CA1077245A - Process for preparing shaped articles from gypsum - Google Patents
Process for preparing shaped articles from gypsumInfo
- Publication number
- CA1077245A CA1077245A CA232,971A CA232971A CA1077245A CA 1077245 A CA1077245 A CA 1077245A CA 232971 A CA232971 A CA 232971A CA 1077245 A CA1077245 A CA 1077245A
- Authority
- CA
- Canada
- Prior art keywords
- weight
- gypsum
- calcium sulphate
- resp
- process according
- 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
- 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
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/14—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements
- C04B28/141—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing calcium sulfate cements containing dihydrated gypsum before the final hardening step, e.g. forming a dihydrated gypsum product followed by a de- and rehydration step
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Devices For Post-Treatments, Processing, Supply, Discharge, And Other Processes (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Process for prop preparing shaped articles from gypsum (CaSO4.2H2O),by compressing calcium sulphate dihydrate and additives to form articles.
The process is characterized in that in moist, non-calcined calcium sulphate dihydrate of any origin one or several addivites, with the exception of calcium sulphate hemihydrate, is admixed and the gypsum slurry compressed at a pressure of at least 200 kg/cm2 and thereafter dried.
Chemical gypsum containing soluble phasphates, fluorides and/or ammonium sulphate up to about 2% by weight or cement the ground blast-furnace sing in a quantity of up to 10% by weight, referred to the dry gypsum is started form. Preferred as a additive is urea formaldehyde resin in a quantity of less than 3% by weight referred to the dry gypsum, preferably 1-4% by weight, and more preferably approximately 1% by weight in the combination of chemical gypsum of acid reaction.
Process for prop preparing shaped articles from gypsum (CaSO4.2H2O),by compressing calcium sulphate dihydrate and additives to form articles.
The process is characterized in that in moist, non-calcined calcium sulphate dihydrate of any origin one or several addivites, with the exception of calcium sulphate hemihydrate, is admixed and the gypsum slurry compressed at a pressure of at least 200 kg/cm2 and thereafter dried.
Chemical gypsum containing soluble phasphates, fluorides and/or ammonium sulphate up to about 2% by weight or cement the ground blast-furnace sing in a quantity of up to 10% by weight, referred to the dry gypsum is started form. Preferred as a additive is urea formaldehyde resin in a quantity of less than 3% by weight referred to the dry gypsum, preferably 1-4% by weight, and more preferably approximately 1% by weight in the combination of chemical gypsum of acid reaction.
Description
7;~45 The invention relates to a process for preparing shaped articles from gypsum (CaS04.2H20), by compressing calcium sulphate dihydrate and additives to form shaped articles.
It is known that shaped articles consisting of gypsum can be prepared in the above-mentioned way. Apart from the many additives, such as setting accelerators, setting retarders or binding agents, then used, CaSO4 1/2 H20 is - at least in part - invariably used, as described, for instance, in German Patent Specification 2,240,926.
It has appeared that, contrary to the general view, the use of CaS04.1/2 H20 is not at all necessary to obtain sufficiently strong shaped articles from CaS04. 2 H20 of any origin whatever if an adequate compression pressure is applied.
The invention therefore relates to a process for the preparation of shaped articles from gypsum ~CaS04.2 H20) by compressing calcium sulphate dihydrate and additives to form articles, the process being characterized in that moist, non-calcined calcium sulphate dihydrate is admixed with at least one of the additives chosen from the group of additives consisting of soluble phosphate, fluorides and ammonium sulphate in an amount up to about
It is known that shaped articles consisting of gypsum can be prepared in the above-mentioned way. Apart from the many additives, such as setting accelerators, setting retarders or binding agents, then used, CaSO4 1/2 H20 is - at least in part - invariably used, as described, for instance, in German Patent Specification 2,240,926.
It has appeared that, contrary to the general view, the use of CaS04.1/2 H20 is not at all necessary to obtain sufficiently strong shaped articles from CaS04. 2 H20 of any origin whatever if an adequate compression pressure is applied.
