CA1153507A - Disposable volatilized silica dust - Google Patents
Disposable volatilized silica dustInfo
- Publication number
- CA1153507A CA1153507A CA000379420A CA379420A CA1153507A CA 1153507 A CA1153507 A CA 1153507A CA 000379420 A CA000379420 A CA 000379420A CA 379420 A CA379420 A CA 379420A CA 1153507 A CA1153507 A CA 1153507A
- Authority
- CA
- Canada
- Prior art keywords
- silica
- granules
- volatilized
- volatilized silica
- weight
- 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
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/02—Silicon
- C01B33/021—Preparation
- C01B33/023—Preparation by reduction of silica or free silica-containing material
- C01B33/025—Preparation by reduction of silica or free silica-containing material with carbon or a solid carbonaceous material, i.e. carbo-thermal process
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B18/04—Waste materials; Refuse
- C04B18/14—Waste materials; Refuse from metallurgical processes
- C04B18/146—Silica fume
- C04B18/147—Conditioning
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
- C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
- C09C1/28—Compounds of silicon
- C09C1/30—Silicic acid
- C09C1/3009—Physical treatment, e.g. grinding; treatment with ultrasonic vibrations
- C09C1/3036—Agglomeration, granulation, pelleting
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/50—Agglomerated particles
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/10—Solid density
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/80—Compositional purity
- C01P2006/82—Compositional purity water content
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Inorganic Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Civil Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Silicon Compounds (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
A B S T R A C T
There is provided a process for the preparation of substantially water-insoluble granules of volatilized silica by first mixing a predetermined amount of volatil-ized silica with 40 to 60% by weight of water and from 1 to 3% by weight of an alkaline earth metal oxide and when a thick slurry is obtained, adding thereto from 10 to 50% of the initial amount of volatilized silica and continuing the mixing until hard granules are obtained.
These granules are suitable for disposal in open pits or dumps.
silica with 40 to 60% by weight of water and from 1 to 3% by weight of an alkaline earth metal oxide and when a thick slurry is obtained, adding thereto from 10 to 50% of the initial amount of volatilized silica and continuing the mixing until hard granules are obtained.
These granules are suitable for disposal in open pits or dumps.
There is provided a process for the preparation of substantially water-insoluble granules of volatilized silica by first mixing a predetermined amount of volatil-ized silica with 40 to 60% by weight of water and from 1 to 3% by weight of an alkaline earth metal oxide and when a thick slurry is obtained, adding thereto from 10 to 50% of the initial amount of volatilized silica and continuing the mixing until hard granules are obtained.
These granules are suitable for disposal in open pits or dumps.
silica with 40 to 60% by weight of water and from 1 to 3% by weight of an alkaline earth metal oxide and when a thick slurry is obtained, adding thereto from 10 to 50% of the initial amount of volatilized silica and continuing the mixing until hard granules are obtained.
These granules are suitable for disposal in open pits or dumps.
Description
l~S3S~7 The present invention relates to the disposal of silica fume or volatilized silica by agglomerating it in the form of a coarse hard granules suitable for disposal in open pits or dumps.
BACKGROUND OF THE INVENTION
Silicon and ferrosilicon are obtained by sub-jecting quartz, when silicon is desired, or quartz and an iron bearing material, when ferrosilicon is desired, to a reduction with coke or coal and woodchips in an open electric arc furnace. The quartz and coke or coal used must be as pure as possible in order to obtain the purest silicon or ferrosilicon possible.
Quartz is one of the crystalline form of silicon dioxide and its reduction with carbon does not follow the reaction:
si2 + C si + CO2 In fact, there is an intermediate reaction which takes place wherein a suboxide of silicon is formed according to the reaction:
SiO2 + C---~SiO + CO
Part of the gaseous suboxide of silicon which is formed escapes with the CO gas and will then react with the oxygen in the air in accordance with the reaction:
sio + ~ o >sio B
115235~7 The gases which escape from the furnace will contain minor amounts of other metallic gases which are mainly very volatile. Alkali metals, such as potassium and sodium, condense at the same time as the suboxide of silicon to form glassy microscopic particles. These glassy microscopic particles are known as silica fumes, volatilized silica or submicron silica. These particles are collected through various filtering systems. The amount of silica fumes or volatilized silica represents about 250 to 500 kilograms per ton of metal produced.
The expression 'volatilized silica', whenever used herein, is intended to cover the very fine silica parti-cles which are usually referred to either as volatilized silica, silica fumes or silica dust and also volatilized ferrosilicon, ferrosilicon fumes or ferrosilicon dust.
