-push switch
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H25/00—Switches with compound movement of handle or other operating part
- H01H25/06—Operating part movable both angularly and rectilinearly, the rectilinear movement being along the axis of angular movement
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Adjustable Resistors (AREA)
- Rotary Switch, Piano Key Switch, And Lever Switch (AREA)
- Porous Artificial Stone Or Porous Ceramic Products (AREA)
- Compositions Of Oxide Ceramics (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)
Abstract
ABSTRACT
The invention provides highly porous ceramic materials for ad- or absorption purposes, more particularly for animal litter, characterized by a porosity of 50 to 300 vol. per cent, preferably 200 to 250 vol. per cent; a water-absorbing capacity of 50 to 200, preferably 100 to 150%, a pH value of between 5 and 9, preferably between 7 and 8, a bulk-density of 400 to 700 g/l; an internal surface (BET (N2)) of between 20 and 200, preferably between 80 and 150 m2/g, the material being produced by firing a foamed mixture of clay(s), if necessary additive(s), anionic or cationic surfactant(s), and deflocculating agent(s); the invention also provides methods for their production.
The invention provides highly porous ceramic materials for ad- or absorption purposes, more particularly for animal litter, characterized by a porosity of 50 to 300 vol. per cent, preferably 200 to 250 vol. per cent; a water-absorbing capacity of 50 to 200, preferably 100 to 150%, a pH value of between 5 and 9, preferably between 7 and 8, a bulk-density of 400 to 700 g/l; an internal surface (BET (N2)) of between 20 and 200, preferably between 80 and 150 m2/g, the material being produced by firing a foamed mixture of clay(s), if necessary additive(s), anionic or cationic surfactant(s), and deflocculating agent(s); the invention also provides methods for their production.
Description
~2~7~4~
The invention relates to highly porous ceramic material for ad- or absorption purposes, more particularly for animal litter and to methods for its production.
There is a constant need for highly porous, rot-proof materials for the ad- or absorption of liquids and gases, but more particularly for use as animal litter.
Calcium-silicate granules have hitherto been used, among other things, with advantage for this purpose, as has been described, for example in European Patents Nos. 00 13 935 and 00 14 343, and in German Patents Nos. 31 21 403 and 29 02 079.
The advantage of the known calcium-silicate granular material is that it has a microporous structure which, because of its capillary action, is capable of absorbing oleophilic and hydrophilic liquids, and also of taking up gaseous substances~
The known calcium-silicate granular material, with its microporous structure is made from a inely ground, silicon-dioxide-containing material such as quartz flour, with the addition of an anion-active, surfactant substance, e.g. Tensid (trade mark), mixed initimately with a calcium-oxide-containing material, such as lime, and water, the mixture then being foamed. This is followed by autoclave hardening~ crushing, grading, final drying and cooling, if necessary. These absorbents, produced according to these known methods have been outstandingly successful in practice.
It is the purpose of the present invention to provide a material for ad- or absorption purposes, more particularly for use as animal litter, which will exhibit the satisfactory , -~,f, ~Z~J~
properties of the known material described hereinbefore, but can be produced less expensively, with a wider variety of product parameters, especially as regards appearance, and in a continuous operation.
According to the invention, this purpose is achieved by means of highly porous ceramic material characterized by a porosity of 50 to 300 vol. per cent, preferably 200 to 250 vol.
per cent, a water-absorbing capacity of 50 to 200, preferably 100 to 150%, a pH value oE between 5 and 9, preferably between 7 and 8, a bulk-density of 400 to 700 g/l, an lnternal surface (BET (~)) of between 20 and 200, preferably between 80 and 150 m /g; produced by firing a foamed mixture of clay(s), if necessary additive(s), anionic or cationic surfactant(s) deflocculating agent~s).
The method according to the invention for producing such ceramic materials is characterized by mixing from 45 to 80 parts by weight of clay, 0 to 50 parts by weight of an additive with a high specific surface, 15 to 30 parts by weight of water, and 0.01 to 0.03 parts by weight of a deflocculating agent; by adding a surfactant and producing a foamed mixture; by moulding and drying the foamed mixture into dried clay mouldings; by crushing the dried clay mouldings; by screening the crushed clay mouldings and preferably returning the fines to the initial mixture; and by firing the crushed clay mouldings, of a selected grain-size range, at a product-temperature of between 600C and 1000C, preferably between 700C and 800C.
