CA2025073C - Process for producing sodium silicates - Google Patents
Process for producing sodium silicatesInfo
- Publication number
- CA2025073C CA2025073C CA002025073A CA2025073A CA2025073C CA 2025073 C CA2025073 C CA 2025073C CA 002025073 A CA002025073 A CA 002025073A CA 2025073 A CA2025073 A CA 2025073A CA 2025073 C CA2025073 C CA 2025073C
- Authority
- CA
- Canada
- Prior art keywords
- rotary kiln
- sodium silicate
- weight
- water content
- amorphous sodium
- 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 - Fee Related
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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
- C01B33/20—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
-
- 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
- C01B33/32—Alkali metal silicates
-
- 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
- C01B33/32—Alkali metal silicates
- C01B33/325—After-treatment, e.g. purification or stabilisation of solutions, granulation; Dissolution; Obtaining solid silicate, e.g. from a solution by spray-drying, flashing off water or adding a coagulant
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
Abstract
For producing amorphous sodium silicates having a water content of 0.3 to 6% by weight and an SiO2/Na2O molar ratio of (1.9 to 2.8) : 1 from a waterglass solution containing at least 20% by weight of solids, the water-glass solution is obtained by reacting quartz sand with sodium hydroxide solution at an SiO2/Na2O molar ratio of (2.0 to 2.8) : 1 at temperatures of 180 to 240°C and pressures of 10 to 30 bar. This waterglass solution is treated in a spray-drying zone with hot air at 200 to 300°C for a residence time of 10 to 20 seconds and at a temperature of the exit gas leaving the spray-drying zone of 90 to 130°C, to form a pulverulent amorphous sodium silicate having a water content (determined as the loss on ignition at 700°C) of 15 to 23% by weight and a bulk density of more than 300 g/l. The pulverulent sodium silicate is introduced into an obliquely arranged rotary kiln fitted with devices for moving solids and treated therein with flue gas in countercurrent at temperatures from 250 up to 500°C for 1 to 60 minutes. The rotary kiln is here insulated in such a way that its outside wall temperature is less than 60°C. Finally, the amorphous sodium silicate emerging from the rotary kiln is com-minuted by means of a mechanical crusher to grain sizes of 0.1 to 12 mm.
Description
~ 202507~
The present invention relates to a process for producing amorphous sodium silicates having a water content of 0.3 to 6 percent by weight, preferably of 0.5 to 2 percent by weight, and an SiO2/Na2O molar ratio of (1.9 to 2.8) : 1 from a waterglass solution contA;ning at least 20 percent by weight of solids.
From US Patent 3,471,253, it is known to obtain a water-glass solution by introducing 42 percent by weight sodium hydroxide solution and sand (silica) in a weight ratio of about 2 : 1 into a stirred autoclave and allowing the mixture to remain therein for 3 hours at 210C and 16 bar. The hot sodium silicate solution taken out after cooling of the autoclave content to 85C contains, after excess sand and other impurities have been filtered off, 57.5% of solids and has an SiO2/Na2O ratio of 1.64 : 1.
Crystalline sodium silicates having a layer structure and an SiOz/Na2O molar ratio of (1.9 to 3.5) : 1 are produced by the process according to German Offenlegungsschrift 3,718,350 by treating waterglass solutions having a solids content of 20 to 65 percent by weight in a spray-drying zone to form a water-contAining amorphous sodium silicate, the exit gas flowing out of the spray-drying zone having a temperature of at least 140C. The water-cont~;ning amorphous sodium silicate is heat-treated in an ignition zone for 1 to 60 minutes at 500 to 800C in the presence of at least 10 percent by weight of recycle material, which was obtained by mechanical comm;nlltion of crys~All;ne sodium silicate previously discharged from the ignition zone.
A disadvantage in the lastmentioned process is that the material obtained in spray-drying takes up a large volume because of its low bulk density of 100 to 250 g/l and generates a lot of dust. Moreover, the use of recycle material during the heat treatment causes considerably greater expense on equipment and, because of the higher ''~;~
` .
throughput of material, requires a rotary tube of greater ~;mensions.
According to the invention, the said disadvantages in the production of amorphous sodium silicates from a water-glass solution contA;n;ng at least 20% by weight of solids are overcome by a) obt~in;ng the waterglass solution by reacting quartz sand with sodium hydroxide solution in an SiO2/Na20 molar ratio of (2.0 to 2.8) : 1 at temperatures from 180 to 240C and pressures from 10 to 30 bar, b) treating the waterglass solution in a spray-drying zone with hot air at 200 to 300C for a residence time of 10 to 25 seconds and at a temperature of the exit gas leaving the spray-drying zone of 90 to 130C, to form a pulverulent amorphous sodium silicate having a water content (det~rm;ned as the loss on ignition at 700C) of 15 to 23% by weight and a bulk density of more than 300 g/l, c) introducing the pulverulent sodium silicate accord-ing to b) into an obliquely arranged rotary kiln fitted with devices for moving solids and treating it therein with flue gas in counter-current at temperatures from 250 up to 500C for 1 to 60 minutes, the rotary kiln being insulated in such a way that its outside wall temperature is less than 60C, and d) comminuting the amorphous sodium silicate emerging from the rotary kiln by means of a mechAn;c~
crusher to grain sizes of 0.1 to 12 mm.
