U.S. patent application number 15/576114 was filed with the patent office on 2018-12-06 for coal dust treatment methods and compositions.
This patent application is currently assigned to General Electric Company. The applicant listed for this patent is General Electric Company. Invention is credited to Anilkumar Lokare, Chaitra M.N., Michael T. Raab, Seethalakshmi Suresh.
Application Number | 20180346834 15/576114 |
Document ID | / |
Family ID | 56322273 |
Filed Date | 2018-12-06 |
United States Patent
Application |
20180346834 |
Kind Code |
A1 |
Raab; Michael T. ; et
al. |
December 6, 2018 |
COAL DUST TREATMENT METHODS AND COMPOSITIONS
Abstract
Methods and compositions for treating coal are provided. A
nitroxyl radical compound is added to the coal in order to inhibit
coal autooxidation. Additionally, the nitroxyl radical compound can
be conjointly used with conventional dust control agents, in order
to suppress fugitive coal dust dissemination. In those cases in
which foamed treatment is desired to treat coal dust, the nitroxyl
radical compound can be conjointly used in the foamable
compositions, along with a variety of foam building surfactants
such as the amphoteric, nonionic and anionic surfactants.
Inventors: |
Raab; Michael T.;
(Langhorne, PA) ; Suresh; Seethalakshmi;
(Bangalore, IN) ; Lokare; Anilkumar; (Bangalore,
IN) ; M.N.; Chaitra; (Bangalore, IN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Assignee: |
General Electric Company
Schenectady
NY
|
Family ID: |
56322273 |
Appl. No.: |
15/576114 |
Filed: |
April 27, 2016 |
PCT Filed: |
April 27, 2016 |
PCT NO: |
PCT/US16/29519 |
371 Date: |
November 21, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10L 5/32 20130101; C10L
2230/081 20130101; C10L 2230/14 20130101; C10L 2200/04 20130101;
C10L 5/04 20130101; C10L 5/24 20130101; C10L 2250/04 20130101 |
International
Class: |
C10L 5/24 20060101
C10L005/24; C10L 5/04 20060101 C10L005/04; C10L 5/32 20060101
C10L005/32 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 2015 |
IN |
2615/CHE/2015 |
Claims
1. A method of treating coal comprising adding a nitroxyl radical
compound (NRC) to said coal.
2. The method of claim 1, wherein the NRC has the following
structure: ##STR00002## wherein R.sub.2, R.sub.3, R.sub.8, R.sub.9
are each independently of one another substituted or un-substituted
C.sub.1-C.sub.18 alkyl, C.sub.2-C.sub.18 alkenyl, or
C.sub.2-C.sub.18 alkynyl; or R.sub.2 and R.sub.3 and/or R.sub.8 and
R.sub.9 together form, with the linking carbon, a C.sub.3-C.sub.12
cycloalkyl radical; and R.sub.4, R.sub.5, R.sub.6, R.sub.7 are each
independently of one another hydrogen, substituted or
un-substituted C.sub.1-C.sub.18 alkyl, C.sub.2-C.sub.18 alkenyl, or
C.sub.2-C.sub.18 alkynyl; X is --O--, --C(O)--, .dbd.O,
--NR.sub.10-- or --NR.sub.10--C(O)--; wherein R.sub.10 is hydrogen,
phenyl, or C.sub.1-C.sub.18 alkyl; and wherein R.sub.1 is hydrogen,
phenyl, substituted or un-substituted C.sub.1-C.sub.18 alkyl,
C.sub.2-C.sub.18 alkenyl, or C.sub.2-C.sub.18 alkynyl.
3. A method as recited in claim 1 wherein said NRC is added to said
coal in an amount of about 0.001 to 10 lbs, per ton of coal.
4. A method as recited in claim 1 wherein said NRC is selected from
the group consisting of dialkyl nitroxyl radicals,
1-oxyl-2,2,6,6-tetraalkylpiperidine compounds,
1-oxyl-2,2,6,6-tetramethylpiperidine,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-ol (4-HT),
1-oxyl-2,2,6,6-tetramethylpiperidin-4-one,
1-oxyl-2,2,6,6-tetramethylpiperidine-4-yl acetate,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-2-ethylhexanoate,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl stearate,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butylbenzoate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)succinate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipate,
bis(1-oxyl-2,2,6,6-tetramethypiperidin-4-yl)sebacate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)n-butylmalonate,
bis(1-oxyl-2,2,6,6-tetramethylpiperadin-4-yl)phthalate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)isophthalate,
bis(1-oxyl-2,2,6,6-tetramethyl piperidinyl-4-yl)terephthalate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)hexahydroterephthalate,
N,N'-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipamide,
N-1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-dodecyl succinimide,
1-oxyl-4-methoxy-2,2,6,6-tetramethylpiperidine,
1-oxyl-4-amino-2,2,6,6-tetramethylpiperidine,
4-butoxy-2,2,6,6-tetramethylpiperidine and
1-oxyl-4-acetamino-2,2,6,6-tetramethyl piperidine and derivatives
thereof.
5. A method as recited in claim 4 wherein said NRC is
1-oxyl-2,2,6,6-tetramethylpiperdin-4-ol (4HT).
6. A method as recited in claim 1 wherein said method further
comprises adding a foaming agent selected from amphoteric, nonionic
and anionic surfactants to said coal.
7. A method as recited in claim 6 wherein said foaming agent
comprises an anionic surfactant.
8. A method as recited in claim 7 wherein said anionic surfactant
comprises an alkane sulfonate or an alkenyl sulfonate.
9. A method as recited in claim 1 wherein said method further
comprises adding a dust control agent (DCA) to said coal.
10. A method as recited in claim 9 wherein said DCA comprises a
polymer.
11. A method as recited in claim 10 wherein said polymer is a
member selected from the group consisting of i) polymers containing
two or more of epichlorohydrin, polyalkylene polyamine, and adipic
acid monomers, ii) aminoalkylated polyacrylamides, and iii)
quaternary ammonium polymers or copolymers.
12. A method as recited in claim 11 wherein said i) polymers
containing two or more of epichlorohydrin, polyalkylene polyamine,
and adipic acid monomers comprise diethyltriamine, adipic acid, and
epichlorohydrin monomers, wherein said ii) aminoalkylated
polyacrylamides comprise aminomethylated polyacrylamides, and
wherein the iii) quaternary ammonium polymers or copolymers
comprise a reaction product of quaternaryamine, dimethylamine, and
epicholohydrin.
13. A composition comprising a) a nitroxyl radical composition
(NRC) and one or more of b) dust control agent and c) foaming
agent, wherein if a) and b) are present, for every 1-5 parts of a),
there are 1-100 parts of b), and wherein if a) and c) are present,
for every 1-5 parts of a) there are 0.01-10 parts of c), and
wherein if all three of a) and b) and c) are present, for every 1-5
parts of a) there are 1-100 parts of b) and 0.01-10 parts of
c).
14. A composition as recited in claim 13, wherein the NRC has the
following structure: ##STR00003## wherein R.sub.2, R.sub.3,
R.sub.8, R.sub.9 are each independently of one another substituted
or un-substituted C.sub.1-C.sub.18 alkyl, C.sub.2-C.sub.18 alkenyl,
or C.sub.2-C.sub.18 alkynyl; or R.sub.2 and R.sub.3 and/or R.sub.8
and R.sub.9 together form, with the linking carbon, a
C.sub.3-C.sub.12 cycloalkyl radical; and R.sub.4, R.sub.5, R.sub.6,
R.sub.7 are each independently of one another hydrogen, substituted
or un-substituted C.sub.1-C.sub.18 alkyl, C.sub.2-C.sub.18 alkenyl,
or C.sub.2-C.sub.18 alkynyl; X is --O--, --O--C(O)--, .dbd.O,
--NR.sub.10-- or --NR.sub.10--C(O)--; wherein R.sub.10 is hydrogen,
phenyl, or C.sub.1-C.sub.18 alkyl; and wherein R.sub.1 is hydrogen,
phenyl, substituted or un-substituted C.sub.1-C.sub.18 alkyl,
C.sub.2-C.sub.18 alkenyl, or C.sub.2-C.sub.18 alkynyl.
15. A composition as recited in claim 13 wherein said a) NRC is
selected from the group consisting of dialkyl nitroxyl radicals,
1-oxyl-2,2,6,6-tetraalkylpiperidine compounds,
1-oxyl-2,2,6,6-tetramethylpiperidine,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-ol (4-HT),
1-oxyl-2,2,6,6-tetramethylpiperidin-4-one,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl acetate,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-2-ethylhexanoate,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl stearate,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butylbenzoate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)succinate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipate,
bis(1-oxyl-2,2,6,6-tetramethypiperidin-4-yl)sebacate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)n-butylmalonate,
bis(1-oxyl-2,2,6,6-tetramethylpiperadin-4-yl)phthalate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)isophthalate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)terephthalate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)hexahydroterephthalate,
N,N'-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipamide,
N-1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-dodecyl succinimide,
1-oxyl-4-methoxy-2,2,6,6-tetramethylpiperidine,
1-oxyl-4-amino-2,2,6,6-tetramethylpiperidine,
4-butoxy-2,2,6,6-tetramethylpiperidine and
1-oxyl-4-acetamino-2,2,6,6-tetramethylpiperidine and derivatives
thereof.
16. A composition as recited in claim 15 wherein said NRC is
1-oxyl-2,2,6,6-tetramethypiperidin-4-ol (4HT).
17. A composition as recited in claim 13, wherein the foaming agent
is selected from amphoteric, nonionic and anionic surfactants.
18. A composition as recited in claim 17, wherein the foaming agent
comprises an anionic surfactant.
19. A composition as recited in claim 18, wherein the anionic
surfactant comprises an alkane sulfonate or an alkenyl
sulfonate.
20. A composition as recited in claim 13, wherein said dust control
agent comprises a polymer.
21. A composition as recited in claim 20, wherein said polymer is a
member selected from the group consisting of i) polymers containing
two or more of epichlorohydrin, polyalkylene polyamine, and adipic
acid monomers, ii) aminoalkylated polyacrylamides, and iii)
quaternary ammonium polymers or copolymers.
22. A composition as recited in claim 21, wherein said i) polymers
containing two or more of epichlorohydrin, polyalkylene polyamine,
and adipic acid monomers comprise diethyltriamine, adipic acid, and
epichlorohydrin monomers, wherein said ii) aminoalkylated
polyacrylamides comprise aminomethylated polyacrylamides, and
wherein the iii) quaternary ammonium polymers or copolymers
comprise a reaction product of quaternaryamine, dimethylamine, and
epicholohydrin.
23. A composition comprising coal and a) a nitroxyl radical
composition (NRC) and one or more of b) dust control agent and c)
foaming agent, wherein if a) and b) are present, for every 1-5
parts of a), there are 1-100 parts of b), and wherein if a) and c)
are present, for every 1-5 parts of a) there are 0.01-10 parts of
c), and wherein if all three of a) and b) and c) are present, for
every 1-5 parts of a) there are 1-100 parts of b) and 0.01-10 parts
of c), and wherein a) is present in an amount of about 0.001 to 10
lbs per ton of the coal.
24. A method of treating coal comprising adding a quaternary
ammonium compound to said coal.
25. The method of claim 24 wherein the quaternary ammonium compound
is quaternaryamine/dimethylamine/epichlorohydrin.
26. A method of treating coal comprising adding an amine
functionalized tannin to said coal.
27. The method of claim 26, wherein the amine functionalized tannin
is tannin/monoethanolamine/formaldehyde.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority benefit of Indian
Provisional Patent Application No. 2615/CHE/2015 filed May 25,
2015.
FIELD OF THE INVENTION
[0002] The present invention pertains to methods for treating coal
and coal piles to inhibit fugitive coal dust dissemination, and
coal auto-oxidation. Additionally, stability of foam used to apply
dust control and auto-oxidation treatments is also improved.
BACKGROUND
[0003] Coal is a carbonaceous solid fossil fuel. It is extracted
(mined) by surface or underground methods. Coal that is not yet
mined, but is in the ground, that may or may not be exposed to the
outside conditions is referred to as in-situ coal. Mined coal is
usually crushed to a smaller size for transportation, handling and
storage. The usual size for this crushed coal is less than eight
inches (less than 200 mm). This invention treats both in-situ coal
and extracted (mined) coal during transportation, handling and
storage. During transportation, handling and storage, mined coal
can generate coal dust. Coal dust dissemination poses safety,
health and environmental concerns. Coal dust suppression is
desirable to minimize coal dust dissemination that may occur during
coal pile storage or transit. Airborne fugitive coal dust
particulates can lead to black lung disease and other
illnesses.
[0004] Additionally, when coal is exposed to air, it slowly
oxidizes to form CO.sub.2 and heat. Oxidation is accelerated in the
presence of moisture and elevated temperature. Oxidation is a
detrimental process since it reduces the caloric heating value of
coal and can cause spontaneous combustion, or coal self-ignition.
In some instances where coal self-ignition occurs in the presence
of airborne coal dust, coal dust explosions can also occur.
[0005] Coal has traditionally been stored in piles to reduce the
intrusion of air and moisture and to thereby mitigate the oxidation
process. Piling does not halt coal oxidation but is merely an
attempt to slow the oxidation rate. The ideal coal pile is large
enough to reduce the surface to volume ratio of the coal exposed to
air, yet small enough that heat generated within the coal pile is
dissipated into the surrounding environment. Unfortunately, in
large coal handling facilities, such as those existing at coal
fueled power plants, the large quantity of coal utilized makes
ideal conditions difficult to achieve and incidents of coal
self-ignition resulting from coal oxidation are common occurrences.
Coal fires and coal dust explosions pose serious dangers to
personnel and are costly in terms of damaged equipment and consumed
coal.
[0006] In many cases, coal may be treated with aqueous based foam
in order to suppress dissemination of the fine coal dust particles,
or to aid in the application of a dust control binder. These foams
may be formed and applied as set forth, for example, in U.S. Pat.
No. 4,400,220 (Cole). Foaming agents such as certain amphoteric
surfactants, anionic surfactants and nonionic surfactants may be
employed to aid in foam building and dust suppression. Stability of
the foam is an important characteristic for maximum surface area
contact with the coal surfaces during application.
[0007] Overall, in regard to coal storage and transit problems such
as those noted above, a versatile product is desired to treat these
problems, and desirably such a product would also enhance foam life
stability in those situations in which foamed applications are
utilized.
SUMMARY OF THE INVENTION
[0008] In one embodiment, a method of treating coal is provided
wherein a nitroxyl radical compound (NRC), an amine functionalized
tannin or a quaternary ammonium compound is added to the coal.
Typically, the NRC is added to the coal in an amount of about 0.001
to 10 pounds per ton of coal with an addition rate of about 0.005-1
pound of the NRC per ton of coal also being noted as exemplary.
[0009] In some cases it is desirable to provide foamed treatments
to the coal and, in this regard, a foaming agent such as those
selected from the group of amphoteric, nonionic and anionic
surfactants can be used. In these cases the NRC can be conjointly
used with the surfactant to enhance foam stability and durability.
In one embodiment, the foaming agents include anionic surfactants
and those comprising a long chain C.sub.11-C.sub.18 alkenyl
sulfonate salt such as C.sub.11-C.sub.16 alkenyl sodium
sulfonate.
[0010] In other embodiments, the NRC can be employed conjointly
with a dust control agent (DCA) and applied to the coal. The DCA
may, for example, comprise a variety of different polymers. In one
embodiment, the DCA comprises polymers chosen from i)
epichlorohydrin (EPI)/polyalkylene polyamine/adipic acid
terpolymers; ii) aminoalkylated polyacrylamides, and iii)
quaternary ammonium polymers and copolymers.
[0011] In most cases, the NRC will be applied to the coal in the
form of an aqueous solution or dispersion. Aqueous compositions
comprised of a) a nitroxyl radical (NRC) and one or more of b) dust
control agent and c) foaming agent may be utilized where if a) and
b) are present, for every 1-5 parts of a), there are 1-100 parts of
b). If a) and c) are present, for every 1-5 parts of a) there are
0.01-10 parts of c). If all three of a) and b) and c) are present,
for every 1-5 parts of a) there are 1-100 parts of b) and 0.01-10
parts of c). In another embodiment, a composition is comprised of
the components described above where if a) and b) are present, for
every 1 parts of a), there are 1-20 parts of b). If a) and c) are
present, for every 1 part of a) there are 0.15-2 parts of c). If
all three of a) and b) and c) are present, for every 1 part of a)
there are 1-20 parts of b) and 0.15-2 parts of c).
DETAILED DESCRIPTION
[0012] In one exemplary embodiment of the invention, a nitroxyl
radical compound (NRC) is provided to treat coal surfaces, such as
coal piles, to retard coal auto-oxidation, self-heating and
spontaneous combustion. In other embodiments, the nitroxyl radical
compound is used conjointly with a DCA such as a polymer to improve
the dust control efficacy in its ability to agglomerate fine
particles and inhibit dust dissemination.
[0013] In another aspect of the invention in which foamed
application to coal is desired, the NRC is added to the DCA along
with an anionic foaming agent. The NRC and foaming agent can be
added without DCA. The use of NRC with the foaming agent improves
foam quality and stability.
[0014] In one embodiment, the NRC can have the following
structure:
##STR00001##
where R.sub.2, R.sub.3, R.sub.8, R.sub.9 are each independently of
one another substituted or un-substituted C.sub.1-C.sub.18 alkyl,
C.sub.2-C.sub.18 alkenyl, or C.sub.2-C.sub.18 alkynyl; or R.sub.2
and R.sub.3 and/or R.sub.8 and R.sub.9 together form with the
linking carbon a C.sub.3-C.sub.12 cycloalkyl radical R.sub.4,
R.sub.5, R.sub.6, R.sub.7 are each independently of one another
hydrogen, substituted or un-substituted C.sub.1-C.sub.18 alkyl,
C.sub.2-C.sub.18 alkenyl, or C.sub.2-C.sub.18 alkynyl; X is --O--,
--O--C(O)--, .dbd.O, --NR.sub.10-- or --NR.sub.10--C(O)--; R.sub.10
is hydrogen, phenyl, or substituted or unsubstituted
C.sub.1-C.sub.18 alkyl R.sub.1 is hydrogen, phenyl, substituted or
un-substituted C.sub.1-C.sub.18 alkyl, C.sub.2-C.sub.18 alkenyl, or
C.sub.2-C.sub.18 alkynyl.
[0015] In another embodiment, R.sub.2, R.sub.3, R.sub.8, R.sub.9
are each independently of one another substituted or un-substituted
C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6
alkynyl; R.sub.2 and R.sub.3 and/or R.sub.8 and R.sub.9 together
form with the linking carbon a C.sub.3-C.sub.12 cycloalkyl radical;
R.sub.4, R.sub.5, R.sub.6, R.sub.7 are each independently of one
another hydrogen, substituted or un-substituted C.sub.1-C.sub.6
alkyl, C.sub.2-C.sub.6 alkenyl, or C.sub.2-C.sub.6 alkynyl; X is
--O--, --O--C(O)--, .dbd.O, --NR.sub.10-- or
--NR.sub.10--C(O)--;
R.sub.10 is hydrogen, phenyl, or substituted or unsubstituted
C.sub.1-C.sub.6 alkyl, R.sub.1 is hydrogen, substituted or
un-substituted C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, or
C.sub.2-C.sub.6 alkynyl.
[0016] Exemplary nitroxyl radical compounds (NRC) include
derivations of dialkyl nitroxyl radicals and
1-oxyl-2,2,6,6-tetraalkylpiperidine compounds such as
1-oxyl-2,2,6,6-tetramethylpiperidine,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-ol (4-HT),
1-oxyl-2,2,6,6-tetramethylpiperidin-4-one,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl acetate,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-2-ethylhexanoate,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl stearate,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate,
1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butylbenzoate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)succinate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipate,
bis(1-oxyl-2,2,6,6-tetramethypiperidin-4-yl)sebacate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)n-butylmalonate,
bis(1-oxyl-2,2,6,6-tetramethylpiperadin-4-yl)phthalate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidinyl-4-yl)isophthalate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidinyl-4-yl)terephthalate,
bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)hexahydroterephthalate,
N,N'-bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipamide,
N-1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-dodecyl succinimide,
1-oxyl-4-methoxy-2,2,6,6-tetramethylpiperidine,
1-oxyl-4-amino-2,2,6,6-tetramethylpiperidine,
4-butoxy-2,2,6,6-tetramethylpiperidine and
1-oxyl-4-acetamino-2,2,6,6-tetramethylpiperidine. In one
embodiment, the nitroxyl radical compound is 4HT.
[0017] In one aspect of the invention, in those situations in which
dust control dissemination is desired, a polymer dust control agent
(DCA) can be used conjointly with the NRC. These polymer dust
control agents are well known and are discussed for example in U.S.
Pat. No. 5,256,444, which is incorporated by reference herein in
its entirety. Exemplary polymer DCAs are i) polymers having at
least two of the following monomers: epichlorohydrin (epi),
polyalkylene polyamine, and adipic acid; ii) polymers including
aminoalkylated polyacrylamides; and iii) quaternary ammonium
polymers and copolymers. In another embodiment, the DCA polymer has
three of the following monomers: epichlorohydrin (epi),
polyalkylene polyamine, and adipic acid; ii) polymers including
aminoalkylated polyacrylamides; and iii) quaternary ammonium
polymers and copolymers. Exemplary members of these monomers in i)
above are diethyltriamine, adipic acid and epichlorohydrin (epi),
and other examples of DCAs can include ii) aminomethylated
polyacrylamides, and iii) reaction products of quaternaryamine,
dimethylamine, and epi. In one embodiment, molecular weights for
these polymers are 100,000 to 5,000,000. In another embodiment,
molecular weights for these polymers are 300,000 to 2,500,000.
[0018] Typically, from about 0.001-10 lbs of the nitroxyl radical
compound is added to the coal based upon 1 ton of coal. In other
embodiments, the NRC is added in an amount of 0.002-5 lbs per ton
of coal. In other embodiments, the NRC is added in an amount of
0.0035-2.5 lbs per ton of coal. In other embodiments, the NRC is
added in an amount of 0.005-1.0 lbs per ton of coal.
[0019] In these cases in which foamed application to coal is used,
the NRC can be conjointly used with known foaming agents such as
nonionic, such as alkyl polyglucoside, amphoteric, such as ether
amines, or anionic, such as long chain alkenyl, surfactants. In one
embodiment, the foaming agent is an anionic surfactant with long
alkenyl (C.sub.11-C.sub.18) chain. One such anionic surfactant is a
sodium olefin (C.sub.14-C.sub.16) sulfonate.
[0020] In those situations in which the NRC is conjointly used with
a DCA and/or a foaming agent, the composition can include a) and
one or more of b) and c). [0021] a)=NRC [0022] b)=DCA [0023]
c)=Foaming Agent
[0024] In one embodiment, if a) and b) are present, for every 1-5
parts of a), there are 1-100 parts of b). If a) and c) are present,
for every 1-5 parts of a) there are 0.01-10 parts of c). If all
three of a) and b) and c) are present, for every 1-5 parts of a)
there are 1-100 parts of b) and 0.01-10 parts of c).
[0025] In another embodiment, if a) and b) are present, for every
1-5 parts of a), there are 1-75 parts of b). If a) and c) are
present, for every 1-5 parts of a) there are 0.075-7.5 parts of c).
If all three of a) and b) and c) are present, for every 1-5 parts
of a) there are 1-75 parts of b) and 0.075-7.5 parts of c).
[0026] In yet another embodiment, if a) and b) are present, for
every 1-5 parts of a), there are 1-50 parts of b). If a) and c) are
present, for every 1-5 parts of a) there are 0.1-5 parts of c). If
all three of a) and b) and c) are present, for every 1-5 parts of
a) there are 1-50 parts of b) and 0.1-5 parts of c).
[0027] In one embodiment, if a) and b) are present, for every 1
parts of a), there are 1-20 parts of b). If a) and c) are present,
for every 1 part of a) there are 0.15-2 parts of c). If all three
of a) and b) and c) are present, for every 1 part of a) there are
1-20 parts of b) and 0.15-2 parts of c).
[0028] In one embodiment, the aqueous based compositions has the
above a):b):c) components therein, with the remainder of the
composition including water and possibly other minor
components.
[0029] The NRC and other components can be applied to coal in-situ
or that has been extracted (mined), during transportation, handing
or storage, at the mine site and or any subsequent location such as
terminals, docks, storage yards, coal yards, power plants or other
coal utilizing facilities. Aqueous sprays are often used for
application to the coal. In one embodiment, the NRC is applied by
itself or in combination with or without a DCA applied as a foam.
For foamed applications, foaming agents such as those mentioned
above are used in combination with the NRC.
EXAMPLES
Coal Auto-Oxidation Inhibition
Example 1
[0030] In order to assess the efficacy of the materials in
inhibition of coal dust self-ignition, coal self-heating tests were
performed. This is an accelerated test method wherein a coal sample
is heated to a predetermined temperature with a known quantity and
flow of air being supplied. This method accelerates natural coal
oxidation and leads to the coal reaching a thermal runaway
state.
Coal Sample:
[0031] Coal crushed to -250 microns
Solutions and Application:
[0032] Chemistries are prepared at two different concentrations in
water, 0.5% and 2%. The chemistries are applied to the coal at a
rate so that the same amount of moisture (4%) is added to all coal
samples.
Measurements:
[0033] Temperature of the coal sample is measured and logged. Time
for the coal sample to reach thermal runaway (typically at 200 F)
is recorded. The delay in time to thermal runaway for a treated
coal sample versus blank and moisture only samples are used to
evaluate anti-oxidation efficacy.
Procedure:
[0034] A coal sample is weighed to 50 g. The desired chemistry (or
moisture blank) is applied to the coal dropwise. The coal is
thoroughly mixed with the solution using a stainless steel spatula.
The sample is mixed until homogenous, and then transferred to the
reaction vessel. The test apparatus consists of rectangular vessel
(reaction chamber) with 6 slots to place the reaction vessels and
is connected to an auto temperature logger. The reaction chamber
has a heater and is filled with silicone oil for heating. The
required temperature of oil bath is set and the reaction vessels
are placed in the chamber. The airflow is then started. The
reaction chamber heating begins and starts heating the coal
samples. Thermocouples are placed in the oil bath to measure the
set temperature of the oil bath and continuously log bath
temperature in the data acquisition system. Each reaction vessel is
provided with two thermocouples at different points and temperature
data is logged continuously. One blank coal sample and one moisture
blank sample are included as controls along with the treated
samples. Data is continuously logged until the coal has reached
thermal runway.
Results are shown in Table 1.
TABLE-US-00001 Time to Thermal Run Away Time to .DELTA. vs no
Chemical Dosage runaway treatment Treatment Level (min) (min) No
treatment N/A 170 n/a Moisture N/A 183.3 n/a addition only C1 0.5
225 55 C1 2.0 257 87 C2 0.5 190 20 C2 2.0 197 27 EX1 0.5 203 33 EX1
2.0 215 45 EX2 0.5 198 28 EX2 2.0 218 48 EX3 0.5 215 45 EX3 2.0 223
53 C1 = comparative = aqueous polymer, diethylaminetriamine/adipic
acid/epichlorohydrin terpolymer C2 = comparative = aqueous polymer,
aminomethylated polyacrylamide EX1 =
1-oxyl-2,2,6,6-tetramethylpiperidin-4-ol (4HT) EX2 =
quaternaryamine/dimethylamine/epichlorohydrin EX3 =
tannin/monoethanolamine/formaldehyde
[0035] The delay in time, compared to an untreated control, for
onset of thermal runaway is indicative of inhibition of
auto-oxidation. In this example, EX-1 performs at a level of
inhibition comparable to known auto-oxidation inhibition polymers,
which is surprising since traditional antioxidant products are
polymeric, and EX-1 is a monomer.
Example 2--Dust Control Improvement
Apparatus:
[0036] Dust Monitor--Lab scale dust monitor uses white light to
determine dust levels of materials dropped into the sampling
chamber.
Substrate:
[0037] Coal samples, mixture of size fractions to generate
sufficient dust to study.
Procedure:
[0038] Prepare solutions of various concentrations of each of the
products. Prepare untreated coal substrate samples with spinning
riffler to ensure uniform particle size distribution for each
sample. Apply products to the coal. Dry the samples at 140 F for 30
minutes. Cool at room temperature for 30 minutes. Pass samples
through the Dust Monitor and record dust values. The reported value
is Dust Area+Max, which is the area integrated under the curve for
the sample measured over 30 seconds added to the maximum dust level
recorded for the sample. Lower Dust Area+Max values are indicative
of superior dust control.
[0039] In these examples, EX-1, namely 4HT was added to coal
without any dust control agent, and in addition to a known dust
control agent, namely an aqueous aminomethylated polyacrylamide
(designated as "C2"). Dust control improvement is shown in
following Tables 2 and 3.
TABLE-US-00002 TABLE 2 Dust Area + Test C2 % 4HT % Max A 0.0 5.0
213.76 B 0.0 10.0 162.31 C 0.0 20.0 116.78 D 5.0 0.0 54.93 E 2.5
2.5 36.33 F (DI water only) 0.0 0.0 116.58
[0040] Table 2 shows that when 4HT alone is added to coal it has a
negative impact on dust generation relative to water. When 4HT is
added as an adjuvant to C2, a known polymer dust control agent
(DCA), it synergistically improves the DCA's dust reduction
performance.
TABLE-US-00003 TABLE 3 Dust Area + Test C2 % 4HT % Max A 2.50 0.10
36.45 B 2.50 0.25 48.05 C 2.50 0.50 36.20 D 2.50 1.00 34.10 E 2.50
1.50 33.40 F 2.50 2.00 36.00 G 2.50 2.50 40.60 H (control) 5.00
0.00 62.15
[0041] Table 3 shows that low dosages of 4HT added as an adjuvant
to C2, a known polymer dust control agent (DCA), synergistically
improves the DCA's dust reduction performance.
Example 3--Foam Stability
[0042] 4HT was added to a known foaming agent, "C4", an anionic
surfactant, sodium olefin (C.sub.14-C.sub.16) sulfonate to
determine its effect on foam stability.
Solutions:
[0043] 200 mL solutions at ambient temperature (72.degree. F.)
Apparatus:
[0044] Waring Commercial Blender (Model 7011G) marked with 50 mL
graduations
Measurements:
[0045] Maximum foam height (to nearest 25 mL) [0046] 1/2 life time
(in sec)--time for 100 mL of solution to drain back into liquid
phase
Procedure:
[0047] 200 mL of solution was poured into the blender. The blender
was turned on low speed for 30 seconds. The blender was then
allowed to sit until half of the sample (100 mL) returned back to
liquid state. The amount of time that passed until the liquid-foam
interface hit the 100 mL mark was recorded as "foam 1/2 life
time."
Results are shown in Tables 3 and 4
TABLE-US-00004 TABLE 3 Foam 1/2 life (min:sec) C4 + 4HT 0.75% + C4
+ C2 C4 % C4 only C4 + 4HT 1.5% C2 0.75% 0.75% 0.1 1:51 3:57 3:49
2:38 0.3 3:41 5:57 5:39 3:22 0.5 4:31 6:10 6:29 4:10 0.7 5:01 6:52
6:47 4:37 0.9 5:08 7:10 7:07 5:01 1.1 5:21 6:57 7:34 5:11
TABLE-US-00005 TABLE 4 Foam 1/2 life C4 % 4HT % (min:sec) 0 0.50
0:26 0 1.00 0:36 0 1.50 0:44 0 2.00 0:48 0 2.50 0:51 C2 = aqueous
polymer, aminomethylated polyacrylamide C4 = anionic surfactant,
sodium olefin (C.sub.14-C.sub.16) sulfonate
[0048] From Table 3 it can be seen that foam stability was improved
by addition of 4HT to C4, an anionic surfactant and to the
combination of C4 with C2. From Table 4, it can be seen the 4HT has
no significant foaming properties of its own. Surprisingly, the
combination of 4HT with C4 provided a synergistic effect with
regard to foam stabilization.
[0049] Additional tests were undertaken in waters of varying
hardness. These tests looked at soft (40 ppm as CaCO.sub.3), medium
(80 ppm Ca as CaCO.sub.3) and very hard (600 ppm Ca as CaCO.sub.3)
waters. Changes in hardness can affect stable foam generation. As
shown in Table 5, at all three of these hardness levels, the
combination of C4 (0.3.% or 0.5%) with 4HT (various concentrations)
improved foam stability.
TABLE-US-00006 TABLE 5 Foam 1/2 Life (min:sec) 40 80 600 C4 % 4HT %
ppm ppm ppm 0.3 0.0 3:59 4:05 2:19 0.3 0.5 4:35 4:38 3:49 0.3 1.0
5:26 5:50 5:01 0.3 1.5 5:24 6:21 5:16 0.5 0.0 4:36 4:47 3:02 0.5
0.5 5:16 5:32 4:28 0.5 1.0 6:14 6:29 5:36 0.5 1.5 6:07 6:56
5:55
* * * * *