GB2053874A - Production of calcium sulfate - Google Patents
Production of calcium sulfate Download PDFInfo
- Publication number
- GB2053874A GB2053874A GB8015586A GB8015586A GB2053874A GB 2053874 A GB2053874 A GB 2053874A GB 8015586 A GB8015586 A GB 8015586A GB 8015586 A GB8015586 A GB 8015586A GB 2053874 A GB2053874 A GB 2053874A
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- GB
- United Kingdom
- Prior art keywords
- calcium sulfate
- type calcium
- process according
- anhydrite
- type
- 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.)
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- OSGAYBCDTDRGGQ-UHFFFAOYSA-L calcium sulfate Chemical compound [Ca+2].[O-]S([O-])(=O)=O OSGAYBCDTDRGGQ-UHFFFAOYSA-L 0.000 title claims abstract description 103
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 229910052925 anhydrite Inorganic materials 0.000 claims abstract description 13
- ZOMBKNNSYQHRCA-UHFFFAOYSA-J calcium sulfate hemihydrate Chemical compound O.[Ca+2].[Ca+2].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O ZOMBKNNSYQHRCA-UHFFFAOYSA-J 0.000 claims abstract description 13
- 239000007858 starting material Substances 0.000 claims abstract description 13
- 239000000463 material Substances 0.000 claims abstract description 11
- 238000001027 hydrothermal synthesis Methods 0.000 claims abstract description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 9
- 239000000203 mixture Substances 0.000 claims abstract description 8
- 239000012736 aqueous medium Substances 0.000 claims abstract description 7
- 238000001354 calcination Methods 0.000 claims abstract description 6
- 238000000034 method Methods 0.000 claims description 22
- 239000000126 substance Substances 0.000 claims description 15
- 239000002002 slurry Substances 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 7
- 239000002253 acid Substances 0.000 claims description 5
- 238000013019 agitation Methods 0.000 claims description 5
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 15
- 239000000835 fiber Substances 0.000 description 11
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 6
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 5
- 235000011054 acetic acid Nutrition 0.000 description 5
- 239000006227 byproduct Substances 0.000 description 5
- 229910052791 calcium Inorganic materials 0.000 description 5
- 239000011575 calcium Substances 0.000 description 5
- 238000006477 desulfuration reaction Methods 0.000 description 5
- 230000023556 desulfurization Effects 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 239000002904 solvent Substances 0.000 description 5
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 3
- 238000000227 grinding Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000003546 flue gas Substances 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 150000007522 mineralic acids Chemical class 0.000 description 2
- 150000007524 organic acids Chemical class 0.000 description 2
- 235000005985 organic acids Nutrition 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000011541 reaction mixture Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 description 1
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- BJEPYKJPYRNKOW-UHFFFAOYSA-N alpha-hydroxysuccinic acid Natural products OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 description 1
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 description 1
- 239000004327 boric acid Substances 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000007810 chemical reaction solvent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000011162 core material Substances 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 235000011187 glycerol Nutrition 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 239000001630 malic acid Substances 0.000 description 1
- 235000011090 malic acid Nutrition 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000011975 tartaric acid Substances 0.000 description 1
- 235000002906 tartaric acid Nutrition 0.000 description 1
Classifications
-
- 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
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/46—Sulfates
- C01F11/466—Conversion of one form of calcium sulfate to another
-
- 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
- C04B11/00—Calcium sulfate cements
- C04B11/02—Methods and apparatus for dehydrating gypsum
- C04B11/024—Ingredients added before, or during, the calcining process, e.g. calcination modifiers
-
- 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
- C09C1/02—Compounds of alkaline earth metals or magnesium
- C09C1/025—Calcium sulfates
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/54—Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension
-
- 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
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
-
- 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
Abstract
Alpha-type calcium sulfate hemihydrate is produced by a hydrothermal reaction at 90 DEG C or more of a calcium sulfate starting material in an aqueous medium in the presence of a powdery seed material comprising beta -type calcium sulfate hemihydrate, or soluble calcium sulfate anhydrite or a mixture thereof. The alpha -type calcium sulfate hemihydrate produced is in fibrous and/or spherical form. The alpha -type calcium sulfate hemihydrate is convertible to soluble or insoluble calcium sulfate anhydrite by calcination or to calcium sulfate dihydrate by contacting it with water.
