CA1232295A - Method for the production of porous silica granules which have mechanical strength and withstand moisture - Google Patents
Method for the production of porous silica granules which have mechanical strength and withstand moistureInfo
- Publication number
- CA1232295A CA1232295A CA000475469A CA475469A CA1232295A CA 1232295 A CA1232295 A CA 1232295A CA 000475469 A CA000475469 A CA 000475469A CA 475469 A CA475469 A CA 475469A CA 1232295 A CA1232295 A CA 1232295A
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- Prior art keywords
- silica
- granules
- binder
- raw material
- containing raw
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-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
- B01J20/103—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate comprising silica
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- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Analytical Chemistry (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Drying Of Gases (AREA)
Abstract
Abstract The invention relates to a method for the production of porous silica granules which have mechanical strength and withstand the effect of moisture, by granulating a mixture of a finely-ground silica-containing raw material, a binder and water, and by drying and possibly heat-treating the granules thus obtained. In accordance with the invention, the binder used is burnt lime or cement in a minimum amount of 2% of the weight of the silica-containing raw material.
Description
~Z3ZZ9S
A method for the production of porous silica granules which have mechanical strength and withstand moisture The present invention relates to a method for the production of porous silica granules which have mechanical strength and withstand moisture, by granulating a mixture of a finely-ground silica-containing raw material, such as synthetic silica or a silica skeleton separated from a silicate such as phlogopite, of a binder, and of water, and by drying the thus obtained granules. Granules prepared by the method according to the invention are well suited for the production of chemical adsorbent, for example.
Finely-divided materials can be agglomerated, or granulated, in very many different ways, for example by mixing, compression, thermal treatment, by spray and dispersion methods, and by agglomeration from a liquid medium. The joining of small particles to form agglomerates can occur with the help of solid-material bridges, stationary or moving liquids, internal and external forces of molecules, and mechanical bonds. Many kinds of additives can be used for increasing the particle size, such as binders, lubricants, and wetting agents. Only adsorbent having a large internal surface have technical importance. As a result of activation or a special preparation method, a large number of small pores and a large specific surface area can be obtained in the adsorbent. In addition to the surface area, the size of the pores is decisively important. Most of the active surface is within micro pores. The presence of macro pores is important for diffusion velocity, In addition to the surface properties, the mix must fulfill certain technical requirements, especially as regards mechanical strength. The more porous the material is, the more binder it in general requires in order to cohere. A high amount of ~23229~
binder for its part tends to clog the pores in the granule and to decrease its specific surface area.
Synthetic silicas are good aggregates for adsorbent with respect to their chemical and physical properties. They are well resistant to moisture, to changes in temperature and pressure, and to most substances used in adsorption applications. They have a large specific surface area, a high pore volume, and a high micro-meso-macroporosity.
However, for adsorption applications they must first be granulated. The granulating method should be one which affects the porosity of the initial material as little as possible but which at the same time gives sufficient strength to the granules so that they withstand mechanical handling.
The methods presented in the literature for the granulating of silicas are of the kinds which produce either porous but too soft ~ranules,or strong granules which are too dense for adsorption applications. The strength of porous granules can be increased by using more binder; in this case, however, the amount of micro porous adsorbent decreases and its effectiveness is reduced.
In addition to synthetic silica, a silica skeleton separated from a silicate has a pore distribution suitable for adsorption applications. However, it is necessary to use a binder in granulating it in order for the granules to obtain a mechanical strength sufficient for their further use. The literature presents different methods for the preparation of silica granules, but they have been found unsuitable for adsorption applications, mainly for the following reasons:
binders (e.g. lye, water-glass and starch) by means of which sufficiently strong granules were obtained either - significantly decreased the specific surface area of the 123229~
silica (lye, water-glass) and thereby decreased the usability of the granules for adsorption applications, or - the binder (starch) itself acted on the chemicals used for the impregnation of adsorption mixes (starch is a reducer), thereby limiting the possibilities for use of the product. The reducing action of starch can, it is true, be eliminated by thermal treatment, but then the preparation costs of the product also increase.