The invention therefore relates to a process for the preparation of shaped articles from gypsum ~CaS04.2 H20) by compressing calcium sulphate dihydrate and additives to form articles, the process being characterized in that moist, non-calcined calcium sulphate dihydrate is admixed with at least one of the additives chosen from the group of additives consisting of soluble phosphate, fluorides and ammonium sulphate in an amount up to about
2% by weight, urea formaldehyde resin in an amount up to 5% by weight and . 20 cement and ground blast-furnace slag in an amount up to 10% by weight, all ; amounts referred to the dry gypsum, the mixture compressed to a pressure of at least 200 kg/cm2 and the moulded mixture then allowed to dry under conditions at which calcium sulphate hemihydrate is not formed from the dihydrate.
According to the process of the invention, therefore, one may simply start from chemical gypsum, which is formed during the dissolution of apatite, either with sulphuric acid or with nitric acid, subsequent to which the gypsum precipitates. The wet gypsum, containing about 30%
by weight of free water, impurified by organic material, soluble phosphates, fluorides and/or ammonium sulphate, may, if desired with use of .
- , .
1(~77Z4S
known additieves, be compressed according to the 'wet compression method' mentioned below to ~orm shaped articles. The water (together with part o~ said substances) is i'orced out; a shaped article having a water content oi', i'or instance, 12 % by weight is obtained at a compression pressure oi 300 ~g/cm2.
A compression method which is more rapid and more i'easible in practice i5 achieved by proceeding according to the so-called 'dry compression method.. According to this method the gypsum slurry, which contains about 30 % oi' i'ree water, is i'irst de-watered by means oi' i'iltration, i~ necessary supported by the action oi hydrocy¢lones, until the gypsum contains 10 to 20 % by weight o~ ~ree water, to which gypsum subsequently a binding agent in liquid or solid state is added. During the subsequent compression oi' the gypsum mass hardly any water is released.
Finally, in either case the remainder oi water is removed with I5 heating at 80 low a temperature that no hemihydrate is i'ormed, i'or instance at 50 &. However, also drying at room temperature and a sui~iciently lo~ degree oi' humidity i'or a longer period o~ time is possible.
The ultimate strength o~ the dried shaped articles is a ~unction oi the compression pressure, as i9 indicated in more detail in the Tables.
In order that the breaking strength oi' the shaped articles agree with the values required the most, in this respect, ~or use as building material, prei'eren~e is given to application oi' a compression pressure oi at least 200 kg/cm . It is necessary that the liquid eo~ains such a quantity oi' dissolved additives that, ai'ter part ôi' them has been iorced out, the dried shaped article still contains 1 to about 2 % by weight o~ such additives rei'erred to the dry gypsum. As the known additives hydrosilicoi'luoride and a~monium sulphate are highly suitable. Other additives are not excluded.
The substance i'irst mentioned iorms during the dissolution oi' apatite and, according to the process of the invention, need not be spæially removed .. .. .
~rom the gypsum mass. Depending on the dissolution process, the second substance may still be present in the gypsum slurry to a small extent.
According to the process of the invention, therefore, one may simply start from chemical gypsum, which is formed during the dissolution of apatite, either with sulphuric acid or with nitric acid, subsequent to which the gypsum precipitates. The wet gypsum, containing about 30%
by weight of free water, impurified by organic material, soluble phosphates, fluorides and/or ammonium sulphate, may, if desired with use of .
- , .
1(~77Z4S
known additieves, be compressed according to the 'wet compression method' mentioned below to ~orm shaped articles. The water (together with part o~ said substances) is i'orced out; a shaped article having a water content oi', i'or instance, 12 % by weight is obtained at a compression pressure oi 300 ~g/cm2.
A compression method which is more rapid and more i'easible in practice i5 achieved by proceeding according to the so-called 'dry compression method.. According to this method the gypsum slurry, which contains about 30 % oi' i'ree water, is i'irst de-watered by means oi' i'iltration, i~ necessary supported by the action oi hydrocy¢lones, until the gypsum contains 10 to 20 % by weight o~ ~ree water, to which gypsum subsequently a binding agent in liquid or solid state is added. During the subsequent compression oi' the gypsum mass hardly any water is released.
Finally, in either case the remainder oi water is removed with I5 heating at 80 low a temperature that no hemihydrate is i'ormed, i'or instance at 50 &. However, also drying at room temperature and a sui~iciently lo~ degree oi' humidity i'or a longer period o~ time is possible.
The ultimate strength o~ the dried shaped articles is a ~unction oi the compression pressure, as i9 indicated in more detail in the Tables.
