An Algorithm for Evaluation of Mining Cycle Parameters and Analysis of Periodic Roof Weighting Using Monitored Longwall
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An Algorithm for Evaluation of Mining Cycle Parameters and Analysis of Periodic Roof Weighting Using Monitored Longwall Shield Pressures and Shearer Location V. N. S. Prasad.M 1 & Debasis Deb 2 & Anand Kumar 2 & A. K. Mishra 1 Received: 30 June 2020 / Accepted: 12 November 2020 # Society for Mining, Metallurgy & Exploration Inc. 2020
Abstract Shield leg pressure data from all shields and shearer location with time stamp from a mechanized longwall face are monitored and recorded in a surface computer. These data contain random noise due to power failure, leakage of legs, bad sensor reading and other maintenance or geo-mechanical problems. An algorithm is developed to detect mining cycle parameters such as setting and final pressures and duration of the cycle from these data for the analysis of periodic roof weighting phenomena. The intensities and persistence of periodic roof weighting are the vital information to the mine management to take judicious decision on longwall operation. The paper presents details of the algorithm which identifies 96% of mining cycles from the noisy data belonging to consecutive 5 months or 410 m of face advancement. Based on this analysis, 2 types of periodic roof weighting phenomena are detected, namely, (i) normal type—having peak intensity of 75 to 90% of yield pressure, interval of occurrences of about 10 to 15 m with persistence of 3 to 4 m and (ii) severe type—peak intensity over 90% of yield pressure, interval of 25 to 40 m with persistence of over 10 m. It is envisaged that these phenomena have direct relationship with main roof thickness, its overhung length and material properties. Keywords Shield pressures . Periodic roof weighting . Mining cycle algorithm . Peak intensity . Yield pressure
1 Introduction Interest in the interaction between longwall face supports and surrounding rock strata has grown steadily since 1980s with the increasing use of shield-type hydraulic face supports, which provide excellent ground control in longwall mining. In the study mine, Adriyala Longwall Project (ALP), two-leg shields are installed having total support capacity of 2 × 1152 tonnes. This is the first longwall panel in India in which the panel width and length are of 250 m and over 2 km, respectively. Digital pressure sensors are mounted in each hydraulic leg of 146 shields, and pressure data at every 10 s are collected and sent to a surface computer. Each day, over 20 MB of raw data is being recorded and stored in the surface computer. In this study, 5 months of big data are further analysed to identify the key features of the interaction between * Debasis Deb [email protected] 1
IIT(ISM), Dhanbad, India
2
IIT, Kharagpur, India
shield supports and roof, floor and coal seam as well as to extract information like parameters of mining cycles and periodic roof weighting. Apart from that, position of the shearer is also sent concurrently providing essential information regarding the rate of advancement of the longwall face. One of the earlier studies on longwall shield pressure monitoring
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