By using binders which did not decisively alter the porosity of the initial product (for example silica sol), sufficiently strong granules were obtained only when binder had been used at over 10 % of the weight of silica. Even then the resistance of the granules to abrasion was not sufficiently high. The costs of the binder also rose too high.
The object of the present invention is therefore to provide an economical method for the preparation of silica granules which are at the same time both very porous and have mechanical strength and withstand moisture. The object of the invention is in particular to provide a method for the preparation of silica structures suitable for adsorption mixes.
The main characteristics of the invention are given in the accompanying claims.
It has now been observed surprisingly that by using burnt lime and/or cement as the binder it is possible to obtain from a finely-ground silica-containing raw material, such as synthetic silica and a silica skeleton separated from a silicate such as phlogo~ite, very porous silica granules which are at the same time mechanically very strong and withstand moistening.
,, ~23229~
Burnt lime and/or cement is added at 2 % at minimum, preferably at approximately Lowe I, calculated from the weight of the silica-containing raw material.
It has been observed in particular that by using burnt lime as the binder it is possible to granulate from silica, for example by means of a tray granulator, porous spherical granules which withstand mechanical handling well, in such a manner that the specific surface area of the silica being granulated does not change to a noteworthy degree. When the granulation is carried out from a paste, cement can advantageously be used as a binder besides, or instead of, burnt lime. This procedure it an especially advantageous alternative when the silica is not dried but the granulation is carried out from a slurry or a filter-dry cake. Tray granulation is suitable above all for dried silica.
With respect to the strength of the granules it is important that they are allowed to prudery slowly in the presence of air, for example for 1-2 days at approximately room temperature. The result is further improved if the redrying is carried out in air which contains carbon dioxide. The final drying can be carried out at elevated temperature by keeping the granules, for example, for 1-2 hours at above lo C, preferably at Lowe C. Thereby the impregnability of the granules is maximized.
By the method according to the invention it is possible to prepare granules which are well suited for adsorption applications for example. The desired pore and strength properties have been achieved without chancing the original advantageous properties of the silica. The mechanical strength of the prepared granules is, in addition, so high that they can be used for air purification applications. In addition, the granules give off very little dust.
lZ3229S
The invention is described below in greater detail with the aid of examples.
Reference Example 1 A silica sol having a dry matter content of 15 by weight was added to 25 g dried and ground silica skeleton separated from phlogopite, in such an amount that the silica sol content of the mix, calculated as dry matter, was a) 5, b) 10, c) 15, d) 20 and e) 30 of the weight of the silica.
When necessary, water was added to the mixture in such an amount that a suitably moist paste was obtained (water approximately 60 % by weight).
my using a perforated plate, cylindrical granules (diameter 3 mm, height 4 mm) were formed from the mixes, and the granules were dried first for a few days at room temperature, then overnight at 110 C. The specific surface area of the prepared granules was determined by N2-adsorption (BET).
The resistance of the granules to compression and abrasion was checked by the hand.
Granules which contained dry matter of silica sol at most 10 % of the weight of silica fractured easily when pressed.
Their surface gave off a large amount of dust when they were chosen. When the binder amounted to more than 10 % of the weight of silica, the resistance of the granules to compression was relatively good but their resistance to abrasion continued to be poor. The BET surface area of the granules decreased when the amount of binder increased from 205 mug to 110 mug corresponding to 5 % and 30 % silica sol as dry matter of the weight of silica.
Reference Example 2 1.25 g starch was mixed with 100 g silica slurry having a solids content of 25 percent by weight. While mixing by Jo ~23Z295 means of a magnetic mixer the temperature was raised close to 100 C, at which time the mixture converted to a Mel. By means ox a perforated plate cylindrical pieces (diameter 3 mm, height 4 mm) were formed from the cooled mix. The granules were dried first at room temperature, then at 110 C. The resistance of the granules to compression and abrasion was checked by the hand. The specific surface area was determined by N2-adsorption (BET).
When pressed, the granules felt strong and, when they were shaken, they gave off very little dust. Their BET surface area was 310 mug When the granules prepared in the above manner were impregnated with a KMnO4 solution, the starch used as the binder reduced the permanganate to manganese dioxide. At this time a significant proportion of the effectiveness of the mix intended for adsorption applications was lost. The reducing action of the starch was almost completely eliminated when the granules were heat treated at 500 C.