In this connection, it is particularly advantageous to use, as additives, inorganic or organic materials with a high ~71~L~
specific surface, for example kiese]guhr, calc-spar, quartz sand, dolomite, feldspar, fireclay, sepiolite, bentonite and/or organic materials such as wood-dust or coal.
The method according to the invention makes it possible to produce, very economically, highly porous ceramic products with porosities in excess of 100%, preferably between 200 and 250~, with pore-size and -type largely controllable.
One advantage is that the time between preparing the clay and obtaining the fired product, with porosities in excess of 100%, is up to two hours or less, mainly because of the short drying and firing times.
Specific methods according to the invention usually involve stirring the clay with water into a thixotropic suspension conta-ining little water. This suspension can be produced with specific amounts of foam preferably having a litre-weight of 30 to 80 g~l. Another method of making a foamed suspension from a clay-suspension consists in adding the surfactant to the clay-suspension and carrying out the foaming in a dispersing unit with the addition of compressed air It is possible to use, for this purpose, conventional dispersing units, as sold, for example by the firm Hansa-Mixer, of 8remen, undex the trads mark ~Hansa-Mixer~, which add specific amounts of compressed air to the mixture under pressure (1 to 10 bars).
The said dispersing unit comprises a precision-metering pump by means of which liquid can be added before and, if necessary, during the foaming process. In carrying out the method according to the invention, it is advantageous to use a substance which counteracts the deflocculating agent, for .. . . .. . . ... ..... . . ........ ..
7~4~
example dilute hydrochloric acid, since this makes it possible to produce highly viscous, thixotropic, inherently stable foam-suspensions.
The inherently stable, thixotropic foam suspension is then dried, it being possible for the water-vapour to escape relatively freely through the pores because of the high inherent porosity of the material. In this connection, it is particularly beneficial for the initial mixture to have a relatively low water-content. The dried material is normally obtained in lengths of about.l cm in diameter, the operation being carried out at temperatures of 200C, with drying times of not more than 5 minutes, for example. This dried material is crushed into granules prior to firing.
Like the drying operation, the firing operation is very favourable because of the porosity of the material. At a furnace-temperature of 1000C, corresponding to a material-temperature of between 600C and 800C, it is possible to produce, with a firing time of less than 5 minutes, including heating-up and cooling-down, porous granular material particularly suitable for use as animal litter. During this heat-treatment~ the clays are compacted to such an e~tent that they become insoluble in water.
If the material according to the invention is to be used as an absorbent, or as animal litter, treatment at a higher temperature is not desirable, since this causes the material to become brittle and reduces its internal surface. Because of the hard fracture-surfaces arising from embrittlement, and the ~7~
reduction in the internal surface, the capacity to absorb liquid is undesirably impaired.
Because of its large internal surface, the material produced according to the invention, and fired at low temperatures, has a strong deodorizing action and good water-absorbing capacity.
Another advantage is that the porous ceramic elements of the material are chemically neutral, the pH value thereof being between 5 and 8. In one particularly preferred application of the ad- or absorbent material according to the invention as animal litter, it may be desirable to stabilize the pH value, for example, by treatment with an acid or an acid-salt, in order to ensure that the pH remains between 5 and 8, since this is particularly effective in deodorizing basic constituents.
Finally, it is proposed, according to a specific aspect of the invention, that the entire operation for producing the material of the invention be carried out continuously.
The invention also relates to the use of the ceramic material elements, in solid and/or granular form, as a heat-and/or noise-insulating material for building purposes, and the use of the ceramic material elements, in solid and/or granular form, as an additive for high-temperature structural materials such as furnace materials, refractory materials, and the like.
In the production of refractory building materials for example, the usual additives will, of course be used in appropriate amounts, for example magnesite, quartz sand, and the like, as required by the particular application.
~ILZ~7~
The materials of the invention may be characterised in that the mixture contains between 45 and 80, preferably between 60 and 75 parts by weight o~ clay, 15 to 30, preferably 15 to 20 parts by weight of water, 0 to 50, preferably between 10 and 20 parts by weight of an additive with high specific surface, 0.001 to 0.01 parts by weight of a surfactant, and 0.01 to 0.03 parts by weight of a deflocculating agent. They may also be characterized in that the following are used as clay: brick clay, Westerwalder stoneware clay, fine stoneware clay, kaolin, montmorillonite, bentonite or marl.
