Experience of using hydraulic excavators in difficult mining, geological and climatic conditions

Abstract

The article summarizes the experience of using hydraulic excavators in coal, diamondiferous and other mining operations. It is noted that the excavation capacity of modern hydraulic excavators is several times higher than that of the mechanical shovels, and the hydraulic equipment is more suitable for non-explosive excavation in hard grounds, including halfrock formations. It is shown that even in difficult mining, geological and climatic conditions in coal, diamondiferous and other mines, the use of hydraulic excavators in Russian mining companies is justified by high efficiency and high availability ratio equal to the international indicators, which are not lower than those achieved in much more favorable conditions. Research performed in industrial settings made it possible to determine the hydraulic drive's service mode and regulations, as well as rational operating conditions. Operating systems were developed with heated working fluids to compensate for the changing viscosity at low atmospheric temperatures. Based on the tests performed in Russia and abroad, blast-free excavation using hydraulic excavators is done with limited capacity (up to 400 m3/h), and the operating weight of the machines must be not less than 300 tons. The main factors, typical for operation of the open-pit hydraulic excavators include the high annual production time, high forces and dynamics (up to 70 kN per 1 m3 of the bucket capacity) in the digging mode of the unit working at the face, high specific capacity and remoteness from the outside infrastructure used for repairs of the hydraulic components. In the course of testing the hydraulic excavators, the boundary values of the face slope angle depending on the ambient temperature were established. It was experimentally proved that at top to bottom layer-by-layer excavation with the H-285S hydraulic shovel the face height can reach up to 25 m at the rated digging height of 16 m. The average lump size (not more than 300 mm) of the rock mass in a 19 m3 bucket was determined with the permissible oversize in the face up to 2,500 mm. With the normal maintenance quality, the weighted average cost of operation for electromechanical excavators and the corresponding figures for hydraulic excavators are at a comparable level.