SUPERIMPOSED HIGHLY GAS-BEARING COAL BED SERIES DEVELOPMENT METHOD Russian patent published in 2006 - IPC E21C41/18 E21F7/00 

FIELD: mining, particularly methods of underground mining for brown or hard coal.

SUBSTANCE: method involves cutting one coal bed of coal bed series by extraction pillars preparation, wherein the extraction pillars are prepared by forming and supporting conveyorways and airways so that coal block remains between the conveyorways of cut extraction pillar and airway of extraction pillar to be cut along with vent cross cuts forming between them; cutting each extraction pillar along with guard support installing in maintained conveyorway section located beyond breakage face at mine goaf border and with erecting bridges in vent cross-cuts from mine goaf side; demethanizing mine goaf. Mine goad demethanization is carried out by vent means, which create methane-and-air mixture of air flow extracted from breakage face through mine goaf into above conveyorway section due to pressure drop maintenance in mine. The air flow is mixed with fresh air in the conveyorway section and is divided into two parts near vent cross cut proximal to breakage face. The first part of air flow moves via the vent cross cut and then via airway from working area and fresh air is added to the first air flow part. Mine goaf demethanization is also executed by means of degassing means by capturing another methane-and-air flow part flowing via mine goaf near non-maintained conveyorway section via degassing holes drilled in massif to be cut from airway and directed towards mine goaf. Lengths of active gas-releasing zones in undermined and overmined beds are preliminarily determined. Gas collector is erected in above active gas-releasing zones beyond breakage face in conveyorway as extraction pillars are cut. The gas collector is erected by serially forming two transversal bridges having ends extending beyond conveyorway contour. Each transversal conveyorway partition is erected from mine goaf side in front of current vent cross cut when breakage face has left behind next vent cross-cut along with simultaneous blocking vent cross-cut located between previously formed one and adjacent vent cross cut proximate to breakage face with bridges. Gas collector bridge proximate to breakage face is spaced a distance of not greater than length of active gas-releasing zone in overmined beds from the breakage face. Another partition, which is remote from breakage face, is spaced a distance of not greater than length of maximal active gas-releasing zone in overmined beds from the breakage face. As breakage face advances the goaf mine is demethanized in two stages. At the first stage methane-and-air flow part to be moved via mine goaf near non-maintained conveyorway section is displaced towards upper unloaded zone layers of undermined beds in zone of transversal gas collector partition influence, which results in rapid methane-and-air mixture concentration and output increase. Then above flow part is captured via degassing holes. The degassing holes are oriented so that each degassing hole cluster is located in zone of transversal gas collector partition influence. Then as breakage face moves during extraction pillar cutting next gas collector is erected. After the first coal bed cutting next coal beds of coal bed series are excavated.

EFFECT: increased safety due to optimal gas factor.

10 dwg