The methods of the invention may also be characterized in that the foamed mixture is produced by adding 0.01 to 0.001 parts by weight of surfactant to the initial mixture and foaming this in a dispersing unit known under pressure (1 to 10 bars), with a feed of compressed air, between ambient temperature and 95C, it being possible to use, if necessary, agents opposing the deflocculating agent, in order to produce a highly viscous, thixotropic, inherently stable foamed suspension.
The method may further be characterized in that the finished foam, having a litre-weight of between 30 and ~0 g/l, is mixed with the clay mixture, the surfactant content of the foamed mass amounting to about OoO01 to 0.01 by weight.
The method may further be characterized in that drying of the clay elements is carried out at a temperature between room-temperature and 200C.
The method may further be characterized in that firing is carried out in less than 5 minutes at a furnace-temperature 3.Z~i7~
of less than 1000C, corresponding to a product-temperature of between 600 and 800C.
The method may further be characterized in that the fired , highly porousr ceramic material i5 treated with an acid or an acid-salt in such a manner that the pH value thereof lies between 5 and 8 after the treatment.
The method may further be characterized in that the acid treatment is carried out in a spray-drum or the like and/or the conduct of the whole process is substantially continuous.
Further characteristics and advantages of the invention may be gathered from the following description in which specific embodiments are explained in detail in conjunction with the diagram attached hereto.
The said drawing, consisting of a single figure, shows a flow chart of the method according to the invention.
Example I
500 kg of brick clay are placed, with 200 litres of water, 400 kg of kieselguhr, 100 g of sodium polyphosphate, 100 g of sodium dodecyl-sulphonate, and 5 kg of returned foamed-clay fines, in a mixer; this is stirred vigorously for about 5 minutes and the resulting, highly thixotropic clay-suspension is placed in a forming unit; the resulting lengths, about 1 cm in diameter, are placed in a rotary drier, preheated to 200C, which, after a drying time of 5 minutes, passes the foamed-clay material to a roller-crusher in which it is crushed. The crushed particles of foamed clay are then separated in a screening unit, one fraction having a grain-size of between 2.5 ~z'~
and 4 mm, which passes to the firing Eurnace~ and the other fraction having a grain-size of less than 2.5 mm which is returned to the initial mixture. The dried, foamed-clay particles to be fired enter into a continuously operating furnace heated to 1000C in which they are fired for a period of 5 minutes. The fired ceramic product is cooled and passed to a packaging unit.
EXAMPLE I I
800 kg of kaolin, 200 litres of water, and 200 kg of sepiolite are thoroughly mixed in a mixer with 50 g of water-glass. This mixture is delivered continuously to a second mixer which has an additional feed for a "Hostapur" (Trade Mark of Hoechst A.C. ) foam having a litre-weight of 50 g/1, thus maintaining a constant ratio of about 100 g of hostapur foam per 800 g of kaolin. The resulting foamed-clay-suspension mix is then compressed with a forming tool, thus producing lengths measuring 1.5 cm in diameter. These lengths of formed clay are allowed to dry at room temperature. The dried lengths are crushed in a crusher and passed to a screening unit where the fraction of crushed material which is less than l mm in diameter is returned to the initial mixture, whereas the remaining particles are passed to a furnace operating at a temperature of 800C. The crushed and dried, foamed-clay particles are fired in the furnace for lO minutes. The resulting porous product is cooled and passed to a spray-drum where it is treated with a mixture of 31% by weight of 85% phosphoric acid and 69% by we ght of an aluminum-sulphate solution having a pH value of 2 4~
to 3.5 and a density of 1.3 to 1.34. The material, sprayed with a buffer-solution, is then dried again and passed to a packaging unit.
The materials according to the invention are noted, for example, for the following material characteristics.
pH value: 7 - 8 water-absorbing capacity: 50 to 150% by weight internal surface 20 m2~g _ 200 m2/g pore-diameter 1 mm.
The invention relates to highly porous ceramic material for ad- or absorption purposes, more particularly for animal litter and to methods for its production.
There is a constant need for highly porous, rot-proof materials for the ad- or absorption of liquids and gases, but more particularly for use as animal litter.