Reference Example 3 12.5, 35.5, 72.6 and 126 ml 2-N Noah solution were added to 150 g moist silica (HO 65 % by weight). The mix was stirred well and dried to produce a moldable paste.
Cylindrical pieces (diameter 3 mm, height 4 mm) were prepared from the paste by means of a perforated plate. The pieces were dried at 110 C, and the resistance of the thus obtained granules to abrasion and compression was evaluated by the hand. Their specific surface area was determined by N2-adsorption. The results are shown in Table 1 below.
lZ32Z9~i Table l ON Wash solution BET Strength ml N go a) 12.5 205 Brittle, crumbled easily b) 35.5 110 " " "
c) 72.6 25 Relatively strong, did not give off dust d) 125 I Strong, did not give off dust A similar decrease in the surface area and a similar improvement in strength were observable when corresponding sodium additions were made in the form of water-glass. In this case, a water-glass solution was used which had a dry matter content of 25 % by weight and Sue : NATO = 2.5 (molar ratio).
Example 4 Finely-ground burnt lime at 5 % by weight was added to finely-ground silica. This mixture was fed onto a rotating granulating tray while water was sprayed onto it. The granulation conditions were adjusted in such a way that a maximum number of granules having a size of 2-5 mm was obtained. The granules were dried at room temperature in the presence of air for 1-2 days and finally at 105 C for about 2 hours.
The pore distribution of the granules thus prepared and their specific surface area were analyzed both by using a Hug porosimeter and by nitrogen adsorption. By using a Hug porosimeter the surface area obtained was 158 mug and the pore volume 1.38 ml/g, and respectively by N2-adsorption the surface area obtained was 149 m go When felt by the hand the granules were strong, and when they were screened, very little dust detached from them. The granules were ~Z3ZZ9S
impregnated with a KMnO4 solution. No changes were observed in the strength of the granules. It should be pointed out that, when granules had been prepared from both natural silicates and from synthetic silicates, by using burnt lime as the binder, the granules broke during impregnation.
Reference Example 5 Finely-ground cement was mixed at 5 %, calculated from the weight of the silica, with an aqueous slurry of a wet-ground silica skeleton of phlogopite. The tough paste thus obtained was formed into cylindrical pieces (diameter 3 mm, height 3-5 mm) by means of an extruder-type granulator. The granules were first dried in the presence of air for 2 days at room temperature and thereafter for 2 hours at 110 C.
The pore distribution and specific surface area of the granules prepared in this manner were analyzed both by means of a Hug porosimeter and by nitrogen adsorption. A surface area of 70 mug and a pore volume of 1.06 ml/g were obtained by means of a Hug porosimeter and respectively a surface area of 220 m go by nitrogen adsorption. When felt by the hand the granules were found to be even stronger than those prepared in Example 4. Their resistance to impregnation was also good. Cement-bonded silicate granules did not withstand moistening.
The pore size distributions of the granules prepared in Examples 4 and 5 are shown graphically in Figure 1.
The difference between the surface areas measured by nitrogen adsorption and a Hug porosimeter describes the micro porosity of the product. The granules prepared by the method according to the invention differ from commercial adsorbent above all with respect to Marco porosity (pore diameter over 200 no).
The MicroPro volume of commercial adsorbent (for example 123229~
XMnO4-impregnated Allah mixes presented in US. Patent 3,226,332) is only 10-30 % of the macro porosity of granules prepared by the method according to the present invention.
The pore volume of granules intended as adsorption mixes is important both for their action and for their impregnability (the higher the pore volume, the more impregnation liquid can be caused to be absorbed into the granules). Those properties of granules prepared by the methods described in the examples above which are crucial with respect to adsorption applications have been compiled into Table 2.
