Abstract
Open pit coal mining enterprises are constantly faced with the task of increasing the economic efficiency of mining, reducing coal losses and increasing profitability. One of the ways to increase the efficiency of open-pit mining is the improvement of the technology for developing coal-bearing zones of quarry fields in sloped and steeply complex (hard-structured) deposits. Currently, projects for promising deposits have been completed, and a number of existing sections are developing coal-bearing zones across their entire width in horizontal layers. Extraction and loading equipment for stripping and winning operations in this area is characterized by a wide variety: rope shovels (also called power or stripping shovels), backhoes and hydraulic shovels or their joint work. When using only rope shovels or only backhoes, they produce an excavation of both interbeds and coal seams. When they work together in the coal-bearing zone, the rope shovel makes a stripping of the interbeds, and the backhoe – an extraction of the coal seams. However, such technical solutions are not sufficiently substantiated. The fact is that rope shovels and backhoe shovels have their advantages and disadvantages in operation.
Highlights
Power shovels are constructively designed for the bulk excavation of all lithotypes of rocks
The features of each of these options are as follows: - each of these cargo flows has its own completeness of mechanization – on the excavation of rock, transportation and dumping (Fig. 1-a), - each of these cargo flows has a common excavation and loading, but different transport and dump equipment. This option is more often adopted in the open pits projects (Fig. 2)
Given these differences in strengths and weaknesses, it is advisable to organize the development of coal-bearing zones with a certain ratio of the volumes performed by power shovels and backhoes, providing the best technical and economic indicators
Summary
Power shovels are constructively designed for the bulk excavation of all lithotypes of rocks. The design of the mechanical part and the formed trajectory of the bucket teeth provide a low cycle time (28-32 s) for all types of power shovels, which predetermines their high performance and durability. In the conditions of excavation of complex (hard-structured) coal seams of low and medium thickness, the trajectory of the cutting edge of the bucket teeth does not correspond to the conditions of coal seams excavation, which leads to large losses of coal (up to 20%). A qualitative comparative analysis of power shovels and backhoes showed that power shovels should be used when performing large rock volumes in thick interbeds in the coal-. Excavators are highly productive, reliable and durable
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