Description
1 GB 2 053 874 A 1
SPECIFICATION Production of calcium sulfate
The invention relates to processes for the production of a-type calcium sulfate hernihydrate from calcium sulfate dihydrate, A-type calcium sulfate hemihydrate, soluble calcium sulfate anhydrite or a mixture of two or more thereof.
The invention comprises a process for the production of a-type calcium sulfate hernihydrate in a 5 fibrous form and/or a spherical form from a starting material comprising calcium sulfate dihydrate, A type calcium sulfate hemihydrate, soluble calcium sulfate anhydrite or a mixture of two or more thereof, the process comprising forming a slurry of the starting material in an aqueous medium, adding a powdery seed material comprising A-type calcium sulfate hemihydrate or soluble calcium sulfate anhydrite or a mixture thereof to the slurry at a temperature of 901C or more, and effecting a hvdrothermal reaction in the slurry under agitation.
The calcium sulfate starting material may be of any origin, so that any of natural calcium sulfate, chemically produced calcium sulfate, and calcium sulfate obtained as a by- product of desulfurization of flue gases can be used. The starting calcium sulfate is preferably from 0. 5 to 50 parts by weight, more preferably from 1 to 35 parts by weight, per 100 parts by weight of the aqueous medium.
The aqueous medium may be water or an aqueous solution of acid and/or an organic substance, Examples of suitable acids are organic acids such as formic acid, acetic acid, malic acid and tartaric acid and inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and boric acid. Suitable organic substances include ethylene glycol, diethyleneglycol and glycerine. Aqueous solutions of organic acids 20 preferably have a concentration of the acid of from 0.05 to 80 percent by weight, more preferably from 0.2 to 40 percent by weight; aqueous solutions of inorganic acids preferably have a concentration of the acid of from 0.01 to 50 percent by weight, more preferably from 0.05 to 20 percent by weight; aqueous solutions of organic substances preferably have a concentration of the organic substance of from 0.02 to 40 percent by weight, more preferably from 0A to 20 percent by weight.
The starting calcium sulfate is mixed with the aqueous medium to make a slurry, The slurry is then heated to at least 90'C and the powdery seed material, which preferably has a particle size of 1 Ou or less, is then added, preferably in an amount of from 0.00 1 to 50 parts by weight per 100 parts by weight of the starting calcium sulfate. Earlier addition of the A-type calcium sulfate hernihydrate and/or soluble calcium sulfate anhydrite would result in their hydration.
After addition of the seed material, the hydrothermal reaction is carried out, suitably at a temperature of from 100 to 1 800C, preferably from 105 to 140C, and usually under pressure. The hydrothermal reaction is carried out under agitation which can be effected in any manner. Agitation of the slurry becomes difficult when the amount of the starting calcium sulfate in the slurry is beyond the range given above. The hydrothermal reaction is desirably carried out for a period of from 1 to 90 minutes, preferably from 3 to 60 minutes. The method of effecting agitation is not critical so can be determined in view of factors such as the form and size of the reaction vessel and the kind of impeller.
The hydrothermal reaction yields a-type calcium sulfate hemihydrate in a fibrous form and/or a spherical form. The fibre length of the fibrous form is from 100 to 4001t. The spherical form, in which fibres of the fibrous form are intertwined, has a mean diameter of from 0. 01 to 10 mm and a bulk density of from 0.02 to 0.8 g/cc. 40 After the reaction is finished, solid-liquid separation may be effected to obtain the a-type calcium sulfate hemihydrate product. Solid-liquid separation is usually effected while the reaction mixture is hot, and the liquid may be re-used as reaction solvent.
The a-type calcium sulfate hemihydrate may be used as it is. It may, however, be con. verted to other states. In particular, it may be converted to soluble calcium sulfate anhydrite by calcination at about 2000C, or to insoluble calcium sulfate anhydrite by calcination at a temperature of from 500 to 1 OOOOC. Additionally, it may also be converted to calcium sulfate dihydrate by contacting it with water.
