GB2078703A - Producing active silica - Google Patents
Producing active silica Download PDFInfo
- Publication number
- GB2078703A GB2078703A GB8119975A GB8119975A GB2078703A GB 2078703 A GB2078703 A GB 2078703A GB 8119975 A GB8119975 A GB 8119975A GB 8119975 A GB8119975 A GB 8119975A GB 2078703 A GB2078703 A GB 2078703A
- Authority
- GB
- United Kingdom
- Prior art keywords
- active silica
- drying
- over
- wet
- micrometres
- 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.)
- Granted
Links
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims abstract description 45
- 239000000377 silicon dioxide Substances 0.000 title claims abstract description 22
- 238000000926 separation method Methods 0.000 claims abstract description 16
- 238000000605 extraction Methods 0.000 claims abstract description 15
- 238000012545 processing Methods 0.000 claims abstract description 14
- 238000001035 drying Methods 0.000 claims abstract description 13
- 239000002253 acid Substances 0.000 claims abstract description 10
- 238000010981 drying operation Methods 0.000 claims abstract description 10
- 238000000227 grinding Methods 0.000 claims abstract description 8
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 7
- 238000009825 accumulation Methods 0.000 claims abstract description 6
- 229910052681 coesite Inorganic materials 0.000 claims abstract description 6
- 229910052906 cristobalite Inorganic materials 0.000 claims abstract description 6
- 150000004760 silicates Chemical class 0.000 claims abstract description 6
- 229910052682 stishovite Inorganic materials 0.000 claims abstract description 6
- 229910052905 tridymite Inorganic materials 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 39
- 239000000463 material Substances 0.000 claims description 29
- 238000005406 washing Methods 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 5
- 239000008187 granular material Substances 0.000 claims description 2
- 230000000717 retained effect Effects 0.000 claims description 2
- 239000007921 spray Substances 0.000 claims description 2
- 238000001694 spray drying Methods 0.000 claims description 2
- 230000014759 maintenance of location Effects 0.000 claims 2
- 239000002245 particle Substances 0.000 claims 2
- 239000011164 primary particle Substances 0.000 claims 1
- 238000001238 wet grinding Methods 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- 238000002386 leaching Methods 0.000 description 4
- 238000001816 cooling Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000009837 dry grinding Methods 0.000 description 2
- 239000000391 magnesium silicate Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000010450 olivine Substances 0.000 description 2
- 229910052609 olivine Inorganic materials 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 1
- 238000006124 Pilkington process Methods 0.000 description 1
- WYTGDNHDOZPMIW-RCBQFDQVSA-N alstonine Natural products C1=CC2=C3C=CC=CC3=NC2=C2N1C[C@H]1[C@H](C)OC=C(C(=O)OC)[C@H]1C2 WYTGDNHDOZPMIW-RCBQFDQVSA-N 0.000 description 1
- 150000001805 chlorine compounds Chemical class 0.000 description 1
- 229910001919 chlorite Inorganic materials 0.000 description 1
- 229910052619 chlorite group Inorganic materials 0.000 description 1
- QBWCMBCROVPCKQ-UHFFFAOYSA-N chlorous acid Chemical compound OCl=O QBWCMBCROVPCKQ-UHFFFAOYSA-N 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- DKAGJZJALZXOOV-UHFFFAOYSA-N hydrate;hydrochloride Chemical compound O.Cl DKAGJZJALZXOOV-UHFFFAOYSA-N 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 description 1
- 235000019792 magnesium silicate Nutrition 0.000 description 1
- 229910052919 magnesium silicate Inorganic materials 0.000 description 1
- 235000012243 magnesium silicates Nutrition 0.000 description 1
- 238000007885 magnetic separation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910001510 metal chloride Inorganic materials 0.000 description 1
- 239000010445 mica Substances 0.000 description 1
- 229910052618 mica group Inorganic materials 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- 235000012222 talc Nutrition 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
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
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/124—Preparation of adsorbing porous silica not in gel form and not finely divided, i.e. silicon skeletons, by acidic treatment of siliceous materials
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Dispersion Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
Abstract
Active silica in an improved state of purity and with an improved degree of whiteness, and with a large internal surface area, in particular an active silica having a BET number of more than 200 g/m<2>, a degree of whiteness of over 80 and an SiO2 content of over 83 to 85%, is produced from natural silicates with a grain size of preferably 0 to 1 mm, by acid extraction, wet separation, preferably shaker table processing, dewatering, gentle drying. that is to say, a drying operation which is performed in such a manner as to avoid an accumulation of heat, and grinding.
