A Prognostic View on the Continuous Mining Machine based System-Reliability to Augment Availability of Allied Sub-Systems

Abstract

Continuous miner (CM) is an underground coal mining machine, capable of producing coal from underground at a considerably higher rate. With incessant modernization, demand for power is increasing rapidly, which deserves a boost in coal production in India. Opencast mining in India contributes to maximum share of overall coal production as compared to underground coal mining. Opencast mining is feasible for the seams near the surface. However, with higher rate of extraction the near surface seams are getting quickly depleted, this necessitates the implementation of an effective cutting edge underground mining technology to sustain the level of coal production to support the indigenous demand of coal.

Government of India has recently taken the initiative to implement cutting edge underground mining technology; such as CM and other mass production technology to boost underground mine productivity. These machines are getting implemented recently, having a broad scope of research and development in Indian as well as global mining scenario.

This paper focuses on the mechanical factors contributing to equipment downtime along with statistical reliability analysis of two continuous miner machines working in two different panels of an underground mine in a leading coal producing company of the country. Reliability analysis includes statistical methods such as, trend test, serial correlation test including distribution fitting. Through trend test and serial correlation test, Time Between Failure (TBF) data is first checked whether it is free from any trend and serial correlation or not, data free from trend and serial correlation are suitable for distribution fitting. This TBF data is fed to proper probability distribution, from where the reliability curves are obtained.

In this machine mining based study, the overall CM package is divided into few sub-systems such as; electrical, cutter and gathering arm, traction, hydraulic, chassis, feeder breaker, shuttle car, conveyor, CM conveyor etc. The availability and reliability of all these sub-systems are calculated to identify the vulnerable sub-systems contributing to maximum percentage of undesired equipment stoppage, hence lowering productivity. Some important mechanical factors are identified from physical verification in those two panels about the machines and systems of the mine. Out of which the potential factors are; conveyor breakdown, power cut and cable fault, traction chain wear out and pad change etc. The possible reasons of this lower reliability trend for that specific sub-system is discussed with experienced mining personnel working in the mine and based on that few recommendations as well as new maintenance strategy are suggested to avoid recurrence of these failures and to ensure better availability of the system.