Furthermore, the process according to the invention can, if desired, also be further developed by aa) grinding the co~~;nllted sodium silicate by means of a mill to grain sizes of 2 to 400 ~m;
bb) using a mechanical mill running at a circumferential speed of 0.5 to 60 m/second;
.... _~
202~073 ` , cc) using an air jet mill;
dd) using a ceramically lined ball mill;
ee) using a ceramically lined vibratory mill;
ff) extracting the exit gas from the rotary kiln in the central region thereof and in the region of the end where the pulverulent amorphous sodium silicate having a water content of 15 to 23% by weight is introduced, and purifying the exit gas by means of a dry dust filter, the sodium silicate taken from the dry dust filter being quasi-continuously admixed to the pulverulent amorphous sodium silicate des-tined to be introduced into the rotary kiln;
gg) feeding the ground sodium silicate to a roll compac-tor, by means of which it is compressed at a roll-pressing force of 20 to 40 kN/cm of roll width to give compact pieces;
hh) processing the compact pieces, after pre-comminution by forcing them through screens, to give granules having a bulk density of 700 to 1000 g/l.
Sodium silicates can be used as water-softening agents.
In the process according to the invention, a sodium silicate of high bulk density which can readily be handled, is obtained owing to the low temperature and the short residence time in the spraying of the waterglass solution.
Due to the low heat transfer through the wall of the rotary kiln because of its good insulation, the ten~ency of the sodium silicate to stick is counteracted in the process according to the invention.
In the process according to the invention, the use of a 2025~7~
_ - 4 -low-speed mechanical mill tfor example a disk mill, beater mill, hammer mill or roll mill) is necessary in order to avoid abrasion of iron from the grinding tools.
If a ceramically lined ball mill or a vibratory mill or an air jet mill for very fine products, i.e. those having diameters of 6 to 10 ~m is used in the process according to the invention, likewise no contAm;n~tion of the sodium silicate due to metal abrasion occurs.
In the process according to the invention, the dust loading in the exit gas is considerably reduced by the simultaneous extraction of dust-cont~;n;ng exit gas in the central region of the rotary tube and in the region of its charging end, ~ecause dust is released above all during charging of the sodium silicate to the rotary kiln and because the gas velocity is reduced in the region where the amorphous, water-cont~;n;ng sodium silicate is charged.
Using the process according to the invention, an abrasion-resistant granulated product, which very quickly disintegrates in water, is obtained by compacting.
The residual hardnesses indicated in Examples 2 and 3 were det~rm;ned by the following procedure:
The present invention relates to a process for producing amorphous sodium silicates having a water content of 0.3 to 6 percent by weight, preferably of 0.5 to 2 percent by weight, and an SiO2/Na2O molar ratio of (1.9 to 2.8) : 1 from a waterglass solution contA;ning at least 20 percent by weight of solids.
From US Patent 3,471,253, it is known to obtain a water-glass solution by introducing 42 percent by weight sodium hydroxide solution and sand (silica) in a weight ratio of about 2 : 1 into a stirred autoclave and allowing the mixture to remain therein for 3 hours at 210C and 16 bar. The hot sodium silicate solution taken out after cooling of the autoclave content to 85C contains, after excess sand and other impurities have been filtered off, 57.5% of solids and has an SiO2/Na2O ratio of 1.64 : 1.
Crystalline sodium silicates having a layer structure and an SiOz/Na2O molar ratio of (1.9 to 3.5) : 1 are produced by the process according to German Offenlegungsschrift 3,718,350 by treating waterglass solutions having a solids content of 20 to 65 percent by weight in a spray-drying zone to form a water-contAining amorphous sodium silicate, the exit gas flowing out of the spray-drying zone having a temperature of at least 140C. The water-cont~;ning amorphous sodium silicate is heat-treated in an ignition zone for 1 to 60 minutes at 500 to 800C in the presence of at least 10 percent by weight of recycle material, which was obtained by mechanical comm;nlltion of crys~All;ne sodium silicate previously discharged from the ignition zone.
A disadvantage in the lastmentioned process is that the material obtained in spray-drying takes up a large volume because of its low bulk density of 100 to 250 g/l and generates a lot of dust. Moreover, the use of recycle material during the heat treatment causes considerably greater expense on equipment and, because of the higher ''~;~
` .
throughput of material, requires a rotary tube of greater ~;mensions.
According to the invention, the said disadvantages in the production of amorphous sodium silicates from a water-glass solution contA;n;ng at least 20% by weight of solids are overcome by a) obt~in;ng the waterglass solution by reacting quartz sand with sodium hydroxide solution in an SiO2/Na20 molar ratio of (2.0 to 2.8) : 1 at temperatures from 180 to 240C and pressures from 10 to 30 bar, b) treating the waterglass solution in a spray-drying zone with hot air at 200 to 300C for a residence time of 10 to 25 seconds and at a temperature of the exit gas leaving the spray-drying zone of 90 to 130C, to form a pulverulent amorphous sodium silicate having a water content (det~rm;ned as the loss on ignition at 700C) of 15 to 23% by weight and a bulk density of more than 300 g/l, c) introducing the pulverulent sodium silicate accord-ing to b) into an obliquely arranged rotary kiln fitted with devices for moving solids and treating it therein with flue gas in counter-current at temperatures from 250 up to 500C for 1 to 60 minutes, the rotary kiln being insulated in such a way that its outside wall temperature is less than 60C, and d) comminuting the amorphous sodium silicate emerging from the rotary kiln by means of a mechAn;c~
crusher to grain sizes of 0.1 to 12 mm.
Furthermore, the process according to the invention can, if desired, also be further developed by aa) grinding the co~~;nllted sodium silicate by means of a mill to grain sizes of 2 to 400 ~m;
bb) using a mechanical mill running at a circumferential speed of 0.5 to 60 m/second;
.... _~
202~073 ` , cc) using an air jet mill;
dd) using a ceramically lined ball mill;
ee) using a ceramically lined vibratory mill;
ff) extracting the exit gas from the rotary kiln in the central region thereof and in the region of the end where the pulverulent amorphous sodium silicate having a water content of 15 to 23% by weight is introduced, and purifying the exit gas by means of a dry dust filter, the sodium silicate taken from the dry dust filter being quasi-continuously admixed to the pulverulent amorphous sodium silicate des-tined to be introduced into the rotary kiln;
gg) feeding the ground sodium silicate to a roll compac-tor, by means of which it is compressed at a roll-pressing force of 20 to 40 kN/cm of roll width to give compact pieces;
hh) processing the compact pieces, after pre-comminution by forcing them through screens, to give granules having a bulk density of 700 to 1000 g/l.
