AU2016266725B2

AU2016266725B2 - Coal dust treatment methods and compositions

Info

Publication number: AU2016266725B2
Application number: AU2016266725A
Authority: AU
Inventors: Anilkumar LOKARE; Chaitra M.N.; Michael T. Raab; Seethalakshmi Suresh
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2015-05-25
Filing date: 2016-04-27
Publication date: 2020-05-07
Anticipated expiration: 2036-04-27
Also published as: US20180346834A1; EP3303525A2; CN107835850A; KR20180012296A; JP2018515675A; CA2986900A1; WO2016191019A3; AU2016266725A1; WO2016191019A2

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.

Description

COAL DUST TREATMENT METHODS AND COMPOSITIONS

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 CO2 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

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PCT/US2016/029519 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. Patent 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 Cn-Cis alkenyl sulfonate salt such as Cu-Ci6 alkenyl sodium sulfonate.

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PCT/US2016/029519 [0010] In other embodiments, the NRC can be employed conjointly with a dust control agent (DC A) and applied to the coal. The DC A 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 0.152 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:

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where

R2, R3, Rs, R9 are each independently of one another substituted or un-substituted Ci Cis alkyl, C2 - Cis alkenyl, or C2 - Cis alkynyl; or

R2 and R3 and/or Rs and R9 together form with the linking carbon a C3 - C12 cycloalkyl radical

R4, Rs, Re, R7 are each independently of one another hydrogen, substituted or unsubstituted Ci - Cis alkyl, C2 - Cis alkenyl, or C2 - Cis alkynyl;

X is -0-, -O-C(O) -, =0, —NR10— or -NRio-C(O)

Rio is hydrogen, phenyl, or substituted or unsubstituted Ci - Cis alkyl

Ri is hydrogen, phenyl, substituted or un-substituted Ci - Cis alkyl, C2 - Cis alkenyl, or C2 - Cis alkynyl.

[0015] In another embodiment, R2, R3, Rs, R9 are each independently of one another substituted or un-substituted Ci - Ce alkyl, C2 - Ce alkenyl, or C2 - Ce alkynyl; R2 and R3 and/or Rs and R9 together form with the linking carbon a C3 - C12 cycloalkyl radical; R4, Rs, Re, R7 are each independently of one another hydrogen, substituted or un-substituted Ci - Ce alkyl, C2 - Ce alkenyl, or C2 - Ce alkynyl; X is -0-, -O-C(O) -, =0, —NR10— or -NRio-C(O) -;

Rio is hydrogen, phenyl, or substituted or unsubstituted Ci - Ce alkyl, Ri is hydrogen, substituted or un-substituted Ci - Ce alkyl, C2 - Ce alkenyl, or C2 - Ce alkynyl.

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PCT/US2016/029519 [0016] Exemplary nitroxyl radical compounds (NRC) include derivations of dialkyl nitroxyl radicals and l-oxyl-2,2,6,6-tetraalkylpiperidine compounds such as 1oxyl-2,2,6,6-tetramethylpiperidine, l-oxyl-2,2,6,6-tetramethylpiperidin-4-ol (4-HT), l-oxyl-2,2,6,6-tetramethylpiperidin-4-one, l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl acetate, l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl-2-ethylhexanoate, 1-oxyl-2,2,6,6tetramethylpiperidin-4-yl stearate, l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl benzoate, l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl 4-tert-butylbenzoate, bis(l-oxyl-2,2,6,6tetramethylpiperidin-4-yl)succinate, bis(l -oxyl-2,2,6,6-tetramethylpiperidin-4yl)adipate, bis(l-oxyl-2,2,6,6-tetramethypiperidin-4-yl)sebacate, bis(l-oxyl-2,2,6,6tetramethylpiperidin-4-yl)n-butylmalonate, bis(l-oxyl-2,2,6,6-tetramethylpiperadin-4yl)phthalate, bis(l-oxyl-2,2,6,6-tetramethylpiperidinyl-4-yl)isophthalate, bis(l-oxyl2,2,6,6-tetramethylpiperidinyl-4-yl)terephthalate, bis(l-oxyl-2,2,6,6tetramethylpiperidin-4-yl)hexahydroterephthalate, N,N’-bis(l-oxyl-2,2,6,6tetramethylpiperidin-4-yl)adipamide, N-l-oxyl-2,2,6,6-tetramethylpiperidin-4-yldodecyl succinimide, l-oxyl-4-methoxy-2,2,6,6-tetramethylpiperidine, l-oxyl-4amino-2,2,6,6-tetramethylpiperidine, 4-butoxy-2,2,6,6-tetramethylpiperidine and 1oxyl-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. Patent 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,

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PCT/US2016/029519 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 (Cn-Cis) chain. One such anionic surfactant is a sodium olefin (Cu-Cie) 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).

a) =NRC

b) = DCA

c) = Foaming Agent [0021] 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).

