U.S. patent number RE31,946 [Application Number 06/566,640] was granted by the patent office on 1985-07-16 for process for consolidating and sealing off geological and artificially deposited rock and earth formations.
This patent grant is currently assigned to Bayer Aktiengesellschaft, Bergwerksverband GmbH. Invention is credited to Rolf Kubens, Hans Mehesch, Frank Meyer, Martin Winkelmann.
United States Patent |
RE31,946 |
Meyer , et al. |
July 16, 1985 |
Process for consolidating and sealing off geological and
artificially deposited rock and earth formations
Abstract
Waterglass solutions are mixed with polyisocyanates and these
emulsions are then left to harden in the formations. Introduction
of the mixture into the formations which are required to be
consolidated, e.g. deposits of coal, is mainly carried out by
forcing the mixture under pressure into bore-holes in the
formations. According to one variation of the process, the
components of the mixture are introduced into the multi-chamber
cartridges which are introduced into the bore-holes and then
destroyed as the components are mixed. Certain additives such as
accelerators, blowing agents, polyols, stabilizers and/or
thixotropic agents are advantageous for the quality of the
composite masses formed by hardening of the mixture.
Inventors: |
Meyer; Frank (Essen,
DE), Mehesch; Hans (Essen, DE), Kubens;
Rolf (Odenthal, DE), Winkelmann; Martin
(Leverkusen, DE) |
Assignee: |
Bergwerksverband GmbH (Essen,
DE)
Bayer Aktiengesellschaft (Leverkusen, DE)
|
Family
ID: |
25778098 |
Appl.
No.: |
06/566,640 |
Filed: |
December 29, 1983 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
127019 |
Mar 4, 1980 |
04307980 |
Dec 29, 1981 |
|
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Current U.S.
Class: |
405/264; 166/295;
521/122; 523/132 |
Current CPC
Class: |
C08G
18/302 (20130101); C08G 18/3895 (20130101); E21D
9/002 (20130101); C09K 17/46 (20130101); E21D
1/10 (20130101); C09K 8/5086 (20130101) |
Current International
Class: |
C08G
18/00 (20060101); C09K 8/508 (20060101); C08G
18/38 (20060101); C09K 17/46 (20060101); C09K
17/40 (20060101); C08G 18/30 (20060101); C09K
8/50 (20060101); E21D 1/00 (20060101); E21D
9/00 (20060101); E21D 1/10 (20060101); C08G
018/76 (); E02B 003/12 (); E02D 003/12 (); E21B
033/138 () |
Field of
Search: |
;166/295,294
;405/264,266 ;521/122 ;523/130-132 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1758185 |
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Nov 1972 |
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DE |
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1784458 |
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Apr 1973 |
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DE |
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48-9325 |
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Mar 1973 |
|
JP |
|
Other References
US. application Ser. No. 930,128..
|
Primary Examiner: Novosad; Stephen J.
Attorney, Agent or Firm: Harsh; Gene Gil; Joseph C. Roy;
Thomas W.
Claims
What is claimed is:
1. A process for consolidating geological rock formations and coal
deposits which comprises
(a) intimately mixing
(i) a waterglass solution,
(ii) a polyisocyanate which does not contain chemically
incorporated emulsifiers selected from the group consisting of
2,4-diisocyanatotoluene; 2,6-diisocyanatotoluene; mixtures of these
isomers; a polyphenyl-polymethylene polyisocyanate which
corresponds to the phosgenation products of the
aniline/formaldehyde condensation reaction; and reaction products
of said phosgenation products with polyhydric alcohols which have
molecular weights ranging from about 62 to 3,000 wherein the NCO/OH
molar ratio is about 1:0.005 to 1:0.3, and
(iii) up to about 30% by weight based on the weight of the
waterglass solution of a compound having at least one
polyisocyanate reactive group and which does not contain chemically
incorporated emulsifiers,
wherein the proportion by weight of component (ii) to component (i)
is in the range of about 75:25 to about 15:85, and
(b) introducing said mixture into said formation or said deposit
which is required to be consolidated and allowing it to react to
form a .[.foamed,.]. hardened composition which adheres to the
surfaces of said formation or said deposit.
2. The process according to claim 1 which comprises adding up to
about 2% by weight, based on the weight of components (i) and (ii),
of a polyaddition accelerator.