Calcium-silicate granules have hitherto been used, among other things, with advantage for this purpose, as has been described, for example in European Patents Nos. 00 13 935 and 00 14 343, and in German Patents Nos. 31 21 403 and 29 02 079.
The advantage of the known calcium-silicate granular material is that it has a microporous structure which, because of its capillary action, is capable of absorbing oleophilic and hydrophilic liquids, and also of taking up gaseous substances~
The known calcium-silicate granular material, with its microporous structure is made from a inely ground, silicon-dioxide-containing material such as quartz flour, with the addition of an anion-active, surfactant substance, e.g. Tensid (trade mark), mixed initimately with a calcium-oxide-containing material, such as lime, and water, the mixture then being foamed. This is followed by autoclave hardening~ crushing, grading, final drying and cooling, if necessary. These absorbents, produced according to these known methods have been outstandingly successful in practice.
It is the purpose of the present invention to provide a material for ad- or absorption purposes, more particularly for use as animal litter, which will exhibit the satisfactory , -~,f, ~Z~J~
properties of the known material described hereinbefore, but can be produced less expensively, with a wider variety of product parameters, especially as regards appearance, and in a continuous operation.
According to the invention, this purpose is achieved by means of highly porous ceramic material characterized by a porosity of 50 to 300 vol. per cent, preferably 200 to 250 vol.
per cent, a water-absorbing capacity of 50 to 200, preferably 100 to 150%, a pH value oE between 5 and 9, preferably between 7 and 8, a bulk-density of 400 to 700 g/l, an lnternal surface (BET (~)) of between 20 and 200, preferably between 80 and 150 m /g; produced by firing a foamed mixture of clay(s), if necessary additive(s), anionic or cationic surfactant(s) deflocculating agent~s).
The method according to the invention for producing such ceramic materials is characterized by mixing from 45 to 80 parts by weight of clay, 0 to 50 parts by weight of an additive with a high specific surface, 15 to 30 parts by weight of water, and 0.01 to 0.03 parts by weight of a deflocculating agent; by adding a surfactant and producing a foamed mixture; by moulding and drying the foamed mixture into dried clay mouldings; by crushing the dried clay mouldings; by screening the crushed clay mouldings and preferably returning the fines to the initial mixture; and by firing the crushed clay mouldings, of a selected grain-size range, at a product-temperature of between 600C and 1000C, preferably between 700C and 800C.
In this connection, it is particularly advantageous to use, as additives, inorganic or organic materials with a high ~71~L~
specific surface, for example kiese]guhr, calc-spar, quartz sand, dolomite, feldspar, fireclay, sepiolite, bentonite and/or organic materials such as wood-dust or coal.
The method according to the invention makes it possible to produce, very economically, highly porous ceramic products with porosities in excess of 100%, preferably between 200 and 250~, with pore-size and -type largely controllable.
One advantage is that the time between preparing the clay and obtaining the fired product, with porosities in excess of 100%, is up to two hours or less, mainly because of the short drying and firing times.
Specific methods according to the invention usually involve stirring the clay with water into a thixotropic suspension conta-ining little water. This suspension can be produced with specific amounts of foam preferably having a litre-weight of 30 to 80 g~l. Another method of making a foamed suspension from a clay-suspension consists in adding the surfactant to the clay-suspension and carrying out the foaming in a dispersing unit with the addition of compressed air It is possible to use, for this purpose, conventional dispersing units, as sold, for example by the firm Hansa-Mixer, of 8remen, undex the trads mark ~Hansa-Mixer~, which add specific amounts of compressed air to the mixture under pressure (1 to 10 bars).
The said dispersing unit comprises a precision-metering pump by means of which liquid can be added before and, if necessary, during the foaming process. In carrying out the method according to the invention, it is advantageous to use a substance which counteracts the deflocculating agent, for .. . . .. . . ... ..... . . ........ ..
7~4~
example dilute hydrochloric acid, since this makes it possible to produce highly viscous, thixotropic, inherently stable foam-suspensions.
The inherently stable, thixotropic foam suspension is then dried, it being possible for the water-vapour to escape relatively freely through the pores because of the high inherent porosity of the material. In this connection, it is particularly beneficial for the initial mixture to have a relatively low water-content. The dried material is normally obtained in lengths of about.l cm in diameter, the operation being carried out at temperatures of 200C, with drying times of not more than 5 minutes, for example. This dried material is crushed into granules prior to firing.