Sodium silicates can be used as water-softening agents.
In the process according to the invention, a sodium silicate of high bulk density which can readily be handled, is obtained owing to the low temperature and the short residence time in the spraying of the waterglass solution.
Due to the low heat transfer through the wall of the rotary kiln because of its good insulation, the ten~ency of the sodium silicate to stick is counteracted in the process according to the invention.
In the process according to the invention, the use of a 2025~7~
_ - 4 -low-speed mechanical mill tfor example a disk mill, beater mill, hammer mill or roll mill) is necessary in order to avoid abrasion of iron from the grinding tools.
If a ceramically lined ball mill or a vibratory mill or an air jet mill for very fine products, i.e. those having diameters of 6 to 10 ~m is used in the process according to the invention, likewise no contAm;n~tion of the sodium silicate due to metal abrasion occurs.
In the process according to the invention, the dust loading in the exit gas is considerably reduced by the simultaneous extraction of dust-cont~;n;ng exit gas in the central region of the rotary tube and in the region of its charging end, ~ecause dust is released above all during charging of the sodium silicate to the rotary kiln and because the gas velocity is reduced in the region where the amorphous, water-cont~;n;ng sodium silicate is charged.
Using the process according to the invention, an abrasion-resistant granulated product, which very quickly disintegrates in water, is obtained by compacting.
The residual hardnesses indicated in Examples 2 and 3 were det~rm;ned by the following procedure:
2.5 g of sodium silicate were suspended in 1000 ml of tap water of 18 German hardness (corresponds to a content of 85 mg of Ca and 15 mg of Mg per liter). The suspension was stirred for 30 minutes at 60C by means of a magnet stirrer at about 500 rpm. After rapid cooling in ice water to 20C, the suspension was filtered through a membrane filter (pore width: 0.45 ~m). The calcium and magnesium contents in the clear filtrate were determined by means of atomic absorption.
202~07~
Example 1 (according to the state of the art) In a hot-air spray tower (exit gas temperature: 145C), amorphous sodium disilicate having a 1088 on ignition of 19~ at 700C and a bulk density of 220 g/l was produced rom a waterglass solution having a solids content of 45%.
60 kg/hour of amorphous sodium disilicate having a water content (determined as the 1088 on ignition at 700C) of 18% by weight and 15 kg/h of a recycle material, which had been obtained by comminution of a product, obtained in a previous batch, to less than 250 ~m, were charged via a metering screw to a directly fired rotary kiln (length: 5 m; diameter: 78 cm; inclination: 1.2) at its end opposite the flame, while the crystalline product was discharged from the flame side. The temperature at the hottest point in the rotary kiln was 740C.
No material sticking to the wall of the rotary kiln was formed; the discharged sodium disilicate was largely pulverulent.
~Ample 2 (according to the invention) Sand (99 percent by weight of SiO2; grain size 90%
< 0.5 mm) and 50 percent by weight sodium hydroxide solu-tion in an SiO2/Na2O molar ratio of 2.15 : 1 were filled into a nickel-lined cylindrical autoclave fitted with a stirrer device. With the autoclave being stirred, the mixture was heated to 200C by injecting steam (16 bar) and held for 60 minutes at this temperatùre. The content of the autoclave was then let down through a flash vessel into a tank and, after the addition of 0.3% by weight of perlite as a filter aid, filtered at 90C through a disk pressure filter to separate off the insoluble matter. As the filtrate, a clear waterglass solution having an SiO2/Na2O molar ratio of 2.04 : 1 was obtained. The solids content was adjusted to 50% by dilution with water.
2~ 73 ~ - 6 -The waterglass solution was sprayed in a hot-air spray tower which was fitted with a disk atomizer and which was heated via a gas-fired combustion chamber and connected to a pneumatically cleaning hose filter for precipitating the product, the combustion chamber having been adjusted in such a way that the hot gas entering at the tower top had a temperature of 260C. The rate of the waterglass solution to be sprayed was adjusted such that the tem-perature of the silicate/gas mixture leaving the spray tower was 105C. The residence time was calculated to be 16 seconds from the volume of the spray tower and the gas throughput through the spray tower. The amorphous sodium disilicate precipitated on the hose filter had, at a low dusting te~ency, a bulk density of 480 g/l, an iron content of 0.01~ by weight, an SiO2/Na2O ratio of 2.04:1 and a water content (deterrined as the loss on ignition at 700C) of 19.4%; its mean particle diameter was 52 ~m.
The rotary kiln described in Example 1 had been insulated by several plies of mineral wool and a sheet metal jacket in such a way that, at a temperature of 390C in the interior of the rotary kiln, a ~-~imllm temperature of 38C occurred on its outer skin. 60 kg of the amorphous sodium disilicate were introduced per hour into this rotary kiln, no sticky material being formed. The amor-phous sodium disilicate (Na2Si2O5) leaving the rotary kiln and showing a water content of 0.7% by weight (determined as the loss on ignition at 700C) was comminuted by means of a mechanical crusher to a grain size of less than 6 mm and, after interm~Ai~te cooling, ground on a disk mill (diameter: 30 cm) at 400 min~1 to a mean particle diameter of 95 ~m, the iron content of the ground product being identical to that of the sodium disilicate introduced into the rotary kiln.
The exit gas from the rotary kiln was extracted in the region where the amorphous sodium disilicate having a water content (det~rmin~A as the loss on ignition at 700C) of 19.4% by weight was introduced, and fed to a scrubbing tower. 3 kg of sodium disilicate per hour were discharged with the exit gas.