3. The process according to claim 2 characterized in that said
accelerator is an organo-metallic compound.
4. The process according to claim 5, characterized in that said
organo-metallic compound is dibutyl tin dilaurate.
5. The process according to claim 2, characterized in that said
accelerator is a tertiary amine.
6. The process according to claim 5, characterized in that said
tertiary amine is triethylamine.
7. The process according to claim 1 which comprises adding a
blowing agent in quantities of up to about 30% by weight, based on
the weight of components (i) and (ii).
8. The process according to claim 7, characterized in that said
blowing agent is selected from the group consisting of acetone,
methylene chloride, monofluorotrichloromethane,
dichlorodifluoromethane and butane.
9. The process according to claim 1, characterized in that the
compound having at least one polyisocyanate reactive group is a
polyhydroxyl compound.
10. The process according to claim 9, characterized in that said
polyhydroxyl compound is a polyether polyol having a hydroxyl
number from about 50-600.
11. The process according to claim 9, characterized in that said
polyhydroxyl compound is a polyester polyol having a hydroxyl
number from about 50-600.
12. The process according to claim 1 which comprises adding
thixotropic agents and emulsifiers to stabilize said mixture.
13. The process according to claim 1 which comprises incorporating
foam stabilizers into said mixture.
14. The process according to claim 1 which comprises introducing
said mixture under pressure through bore-holes or injection lances
into the said formations or said deposits which are required to be
consolidated.
15. The process according to claim 1 which comprises introducing
said components into separate containers of a multi-chamber
cartridge and subsequently mixing said components after their
introduction into said formations or said deposits by destroying
the cartridge.
16. The process according to claim 1, characterized in that the
proportion by weight of polyisocyanate to waterglass solution is in
the range of about 60:40 to about 25:75.
17. The process according to claim 1, characterized in that
component (ii) is a polyphenyl-polymethylene polyisocyanate which
corresponds to the phosgenation products of the
aniline/formaldehyde condensation reaction.
18. A process for consolidating geological rock formations and coal
deposits which comprises
(a) intimately mixing
(i) a waterglass solution,
(ii) a polyisocyanate selected from the group consisting of
2,4-diisocyanatotoluene; 2,6-diisocyanatotoluene; mixtures of these
isomers; a polyphenyl-polymethylene polyisocyanate which
corresponds to the phosgenation products of the
aniline/formaldehyde condensation reaction; and reaction products
of said phosgenation products with polypropylene glycols wherein
the NCO/OH molar ratio is about 1:0.005 to 1:0.3, and
(iii) up to about 30% by weight based on the weight of the
waterglass solution of a compound having at least one
polyisocyanate reactive group and which does not contain polyether
segments containing ethylene oxide units,
wherein the proportion by weight of component (ii) to component (i)
is in the range of about 75:25 to about 15:85, and
(b) introducing said mixture into said formation or said deposit
which is required to be consolidated and allowing it to react to
form a .[.foamed,.]. hardened composition which adheres to the
surfaces of said formation or said deposit.
Description
BACKGROUND OF THE INVENTION
In underground coal mining, consolidation and sealing of geological
and artificially deposited rock and earth formations are carried
out to a very large extent with polyurethane systems, see:
Journal: Gluckauf (1968), pages 666-670;
Journal: Gluckauf (1977), pages 707-711;
Journal: Bergbau (1977), pages 124-129;
German Pat. No. 1,758,185;
German Pat. No. 1,784,458.
Two component polyurethane systems are generally forced under
pressure into the formations which are required to be consolidated.
The starting components used for these systems are generally
commercial polyisocyanates and polyols having a molecular weight
from 400 to 600 and a hydroxyl number of 350 to 400. According to
German Pat. No. 2,436,029, the polyols are rendered flexible with
polyols having a hydroxyl number from 50 to 90 and a molecular
weight from 2,000 to 35,000.
Natural limits to the possibilities of using polyurethane are given
by rock formations which carry water since water destroys the
polyisocyanate and thereby significantly interferes with the
stoichiometric proportions of the reactants. In addition, water and
polyisocyanates preferentially react to form polyureas whch do not
adhere to the cracks and fissures in the rock. Warnings are always
given that in consolidation work carried out with polyurethanes,
water must be kept away from the zones of rock which are required
to be consolidated. See Gluckauf (Journal) (1972), pages 10 to
13.