Table 2 Resistance to Resistance to Specific Pore Suitability compression abrasion surface volume for adsorbing M go ml/g mixes Reference example l a) poor poor 205 no b) good poor 110 no " 2 good good 310 xx)no " 3 a) poor poor 110 xxx)no b) good good I xxxx)no Example 4 good good 173 1.32 yes " 5 good good 220 1.03 "
x) binder costs too high, resistance to abrasion poor xx) reducing properties of starch are . hindrance xxx) mechanical resistance poor xxxx) surface area too small
A method for the production of porous silica granules which have mechanical strength and withstand moisture The present invention relates to a method for the production of porous silica granules which have mechanical strength and withstand moisture, by granulating a mixture of a finely-ground silica-containing raw material, such as synthetic silica or a silica skeleton separated from a silicate such as phlogopite, of a binder, and of water, and by drying the thus obtained granules. Granules prepared by the method according to the invention are well suited for the production of chemical adsorbent, for example.
Finely-divided materials can be agglomerated, or granulated, in very many different ways, for example by mixing, compression, thermal treatment, by spray and dispersion methods, and by agglomeration from a liquid medium. The joining of small particles to form agglomerates can occur with the help of solid-material bridges, stationary or moving liquids, internal and external forces of molecules, and mechanical bonds. Many kinds of additives can be used for increasing the particle size, such as binders, lubricants, and wetting agents. Only adsorbent having a large internal surface have technical importance. As a result of activation or a special preparation method, a large number of small pores and a large specific surface area can be obtained in the adsorbent. In addition to the surface area, the size of the pores is decisively important. Most of the active surface is within micro pores. The presence of macro pores is important for diffusion velocity, In addition to the surface properties, the mix must fulfill certain technical requirements, especially as regards mechanical strength. The more porous the material is, the more binder it in general requires in order to cohere. A high amount of ~23229~
binder for its part tends to clog the pores in the granule and to decrease its specific surface area.
Synthetic silicas are good aggregates for adsorbent with respect to their chemical and physical properties. They are well resistant to moisture, to changes in temperature and pressure, and to most substances used in adsorption applications. They have a large specific surface area, a high pore volume, and a high micro-meso-macroporosity.
However, for adsorption applications they must first be granulated. The granulating method should be one which affects the porosity of the initial material as little as possible but which at the same time gives sufficient strength to the granules so that they withstand mechanical handling.
The methods presented in the literature for the granulating of silicas are of the kinds which produce either porous but too soft ~ranules,or strong granules which are too dense for adsorption applications. The strength of porous granules can be increased by using more binder; in this case, however, the amount of micro porous adsorbent decreases and its effectiveness is reduced.
In addition to synthetic silica, a silica skeleton separated from a silicate has a pore distribution suitable for adsorption applications. However, it is necessary to use a binder in granulating it in order for the granules to obtain a mechanical strength sufficient for their further use. The literature presents different methods for the preparation of silica granules, but they have been found unsuitable for adsorption applications, mainly for the following reasons:
binders (e.g. lye, water-glass and starch) by means of which sufficiently strong granules were obtained either - significantly decreased the specific surface area of the 123229~
silica (lye, water-glass) and thereby decreased the usability of the granules for adsorption applications, or - the binder (starch) itself acted on the chemicals used for the impregnation of adsorption mixes (starch is a reducer), thereby limiting the possibilities for use of the product. The reducing action of starch can, it is true, be eliminated by thermal treatment, but then the preparation costs of the product also increase.
By using binders which did not decisively alter the porosity of the initial product (for example silica sol), sufficiently strong granules were obtained only when binder had been used at over 10 % of the weight of silica. Even then the resistance of the granules to abrasion was not sufficiently high. The costs of the binder also rose too high.
The object of the present invention is therefore to provide an economical method for the preparation of silica granules which are at the same time both very porous and have mechanical strength and withstand moisture. The object of the invention is in particular to provide a method for the preparation of silica structures suitable for adsorption mixes.
The main characteristics of the invention are given in the accompanying claims.
It has now been observed surprisingly that by using burnt lime and/or cement as the binder it is possible to obtain from a finely-ground silica-containing raw material, such as synthetic silica and a silica skeleton separated from a silicate such as phlogo~ite, very porous silica granules which are at the same time mechanically very strong and withstand moistening.
,, ~23229~
Burnt lime and/or cement is added at 2 % at minimum, preferably at approximately Lowe I, calculated from the weight of the silica-containing raw material.