The residual hardness of the sodium disilicate thus produced was 2.5 mg/l of Ca and less than 1 mg/l of Mg.
Example 3 (according to the invention) Example 2 was repeated with the modification that the temperature was 300C in the interior of the rotary kiln and 35C on its outer skin. The amorphous sodium disili-cate leaving the rotary kiln here had a water content (determined as the loss on ignition at 700C) of 5% by weight. The residual hardness of the sodium disilicate produced in this way was 3.5 mg/l of Ca and 1.5 mg/l of Mg.
Example 4 (according to the invention) The product obtained according to Example 2 having a mean particle diameter of 95 ~m was further comminuted by m~nS of a fluid-bed opposed jet mill with an integrated mechanical classifier device. Depending on the set speed of rotation of the classifier, an attrition-free sodium disilicate having a mean particle diameter of 2 to 15 ~m was obtained.
Example 5 (according to the invention) The product obtained according to Example 2 was further comminuted by means of a porcelain-lined ball mill filled with corlln~um balls. An attrition-free sodium disilicate having a mean particle diameter of 5 to 14 ~m, depending on the grinding time, was obtained.
ple 6 (according to the invention) The product obtained according to Example 2 was processed in a roll compactor having a pressing force of the . . _ . . _ _ = . _ .
compacting rolls of 30 kN/cm of roll width with subse-quent comminlltion of the flakes in a screen granulator to give dust-free granules having a mean particle diameter of 900 ~m, a bulk density of 870 g/l and a high abrasion resistance.
For the determ;n~tion of the abrasion resis-tance, 50 g of granules are treated in a roll-ing ball mill (length: 10 cm; diameter:
11.5 cm; 8 steel balls of 2 cm diameter) for 5 minutes at a speed of rotation of 100 min~l.
After the abrasion test had bee~ carried out, the mean particle diameter was still 720 ~m, which corresponds to a decrease of 20~.
Example 7 (according to the invention) Example 2 was repeated with the modification that the exit gas from the rotary kiln was extracted at two points, namely, apart from the region where the amorphous sodium disilicate having a water content of 19.4% by weight is introduced, additionally at a point in the rotary kiln which was at a distance of about 2 m from the said introduction region in the direction of the rotary tube axis. The two exit gas streams were combined and the solids contained therein were precipitated by means of a heat-resistant hose filter. The precipitated solids were re-introduced into the rotary kiln together with the amorphous sodium disilicate having a water content of 19.4~ by weight, so that no sodium disilicate was lost.
As a result, the throughput of the rotary kiln rose to 70 kg/hour, but nevertheless there was no sticky material in the interior of the rotary kiln.
.. ~ . .. . .. . . . .. .
2B2~73 _ 9 Example 8 (comparison example) Example 2 was repeated with the modification that the hot gas entering at the top of the hot-air spray tower had a temperature of 330C. The temperature of the silicate/gas mixture leaving the spray tower was 140C. The sodium disilicate precipitated on the hose filter had a bulk density of 250 g/l, a water content (determined as the loss on ignition at 700C) of 17.9% by weight and a mean particle diameter of 60 ~m. This sodium disilicate was very dusty.
Example 9 (comparison example) Example 2 was repeated with the modification that the rotary kiln was insulated only in such a way that, at a temperature of 490C in the interior of the rotary kiln, a m~;mllm temperature of 150C occurred on its outer skin. As a result, large areas of sticking material formed on the inner wall of the rotary kiln, which fre-quently had to be knocked off mech~n;cally. From the rotary kiln, a product was discharged, some of which had the size of footballs and was very difficult to comminute by the mechAnic~l crusher.
Example 10 (comparison example) Example 2 was repeated with the modification that the sodium disilicate comminuted by means of the mechanical crusher was ground to a mean particle diameter of 83 ~m, using an impact disk mill at 10,000 min~l. ~he ground product had a gray tinge and showed an iron content of 0.02% by weight.
r~ ______ __ _
202~07~
Example 1 (according to the state of the art) In a hot-air spray tower (exit gas temperature: 145C), amorphous sodium disilicate having a 1088 on ignition of 19~ at 700C and a bulk density of 220 g/l was produced rom a waterglass solution having a solids content of 45%.
60 kg/hour of amorphous sodium disilicate having a water content (determined as the 1088 on ignition at 700C) of 18% by weight and 15 kg/h of a recycle material, which had been obtained by comminution of a product, obtained in a previous batch, to less than 250 ~m, were charged via a metering screw to a directly fired rotary kiln (length: 5 m; diameter: 78 cm; inclination: 1.2) at its end opposite the flame, while the crystalline product was discharged from the flame side. The temperature at the hottest point in the rotary kiln was 740C.
No material sticking to the wall of the rotary kiln was formed; the discharged sodium disilicate was largely pulverulent.
~Ample 2 (according to the invention) Sand (99 percent by weight of SiO2; grain size 90%
< 0.5 mm) and 50 percent by weight sodium hydroxide solu-tion in an SiO2/Na2O molar ratio of 2.15 : 1 were filled into a nickel-lined cylindrical autoclave fitted with a stirrer device. With the autoclave being stirred, the mixture was heated to 200C by injecting steam (16 bar) and held for 60 minutes at this temperatùre. The content of the autoclave was then let down through a flash vessel into a tank and, after the addition of 0.3% by weight of perlite as a filter aid, filtered at 90C through a disk pressure filter to separate off the insoluble matter. As the filtrate, a clear waterglass solution having an SiO2/Na2O molar ratio of 2.04 : 1 was obtained. The solids content was adjusted to 50% by dilution with water.