One fundamental disadvantage of using polyurethanes in coal mining
is that the hardened product is readily combustible. When
substantial quantities of hardened polyurethanes are situated in
fissures in the coal, fire due to spontaneous ignition of coal is
liable to be spread by polyurethanes. Attempts have therefore been
made to overcome the disadvantages of polyurethane by using systems
which are virtually incombustible and obtainable in an aqueous form
so that consolidation may also be carried out in moist or wet
formations.
Extensive experiments, for example, have been carried out with
aqueous formaldehyde-urea solutions. Sufficient consolidation
could, however, not be achieved with these systems because the
products obtained undergo severe shrinkage during the hardening
process.
Attempts have also been made to use water glass solutions for
consolidation. The hardening of water glass solutions requires the
addition of hardeners. Acids and substances which give rise to
acids such as phosphoric acid, sulphonic acid, esters, e.g.
glycerol triacetate, ethyl acetate and other organic substances,
such as formamide and glyoxal are used for this purpose. Calcium
chloride, aluminum sulphate, magnesium chloride, magnesium
sulphate, aluminum chloride and silicofluorides have also been used
as hardeners.
Although relatively coarse sand and gravel can be consolidated to a
certain extent by these processes, e.g. for the purpose of
consolidating building sites, a high degree of consolidation cannot
be achieved because the hardening of water glass is accomplished by
a considerable volumetric shrinkage so that the composite mass
produced becomes detached from the surfaces of the cracks and
fissures.
The present invention solves the problem of providing a process for
the consolidation and sealing of geological and artificially
deposited rock and earth formations which obviates the
disadvantages described above of the known consolidation processes
and achieves satisfactory strength values as well as being
resistant to moisture and non-combustible.
According to the invention, this problem is solved by mixing
intimately polyisocyanate with water glass solutions and leaving
the resulting emulsion to harden in the formation which is required
to be consolidated. The solid masses which form have excellent
adherence to dry and wet geological formations, particularly since
the shrinkage which normally occurs when water glass solutions are
hardened without the addition of polyisocyanates is completely
absent and instead, the bond is strengthened by a certain increase
in volume during hardening. One special advantage of coal mining is
that the hardened consolidating agent is non-inflammable and the
composite mass which forms in the gaps and cracks and the like is
of great strength which is highly advantageous for stabilizing the
formation.
It is surprisingly found that hardened composite masses also adhere
to fatty coal such as coal which has a relatively high bitumen
content, so that excellent consolidation is obtained for every type
of coal.
SUMMARY OF THE INVENTION
The present invention relates to a process for consolidating and
sealing off geological and artificially deposited rock and earth
formations by mixing water glass solutions with polyisocyanates and
allowing these emulsions to harden in the formations. The mixture
may be introduced into the formations which are required to be
consolidated, e.g. deposits of coal, by forcing the mixture under
pressure into bore-holes in the formations. Alternatively,
multi-chamber cartridges containing the water glass solutions and
polyisocyanates in separate compartments are introduced into the
bore-holes and subsequently destroyed in order to mix the
components.
Various additives such as accelerators, blowing agents, polyols,
stabilizers and/or thixotropic agents may also be added to improve
the quantity of the composite masses formed by hardening of the
mixture.
DETAILED DESCRIPTION OF THE INVENTION
The polyisocyanates used for the purpose of the invention may in
principle be any organic polyisocyanates having aliphatically,
cycloaliphatically, araliphatically, aromatically or
heterocyclically bound polyisocyanate groups, e.g. those described
by W. Siefken in "Justus Liebigs Annalen der Chemie" 562, pages
75-136, but it is preferred to use the polyisocyanates with
aromatically bound polyisocyanate groups commonly used in
polyurethane chemistry which are liquid at room temperature.