Like the drying operation, the firing operation is very favourable because of the porosity of the material. At a furnace-temperature of 1000C, corresponding to a material-temperature of between 600C and 800C, it is possible to produce, with a firing time of less than 5 minutes, including heating-up and cooling-down, porous granular material particularly suitable for use as animal litter. During this heat-treatment~ the clays are compacted to such an e~tent that they become insoluble in water.
If the material according to the invention is to be used as an absorbent, or as animal litter, treatment at a higher temperature is not desirable, since this causes the material to become brittle and reduces its internal surface. Because of the hard fracture-surfaces arising from embrittlement, and the ~7~
reduction in the internal surface, the capacity to absorb liquid is undesirably impaired.
Because of its large internal surface, the material produced according to the invention, and fired at low temperatures, has a strong deodorizing action and good water-absorbing capacity.
Another advantage is that the porous ceramic elements of the material are chemically neutral, the pH value thereof being between 5 and 8. In one particularly preferred application of the ad- or absorbent material according to the invention as animal litter, it may be desirable to stabilize the pH value, for example, by treatment with an acid or an acid-salt, in order to ensure that the pH remains between 5 and 8, since this is particularly effective in deodorizing basic constituents.
Finally, it is proposed, according to a specific aspect of the invention, that the entire operation for producing the material of the invention be carried out continuously.
The invention also relates to the use of the ceramic material elements, in solid and/or granular form, as a heat-and/or noise-insulating material for building purposes, and the use of the ceramic material elements, in solid and/or granular form, as an additive for high-temperature structural materials such as furnace materials, refractory materials, and the like.
In the production of refractory building materials for example, the usual additives will, of course be used in appropriate amounts, for example magnesite, quartz sand, and the like, as required by the particular application.
~ILZ~7~
The materials of the invention may be characterised in that the mixture contains between 45 and 80, preferably between 60 and 75 parts by weight o~ clay, 15 to 30, preferably 15 to 20 parts by weight of water, 0 to 50, preferably between 10 and 20 parts by weight of an additive with high specific surface, 0.001 to 0.01 parts by weight of a surfactant, and 0.01 to 0.03 parts by weight of a deflocculating agent. They may also be characterized in that the following are used as clay: brick clay, Westerwalder stoneware clay, fine stoneware clay, kaolin, montmorillonite, bentonite or marl.
The methods of the invention may also be characterized in that the foamed mixture is produced by adding 0.01 to 0.001 parts by weight of surfactant to the initial mixture and foaming this in a dispersing unit known under pressure (1 to 10 bars), with a feed of compressed air, between ambient temperature and 95C, it being possible to use, if necessary, agents opposing the deflocculating agent, in order to produce a highly viscous, thixotropic, inherently stable foamed suspension.
The method may further be characterized in that the finished foam, having a litre-weight of between 30 and ~0 g/l, is mixed with the clay mixture, the surfactant content of the foamed mass amounting to about OoO01 to 0.01 by weight.
The method may further be characterized in that drying of the clay elements is carried out at a temperature between room-temperature and 200C.
The method may further be characterized in that firing is carried out in less than 5 minutes at a furnace-temperature 3.Z~i7~
of less than 1000C, corresponding to a product-temperature of between 600 and 800C.
The method may further be characterized in that the fired , highly porousr ceramic material i5 treated with an acid or an acid-salt in such a manner that the pH value thereof lies between 5 and 8 after the treatment.
The method may further be characterized in that the acid treatment is carried out in a spray-drum or the like and/or the conduct of the whole process is substantially continuous.
Further characteristics and advantages of the invention may be gathered from the following description in which specific embodiments are explained in detail in conjunction with the diagram attached hereto.
The said drawing, consisting of a single figure, shows a flow chart of the method according to the invention.
