This work aims to give an overview of wireless communication technologies (WCT) for underground applications. Difficulties regarding the harsh mining environment and operational constraints for WCT implementation and use are discussed. Selected technologies are then classified regarding underground mining-specific use cases in advanced mining operations. Use-case-based application categories such as ‘automation and teleoperation’, ‘tracking and tracing’ and ‘Long-Range Underground Monitoring (LUM)’ are defined. The use cases determine requirements for the operational suitability and also quantify evaluation criteria for the evaluation of WCT. The result is a comparison by category of the wireless technologies, which underlines potentials of different technologies for defined use cases, but it can be concluded that the technology always has to be evaluated within the use case and operational constraints.

The global industrial mining sector is, like other sectors, undergoing an unprecedented transformation pushed by global sustainability and climate challenges. The need to increase productivity and efficiency of mineral extraction along with increasing pressure from a wide range of stakeholders to decarbonise the industry and make mining practices more sustainable, accountable, and socially acceptable are driving the adoption of automation and digitalisation technologies as well as the electrification of equipment and the implementation of more sustainable energy solutions for the industry. Automation and digitalisation are changing the way minerals and metals are extracted and provide important tools for designing and implementing the mine of the future: a digitally integrated, autonomous mine where no humans need to be put in harm’s way and in which the connected systems are able to reduce the ever-increasing complexity to such an extent that improved decision-making can be realised in real time. Mining as an industry still has a way to go to reach the potential of automation and digitalisation on the one hand, and alternative drive systems and sustainable power generation on the other. This paper will give an overview of empirically derived leading technologies underlying the current transformation and will place them in the context of the data-information-value-chain that can provide a more systematic approach to describe the various technologies and, in particular, their interrelationships. This can support a better understanding of assessing the overall technological maturity of an operation, especially with respect to their evolution from automation of equipment towards autonomous systems. There is no reason to doubt that, from a technology perspective, the digitally connected, autonomous, and carbon-free mine have the potential to become a reality. Breakthrough effects can be expected to come not from any single technology but rather from successfully developing, implementing, and integrating the full suite of (available) automation and digitalisation technologies across entire mining operations and moving towards digitally integrated, autonomous systems considering the process and its interrelations holistically (Clausen et al. 2020b). However, in order to get there, mining companies need to consider not only the technological aspects of this transformation. For successfully responding to the changing landscape of stakeholder expectations and future-proofing the industry requires, the authors argue that mining companies need to adopt a mind-set of the human-centred climate smart mine (Clausen and Sörensen 2021). In addition, mining companies need to reconsider their role in the economic, social, and environmental ecosystem they are embedded in so they can break through traditions that keep them from successfully positioning themselves as builders of social value.

The analysis of vibrations and acoustic emissions (AE) are two recognized non-destructive techniques used for machine fault diagnosis. In recent years, the two techniques have been comparatively evaluated by different researchers with experimental tests. Several evaluations have shown that the AE analysis has a higher potential than the vibration analysis for fault diagnosis of mechanical components for certain cases. However, the distance between the AE sensor and the fault is an important factor that can considerably decrease the potential to detect damage and that has not been sufficiently investigated. Moreover, the comparisons have not yet addressed conditions of slow speed that for example are usual for wind turbine gearboxes. Therefore, in this paper we present two comparative case studies that address both topics. Both case studies consider planetary gearboxes with faults in their ring gears. The first case study corresponds to a small planetary gearbox in which the AE and vibration sensors were installed together at two different positions. The second case study corresponds to a full-size wind turbine gearbox in which three pairs of AE and vibration sensors were installed on the outside of the ring gear from a low-speed planetary stage. The results of the evaluations demonstrate the important influence of the distance between sensors and fault. Despite this, the good results from the AE analysis indicate that this technique should be considered as an important complement to the traditional vibration analysis. The main contribution of this paper is comparing AE and vibration analysis by using not only experimental data from a small planetary gearbox but also from a full-size wind turbine gearbox. The comparison addresses the topics of proximity of the sensor to the fault and low-speed conditions.

As indoor positioning provides particular challenges due to the unavailability of GPS signals, various systems such as ultra-wideband (UWB), radio frequency identification (RFID), ultrasound, and wireless local area network (WLAN) have been proposed in recent years. Some of these technologies are currently being marketed and some are still being developed. UWB technology allows for higher precision while also reducing power consumption. Hence, the underground automation and localization systems can use this technology for more accuracy and robustness. This article discusses new robust UWB modules used for underground positioning and collision avoidance with regard to human safety in underground mining operations.

Suspended monorails are a common mode of transportation for materials and personnel in underground mines. The goal of the EU-funded project “Innovative High Efficiency Power System for Machines and Devices, Increasing the Level of Work Safety in Underground Mining Excavations (HEETII)” is to introduce a single-wire energy transmission system combined with a capacitive-coupling-based wireless transmission system to power the suspended tractor, along with a monitoring system that will monitor the energy network and additional environmental parameters of the mine. Additionally, the monitoring system acts as the wireless communication backbone, allowing for data transmission to surface headquarters, where the data are processed and logged in a central database. This enables operators to detect and take preemptive measures to prevent potential hazards in the mine, improving the overall efficiency of the energy transmission system. This paper describes the additional considerations required for electrical systems in underground mines with potentially explosive atmospheres, as well as the design of the energy transmission system and the monitoring system.