CA1334619C - Process for the preparation of crystalline sodium silicates having a sheet structure - Google Patents
Process for the preparation of crystalline sodium silicates having a sheet structureInfo
- Publication number
- CA1334619C CA1334619C CA000565746A CA565746A CA1334619C CA 1334619 C CA1334619 C CA 1334619C CA 000565746 A CA000565746 A CA 000565746A CA 565746 A CA565746 A CA 565746A CA 1334619 C CA1334619 C CA 1334619C
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- Prior art keywords
- sodium silicate
- spray
- weight
- rotary tubular
- zone
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- 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
- C01B33/20—Silicates
- C01B33/36—Silicates having base-exchange properties but not having molecular sieve properties
- C01B33/38—Layered base-exchange silicates, e.g. clays, micas or alkali metal silicates of kenyaite or magadiite type
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
- Medicines Containing Material From Animals Or Micro-Organisms (AREA)
- Crystals, And After-Treatments Of Crystals (AREA)
- External Artificial Organs (AREA)
Abstract
For the preparation of crystalline sodium silicates hav-ing a sheet structure and an SiO2/Na2O molar ratio of 1.9 : 1 to 3.5 : 1 from waterglass solutions having a solids content of 20 to 65% by weight, the waterglass solutions are first treated in a spray-drying zone. This gives a pulverulent amorphous sodium silicate having a maximum ignition loss of 20% by weight, while the waste gas leaving the spray-drying zone is at a temperature of at least 140°C. Thereafter, the spray-dried sodium silicate is heated in an ignition zone containing an agitated solid bed at temperatures of 500 to 800°C for 1 to 60 minutes in the presence of at least 10% by weight of recycled material. This recycled material was obtained by mechanical comminution of crystalline sodium silicate discharged from the ignition zone.
Description
Process for the preparation of crystalline sodium sili-cates having a sheet structure The present invention relates to a process for the pre-paration of crystalline sodium silicates having a sheet structure and an SiO20/NazO molar ratio of 1.9 : 1 to 3.5 : 1 from waterglass solutions having a solids content of 20 - to 65% by weight.
In the process for the preparation of crystalline sodium silicates according to U.S. Patent 4,585,642, a small amount of crystalline sodium silicate is added to liquid or solid sodium ~isilicate having a water content of 5 to 95%
by weight before water is removed from the reaction mixture and the latter is kept at a temperature of 450C to just below the melting point until the total amount of sodium silicate has crystallized.
Furthermore, U.S. Patent 4,664,839 discloses that, among the vario~s crystal modifications of crystalline sheet silicates of the formula Na25i20s, the S-form has the highest cation exchange power and is therefore particu-larly suitable for softening water.
A disadvantage of the known process is that a solid bulky silicate foam is formed during removal of water from the amorphous sodium silicate. Moreover, during heating of the dehydrated sodlum sillcate, a temperature range of 580 to 630 C is employed, in which, owing to an exotherrnic reaction, the sodium slllcate melts for a short tlme and forms extremely hard, bulky aggregates. In both process steps, there ls therefore the danger that contllluously operatlng apparatuses wlll becorne blocked. Flnally, milllng of the partlcular product, whlch ls requlred ln both process steps, entails considerable expense.
It is therefore the obiect of the present lnventl.on to provlde a process which permits trouble-free contlnuous preparatlon of crysta]line sodium slllcate havlng a sheet structure ln the ~-modlflcatlon from waterglass solutlons wlth llttle mechanlcal comrninutlon.
Accordlngly, the present lnventlon provldes a process for the preparatlon of crystalllne sodlum slllcate havlng a sheet structure and an S102/Na20 rnolar ratlo ranglng from (1.9 to 3.5) sl frorn waterglass solution havlng a sodlum slllcate content of 20 to 65% by weight comprlslng a) spray-drying the waterglass solutlon ln a spray-drylng zone to form an amorphous sodlum sllicate havlng a maximum ignition loss of 20% by welght, exhaust gas leavlng sald spray-drylng zone havlng a temperature of at least 140C.;
b) heating in an anne~ling zone the spray-dried amorphous sodium silicate of step (a) ln a rotary tubular klln incllned 1 to 5 from the horizontal at temperatures ranging from 500 C. to 800 C. for 1 to 60 rnlnutes in order to effect crystalllzatlon of said amorphous sodlum slllcate; and c) recovering sald crystalllne sodlum~sillcate from sald rotary tubular klln;
the lmprovement consistlng essentlally of addlng 10 welght-% to 50 weight-%, based on the weight of sald amorphous sodiutn sillcate, of crystal]ir,e s'odium silicate obtalned by mechanlcal commlnution to the anneallng zone in step b) so as to prevent adherence of any materlal to the walls of sald - rotary tubular klln and thereby enable contlnuous recovery of pulverulent product ln step (C).