In order that the breaking strength oi' the shaped articles agree with the values required the most, in this respect, ~or use as building material, prei'eren~e is given to application oi' a compression pressure oi at least 200 kg/cm . It is necessary that the liquid eo~ains such a quantity oi' dissolved additives that, ai'ter part ôi' them has been iorced out, the dried shaped article still contains 1 to about 2 % by weight o~ such additives rei'erred to the dry gypsum. As the known additives hydrosilicoi'luoride and a~monium sulphate are highly suitable. Other additives are not excluded.
The substance i'irst mentioned iorms during the dissolution oi' apatite and, according to the process of the invention, need not be spæially removed .. .. .
~rom the gypsum mass. Depending on the dissolution process, the second substance may still be present in the gypsum slurry to a small extent.
- 3 -10'~'7~5 The invention i9 elucidated by means oi the ~ollowing tables. The process according to the lnvention i9 here applied to small 5 x 5 x 5 cm cubes, In all cases chemical gypsum iq started ~rom, which has been obtained by dissolution oi' apatite with sulphuric acid, Table I: 'Wet compression method' __ Additives: ammonium sulphate, hydrosilicoiluoride compression breaking additive, denslty press~re stren~th % by w.
kg/cm kg/cm~
100 145 and 100 resp~ 1.65 and 1,39 resp. 1.50 and 1.46 resp.
200 ' 160 and 180 resp, 1.58 and 1.01 resp. 1.61 and 1.57 resp.
300 238 and 215 resp. 1.15 and 0.76 resp, 1,70 and'1,68 resp, 400 295 and 215 resp. 1.22 and 0.56 resp. 1.77 and 1.71 resp, 500 308 and 260 resp. 1.12 and 0.51 resp. 1.80 and 1.76 resp.
600 325 and 260 resp. 1.17 and 0.51 resp. 1.81 and 1.77 resp.
,' ' 700 330 and 270 resp. - resp. - - resp.
Table II: 'Dry compression method' . _ Additives: ammonium sulphate, hydrosillcoiluorlde -compresslon breaking addltive denslty ; pressure strength % by w.
kg/cm2 kg/cm2 ~, 100 92 and 95 resp. 1.90 and 1.90 r0sp, 1.49 and 1.46 resp, ' 200 172 and 148 resp. 1.54 and 1,64 resp. 1.57 and 1,57 resp.
'~ 300 202 and 177 resp. 1.38 and 1.38 resp. 1.66 and 1.63 resp, " 400 220 and 215 resp, 1.18 and 1.18 resp, 1.74 and 1,70 resp.
'l 500 307 and 235 resp, 1.10 and 1, lo resp, 1,77 and 1,75 resp.
600 332 and 320 resp. 1.06 and 1.06 resp. 1.83 and 1.82 r0sp.
700 343 and 332 resp. - resp. - resp.
3~ ~ re s j~. = r~ S;~e c A ~ e /,,~
. .
:: I
1~77245 The shaped articles prepared according to the process oi the in~ention are highly suitable as building material in places where they are not exposed directly to moisture. So-called 'blooming' as a result o~ the presence o~ sodium ions does not occur, since sodium ions are not present either in the impure gypsum slurry or ln the additives.
The process according to the invention brings great advantages because an environment-taxing by-product, viz. chemical gyp~um, whlch could so far only be rendered suitable ~s a building material in a more or less complicated manner, can now be processed to a well-usable product in a simple, relatively cheap manner.
For additive, also other substances than those mentioned above may be used, notably urea i'ormaldehyde resin, cement or ground blast-iurnace slag. Other substances, however, are not excluded, The rule applies, though, that the quantities to be added are sunstantially smaller than those applied to bind inorganic substances other than gypsum -(CaS04.2 ~ O), such as sand, chalk or marl, to ~orm su~iciQntly strong shap~d articles with applioation oi' pressure.
, Ii urea iormaldehyde resin is applied, less than 5 % by weight reierred to the dry gypsum will quii'ice; 1 to 4 % by weight, preierably even approximately 1 % by weight, re~erred to the dry gypsum, is quite ; satisi'actory.
Besides the iact that with use o~ a small am~unt oi urea ~or-maldehyde resin one may also start exclusively irom wet calcium sulphate dihydrate i'or basic material, the use oi' said resin as additive involves the advantage that the moisture resistance oi' i'inished shaped articles is considerably improved compared with i'inished shaped articles i'or ~hich ammonium sulphate or hydrosilico~luoride has been used as additive.