Examples of these polyisocyanates include 2,4-diisocyanatotoluene,
2,6-diisocyanatotoluene and any mixtures of these isomers ("TDI"),
polyphenyl-polymethylene polyisocyanates which may be prepared by
aniline/formaldehyde condensation followed by phosgenation ("MDI")
and derivatives of these polyisocyanates which contain carbodiimide
groups, biuret groups, urethane groups or allophanate groups and
are liquid at room temperature. The polyisocyanate mixture ("MDI")
which has been obtained by the phosgenation of aniline/formaldehyde
condensates and is liquid at room temperature and its
isocyanate-containing reaction products obtained by reacting them
with sub-equivalent quantities (NCO/OH molar ratio from about
1:0.005 to about 1:0.3) of polyhydric alcohols with molecular
weights ranging from about 62 to 3,000, in particular with polyols
in the molecular weight range of about 134 to 3,000 which contain
ether groups, are particularly preferred.
by "water glass solutions" are meant solutions of sodium and/or
potassium silicate in water. Crude commercial products possibly
containing, for example, calcium silicate, magnesium silicate,
borates and aluminates may also be used. The molar ratio of
SiO.sub.2 :M.sub.2 O (M=metal) may vary within the limits of about
0.5:1 to about 4:1. It is preferred to use water glass solutions
having a ratio of SiO.sub.2 :M.sub.2 O in the range of about 1:1 to
about 2.5:1. The concentration of water glass solution may be
chosen in the range about 25 to 55% by weight, preferably about 40
to 50% by weight.
The proportion by weight of polyisocyanate to water glass in the
mixture to be formed may vary within wide limits, i.e., from about
75:25 to about 15:85. It is preferred to use a ratio by weight of
polyisocyanate to water glass in the region of about 60:40 to about
25:75.
Preparation of the mixture of polyisocyanates and water glass
solutions is a simple procedure. All that is necessary is to mix
the two liquids homogeneously, e.g. by stirring by hand, using
stirrer blades, or with the usual motor driven stirrers. The
emulsions may also be prepared in mixing and dosing apparatus, in
which case the two liquids are delivered to a throughflow mixer
from dosing pumps. The dosing pumps may be, e.g. gear-wheel pumps,
piston pumps or diaphragme groups. The throughflow mixers are, for
example, mixing chambers with driven stirrers or static mixers,
e.g. tubes with variously arranged baffle plates.
The mixture is generally forced into the formation or into
bore-holes in the formation through lances or pipes. Bore-holes
should be closed immediately after the mixture has been forced in
since gelling and subsequent hardening of the mixture begins only
after 30 to 60 seconds. If the mixture is to be introduced into
bore-holes, it is suitably introduced through bore-hole covers
acting as valves, e.g. according to German Pat. No. 2,550,555.
Depending on the nature of the polyisocyanate, the selected mixing
process, the desired degree of foaming of the consolidating agent
and its consistency, it may be advisable to add the following
additivies to the polyisocyanate or to the water glass solution or
the mixture of polyisocyanate and water solution:
1. Accelerators as commonly used in polyurethane chemistry.
Examples include organo-metallic compounds such as dibutyl tin
dilaurate and tertiary amines such as triethylamine. The quantities
added may be up to about 2% by weight, based on the mixture of
polyisocyanate and water glass solution.
2. Blowing agents, e.g. acetone, methylene chloride,
monofluorotrichloromethane, dichlorodifluoromethane and butane. The
quantities added may be up to about 30% by weight, based on the
mixture of polyisocyanate and water glass solution.
3. Compounds having at least one polyisocyanate reactive groups.
These compounds are generally added to the reaction mixture in
quantities of up to about 30% by weight, based on the water glass
solution. Organic polyamines such as ethylene diamine, diethylene
triamine, triethylene tetramine, 4,4'-diaminodiphenyl methane or
2,4'-diaminotoluene may be used, but organic compounds having
alcoholic hydroxyl groups are preferred. These include simple
monohydric or polyhydric, preferably polyhydric alcohols with
molecular weights in the range of about 32 to 200, preferably about
62 to 200, or the usual relatively high molecular weight
polyhydroxyl compounds with molecular weights from about 200 to
5,000, preferably about 200 to 1,000, commonly used in polyurethane
chemistry, e.g. the known polyhydroxyl polyesters or polyhydroxyl
droxyl polyethers. Examples of suitable lower molecular weight
alcohols include methanol, ethanol, propanol, ethylene glycol,
diethylene glycol, triethylene glycol, glycerol and trimethylol
propane. Examples of relatively high molecular weight alcohols
include polyesters of dicarboxylic acids such as phthalic acid,
adipic acid, hexahydrophthalic acid, tetrahydrophthalic acid and/or
maleic acid and the above-mentioned simple alcohols or polyether
polyols such as can be obtaind by alkoxylation, i.e. in particular
by the chemical addition of propylene oxide and/or ethylene oxide
to low molecular weight starter molecules. Water and, for example,
the above-mentioned low molecular weight amines or alcohols which
have at least two active hydrogen atoms are suitable starter
molecules.