It has been observed in particular that by using burnt lime as the binder it is possible to granulate from silica, for example by means of a tray granulator, porous spherical granules which withstand mechanical handling well, in such a manner that the specific surface area of the silica being granulated does not change to a noteworthy degree. When the granulation is carried out from a paste, cement can advantageously be used as a binder besides, or instead of, burnt lime. This procedure it an especially advantageous alternative when the silica is not dried but the granulation is carried out from a slurry or a filter-dry cake. Tray granulation is suitable above all for dried silica.
With respect to the strength of the granules it is important that they are allowed to prudery slowly in the presence of air, for example for 1-2 days at approximately room temperature. The result is further improved if the redrying is carried out in air which contains carbon dioxide. The final drying can be carried out at elevated temperature by keeping the granules, for example, for 1-2 hours at above lo C, preferably at Lowe C. Thereby the impregnability of the granules is maximized.
By the method according to the invention it is possible to prepare granules which are well suited for adsorption applications for example. The desired pore and strength properties have been achieved without chancing the original advantageous properties of the silica. The mechanical strength of the prepared granules is, in addition, so high that they can be used for air purification applications. In addition, the granules give off very little dust.
lZ3229S
The invention is described below in greater detail with the aid of examples.
Reference Example 1 A silica sol having a dry matter content of 15 by weight was added to 25 g dried and ground silica skeleton separated from phlogopite, in such an amount that the silica sol content of the mix, calculated as dry matter, was a) 5, b) 10, c) 15, d) 20 and e) 30 of the weight of the silica.
When necessary, water was added to the mixture in such an amount that a suitably moist paste was obtained (water approximately 60 % by weight).
my using a perforated plate, cylindrical granules (diameter 3 mm, height 4 mm) were formed from the mixes, and the granules were dried first for a few days at room temperature, then overnight at 110 C. The specific surface area of the prepared granules was determined by N2-adsorption (BET).
The resistance of the granules to compression and abrasion was checked by the hand.
Granules which contained dry matter of silica sol at most 10 % of the weight of silica fractured easily when pressed.
Their surface gave off a large amount of dust when they were chosen. When the binder amounted to more than 10 % of the weight of silica, the resistance of the granules to compression was relatively good but their resistance to abrasion continued to be poor. The BET surface area of the granules decreased when the amount of binder increased from 205 mug to 110 mug corresponding to 5 % and 30 % silica sol as dry matter of the weight of silica.
Reference Example 2 1.25 g starch was mixed with 100 g silica slurry having a solids content of 25 percent by weight. While mixing by Jo ~23Z295 means of a magnetic mixer the temperature was raised close to 100 C, at which time the mixture converted to a Mel. By means ox a perforated plate cylindrical pieces (diameter 3 mm, height 4 mm) were formed from the cooled mix. The granules were dried first at room temperature, then at 110 C. The resistance of the granules to compression and abrasion was checked by the hand. The specific surface area was determined by N2-adsorption (BET).
When pressed, the granules felt strong and, when they were shaken, they gave off very little dust. Their BET surface area was 310 mug When the granules prepared in the above manner were impregnated with a KMnO4 solution, the starch used as the binder reduced the permanganate to manganese dioxide. At this time a significant proportion of the effectiveness of the mix intended for adsorption applications was lost. The reducing action of the starch was almost completely eliminated when the granules were heat treated at 500 C.
Reference Example 3 12.5, 35.5, 72.6 and 126 ml 2-N Noah solution were added to 150 g moist silica (HO 65 % by weight). The mix was stirred well and dried to produce a moldable paste.
Cylindrical pieces (diameter 3 mm, height 4 mm) were prepared from the paste by means of a perforated plate. The pieces were dried at 110 C, and the resistance of the thus obtained granules to abrasion and compression was evaluated by the hand. Their specific surface area was determined by N2-adsorption. The results are shown in Table 1 below.
lZ32Z9~i Table l ON Wash solution BET Strength ml N go a) 12.5 205 Brittle, crumbled easily b) 35.5 110 " " "
c) 72.6 25 Relatively strong, did not give off dust d) 125 I Strong, did not give off dust A similar decrease in the surface area and a similar improvement in strength were observable when corresponding sodium additions were made in the form of water-glass. In this case, a water-glass solution was used which had a dry matter content of 25 % by weight and Sue : NATO = 2.5 (molar ratio).