[0022] 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).

[0023] 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).

[0024] 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

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PCT/US2016/029519 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).

[0025] 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.

[0026] 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 [0027] Example 1 - 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:

[0028] Coal crushed to -250 microns

Solutions and application:

[0029] 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.

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Measurements:

[0030] Temperature of the coal sample is measured and logged. Time for the coal sample to reach thermal runaway (typically at 200F) 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:

[0031] A coal sample is weighed to 50g. 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.

Time to Thermal Run Away

Chemical Treatment	Dosage Level	Time to runaway (min)	A vs no treatment (min)
No treatment	N/A	170	n/a
Moisture addition only	N/A	183.3	n/a
Cl	0.5	225	55
Cl	2.0	257	87
C2	0.5	190	20
C2	2.0	197	27
EXI	0.5	203	33

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EXI	2.0	215	45
EX2	0.5	198	28
EX2	2.0	218	48
EX3	0.5	215	45
EX3	2.0	223	53

Cl = comparative = aqueous polymer, diethylaminetriamine/adipic acid/epichlorohydrin terpolymer

C2 = comparative = aqueous polymer, aminomethylated polyacrylamide

EXI = l-oxyl-2,2,6,6-tetramethylpiperidin-4-ol (4HT)

EX2 = quaternaryamine/dimethylamine/epichlorohydrin

EX3 = tannin/monoethanolamine/formaldehyde [0032] 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.

[0033] Example 2 - Dust Control Improvement

Apparatus:

[0034] Dust Monitor - Lab scale dust monitor uses white light to determine dust levels of materials dropped into the sampling chamber.

Substrate:

[0035] Coal samples, mixture of size fractions to generate sufficient dust to study.

Procedure:

[0036] 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

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PCT/US2016/029519 samples at 140F 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.

[0037] 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 2

Test	C2%	4HT%	Dust Area + 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

[0038] 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 3

Test	C2%	4HT%	Dust Area + 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

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PCT/US2016/029519 [0039] 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.

[0040] Example 3 - Foam Stability - 4HT was added to a known foaming agent, “C4”, an anionic surfactant, sodium olefin (Cu-Cie) sulfonate to determine its effect on foam stability.

Solutions:

[0041] 200 mL solutions at ambient temperature (72°F)

Apparatus:

[0042] Waring Commercial Blender (Model 7011G) marked with 50 mL graduations

Measurements:

- Maximum foam height (to nearest 25 mL)

- Ά life time (in sec) - time for lOOmL of solution to drain back into liquid phase

Procedure:

[0043] 200mL 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 (lOOmL) returned back to liquid state. The amount of time that passed until the liquid-foam interface hit the 100mL mark was recorded as “foam Ά life time.”

Results are shown in Tables 3 and 4

Table 3

		Foam 1/2 life (mirrsec)
C4%	C4 only	C4 + 4HT 1.5%	C4 +4HT 0.75% + C2 0.75%	C4 + C2 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

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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 4

C4%	4HT%	Foam 1/2 life (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 (Cu-Cie) sulfonate [0044] 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.

[0045] Additional tests were undertaken in waters of varying hardness. These tests looked at soft (40 ppm as CaCCh), medium (80 ppm Ca as CaCCh) and very hard (600 ppm Ca as CaCCh) 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 5

Foam 1/2 Life (min:sec)

C4%	4HT%	40 ppm	80 ppm	600 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

Claims

1. A method of treating coal comprising adding a nitroxyl radical compound (NRC) to said coal, wherein said nitroxyl radical compound is conjointly employed with a dust control agent (DCA) comprising a polymer, 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.

2. The method of claim 1, wherein the NRC has the following structure:

R1 wherein

R2, R3, Rs, R9 are each independently of one another substituted or un-substituted Ci - Cis alkyl, C2 - Cis alkenyl, or C2 - Cis alkynyl; or

R2 and R3 and/or Rs and R9 together form, with the linking carbon, a C3 - C12 cycloalkyl radical; and

R4, R5, R6, R7 are each independently of one another hydrogen, substituted or un-substituted Ci Cis alkyl, C2 - Cis alkenyl, or C2 - Cis alkynyl;

X is —O—, —O—C(O) —, —NR10— or —NR10—C(O) —; wherein

Rio is hydrogen, phenyl, or Ci - Cis alkyl; and wherein

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3. A method as recited in claim 1 wherein said NRC is added to said coal in an amount of 0.001 to

10 lbs. per ton (0.4536 g to 4536 g per 907.2 Kg) of coal.

4. A method as recited in claim 1 wherein said NRC is selected from the group consisting of dialkyl nitroxyl radicals, l-oxyl-2,2,6,6-tetraalkylpiperidine compounds, 1-oxyl-2,2,6,6- tetramethylpiperidine, l-oxyl-2,2,6,6-tetramethylpiperidin-4-ol (4-HT), 1-oxyl-2,2,6,6tetramethylpiperidin-4-one, l-oxyl-2,2,6,6-tetramethylpiperidine-4-yl acetate, 1-oxyl-2,2,6,6tetramethylpiperidin-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-tertbutylbenzoate, bis( 1 -oxyl-2,2,6,6-tetramethylpiperidin-4-yl)succinate, bis( 1 -oxyl-2,2,6,6tetramethylpiperidin-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(l-oxyl-2,2,6,6-tetramethylpiperadin4-yl)phthalate, bis( 1 -oxyl-2,2,6,6-tetramethylpiperidin-4-yl)isophthalate, bis( 1 -oxyl-2,2,6,6tetramethylpiperidinyl-4-yl)terephthalate, bis( 1 -oxyl-2,2,6,6-tetramethylpiperidin-4yl)hexahydroterephthalate, N,N’-bis(l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipamide, N-loxyl-2,2,6,6-tetramethylpiperidin-4-yl-dodecyl succinimide, 1 -oxyl-4-methoxy-2,2,6,6tetramethylpiperidine, 1 -oxyl-4-amino-2,2,6,6-tetramethylpiperidine, 4-butoxy-2,2,6,6tetramethylpiperidine and 1 -oxyl-4-acetamino-2,2,6,6-tetramethylpiperidine.

5. A method as recited in claim 4 wherein said NRC is l-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.

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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 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 quatemaryamine, dimethylamine, and epicholohydrin.

10. 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 by weight of a), there are 1-100 parts by weight of b), and wherein if a) and c) are present, for every 1-5 parts by weight of a) there are 0.01-10 parts by weight of c), and wherein if all three of a) and b) and c) are present, for every 1-5 parts by weight of a) there are 1-100 parts by weight of b) and 0.01-10 parts by weight of c), wherein said dust control agent (DCA) comprises a polymer, 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.

2016266725 25 Mar 2020

11. A composition as recited in claim 10, wherein the NRC has the following structure:

wherein

R4, R5, Re, R7 are each independently of one another hydrogen, substituted or un-substituted Ci Cis alkyl, C2 - Cis alkenyl, or C2 - Cis alkynyl;

X is —O—, —O—C(O) —, —NR10— or —NR10—C(O) —; wherein

Rio is hydrogen, phenyl, or Ci - Cis alkyl; and wherein

12. A composition as recited in claim 10 wherein said a) NRC is selected from the group consisting of dialkyl nitroxyl radicals, l-oxyl-2,2,6,6-tetraalkylpiperidine compounds, 1-oxyl-2,2,6,6tetramethylpiperidine, l-oxyl-2,2,6,6-tetramethylpiperidin-4-ol (4-HT), 1-oxyl-2,2,6,6tetramethylpiperidin-4-one, l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl acetate, 1-oxyl-2,2,6,6tetramethylpiperidin-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-

2016266725 25 Mar 2020 butylbenzoate, bis( 1 -oxyl-2,2,6,6-tetramethylpiperidin-4-yl)succinate, bis( 1 -oxyl-2,2,6,6tetramethylpiperidin-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(l-oxyl-2,2,6,6-tetramethylpiperadin4-yl)phthalate, bis( 1 -oxyl-2,2,6,6-tetramethylpiperidin-4-yl)isophthalate, bis( 1 -oxyl-2,2,6,6tetramethylpiperidin-4-yl)terephthalate, bis( 1 -oxyl-2,2,6,6-tetramethylpiperidin-4yl)hexahydroterephthalate, N,N’-bis(l-oxyl-2,2,6,6-tetramethylpiperidin-4-yl)adipamide, N-loxyl-2,2,6,6-tetramethylpiperidin-4-yl-dodecyl succinimide, 1 -oxyl-4-methoxy-2,2,6,6tetramethylpiperidine, 1 -oxyl-4-amino-2,2,6,6-tetramethylpiperidine, 4-butoxy-2,2,6,6tetramethylpiperidine and 1 -oxyl-4-acetamino-2,2,6,6-tetramethylpiperidine.