The vast majority of Polish mines are exposed to operating in a methane hazard situation. In a small number of cases, it is possible to minimise such risks using ventilation methods only. The most effective way to combat the methane hazard is to introduce active comprehensive demethanation of the rock mass.
Comprehensive demethanation covers all stages of conducting demethanation, including research, laboratory, design and implementation work, with constant supervision of the engineering staff and with the participation of qualified employees: mine supervisors, methane drillers-measurers and helpers.
The accomplishment of comprehensive demethanation with respect to underground work includes:
- drilling of drainage holes, i.e., drilling holes in an intact coal seam (in the rock mass, as preliminary or anticipatory demethanation), drilling holes to the goaf space in active mine workings, or drilling holes to the goafs of a partitioned space; once a drainage hole has been drilled to the target depth, it is incorporated into the underground demethanation network,
- maintenance of the underground demethanation network, which consists of ongoing inspections, measurements and adjustments in order to ensure effective and stable methane capture with the best possible parameters; the scope also includes continuous maintenance of the pipeline network as well as possible repairs, refitting and ongoing drainage,
- construction of a network of demethanation pipelines, intended to prepare the planned sections of gas pipelines, constituting a negative pressure installation connected to a demethanation station,
- conducting constant monitoring of the parameters of the captured gas, both at the bottom of the mine and through monitoring in the demethanation station.