The method of the invention is convenient to carry out. Rigorous temperature control is not necessary. The reaction period is not long. A remarkable feature of the invention is that addition of the 50 powdery seed material enables spherical calcium sulfate to be obtained, even under conditions in which only fibrous calcium sulfate would be expected to form if the powdery seed material was not added. The resulting spherical calcium sulfate is homogeneous in particle size, and of low bulk density, and the fibrous calcium sulfate produced has a low diameter.
Calcium sulfate obtained by processes according to the invention is useful in construction 55 materials such as panels, heat insulating material and core material, as a filler for various plastics, and as an absorbent, filter aid or catalyst in the chemical industry. It is expected that it will also prove useful in agriculture.
The following Examples illustrate the invention.
EXAMPLES 1 TO 17 A glass autoclave of 300 mi capacity was charged with 210 mi of solvent (as detailed in Table 1) and with an amount (detailed in Table 1) of starting calcium sulfate (by-product at desulfurization process of flue gas of thermal power plant). The autoclave and its contents were heated under stirring at 2 GB 2 053 874 A 2 r.p.m. at a rate of about WC per minute up to 901C. Then a powdery inorganic substance (as detailed in Table 1) was added. Heating was continued to 120C at which temperature a hydrothermal reaction was carried out for 10 minutes. The reaction mixture was filtered while hot and the residue was washed with methanol to obtain the product. The results are shown in Table 1).
COMPARATIVE EXAMPLES 1 TO 4 A procedure similar to that described in Examples 1 to 17 was carried out except that calcium sulfate dihydrate was employed for starting material and no powdery inorganic substance was added. The results are shown in Table 1.
COMPARATIVE EXAMPLES 5 AND 6 A procedure similar to that described in Examples 1 to 17 was carried out except that calcium 10 sulfate consisting of 10% by weight of A-type calcium sulfate hernihydrate and 90% by weight of calcium sulfate dihydrate was employed for starting material, hydrated fully for one hour at 250C, and that no powdery inorganic substance was added. The results are shown in Table 1.
1 TABLE 1
Average Quantity1 Hemihy- Average 4 Average 5 Diameter of starting Powdery Inorganic Substances Bulk dration Fiber Fiber Aspect of Material Form of Density Rate Length Diameter Ratio Sphere (g/CM3) (Wt 0/ C Example Solvent (w t 0/0) Kind Grinding Amount2 Product3 0) L (IL) D (p) (L/ D) water 10 8-type cal- No 2 A B>> C 0.13 50 120 0.9 133 cium sulfate hemihydrate 2 10 5 5 5 A 0.08 88 80 0.7 114 3 10 Yes 5 A 0.08 85 90 0.4 225 4 09 10 9 5 No 10 A -B>> C 0.10 58 70 0.6 109 10 20 A. B>>C 0.11 83 35 0.5 70 6 20 1 5 A>B>C 0.14 61 55 0.3 162 7 10 calcium, sul- 5 A. B>> C 0.13 56 120 0.3 400 fate, by product of the desulfurization process; (treated at 1100C for 5 hrs) 93 20 23 10 A>B>C 0.13 80 75 0.3 259 99 20 29 2 py 0.13 70 40 0.8 47 (treated at.
OC for 5 hrs) 19 20 is pp 5 52 0.12 81 20 0.6 34 6 C0 NJ 0 al W 00 j P.
W -Ph TABLE 'I (Continued) Average Quantity 1 Hemihy- Average4 Average5 Diameter of starting Powdery Inorganic Substances Bulk dration Fiber Fiber Aspect of Material Form of Density Rate Length Diameter Ratio Sphere Example Solvent (wt 0/0) Kind Grinding Amount2 Product3 (g/cw) (Wt %) L (p) D (y) (L/1)) (0 0.'5 wt % 10 8-type cal- No 2 A>D 0.08 78 40 0.6 67 of aque- cium sulfate ous Sol u- hernihydrate tion of acetic acid 12 99 10 so so 5 D >> A 0.09 93 0.6 310 13 09 10 91 50 10, A > D 0.09 92 47 0.4 134 14 97 20 92 is 5 D > A >>'C 0.16 50 0.6 200 99 20 calcium sul- 99 2 D.A >> C 0.13 87 55 0.7 82 fate, by- product of the desulfurization process; (treated at 1500C for 5 hrs) 16 99 20 99 5 so 0.12 89 60 0.6 109 17 53 20 39 10 A > D. B 0.13 100 40 0.6 68 Compara- water 10 None 0 unchanged 1.10 tive Ex. 1 as C 37 2 39 20 95 - 0 30 4 '? 1.10 P.
