Mining industry process upgrades to reduce energy intensity while improving end product quality

In an environment of constantly cyclical mineral market prices, operators of sites in the global mining industry are challenged to continuously improve processes in order 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 both serving as a means of offsetting rising energy costs and reducing emissions to reduce environmental footprint are compelling. This paper is a case study of one such energy efficiency project recently implemented at a coal prep plant in Western Canada. The project began with a coal dryer energy efficiency feasibility study performed by a global energy services engineering company. Solicitation for the feasibility study was supported by the local utility company serving the mine site, who actually funded the cost of the study. The paper will review the analysis methods used and recommendations included in the study, followed by site implementation of one of the key study deliverables, a proposed plan to install a 6000Hp medium-voltage adjustable frequency drive to improve control of the main coal dryer exhaust fan. The paper will also describe the unique adjustable frequency drive selected for installation for this load, including an overview of the power electronics topology and resulting performance both in delivering improved energy efficiency and also process improvements. This upgrade ultimately assured both that energy and operational costs were reduced while the coal prep plant delivered a superior end-product to its customers.