Description
SPECIFICATION
Method of producing active silica
The method according to the present invention is concerned with the production of active silica from natural silicates, by separating off undesired constituents from natural acid-extractible silicates, dewatering the acid-extracted silicates, and gently drying to adjust and achieve desired specific surface and degree of whiteness of the active silica product.
Active silica can be produced by hydrochloric acid extraction from natural alkaline earth silicates, preferably magnesium silicates (ultra-basic rocks such as serpentine and olivine), see Austrian patent specification No 352 684; in that Austrian patent specification, in accordance with the material requirements known at that time, the aim set is limited to achieving a high internal surface area.
However, from the point of view of purity and whiteness, the materials produced in accordance with the known methods no longer correspond to the present-day technical requirements set in various fields of use.
The present invention provides a method of producing active silica which comprises acid extraction of natural silicate, wet separation of the acid-treated material, and dewatering of the separated material followed by drying so as to avoid the accumulation of heat and grinding.
In preferred embodiments of the invention the basic starting material is a silicate with a grain size of preferably 0 to 1 my, in particular 0.02 to 0.75 mm, leaching (extraction) of which is effected with azeotropic hydrochloric acid-water mixture in a single stage, batchwise or continuous manner, in a cocurrent or counter current mode, down to residual MgO contents of below 4%, preferably below 3%, and a residual HCI value in respect of the lye of below 2%, preferably below 0.2%. The lye employed contains small amounts of colloidally dissolved silica, besides the dissolved chlorides. In order to avoid resorption phenomena, separation of the solution residue and the subsequent washing and drying thereof in accordance with the method of the invention, is now performed.The method according to the invention provides that the acid-extracted material is subjected to a separating process by a wet separating process, preferably shaker table processing, and that the material is dewatered and subjected to a gentle drying operation, that is to say, a drying operation which is performed in such a way as to avoid an accumulation of heat, and ground.
Separation of the solution residue from the lye is preferably effected hot and quickly, directly after the leaching operation, without previous cooling down. It is performed for example by means of a dewatering screen with mesh widths of about 30 to 100 ym, but it may also be effected by means of bowl classifiers or hydrocyclones, such as for example hydroseparators.
The washing operation is preferably effected in a multi-stage manner in counter-current with tap water, to a value of 0.1% residual chloride (HCI and metal chlorides).
A shaker table processing operation is carried out for the purposes of separating off accompanying materials. In principle, other methods such as magnetic separation and/or sink-float processes are also possible, but the use of shaker table processing has proved to be the most advantageous, for the purposes of achieving the desired material parameters. The following are passed to the separation operation:
1. Insoluble components originating from the acid extraction step,
2. Components which are difficult to dissolve, such as olivine,
3. Insoluble components possibly originating from the stirrer shadows in the extraction step,
4. Chromites, mica and quartz components, and
5. Silicatically combined, non-extractible residual minerals, for example talcum and chlorite.
In order to achieve the maximum possible surface areas, the dewatering operation should preferably be effected quickly directly after the shaker table processing operation, and is desirably effected, as in the case of the separation operation, by a dewatering screen, hydrocyclone or hydroseparators or suitable filter presses.
The gentle drying step is of decisive importance for achieving high specific surface areas of the material which is purified and prepared in accordance with the preceding process steps. It may be effected using various pieces of equipment such as belt, flowing bed, drum, spray, vacuum or flow driers. Essential factors are avoiding a build-up or accumulation of heat and that a condition of equilibrium as between the supply of heat and the removal of vapour is at least approximately maintained. When the water escapes, there should not be a pressure difference. If care is taken to provide a sufficient removal of heat, the drying operation, for example spray drying, may also be effected rapidly. In particular, overheating of the surface of the material is to be avoided, while the residual moisture content is still high.This careful reduction in moisture content to O to 1%, preferably 0.03 to 0t5% residual moisture, in unground material, is preferably continued until about 2/3 and in particular 4/5 of the moisture has escaped, with respect to the initial condition. The drying operation is only intended to concern moisture, whereas the chemically bound water is to be retained. For this purpose, the operation should not exceed 1 500C surface temperature of the material or 3000C drying gas temperature, for example hot air.
