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Purpose The purpose of this paper is twofold: an approach is proposed to determine the optimum replacement time for shovel teeth; and a risk-quantification approached is developed to derive a confidence interval for replacement time. Design/methodology/approach The risk-quantification approach is based on a combination of Monte Carlo simulation and Markov chain. Monte Carlo simulation whereby the wear of shovel teeth is probabilistically monitored over time is used. Findings Results show that a proper replacement strategy has potential to increase operation efficiency and the uncertainties associated with this strategy can be managed. Research limitations/implications The failure time distribution of a tooth is assumed to remain “identically distributed and independent.” Planned tooth replacements are always done when the shovel is not in operation (e.g. between a shift change). Practical implications The proposed approach can be effectively used to determine a replacement strategy, along with the level of confidence level, for preventive maintenance planning. Originality/value The originality of the paper rests on developing a novel approach to monitor wear on mining shovels probabilistically. Uncertainty associated with production targets is quantified.

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Corona Virus Disease (COVID-19) pandemic dramatically impacted the energy sector. About 4.5% of global primary energy consumption dropped in 2020, where coal demand decreased by 220 million tons of coal equivalent. The drop was driven by lower electricity demand due to policies against Covid-19 (i.e., travel restriction, lockdown, and new standard). In particular, the COVID-19 crisis has already created profound uncertainties for the Indonesian coal mining industry as one of the world's largest coal producers and exporters. Coal is the primary energy source for Indonesian electricity, contributing to the national revenues. A debate about action to take, whether to focus on dealing with Covid-19 health or maintaining economic growth, is unavoidable. With the number of cases continuing to rise, we set out to investigate the impact of COVID-19 on Indonesia's coal mining industry. Rapid desk assessment and descriptive statistical approach were used in this study by evaluating secondary data during the pandemic, comparing with previous years before the COVID-19 pandemic. The results revealed a tangible transformation in coal demand, production, and price. Despite domestic coal consumption for power generation decreased, the coal price increased in mid of 2021 due to rising coal demand in China.

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Improving the quality of laboratory services must always be improved in improving the quality of the tri dharma of higher education. Good laboratory management is one of the supporting factors, for that reason, the Department of Mining Engineering manages the laboratory. Laboratory management, in this case, is the laboratory equipment inventory system and laboratory control system. This system will be used to carry out monitoring data on the use of website-based laboratory equipment where the use of laboratory equipment must be carried out systematically. The first step is to create a web system for administration and inventory in the laboratory. In this study, in conducting website-based lab management, it is also necessary to map the problems faced by students in relation to services and supporting infrastructure in the laboratory.