Cleaner Coal: Improving Energy Efficiency at a Coal Preparation Plant in Western Canada

In an environment of constantly cyclical mineral market prices, operators of sites in the global mining industry are challenged to continuously improve processes to remain competitive with their peers. Although not necessarily a priority in the past, the issue of energy-efficiency project upgrades has moved to the forefront of mine operations. The dual benefits of serving as a means of offsetting rising energy costs and reducing emissions to reduce the environmental footprint are compelling. This article is a case study of one such energy-efficiency project recently implemented at a coal preparation plant in western Canada. The project began with a coal dryer energy efficiency feasibility study (EEFS) performed by a global energy services engineering company. Solicitation for the EEFS was supported by the local utility company serving the mine site, which funded the cost of the research. This article will review the analysis methods used and the recommendations included in the study and then describe site implementation of one of the key deliverables of the EEFS: a proposed plan to install a 6,000-hp medium-voltage adjustable frequency drive (AFD) to improve control of the main coal dryer exhaust fan. This article will also describe the unique AFD selected for installation for this load, including an overview of the power electronics topology and the resulting performance in delivering improved energy efficiency and process improvements. This upgrade ultimately ensured that energy and operational costs were reduced while the coal preparation plant delivered a superior end product to its customers.