Further, volatilized silica is characterized by having a very fine particle size. The average diameter of the glassy microscopic particles varies from 0.5 to 1.0 ~m, this diameter being from 50 to 100 times smaller than that of Portland cement or fly ash. Also, because of its microscopic size, the specific surface of volatil-ized silica can be as high as 20 000 m2/kg, which is at least 50 times greater than that of Portland cement or fly ash.
The chemical composition of volatilized silica will vary slightly whether it is obtained from the manu-facture of silicon or ferrosilicon, and generally the l~S35~)7 silicon dioxide content will vary from 85 to 95~, the carbon content will be from 0.2 to 5.0% while the content of aluminum oxide ana calcium oxide will generally be less than 2%.
Furthermore, the chemical composition of vola-tilized silica is quite different than that of pozzolan and fly ash. The volatilized silica has a SiO2 content much higher than that of pozzolan and fly ash while the aluminum oxide content of the latter two compounds is substantially greater than that of the volatilized silica dust.
The disposal of such large volumes of volatil-ized silica represents a problem because of the physico-chemical properties of volatilized silica. Volatilized silica is very light in weight since its bulk density is from 200 to 250 kg/m3, which means that 1 kg of volatil-ized silica occupies a volume which is 4 to 5 times greater than 1 kg of Portland cement or fly ash.
It will be appreciated that the disposal of large quantities of volatilized silica causes an environ-mental problem. Accordingly, for most producers of silicon or ferrosilicon, the large volumes of the vola-tilized silica produced creates a disposal problem and so far most companies are conte~t to bury the volatilized silica by-product. Nevertheless, this is not an answer to the problem because now environmentalists are taking note of this type of disposal and in certain countries 1~5~3S~7 recent legislation has been set up to control or prevent this type of disposal.
It is known that a small amount of volatilized silica could be used in certain countries to replace a small amount of Portland cement in the manufacture of concrete. In this case generally the volatilized silica is sold in the form of a dilute slurry. This operation can be done when the silicon manufacturing plant is within a short distance of the concrete mixing plant and where the climatic condition of the country is such tha~
transporting an aqueous slurry of volatilized silica will not cause any problem in the winter months.
Since as the concrete industry is a seasonal one with peak demands in the summer and low demands in the winter, from time to time the silicon producer can be faced with the undesirable situation of having silica fumes which cannot be disposed of to the cement industry.
In fact, the electric arc furnaces operate 24 hours a day and 365 days a year, so that with the constant production of silica fumes there is no other solution than to dis-pose of this excess silica fumes in a dump.
One manner of disposing of volatilized silica has been to form an aqueous slurry of the volatilized silica and to bury same in open pits. Another manner of disposing has been to transport the dry silica fumes to an artificial pond and let it deposit at the bottom of the pond. Finally silica fumes can also be disposed 1~5350~
~ 5 --after its pelletization with Portland cement in a disc pelletizer or drum granulator to produce insoluble pellets. The first and the second disposal procedures are unacceptable solutions to an environmental problem while the last procedure is very difficult to operate and involves an extra expense.
Accordingly it would be highly desirable if a procedure for dispos~ng of volatilized silica in a safe and unexpensive manner could be devised.
SIJ ~RY OF THE INVENTION
In accordance with the present invention, there is now provided a process for agglomerating volatilized silica whereby the granules obtained are substantially water-insoluble and can readily be disposed of in an open pit or dump without causing an environmental problem.
Essentially, the novel process of the present invention comprises mixing a predetermined amount of volatilized silica with from about 40 to 60~ by weight of water with from 1 to 3~ of an alkaline earth metal oxide and, when the mixture has the consistency of a thick slurry, incorporating therein from about 10 to 50% of the initial amount of volatilized silica, mixing the whole and recovering coarse hard granules having a diameter of from about 5 to about 40 mm.
DETAILED DESCRIPTION OF T~E INVENTION
The problem of disposing of volatilized silica has been solved by providing granules which are sub-1~535~7 stantially water-insoluble and possess a relatively high resistance to disintegration. It i5 known that a paste of volatilized silica is suddenly obtained when up to 38 + 2% of water is added to the volatilized silica. If more water is added, the paste is transformed to a slurry, the fluidity of which increases with continued addition of water.