1 1, ul TABLE 1 (Continued) Average Quantity1 Hemihy- Average4 Average5 Diameter of Starting Powdery Inorganic Substances Bulk dration Fiber Fiber Aspect of Material - Form, of Density Rate Length Diameter Ratio Sphere Example Solvent (wt %) Kind Grinding Amount2 Product3 (g_CM 3) (Wt %) L (IL) D (tt) (L/D) (it) Compara- 0.5 wt % 10 None 0 A>D>C 0.11 47 100 0.6 167 tive Ex. 3 of aque ous sol U tion of acetic acid 19 4 20 0 unchanged 1.10 as C water 10 is - 0 A. D.C 0.20 25 50 0.6 84 it 6 0.5 wt % 10 0 D>A 0.09 71 0.6 440 of aque ous solu tion of z acetic acid a) C5 P1) 0 (n W OD j _Ph 01 6 GB 2 053 874 A 6 Note.:
1. amount of starting material - starting material X 100 (wt 0/0) solvent + starting material 2. amount of powdery inorganic substance inorganic substance X 100 (wt 0/0) starting material 3. form of product 6 > 4; 9 >> 1 rough state (photographs by optical microscope, mag, 50:1) A: fiber, B: bur, C: starting material, D: sphere 4. average fiber length photographs by universal projector (mag. 50: 1) 100 pieces 5. average fiber diameter photographs by electron microscope (mag. 30001:1y 50 pieces EXAMPLES 18 TO 26 A tower reactor (length 5.5 m, internal diameter of 32 mm) was used and the hydrothermal reaction was carried out under the conditions detailed in Table IL After the reaction, the mixture was filtered while hot and the residue was washed with methanol 5 to obtain the product. The product was dried at 601C for 3 hours to give fibrous a-type calcium sulfate hernihydrate and/or spherical a-type calcium sulfate hernihydrate formed by intertwining of the fibrous a-type calcium sulfate hernihydrate. The results are shown in Table 11.
TABLE 11
Powdery Reaction Amount Average Average Hemihy- Solvent1 Starting Inorganic Tempera- of Diameter Fiber Bulk dration (100 Vol. Calcium Substance ture Feed of Sphere Diameter Density Rate Example part) Sulfate (wt. part) (OC) (1/hr) ' (mm) (mm) (g / cm') M Remark2 18 water calcium 5 8-type cal-: 1 136 54 0.30 0.09 100 sulfate cium sulfate d1hydrate hem1hydrate 19 11 1 g 5 Y 9 1 9 9 3 3 0,30 0.25 0.12 1 1 0.5 wt. % 11 5 P, 0.5 99 19 P% 0.28 0.10 S, 0 = of aqueous solution of acetic acid 21 11 5 09 1 99 11 51 0.25 0.095 ty @ 22 5 17 1 19 99 0.25 99 31 0 23 2.5 91 0.25 so 79 0.35 0.20 0.16 @ 24 2.5 is 0.5 is 54 so 0.25 0.15 @ 10 15 0.5 93 0.30 $1 0.10 @ 26 10 99 1 30 0.35 35 0.13 @ T: calcium sulfate, by-product of the desulfurization process.
Z:@ spherical, excellent; o spherical, average; = fibrous only,; o = a mixture of fibrous and spherical.
G) m hi 0 cn W 00 4.P.
