Hydraulic and earth engineering – Fluid control – treatment – or containment – Fluid storage in earthen cavity
Patent
1995-07-10
1996-10-01
Schoeppel, Roger J.
Hydraulic and earth engineering
Fluid control, treatment, or containment
Fluid storage in earthen cavity
405264, 166295, B65G 500
Patent
active
055607365
DESCRIPTION:
BRIEF SUMMARY
The invention concerns a method for sealing out water leakage from geological rock formations according to the general idea of the claim.
It is known from U.S. Pat. No. 4,454,252 how to inject fast-reacting polyurethane binary component systems of polyol and isocyanate to stop and seal water leakage from geological rock formations. The two components are blended in a static mixer immediately before entering the rocks. When making contact with water, they form a foam and harden without water and without forming foam. Since the initially injected material displaces the water, the subsequently injected resin forms an unfoamed and, thus, permanently dense water block. However, if the water leakage is considerable, the two components become intensively mixed with the water before the reaction can occur. The result is that the water and polyol form a stable emulsion and the water-insoluble isocyanate reacts to form polyurea in the form of a brittle foam or sludge, so that a water seal can no longer be achieved.
The purpose of the invention is to provide a method for reliable sealing of even heavy water leakage.
This purpose is achieved, according to the invention, by the characteristic features of the patent claim.
Tests have revealed, surprisingly, that the binary synthetic resin mixture according to the invention takes on a gellike consistency several seconds after the mixing, i.e., generally before leaving the injection lance. Even heavy water flow is not able to break up this mixture, so that the resin hardens undisturbed and only produces foam at its surface, due to the water contact.
In the binary polyurethane resin according to the invention, the isocyanate component is reacted with a polyol component, which contains an unsaturated moiety of primary and secondary diamines or polyamines. The amino compounds react much more quickly than the hydroxyl compounds with these isocyanates. The reaction of the slight amount of amine in the polyol component surprisingly accomplishes a significant increase in viscosity in a few seconds, imparting quasithixotropic properties to the system. The resin mixture no longer flows by gravity, and it must be moved by pump pressure.
The polyisocyanate component a) to be used in the process according to the invention comprises, preferably, polyphenyls-polymethyls-polyisocyanates, such as are produced by aniline/formaldehyde condensation and subsequent phosgenation ("polymeric MDI") or derivates of these polyisocyanates that are liquid at room temperature and possess carbodiimide, biuret, urethane and/or allophanate groups, as well as their prepolymeres, i.e., products of the reaction of polyisocyanates with polyols in deficit quantity. The polyols to be considered for preparation of prepolymeres are the generally known compounds from polyurethane chemistry, preferably long-chain polyols with OH-index below 150 mg KOH/g of substance. The polyisocyanate mixtures that are liquid at room temperature and are produced by phosgenation of aniline/formaldehyde condensates ("polymeric MDI"), as well as their liquid, NCO-group-containing products of reaction with deficient quantities (NCO/OH molar ratio=1:0.005 to 1:0.3) of polyvalent alcohols in the molecular weight range of 62-3000, especially polyols containing ether groups in the molecular weight range of 106-3000, are preferred. Liquid mixtures (at room temperature) of 2,4'- and 4,4'-diisocyanatodiphenylmethane are also suitable as polyisocyanate components a). But basically other polyisocyanates can also be considered according to the invention, such as those familiar from, e.g., DE-OS 28 32 253, page 10 and 11. Most especially preferred are polyisocyanate mixtures of the diphenylmethane series with a viscosity at 25.degree. C. of 50-500 mPa.s with an NCO content of around 30-32 wt. %.
The polyol component b) comprises mixtures of organic polyhydroxyl compounds with OH-index between 30 and 2000, while the OH-index of the mixture is between 200 and 500 mg KOH/g of substance.
The polyhydroxyl compounds are preferably the polyether poly
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Cornely Wolfgang
Czysollek Oliver
Fischer Martin
Mehesch Hans E.
Wobig Dieter
Bergwerksverband GmbH
Schoeppel Roger J.
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