In accordance with the present invention, there is provided a novel process granulating volatilized silica. Essentially the process comprises preparing a slurry by mixing a predetermined amount of volatilized silica with 1 to 3~ by weight of an alkaline earth metal hydroxide, preferably, calcium oxide, and 40 to 60% by weight of water, and then mixing the thus obtained slurry with a further quantity of volatilized silica correspond-ing to 10 to 50% of the initial amount of volatilized silica used in the preparation of the aqueous slurry until granules are obtained.
The granules which are obtained by the novel 2a process of the present invention will vary in size depending on the mixing speed u~ed in the second mixing step. It has been found that when the second mixing step is carried out at high speeds varying from about 1000 to 1400 rpm coarse granules having a diameter of from about 5 to about 10 mm are obtained. On the other hand, when the second mixing step is carried out at low speeds under 500 rpm, granules having a diameter of from about 10 to llS3S~7 40 mm are obtained. Both types of granules have a water content of about 35 to 38~ by weight. The bulk density of these granules is from 600 to 790 kg/m3.
It will be re~dily observed that the procedures of the present invention provides unexpected advantages.
One important advantage is the densification factor which is 3 to 3.5 times the initial volatilized silica. In other words, one cubic metre of volatilized silica gran-ules weight 3 to 3.5 times more than one cubic metre of untreated volatilized silica. The consequence of this feature is that transportation costs will be reduced 3 to 3.5 times and the space required to bury an equivalent volume of volatilized silica will be reduced accordingly.
Also, trucks with an open box covered with a canvas can be used instead of the expensive air tight box truck for the transportation to a disposal site.
Another advantage of the process of the present invention, is its relative simplicity in operation and in the equipment needed. All that is required is a mixer with a mixing blade, the speed of which has been adjusted within the range previously mentioned. The size of the mixer is selected in accordance with volume of volatil-ized silica to be treated.
Finally, a further advantage is in the volatil-ized silica granules of the present invention. These granules are for all practical purpose resistant to disintegration or erosion by water and thus they can ~153S~7 safely be dumped in an open pit.
The present invention will be more readily understood by referring to the following examples which are given to illustrate the invention only.
15 kg of volatilized silica are mixed at high speed for one minute with 450 g of hydrated lime and 8.0 liters of water and there is obtained a black thick slurry having a water content of 52%. There is then added to this slurry 6 kg of dry volatilized silica and ! mixing is continued at a high speed of 1360 rpm for 2 minutes. Small hard granules having a particle size of from 5 to 10 mm and having a water content of 37% are obtained.
15 kg of volatilized silica are mixed at high speed for one minute with 150 g of hydrated lime and 8.0 liters of water and there is obtained a thick black slurry. There is then added to the slurry 6 kg of dry volatilized silica and mixing is continued at a slow speed of 50 rpm for 2 minutes. Larger granules having a particle size of from 10 to 40 mm and a water content of 37% are obtained.
BACKGROUND OF THE INVENTION
Silicon and ferrosilicon are obtained by sub-jecting quartz, when silicon is desired, or quartz and an iron bearing material, when ferrosilicon is desired, to a reduction with coke or coal and woodchips in an open electric arc furnace. The quartz and coke or coal used must be as pure as possible in order to obtain the purest silicon or ferrosilicon possible.
Quartz is one of the crystalline form of silicon dioxide and its reduction with carbon does not follow the reaction:
si2 + C si + CO2 In fact, there is an intermediate reaction which takes place wherein a suboxide of silicon is formed according to the reaction:
SiO2 + C---~SiO + CO
Part of the gaseous suboxide of silicon which is formed escapes with the CO gas and will then react with the oxygen in the air in accordance with the reaction:
sio + ~ o >sio B
115235~7 The gases which escape from the furnace will contain minor amounts of other metallic gases which are mainly very volatile. Alkali metals, such as potassium and sodium, condense at the same time as the suboxide of silicon to form glassy microscopic particles. These glassy microscopic particles are known as silica fumes, volatilized silica or submicron silica. These particles are collected through various filtering systems. The amount of silica fumes or volatilized silica represents about 250 to 500 kilograms per ton of metal produced.
The expression 'volatilized silica', whenever used herein, is intended to cover the very fine silica parti-cles which are usually referred to either as volatilized silica, silica fumes or silica dust and also volatilized ferrosilicon, ferrosilicon fumes or ferrosilicon dust.
Further, volatilized silica is characterized by having a very fine particle size. The average diameter of the glassy microscopic particles varies from 0.5 to 1.0 ~m, this diameter being from 50 to 100 times smaller than that of Portland cement or fly ash. Also, because of its microscopic size, the specific surface of volatil-ized silica can be as high as 20 000 m2/kg, which is at least 50 times greater than that of Portland cement or fly ash.
