The article presents the principles of safe cutting of rocks prone to generate igniting methane sparks. A list of methane ignitions and explosions from the sparking of rocks caused by cutting with road header was given. Unusual case of methane ignition in conditions of full technical and technological protection of roadway development is discussed. In conclusions, the importance of an individual approach to geological and mining conditions in the case of the need to cut sparking rocks was emphasized.
Excavation, especially of hard rocks, using boom-type road headers is a source of strong vibrations of the boom in which they are equipped. These vibrations are transferred through construction nodes further to the turntable and the body of the road header. On the one hand, they are of great importance from the point of view of the durability and the reliability of the mining machine. On the other hand, they affect the variability of the parameters at which the process of cutting the heading face surface of a drilled roadway or tunnel is carried out. For the purpose of determining the vibration intensity of the boom of the road header a photogrammetry system based on two high-speed cameras Phantom Miro LC 120 was used. During the experimental investigations of the cutting process of a cement-sand block using the R-130 road header, the boom and turntable movements were recorded. The analysis of the time-lapse pictures of the recorded footage obtained from the high-speed cameras using dedicated TEMA 3D software allowed to determine the spatial trajectory of movement of the boom and the turntable during the cutting of the massive with specified mechanical properties with set values of the parameters of this process. Basing on the time courses of the coordinates of the boom and turntable characteristic points, the courses of the actual boom swinging speed and acceleration components of its vibrations were determined. The intensity of these vibrations was related to the conditions of the cutting process.
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