A dragline simulation model for strip mine design and development

During recent years, the Australian coal industry has increasingly used large walking draglines as the dominant waste removal equipment in open cut coal mines. Because of the nature of the coal formations, dragline operations in Australian coal mining situations are quite complex and draglines are frequently used in applications beyond their normal capabilities. With the current trend to increasing dragline sizes in most of the Australian coal mines, the draglines become the highest capital investment item in these mines. It is therefore necessary to give detailed attention to the optimising operating procedures of the dragline. Dragline productivity and its stripping capabilities are directly affected by the selection of digging method, strip layout and pit geometry. Every mine has a unique combination of geological conditions. The operating methods that work well at one mine may not necessarily work at another site. Selection of an optimal stripping method, strip layout and pit geometry for a given dragline must be considered with respect to the geological conditions of the mines. With increasing geological complexity of Australian strip mines, it is becoming more important to use sophisticated techniques such as computerised mine planning methods to assist in optimising the dragline operations. A computerised dragline simulation model (CADSIM) has been developed for use in selection of optimum strategies for a dragline operation. The procedure developed links with a geological ore body model to develop a geological database for simulation. CADSIM model can be used in selection the most cost effective dragline digging method. A specific simulation language, "DSLX", was used to program seven common and innovative dragline methods currently used in Australian open cut mines. The DSLX language uses predefined functions to build strip geometry, working benches, blast profiles and spoil piles. The outputs from CADSIM model in form of volumetric, swing angles and hoist distances data were then aggregated with dragline specifications and site time study data to compare productivity and costs of the selected digging methods. The results of two case studies showed that this procedure lends itself to the "optimum" solution for dragline mine planning and design problems for a given coal deposit.