It ls also posslble a) for up to 50% by weight of crystalllne sodlum sillcate dlscharged from the lgnitlon zone to be recycled to the ignltion zone after rnechanical comminution;
b) for the mechanically comrnlnuted, crystalline sodium slllcate to have partlcle sizes of 10 to 1,000 ~m;
c) for spray-drying of the waterglass solutions and heatlng of the sodlum silicate to be carried out together in a directly fired rotary tubular kiln;
d) for the waterglass solutlons to ~e sprayed in at the non-fired end of the rotary tubular klln, whlle the heated sodlum slllcate emerges at the flred side of the rotary tubular klln;
e) for the rotary tubular klln to be inclined 1 to 2 to the horlzontal;
f) for the spray-dried sodlurn sillcate to have a maxlmum lgnltlon loss of 5% by welght;
g) for the amount of crystalllne sodlum slllcate recycled to the ignltion zone to be the greater the hlgher the lgnitlon loss of the spray-dried sodium slllcate.
The crystalllne sodlum slllcates obtalned uslng the process accordlng to the lnventlon have pH values of 10.0 to 10.5 and a calclum-blndlng power of more than ~60 meq Ca/100 g (at 20C) or more than 600 meq ca/100 g ~at ~0C) whlle their magneslum-blnding power in the same pH range ls more than 580 meq Mg/lOOg (at 20C) or rnore than 1,000 rneq Mg/lOOg (at 60C).
In the process for the preparation of crystalline sodium silicates according to U.S. Patent 4,585,642, a small amount of crystalline sodium silicate is added to liquid or solid sodium ~isilicate having a water content of 5 to 95%
by weight before water is removed from the reaction mixture and the latter is kept at a temperature of 450C to just below the melting point until the total amount of sodium silicate has crystallized.
Furthermore, U.S. Patent 4,664,839 discloses that, among the vario~s crystal modifications of crystalline sheet silicates of the formula Na25i20s, the S-form has the highest cation exchange power and is therefore particu-larly suitable for softening water.
A disadvantage of the known process is that a solid bulky silicate foam is formed during removal of water from the amorphous sodium silicate. Moreover, during heating of the dehydrated sodlum sillcate, a temperature range of 580 to 630 C is employed, in which, owing to an exotherrnic reaction, the sodium slllcate melts for a short tlme and forms extremely hard, bulky aggregates. In both process steps, there ls therefore the danger that contllluously operatlng apparatuses wlll becorne blocked. Flnally, milllng of the partlcular product, whlch ls requlred ln both process steps, entails considerable expense.
It is therefore the obiect of the present lnventl.on to provlde a process which permits trouble-free contlnuous preparatlon of crysta]line sodium slllcate havlng a sheet structure ln the ~-modlflcatlon from waterglass solutlons wlth llttle mechanlcal comrninutlon.
Accordlngly, the present lnventlon provldes a process for the preparatlon of crystalllne sodlum slllcate havlng a sheet structure and an S102/Na20 rnolar ratlo ranglng from (1.9 to 3.5) sl frorn waterglass solution havlng a sodlum slllcate content of 20 to 65% by weight comprlslng a) spray-drying the waterglass solutlon ln a spray-drylng zone to form an amorphous sodlum sllicate havlng a maximum ignition loss of 20% by welght, exhaust gas leavlng sald spray-drylng zone havlng a temperature of at least 140C.;
b) heating in an anne~ling zone the spray-dried amorphous sodium silicate of step (a) ln a rotary tubular klln incllned 1 to 5 from the horizontal at temperatures ranging from 500 C. to 800 C. for 1 to 60 rnlnutes in order to effect crystalllzatlon of said amorphous sodlum slllcate; and c) recovering sald crystalllne sodlum~sillcate from sald rotary tubular klln;
the lmprovement consistlng essentlally of addlng 10 welght-% to 50 weight-%, based on the weight of sald amorphous sodiutn sillcate, of crystal]ir,e s'odium silicate obtalned by mechanlcal commlnution to the anneallng zone in step b) so as to prevent adherence of any materlal to the walls of sald - rotary tubular klln and thereby enable contlnuous recovery of pulverulent product ln step (C).
It ls also posslble a) for up to 50% by weight of crystalllne sodlum sillcate dlscharged from the lgnitlon zone to be recycled to the ignltion zone after rnechanical comminution;
b) for the mechanically comrnlnuted, crystalline sodium slllcate to have partlcle sizes of 10 to 1,000 ~m;
c) for spray-drying of the waterglass solutions and heatlng of the sodlum silicate to be carried out together in a directly fired rotary tubular kiln;
d) for the waterglass solutlons to ~e sprayed in at the non-fired end of the rotary tubular klln, whlle the heated sodlum slllcate emerges at the flred side of the rotary tubular klln;
e) for the rotary tubular klln to be inclined 1 to 2 to the horlzontal;
f) for the spray-dried sodlurn sillcate to have a maxlmum lgnltlon loss of 5% by welght;
g) for the amount of crystalllne sodlum slllcate recycled to the ignltion zone to be the greater the hlgher the lgnitlon loss of the spray-dried sodium slllcate.
The crystalllne sodlum slllcates obtalned uslng the process accordlng to the lnventlon have pH values of 10.0 to 10.5 and a calclum-blndlng power of more than ~60 meq Ca/100 g (at 20C) or more than 600 meq ca/100 g ~at ~0C) whlle their magneslum-blnding power in the same pH range ls more than 580 meq Mg/lOOg (at 20C) or rnore than 1,000 rneq Mg/lOOg (at 60C).
....
In the process according to the invention, the quality of the resulting amorphous sodium disilicate powder can be influenced ;n a wide range in the course of the spray-S drying by changing the concentration of the waterglasssolution and by controlling the spraying temperature. Thus for example, the amorphous sodium silicate powders to be treated according to the invention in the ignition zone and having a water content of 1 to 20% by weight can be prepared in a hot-air spray tower from waterglass solutions having a modulus (SiO2 : Na20 ratio) of 2.
Advantageously, the process according to the invention can be carried out in a single apparatus which permits the steps comprising spraying of the waterglass solution, heating in an agitated bed and recycling of the crystal-line sodium silicate into the ignition zone. This can be carried out in a fluidized bed reactor or a rotary tubular kiln operated with hot gas, into which waterglass solution is sprayed and into which crystalline sodium silicate is simultaneously metered in. A rotary tubular kiln fired directly with oiL or gas is preferred, in which case the feed and discharge can be arranged at different positions, and, depending on the inclination of the furnace with respect to the horizontal, discharge is effected after a shorter or longer heating time.
In the examples which follow and in which the invention is described in detail, the calcium- and mlagnesium-binding power of the resulting crystal(ine sodium silicates hav-ing a sheet structure are determined as follows:
S Solutions of CaCl2 (corresponding to 300 mg of CaO) or MgCl2 (corresponding to 216 mg of MgO) are added to 1 l of distilled water, with the result that a water having 30 German hardness was obtained.
1 9 of the crystalline sodium silicate obtained in Exam-ples 2 to 7 and O to 6 ml of 1-molar glycine solution ~obtained from 75.1 9 of glycine and 58.4 9 of NaCl which were dissolved in water and made up to 1 l) were added to 1 l of this water, which had been heated to either 20 or 60'oC, and the pH value was then adjusted to 10.4. The suspension was stirred for 30 minutes, during which the pH remained stable. Finally, the solution was filtered and the calcium and magnesium remaining in solu-tion were determined complexometrically in the filtrate.
The calcium- and magnesium-b;nding power were determined by calculating the diference with respect to the original contents.
The results for Examples 2 to 7 are summarized in the attached table.
Example 1 (Comparative Example) , . ..