Particularly, preferred alcohols are the lastmentioned polyether
polyols with hydroxyl numbers in the region of about 50 to 600. The
alcohols may be added either to the water glass solution or to the
polyisocyanate or as third component to the mixture of
polyisocyanate and water glass. Mixtures containing the compounds
mentioned above as additives have hitherto produced the best
solidification values and therefore constitute a particularly
preferred embodiment of the invention.
4. Emulsifiers, e.g. reaction products of stearylamine and ethylene
oxide, polyether esters of abietic or oleic acid and ethylene
oxide, fatty alcohol polyglycol ethers, alkyl phenol polyglycol
ethers, emulsifiers based on waterglass, e.g. Tegosivin of
Goldtschmit AG, amphogensides, e.g. Tego-Betain 27 of Goldtschmit
AG, and fatty acid amido alkyl dimethyl aminoxide, e.g. aminoxide
WS 25 of Goldtschmit AG. These emulsifiers particularly promote the
emulsification of the compound of category 3 in the waterglass
component and hence also promote complete mixing of all the
components. The emulsifiers are generally added in quantities of up
to about 15% by weight, based on the mixture of polyisocyanate and
waterglass solution.
5. Thixotropic agents such as powdered asbestos or other surface
active additives alone or mixed with the emulsifiers mentioned
under category 4 . These thixotropic agents are preferably used
when mixtures of waterglass solution and the compounds mentioned
under category 3 are used. They also make it possible for emulsions
to remain stable for a considerable period so that two-component
systems comprising a package of waterglass solution and additives
or categories 1 to 4 and a package of polyisocyanates can be
handled at the site of consolidation. The thixotropic agents are
generally added in quantities of up to about 5% by weight, based on
the mixture of polyisocyanate and waterglass solution.
6. Foam stablizers, e.g. the organo-polysiloxanes known from
polyurethane chemistry.
Any of the above-mentioned additives may be added either alone or
in combination with each other either to the mixture or to the
components before they are mixed.
Multi-chamber cartridges containing the polyisocyanate, the
waterglass solution and possibly additives of categories 1 to 6 in
separate containers may also be introduced into the above-mentioned
boreholes. After mechanical destruction of the cartridges and
mixing of the liquid contents, e.g. by means of a rotating wooden
or metal rod or an anchor blade stirrer, the hardening foaming
mixture enters under its own foaming pressure into the formations
which are to be consolidated and sealed off and at the same time
also completely fills the bore-hole.
A summary of examples of mixtures which may be used and of the
practical application of the process is given in the following
Tables and Examples.
The various entries have the following meaning:
MDI: a polyisocyanate obtained by phosgenating a formaldehyde
aniline condensate and containing more than 50% of
diisocyanatodiphenyl methane and having an isocyanate content of
31% and a viscosity of 95 mPas at 25.degree. C.
Accelerator: Dibutyl tin dilaurate.
Polyol 1: a polyether polyol prepared from trimethylol propane and
propylene oxide and having an OH number of 370 and a viscosity of
700 mPas at 25.degree. C.
Polyol 2: a polyether polyol prepared from 1,2-propylene glycol and
propylene oxide and having an OH number of 59 and a viscosity of
410 mPas at 25.degree. C.
Emulsifier: a commercial alkyl phenol polyglycol ether (akyporox NP
105, Chemy, Emmerich).
Powdered Asbestos: a commercial product of Crace (Silodex 24).
Stabilizer: a commercial polyether polysiloxane stabilizer
(Stabilizer SJ, Bayer AG).
TABLE ______________________________________ Ratio by Weight
Waterglass: Molar Ratio Component A Component B Isocyanate
SiO.sub.2 :Na.sub.2 O ______________________________________ (1.)