In the latter case the oompressive 3trength strongly decreas6s during a prolonged stay in an environment with a high relative humidity, i'or instance to less than 50 kg/cm . This is not the case ii urea i'ormaldehyde resin is used as additive, so that the shaped articles can be used as a lO~z4~
substitute ior llme sandstone. Table III ~hows results obtained with use oi' only 1 % by weight oi' urea i'ormaldehyde resln, ~tartlng i'rom the chemicalgyp~um reierred to prevlously and the ~o-called 'dry compresslon method'.
Table III: 'Dry compression method' ~, , Additive: urea i'ormaldehyde resin ~Al~Z0, type 6) 1 % by weight . , .
compression breaking 2 rO by weight oi' i'inal pressure strength kg/cm molsture density kg/cm2 absorbed aiter aiter drylng dryiOng at and 2 weeks at C rel humidlty oi 83 %
., .
' 100 60 60 0.035 1.48 ; 200 105 llS 0.044 1.60 300 lSS 147 0.065 1.6~
-' 400 174 l9S 0.083 1.73 :'i S00 203 195 0,063 1.70 ,i 600 280 202 0.051 1.72 ' ' .:
The table shows that ii' the shaped articles dorlng their stay ~2~e exposed to a hlgh relatlve humldlty the br~klng strength ls not ''l '~ ai'iected detrlmentally, whlch 18 not lnvarlably the ease when the other additlves are applied. The combination oi' chemical gypsum and urea iormaldehyde resin is extremely i'avourable, seeir4 that chemical gypsum, ; oi acid reactlon, with a pH value oi' about 5 has a strongly catalyzing eiiect !
on the urea iormaldehyde.
. ~ .
li cement or ground blast-$urnace slag ls applledj less than 10 %
-;l by weight re~er.red to the dry gypsum will suiiice. This quantity, too, is substantially lower than that necessary ior bindlng lnorganlc substances ~l other gypsum.
.:
: .1 ... .
. .
''' ': '' ;: .
: :
kg/cm kg/cm~
100 145 and 100 resp~ 1.65 and 1,39 resp. 1.50 and 1.46 resp.
200 ' 160 and 180 resp, 1.58 and 1.01 resp. 1.61 and 1.57 resp.
300 238 and 215 resp. 1.15 and 0.76 resp, 1,70 and'1,68 resp, 400 295 and 215 resp. 1.22 and 0.56 resp. 1.77 and 1.71 resp, 500 308 and 260 resp. 1.12 and 0.51 resp. 1.80 and 1.76 resp.
600 325 and 260 resp. 1.17 and 0.51 resp. 1.81 and 1.77 resp.
,' ' 700 330 and 270 resp. - resp. - - resp.
Table II: 'Dry compression method' . _ Additives: ammonium sulphate, hydrosillcoiluorlde -compresslon breaking addltive denslty ; pressure strength % by w.
kg/cm2 kg/cm2 ~, 100 92 and 95 resp. 1.90 and 1.90 r0sp, 1.49 and 1.46 resp, ' 200 172 and 148 resp. 1.54 and 1,64 resp. 1.57 and 1,57 resp.
'~ 300 202 and 177 resp. 1.38 and 1.38 resp. 1.66 and 1.63 resp, " 400 220 and 215 resp, 1.18 and 1.18 resp, 1.74 and 1,70 resp.
'l 500 307 and 235 resp, 1.10 and 1, lo resp, 1,77 and 1,75 resp.
600 332 and 320 resp. 1.06 and 1.06 resp. 1.83 and 1.82 r0sp.
700 343 and 332 resp. - resp. - resp.
3~ ~ re s j~. = r~ S;~e c A ~ e /,,~
. .
:: I
1~77245 The shaped articles prepared according to the process oi the in~ention are highly suitable as building material in places where they are not exposed directly to moisture. So-called 'blooming' as a result o~ the presence o~ sodium ions does not occur, since sodium ions are not present either in the impure gypsum slurry or ln the additives.
The process according to the invention brings great advantages because an environment-taxing by-product, viz. chemical gyp~um, whlch could so far only be rendered suitable ~s a building material in a more or less complicated manner, can now be processed to a well-usable product in a simple, relatively cheap manner.
