Chemistry of inorganic compounds – Silicon or compound thereof – Oxygen containing
Patent
1992-05-26
1993-08-24
Chaudhuri, Olik
Chemistry of inorganic compounds
Silicon or compound thereof
Oxygen containing
423332, C01B 3332
Patent
active
052386686
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a process for the hydrothermal production of potassium silicate solutions with a high SiO.sub.2 :K.sub.2 O molar ratio by the reaction of quartz sand with aqueous potassium hydroxide solutions to form a potassium silicate solution and with subsequent reaction of this intermediate product with a further crystalline SiO.sub.2 --variant to form a product with a high SiO.sub.2 :K.sub.2 O ratio.
STATEMENT OF RELATED ART
A general overview of the production of aqueous potassium silicate solutions is given in the monographs of Winnacker and Kuechler, Chemische Technologie, volume 3, Anorganische Technologie II, 4th. edition, 1983, p. 54-63 and Ullmanns Encyklopaedie der technischen Chemie, Volume 21, 4th. edition, 1982, p. 409-412.
Of the alkali metal silicates known by the term "water glass", potassium silicate solutions--generally known as potassium water glass--are used among others for technical purposes. Such potassium water glasses usually have a solids content of about 28 to 55% by weight and also a molar ratio of silicon dioxide to potassium oxide of 2.0 to 4.2:1. Potassium water glasses are generally produced on an industrial scale by melting together quartz sand and potassium carbonate in suitable furnaces (tank furnaces/rotary kilns) at temperatures in the range of 1400.degree. to 1500.degree. C. with the splitting-off of carbon dioxide. The melt which hardens on cooling, the solid glass, is then dissolved in water in a further process stage using pressure and elevated temperatures and the solution obtained is optionally filtered, depending on the quality requirement.
This high-temperature melt process is, however, very costly both in equipment and as regards the amounts of energy required and leads moreover to not inconsiderable emissions, such as dust, nitrogen oxides, and sulfur oxides.
In addition to these high-temperature melt processes which are the ones mainly used in industry, there are also known hydrothermal processes for the production of aqueous potassium silicate solutions that are described in a number of patent applications.
These processes start from amorphous silicon dioxide, essentially therefore from flue dusts and naturally occurring amorphous silicon dioxide variants.
The products obtained in the process are only of poor quality due to the usual contaminants in the flue dusts and in the natural amorphous silicon dioxide compounds which are used as starting materials, and can therefore be used only to a limited extent for products of high technical value.
DE-AS 28 26 432 relates to a process for the production of water glass solutions by the reaction of flue dusts which occur in the production of silicon or of ferrosilicon alloys with aqueous alkali metal hydroxide solutions at elevated temperatures and subsequent filtration of the solutions obtained, which is characterized in that flue dust is treated in autoclaves with a 6 to 15% by weight aqueous alkali metal hydroxide solution at temperatures of 120.degree. to 90 .degree. C. and a pressure of 2.9 to 18.6 bars, the weight ratio of alkali metal hydroxide solution to solid flue dust being 2:1 to 5:1. The products of the process have a SiO.sub.2 :K.sub.2 O molar ratio of 3.76:1. The flue dusts used as starting materials have a silicon content of 89 to 98% by weight, which in the embodiments is always 90% by weight; the rest consists of contaminants.
DE-OS 26 09 831 relates to a process for the conversion of silicon dioxide containing, environment polluting exhaust flue dusts from the production of silicon metal and silicon alloys to form silicic acids or silicates, which is characterized in that the following process stages I to III are combined: formation of alkali silicate solutions; constituents by treatment with activated charcoal and/or oxidation agents and separation of the non-dissoluble residue from the solution; acids and/or their salts for the purposes of further purification.
The alkali silicate solutions obtained in this way generally have a SiO.sub.2 :Me.sub.2
REFERENCES:
patent: 3956467 (1976-05-01), Bertorelli
patent: 4770866 (1988-09-01), Christophliemk
patent: 5000933 (1991-03-01), Novotny et al.
patent: 5084262 (1992-01-01), Novotny et al.
Hoff Alfred
Novotny Rudolf
Schuertz Jost
Chaudhuri Olik
Henkel Kommanditgesellschaft auf Aktien
Horton Ken
Jaeschke Wayne C.
Szoke Ernest G.
LandOfFree
Process for production of potassium silicate solutions by the ad does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for production of potassium silicate solutions by the ad, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for production of potassium silicate solutions by the ad will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-827159