Example 4 Finely-ground burnt lime at 5 % by weight was added to finely-ground silica. This mixture was fed onto a rotating granulating tray while water was sprayed onto it. The granulation conditions were adjusted in such a way that a maximum number of granules having a size of 2-5 mm was obtained. The granules were dried at room temperature in the presence of air for 1-2 days and finally at 105 C for about 2 hours.
The pore distribution of the granules thus prepared and their specific surface area were analyzed both by using a Hug porosimeter and by nitrogen adsorption. By using a Hug porosimeter the surface area obtained was 158 mug and the pore volume 1.38 ml/g, and respectively by N2-adsorption the surface area obtained was 149 m go When felt by the hand the granules were strong, and when they were screened, very little dust detached from them. The granules were ~Z3ZZ9S
impregnated with a KMnO4 solution. No changes were observed in the strength of the granules. It should be pointed out that, when granules had been prepared from both natural silicates and from synthetic silicates, by using burnt lime as the binder, the granules broke during impregnation.
Reference Example 5 Finely-ground cement was mixed at 5 %, calculated from the weight of the silica, with an aqueous slurry of a wet-ground silica skeleton of phlogopite. The tough paste thus obtained was formed into cylindrical pieces (diameter 3 mm, height 3-5 mm) by means of an extruder-type granulator. The granules were first dried in the presence of air for 2 days at room temperature and thereafter for 2 hours at 110 C.
The pore distribution and specific surface area of the granules prepared in this manner were analyzed both by means of a Hug porosimeter and by nitrogen adsorption. A surface area of 70 mug and a pore volume of 1.06 ml/g were obtained by means of a Hug porosimeter and respectively a surface area of 220 m go by nitrogen adsorption. When felt by the hand the granules were found to be even stronger than those prepared in Example 4. Their resistance to impregnation was also good. Cement-bonded silicate granules did not withstand moistening.
The pore size distributions of the granules prepared in Examples 4 and 5 are shown graphically in Figure 1.
The difference between the surface areas measured by nitrogen adsorption and a Hug porosimeter describes the micro porosity of the product. The granules prepared by the method according to the invention differ from commercial adsorbent above all with respect to Marco porosity (pore diameter over 200 no).
The MicroPro volume of commercial adsorbent (for example 123229~
XMnO4-impregnated Allah mixes presented in US. Patent 3,226,332) is only 10-30 % of the macro porosity of granules prepared by the method according to the present invention.
The pore volume of granules intended as adsorption mixes is important both for their action and for their impregnability (the higher the pore volume, the more impregnation liquid can be caused to be absorbed into the granules). Those properties of granules prepared by the methods described in the examples above which are crucial with respect to adsorption applications have been compiled into Table 2.
Table 2 Resistance to Resistance to Specific Pore Suitability compression abrasion surface volume for adsorbing M go ml/g mixes Reference example l a) poor poor 205 no b) good poor 110 no " 2 good good 310 xx)no " 3 a) poor poor 110 xxx)no b) good good I xxxx)no Example 4 good good 173 1.32 yes " 5 good good 220 1.03 "
x) binder costs too high, resistance to abrasion poor xx) reducing properties of starch are . hindrance xxx) mechanical resistance poor xxxx) surface area too small
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for the production of porous silica granules which have mechanical strength and withstand the effect of moistening, comprising: granulating a mixture of a finely-ground silica-containing raw material, water and a binder selected from the group comprising burnt lime and cement; and drying the gran-ules thus obtained, wherein the silica-containing raw material used is synthetic silica or a silica skeleton separated from a silicate.
2. A method according to claim 1, wherein the binder is added at 2% a minimum of the weight of the silica-containing raw material.
3. A method according to claim 2, wherein the binder is added at about 5-10% of the weight of the silica-containing raw material.
4. A method according to claim 1, wherein the silica granules are dried first for 1-2 days at approximately room temperature and, when necessary, in the end for 1-2 h at above 100°C.
