CA1145918A - Method for the preparation of water glass solutions - Google Patents
Method for the preparation of water glass solutionsInfo
- Publication number
- CA1145918A CA1145918A CA000328600A CA328600A CA1145918A CA 1145918 A CA1145918 A CA 1145918A CA 000328600 A CA000328600 A CA 000328600A CA 328600 A CA328600 A CA 328600A CA 1145918 A CA1145918 A CA 1145918A
- Authority
- CA
- Canada
- Prior art keywords
- solution
- water glass
- alkali metal
- sio2
- flue dust
- 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
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
- Processing Of Solid Wastes (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Treating Waste Gases (AREA)
- Catalysts (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
This invention is directed to a novel method for the production of water glass solutions whereby flue dust is reacted with from about 6 to 15% by weight aqueous alkali metal hydroxide solution at elevated temperatures and the reaction product is then filtered. Preferably, the reaction takes place at a temperature of from about 120 to 190°C and at a pressure of from 2.9 to 18.6 bars.
This invention is directed to a novel method for the production of water glass solutions whereby flue dust is reacted with from about 6 to 15% by weight aqueous alkali metal hydroxide solution at elevated temperatures and the reaction product is then filtered. Preferably, the reaction takes place at a temperature of from about 120 to 190°C and at a pressure of from 2.9 to 18.6 bars.
Description
s~
Solut]ons o~ alkali silicate, i.e.~ water glass, or alkali water glass, are usually obtained by fusing virtually pure quartz sand with soda, i.e., sodium carbonate, or potash at 1400 to 1500C and subsequently dissolving the glass pieces obtained in water under pressure at elevated temperatures. This method is very elaborate, both in terms of equipment and energy, and requires relatively high energy and investment costs.
It is also known to react amorphous residuary silicic acids with sodium hydroxide solutions to form sodium silicate.
~owever, a disadvantage to this method is that since pure resid-uary silicic acids are not available in sufficient quantities, it is usually necessary to use somewhat contaminated raw materials.
For example, the waste gases formed in the production of-silicon or ferrosilicon alloys in electric furnaces contain solid components - the so called flue dust ~ which are obtained in considera~le amounts as waste products in the puri~ication of these waste gases~ The flue dust consists mostly (from about 89 to 98%) of amorphous silicon oxide, which is contaminated by other metal oxides and carbon.
A method for the preparation of water glass solutions by reacting~these flue dusts with alkali metal hydroxide and water at temperatures between 75 and 100C is described in DOS 2,619,604.
The~water glass solution thus obtained contains, howeve~, impurities which, depending Qn the raw material used, can be removed by filtering the water glass solutions through a presssure filter. Unfortunately the manner in which this filtration is to be effected in practice _ ] ~
5g~
is not further discussed -ln this patent, and a separation of' the urities is deliberately fore~one in the examples. Tests have shol:ln, however~ that the water glass solutions obtained according o this ~atent are barely filtQrable, (See, for example, Comparison _xa,lple 1 below.) Thus, only greatly contaminated water glass is obtained with thls method, and such water glass can be used on~y for a few special technical purposes.
Applicants have surprisingly discovered a method of preparing water glass solutions from the amorphous residuary silicic acid flue dust wherein filterable water glass solutions are prepared and uncontaminated sodium silicate can be recovered.
suc~ uncontaminated sodium silicate has many technical applications.
.
~ .
It is an object of this invention to provide a method for preparing water glass solutions from which uncontaminated wa.,er glass can be recovered.
It is further an object of` this inventlon to provide ~ a method for preparlng water glass solutions from such flue dust - ~ by T,rhich filterable water glass solutions free of` insoluble - ~esidues can be obtained.
These and further objects of the invention will be e~ldent from the discusslons below, ~ . . .
~5~L8 This invention is directed to a method of preparing water glass solutions frorn which uncontaminated water glass can be recovered. More particularly~ this i,nvention is directed to a method for the preparation of water glass solutions by reactin~, flue dust, obtained in the production of silicon or ferrosilicon alloys, with aqueous alkali-metal hydroxide solutions at elevated temperatures, and subsequently filtering the solutions obtained.
According to the method, flue dust is treated in an autoclave with a ~rom about 6 to 15% by weight aqueous alkali metal hydroxide solution at temperatures of from about 120 to 190C and a pressure of from about 2.9 to 18.6 bars, the weight ratio of alkali metal hydroxide solution to solid flue dust being from about 2:1 to 5:1.
.
It was surprisingly found that reac-tion under the indicated condit~ons leads to water glass solutions which can be easily filtered. Thus, water glass free of lnsoluble residues and useful for many purposes can be obtained in good yields frorn these flue 'dusts, which heretofore were merely deposited as waste products.
The term "water glass" is broadly intended to refer to alkali metal silicates~ such as sodium silicate and potassium silicate.
~ ~ .
It is of great importance that the weight ratio of the aqueous alkali metal hydroxide solùtion to the solid flue dust used be at least about 2:1. If this ratio is lower~ a water glass is not obtained but, rather, a solid reaction product which can only be removed from the autoclave by mechanical means.
:`
(See Comparison Example 2). Preferably the weight ratio of alkali metal hydroxide solution to the solid flue dust is in the :
s~
r~n~e of from about 2:1 to 5:1. When reac~ion mixtures with ~;ei~ht rat~os above 5:1 are used, water glass solutions are also produced but the sollltions are usually much th:inner and must L)e concen~rated for further use.
Pre~erably temperatures in the range of ~rom about 120 to 190C are maintained during the reacti.on, s~nce the formation of water glass solutions is temperature~dependent under the indicated reactîon conditionsO This dependency co~reeponds to the desired molax ratlo of SiO2 to Me20 tMe - alkali metal~ in the final product. I~ the production o~ wa~s glass w~th a higher - sil~ca content, e.g., with a molar ratio o~ SiO2 to Me20 of about 4:1, is desired, i~ has been found to be advantageous to keep the reaction temperature in the range of i30 to 170C.
- : . . .