Amorphous sodium disilicate which had an i~nition loss - 6 - 133~619 of 19% was produced from a waterglass solution having a solids content of 45X and a modulus of 2 in a hot-air spray tower (waste gas temperature: 145C). The amorphous sod;um disilicate was metered into the end wall of a rotary tubular kiln heated electrically from the outside (length: 3 m; diameter: 22 cm; inclination: 1.6) via a metering screw at a rate of 2 kg~h, the residence time in the furnace being about 45 minutes and the tem-perature at its hottest point be;ng 720C.
After the material had initially expanded considerablyin the rotary tubular kiln, it began to adhere to the walls on reaching the zone at about 550C, large leaves being formed, and rolling up to g;ve lumps of about 10 cm diameter. The rotary tubular kiln was blocked by the lumps to such an extent that the material flow in the fur-nace could be maintained only by constant poking. After an operating time of 2 hours, the cross-section of the rotary tubular kiln was virtually completely blocked, so that the experiment had to be discontinued.
Example 2 (Comparative Example) The amorphous sodium disilicate was prepared as in Example 1. The amorphous sodium disilicate was fed via a meter-ing screw into a directly fired rotary tubular kiln (length: 5 m; diameter: 78 cm; inclination: 1.2) at its end opposite the flame, while the crystalline _ 7 _ 1334619 product was discharged at the flame end. 25 kg/h of amor-phous sodium disilicate were metered; the temperature at the hottest point of the rotary tubular kiln was 740C.
s Material adhered to the wall of the rotary tubular kiln and had to be forced off mechanically. AggLomerates formed having a diameter up to about 20 cm.
Example 3 (Comparative Example) The procedure was similar to Example 2; however, 60 kg/h of amorphous sodium disilicate and at the same t;me 5 kg/h of a recycled material obta;ned by comm;nut;ng the product obta;ned ;n Example 2 to less than 250 ~m were metered.
Material adhered only weakly to the wall of the rotary tubular k;ln and could be removed by occas;onal tapping.
The largest agglomerates occuring had a diameter of about 8 cm.
Example 4 (according to the invention) Example 3 was repeated with the modificat;on that 15 kg/h of recyc(ed mater;al were metered.
No mater;al adhered to the wall of the rotary tubular kiln the crytall;ne sodium silicate discharged was substan-t;ally pulverulent. `
-Example 5 (according to the invention) A waterglass solution hav;ng a solids content of 55% and a modulus of 2 was spray-dried in a hot-air spray tower, the waste gas temperature being 230C and an amorphous sodium disilicate having an ignition loss of 4.7% being obtained.
The amorphous sodium disilicate was metered at a rate of 40 kg/h, together with 4 kg/h of recycled material, into a gas-fired rotary tubular kiln (inclination: 1.2).
No caking occurred in the rotary tubular kiln; the dis-charged crystalline sodium silicate was substantially pulverulent.
Example 6 (according to the invention) The waterglass solution according to Example 5 was sprayed through the flame of a directly fired spray tower. An amor-phous sodium disilicate having an ignition loss of 1.4X
was obtained at a waste gas temperature of 450C. The amorphous sodium disilicate was heated together with the recycled material, as stated in Example 5. In this case too, no caking occurred in the rotary tubular kiln and a substantially pulverulent sodium silicate resulted.
Example 7 (according to the invention) The rotary tubular kiln described in Example 2 was addi-tionally equipped, on its product-inlet s;de, with a spray system through wh;ch 50 l/h of a 50% strength waterglass solution were sprayed. At the same t;me, 5 kg/h of re-cycled material were introduced via a sol;ds meter;ng system, cocurrently w;th the sprayed waterglass solut;on~.
The waste gas temperature was 220C and the temperature ' .. 't,: ~ 10 at the hottest po;nt of the rotary tubular kiln was 750C.
The pr;mary spray product had an ignition loss of 4.8Z.
No material adhered to the wall of the rotary tubular kiln.
The largest agglomerates ;n the d;scharged crystall;ne sod;um had a d;ameter of about 3 cm.
Table Calcium- and magnesium-binding pouer of crystaLline sodium silicates having a sheet structure at pH 10.4 According to Example Calcium-binding power CmgCa~g~ Magnesium-binding power [mgMg/g~
at 20~ at 60 C at 20C at 60C
3 72 120 70 t24
In the process according to the invention, the quality of the resulting amorphous sodium disilicate powder can be influenced ;n a wide range in the course of the spray-S drying by changing the concentration of the waterglasssolution and by controlling the spraying temperature. Thus for example, the amorphous sodium silicate powders to be treated according to the invention in the ignition zone and having a water content of 1 to 20% by weight can be prepared in a hot-air spray tower from waterglass solutions having a modulus (SiO2 : Na20 ratio) of 2.
Advantageously, the process according to the invention can be carried out in a single apparatus which permits the steps comprising spraying of the waterglass solution, heating in an agitated bed and recycling of the crystal-line sodium silicate into the ignition zone. This can be carried out in a fluidized bed reactor or a rotary tubular kiln operated with hot gas, into which waterglass solution is sprayed and into which crystalline sodium silicate is simultaneously metered in. A rotary tubular kiln fired directly with oiL or gas is preferred, in which case the feed and discharge can be arranged at different positions, and, depending on the inclination of the furnace with respect to the horizontal, discharge is effected after a shorter or longer heating time.
In the examples which follow and in which the invention is described in detail, the calcium- and mlagnesium-binding power of the resulting crystal(ine sodium silicates hav-ing a sheet structure are determined as follows:
S Solutions of CaCl2 (corresponding to 300 mg of CaO) or MgCl2 (corresponding to 216 mg of MgO) are added to 1 l of distilled water, with the result that a water having 30 German hardness was obtained.
1 9 of the crystalline sodium silicate obtained in Exam-ples 2 to 7 and O to 6 ml of 1-molar glycine solution ~obtained from 75.1 9 of glycine and 58.4 9 of NaCl which were dissolved in water and made up to 1 l) were added to 1 l of this water, which had been heated to either 20 or 60'oC, and the pH value was then adjusted to 10.4. The suspension was stirred for 30 minutes, during which the pH remained stable. Finally, the solution was filtered and the calcium and magnesium remaining in solu-tion were determined complexometrically in the filtrate.
The calcium- and magnesium-b;nding power were determined by calculating the diference with respect to the original contents.
The results for Examples 2 to 7 are summarized in the attached table.
Example 1 (Comparative Example) , . ..
Amorphous sodium disilicate which had an i~nition loss - 6 - 133~619 of 19% was produced from a waterglass solution having a solids content of 45X and a modulus of 2 in a hot-air spray tower (waste gas temperature: 145C). The amorphous sod;um disilicate was metered into the end wall of a rotary tubular kiln heated electrically from the outside (length: 3 m; diameter: 22 cm; inclination: 1.6) via a metering screw at a rate of 2 kg~h, the residence time in the furnace being about 45 minutes and the tem-perature at its hottest point be;ng 720C.
After the material had initially expanded considerablyin the rotary tubular kiln, it began to adhere to the walls on reaching the zone at about 550C, large leaves being formed, and rolling up to g;ve lumps of about 10 cm diameter. The rotary tubular kiln was blocked by the lumps to such an extent that the material flow in the fur-nace could be maintained only by constant poking. After an operating time of 2 hours, the cross-section of the rotary tubular kiln was virtually completely blocked, so that the experiment had to be discontinued.
Example 2 (Comparative Example) The amorphous sodium disilicate was prepared as in Example 1. The amorphous sodium disilicate was fed via a meter-ing screw into a directly fired rotary tubular kiln (length: 5 m; diameter: 78 cm; inclination: 1.2) at its end opposite the flame, while the crystalline _ 7 _ 1334619 product was discharged at the flame end. 25 kg/h of amor-phous sodium disilicate were metered; the temperature at the hottest point of the rotary tubular kiln was 740C.
s Material adhered to the wall of the rotary tubular kiln and had to be forced off mechanically. AggLomerates formed having a diameter up to about 20 cm.
Example 3 (Comparative Example) The procedure was similar to Example 2; however, 60 kg/h of amorphous sodium disilicate and at the same t;me 5 kg/h of a recycled material obta;ned by comm;nut;ng the product obta;ned ;n Example 2 to less than 250 ~m were metered.
Material adhered only weakly to the wall of the rotary tubular k;ln and could be removed by occas;onal tapping.
The largest agglomerates occuring had a diameter of about 8 cm.
Example 4 (according to the invention) Example 3 was repeated with the modificat;on that 15 kg/h of recyc(ed mater;al were metered.
No mater;al adhered to the wall of the rotary tubular kiln the crytall;ne sodium silicate discharged was substan-t;ally pulverulent. `
-Example 5 (according to the invention) A waterglass solution hav;ng a solids content of 55% and a modulus of 2 was spray-dried in a hot-air spray tower, the waste gas temperature being 230C and an amorphous sodium disilicate having an ignition loss of 4.7% being obtained.
The amorphous sodium disilicate was metered at a rate of 40 kg/h, together with 4 kg/h of recycled material, into a gas-fired rotary tubular kiln (inclination: 1.2).
No caking occurred in the rotary tubular kiln; the dis-charged crystalline sodium silicate was substantially pulverulent.
Example 6 (according to the invention) The waterglass solution according to Example 5 was sprayed through the flame of a directly fired spray tower. An amor-phous sodium disilicate having an ignition loss of 1.4X
was obtained at a waste gas temperature of 450C. The amorphous sodium disilicate was heated together with the recycled material, as stated in Example 5. In this case too, no caking occurred in the rotary tubular kiln and a substantially pulverulent sodium silicate resulted.
Example 7 (according to the invention) The rotary tubular kiln described in Example 2 was addi-tionally equipped, on its product-inlet s;de, with a spray system through wh;ch 50 l/h of a 50% strength waterglass solution were sprayed. At the same t;me, 5 kg/h of re-cycled material were introduced via a sol;ds meter;ng system, cocurrently w;th the sprayed waterglass solut;on~.
The waste gas temperature was 220C and the temperature ' .. 't,: ~ 10 at the hottest po;nt of the rotary tubular kiln was 750C.
The pr;mary spray product had an ignition loss of 4.8Z.
No material adhered to the wall of the rotary tubular kiln.
The largest agglomerates ;n the d;scharged crystall;ne sod;um had a d;ameter of about 3 cm.
Table Calcium- and magnesium-binding pouer of crystaLline sodium silicates having a sheet structure at pH 10.4 According to Example Calcium-binding power CmgCa~g~ Magnesium-binding power [mgMg/g~
at 20~ at 60 C at 20C at 60C
3 72 120 70 t24
Claims (8)
1. In a process for the preparation of crystalline sodium silicate having a sheet structure and an SiO2/Na2O molar ratio ranging from (1.9 to 3.5):1 from waterglass solution having a sodium silicate content of 20 to 65% by weight comprising a) spray-drying the waterglass solution in a spray-drying zone to form an amorphous sodium silicate having a maximum ignition loss of 20% by weight, exhaust gas leaving said spray-drying zone having a temperature of at least 140°C.;
b) heating in an annealing zone the spray-dried amorphous sodium silicate of step (a) in a rotary tubular kiln inclined 1° to 5° from the horizontal at temperatures ranging from 500°C. to 800°C. for 1 to 60 minutes in order to effect crystallization of said amorphous sodium silicate; and c) recovering said crystalline sodium silicate from said rotary tubular kiln;
the improvement consisting essentially of adding 10 weight-% to 50 weight-%, based on the weight of said amorphous sodium silicate, of crystalline sodium silicate obtained by mechanical comminution to the annealing zone in step b) so as to prevent adherence of any material to the walls of said rotary tubular kiln and thereby enable continuous recovery of pulverulent product in step (C).
b) heating in an annealing zone the spray-dried amorphous sodium silicate of step (a) in a rotary tubular kiln inclined 1° to 5° from the horizontal at temperatures ranging from 500°C. to 800°C. for 1 to 60 minutes in order to effect crystallization of said amorphous sodium silicate; and c) recovering said crystalline sodium silicate from said rotary tubular kiln;
the improvement consisting essentially of adding 10 weight-% to 50 weight-%, based on the weight of said amorphous sodium silicate, of crystalline sodium silicate obtained by mechanical comminution to the annealing zone in step b) so as to prevent adherence of any material to the walls of said rotary tubular kiln and thereby enable continuous recovery of pulverulent product in step (C).
2. A process as claimed in claim 1, wherein up to 50% by weight of crystalline sodium silicate discharged from the ignition zone is recycled to the ignition zone after mechanical communition.
3. A process as claimed in claim 1, wherein the mechanically comminuted, crystalline sodium silicate has particle sizes of 10 to 1,000 µm.
4. A process as claimed in claim 1, wherein the spray-drying of the waterglass solutions and the heating of the sodium silicate are carried out together in a directly fired rotary tubular kiln.
5. A process as claimed in claim 4, wherein the waterglass solutions are sprayed in at the non-fired end of the rotary tubular kiln while the heated sodium silicate emerges at the fired side of the rotary tubular kiln.
6. A process as claimed in claim 1, wherein the rotary tubular kiln is inclined 1 to 2° to the horizontal.
7. A process as claimed in claim 1, wherein the spray-dried sodium silicate has a maximum ignition loss of 5% by weight.
8. A process as claimed in claim 1, wherein the amount of crystalline sodium silicate recycled to the ignition zone is greater the higher the ignition loss of the spray-dried sodium silicate.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3718350.8 | 1987-06-01 | ||
| DE19873718350 DE3718350A1 (en) | 1987-06-01 | 1987-06-01 | METHOD FOR PRODUCING CRYSTALLINE SODIUM SILICATES WITH LAYER STRUCTURE |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1334619C true CA1334619C (en) | 1995-03-07 |
Family
ID=6328822
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000565746A Expired - Fee Related CA1334619C (en) | 1987-06-01 | 1988-05-03 | Process for the preparation of crystalline sodium silicates having a sheet structure |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0293640B1 (en) |
| JP (1) | JPS63310717A (en) |
| AT (1) | ATE73737T1 (en) |
| CA (1) | CA1334619C (en) |
| DE (2) | DE3718350A1 (en) |
| DK (1) | DK167917B1 (en) |
| ES (1) | ES2031175T3 (en) |
| NO (1) | NO171671C (en) |
| PT (1) | PT87624B (en) |
Families Citing this family (22)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5229095A (en) * | 1989-10-25 | 1993-07-20 | Hoechst Aktiengesellschaft | Process for producing amorphous sodium silicate |
| CA2025073C (en) * | 1989-10-25 | 1995-07-18 | Gunther Schimmel | Process for producing sodium silicates |
| CA2024966C (en) | 1989-10-25 | 1995-07-18 | Gunther Schimmel | Process for producing sodium silicates |
| US5236682A (en) * | 1989-10-25 | 1993-08-17 | Hoechst Aktiengesellschaft | Process for producing crystalline sodium silicates having a layered structure |
| DE4000705A1 (en) * | 1990-01-12 | 1991-07-18 | Hoechst Ag | METHOD FOR PRODUCING CRYSTALLINE SODIUM SILICATES |
| DE4102743A1 (en) * | 1991-01-30 | 1992-08-06 | Henkel Kgaa | PHOSPHATE-FREE DETERGENT |
| DE4107230C2 (en) * | 1991-03-07 | 1995-04-06 | Hoechst Ag | Process for the production of sodium silicates |
| DE4107231A1 (en) * | 1991-03-07 | 1992-09-10 | Hoechst Ag | METHOD FOR PRODUCING SODIUM SILICATE |
| DE4142711A1 (en) * | 1991-12-21 | 1993-06-24 | Hoechst Ag | METHOD FOR PRODUCING CRYSTALLINE SODIUM DISILICATES |
| US5567404A (en) * | 1994-05-31 | 1996-10-22 | Korea Research Institute Of Chemical Technology | Process for preparation of layered sodium silicate from anhydrous sodium silicate |
| KR0139976B1 (en) * | 1994-05-31 | 1998-06-01 | 강박광 | Process for preparing crystalline sodium silicates having a laminated structure |
| DE4419744A1 (en) * | 1994-06-06 | 1995-12-07 | Henkel Kgaa | Pressure-free low-temperature synthesis of crystalline disilicate |
| US5614160A (en) * | 1994-06-10 | 1997-03-25 | Pq Corporation | Composite silicate materials |
| DE4421851A1 (en) * | 1994-06-22 | 1996-01-04 | Henkel Kgaa | Process for the low-temperature synthesis of crystalline Disilicate-II |
| DE4421850A1 (en) * | 1994-06-22 | 1996-01-04 | Henkel Kgaa | Process for the low-temperature synthesis of crystalline Disilicate-I |
| DE19707448C2 (en) * | 1997-02-25 | 1998-11-26 | Clariant Gmbh | Process for the production of crystalline sodium silicates |
| DE19707449C1 (en) * | 1997-02-25 | 1998-04-09 | Clariant Gmbh | Layered sodium silicate preparation with high delta-phase content |
| KR100280376B1 (en) * | 1998-08-14 | 2001-02-01 | 김충섭 | Method for preparing crystalline layered sodium disilicate |
| CN100340484C (en) * | 2005-09-01 | 2007-10-03 | 成都长江通信有限公司 | Crystallized sodium disilicate preparation method |
| JP2010512447A (en) | 2006-12-11 | 2010-04-22 | ザ プロクター アンド ギャンブル カンパニー | Improved visual perception of images on printed film |
| US20080210265A1 (en) | 2007-03-01 | 2008-09-04 | Crawford Charles A | Coating removal composition |
| EP2028261B1 (en) | 2007-08-16 | 2013-01-16 | The Procter & Gamble Company | Process For Making A Detergent Composition |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3875282A (en) * | 1973-04-30 | 1975-04-01 | Stauffer Chemical Co | Production of high bulk density spray dried hydrous sodium silicate |
| JPS6056484B2 (en) * | 1977-07-20 | 1985-12-10 | 株式会社日立製作所 | Vacuum cleaner dust removal device |
| DE3413571A1 (en) * | 1984-04-11 | 1985-10-24 | Hoechst Ag, 6230 Frankfurt | USE OF CRYSTALLINE LAYERED SODIUM SILICATES FOR WATER SOFTENING AND METHOD FOR WATER SOFTENING |
| DE3417649A1 (en) * | 1984-05-12 | 1985-11-14 | Hoechst Ag, 6230 Frankfurt | METHOD FOR PRODUCING CRYSTALLINE SODIUM SILICATES |
-
1987
- 1987-06-01 DE DE19873718350 patent/DE3718350A1/en not_active Withdrawn
-
1988
- 1988-05-03 CA CA000565746A patent/CA1334619C/en not_active Expired - Fee Related
- 1988-05-09 AT AT88107429T patent/ATE73737T1/en not_active IP Right Cessation
- 1988-05-09 DE DE8888107429T patent/DE3869209D1/en not_active Expired - Fee Related
- 1988-05-09 EP EP88107429A patent/EP0293640B1/en not_active Expired - Lifetime
- 1988-05-09 ES ES198888107429T patent/ES2031175T3/en not_active Expired - Lifetime
- 1988-05-30 JP JP63130498A patent/JPS63310717A/en active Granted
- 1988-05-31 PT PT87624A patent/PT87624B/en not_active IP Right Cessation
- 1988-05-31 DK DK295488A patent/DK167917B1/en not_active IP Right Cessation
- 1988-05-31 NO NO882391A patent/NO171671C/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| DK295488D0 (en) | 1988-05-31 |
| JPH0566888B2 (en) | 1993-09-22 |
| ES2031175T3 (en) | 1992-12-01 |
| EP0293640A2 (en) | 1988-12-07 |
| NO882391L (en) | 1988-12-02 |
| NO171671B (en) | 1993-01-11 |
| EP0293640A3 (en) | 1989-11-29 |
| DK295488A (en) | 1988-12-02 |
| NO882391D0 (en) | 1988-05-31 |
| PT87624B (en) | 1992-09-30 |
| EP0293640B1 (en) | 1992-03-18 |
| NO171671C (en) | 1993-04-28 |
| DE3869209T (en) | 1992-04-23 |
| DE3718350A1 (en) | 1988-12-22 |
| ATE73737T1 (en) | 1992-04-15 |
| DE3869209D1 (en) | 1992-04-23 |
| JPS63310717A (en) | 1988-12-19 |
| PT87624A (en) | 1988-06-01 |
| DK167917B1 (en) | 1994-01-03 |
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