Belt Positioning and Skewing Prevention in Lignite Mining Using Long-Wavelength Infrared Cameras

Abstract

In open pit mines, one of the key aspects of automation is the transport of the mined minerals. Due to their economic benefit, conveyor belts are used to transport masses continuously. High availabilities and safe working conditions can be achieved by automating the process. Especially the feeding of the conveyor system has a strong automation potential. At the moment, the positioning of transfer booms or transfer chutes is done manually by a machine operator. The decisions of the operator are driven by his experience and his visual perception. The visual perception is often limited, e.g. by low light (in the evenings or at night), blinding by the sun or other environmental conditions such as dust or rain which can be present in open pit mining. This can lead to sub-optimal loading of the material. In case of off-centered loading, the conveyor belt can start to drift away from a centered position, which is called skewing. This skewing results in increased wear and tear of the system leading to breakdowns or increased maintenance times. Additionally, the transport capacity of the conveyor belt decreases because less area can be loaded with material.

To detect skewing on conveyor belts, various systems are available on the market. The most common types of detection systems are mechanical components like switches and guide roller constructions. A second group of sensors used for skewing detection are supersonic systems. Both, mechanical and supersonic systems are not able to prevent belt skewing. These systems only detect an existing misalignment.

To be able to prevent belt misalignments, a system based on long-wavelength infrared (LWIR) cameras which monitor the loading process as well as the position of the conveyor belt is proposed by the authors. The obtained data is correlated and analyzed with regard to the position of the belt when entering the loading station, the loading process itself and the belt position when leaving the station. This data can either be used for automation or if visualized to the operator, as an assistance system. This information can be used to optimize the loading process in order to prevent skewing, or to counteract already existing drift of the conveyor belt to prevent damages on the conveyor belt or other systems.