I.i 8 GB 2 053 874 A 8
Claims (7)
1. A process for the production of a-type calcium sulfate hemihydrate in a fibrous form and/or a spherical form from a starting material comprising calcium sulfate dihydrate, P-type calcium sulfate hemihydrate, soluble calcium sulfate anhydrite or a mixture of two or more thereof, the process comprising forming a slurry of the starting material in an aqueous medium, adding a powdery seed material comprising P-type calcium sulfate hernihydrate or soluble calcium sulfate anhydrite or a mixture thereof to the slurry at a temperature of 901C or more, and effecting a hydrothermal reaction in the slurry under agitation.
2. A process according to claim 1 in which the hydrothermal reaction is carried out at a temperature of from 1 00C to 1 801C.
3. A process according to either preceding claim in which the aqueous medium is water or an aqueous solution of an acid and/or an organic substance.
4. A process according to any of claims 1 to 3 further comprising calcining a-type calcium sulfate hernihydrate to convert it to calcium sulfate anhydrite.
15,
5. A process according to claim 4 in which the calcination is carried out at a temperature of about 15 2000C to form soluble calcium sulfate anhydrite.
6. A process according to claim 4 in which the calcination is carried out at a temperature of from 500 to 1 OOOOC to form insoluble calcium sulfate anhydrite.
7. A process according to any of claims 1 to 3 further comprising contacting a-type calcium sulfate hernihydrate with water to form calcium sulfate dihydrate.
S. A process for the production of a-type calcium sulfate hemihydrate, the process being substantially as described herein with reference to the Examples.
printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1981. Published by the Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained.
1 li- 1
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP15945577A JPS5499098A (en) | 1977-12-29 | 1977-12-29 | Production of satin spar gypsum or spherical gypsum formed from said gypsum |
| JP8096778A JPS5510406A (en) | 1978-07-05 | 1978-07-05 | Production of gypsum |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2053874A true GB2053874A (en) | 1981-02-11 |
| GB2053874B GB2053874B (en) | 1982-07-28 |
Family
ID=26421929
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7848753A Expired GB2011363B (en) | 1977-12-29 | 1978-12-15 | Production of calcium sulphate |
| GB8015586A Expired GB2053874B (en) | 1977-12-29 | 1978-12-15 | Production of calcium sulphate |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7848753A Expired GB2011363B (en) | 1977-12-29 | 1978-12-15 | Production of calcium sulphate |
Country Status (5)
| Country | Link |
|---|---|
| CA (1) | CA1115025A (en) |
| DE (1) | DE2854722C2 (en) |
| FR (1) | FR2413339B1 (en) |
| GB (2) | GB2011363B (en) |
| IT (1) | IT1158192B (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4664707A (en) * | 1985-04-09 | 1987-05-12 | Georgia-Pacific Corporation | Fire resistant gypsum composition |
| US4722866A (en) * | 1985-04-09 | 1988-02-02 | Georgia-Pacific Corporation | Fire resistant gypsum board |
| US4818287A (en) * | 1982-05-19 | 1989-04-04 | Georgia-Pacific Corporation | Fiber reinforced plaster molds for metal casting |
| WO1990011256A1 (en) * | 1989-03-16 | 1990-10-04 | The United States Gypsum Company | Process and apparatus for producing calcium sulfate microfibers |
| US5148645A (en) * | 1984-02-27 | 1992-09-22 | Georgia-Pacific Corporation | Use of fibrous mat-faced gypsum board in shaft wall assemblies and improved fire resistant board |
| US5401588A (en) * | 1992-12-23 | 1995-03-28 | Georgia-Pacific Resins Inc. | Gypsum microfiber sheet material |