The drying grinding operation may be performed as a subsequent method step, with ball, pebble or vibrating or jet mills. The desired residual moisture content for the dry grinding operation is below 1%, preferably below 0.5%. The sample which is ground up for example to about 30 um gives two defined products, in a subsequent sifting operation with a separation limit at about 10 ym: 1) 0--10 ,um: pigment products
2) 10-30 ,um: other fields of use.
However, it is also possible, when using the last-mentioned grinding apparatus, the jet mill, to produce virtually 100% 0-10 ym fine material, although with a higher level of power consumption.
For some areas of use, it is preferred to have material produced by a wet grinding operation. The
method remains the same, up to and including the shaker table processing operation, in the method steps described hereinbefore. For example, the wet grinding operation which follows the shaker table
processing operation is performed using a stirrer ball miil, in which respect the "Attritor" (discontinuous
stirrer ball mill) has been found to be the most suitable piece of equipment. If desired, a hydrocyclone
can also be connected downstream thereof.
The wet grinding operation starts with a grain size of 30 to 300 micrometres, and is set to a final limit grain size of 10 0 micrometres, with the predominant proportion being below 5 micrometres. A material which is spray-dried after the wet grinding operation is produced in the form of a fine granulate with a moisture content of below 20% and preferably below 5%, which is soluble as such or which can also be made readily soluble by the addition of small amounts of dispersing agents.
The invention is described in greater detail hereinafter with reference to a diagram of the method
and an Example:
Diagram of the method Grain supply l Hot extraction (leaching) Separation (solution residue from the lye) Washing (of the solution residue) Processing (of the solution residue by separation of the accompanying substances) Dewatering Variation (a) / \ Variation (b) Variation (a) 'JVet grinding Drying Wet grinding Dry grinding Drying (sifting, \ / \ Storage / Dispatch, transportation EXAMPLE
The magnesium silicate which is introduced into a stirring vessel for the hot extraction operation, with a grain size of 0 to 0.75 mm, is of the following chemical analysis:
Loss on ignition 12.5%
SiO2 38.0% Al203 + TiO2 1.0%
Fe203 7.0%
CaO 0.7%
MgO 40.0%
K2O 0.1%
Na2O 0.2% SO
3 0.5%
100.0% The extraction operation (leaching) was carried out with an azeotropic HCI-H2O-mixture (about 20% hydrochloric acid), with stirring for 2 hours, at a temperature of 80cm, whereupon the solution residue had a BET specific surface area of 220 m2/g.
Then, after brief cooling, separation of the solution residue from the lye was offected. After washing free of acid and direct processing of the solution residue on the shaker table, the material was dewatered and in accordance with:
Variation (a): gently dried at a maximum surface temperature of 1 500C, ground and sifted or, in accordance with:
Variation (b): wet-ground and only subsequently gently dried as in (a).
Both materials had a 90% finess of below 10 ym and had the following test values:
Loss on ignition 8.30%
SiO2 84.05% Al203 + TiO2 1.63%
Fe203 0.36%
MgO 4.37% 99.27% Specific surface area (BET) 231.4 m2/g
Degree of whiteness 81.7%
A material from the same extraction operation, in regard to which the operations of separation,
washing and processing were not carried out immediately and which was sharply dried after dewatering
at surface temperatures of between 200 and 3000C, had, in comparison thereto, only surface area
values of between 60 and 80 m2/g.
A material which was not subjected to the shaker table processing had, from the same extraction,
and in comparison thereto, only a degree of whiteness of 70 to 75%.
The method according to the invention can yield active silica having a BET surface area of over
200 m2/g, a degree of whiteness of over 80, and an SiO2 content of over 83 wt.% -- e.g. over 85 wt.%.
Claims (20)
1. A method of producing active silica which comprises acid extraction of natural silicate, wet
separation of the acid-treated material, and dewatering of the separated material followed by drying so
as to avoid the accumulation of heat and grinding.
2. A method according to claim 1 wherein the natural silicate is of a grain size of up to 1 mm.
3. A method according to claim 2 wherein the natural silicate is of a grain size of from 0.02 to 0.75 mm.
4. A method according to any of claims 1 to 3 wherein the wet separation comprises shaker table processing.
5. A method according to any of claims 1 to 4 wherein the acid-treated material is separated from the treatment solution directly after the acid extraction and washed prior to the wet separation.