The pressure in the autoclave should be in the range Or ~o~ about 2.9 to 18.6 bars during the reactlon. Higher pressures can generally be used, but they do not lead to better results and - only require more elaborate measures. If pressures near the lo~ r limi~ o~ the preferred pressure range are ko be applied, ~he selected reaction temperature must be given careful considera-t~on. Xn view of the weight ratio of the alkali metal hydroxide J
solution to the s~lid flue dust to be maîntained, the pressure should be nigh enough that the wa~er in the autoclave remain~
in ~he liquid phase at the given tempera~ure. Preferably the ~ressures are in the range of from about 8.8 to 1ll.7 bars.
Bo~h sodium hydroxide and po~assium hydroxide can be used as alkali metal hydroxides~ The aqueous solutio~s used should preferably have an alkali me~al hydroxide content in the ran~e of from about 6 to 15% by weight. ¦~
114~91~
In the practice of the lnventLon, the ~lue dust ernployed is obtained from the production of sillcon or ferrosilicon alloys The flue dust usually has the :~ollowing composltion:
_omponent Percent b~ Welght SiO2 ~9 - 98 SiC 0.2 -- 0~7 C 0.2 - 2.5 23 0-05 -- 2.5 A123 0~1 - 1.5 TiO2 0.01 - 0.05 CaO 0.07 - o.8 rago: 0.2- 1.5 Na20 0.1 ~
K20 0.3 - 2.2 P~ ~ 0.03 - 0.1 ~:~ s 0 03 - 0 . 5 The form in which the flue dust is used is not critical.
It can be used in powder form or in the form of granules or pelleks.
The water glass solutions obtained in the reaction are readily filterable by use of conventional filtration techniques, such as, for example, filtration through a porcelain funnel with Perlo ~ filter or, in the case of more viscous liquids, by means of a presssure fi]ter. The fiItrate represents a residue-free, mostly clear~ yellow water glass composition having a solid5 content of from about 15 to 35% by weight~ depending on khe flue ~ dust and the alkali metal hydroxide solution used. Preferably ;~ the molar ratlo of SiO2 to Me20 ranges from about 2. 2 1 to l~
.~ :
, ~ L59~
~ ater glass, i.e.~ an alka1ilnetal silicate such as sodium or potassium si:Licate, can be recovered from the water glass solution by using known techniques, such as evaporation.
The water glass obtained according to this invention can be used ror various known purposes. For exampleg the water gIass can be used as an additive in detergents or cleansers~ as binder or adhesive for coatings and impregnations, for the pro-duction of fillers, for the preparation of inorganic silicates or silica gels, and the like.
Depending on the intended use of the water glass, decoloration of the slightly colored solutions may be desirable.
; This can be easily achleved, for example, by the addit~on of ; active carbon and subsequent filtration. DecoloratiQn of the water glass solutions is also possible by the use of oxidants, e.g., 30% hydrogen peroxide solution. Water-clear water glass solutions can also be obtained if the flue dust ls treaked with atmospheric oxygen at temperatures of 400 to 600C prior to reaction with alkall metal hydroxide soluti.on.
As mentioned above, the method according to the invention 20 generally leads to a high yield of silicon dioxide~ related to the flue dust used, depending on the reaction conditlons. High yields can be obtained particularly by additional processing of the filter cake remaining after filtration. Due to their porous structure andlarge surface area~ filter cakes still con-tain large quantities of water glass, which can be washed outwith water or with the corresponding diluted alka]i metal hydroxide solution to yield diluted water glass solutions. In a preferred embodiment of the invention, the diluted water glass solutions obtained by washing the filtercakes, are admixed with fresh : ~ :
~5~8 alkali metal hydroxide solution and recycled to be reacted with additional flue dust.
E X A M P L E S
The following exa~.ples are set forth to demonstrate certain embodiments of the invention herein and are not to be construed as limiting the invention hereto.
Example 1 A reaction mixture comprised of 301 g o~ a slurry of granulated flue dust (water content 25%; SiO2 content in the flue dust itself, about 90%), 192 g of 50% aqueous sodium hydro-xide solution and 539 g of water, was charged into a conventional stirring autoclave of chrome-nickel steel with a capacity of two liters. Thus~ the reaction mixture comprised 226 g of flue dust and 806 g of aqueous sodium hydroxide solution with a content of 118.7 g ~aOH/1, the rakio of sslution to solids being 3.57:1.
The autoclave was heated and, when the heating was starte~d, an lnitial pressure of 3.9 bars was generated in the autoclave by use o~ an inert gas. ~'he reaction mixture was then heated to 170C and stirred for two hours at a pressure of 14.7 bars.
Subsequently the reaction mixture was filtered without any difficulty by means of a Perlo ~ filter over porcelaln funnel.
The filtrate obtained was comprised of 429 g of water glass solution having a solids content of 26.9% and a SiO2 : Na20 ratio of 2.5:1 (19.23% Si02, 7.69% Na20).
The remaining filter cake was subsequently washed out twice with distilled water. In the first washwater, 600 g of water glass solution (8.84% SiO2~ 3.59% Na20) were obtained, .
-7- ~
ani, in t'ne second washwater, 465 g of water glass solution .3~% sio2, 2.15% Na20) were obtained.
The total yield of~ Si02 as a dissolved water glass c~.?onent was then 79%.
Unless otherwise noted, the following examples were car~ied out according to the procedure of Example 1.
le 2 . Reaction Mixture:
226 g of flue dust (about 90% Si02) 806 g of sodium hydro~ide solution with a content of 118.7 g NaOH/l ( 192 g of' 50% sodium hydroxide solution and 614 g of water) Ratio of solution to solids: 3.57 :1.
The reaction mixture was heated to 170C and stirred 15 for one nour at 14.7 bars. The reaction mixture was filtered, snd the filtrate was found to be comprlsed of 560 g of water gl3.ss solution with a solids content of 27. 5% and a Si02/Na20 ra~io of 2.64:1 (19.96% sio2~ 7.55% Na20). ~he filter cake was ~:Jashed twice, the f'irst washwater yielding 502 g of' water glass so-ution (9.21~ Si02, 4.05% Na20) and the second washwater yielding 435 g of water glass solution (2.9% sio2, 1.2% Na20).
