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.

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), O, NR.sub.10 or NR.sub.10C(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, OC(O), O, NR.sub.10 or NR.sub.10C(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

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, OC(O), O, NR.sub.10 or NR.sub.10C(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, OC(O), O, NR.sub.10 or NR.sub.10C(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 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 2Dust Control Improvement

Apparatus:

[0036] Dust MonitorLab 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 3Foam 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 F.)

Apparatus:

[0044] Waring Commercial Blender (Model 7011G) marked with 50 mL graduations

Measurements:

[0045] Maximum foam height (to nearest 25 mL) [0046] 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 life time.

Results are shown in Tables 3 and 4

TABLE-US-00004 TABLE 3 Foam 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 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 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