Effectiveness of Continuous Surface Mining Systems: Lessons Learned from Six Decades of Lignite Extraction in Western Macedonia, Greece

The South Field Mine, situated in Western Macedonia, Greece, has used continuous surface mining systems: bucket wheel excavators (BWEs), belt conveyors, and stackers for over four decades of uninterrupted operation. This paper, using the principles of the Lessons-Learned process, tries to identify, document, analyse, and disseminate valuable knowledge and experience acquired in this mine, focusing on the performance indicators and downtimes of BWEs. Quantitative analysis methods were employed to analyse data and detect trends and factors for productive time losses. During a rather crucial period for the mine, due to decarbonisation and energy transition policies, the performance of BWEs exhibited a decline. On the other hand, availability and utilisation remained relatively stable. Mechanical failures and annual maintenance appeared to be the primary causes of downtimes. Non-operating time, connected with the lack of personnel, also had a great impact on operational efficiency. According to the linear regression model, this downtime has the greatest influence on the availability of the BWEs. In conclusion, this research implies the importance of the incorporation of new technologies for monitoring and producing daily and monthly records of the mine activities, which can enhance the overall effectiveness of a continuous mining system.