5. A method according to claim 4, wherein the silica granules are subsequently dried at a temperature of 105-110°C.
6. A method according to claim 4, wherein the silica granules are dried in a CO2-containing air.
7. A method according to claim 1, wherein silica granules are prepared by spraying water onto a rotating tray on which there is, or onto which there is being fed, a mixture of a finely ground silica-containing raw material and burnt lime.
8. A method according to claim 1, wherein silica granules are prepared by extrusion from a paste made from a finely-ground silica-containing raw material, said binder and water.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI840827A FI69408C (en) | 1984-03-01 | 1984-03-01 | FARING REFRIGERATION FOR FUNCTIONAL RESISTANCE POROESASILIKAGRANULER MED MEKANISK HAOLLFASTHET |
| FI840827 | 1984-03-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1232295A true CA1232295A (en) | 1988-02-02 |
Family
ID=8518642
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000475469A Expired CA1232295A (en) | 1984-03-01 | 1985-02-28 | Method for the production of porous silica granules which have mechanical strength and withstand moisture |
Country Status (5)
| Country | Link |
|---|---|
| CA (1) | CA1232295A (en) |
| DE (1) | DE3504932A1 (en) |
| FI (1) | FI69408C (en) |
| GB (1) | GB2154997B (en) |
| SE (1) | SE459319B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3543530A1 (en) * | 1985-12-10 | 1987-10-15 | Saxonlord Ltd | Process for producing pellets which, inter alia, contain alkali metal oxides and/or alkaline earth metal oxides |
| DE3735245A1 (en) * | 1987-04-23 | 1989-05-03 | Hoelter Heinz | Dry gas purification to remove acidic pollutants such as SO3, SO2, HF, HCl and NOx by means of alkali-impregnated lime/aluminium cement silicates as sorbents |
| DE3717848A1 (en) * | 1987-05-27 | 1988-12-08 | Rwk Rhein Westfael Kalkwerke | Inorganic material and process for the production thereof |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB375255A (en) * | 1929-12-13 | 1932-06-23 | Ig Farbenindustrie Ag | Improvements in or relating to the granulation of powdered substances |
| GB379994A (en) * | 1932-03-07 | 1932-09-08 | Hans Frauenknecht | Method for the preparation of briquettes for introducing manganese and silicon in cupola castings |
| US3816158A (en) * | 1972-07-11 | 1974-06-11 | L Jacobs | Bonding and forming inorganic materials |
| LU68081A1 (en) * | 1973-07-24 | 1975-05-21 | ||
| AU498700B2 (en) * | 1975-06-14 | 1979-03-22 | Nippon Steel Corporation | Agglomerates for use ina blast furnace |
| DE3176577D1 (en) * | 1980-06-05 | 1988-01-28 | Ssab Division Gruvor | Agglomerates, a process for producing thereof and use thereof |
| DE3209619A1 (en) * | 1982-03-17 | 1983-09-22 | F.J. Gattys Ingenieurbüro für chem. Maschinen- und Apparatebau, 6078 Neu Isenburg | METHOD FOR PELLETIZING SUBSTANCES WITH A CRYSTALINE OR CRYSTAL-LIKE STRUCTURE |
-
1984
- 1984-03-01 FI FI840827A patent/FI69408C/en not_active IP Right Cessation
-
1985
- 1985-02-07 SE SE8500567A patent/SE459319B/en not_active IP Right Cessation
- 1985-02-13 DE DE19853504932 patent/DE3504932A1/en not_active Withdrawn
- 1985-02-28 GB GB08505149A patent/GB2154997B/en not_active Expired
- 1985-02-28 CA CA000475469A patent/CA1232295A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB2154997A (en) | 1985-09-18 |
| FI69408C (en) | 1986-02-10 |
| SE8500567D0 (en) | 1985-02-07 |
| DE3504932A1 (en) | 1985-09-05 |
| GB8505149D0 (en) | 1985-04-03 |
| SE459319B (en) | 1989-06-26 |
| FI840827A0 (en) | 1984-03-01 |
| FI840827A (en) | 1985-09-02 |
| GB2154997B (en) | 1987-10-28 |
| SE8500567L (en) | 1985-09-02 |
| FI69408B (en) | 1985-10-31 |
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| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |