Handbook for Methane Control in Mining - AMMSA

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The coal had been surface mined. Surface-mined coal normally has a very low methane emission;however, the coal had been heated in a dryer 12 to remove moisture just before being loadedinto the silo. The 24-hr conveyor belt grab sample emission was measured at 14 ft 3 /ton. Beforethe explosion, the top was ventilated with a 7,500-cfm wet dust scrubber system that operatedonly during loading. An unworkable 13 natural ventilation methane stack was located on the siloroof. There was also a methane detector at the roof of the silo (probably in a location where themethane did not accumulate).After the explosion, the silo was put back into operation with these new methane control anddamage prevention measures:• Continuous ventilation was provided at the top. A 14,000-cfm dust scrubber system 14operated when the silo was loading. When loading stopped, another fan, a 20,000-cfmforcing fan, automatically turned on, and this fresh air was deflected downward towardthe coal surface.• Other openings at the top were provided to supply fresh air in the event of fan failure.• A new methane monitoring system that used several sensing heads was installed. Usingseveral heads reduced the chance that a methane accumulation would be missed.• A large portion of the roof was provided with a lightweight sheet metal cover that couldprovide some explosion relief without damage to the main structure of the silo. 15These measures provided for continuous ventilation in a quantity matched to the gas level andprovided for monitoring in locations where methane was likely to accumulate. They considerablyreduced the chance of a silo explosion.145REFERENCESAMCL [1985]. Survey of methane accumulation within coal silos. Calgary, Alberta, Canada:Associated Mining Consultants Ltd.CFR. Code of federal regulations. Washington DC: U.S. Government Printing Office, Office ofthe Federal Register.12 Hot coals from the dryer were a probable source of the ignition. Hot coal detection systems can flag this problemand should be installed if the coal is gassy.13 The idea behind a natural ventilation methane stack is to use the density difference between methane and air toproduce a chimney effect that ventilates the silo. However, neither the stack height nor the methane concentration atany silo would ever be high enough to make a natural ventilation methane stack function.14 Dust problems precluded the conversion to an open-top silo.15 The National Fire Protection Association has a guide for venting of deflagrations [NFPA 1998], i.e., methane anddust explosions.
146Kolada RJ [1985]. Investigation into methane accumulation in coal storage silos. SME preprint85–346. Littleton, CO: Society for Mining, Metallurgy, and Exploration, Inc.Kolada RJ, Chakravorty RN [1987]. Controlling the hazard of methane explosions in coal storagefacilities. In: Mutmansky JM, ed. Proceedings of the Third Mine Ventilation Symposium(University Park, PA, October 12–14, 1987), pp. 334–339.LaScola JC, Matta JE, Kissell FN [1981]. Assessing the methane hazard of gassy coals in storagesilos. Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 8525. NTIS No.PB81226920.Matta JE, LaScola JC, Kissell FN [1978]. Methane emissions from gassy coals in storage silos.Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 8269. NTIS No.PB277912.Mikhail MW, Patching TH [1980]. Size degradation of bituminous coal from western Canada.CIM Bull May:105–110.NFPA [1998]. NFPA 68: Guide for venting of deflagrations. Quincy, MA: National Fire ProtectionAssociation.Stokes DA [1986]. Fording Coal Ltd. silo explosion. CIM Bull 75(891):56–60.
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TMIC 9486Information Circular/2006H
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ORDERING INFORMATIONCopies of Natio
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ILLUSTRATIONS—ContinuedPage4-6. U
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HANDBOOK FOR METHANE CONTROL IN MIN
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4Below 5%, called the lower explosi
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6reduced pressure, except at very l
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8Static electricity. Protection aga
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10Figure 1-4.—Estimated methane c
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12LAYERING OF METHANE AT THE MINE R
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14good eyesight. 24methane level.Ot
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16a material balance indicated that
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18As an example, assume that themet
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20Figure 1-10.—Relative frequency
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22Davies AW, Isaac AK, Cook PM [200
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24Margerson SNA, Robinson H, Wilkin
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CHAPTER 2.—SAMPLING FOR METHANE I
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29USING PORTABLE METHANE DETECTORST
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Out-of-range gas concentrations in
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Figure 2-3.—Recorder chart from a
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35Industrial Scientific Corp. [2004
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38peaks, not the overallmethane lev
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40hung on J-hook assemblies, which
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42Methane dilution effectiveness.Th
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44found that effective scrubber ope
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46When the scrubber exhaust is not
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48Methane monitors are usually moun
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50to use radial bits instead of con
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52Mott ML, Chuhta EJ [1991]. Face v
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54Service, Centers for Disease Cont
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56Methane accumulationsaround thesh
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58corner and by 43% at supportNo. 4
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60When using water sprays to reduce
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62Cecala AB, Zimmer JA, Thimons ED
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64DESIGNING BLEEDER SYSTEMSAs part
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66Caved area characteristics. The c
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68then move this gas into the activ
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70perform tests to determine whethe
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72A major purpose of the bleeder sy
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74• Inlets to the pillared area n
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76REFERENCESCFR. Code of federal re
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78Methane is released into each min
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80Figure 6-1.—Gas content of coal
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82Figure 6-3.—Simplified illustra
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842. In-mine inclined or vertical b
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861. Packed cavity method and its v
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88Table 6-3.—Methane capture rati
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90Early experiences with this metho
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9211. At the surface installation (
Page 99 and 100: 94• Estimated cost for moderately
Page 101 and 102: 96Thakur PC [1981]. Methane control
Page 103 and 104: 98Anomalous, unanticipated methane
Page 105 and 106: 100Vertical methane drainage boreho
Page 107 and 108: 102Figure 7-2 shows a mine entry ap
Page 109 and 110: 104obvious solution to this problem
Page 111 and 112: 106Figure 7-8.—Hypothetical gas c
Page 113 and 114: 108Lama and Bodziony [1998] compile
Page 115 and 116: 110In-mine methane drainage systems
Page 117 and 118: 112Iannacchione AT, Ulery JP, Hyman
Page 119 and 120: 114More sophisticated reservoir eng
Page 121 and 122: 116coal lithotype on gas content is
Page 123 and 124: 118FORECASTING REMAINING GAS-IN-PLA
Page 125 and 126: 120⎛ y⎞⎜⎛⎞ ⎛ ⎞= ⎜
Page 127 and 128: 122emissions. The geometry and size
Page 129 and 130: 124Reservoir models require a subst
Page 131 and 132: 126King GR, Ertekin T [1989a]. A su
Page 133 and 134: 128an area of 314 ft 2 would requir
Page 135 and 136: 130In the case of the abovementione
Page 137 and 138: 132FILLING SHAFTS AT CLOSED MINESFi
Page 139 and 140: 134Hinderfeld G [1995]. Ventilation
Page 141 and 142: 136To calculate the effectiveinert,
Page 143 and 144: 138exhaust. The remaining diesel ex
Page 145 and 146: 140required only 4 min. As a result
Page 147 and 148: 142Figure 11-1.—Desorption test a
Page 149: 144enclosed in a tunnel-like struct
Page 153 and 154: 148air in a 6-ft by 9-ft by 6.5-ft
Page 155 and 156: 150represents flammable mixtures. F
Page 157 and 158: 152• In Eastern Europe, petroleum
Page 159 and 160: 154Category II applies to domal sal
Page 161 and 162: 1562. Monitoring for gas and taking
Page 163 and 164: 158These mines typically have large
Page 165 and 166: 160Dave Graham is the safety and he
Page 167 and 168: 162Figure 13-2.—Examples of metha
Page 169 and 170: 164REFERENCESAndrews JN [1987]. Nob
Page 171 and 172: 166APPENDIX A.—ONTARIO OCCUPATION
Page 174 and 175: 169CHAPTER 14.—PREVENTING METHANE
Page 176 and 177: Ways to confirm the presence of gas
Page 178 and 179: 173The tunnel face is usually venti
Page 180 and 181: 175Figure 14-5.—TBM ventilation s
Page 182 and 183: face. While one of these elements a
Page 184 and 185: 179ELIMINATING IGNITION SOURCESElec
Page 186 and 187: 181INDEXAAbnormally gassy faces....
Page 188 and 189: 183NNatural ventilation, coal silos
Page 190 and 191: Delivering on the Nation’s Promis
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