80 g Waterglass 44% 90.4 g MDI 80:90 2:1 20 g Polyol 1 (2.) 40 g
Waterglass 44% 60 g MDI 40:60 2:1 10 g Polyol 1 0.9 g Accelerator
10 g Blowing Agent (3.) 80 g Waterglass 44% 75 g MDI 80:75 0.5:1 20
g Polyol 1 0.6 g Accelerator 0.5 g Stabilizer (4.) 75 g Waterglass
44% 25 g MDI 75:25 2:1 25 g Polyol 1 1.6 g Accelerator (5.) 80 g
Waterglass 50% 85 g MDI 80:36 2:1 15 g Polyol 1 5 g Polyol 2 2 g
Accelerator (6.) 50 g Waterglass 28% 40 g MDI 50:40 4:1 30 g Polyol
1 2 g Accelerator (7.) 25 g Waterglass 44% 75 g MDI 25:75 2:1 6.25
g Polyol 1 (8.) 50 g Waterglass 28% 50 g MDI 50:50 2:1 40 g Polyol
1 10 g Polyol 2 0.5 g Accelerator (9.) 80 g Waterglass 44% 72 g MDI
80:72 1:1 20 g Polyol 1 10 g Polyol 2 1 g Accelerator (10.) 90 g
Waterglass 44% 90 g MDI 90:90 2:1 10 g Polyol 1 30 g Blowing Agent
0.6 g Accelerator (11.) 80 g Waterglass 44% 51 g MDI 80:51 2:1 20 g
Polyol 1 0.3 g Accelerator 1.0 g Emulsifier 1.0 g Powdered Asbestos
(12.) 80 g Waterglass 44% 90 g MDI 80:90 2:1 15 g Polyol 1 5 g
Polyol 2 0.3 g Accelerator 1.0 g Emulsifier 1.0 g Powdered Asbestos
1.0 g Stabilizer ______________________________________
The waterglass used in the following Examples was a 44% by weight
aqueous solution of a sodium silicate (SiO.sub.2 :Na.sub.2
O=2:1).
EXAMPLES
Example 1
In a seam of 4 m average thickness and 0 to 10 gon dip the coal
face sloped off by up to 3.5 m. This resulted in roof fall of up to
7 m height and an over a length of 30 m. In 7 m spacing boreholes
of 4.5 m length and 45 mm dia. were drilled into the coal face.
The consolidating agent used consisted of:
Component A: waterglass
Component B: MDI.
Components A and B used in a ratio by weight of 1:1 were forced
under pressure into the bore-holes through a bore-hole seal by way
of a two-component mixing and pressurizing device so that 120 kg of
the mixture of components A and B entered each bore-hole.
Five hours later the consolidated zone was worked by shearer
loader. It was found that the surfaces of the gaps and crack in the
coal were glued together and a satisfactory consolidating effect
had been obtained. The coal face now sloped only slightly and
normal production could be continued.
Example 2
In the same coal face where tests described under example 1 were
run, consolidation work was continued in the trouble zone, however,
a polyol was added to the consolidation agent. The agent consisted
of the following components:
Component A:
mixture of 80 parts by weight of waterglass,
20 parts by weight of polyol 1 and
0.3 parts by weight of accelerator.
Component A was prepared from the above constituents by mixing with
the aid of a mechanical stirrer immediately before injection. The
emulsion obtained in this manner remained stable for several
hours.
Component B: MDI.
The coal face was consolidated as in Example 1. Components A and B
were used in a ratio by weight of 1.3:1.
The consolidating effect was complete. Sloping of the coal face was
completely eliminated.
Example 3
When working is 1.3 m thick seam inclined by 0 to 59 gon, the
gateroad side had to be consolidated. The roof consisted of solid
laminated clay, and the floor of sandstone. The roof in the face
ends showed signs of strong disaggregation over a length of 1.5 to
2 m, measured in direction of the dip. Fissures of up to 2 cm width
were stated. For consolidation, holes of 2.5 m depth and 45 cm dia.
were drilled 60 cm above the seam. The spacing of the boreholes
along the gateroad side was of 2.5 to 3 m. In a first phase four
boreholes were drilled.
The following consolidating agent was used:
Component A:
mixture of 90 parts by weight waterglass,
10 parts by weight polyol 2 and
1 part by weight accelerator.
Component B: MDI.
90 kg of the mixture of A and B (ratio by weight 1.5:1) were
introduced into the first bore-hole through a pressurizing device.
260 kg were forced into the second bore-hole, 350 kg into the third
and 129 kg into the fourth. The consolidation achieved was so
satisfactory that no breaks occurred in the face end zone. Samples
of rock found in the break showed that cracks and fissures in the
rock had been completely filled and perfectly sealed with the
hardened foam of components A and B.
