Dragline overburden stripping designs in alluvial gold mining

A methodology for calculating parameters of direct dumping flowsheets for peat stripping by draglines is proposed. The methodology includes the following fundamental principles: removal of peat from each stripping cut to the final position of the dump; dumping of peat in several dragline travels (axes); inclusion of the main occurrence parameters of a placer (overburden thickness, cross-section width, slope angles); selection of cross-section shape of a dump (triangular or trapezoidal); operation of dragline at the pre-dump positon; interval change in the width of cuts; calculation per one meter of length of a dredging site to create initial data base on variation in the structural parameters of the placer by exploration drilling lines. The following sequence of parameters is proposed for the calculation within a peat stripping design: total volume of peat overburden; volume of peat overburden that can be placed on the side of a placer without re-handling; volume of peat that needs re-handling; number of cuts; width of cuts; width of the dumping area; distance of peat removal from the initial stripping cut to the final dump; distance between travel axes of a dragline; number of travel axes; re-handling coefficients; layout of dragline travel axes; determination of boundary conditions for re-handling by digging radius; radius of unloading; digging depth; height of unloading. The procedure also takes into account both the width of a safety berm between the dragline center and overburden bench edge, and the process variables of a dragline such as the digging depth, unloading height, and the digging and unloading radii.