The chemical composition of volatilized silica will vary slightly whether it is obtained from the manu-facture of silicon or ferrosilicon, and generally the l~S35~)7 silicon dioxide content will vary from 85 to 95~, the carbon content will be from 0.2 to 5.0% while the content of aluminum oxide ana calcium oxide will generally be less than 2%.
Furthermore, the chemical composition of vola-tilized silica is quite different than that of pozzolan and fly ash. The volatilized silica has a SiO2 content much higher than that of pozzolan and fly ash while the aluminum oxide content of the latter two compounds is substantially greater than that of the volatilized silica dust.
The disposal of such large volumes of volatil-ized silica represents a problem because of the physico-chemical properties of volatilized silica. Volatilized silica is very light in weight since its bulk density is from 200 to 250 kg/m3, which means that 1 kg of volatil-ized silica occupies a volume which is 4 to 5 times greater than 1 kg of Portland cement or fly ash.
It will be appreciated that the disposal of large quantities of volatilized silica causes an environ-mental problem. Accordingly, for most producers of silicon or ferrosilicon, the large volumes of the vola-tilized silica produced creates a disposal problem and so far most companies are conte~t to bury the volatilized silica by-product. Nevertheless, this is not an answer to the problem because now environmentalists are taking note of this type of disposal and in certain countries 1~5~3S~7 recent legislation has been set up to control or prevent this type of disposal.
It is known that a small amount of volatilized silica could be used in certain countries to replace a small amount of Portland cement in the manufacture of concrete. In this case generally the volatilized silica is sold in the form of a dilute slurry. This operation can be done when the silicon manufacturing plant is within a short distance of the concrete mixing plant and where the climatic condition of the country is such tha~
transporting an aqueous slurry of volatilized silica will not cause any problem in the winter months.
Since as the concrete industry is a seasonal one with peak demands in the summer and low demands in the winter, from time to time the silicon producer can be faced with the undesirable situation of having silica fumes which cannot be disposed of to the cement industry.
In fact, the electric arc furnaces operate 24 hours a day and 365 days a year, so that with the constant production of silica fumes there is no other solution than to dis-pose of this excess silica fumes in a dump.
One manner of disposing of volatilized silica has been to form an aqueous slurry of the volatilized silica and to bury same in open pits. Another manner of disposing has been to transport the dry silica fumes to an artificial pond and let it deposit at the bottom of the pond. Finally silica fumes can also be disposed 1~5350~
~ 5 --after its pelletization with Portland cement in a disc pelletizer or drum granulator to produce insoluble pellets. The first and the second disposal procedures are unacceptable solutions to an environmental problem while the last procedure is very difficult to operate and involves an extra expense.
Accordingly it would be highly desirable if a procedure for dispos~ng of volatilized silica in a safe and unexpensive manner could be devised.
SIJ ~RY OF THE INVENTION
In accordance with the present invention, there is now provided a process for agglomerating volatilized silica whereby the granules obtained are substantially water-insoluble and can readily be disposed of in an open pit or dump without causing an environmental problem.
Essentially, the novel process of the present invention comprises mixing a predetermined amount of volatilized silica with from about 40 to 60~ by weight of water with from 1 to 3~ of an alkaline earth metal oxide and, when the mixture has the consistency of a thick slurry, incorporating therein from about 10 to 50% of the initial amount of volatilized silica, mixing the whole and recovering coarse hard granules having a diameter of from about 5 to about 40 mm.
DETAILED DESCRIPTION OF T~E INVENTION
The problem of disposing of volatilized silica has been solved by providing granules which are sub-1~535~7 stantially water-insoluble and possess a relatively high resistance to disintegration. It i5 known that a paste of volatilized silica is suddenly obtained when up to 38 + 2% of water is added to the volatilized silica. If more water is added, the paste is transformed to a slurry, the fluidity of which increases with continued addition of water.
In accordance with the present invention, there is provided a novel process granulating volatilized silica. Essentially the process comprises preparing a slurry by mixing a predetermined amount of volatilized silica with 1 to 3~ by weight of an alkaline earth metal hydroxide, preferably, calcium oxide, and 40 to 60% by weight of water, and then mixing the thus obtained slurry with a further quantity of volatilized silica correspond-ing to 10 to 50% of the initial amount of volatilized silica used in the preparation of the aqueous slurry until granules are obtained.
