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Reliability of a bucket-wheel excavator guidance system

Deligiorgis Vasileios

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Summary

The reduction of production cost and the enhancement of the mining safety are essential factors for the exploitation of the marginally mineable deposits. The advanced automation of the mining processes is considered the most promising solution to attain these goals.In this dissertation the operation of an experimental system measuring contactless the electrical conductivity of geological formations during extraction is analyzed. The experimental system was installed to a bucket-wheel excavator that is used for the excavation of the overburden of a lignite deposit. This overburden includes hard formations which are difficult to be excavated by bucket-wheel excavators and the contact of buckets with these hard formations must be avoided. The final scope is to investigate the appropriate measures for risk mitigation during the mining procedure. This is achieved with the development of a real-time guidance system for the excavator in order to avoid collision of the buckets with hard formations.For the reliability enhancement of this system, FMECA (Failure mode, effects and criticality analysis) method is used in order to detect the most vulnerable parts of the system at different phases of its life cycle. The flexibility of the method and the feature of detection are suitable for the accomplishment of this target. More specifically the method is used for the assurance of the implementation of the suitable procedure of bench face reconnaissance during the excavation, and for the determination of the appropriate excavation parameters in advance.For an accurate reliability analysis, the system and its subsystems (consisting of hardware and processes) are defined in accordance to the stages of automation. The system is serially analyzed and the analysis begins from the accurate separation of the different geologic formation attributes and ends with the consequence to the mining equipment and the excavation process. This approach is related to the term “precision mining” which is proposed mainly for the definition of this type of automation in excavation.Based on the results of the FMECA reliability analysis of the examined experimental system, it is anticipated that the corresponding industrial prototype will have better performance. The real-time consultation will aid operator to make the right decisions and the overall excavation process will be improved significantly.

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