For additive, also other substances than those mentioned above may be used, notably urea i'ormaldehyde resin, cement or ground blast-iurnace slag. Other substances, however, are not excluded, The rule applies, though, that the quantities to be added are sunstantially smaller than those applied to bind inorganic substances other than gypsum -(CaS04.2 ~ O), such as sand, chalk or marl, to ~orm su~iciQntly strong shap~d articles with applioation oi' pressure.
, Ii urea iormaldehyde resin is applied, less than 5 % by weight reierred to the dry gypsum will quii'ice; 1 to 4 % by weight, preierably even approximately 1 % by weight, re~erred to the dry gypsum, is quite ; satisi'actory.
Besides the iact that with use o~ a small am~unt oi urea ~or-maldehyde resin one may also start exclusively irom wet calcium sulphate dihydrate i'or basic material, the use oi' said resin as additive involves the advantage that the moisture resistance oi' i'inished shaped articles is considerably improved compared with i'inished shaped articles i'or ~hich ammonium sulphate or hydrosilico~luoride has been used as additive.
In the latter case the oompressive 3trength strongly decreas6s during a prolonged stay in an environment with a high relative humidity, i'or instance to less than 50 kg/cm . This is not the case ii urea i'ormaldehyde resin is used as additive, so that the shaped articles can be used as a lO~z4~
substitute ior llme sandstone. Table III ~hows results obtained with use oi' only 1 % by weight oi' urea i'ormaldehyde resln, ~tartlng i'rom the chemicalgyp~um reierred to prevlously and the ~o-called 'dry compresslon method'.
Table III: 'Dry compression method' ~, , Additive: urea i'ormaldehyde resin ~Al~Z0, type 6) 1 % by weight . , .
compression breaking 2 rO by weight oi' i'inal pressure strength kg/cm molsture density kg/cm2 absorbed aiter aiter drylng dryiOng at and 2 weeks at C rel humidlty oi 83 %
., .
' 100 60 60 0.035 1.48 ; 200 105 llS 0.044 1.60 300 lSS 147 0.065 1.6~
-' 400 174 l9S 0.083 1.73 :'i S00 203 195 0,063 1.70 ,i 600 280 202 0.051 1.72 ' ' .:
The table shows that ii' the shaped articles dorlng their stay ~2~e exposed to a hlgh relatlve humldlty the br~klng strength ls not ''l '~ ai'iected detrlmentally, whlch 18 not lnvarlably the ease when the other additlves are applied. The combination oi' chemical gypsum and urea iormaldehyde resin is extremely i'avourable, seeir4 that chemical gypsum, ; oi acid reactlon, with a pH value oi' about 5 has a strongly catalyzing eiiect !
on the urea iormaldehyde.
. ~ .
li cement or ground blast-$urnace slag ls applledj less than 10 %
-;l by weight re~er.red to the dry gypsum will suiiice. This quantity, too, is substantially lower than that necessary ior bindlng lnorganlc substances ~l other gypsum.
.:
: .1 ... .
. .
''' ': '' ;: .
: :
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Process for the preparation of shaped articles from gypsum (CsSO4.2H2O) by compressing calcium sulphate dihydrate and additives to form articles, the process being characterized in that moist, non-calcined calcium sulphate dihydrate is admixed with at least one of the additives chosen from the group of additives consisting of soluble phosphates, fluorides and ammonium sulphate in an amount up to about 2%
by weight, urea formaldehyde resin in an amount up to 5% by weight and cement and ground blast-furnace slag in an amount up to 10% by weight, all amounts referred to the dry gypsum, the mixture compressed to a pressure of at least 200 kg/cm2 and the moulded mixture then allowed to dry under conditions at which calcium sulphate hemihydrate is not formed from the dihydrate.
by weight, urea formaldehyde resin in an amount up to 5% by weight and cement and ground blast-furnace slag in an amount up to 10% by weight, all amounts referred to the dry gypsum, the mixture compressed to a pressure of at least 200 kg/cm2 and the moulded mixture then allowed to dry under conditions at which calcium sulphate hemihydrate is not formed from the dihydrate.
2. Process according to claim 1, characterized in that the non-calcined calcium sulphate dihydrate is chemical gypsum containing constituents from the group soluble phosphates, fluorides and ammonium sulphate.
3. Process according to claim 1 characterized in that the moist non-calcined calcium sulphate dihydrate is first de-watered to 10 to 20%
by weight of free water.
by weight of free water.
4. Process according to claim 3 characterized in that for additive urea formaldehyde resin is used in a quantity of 1-4% by weight.
