Optimization of parameters of open-pit screening and dumping stations

Abstract

Introduction. The mining and geological features of a number of deposits lead to the fact that during the development of the massif under the influence of drilling and blasting operations, the degree of crushing of a mineral depends on the content of useful components in it, and the chemical composition of the ore is differentiated by size classes. The determined relationship between the quality of the ore mass and its size can be used to increase the efficiency of the ore preparation technology through the use of screening and dumping stations (SDS) in open pits. The implementation of the ore preparation technology based on the SDS will allow to reduce the costs of enrichment and transportation of the ore mass by separating its substandard part directly in the open pit and excluding it from the traffic flow at the processing plant, where the efficient operation of SDS is possible by optimizing a number of parameters as mining transport equipment serving SDS and a screener itself. Results. To determine the main parameters of SDS the characteristics of the initial movement of the rock mass along the inclined surface of the screen were determined, such as the productivity of unloading the vehicle onto the surface, the initial thickness of the layer for feeding and the speed of movement of the rock mass along the slope of the screener. Based on the presented algorithm, the main characteristics of the screening process are calculated: the size of the material flow layer in the i-th screener section; the speed of movement of the bulk mass along the screener; the average size of a piece in the starting material and the output of the material into screen throughs. The parameters of the screening process were determined on the basis of a given relative content of the size class of the material supplied to the surface of the screener, subject to its uniform distribution within the class. The optimized parameters of SDS were selected: the angle of inclination of the screener and the linear dimensions of the unloading platform, depending on the dimensions of the dump truck. Determination of the optimal parameters of SDS was carried out by constructing a generalized desirability function for two optimized criteria: the material yield to screen throughs and the oversize of the screener. Based on results of the calculation, optimization graphs of the dependence of the optimization function on the angle of inclination of the surface of the screener and the carrying capacity of the dump truck unloaded onto the screener were constructed. Conclusions. The optimal angle of inclination of SDS screen is 40° –42° and does not depend on the grain size distribution of the feedstock supplied to screening.