Example I
500 kg of brick clay are placed, with 200 litres of water, 400 kg of kieselguhr, 100 g of sodium polyphosphate, 100 g of sodium dodecyl-sulphonate, and 5 kg of returned foamed-clay fines, in a mixer; this is stirred vigorously for about 5 minutes and the resulting, highly thixotropic clay-suspension is placed in a forming unit; the resulting lengths, about 1 cm in diameter, are placed in a rotary drier, preheated to 200C, which, after a drying time of 5 minutes, passes the foamed-clay material to a roller-crusher in which it is crushed. The crushed particles of foamed clay are then separated in a screening unit, one fraction having a grain-size of between 2.5 ~z'~
and 4 mm, which passes to the firing Eurnace~ and the other fraction having a grain-size of less than 2.5 mm which is returned to the initial mixture. The dried, foamed-clay particles to be fired enter into a continuously operating furnace heated to 1000C in which they are fired for a period of 5 minutes. The fired ceramic product is cooled and passed to a packaging unit.
EXAMPLE I I
800 kg of kaolin, 200 litres of water, and 200 kg of sepiolite are thoroughly mixed in a mixer with 50 g of water-glass. This mixture is delivered continuously to a second mixer which has an additional feed for a "Hostapur" (Trade Mark of Hoechst A.C. ) foam having a litre-weight of 50 g/1, thus maintaining a constant ratio of about 100 g of hostapur foam per 800 g of kaolin. The resulting foamed-clay-suspension mix is then compressed with a forming tool, thus producing lengths measuring 1.5 cm in diameter. These lengths of formed clay are allowed to dry at room temperature. The dried lengths are crushed in a crusher and passed to a screening unit where the fraction of crushed material which is less than l mm in diameter is returned to the initial mixture, whereas the remaining particles are passed to a furnace operating at a temperature of 800C. The crushed and dried, foamed-clay particles are fired in the furnace for lO minutes. The resulting porous product is cooled and passed to a spray-drum where it is treated with a mixture of 31% by weight of 85% phosphoric acid and 69% by we ght of an aluminum-sulphate solution having a pH value of 2 4~
to 3.5 and a density of 1.3 to 1.34. The material, sprayed with a buffer-solution, is then dried again and passed to a packaging unit.
The materials according to the invention are noted, for example, for the following material characteristics.
pH value: 7 - 8 water-absorbing capacity: 50 to 150% by weight internal surface 20 m2~g _ 200 m2/g pore-diameter 1 mm.
Claims (10)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for producing a porous ceramic material for use as an adsorbent or absorbent, particularly as animal litter, having a porosity of 50 to 300 vol. per cent, a water-absorption capacity of 50 to 200 per cent, a pH value of between 5 and 9, a bulk-density of 400 to 700 g/l, and an internal surface (BET
(N2)) of between 20 and 200 m2/g, which comprises forming a starting mixture containing 45 to 80 parts by weight of clay, 15 to 30 parts by weight of water, 0 to 50 parts by weight of an additive with high specific surface, 0.01 to 0.03 parts by weight of a deflocculating agent and 0.001 to 0.01 parts by weight of a surfactant; foaming the starting mixture under pressure (1 to 10 bar), with a feed of compressed air, between ambient temperature and 95°C to form a foam; moulding and drying the foam into clay mouldings; crushing the dried clay mouldings;
screening the crushed clay mouldings and returning fines to the starting mixture; and firing the crushed clay mouldings, of a selected particle size range, the temperature within the product being betweeen 600 and 1000°C.
(N2)) of between 20 and 200 m2/g, which comprises forming a starting mixture containing 45 to 80 parts by weight of clay, 15 to 30 parts by weight of water, 0 to 50 parts by weight of an additive with high specific surface, 0.01 to 0.03 parts by weight of a deflocculating agent and 0.001 to 0.01 parts by weight of a surfactant; foaming the starting mixture under pressure (1 to 10 bar), with a feed of compressed air, between ambient temperature and 95°C to form a foam; moulding and drying the foam into clay mouldings; crushing the dried clay mouldings;
screening the crushed clay mouldings and returning fines to the starting mixture; and firing the crushed clay mouldings, of a selected particle size range, the temperature within the product being betweeen 600 and 1000°C.
2. The process according to claim 1, wherein the porous material is 200 to 250 vol. per cent, the water-absorption capacity is 100 to 150 per cent, the pH value is between 7 and 8, and the internal surface (BET (N2)) is between 80 and 150 m2/g.
3. The process according to claim 1, wherein the crushed clay mouldings are fired at a temperature within the product between 700 and 800°C.