5. Process according to claim 3 characterized in that for additive urea formaldehyde resin is used in a quantity of 1% by weight.
6. Process according to claim 1 or 4 characterized in that the chemical gypsum is from acid reaction with apatite.
7. Process according to claim 1 or 3 characterized in that, for the additive, cement or ground blast-furnace slag is used.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL7410706A NL7410706A (en) | 1974-08-09 | 1974-08-09 | PROCESS FOR MANUFACTURING FORMINGS FROM GIPS. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1077245A true CA1077245A (en) | 1980-05-13 |
Family
ID=19821890
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA232,971A Expired CA1077245A (en) | 1974-08-09 | 1975-08-06 | Process for preparing shaped articles from gypsum |
Country Status (12)
| Country | Link |
|---|---|
| JP (1) | JPS5145120A (en) |
| BE (1) | BE832152A (en) |
| BR (1) | BR7505111A (en) |
| CA (1) | CA1077245A (en) |
| DE (1) | DE2535577A1 (en) |
| ES (1) | ES440142A1 (en) |
| FR (1) | FR2281202A1 (en) |
| GB (1) | GB1479804A (en) |
| IT (1) | IT1041174B (en) |
| NL (1) | NL7410706A (en) |
| PL (1) | PL112807B1 (en) |
| ZA (1) | ZA755010B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL7604948A (en) * | 1976-05-08 | 1977-11-10 | Stamicarbon | PROCESS FOR MANUFACTURING FORMINGS FROM CALCIUM SULPHATE DIHYDRATE. |
| SU863537A1 (en) * | 1977-04-27 | 1981-09-15 | Ростовский Филиал Производственно-Технического Объединения "Росоргтехстром" | Method of making gypsum articles |
| FR2462402A1 (en) * | 1979-08-03 | 1981-02-13 | Setec Geotechnique | METHOD FOR MANUFACTURING CONSTRUCTION ELEMENTS FROM HYDRATED CALCIUM SULPHATE, CALCIUM PHOSPHATE TREATMENT RESIDUE |
| FI59872C (en) * | 1979-12-21 | 1981-10-12 | Pentti Veikko Kalevi Hukkanen | FOERFARANDE FOER FRAMSTAELLNING AV ENGAONGSMAOL EXEMPELVIS LERDUVOR FOER SKYTTESPORT ELLER LIKNANDE |
| JP2596994B2 (en) * | 1988-12-06 | 1997-04-02 | 三菱重工業株式会社 | Method for producing hardened gypsum |
| DE729926T1 (en) * | 1995-03-03 | 1997-01-30 | Gyproc Benelux Nv | Process for the production of gypsum components and gypsum components produced by this process |
-
1974
- 1974-08-09 NL NL7410706A patent/NL7410706A/en not_active Application Discontinuation
-
1975
- 1975-08-04 ZA ZA00755010A patent/ZA755010B/en unknown
- 1975-08-06 CA CA232,971A patent/CA1077245A/en not_active Expired
- 1975-08-06 BE BE158959A patent/BE832152A/en not_active IP Right Cessation
- 1975-08-07 IT IT50868/75A patent/IT1041174B/en active
- 1975-08-07 GB GB33057/75A patent/GB1479804A/en not_active Expired
- 1975-08-07 FR FR7524682A patent/FR2281202A1/en active Granted
- 1975-08-08 JP JP50095954A patent/JPS5145120A/ja active Pending
- 1975-08-08 BR BR7505111*A patent/BR7505111A/en unknown
- 1975-08-08 ES ES440142A patent/ES440142A1/en not_active Expired
- 1975-08-08 DE DE19752535577 patent/DE2535577A1/en not_active Withdrawn
- 1975-08-11 PL PL1975182667A patent/PL112807B1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DE2535577A1 (en) | 1976-02-26 |
| NL7410706A (en) | 1976-02-11 |
| BE832152A (en) | 1976-02-06 |
| FR2281202A1 (en) | 1976-03-05 |
| IT1041174B (en) | 1980-01-10 |
| BR7505111A (en) | 1976-08-03 |
| PL112807B1 (en) | 1980-11-29 |
| JPS5145120A (en) | 1976-04-17 |
| GB1479804A (en) | 1977-07-13 |
| FR2281202B1 (en) | 1982-08-20 |
| ZA755010B (en) | 1976-07-28 |
| ES440142A1 (en) | 1977-03-01 |
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