Special issue on reliability and maintenance of mining systems

Modern day mining operations are less physical and more cognitive, because of the replacement of manual labour with mechanised and automatic systems to meet the ever growing demands for coal, ore and other minerals. Although such mining systems are expected to perform continuously or round the clock, there are design and other unforeseen problems that limit their ability to meet mine operators' requirements for system performance and effectiveness. Often this is because of poorly designed reliability and maintainability characteristics combined with poor maintenance strategy, which lead to unscheduled stoppages or failures resulting in huge economic losses. Thus, reliability and maintenance of mining systems is a very important issue in modern day mining operations.

The purpose of this special issue of IJMRE is to provide a timely review of research efforts on the topic of Reliability and Maintenance of Mining Systems, covering both theoretical and applied research areas. This is intended to contribute towards understanding the strategic role of reliability and maintenance in management of mechanised mining systems. This special issue of IJMRE consists of six papers to address the following topics:

	Reliability, maintainability and availability of mining systems
	Maintenance strategy
	Condition monitoring and condition based maintenance
	Maintenance and safety

The first paper, ‘Optimal replacement intervals for shovel dipper teeth’, by Peter Knight, presents an approach for deciding the wear rates and optimal replacement intervals for shovel dipper teeth using grouped failure data with multiple suspensions. The author uses a case study from a mine to demonstrate the applicability and benefits of the approach.

The second paper ‘Mining equipment safety’, which is a review and analysis of methods and improvement strategies by Dhillon, describes the problem of mining equipment safety and presents various facts and figures to address the various important aspects of mining equipment safety. This study reveals that mining equipment safety is a very serious issue and must be considered with utmost care during the mining equipment design and field application phases. The article also discusses human factors related tips for safer mining equipment operations.

In the third article ‘Bayesian statistics and production reliability assessment for mining operations’, the authors Sharma, Haukaas, Hall and Priyadarshini demonstrate a novel application of structural reliability concepts in which a limit-state-based reliability formulation is used for assessing the production and cost probabilities of an ore-hauling mining operation. They use a numerical example to demonstrate the methodology and the interpretation of the probability results. In particular, the article contributes to the state-of-the-art of mining operation productivity assessments.

The fourth article by Srividya, Verma and Sreejith presents a study of ‘Automated diagnosis of rolling element bearing defects using time domain features and neural network’. The article discusses procedures for automated defect detection and diagnosis of bearing from vibrations. It demonstrates the potential of negative log-likelihood values and neural networks for on-line defect detection and diagnosis of bearings. The presented procedures do not require pre-processing of the signal before feature extraction.

The fifth article ‘A control chart guided maintenance policy selection’ by Gupta, Maiti, Kumar and Kumar present a control chart guided methodology for the selection of maintenance policy for mining equipment. The applicability of the method for maintenance policy selection is demonstrated through a case study on an armoured flexible conveyor used in underground coal mines.

In the sixth article ‘Maintenance and reliability of load-haul-dump(LHD) vehicles in an underground hard rock mine’, Vayenas and Wu consider a study of the mechanical breakdowns and accompanying repair times of LHD vehicles deployed in a hard rock mine in the Sudbury area in Ontario, Canada. This study indicates that preventive maintenance consumes significant time but does not appear to cause a major improvement on the mechanical availability of LHDs. Therefore, the authors suggest carrying out a detailed analysis of the various repair activities during the planned maintenance work to investigate the possibility of a more efficient use of the planned maintenance time.

Overall, the set of articles included in this issue covers different aspects of reliability and maintenance of mining systems, as well as approaches to deal with them. I sincerely hope that this Special Issue consisting of six articles will contribute to better understanding of reliability and maintenance of mining systems, and will stimulate new areas of thinking in the management of mechanised mining operations.

Lastly, I would like to express our sincere thanks to the reviewers of this Special Issue of the Journal. Without their inputs, it would have been difficult to ensure the quality of the articles presented. We would also like to thank the Chief Editor of IJMRE Professor Raj Singhal for his valuable support and encouragement in bringing out this Special Issue.