The total yield of S102 was 84L.
Exam le 3 Reaction Mixture:
225 g of flue dust (about 90% Si02) 808 g of sodium hydroxide solution with a content : of 90.3 g NaOH/l (149 g of 50% sodium hydroxide solution and 659 ~ of' water) Ratio of solution to solids: 3.59:1.
.
~ -8-~S~8 The reaction m.i.xture was heaked to 150C and ~tirred for two hours at 8.8 bars. The reackion mlxture was ~ilkered, and the filtrate was fOUIld to be compri.sed of 618 g of water g~a~s solution with a solids content o~ 2307% and a SiOz~Na20 ra~io of 3.. 33~ .2% SiO2; 5.46% Na20)~ The fil.ter cake was washed t~ e~ the ~irst washwater yielding 267 g of water glass solution (11.81.% SiO2, 3.7% Na20), and the second washwater yielding 344 g of water glass solutiorl (4.94% SiO2g 1.65% Na~O).
The total yield of SiO2 was 79%.
Example_4 .
. Reaction Mixture:
_ .. . :
300 g of flue dust (about 90% SiO2) 777 g of sodium hydroxide solukion with a content - of 96.~% NaoH/l (150 g of 50% sodium hydroxide solukion and 627 g o~ -water) -Ratio o~ solution to solids: 2.59:1.
The reaction mixture was heated to i30C and stirred for one hour at 8.8 bars. The reackion mixture was filtered, and the filtrake was found to be comprised of 510 & of water glass solukion having a solids. content of' 26.3% and a SiO2~Na20 ratio of 3.~5:1 (20~91% SiO2; 5.43~ Na20). The filter cake was.
washed twice, the first washwater yielding 445g`o~ wa~er glass . ~olution (11.62% SiO2;.3.18% Na20), the second washwater yield-ing 435 g of water glass solution (Il.27% SiO2, 1.36% ~a20).
: The total yleld of SiO2 was 64%.
:
Example 5 .
: Reaction Mixture~
~ . i 196 g Or flue dust (abouk 90% SiO2~
846 g o~ sodium hydroxide solution with a content of 70.1 g of ;~aOH/l (119 ~ of 50~ sodium hydroxide solution and 727 g of water).
Rakio of solution to solids: I~.32:1.
_9_ .
~s~
The reacti.on mixture was heated at 150C ~or two hours at ~.8 bars and then filtered to obtain a filtrate comprlsed of 73 g of l.rater glass solution having a solids content of ]9.1%
and a SiO2/Na20 ratio of 3.18~ 4 5jt SiO2; 4.56% Na20). The filter cake was washed twice to obtain, in the first washwater, 37l~ G of water glass solution (5 63% SiO2; 1.91% Na20) and, in the second washwater, 249 g of water glass solution (2.79% SiO2, 1.05~o Na20). The total yield of SiO2 was 76%.
EY.am~le 5 Reaction Mixture:
180 g of flue dust (about 90% SiO2) .
846 g of sodium hydroxide solution with a content of 70.1 g of NaOH/1 (119 g of 50% sodium hydroxide solution and 727 g of water) Ratio of solutlon to solids: 4.7:1 The reaction mixture was heated in the autoclave at 150C for 30 minutes at 8.8 bars. The reaction mixture was fi~t~red, and the filtrate was found to be comprised Or 750 g o~
water glass solution having a solids content of 18.3% and a Si~2/Na20 ratio of 3.02:1 (13.75% SiO2, 4.55% Na20). The filter--cake was washed with distilled water twice, the first washwater comprising 339 g of waterglass solution (5.54% SiO2; 2.03% Na20),:
and the second washwater comp.rising 308 g of water glass solution -~2.11% SiO2; 0.81% Na20). The total yield of SiO2 was 79,0.
:
Exam~le 7 Reaction Mixture:
346 g of flue dust (about 90% SiO2) 728 g of sodium hydroxide solution with a content of 13~.4 g of NaOEI/l (204 g of 50~ sodium hydroxide solution and 52ll g of water) Ratio of solution to solids: 2.1:1 The reaction mixture was heated in an autoc:Lave at 150C for t~o hours at 8.8 hars. After ~he reackion mlx~,ure had cooled, a highly viscous liquid was obtained. This llqu:;d ~ras filtered by means of a pressure ~`i.lter at 90C and 2.9 ~rs ~o produce 334 g of water glass solution having a sol:lds c(~ntent of 33.6% and a SiQ2/Na20 ratio of 3.38-1 (25.94% S:102; 7.67%
Na20). The ~iltercake was washed kwice with distilled ~later~
the first washwater being comprised o~ 772 g of waterglass --(13.84% SiO2; 4.35% Na20) and ~he second washwater bein~ com~sec~
~0 of 560 g of waterglass(4.07% SiO2~ 1.44% Na20~. The total yield of SiO2 was 69%.
. .
Example 8 Production of potash water glass~ i.e.~ potassium ~ilicake. -.
. .
Reaction Mixture . .
280 g of:~lue dus~ (about 90% SiO2~
806 g of ~otassium hydroxide solution with a content of 120 g KOH/1 (114 g o~ 85 . potassium hydroxide solution and 692 g water).
Rakio of solution to solids: 2.88:1 The react..on mixture was heated, wikh stirring~ at :: 170C for kwo hours at 14.7 bars. The reaction mixture was filtered, and the filtrate was found to comprise 804 g of potash . . .
~!ater glass ~'~lut`ion~ having a solids content of 27.1% and a SiO2/K20 ratio o~ 2.41:1 (19.14% SiO2, 7.94% K20), The filtercake was washed with diskilled water twice, the first washwaker comprising 549 g of pokash water glass solution (4.o6~ SiO2; 2.04%
K20) and the second washwater comprisin~ 367 g of pokash wat.er 3o ~lass solution (1.l~5% SiO2; 0.93% K20). The total yield of SiO2 was 72%-.
~ s~
. C~ r~so~ E~amole 1 _ . . . - , ;
In accordance ~tith the data set forth in Rxarnple 2 o~
G~rm2n ~u~lished appli.cation (DO~ 2,61~0l~, rlue dust ~as reacted w~ a~ueous sodium hydroxide wlthou~ the a~plication o~ pressvre.
Reactlcn Mixtu-re:
367 g of ~lue dust (about 90% SiO
848 g of sodium hydroxide solution with a ~onten~
. of 81 g of NaOH/l (138g of 50% sodium hydroxide solution and 710 g o~ water) ~: .
lQ The react~on mixture was heated in an open vessel und~
s~i~in~ to 85C for 30 minutes and subsequently transferred t^
.~no4her cold vessel ~or c~oling. The cooled reaction mixture cc~?rised 1,210 g of wat~r glas~ solution, which could not be.
~lt~red, however, either over a porcelain ~unnel wlth varlous ~ 15 t~p~s ~ lilters (Perlo ~ paper, etc.).or over a pressure ~ilter : (2.~ bar)~
' :, ' ,' ', ', C~-~arison Exam~le 2 Reaction M~xture:
.
500 g of flue dust (about 90~ SiO2) ..
~0 600 g o~ sodium hydroxide solution with a conten~
of 148.4 g NaOH/l (178 g o~ 50% sodlum hydroxide solution and l~22 g of ~ater) Ratio of solution to solids: -1.2:1 The reaction~m~xture was heated to 150C at 8.8 bars.
~: 2~ ~o..eJer, af~er the desired reaction temperature o~ 150~C had been ;~ ~ ~t'~ained, the reaction mixture became solid and could no longer :
~:~ o~ s~irred. Lia,uid wa~er glass could not be ob~ained this ~ray.
, , ' '
Solut]ons o~ alkali silicate, i.e.~ water glass, or alkali water glass, are usually obtained by fusing virtually pure quartz sand with soda, i.e., sodium carbonate, or potash at 1400 to 1500C and subsequently dissolving the glass pieces obtained in water under pressure at elevated temperatures. This method is very elaborate, both in terms of equipment and energy, and requires relatively high energy and investment costs.
It is also known to react amorphous residuary silicic acids with sodium hydroxide solutions to form sodium silicate.
~owever, a disadvantage to this method is that since pure resid-uary silicic acids are not available in sufficient quantities, it is usually necessary to use somewhat contaminated raw materials.
For example, the waste gases formed in the production of-silicon or ferrosilicon alloys in electric furnaces contain solid components - the so called flue dust ~ which are obtained in considera~le amounts as waste products in the puri~ication of these waste gases~ The flue dust consists mostly (from about 89 to 98%) of amorphous silicon oxide, which is contaminated by other metal oxides and carbon.
A method for the preparation of water glass solutions by reacting~these flue dusts with alkali metal hydroxide and water at temperatures between 75 and 100C is described in DOS 2,619,604.
The~water glass solution thus obtained contains, howeve~, impurities which, depending Qn the raw material used, can be removed by filtering the water glass solutions through a presssure filter. Unfortunately the manner in which this filtration is to be effected in practice _ ] ~
5g~
is not further discussed -ln this patent, and a separation of' the urities is deliberately fore~one in the examples. Tests have shol:ln, however~ that the water glass solutions obtained according o this ~atent are barely filtQrable, (See, for example, Comparison _xa,lple 1 below.) Thus, only greatly contaminated water glass is obtained with thls method, and such water glass can be used on~y for a few special technical purposes.
Applicants have surprisingly discovered a method of preparing water glass solutions from the amorphous residuary silicic acid flue dust wherein filterable water glass solutions are prepared and uncontaminated sodium silicate can be recovered.
suc~ uncontaminated sodium silicate has many technical applications.
.
~ .
It is an object of this invention to provide a method for preparing water glass solutions from which uncontaminated wa.,er glass can be recovered.
It is further an object of` this inventlon to provide ~ a method for preparlng water glass solutions from such flue dust - ~ by T,rhich filterable water glass solutions free of` insoluble - ~esidues can be obtained.
These and further objects of the invention will be e~ldent from the discusslons below, ~ . . .
~5~L8 This invention is directed to a method of preparing water glass solutions frorn which uncontaminated water glass can be recovered. More particularly~ this i,nvention is directed to a method for the preparation of water glass solutions by reactin~, flue dust, obtained in the production of silicon or ferrosilicon alloys, with aqueous alkali-metal hydroxide solutions at elevated temperatures, and subsequently filtering the solutions obtained.
According to the method, flue dust is treated in an autoclave with a ~rom about 6 to 15% by weight aqueous alkali metal hydroxide solution at temperatures of from about 120 to 190C and a pressure of from about 2.9 to 18.6 bars, the weight ratio of alkali metal hydroxide solution to solid flue dust being from about 2:1 to 5:1.
.
It was surprisingly found that reac-tion under the indicated condit~ons leads to water glass solutions which can be easily filtered. Thus, water glass free of lnsoluble residues and useful for many purposes can be obtained in good yields frorn these flue 'dusts, which heretofore were merely deposited as waste products.
The term "water glass" is broadly intended to refer to alkali metal silicates~ such as sodium silicate and potassium silicate.
~ ~ .
It is of great importance that the weight ratio of the aqueous alkali metal hydroxide solùtion to the solid flue dust used be at least about 2:1. If this ratio is lower~ a water glass is not obtained but, rather, a solid reaction product which can only be removed from the autoclave by mechanical means.
:`
(See Comparison Example 2). Preferably the weight ratio of alkali metal hydroxide solution to the solid flue dust is in the :
s~
r~n~e of from about 2:1 to 5:1. When reac~ion mixtures with ~;ei~ht rat~os above 5:1 are used, water glass solutions are also produced but the sollltions are usually much th:inner and must L)e concen~rated for further use.
Pre~erably temperatures in the range of ~rom about 120 to 190C are maintained during the reacti.on, s~nce the formation of water glass solutions is temperature~dependent under the indicated reactîon conditionsO This dependency co~reeponds to the desired molax ratlo of SiO2 to Me20 tMe - alkali metal~ in the final product. I~ the production o~ wa~s glass w~th a higher - sil~ca content, e.g., with a molar ratio o~ SiO2 to Me20 of about 4:1, is desired, i~ has been found to be advantageous to keep the reaction temperature in the range of i30 to 170C.
