Handbook for Methane Control in Mining - AMMSA

127CHAPTER 9.—CONTROL OF METHANE DURING COAL MINESHAFT EXCAVATION AND FILLINGBy Fred N. Kissell, Ph.D. 1In This Chapter Ventilation and methane sampling guidelines for conventional shafts Dealing with restricted spaces where methane can accumulate Ventilation and methane sampling at raise bore drillsand Filling shafts at closed coal minesIt is not unusual to encounter methane gas during shaft excavation or shaft-filling operations.Shafts into coalbeds usually produce the most methane, so the information in this chapter appliesprimarily to shafts at coal mines. Nevertheless, much of the information is relevant for noncoalmines that have methane in the mine or in the overlying strata.METHANE IN SHAFTS EXCAVATED BY CONVENTIONAL MEANS(DRILL, BLAST, MUCK)Ventilation. Shafts excavated by conventionalmeans are ventilated with a fan on the surfaceconnected to ductwork that extends down intothe shaft (Figure 9–1). Shafts into coalbedsshould have ventilation systems designed tohandle the higher gas flows to be expected asthe shaft excavation passes through any overlyinggas-containing strata and nears the coalbedto be mined. Following are some simpleventilation guidelines for the minimum amountof air required and the selection of the ventilationduct:Figure 9–1.—Mine shaft under construction.• Provide enough air to meet the minimumOSHA tunnel requirement of30 ft/min air velocity in the open shaft,as specified in 29 CFR 2 1926.800(k)(3).For example, a 20-ft-diam shaft having1 Research physical scientist, Pittsburgh Research Laboratory, National Institute for Occupational Safety and Health,Pittsburgh, PA (retired).2 Code of Federal Regulations. See CFR in references.