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|In recent years, improvements made to the longwall system have accelerated at a faster pace than those made to the gate entry development system. As a consequence, unless planned years ahead of time, extending the panel length is nearly impossible without some innovative approach. At Cyprus Amax Coal's Emerald mine the G panel length was extended by 3,500 ft- by developing three entries across it to facilitate development of its headgate and tailgate entries simultaneously when the adjoining F panel was in operation. After evaluating alternative supporting methods and associated risks, determination was made to backfill these entries and crosscuts using a low strength flyash cement mixture prior to mining thru. Instrumentation was also used to monitor the stress change or front abutment stress in both the coal and the backfilled material ahead of the face. Longwall mining thru these three entries took about four eight-hour shifts and proved to be very successful. The designed flyash cement mixture provided adequate roof stability and caused no difficulty in the shearer's cutting while eliminating an in-panel longwall face move and minimizing the risk of roof or floor failure in the in-panel openings, or in the worst scenario loss of the face during the longwall cutting thru. This approach provided the intended result of extending G panel and recovered about one million tons of coal. This paper summarizes the engineering design of the cutting-thru project and flyash cement mixture, front abutment stress changes within the longwall coal block, backfilled material, and coal pillars ahead of the longwall face, and our underground observations|
Additional chapters/articles from the SME-ICGCM book 16th International Conference on Ground Control in Mining (ICGCM)
|Longwall Mining-Through the Backfilled In-Panel Entries at C||Performance of Various Standing and Cribless Tailgate Suppor||Measurement of Effects of Interaction and Influence on Mine||Effects of Longwall Mining on Streamflow in the Pittsburgh S||Longwall Surface Subsidence Prediction Through Numerical Mod||Long-term Subsidence Over Longwall Chain Pillar Systems and||Subsidence Prediction Influence Assessment and Damage Contro||Formation of Face Headings Using Stress Relief at Asfordby M||Significant Weighting Events on the Longwalls in the Phalen||Full-face Pressure Monitoring in Medium-Weak Roof Condition||Research on the Interaction Between Roof Strata and Shield S||Roof Instability of Longwall Face at Ikeshima Colliery||Gob Canopy Roof Support for Difficult Natural Conditions||Yielding Cement Roof Supports for Longwall Mining||Management of the Dynamic Phenomena of Rock Pressure in Unde||Continuing Development of Innovative Cable Support Systems||Extending the Limits of Strata Bolting by the Use of Flexibl||Implementation and Evaluation of Roof Bolting in MICARE Mine||New Methods and Technologies of Roofbolting in Australia Coa||New Design Criteria for Roof Bolt Systems||Control Mechanism of a Tensioned Bolt System in the Laminate||A Study of the Performance of Glass Fibre Rock Reinforcement||A Method for the Selection of Rock Support Based on Bolt Loa||Strategies for the Application of Rockbolting Technology to||A Troubleshooting Guide for Roof Support Systems||A Statistical Overview of Retreat Mining of Coal Pillars in||Full-Scale Performance Evaluation of Mobile Roof Supports||Effect of the Interchamber Pi Yield on the Surface Strains i||Salt Pillar Design Equation||Case Study of Conditions Observed During the Removal of a Hi||Case Study of the Effect of Stratigraphic Location on Roof S||Ground Control and the Inundation of the Retsof Mine||Weatherability Test of Rocks for Underground Mines||Shear Strength Characteristics of Soft Rock Joints Based on||Comparison of Pillar Strengths Calculated Using Empirical Eq||Effects of In-seam and Near-seam Conditions and Asymmetric P||Ground Control Worker Safety During Extended Cut Mining||Analysis of Extensometer Data from a Room Widening Experimen||Airbag Support for Ground Control in Thin Seam Coal Mining||Development of a Statistical-Analytical Approach for Assessi||Ground Control Criteria for Coal Reserve Optimization in Mul||Calcium Aluminate Kiders in Hard Rock and Coal Mining||Simplified Pre-and Post-Processing Technique for Performing|