- : . . .
The pressure in the autoclave should be in the range Or ~o~ about 2.9 to 18.6 bars during the reactlon. Higher pressures can generally be used, but they do not lead to better results and - only require more elaborate measures. If pressures near the lo~ r limi~ o~ the preferred pressure range are ko be applied, ~he selected reaction temperature must be given careful considera-t~on. Xn view of the weight ratio of the alkali metal hydroxide J
solution to the s~lid flue dust to be maîntained, the pressure should be nigh enough that the wa~er in the autoclave remain~
in ~he liquid phase at the given tempera~ure. Preferably the ~ressures are in the range of from about 8.8 to 1ll.7 bars.
Bo~h sodium hydroxide and po~assium hydroxide can be used as alkali metal hydroxides~ The aqueous solutio~s used should preferably have an alkali me~al hydroxide content in the ran~e of from about 6 to 15% by weight. ¦~
114~91~
In the practice of the lnventLon, the ~lue dust ernployed is obtained from the production of sillcon or ferrosilicon alloys The flue dust usually has the :~ollowing composltion:
_omponent Percent b~ Welght SiO2 ~9 - 98 SiC 0.2 -- 0~7 C 0.2 - 2.5 23 0-05 -- 2.5 A123 0~1 - 1.5 TiO2 0.01 - 0.05 CaO 0.07 - o.8 rago: 0.2- 1.5 Na20 0.1 ~
K20 0.3 - 2.2 P~ ~ 0.03 - 0.1 ~:~ s 0 03 - 0 . 5 The form in which the flue dust is used is not critical.
It can be used in powder form or in the form of granules or pelleks.
The water glass solutions obtained in the reaction are readily filterable by use of conventional filtration techniques, such as, for example, filtration through a porcelain funnel with Perlo ~ filter or, in the case of more viscous liquids, by means of a presssure fi]ter. The fiItrate represents a residue-free, mostly clear~ yellow water glass composition having a solid5 content of from about 15 to 35% by weight~ depending on khe flue ~ dust and the alkali metal hydroxide solution used. Preferably ;~ the molar ratlo of SiO2 to Me20 ranges from about 2. 2 1 to l~
.~ :
, ~ L59~
~ ater glass, i.e.~ an alka1ilnetal silicate such as sodium or potassium si:Licate, can be recovered from the water glass solution by using known techniques, such as evaporation.
The water glass obtained according to this invention can be used ror various known purposes. For exampleg the water gIass can be used as an additive in detergents or cleansers~ as binder or adhesive for coatings and impregnations, for the pro-duction of fillers, for the preparation of inorganic silicates or silica gels, and the like.
Depending on the intended use of the water glass, decoloration of the slightly colored solutions may be desirable.
; This can be easily achleved, for example, by the addit~on of ; active carbon and subsequent filtration. DecoloratiQn of the water glass solutions is also possible by the use of oxidants, e.g., 30% hydrogen peroxide solution. Water-clear water glass solutions can also be obtained if the flue dust ls treaked with atmospheric oxygen at temperatures of 400 to 600C prior to reaction with alkall metal hydroxide soluti.on.
As mentioned above, the method according to the invention 20 generally leads to a high yield of silicon dioxide~ related to the flue dust used, depending on the reaction conditlons. High yields can be obtained particularly by additional processing of the filter cake remaining after filtration. Due to their porous structure andlarge surface area~ filter cakes still con-tain large quantities of water glass, which can be washed outwith water or with the corresponding diluted alka]i metal hydroxide solution to yield diluted water glass solutions. In a preferred embodiment of the invention, the diluted water glass solutions obtained by washing the filtercakes, are admixed with fresh : ~ :
~5~8 alkali metal hydroxide solution and recycled to be reacted with additional flue dust.
E X A M P L E S
The following exa~.ples are set forth to demonstrate certain embodiments of the invention herein and are not to be construed as limiting the invention hereto.
Example 1 A reaction mixture comprised of 301 g o~ a slurry of granulated flue dust (water content 25%; SiO2 content in the flue dust itself, about 90%), 192 g of 50% aqueous sodium hydro-xide solution and 539 g of water, was charged into a conventional stirring autoclave of chrome-nickel steel with a capacity of two liters. Thus~ the reaction mixture comprised 226 g of flue dust and 806 g of aqueous sodium hydroxide solution with a content of 118.7 g ~aOH/1, the rakio of sslution to solids being 3.57:1.
The autoclave was heated and, when the heating was starte~d, an lnitial pressure of 3.9 bars was generated in the autoclave by use o~ an inert gas. ~'he reaction mixture was then heated to 170C and stirred for two hours at a pressure of 14.7 bars.
Subsequently the reaction mixture was filtered without any difficulty by means of a Perlo ~ filter over porcelaln funnel.
The filtrate obtained was comprised of 429 g of water glass solution having a solids content of 26.9% and a SiO2 : Na20 ratio of 2.5:1 (19.23% Si02, 7.69% Na20).
The remaining filter cake was subsequently washed out twice with distilled water. In the first washwater, 600 g of water glass solution (8.84% SiO2~ 3.59% Na20) were obtained, .
-7- ~
ani, in t'ne second washwater, 465 g of water glass solution .3~% sio2, 2.15% Na20) were obtained.
The total yield of~ Si02 as a dissolved water glass c~.?onent was then 79%.
Unless otherwise noted, the following examples were car~ied out according to the procedure of Example 1.
le 2 . Reaction Mixture:
226 g of flue dust (about 90% Si02) 806 g of sodium hydro~ide solution with a content of 118.7 g NaOH/l ( 192 g of' 50% sodium hydroxide solution and 614 g of water) Ratio of solution to solids: 3.57 :1.