6. A method according to claim 5 wherin the washing is a multi-stage countercurrent washing with water.
7. A method according to any of claims 1 to 6 wherein the drying is conducted to remove at least 2/3 of the free moisture with retention of chemically bound water.
8. A method according to claim 7 wherein the drying is conducted to remove about 4/5 of the free moisture with retention of chemically bound water.
9. A method according to any of claims 1 to 8 wherein the dewatered material is dried and then dry ground.
1 0. A method according to claim 9 wherein the dried material is ground and separated to give a fraction of up to 10 micrometres particle size and a fraction of 10 to 30 micrometres particle size.
11. A method according to any of claims 1 to 8 wherein the dewatered material is wet ground and then dried.
1 2. A method according to claim 11 wherein the wet ground material is spray dried.
13. A method of producing active silica, the method being substantially as hereinbefore described in the Example.
14. Active silica obtained by a method according to any of claims 1 to 13.
15. Active silica according to claim 14 having a BET surface area of over 200 m2/g, a degree of whiteness of over 80, and an SiO2 content of over 83%.
1 6. A method of producing active silica in an improved state of purity and with an improved degree of whiteness, and with a large internal surface area, in particular an active silica having a BET number of more than 200 g/m2, a degree of whiteness of over 80 and an SiO2 content of over 83 to 85%, from natural silicates with a grain size of preferably 0 to 1 and in particular 0.02 to 0.75, by acid extraction, separation, drying and grinding, characterised in that the acid-extracted material is subjected to a separating process by a wet separating process, preferably shaker table processing, and that the material is dewatered and subjected to a gentle drying operation, that is to say, a drying operation which is performed in such a manner as to avoid an accumulation of heat, and ground.
1 7. A method according to claim 1 6 characterised in that the separating process is performed by the solution residue being separated directly after the extraction step and washed preferably in a multistage mode in counter-current with water, whereafter the shaker table processing and dewatering operations are effected, wherein dewatering and separation of the solution residue is effected for example by means of dewatering screens or hydroseparators.
1 8. A method according to claim 16 or claim 1 7 characterised in that the gentle drying operation is carried out in such a way that 2/3 and preferably 4/5 of the moisture is removed, while the chemically bound water is retained.
1 9. A method according to one of claims 16 to 18 characterised in that after the gentle drying operation has been performed, the material is brought to the required degree of fineness of O to 10 micrometres and 10 to 30 micrometres respectively by circulatory grinding (mill and air sifter).
20. A method according to one of claims 1 6 to 1 9 characterised in that the gentle drying operation is performed by means of spray drying, forming a water-soluble fine granulate of less than 0.05 mm with a moisture content below 20%, preferably below 5%, with a primary particle size of below 10 micrometres.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT0338780A AT377958B (en) | 1980-06-27 | 1980-06-27 | METHOD FOR PRODUCING ACTIVE SILICA |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2078703A true GB2078703A (en) | 1982-01-13 |
| GB2078703B GB2078703B (en) | 1983-06-08 |
Family
ID=3549757
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8119975A Expired GB2078703B (en) | 1980-06-27 | 1981-06-29 | Producing active silica |
Country Status (4)
| Country | Link |
|---|---|
| AT (1) | AT377958B (en) |
| DE (1) | DE3121920C2 (en) |
| GB (1) | GB2078703B (en) |
| NO (1) | NO160200C (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5302364A (en) * | 1991-12-25 | 1994-04-12 | R & D Silicate Products, Ltd. | Process for the preparation of amorphous silica |
| WO1995007235A1 (en) * | 1993-09-06 | 1995-03-16 | Svein Olerud | A method for manufacturing spherical silica from olivine |
