Analysing DSM opportunities on mine conveyor systems

Abstract

The demand for electricity around the globe is increasing at an alarming rate. South Africa is no exception with electricity demand that has increased to a point where it is close to the maximum available capacity. Most of the South African electricity consumers have already experienced supply shortages where the possibility of frequent load shedding has became part of their normal lives. A big concern in the supply of electricity is the peak loads that are created by domestic users. These peak loads occur from 07:00 to 10:00 and again from 18:00 to 20:00. Load-shifting, which is part of Eskom's Demand Side Management (DSM) program, is aimed at reducing the demand for electricity during the two peak time periods. The conveyor systems at coalmines in South Africa were studied to identify possible load-shifting interventions. These mines make use of long conveyor belts to transfer the coal from mining sections to surface bunkers. Some of these conveyor systems have installed electrical capacities of more than 15,000 kW. One of the biggest constraints that were identified for these systems was the possible influence of load-shifting on production at the mining sections. This constraint was addressed by the use of simulation models that predict the bunker levels for different conveyor belt schedules and production inputs. The load-shifting capabilities of the conveyor systems were analysed using these simulation models. The simulation models proved that it would be possible to implement load-shifting on the conveyor systems with a maximum potential of 3,600 kW during the evening peak at one of the mines that was considered. The estimated electrical cost savings for such an intervention is R 529,000 per annum. There is thus a possibility to reduce electrical load during Eskom peak times by implementing load-shifting techniques on conveyor systems.