The reaction mixture was heated to 170C and stirred 15 for one nour at 14.7 bars. The reaction mixture was filtered, snd the filtrate was found to be comprlsed of 560 g of water gl3.ss solution with a solids content of 27. 5% and a Si02/Na20 ra~io of 2.64:1 (19.96% sio2~ 7.55% Na20). ~he filter cake was ~:Jashed twice, the f'irst washwater yielding 502 g of' water glass so-ution (9.21~ Si02, 4.05% Na20) and the second washwater yielding 435 g of water glass solution (2.9% sio2, 1.2% Na20).
The total yield of S102 was 84L.
Exam le 3 Reaction Mixture:
225 g of flue dust (about 90% Si02) 808 g of sodium hydroxide solution with a content : of 90.3 g NaOH/l (149 g of 50% sodium hydroxide solution and 659 ~ of' water) Ratio of solution to solids: 3.59:1.
.
~ -8-~S~8 The reaction m.i.xture was heaked to 150C and ~tirred for two hours at 8.8 bars. The reackion mlxture was ~ilkered, and the filtrate was fOUIld to be compri.sed of 618 g of water g~a~s solution with a solids content o~ 2307% and a SiOz~Na20 ra~io of 3.. 33~ .2% SiO2; 5.46% Na20)~ The fil.ter cake was washed t~ e~ the ~irst washwater yielding 267 g of water glass solution (11.81.% SiO2, 3.7% Na20), and the second washwater yielding 344 g of water glass solutiorl (4.94% SiO2g 1.65% Na~O).
The total yield of SiO2 was 79%.
Example_4 .
. Reaction Mixture:
_ .. . :
300 g of flue dust (about 90% SiO2) 777 g of sodium hydroxide solukion with a content - of 96.~% NaoH/l (150 g of 50% sodium hydroxide solukion and 627 g o~ -water) -Ratio o~ solution to solids: 2.59:1.
The reaction mixture was heated to i30C and stirred for one hour at 8.8 bars. The reackion mixture was filtered, and the filtrake was found to be comprised of 510 & of water glass solukion having a solids. content of' 26.3% and a SiO2~Na20 ratio of 3.~5:1 (20~91% SiO2; 5.43~ Na20). The filter cake was.
washed twice, the first washwater yielding 445g`o~ wa~er glass . ~olution (11.62% SiO2;.3.18% Na20), the second washwater yield-ing 435 g of water glass solution (Il.27% SiO2, 1.36% ~a20).
: The total yleld of SiO2 was 64%.
:
Example 5 .
: Reaction Mixture~
~ . i 196 g Or flue dust (abouk 90% SiO2~
846 g o~ sodium hydroxide solution with a content of 70.1 g of ;~aOH/l (119 ~ of 50~ sodium hydroxide solution and 727 g of water).
Rakio of solution to solids: I~.32:1.
_9_ .
~s~
The reacti.on mixture was heated at 150C ~or two hours at ~.8 bars and then filtered to obtain a filtrate comprlsed of 73 g of l.rater glass solution having a solids content of ]9.1%
and a SiO2/Na20 ratio of 3.18~ 4 5jt SiO2; 4.56% Na20). The filter cake was washed twice to obtain, in the first washwater, 37l~ G of water glass solution (5 63% SiO2; 1.91% Na20) and, in the second washwater, 249 g of water glass solution (2.79% SiO2, 1.05~o Na20). The total yield of SiO2 was 76%.
EY.am~le 5 Reaction Mixture:
180 g of flue dust (about 90% SiO2) .
846 g of sodium hydroxide solution with a content of 70.1 g of NaOH/1 (119 g of 50% sodium hydroxide solution and 727 g of water) Ratio of solutlon to solids: 4.7:1 The reaction mixture was heated in the autoclave at 150C for 30 minutes at 8.8 bars. The reaction mixture was fi~t~red, and the filtrate was found to be comprised Or 750 g o~
water glass solution having a solids content of 18.3% and a Si~2/Na20 ratio of 3.02:1 (13.75% SiO2, 4.55% Na20). The filter--cake was washed with distilled water twice, the first washwater comprising 339 g of waterglass solution (5.54% SiO2; 2.03% Na20),:
and the second washwater comp.rising 308 g of water glass solution -~2.11% SiO2; 0.81% Na20). The total yield of SiO2 was 79,0.
:
Exam~le 7 Reaction Mixture:
346 g of flue dust (about 90% SiO2) 728 g of sodium hydroxide solution with a content of 13~.4 g of NaOEI/l (204 g of 50~ sodium hydroxide solution and 52ll g of water) Ratio of solution to solids: 2.1:1 The reaction mixture was heated in an autoc:Lave at 150C for t~o hours at 8.8 hars. After ~he reackion mlx~,ure had cooled, a highly viscous liquid was obtained. This llqu:;d ~ras filtered by means of a pressure ~`i.lter at 90C and 2.9 ~rs ~o produce 334 g of water glass solution having a sol:lds c(~ntent of 33.6% and a SiQ2/Na20 ratio of 3.38-1 (25.94% S:102; 7.67%
Na20). The ~iltercake was washed kwice with distilled ~later~
the first washwater being comprised o~ 772 g of waterglass --(13.84% SiO2; 4.35% Na20) and ~he second washwater bein~ com~sec~
~0 of 560 g of waterglass(4.07% SiO2~ 1.44% Na20~. The total yield of SiO2 was 69%.
. .
Example 8 Production of potash water glass~ i.e.~ potassium ~ilicake. -.
. .
Reaction Mixture . .
280 g of:~lue dus~ (about 90% SiO2~
806 g of ~otassium hydroxide solution with a content of 120 g KOH/1 (114 g o~ 85 . potassium hydroxide solution and 692 g water).
Rakio of solution to solids: 2.88:1 The react..on mixture was heated, wikh stirring~ at :: 170C for kwo hours at 14.7 bars. The reaction mixture was filtered, and the filtrate was found to comprise 804 g of potash . . .
~!ater glass ~'~lut`ion~ having a solids content of 27.1% and a SiO2/K20 ratio o~ 2.41:1 (19.14% SiO2, 7.94% K20), The filtercake was washed with diskilled water twice, the first washwaker comprising 549 g of pokash water glass solution (4.o6~ SiO2; 2.04%
K20) and the second washwater comprisin~ 367 g of pokash wat.er 3o ~lass solution (1.l~5% SiO2; 0.93% K20). The total yield of SiO2 was 72%-.