| WO2005068363A1 (en) | 2004-01-14 | 2005-07-28 | Cod Technologies A.S. | Process for production of precipitated silica from olivine |
| EP1598114A1 (en) * | 2004-05-18 | 2005-11-23 | Outreau Technologies | Method of separating silica and olivine from a mixture containing these substances and device for carrying out said method |
| WO2007054955A1 (en) * | 2005-11-10 | 2007-05-18 | Council Of Scientific & Industrial Research | A process for the preparation of sodium silicate from kimberlite tailings |
| US8110166B2 (en) | 2002-11-27 | 2012-02-07 | Silmag Da | Process for producing silica from olivine |
| WO2016176772A1 (en) | 2015-05-06 | 2016-11-10 | Alliance Magnésium | Method for the production of amorphous silica with controlled specific surface area from magnesium silicate ore |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109371597A (en) * | 2018-11-12 | 2019-02-22 | 中材科技股份有限公司 | A kind of acid leaching treatment method and preparation method of high silica glass fiber yarn rope |
| CA3128796A1 (en) * | 2019-02-22 | 2020-08-27 | Gebruder Dorfner Gmbh & Co. Kaolin- Und Kristallquarzsand-Werke Kg | Method for producing solid particles, solid particles, and the use thereof |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT352684B (en) * | 1975-06-13 | 1979-10-10 | Steirische Magnesit Ind Ag | PROCESS FOR PROCESSING NATURAL SILICATES |
-
1980
- 1980-06-27 AT AT0338780A patent/AT377958B/en not_active IP Right Cessation
-
1981
- 1981-06-02 DE DE3121920A patent/DE3121920C2/en not_active Expired
- 1981-06-26 NO NO812201A patent/NO160200C/en unknown
- 1981-06-29 GB GB8119975A patent/GB2078703B/en not_active Expired
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5302364A (en) * | 1991-12-25 | 1994-04-12 | R & D Silicate Products, Ltd. | Process for the preparation of amorphous silica |
| WO1995007235A1 (en) * | 1993-09-06 | 1995-03-16 | Svein Olerud | A method for manufacturing spherical silica from olivine |
| US5780005A (en) * | 1993-09-06 | 1998-07-14 | Olerud; Svein | Method for manufacturing spherical silica from olivine |
| US8110166B2 (en) | 2002-11-27 | 2012-02-07 | Silmag Da | Process for producing silica from olivine |
| WO2005068363A1 (en) | 2004-01-14 | 2005-07-28 | Cod Technologies A.S. | Process for production of precipitated silica from olivine |
| EP1598114A1 (en) * | 2004-05-18 | 2005-11-23 | Outreau Technologies | Method of separating silica and olivine from a mixture containing these substances and device for carrying out said method |
| FR2870467A1 (en) * | 2004-05-18 | 2005-11-25 | Outreau Technologies Soc Par A | METHOD FOR SEPARATING SILICA AND OLIVINE IN A CONTAINING MIXTURE AND DEVICE FOR IMPLEMENTING SAID METHOD |
| WO2007054955A1 (en) * | 2005-11-10 | 2007-05-18 | Council Of Scientific & Industrial Research | A process for the preparation of sodium silicate from kimberlite tailings |
| WO2016176772A1 (en) | 2015-05-06 | 2016-11-10 | Alliance Magnésium | Method for the production of amorphous silica with controlled specific surface area from magnesium silicate ore |
| CN107614431A (en) * | 2015-05-06 | 2018-01-19 | 联盟镁公司 | For the method by amorphous silica of the silicic acid magnesium ore production with controlled specific surface area |
| EA034324B1 (en) * | 2015-05-06 | 2020-01-28 | Алльянс Магнезиум | Method for the production of amorphous silica with controlled specific surface area from serpentine |
| AU2016257629B2 (en) * | 2015-05-06 | 2020-07-23 | Alliance Magnésium | Method for the production of amorphous silica with controlled specific surface area from magnesium silicate ore |
| US10752508B2 (en) | 2015-05-06 | 2020-08-25 | Alliance Magnésium Inc. | Method for the production of amorphous silica with controlled specific surface area from magnesium silicate ore |
| CN107614431B (en) * | 2015-05-06 | 2020-11-17 | 联盟镁公司 | Process for producing amorphous silica with controlled specific surface area from magnesium silicate ores |
Also Published As
| Publication number | Publication date |
|---|---|
| AT377958B (en) | 1985-05-28 |
| ATA338780A (en) | 1984-10-15 |
| DE3121920A1 (en) | 1982-04-29 |
| GB2078703B (en) | 1983-06-08 |
| NO160200C (en) | 1989-03-22 |
| NO160200B (en) | 1988-12-12 |
| NO812201L (en) | 1981-12-28 |
| DE3121920C2 (en) | 1985-01-17 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19950629 |