ICGCM Papers:
Longwall Mining
 
 
Longwall Recovery at Bailey Mine - Ground Control Challenges and Solutions
28th International Conference on Ground Control in Mining
Longwall Recovery at Bailey Mine - Ground Control Challenges and Solutions
by
Daniel Su, Consol Energy Inc., Canonsburg, PAGreg Hasenfus, Consol Energy Inc., Canonsburg, PAT.J. Morris, Consol Energy Inc., Canonsburg, PAL. Stull, Consol Energy Inc., Canonsburg, PAM. Petrovich, Consol Energy Inc., Canonsburg, PA
Download PDF Add to My Library
[Conference] 28th International Conference on Ground Control in Mining
[Price] Free  [Comments] 0
[Topical Area] Longwall Mining
[Author] Daniel Su, Consol Energy Inc., Canonsburg, PAGreg Hasenfus, Consol Energy Inc., Canonsburg, PAT.J. Morris, Consol Energy Inc., Canonsburg, PAL. Stull, Consol Energy Inc., Canonsburg, PAM. Petrovich, Consol Energy Inc., Canonsburg, PA
[Abstract] 
This paper describes the issues encountered at the longwall recovery area by one of Bailey Mine’s two longwall faces in the past 3 years and the proactive actions taken by CONSOL management and engineering to mitigate them. The issues derived primarily from the following causes: (1) irregular roof coal and draw slate thickness, (2) presence of thick sandstone at the recovery area and extremely weak rocks below the sandstone, (3) close proximity of a regional anticline, (4) low shield set pressure and tip load, and (5) ineffective primary roof support that led to progressive failure of the headgate roof as the longwall face approached. The combination of anticline in close proximity contributed to extensive fracturing of the sandstone. More than 24 inches of face pot out frequently occurred from Shields #50 to #150 due to the presence of thick draw slate and irregular roof coal near the recovery area, which resulted in a face height of 108 inches and which was 18 inches higher than the maximum reach of the face shields. During longwall meshing, where face advance rate slowed down considerably, fractured sandstone would often break loose and push down the canopy of the face shields which made shearer pass impossible.
To improve headgate condition and face condition at the longwall recovery area, several proactive actions were taken incrementally over the past three years which included: (1) conducting in-mine roof coring at and near the recovery areas, (2) mapping of draw slate and roof coal thickness in the headgate and tailgate of the recovery area, in the recovery chutes, and in the Mains, (3) increasing pump pressure to 4400 psi and shield set pressure to 285 bars, (4) installing additional cable bolts and roof screen to prevent progressive failure of the headgate immediate roof, (5) fully-grouting the 16-ft supplemental cable bolts to improve headgate support stiffness, and (6) gluing the headgate roof at and near the recovery areas with polyurethane which could also fully grout the cable as well as the 8-ft primary bolts.
As a result of the collective efforts of CONSOL management and engineering, the proactive actions have helped reduced longwall recovery delays at Bailey Mine from 21 days in 2006 to nearly zero delay in 2009.