2~ 73 ~ - 6 -The waterglass solution was sprayed in a hot-air spray tower which was fitted with a disk atomizer and which was heated via a gas-fired combustion chamber and connected to a pneumatically cleaning hose filter for precipitating the product, the combustion chamber having been adjusted in such a way that the hot gas entering at the tower top had a temperature of 260C. The rate of the waterglass solution to be sprayed was adjusted such that the tem-perature of the silicate/gas mixture leaving the spray tower was 105C. The residence time was calculated to be 16 seconds from the volume of the spray tower and the gas throughput through the spray tower. The amorphous sodium disilicate precipitated on the hose filter had, at a low dusting te~ency, a bulk density of 480 g/l, an iron content of 0.01~ by weight, an SiO2/Na2O ratio of 2.04:1 and a water content (deterrined as the loss on ignition at 700C) of 19.4%; its mean particle diameter was 52 ~m.
The rotary kiln described in Example 1 had been insulated by several plies of mineral wool and a sheet metal jacket in such a way that, at a temperature of 390C in the interior of the rotary kiln, a ~-~imllm temperature of 38C occurred on its outer skin. 60 kg of the amorphous sodium disilicate were introduced per hour into this rotary kiln, no sticky material being formed. The amor-phous sodium disilicate (Na2Si2O5) leaving the rotary kiln and showing a water content of 0.7% by weight (determined as the loss on ignition at 700C) was comminuted by means of a mechanical crusher to a grain size of less than 6 mm and, after interm~Ai~te cooling, ground on a disk mill (diameter: 30 cm) at 400 min~1 to a mean particle diameter of 95 ~m, the iron content of the ground product being identical to that of the sodium disilicate introduced into the rotary kiln.
The exit gas from the rotary kiln was extracted in the region where the amorphous sodium disilicate having a water content (det~rmin~A as the loss on ignition at 700C) of 19.4% by weight was introduced, and fed to a scrubbing tower. 3 kg of sodium disilicate per hour were discharged with the exit gas.
The residual hardness of the sodium disilicate thus produced was 2.5 mg/l of Ca and less than 1 mg/l of Mg.
Example 3 (according to the invention) Example 2 was repeated with the modification that the temperature was 300C in the interior of the rotary kiln and 35C on its outer skin. The amorphous sodium disili-cate leaving the rotary kiln here had a water content (determined as the loss on ignition at 700C) of 5% by weight. The residual hardness of the sodium disilicate produced in this way was 3.5 mg/l of Ca and 1.5 mg/l of Mg.
Example 4 (according to the invention) The product obtained according to Example 2 having a mean particle diameter of 95 ~m was further comminuted by m~nS of a fluid-bed opposed jet mill with an integrated mechanical classifier device. Depending on the set speed of rotation of the classifier, an attrition-free sodium disilicate having a mean particle diameter of 2 to 15 ~m was obtained.
Example 5 (according to the invention) The product obtained according to Example 2 was further comminuted by means of a porcelain-lined ball mill filled with corlln~um balls. An attrition-free sodium disilicate having a mean particle diameter of 5 to 14 ~m, depending on the grinding time, was obtained.
ple 6 (according to the invention) The product obtained according to Example 2 was processed in a roll compactor having a pressing force of the . . _ . . _ _ = . _ .
compacting rolls of 30 kN/cm of roll width with subse-quent comminlltion of the flakes in a screen granulator to give dust-free granules having a mean particle diameter of 900 ~m, a bulk density of 870 g/l and a high abrasion resistance.
For the determ;n~tion of the abrasion resis-tance, 50 g of granules are treated in a roll-ing ball mill (length: 10 cm; diameter:
11.5 cm; 8 steel balls of 2 cm diameter) for 5 minutes at a speed of rotation of 100 min~l.
After the abrasion test had bee~ carried out, the mean particle diameter was still 720 ~m, which corresponds to a decrease of 20~.
Example 7 (according to the invention) Example 2 was repeated with the modification that the exit gas from the rotary kiln was extracted at two points, namely, apart from the region where the amorphous sodium disilicate having a water content of 19.4% by weight is introduced, additionally at a point in the rotary kiln which was at a distance of about 2 m from the said introduction region in the direction of the rotary tube axis. The two exit gas streams were combined and the solids contained therein were precipitated by means of a heat-resistant hose filter. The precipitated solids were re-introduced into the rotary kiln together with the amorphous sodium disilicate having a water content of 19.4~ by weight, so that no sodium disilicate was lost.
As a result, the throughput of the rotary kiln rose to 70 kg/hour, but nevertheless there was no sticky material in the interior of the rotary kiln.
.. ~ . .. . .. . . . .. .
2B2~73 _ 9 Example 8 (comparison example) Example 2 was repeated with the modification that the hot gas entering at the top of the hot-air spray tower had a temperature of 330C. The temperature of the silicate/gas mixture leaving the spray tower was 140C. The sodium disilicate precipitated on the hose filter had a bulk density of 250 g/l, a water content (determined as the loss on ignition at 700C) of 17.9% by weight and a mean particle diameter of 60 ~m. This sodium disilicate was very dusty.
Example 9 (comparison example) Example 2 was repeated with the modification that the rotary kiln was insulated only in such a way that, at a temperature of 490C in the interior of the rotary kiln, a m~;mllm temperature of 150C occurred on its outer skin. As a result, large areas of sticking material formed on the inner wall of the rotary kiln, which fre-quently had to be knocked off mech~n;cally. From the rotary kiln, a product was discharged, some of which had the size of footballs and was very difficult to comminute by the mechAnic~l crusher.
Example 10 (comparison example) Example 2 was repeated with the modification that the sodium disilicate comminuted by means of the mechanical crusher was ground to a mean particle diameter of 83 ~m, using an impact disk mill at 10,000 min~l. ~he ground product had a gray tinge and showed an iron content of 0.02% by weight.
r~ ______ __ _
Claims (10)
1. A process for producing amorphous sodium silicates having a water content of 0.3 to 6% by weight and an SiO2/Na2O
molar ratio of (1.9 to 2.8) : 1 from a waterglass solu-tion containing at least 20% by weight of solids, which comprises a) obtaining the waterglass solution by reacting quartz sand with sodium hydroxide solution in an SiO2/Na2O
molar ratio of (2.0 to 2.8) : 1 at temperatures from 180 to 240°C and pressures from 10 to 30 bar, b) treating the waterglass solution in a spray-drying zone with hot air at 200 to 300°C for a residence time of 10 to 25 seconds and at a temperature of the exit gas leaving the spray-drying zone of 90 to 130°C, to form a pulverulent amorphous sodium sili-cate having a water content (determined as the loss on ignition at 700°C) of 15 to 23% by weight and a bulk density of more than 300 g/l, c) introducing the pulverulent sodium silicate accord-ing to b) into an obliquely arranged rotary kiln fitted with devices for moving solids and treating it therein with flue gas in counter-current at temperatures from 250 to 500°C for 1 to 60 minutes, the rotary kiln being insulated in such a way that its outside wall temperature is less than 60°C, and d) comminuting the amorphous sodium silicate emerging from the rotary kiln by means of a mechanical crusher to grain sizes of 0.1 to 12 mm.
molar ratio of (1.9 to 2.8) : 1 from a waterglass solu-tion containing at least 20% by weight of solids, which comprises a) obtaining the waterglass solution by reacting quartz sand with sodium hydroxide solution in an SiO2/Na2O
molar ratio of (2.0 to 2.8) : 1 at temperatures from 180 to 240°C and pressures from 10 to 30 bar, b) treating the waterglass solution in a spray-drying zone with hot air at 200 to 300°C for a residence time of 10 to 25 seconds and at a temperature of the exit gas leaving the spray-drying zone of 90 to 130°C, to form a pulverulent amorphous sodium sili-cate having a water content (determined as the loss on ignition at 700°C) of 15 to 23% by weight and a bulk density of more than 300 g/l, c) introducing the pulverulent sodium silicate accord-ing to b) into an obliquely arranged rotary kiln fitted with devices for moving solids and treating it therein with flue gas in counter-current at temperatures from 250 to 500°C for 1 to 60 minutes, the rotary kiln being insulated in such a way that its outside wall temperature is less than 60°C, and d) comminuting the amorphous sodium silicate emerging from the rotary kiln by means of a mechanical crusher to grain sizes of 0.1 to 12 mm.
2. The process as claimed in claim 1, wherein the comminuted sodium silicate is ground by means of a mill to grain sizes of 2 to 400 µm.
3. The process as claimed in claim 2, wherein a mechanical mill running at a circumferential speed of 0.5 to 60 m/s is used.
4. The process as claimed in claim 2, wherein an air jet mill is used.
5. The process as claimed in claim 2, wherein a ceramically lined ball mill is used.
6. The process as claimed in claim 2, wherein a ceramically lined vibratory mill is used.
7. The process as claimed in claim 1, wherein the exit gas from the rotary kiln is extracted in the central region thereof and in the region of the end where the pulveru-lent amorphous sodium silicate having a water content of 15 to 23% by weight is introduced, and purified by means of a dry dust filter, the sodium silicate taken from the dry dust filter being quasi-continuously admixed to the pulverulent amorphous sodium silicate destined to be introduced into the rotary kiln.
8. The process as claimed in claim 1, wherein the ground sodium silicate is fed to a roll compactor, by means of which it is compressed at a roll-pressing force of 20 to 40 kN/cm of roll width to give compact pieces.
9. The process as claimed in claim 8, wherein the compact pieces are, after pre-comminution by forcing them through screens, processed to give granules having a bulk density of 700 to 1000 g/l.
10. The process as claimed in claim 1, wherein amorphous sodium silicates having a water content of 0.5 to 2% by weight are produced.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3935464.4 | 1989-10-25 | ||
| DE3935464 | 1989-10-25 | ||
| DEP4004625.7 | 1990-02-15 | ||
| DE4004625 | 1990-02-15 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2025073A1 CA2025073A1 (en) | 1991-04-26 |
| CA2025073C true CA2025073C (en) | 1995-07-18 |
Family
ID=25886412
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002025073A Expired - Fee Related CA2025073C (en) | 1989-10-25 | 1990-09-11 | Process for producing sodium silicates |
Country Status (17)
| Country | Link |
|---|---|
| EP (1) | EP0425427B1 (en) |
| JP (1) | JPH0669891B2 (en) |
| KR (1) | KR0143991B1 (en) |
| AR (2) | AR247369A1 (en) |
| BR (1) | BR9005386A (en) |
| CA (1) | CA2025073C (en) |
| DE (1) | DE4031849A1 (en) |
| DK (1) | DK0425427T3 (en) |
| ES (1) | ES2047897T3 (en) |
| FI (1) | FI905210A0 (en) |
| HR (1) | HRP921199B1 (en) |
| LV (1) | LV10764B (en) |
| NO (1) | NO904604L (en) |
| PT (1) | PT95664A (en) |
| RU (1) | RU2039701C1 (en) |
| SI (1) | SI9012000A (en) |
| TR (1) | TR24995A (en) |
Families Citing this family (44)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8904007D0 (en) * | 1989-02-22 | 1989-04-05 | Procter & Gamble | Stabilized,bleach containing,liquid detergent compositions |
| DE4107231A1 (en) * | 1991-03-07 | 1992-09-10 | Hoechst Ag | METHOD FOR PRODUCING SODIUM SILICATE |
| DE4330868A1 (en) * | 1993-09-11 | 1995-03-16 | Hoechst Ag | Process for preparing granular sodium silicate |
| DE4400024A1 (en) * | 1994-01-03 | 1995-07-06 | Henkel Kgaa | Silicate builders and their use in detergents and cleaning agents as well as multi-component mixtures for use in this field |
| US5691295A (en) * | 1995-01-17 | 1997-11-25 | Cognis Gesellschaft Fuer Biotechnologie Mbh | Detergent compositions |
| JP3312816B2 (en) * | 1994-07-14 | 2002-08-12 | 株式会社トクヤマ | Amorphous sodium silicate powder and method for producing the same |
| DE19509303A1 (en) * | 1995-03-15 | 1996-09-19 | Henkel Kgaa | Silicate builder by tempering piece glass |
| DE19515072A1 (en) * | 1995-04-28 | 1996-10-31 | Cognis Bio Umwelt | Detergent containing cellulase |
| JP4156029B2 (en) * | 1995-11-09 | 2008-09-24 | ピーキュー ネーデルランド ビー．ブイ． | High bulk density sodium silicate |
| DE19545729A1 (en) | 1995-12-08 | 1997-06-12 | Henkel Kgaa | Bleach and detergent with an enzymatic bleaching system |
| DE19600018A1 (en) | 1996-01-03 | 1997-07-10 | Henkel Kgaa | Detergent with certain oxidized oligosaccharides |
| DE19605688A1 (en) * | 1996-02-16 | 1997-08-21 | Henkel Kgaa | Transition metal complexes as activators for peroxygen compounds |
| DE19620411A1 (en) | 1996-04-01 | 1997-10-02 | Henkel Kgaa | Transition metal amine complexes as activators for peroxygen compounds |
| US6235695B1 (en) | 1996-04-01 | 2001-05-22 | Henkel Kommanditgesellschaft Auf Aktien | Cleaning agent with oligoammine activator complexes for peroxide compounds |
| DE19616693A1 (en) * | 1996-04-26 | 1997-11-06 | Henkel Kgaa | Enol esters as bleach activators for detergents and cleaning agents |
| DE19713852A1 (en) | 1997-04-04 | 1998-10-08 | Henkel Kgaa | Activators for peroxygen compounds in detergents and cleaning agents |
| DE19732749A1 (en) | 1997-07-30 | 1999-02-04 | Henkel Kgaa | Detergent containing glucanase |
| DE19732750A1 (en) | 1997-07-30 | 1999-02-04 | Henkel Kgaa | Cleaning agent containing glucanase for hard surfaces |
| DE19732751A1 (en) | 1997-07-30 | 1999-02-04 | Henkel Kgaa | New Bacillus beta glucanase |
| DE19824705A1 (en) | 1998-06-03 | 1999-12-09 | Henkel Kgaa | Detergents and cleaning agents containing amylase and protease |
| DE19914811A1 (en) | 1999-03-31 | 2000-10-05 | Henkel Kgaa | Detergent compositions containing a bleaching agent include a combination of a cyanomethyl ammonium salt bleach activator and an enzyme |
| DE10058645A1 (en) | 2000-11-25 | 2002-05-29 | Clariant Gmbh | Use of cyclic sugar ketones as catalysts for peroxygen compounds |
| DE10102248A1 (en) | 2001-01-19 | 2002-07-25 | Clariant Gmbh | Use of transition metal complexes with oxime ligands as bleach catalysts |
| CN1575308B (en) | 2001-10-22 | 2010-04-28 | 汉高两合股份公司 | Cotton active, dirt removing urethane-based polymers |
| DE102005026544A1 (en) | 2005-06-08 | 2006-12-14 | Henkel Kgaa | Reinforcement of cleaning performance of detergents by polymer |
| DE102005039580A1 (en) | 2005-08-19 | 2007-02-22 | Henkel Kgaa | Color protecting detergent |
| DE102006012018B3 (en) | 2006-03-14 | 2007-11-15 | Henkel Kgaa | Color protecting detergent |
| DE102007023870A1 (en) | 2007-05-21 | 2008-11-27 | Henkel Ag & Co. Kgaa | Use of an active agent containing (1,3)dioxolan-2-one compound or (1,3)diazepan-2-one compound, and a polymer, for strengthening the primarily washing power of the detergent in the washing of textile oil- and/or fat-containing dirt |
| DE102007038453A1 (en) | 2007-08-14 | 2009-02-19 | Henkel Ag & Co. Kgaa | Use of polycarbonate, polyurethane and/or polyurea polyorganosiloxane compounds or their acid addition compound and (1,3)-dioxolan-2-one or (1,3)-diazepan-2-one compound and polymer for fixing fragrance on hard and/or soft surfaces |
| DE102007023827A1 (en) | 2007-05-21 | 2008-11-27 | Henkel Ag & Co. Kgaa | Use of polycarbonate, polyurethane and/or polyurea-polyorganosiloxane compounds or their acid addition compounds and/or salts to improve the cleaning efficiency of laundry detergents during washing textiles |
| DE102007023874A1 (en) | 2007-05-21 | 2008-11-27 | Henkel Ag & Co. Kgaa | Use of polycarbonate, polyurethane and/or polyurea polyorganosiloxane compounds or their acid addition compound and (1,3)-dioxolan-2-one or (1,3)-diazepan-2-one compound and polymer for fixing fragrance on hard and/or soft surfaces |
