Analysis of panel design experiments in advanced longwall mines

Panel design and its geometry affects the productivity, strata control and operational costs of longwall mining. Selection the suitable panel size is a critical stage which needs a wide range of geological, technological and economical inputs. Seam height and overburden are two uncontrollable factors which play an important role in longwall mine design. Panel width, panel length and layout of whole mine are main design parameters which are selected based on uncontrollable factors and technological restrictions. In this paper the geometrical characteristics of 61 longwall panels in 46 operating mines of USA have been applied for statistical analysis and extracting some experimental design benchmarks. The analysis shows that average seam height, panel overburden, panel width and panel length are 2.26, 200, 361.5 and 3455 respectively. Average panel width to depth ratio is 1.53 and panel length to width ratio is 9.55. The 3D data analysis reveals that overburden is more important than seam height in enlargement of longwall panels and maximum of the panel area (panel length multiplied by panel width) occurs when the overburden is between 150 to 250 meters and seam height is from 1.5 to 2.5 meters. Also, 50 percent of the studied advanced longwall panels the width to depth ratio varies from one to two. It confirms that even in shallow panels the designers have selected larger panel dimensions to enhance the productivity by considering some subsidence problems and high caving pressures.