Example 4
in a retreat face the face-end zone had to be consolidated in an
area up to 15 m ahead of the coal face by polyurethane. Since in
this area the rock strata were very wet and since the gaps and
fissures were filled with water, no sufficient consolidation effect
could be reached with a known polyurethane system. Boreholes of 5 m
length and rising at a 10.degree. angle were drilled into the roof
5 m ahead of the coal face. By these boreholes a total of 1000 kg
of the following blend were introduced.
Component A:
mixture of 80 parts by weight of waterglass,
10 parts by weight polyol 1,
10 parts by weight polyol 2,
5 parts by weight emulsifier,
1 part by weight accelerator,
1 part by weight powdered asbestos.
Component B: MDI.
The ratio by weight of components A to B was 1:1.2.
On passing through the consolidated trouble zone in the tunnel, it
was found that the roof was completely free from the breaks which
occurred in the non-consolidated zone.
Example 5
When the earth was dug out at a building site for constructing an
underground railway, ground water and quicksand were flushed out of
a gap (15 meters in height, 0.7 meter in width) into the tunnel
space. Attempts to consolidate the quicksand by the injection of
cement or waterglass into the walls produced no results. The
following mixture of waterglass and polyisocyanate was then
introduced through injection lances placed in the quicksand:
Component A:
mixture of 80 parts by weight of waterglass,
1 part by weight of accelerator.
Component B: reaction product of 90 parts by weight of MDI and 10
parts by weight of polypropylene glycol with hydroxyl number
56.
The ratio by weight of components A and B was 1:1.
A total of 100 kg of this mixture was injected into the slit
through the lance. The quicksand was found to be consolidated after
only 15 minutes. Another injection lance placed below the first
point of injection was introduced into the quicksand to a depth of
1300 mm. 70 kg of the mixture of components A and b were forced in
through this lance at a pressure of 50 bar. This additional
injection made it possible for the wall in the zone consolidated by
the injection to be sealed off against water and quicksand. Samples
of the consolidated quicksand were found to have a strength of
about 12 kp/cm.sup.2.
Example 6
In a seam with an average thickness of 2.80 m and an inclination of
5 gon the coal face sloped off by 3.5 m over a length of 40 m,
measured from the supply gate. This caused roof fall which strongly
affected production of the coal face. The resulting cavities had to
be supported with wooden props. The face in these zones had to be
advanced in handwork.
Bore-holes 50 mm in diameter and placed at a dip of ca. 10 gon were
sunk into the coal face in the critical zone at intervals of 1.5
meters and about 0.5 meters below the roof. 6 two-chamber
cartridges of polyethylene were inserted into each bore-hole. The
inner chamber of the cartridge contained the polyisocyanate while
the outer chamber contained a component of the following
composition:
90 g waterglass,
10 g polyol 1,
0.6 g accelerator, dibutyl tin dilaurate.
The cartridge contained the two components in a proportion by
weight of 1:1. The cartridges were destroyed inside the bore-holes
by means of rectangular wooden nails having an edge of 32 mm. The
components were throughly mixed by rotating the wooden nails, and
the bore-holes were then sealed with a plug. When the face was
mined 21/2 hours later, it was found that sloping of the coal face
could be prevented as a result of the consolidation.
Example 7
The cartridge used was a glass tube having a length of 60 cm, an
internal diameter of 2.6 cm and a wall thickness of 1 mm. This tube
was filled with 200 g of the following mixture:
160 g waterglass,
40 g polyol 1.
This tube contained another sealed glass tube having a length of 59
cm, an internal diameter of 1.6 cm and a wall thickness of 1 mm as
inner cartridge. This cartridge was filled with 102 g of
polyisocyanate mixture of the diphenyl methane series having a
viscosity of 100 mPas/25.degree. C. and an isocyanate content of
32% by weight.
The cartridge sealed with a plastics bung was introduced into a
bore-hole 30 mm in diameter. An anchor rod 24 mm in diameter was
pushed into the bore-hole and rotated at 350 revs. per min. The
cartridge was thereby destroyed and the components intimately
mixed. Bending was achieved over a length of 110 cm. The anchor rod
was pulled after 30 minutes. A pull of 24 tons was necessary to
remove the rod from the bore-hole.
Although the invention has been described in detail for the purpose
of illustration, it is to be understood that such detail is solely
for that purpose and that variations can be made therein by those
skilled in the art without departing from the spirit and scope of
the invention except as it may be limited by the claims.
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