~ s~
. C~ r~so~ E~amole 1 _ . . . - , ;
In accordance ~tith the data set forth in Rxarnple 2 o~
G~rm2n ~u~lished appli.cation (DO~ 2,61~0l~, rlue dust ~as reacted w~ a~ueous sodium hydroxide wlthou~ the a~plication o~ pressvre.
Reactlcn Mixtu-re:
367 g of ~lue dust (about 90% SiO
848 g of sodium hydroxide solution with a ~onten~
. of 81 g of NaOH/l (138g of 50% sodium hydroxide solution and 710 g o~ water) ~: .
lQ The react~on mixture was heated in an open vessel und~
s~i~in~ to 85C for 30 minutes and subsequently transferred t^
.~no4her cold vessel ~or c~oling. The cooled reaction mixture cc~?rised 1,210 g of wat~r glas~ solution, which could not be.
~lt~red, however, either over a porcelain ~unnel wlth varlous ~ 15 t~p~s ~ lilters (Perlo ~ paper, etc.).or over a pressure ~ilter : (2.~ bar)~
' :, ' ,' ', ', C~-~arison Exam~le 2 Reaction M~xture:
.
500 g of flue dust (about 90~ SiO2) ..
~0 600 g o~ sodium hydroxide solution with a conten~
of 148.4 g NaOH/l (178 g o~ 50% sodlum hydroxide solution and l~22 g of ~ater) Ratio of solution to solids: -1.2:1 The reaction~m~xture was heated to 150C at 8.8 bars.
~: 2~ ~o..eJer, af~er the desired reaction temperature o~ 150~C had been ;~ ~ ~t'~ained, the reaction mixture became solid and could no longer :
~:~ o~ s~irred. Lia,uid wa~er glass could not be ob~ained this ~ray.
, , ' '
Claims (3)
1. A method for the preparation of water glass solutions which comprises the steps of:
(a) reacting amorphous residuary silicic acid flue dust with a from 6 to 15% by weight aqueous solution of an alkali metal hydroxide at a temperature of from about 120° to 190°C and at a pressure of from about 2.9 to 18.6 bars, the weight ratio of the alkali metal hydroxide solution to the solid flue dust being from about 2:1 to 5:1;
(b) filtering the reaction mixture resulting from step (a) to produce a filtercake and a filtrate comprising water glass solution; and (c) washing the filtercake produced in step (b) at least once with water or a corresponding diluted alkali metal hydroxide solution to produce a diluted water glass solution which is then used together with alkali metal hydroxide solution with additional flue dust.
(a) reacting amorphous residuary silicic acid flue dust with a from 6 to 15% by weight aqueous solution of an alkali metal hydroxide at a temperature of from about 120° to 190°C and at a pressure of from about 2.9 to 18.6 bars, the weight ratio of the alkali metal hydroxide solution to the solid flue dust being from about 2:1 to 5:1;
(b) filtering the reaction mixture resulting from step (a) to produce a filtercake and a filtrate comprising water glass solution; and (c) washing the filtercake produced in step (b) at least once with water or a corresponding diluted alkali metal hydroxide solution to produce a diluted water glass solution which is then used together with alkali metal hydroxide solution with additional flue dust.
2. The method of Claim 1 wherein the alkali metal hydroxide is sodium hydroxide and a solution of sodium silicate is produced.
3. The method of Claim 1 wherein the alkali metal hydroxide is potassium hydroxide and a solution of potassium silicate is produced.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2826432A DE2826432C2 (en) | 1978-06-16 | 1978-06-16 | Process for the production of water glass |
| DEP2826432.6 | 1978-06-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1145918A true CA1145918A (en) | 1983-05-10 |
Family
ID=6041972
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000328600A Expired CA1145918A (en) | 1978-06-16 | 1979-05-29 | Method for the preparation of water glass solutions |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0006202B1 (en) |
| JP (1) | JPS55100217A (en) |
| CA (1) | CA1145918A (en) |
| DE (1) | DE2826432C2 (en) |
| ES (1) | ES481594A1 (en) |
| NO (1) | NO791671L (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102320615A (en) * | 2011-09-11 | 2012-01-18 | 中国科学院过程工程研究所 | Method for preparing precipitated silica by adopting micro-silica fume as raw material |
| CN102424392A (en) * | 2011-09-11 | 2012-04-25 | 中国科学院过程工程研究所 | Method for preparing white carbon black cogeneration nanometer calcium carbonate by integrally utilizing micro silicon powder |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3002834A1 (en) * | 1980-01-26 | 1981-07-30 | Henkel KGaA, 4000 Düsseldorf | METHOD FOR THE HYDROTHERMAL PRODUCTION OF SODIUM SILICATE SOLUTIONS IN A STATIC REACTION CONTAINER |
| US4661291A (en) * | 1984-09-25 | 1987-04-28 | Mitsui Engineering & Shipbuilding Co., Ltd. | Method for fixation of incinerator ash or iodine sorbent |
| DE3902753A1 (en) * | 1989-01-31 | 1990-08-02 | Henkel Kgaa | METHOD FOR THE HYDROTHERMAL PRODUCTION OF POTASSIUM SILICATE SOLUTIONS WITH HIGH SI0 (DOWN ARROW) 2 (DOWN ARROW): K (DOWN ARROW) 2 (DOWN ARROW) 0-MOLE RATIO |
| DE3902751A1 (en) * | 1989-01-31 | 1990-08-02 | Henkel Kgaa | METHOD FOR THE HYDROTHERMAL PRODUCTION OF SODIUM SILICATE SOLUTIONS WITH A HIGH SI0 (DOWN ARROW) 2 (DOWN ARROW): NA (DOWN ARROW) 2 (DOWN ARROW) MOLENE RATIO |
| JP5334043B2 (en) * | 2008-04-04 | 2013-11-06 | 新日鐵住金株式会社 | Water glass manufacturing method |
| WO2012113650A2 (en) | 2011-02-22 | 2012-08-30 | Evonik Degussa Gmbh | Process for preparing aqueous colloidal silica sols of high purity from alkali metal silicate solutions |