| DE102007038456A1 (en) | 2007-08-14 | 2009-02-19 | Henkel Ag & Co. Kgaa | Use of polycarbonate, polyurethane and/or polyurea-polyorganosiloxane compounds or their acid addition compounds and/or salts to improve the cleaning efficiency of laundry detergents during washing textiles |
| DE102007016383A1 (en) | 2007-04-03 | 2008-10-09 | Henkel Ag & Co. Kgaa | Use of (1,3)dioxolan-2-one or (1,3)-diazepan-2-one compound for the fixation of fragrances on hard and/or smooth surfaces e.g. textiles |
| DE102007016391A1 (en) | 2007-04-03 | 2008-10-09 | Henkel Ag & Co. Kgaa | Detergent or cleaning agent for preventing transfer of textile color of colored textiles from uncolored or different colored textiles in laundry, particularly in tenside containing aqueous solution, has color transfer inhibitor |
| DE102011010818A1 (en) | 2011-02-10 | 2012-08-16 | Clariant International Ltd. | Use of transition metal complexes as bleaching catalysts in detergents and cleaners |
| WO2013123981A1 (en) | 2012-02-21 | 2013-08-29 | Henkel Ag & Co. Kgaa | Color protection detergent |
| DE102012220241A1 (en) | 2012-11-07 | 2014-05-08 | Henkel Ag & Co. Kgaa | Polymers with polar groups as soil release assets |
| ES2562109T3 (en) | 2013-05-22 | 2016-03-02 | Henkel Ag&Co. Kgaa | Detergent with color protection |
| US20170247638A1 (en) | 2014-10-20 | 2017-08-31 | Henkel Ag & Co. Kgaa | Colour protection detergent |
| EP3209759B1 (en) | 2014-10-21 | 2018-12-05 | Henkel AG & Co. KGaA | Anti-grey detergent |
| EP3680317B1 (en) | 2019-01-11 | 2022-08-24 | Henkel AG & Co. KGaA | Colour protection detergents |
| EP4105305A1 (en) | 2021-06-15 | 2022-12-21 | Henkel AG & Co. KGaA | Stable viscous dilutable cleaning composition |
| EP4105306A1 (en) | 2021-06-15 | 2022-12-21 | Henkel AG & Co. KGaA | Super-concentrated dilutable manual dishwashing detergent composition |
| EP4186969A1 (en) | 2021-11-26 | 2023-05-31 | Henkel AG & Co. KGaA | Super-concentrated dilutable powder for dishwashing application |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1517891A (en) * | 1922-09-01 | 1924-12-02 | Ind Waste Products Corp | Powdered sodium silicate and process of preparing the same |
| US3838192A (en) * | 1971-10-28 | 1974-09-24 | Huber Corp J M | Production of alkali metal polysilicates |
| US4586177A (en) * | 1983-11-15 | 1986-04-29 | M/A-Com Dcc, Inc. | Integrated narrowband and wideband TDMA networks |
| DE3423945A1 (en) * | 1984-06-29 | 1986-01-09 | Henkel KGaA, 4000 Düsseldorf | METHOD AND DEVICE FOR THE CONTINUOUS HYDROTHERMAL PRODUCTION OF SODIUM SILICATE SOLUTIONS |
| DE3718350A1 (en) * | 1987-06-01 | 1988-12-22 | Hoechst Ag | METHOD FOR PRODUCING CRYSTALLINE SODIUM SILICATES WITH LAYER STRUCTURE |
-
1990
- 1990-09-11 CA CA002025073A patent/CA2025073C/en not_active Expired - Fee Related
- 1990-10-08 EP EP90710027A patent/EP0425427B1/en not_active Expired - Lifetime
- 1990-10-08 DK DK90710027.5T patent/DK0425427T3/en active
- 1990-10-08 ES ES90710027T patent/ES2047897T3/en not_active Expired - Lifetime
- 1990-10-08 DE DE4031849A patent/DE4031849A1/en not_active Withdrawn
- 1990-10-23 AR AR90318162A patent/AR247369A1/en active
- 1990-10-23 TR TR90/1034A patent/TR24995A/en unknown
- 1990-10-23 AR AR90318163A patent/AR243478A1/en active
- 1990-10-23 FI FI905210A patent/FI905210A0/en not_active IP Right Cessation
- 1990-10-23 KR KR1019900016931A patent/KR0143991B1/en not_active IP Right Cessation
- 1990-10-24 PT PT95664A patent/PT95664A/en not_active Application Discontinuation
- 1990-10-24 BR BR909005386A patent/BR9005386A/en not_active IP Right Cessation
- 1990-10-24 JP JP2284528A patent/JPH0669891B2/en not_active Expired - Lifetime
- 1990-10-24 SI SI9012000A patent/SI9012000A/en unknown
- 1990-10-24 RU SU904831297A patent/RU2039701C1/en active
- 1990-10-24 NO NO90904604A patent/NO904604L/en unknown
-
1992
- 1992-11-06 HR HRP-2000/90A patent/HRP921199B1/en not_active IP Right Cessation
-
1993
- 1993-05-04 LV LVP-93-278A patent/LV10764B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| PT95664A (en) | 1991-09-13 |
| HRP921199A2 (en) | 1995-08-31 |
| RU2039701C1 (en) | 1995-07-20 |
| KR910007804A (en) | 1991-05-30 |
| CA2025073A1 (en) | 1991-04-26 |
| JPH03170320A (en) | 1991-07-23 |
| EP0425427A2 (en) | 1991-05-02 |
| BR9005386A (en) | 1991-09-17 |
| AR243478A1 (en) | 1993-08-31 |
| JPH0669891B2 (en) | 1994-09-07 |
| SI9012000A (en) | 1997-12-31 |
| AR247369A1 (en) | 1994-12-29 |
| HRP921199B1 (en) | 1998-04-30 |
| LV10764B (en) | 1995-12-20 |
| ES2047897T3 (en) | 1994-03-01 |
| NO904604L (en) | 1991-04-26 |
| DE4031849A1 (en) | 1991-05-02 |
| KR0143991B1 (en) | 1998-07-15 |
| NO904604D0 (en) | 1990-10-24 |
| DK0425427T3 (en) | 1994-02-21 |
| TR24995A (en) | 1992-09-01 |
| EP0425427B1 (en) | 1993-12-15 |
| LV10764A (en) | 1995-08-20 |
| EP0425427A3 (en) | 1992-03-11 |
| FI905210A0 (en) | 1990-10-23 |
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