Efficient use of energy in the ventilation and cooling of mines

Abstract

Escalating energy and electricity costs have become one of the largest drivers of expenditure in mining operations. Over the last eight years, energy costs have tripled when expressed as a percentage of total expenses in South African mines. In an effort to manage and reduce electricity costs, energy management strategies can be developed, inefficient operating units replaced, and the operation of energy-consuming components of ventilation systems optimized. Power consumption on mines is controlled mainly by three strategies, namely load clipping, by which energy use is reduced for certain parts of the day; load shifting, by which energy use is shifted to other parts of the day; and energy efficiency, by which energy use is reduced permanently. In this paper several projects that were implemented using the first two strategies of load clipping and load shifting are investigated. The actual and potential savings that can be achieved by implementing such energysaving interventions are presented. To reduce the operating costs of ventilating and cooling underground mines permanently, system optimization studies must be completed. Methods that can be used to reduce energy usage by optimizing cooling and ventilation systems are described, and network simulation models that accurately reflect the current and planned ventilation conditions are discussed. These models are then used to examine various options for improving the overall ventilation and cooling strategy. Different optimization scenarios can be simulated, and this assists the design engineer in obtaining the most energy-efficient system that will satisfy design workplace conditions. The final outcome is a reduction in operating costs, which can result in better operating margins and an extension of the life of mine.