The granules which are obtained by the novel 2a process of the present invention will vary in size depending on the mixing speed u~ed in the second mixing step. It has been found that when the second mixing step is carried out at high speeds varying from about 1000 to 1400 rpm coarse granules having a diameter of from about 5 to about 10 mm are obtained. On the other hand, when the second mixing step is carried out at low speeds under 500 rpm, granules having a diameter of from about 10 to llS3S~7 40 mm are obtained. Both types of granules have a water content of about 35 to 38~ by weight. The bulk density of these granules is from 600 to 790 kg/m3.
It will be re~dily observed that the procedures of the present invention provides unexpected advantages.
One important advantage is the densification factor which is 3 to 3.5 times the initial volatilized silica. In other words, one cubic metre of volatilized silica gran-ules weight 3 to 3.5 times more than one cubic metre of untreated volatilized silica. The consequence of this feature is that transportation costs will be reduced 3 to 3.5 times and the space required to bury an equivalent volume of volatilized silica will be reduced accordingly.
Also, trucks with an open box covered with a canvas can be used instead of the expensive air tight box truck for the transportation to a disposal site.
Another advantage of the process of the present invention, is its relative simplicity in operation and in the equipment needed. All that is required is a mixer with a mixing blade, the speed of which has been adjusted within the range previously mentioned. The size of the mixer is selected in accordance with volume of volatil-ized silica to be treated.
Finally, a further advantage is in the volatil-ized silica granules of the present invention. These granules are for all practical purpose resistant to disintegration or erosion by water and thus they can ~153S~7 safely be dumped in an open pit.
The present invention will be more readily understood by referring to the following examples which are given to illustrate the invention only.
15 kg of volatilized silica are mixed at high speed for one minute with 450 g of hydrated lime and 8.0 liters of water and there is obtained a black thick slurry having a water content of 52%. There is then added to this slurry 6 kg of dry volatilized silica and ! mixing is continued at a high speed of 1360 rpm for 2 minutes. Small hard granules having a particle size of from 5 to 10 mm and having a water content of 37% are obtained.
15 kg of volatilized silica are mixed at high speed for one minute with 150 g of hydrated lime and 8.0 liters of water and there is obtained a thick black slurry. There is then added to the slurry 6 kg of dry volatilized silica and mixing is continued at a slow speed of 50 rpm for 2 minutes. Larger granules having a particle size of from 10 to 40 mm and a water content of 37% are obtained.
Claims (5)
1. A process for preparing substantially water-insoluble granules of volatilized silica which comprises mixing a predetermined amount of volatilized silica with about 40 to about 60% by weight of water and from 1 to 3% by weight of an alkaline earth metal oxide solution until a thick slurry is obtained, then adding to said slurry an amount of from 10 to 50% of the initial amount of volatilized silica used in the prepa-ration of the aqueous slurry while continuing the mixing until coarse hard granules having a diameter of from about 5 to about 40 mm are obtained.
2. The process of Claim 1, wherein the second mixing step is carried out at a speed of from about 1000 to about 1400 rpm and the coarse granules obtained have a diameter of from about 5 to about 10 mm.
3. The process of Claim 1, wherein the second mixing step is carried out at a speed of from about 500 to about 800 rpm and the coarse granules obtained have a diameter of from 10 to about 40 mm.
4. The process of Claim 2, wherein the alka-line earth metal oxide is calcium oxide.
5. The process of Claim 3, wherein the alka-line earth metal oxide is calcium oxide.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000379420A CA1153507A (en) | 1981-06-10 | 1981-06-10 | Disposable volatilized silica dust |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000379420A CA1153507A (en) | 1981-06-10 | 1981-06-10 | Disposable volatilized silica dust |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1153507A true CA1153507A (en) | 1983-09-13 |
Family
ID=4120193
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000379420A Expired CA1153507A (en) | 1981-06-10 | 1981-06-10 | Disposable volatilized silica dust |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1153507A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0692524A1 (en) * | 1994-07-11 | 1996-01-17 | Heraeus Quarzglas GmbH | Process for preparing silica granules and their use |
-
1981
- 1981-06-10 CA CA000379420A patent/CA1153507A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0692524A1 (en) * | 1994-07-11 | 1996-01-17 | Heraeus Quarzglas GmbH | Process for preparing silica granules and their use |
| DE4424044A1 (en) * | 1994-07-11 | 1996-01-18 | Heraeus Quarzglas | Process for the preparation of silica granules and use of the granules thus produced |
| US5643347A (en) * | 1994-07-11 | 1997-07-01 | Heraeus Quarzglas Gmbh | Process for manufacture of silica granules |
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