Abstract
Relevance and Objectives. Russia is currently witnessing emergence of new coal production centers with a gradual shift toward the eastern part of the country. Stricter environmental and industrial safety regulations, as well as the need to maintain an acceptable level of cost effectiveness in the mining production, determine the need for new technical solutions and optimization of mining operations, equipment and technology. The overburden of many coal mines situated in the Far East is represented by fine-grained mantle rock, which can be easily developed by open-pit excavators when thawed. However, during the freezing season, its strength and resistance to excavation multiply, which creates a need for drilling and blasting operations. There exist various methods and equipment for the mechanical destruction of permafrost. However, when the frost penetration is quite deep in the scarp slopes, it may be difficult to prepare them for excavation without using explosives. Objectives. To design/build an efficient and compact spare equipment for a hydraulic excavator, so that it could be used to weaken the rock with the frost depth of 2.0–2.5 m by cutting slits. At the same time the machine should be designed the way to be able to cut slits in scarp slopes with curved surfaces. Findings. The paper proposes an improved scheme for weakening the surface of frozen scarp slopes using a hydraulic excavator with a combination replaceable equipment, which include a milling cutter, a thermal burner and a ripper. The frozen surface layer of a scarp slope can be weakened by cutting slits to the full depth of the frozen layer. Inclined slits are used for weakening the scarp slope, and horizontal slits made along the scarp slope are used for weakening the working platform. The initial slit is made with a cutter, and if the frozen layer goes deeper than the slit made with the cutter, a thermal burner is used to produce a thermal impact on the remaining frozen layer, which helps to thaw out the frozen ground. After that the ripper cuts through the thawed rock, thus weakening the frozen layer all the way through. Findings. The proposed technique and equipment for preparing the frozen scarp slopes for excavation help optimise the open mining operations in the winter time, bring down the mining cost and lessen the environmental impact.
Keywords
Overburden works, scarp slope, permafrost, slitting, hydraulic excavator, milling tool, thermal burner.
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