4. The process according to claim 1, further comprising adding a deflocculant-counteracting agent to produce a highly viscous, thixotropic, inherently stable foamed suspension.
5. The process according to claim 4, wherein the deflocculant-counteracting agent is dilute hydrochloric acid.
6. The process according to claim 1, wherein the drying of the clay elements is carried out at a temperature between ambient temperature and 200°C.
7. The process according to claim 1, wherein the firing is carried out in less than 5 minutes at a furnace temperature of 1000°C, corresponding to a product-temperature of between 600 and 800°C.
8. The process according to claim 1, wherein the fired, highly porous, ceramic material is treated with an acid or and acid-salt in such a manner that the pH value thereof lies between 5 and 8 after the treatment.
9. The process according to claim 1, wherein the following are used as clay: brick clay, Westerwalder stoneware clay, fine stoneware clay, kaolin, montmorillonite, bentonite or marl.
10. The process according to claim 1, wherein the following are used as additives: kieselguhr, calcspar, quartz sand, dolomite, feldspar, fireclay, sepiolite, bentonite, and/or organic materials such as a wood-dust or coal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19843412965 DE3412965A1 (en) | 1984-04-06 | 1984-04-06 | ELECTRICAL COMPONENT |
| DEP3412965.1-45 | 1984-04-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1247147A true CA1247147A (en) | 1988-12-20 |
Family
ID=6232838
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000477525A Expired CA1247147A (en) | 1984-04-06 | 1985-03-26 | Highly porous ceramic materials for ad- or absorption purposes, more particularly for animal litter, and methods for their production |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0157373A3 (en) |
| CA (1) | CA1247147A (en) |
| DE (1) | DE3412965A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3821004A1 (en) * | 1988-06-22 | 1989-12-28 | Thomson Brandt Gmbh | ROTATED ENCODER FOR DIGITAL IMPULSES AND METHOD OF USE THEREOF |
| DE29712121U1 (en) | 1997-07-10 | 1997-09-11 | Sigma Laborzentrifugen Gmbh, 37520 Osterode | Control device for a laboratory centrifuge |
| DE19853587A1 (en) | 1998-11-20 | 2000-05-25 | Fahrzeugklimaregelung Gmbh | Switching device combining rotary potentiometer with push switch e.g. for motor vehicle heating or air conditioning system has push switch arranged inside hollow cylindrical shape of rotary potentiometer |
| DE102004001592B4 (en) * | 2004-01-09 | 2013-11-28 | Endress + Hauser Conducta Gesellschaft für Mess- und Regeltechnik mbH + Co. KG | Rotary switch and field device with such |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2547765A (en) * | 1948-11-05 | 1951-04-03 | W L Maxson Corp | Switch actuator |
| DE931964C (en) * | 1952-04-27 | 1955-08-22 | Preh Elektro Feinmechanik | Rotary resistance, preferably with a rotary switch that can be operated by the same axis of rotation, with an additional switch to be actuated by moving the axis of rotation in length |
| US3413431A (en) * | 1967-06-29 | 1968-11-26 | Stackpole Carbon Co | Snap action slide switch |
| DE7046185U (en) * | 1970-12-15 | 1972-03-23 | Swf Rau G Gmbh | Rotary switches with pushbutton switches, in particular for motor vehicles |
| DE2609166C3 (en) * | 1976-03-05 | 1979-03-08 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Electric adjustment device |
| DE3039346C2 (en) * | 1980-10-17 | 1984-06-07 | Bosch-Siemens Hausgeräte GmbH, 7000 Stuttgart | Arrangement for entering electrically detectable control variables |
| US4363018A (en) * | 1980-11-03 | 1982-12-07 | Matsushita Electric Industrial Co., Ltd. | Electronic components of rotary type |
| US4341934A (en) * | 1980-11-21 | 1982-07-27 | The Keyboard Company | Actuator for keyboard switches |
-
1984
- 1984-04-06 DE DE19843412965 patent/DE3412965A1/en not_active Withdrawn
-
1985
- 1985-03-26 CA CA000477525A patent/CA1247147A/en not_active Expired
- 1985-03-28 EP EP85103756A patent/EP0157373A3/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| EP0157373A2 (en) | 1985-10-09 |
| EP0157373A3 (en) | 1988-12-28 |
| DE3412965A1 (en) | 1985-10-24 |
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