| EP2338856A3 (en) * | 2009-10-02 | 2011-10-05 | Cemex Research Group AG | Process for anhydrite preparation for the manufacturing of a mortar. |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3615717A1 (en) * | 1986-05-09 | 1987-11-12 | Benckiser Gmbh Joh A | METHOD FOR THE HYDROTHERMAL CONVERSION OF SMOKE GAS DESULFURATION PLASTER IN CALCIUM SULFATE (ALPHA) HEMIHYDRATE |
| FR2856679B1 (en) * | 2003-06-26 | 2006-12-22 | Couturier Jean | PROCESS FOR PREPARING ANHYDRITE III STABILIZED FROM PLASTER |
| CN105980329B (en) * | 2013-12-06 | 2018-03-30 | 佐治亚-太平洋石膏有限责任公司 | Composite gypsum material modifying agent |
| CN106061919A (en) * | 2013-12-06 | 2016-10-26 | 佐治亚-太平洋石膏有限责任公司 | Gypsum composite modifiers |
Family Cites Families (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1356700A (en) * | 1963-05-10 | 1964-03-27 | Giulini Gmbh Soc Geb | Process for the production of high quality semi-hydrated plasters |
| GB1079502A (en) * | 1963-05-28 | 1967-08-16 | Cafferata & Co Ltd | Improvements in and relating to the production of calcium sulphate hemihydrate |
| GB1051849A (en) * | 1963-12-03 | |||
| GB1248037A (en) * | 1968-01-13 | 1971-09-29 | Fisons Ltd | Calcium sulphate |
| US3822340A (en) * | 1972-03-27 | 1974-07-02 | Franklin Key | Calcium sulfate whisker fibers and the method for the manufacture thereof |
| JPS593406B2 (en) * | 1974-05-15 | 1984-01-24 | 三菱重工業株式会社 | Alpha-Gatahansuisetsukou |
| US4029512A (en) * | 1974-08-05 | 1977-06-14 | Johns-Manville Corporation | Method for the preparation of fibrous insoluble calcium sulfate anhydrite |
| JPS5248594A (en) * | 1975-10-17 | 1977-04-18 | Kureha Chem Ind Co Ltd | Method for producing type gypsum hemihydrate |
| JPS52156199A (en) * | 1976-06-22 | 1977-12-26 | Onoda Cement Co Ltd | Production of gypsum fiber |
| DE2729842B2 (en) * | 1977-07-01 | 1979-05-23 | Skw Trostberg Ag, 8223 Trostberg | Process for the production of inorganic fibers based on calcium sulfate |
-
1978
- 1978-12-15 GB GB7848753A patent/GB2011363B/en not_active Expired
- 1978-12-15 GB GB8015586A patent/GB2053874B/en not_active Expired
- 1978-12-19 DE DE2854722A patent/DE2854722C2/en not_active Expired
- 1978-12-19 CA CA318,237A patent/CA1115025A/en not_active Expired
- 1978-12-27 IT IT52460/78A patent/IT1158192B/en active
- 1978-12-27 FR FR7836549A patent/FR2413339B1/en not_active Expired
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4818287A (en) * | 1982-05-19 | 1989-04-04 | Georgia-Pacific Corporation | Fiber reinforced plaster molds for metal casting |
| US5148645A (en) * | 1984-02-27 | 1992-09-22 | Georgia-Pacific Corporation | Use of fibrous mat-faced gypsum board in shaft wall assemblies and improved fire resistant board |
| US4664707A (en) * | 1985-04-09 | 1987-05-12 | Georgia-Pacific Corporation | Fire resistant gypsum composition |
| US4722866A (en) * | 1985-04-09 | 1988-02-02 | Georgia-Pacific Corporation | Fire resistant gypsum board |
| WO1990011256A1 (en) * | 1989-03-16 | 1990-10-04 | The United States Gypsum Company | Process and apparatus for producing calcium sulfate microfibers |
| US5401588A (en) * | 1992-12-23 | 1995-03-28 | Georgia-Pacific Resins Inc. | Gypsum microfiber sheet material |
| EP2338856A3 (en) * | 2009-10-02 | 2011-10-05 | Cemex Research Group AG | Process for anhydrite preparation for the manufacturing of a mortar. |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2413339A1 (en) | 1979-07-27 |
| FR2413339B1 (en) | 1985-11-08 |
| IT7852460A0 (en) | 1978-12-27 |
| DE2854722C2 (en) | 1985-09-19 |
| CA1115025A (en) | 1981-12-29 |
| GB2011363B (en) | 1982-07-14 |
| GB2011363A (en) | 1979-07-11 |
| IT1158192B (en) | 1987-02-18 |
| DE2854722A1 (en) | 1979-07-05 |
| GB2053874B (en) | 1982-07-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |