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|Jim Walter Resources, Inc. (JWR), has successfully longwall mined for many years at depths ranging from 1200'-2500'. However, full pillar extraction has proven difficult and generally economically unfeasible. Overburden and redistributed stresses at these depths require relatively large pillars, which become unmanageable with most pillar extraction practices. The economic benefits of taking gateroad pillars as part of a longwall face have been recognized for some time, including increased life of mine recovery, elimination of belt moves, reduced overcast requirements, and improved longwall to continuous miner ratios. Until recently, the associated risks of pulling pillars prevented any extensive use of this concept at JWR. Due to geological, economic, and longwall repeatability problems, JWR accepted the risks, and undertook pillar extractions with longwall faces in several different applications. The applications included taking a stable pillar (250' wide) as a longwall panel, taking yield pillars on the headgate and tailgate of panels, taking yield pillars and stable pillars in the middle of a panel, mining through chain pillars in the middle of a panel, and taking a support pillar on the tailgate end of a panel. This paper describes the background and experience of pillar extraction with longwalls at JWR.|
Additional chapters/articles from the SME-ICGCM book 17th International Conference on Ground Control in Mining (ICGCM)
|Gateroad Pillar Extraction Experience at Jim Walter Resource||Stability of Backfilled Cross-panel Entries During Longwall||Mining Through In-panel Entries and Full-face Recovery Room||Cutable and Variable Yield Cement Cribbing Successfully Supp||International Experience with Longwall Mining into Pre-drive||Analysis of Geologic and Geotechnical Conditions and Their E||Comparison of Ground Conditions and Ground Control Practices||Application of Microseismic Monitoring to Longwall Geomechan||Control of Hard-to-Collapse Massive Roofs in Longwall Faces||A Study of Periodic Weighting of Longwall Supports||Effects of Panel Mining Sequence and Retreat Direction on th||Controlling Roof Beam Failures From High Horizontal Stresses||Roof Control Under Conditions of Shallow Depth and High Hori||Assessment of Roadway and Yielding-pillar Performance During||Practical Stress Modeling for Mine Planning||The Design of Room and Pillar Mining Systems in the UK||Geotechnical Planning and Development of the BHP Minerals Sa||Coal Pillar Life Prediction in the Vaal Basin, South Africa||An Analytical Approach to Determine Stress Distribution in L||In Situ Strength Testing of Rocks with the Borehole Penetrom||Performance and Safety Considerations of Hydraulic Support S||A Decade of Mobile Roof Support Application in the United St||A Critical Study of Strata Behaviour During Extraction of Pi||Progression of Longwall Gateroad Support as Conditions Chang||Application of the Coal Mine Roof Rating, Derived from Drill||The Effects of Reduced Annulus in Roof Bolting Performance||Laboratory and In Situ Results of a Slip Nut Yielding Rock B||Field Monitoring of Rock Bolting Performance in Weak Roof St||A Case Study of Bolt Performance in a Two-entry Gateroad||Automated Temporary Roof Support Systems: An Update||Safety and Productivity Innovations in Mechanized Bolting||Factors Influencing Intersection Stability in U.S. Coal Mine||Analysis of the Effect of Rate of Extraction on Strain Devel||Analysis of Panel Stability for Post-Mining Slurry Injection||Development of Timedependent Surface Subsidence Over the Tot||Transversely Elasto-Plastic Analysis of Surface Subsidence A||Landslide Occurrence and Causation in Steep Slope Areas of A||Rock Bursting and Seismicity During Ramp Development, Lucky||Advances in Remote Sensing Techniques for Monitoring Rock Fa|