| DE102011017783A1 (en) | 2011-04-29 | 2012-10-31 | Evonik Degussa Gmbh | Preparing an aqueous colloidal silica sol, useful to e.g. prepare silica, comprises mixing a water-soluble alkali metal silicate with an acidifying agent, followed by contacting with e.g. a basic anion exchange resin of hydroxyl type |
| DE102011004534A1 (en) | 2011-02-22 | 2012-08-23 | Evonik Degussa Gmbh | Preparing an aqueous colloidal silica sol, useful to prepare silica, comprises mixing a water-soluble alkali metal silicate with an acidifying agent, followed by contacting with a basic anion exchange resin of hydroxyl type, |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4816438B1 (en) * | 1970-10-29 | 1973-05-22 | ||
| JPS4961095A (en) * | 1972-10-17 | 1974-06-13 | ||
| JPS49134599A (en) * | 1973-04-28 | 1974-12-25 | ||
| JPS50119000A (en) * | 1974-03-01 | 1975-09-18 | ||
| JPS50150699A (en) * | 1974-05-27 | 1975-12-03 | ||
| JPS51105500A (en) * | 1975-03-12 | 1976-09-18 | Kao Corp | Orimonojunankazai |
| JPS51119400A (en) * | 1975-04-11 | 1976-10-19 | O K M Eng:Kk | Sodium silicate production |
| DK136708C (en) * | 1975-05-06 | 1978-05-08 | Skamol Skarrehage Molerverk As | PROCEDURE FOR MANUFACTURE OF WATER GLASS IN DISSOLUTED FORM |
| JPS5226515A (en) * | 1975-08-27 | 1977-02-28 | Nippon Chemical Ind | Method of manufacturing hydrated alkali silicate glass |
| DE2609831B2 (en) * | 1976-03-10 | 1979-05-23 | Deutsche Gold- Und Silber-Scheideanstalt Vormals Roessler, 6000 Frankfurt | Process for processing waste dust containing silicon dioxide into precipitated silicas and silicates |
| JPS52142700A (en) * | 1976-05-24 | 1977-11-28 | Raito Kougiyou Kk | Method of producing silicate solution for soil stabilizing agent |
| DE2651446C2 (en) * | 1976-11-11 | 1984-04-19 | Degussa Ag, 6000 Frankfurt | Process for processing waste dust containing silicon dioxide into crystalline zeolitic molecular sieves of type Y with a faujasite structure |
| DE2651384C2 (en) * | 1976-11-11 | 1984-03-15 | Degussa Ag, 6000 Frankfurt | Process for processing waste dusts containing silicon dioxide into crystalline zeolitic molecular sieves of type A. |
-
1978
- 1978-06-16 DE DE2826432A patent/DE2826432C2/en not_active Expired
-
1979
- 1979-05-21 NO NO791671A patent/NO791671L/en unknown
- 1979-05-29 CA CA000328600A patent/CA1145918A/en not_active Expired
- 1979-06-11 EP EP79101860A patent/EP0006202B1/en not_active Expired
- 1979-06-14 JP JP7406679A patent/JPS55100217A/en active Pending
- 1979-06-15 ES ES481594A patent/ES481594A1/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102320615A (en) * | 2011-09-11 | 2012-01-18 | 中国科学院过程工程研究所 | Method for preparing precipitated silica by adopting micro-silica fume as raw material |
| CN102424392A (en) * | 2011-09-11 | 2012-04-25 | 中国科学院过程工程研究所 | Method for preparing white carbon black cogeneration nanometer calcium carbonate by integrally utilizing micro silicon powder |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0006202B1 (en) | 1981-09-16 |
| DE2826432B1 (en) | 1979-12-20 |
| ES481594A1 (en) | 1980-01-16 |
| NO791671L (en) | 1979-12-18 |
| EP0006202A1 (en) | 1980-01-09 |
| JPS55100217A (en) | 1980-07-31 |
| DE2826432C2 (en) | 1980-10-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5215732A (en) | Method for producing alkali metal silicates by heating cristobalite or tempered quartz sand with naoh or koh under atmospheric pressure | |
| JPH05503065A (en) | Method for producing crystalline sodium disilicate in hot water | |
| CA1145918A (en) | Method for the preparation of water glass solutions | |
| US7335342B2 (en) | Process for the preparation of sodium silicate from Kimberlite tailing | |
| US20090022646A1 (en) | Process for hydrothermal production of sodium silicate solutions and precipitated silicas | |
| CA2009038C (en) | Improved process for hydrothermal production of potassium silicate solutions | |
| US5238668A (en) | Process for production of potassium silicate solutions by the addition of tempered quartz to hydrothermally reacted quartz and koh, and hydrothermal reaction thereof | |
| CA2009035A1 (en) | Process for hydrothermal production of sodium silicate solutions | |
| JPS60204613A (en) | Production of high purity silica gel | |
| JPS6212608A (en) | Silica of high purity and production thereof | |
| US4226837A (en) | Process for converting silicon dioxide containing waste flue dust to crystalline zeolitic molecular sieves of type Y with a Faujasite structure | |
| AU628933B2 (en) | Hydrothermal process for preparing sodium silicate solutions with a high si02:na2o molar ratio | |
| DE4019789A1 (en) | PROCESS FOR PREPARING SODIUM SILICATE SOLUTIONS | |
| JPH04503049A (en) | Hydrothermal production method of sodium silicate solution | |
| KR930002231B1 (en) | Process for the production of hydrothermal waterglasses | |
| JPH0264027A (en) | Production of silica glass | |
| SU1049425A1 (en) | Method of producing p zeolite | |
| JPH0516372B2 (en) | ||
| SU1087464A1 (en) | Process for preparing solution of potassium silicate | |
| JPH0581524B2 (en) | ||
| RU2056353C1 (en) | Method of water glass producing | |
| JPH04305031A (en) | Production of silica glass | |
| RU2057069C1 (en) | Method for production of water glass | |
| JPS61270211A (en) | Production of zeolite | |
| JPS58213629A (en) | Production of sodium silicate |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |