Mining and mineral processing industries throughout the world rely on the efficient transportation of bulk solid. Belt conveyors have been used for the transportation of bulk solid over relatively short distances for many years, but with significant developments in analytical procedures to describe the dynamic properties of belt conveying systems, the utilisation of belt conveyors for long distance overiand transportation is becoming more economically viable. Belt conveyor installations are becoming progressively longer and belt speeds significantly faster, and as these trends continue it becomes increasingly important that the motion resistances associated with the operation of belt conveyors be minimised for optimum performance and efficiency. In the energy conscious world in which we live, no longer is it acceptable for a belt conveyor to simply transport bulk solid from one point to another, the operation must be economically viable, environmentally friendly and energy efficient. The energy consumed in raising bulk solid from one level to another is typically a parameter that cannot be easily changed, and is usually determined by plant constraints or the terrain over which the conveyor is travelling. As a result the primary area of focus in order to minimise power consumption is the resistances associated with the motion of the belt conveyor. The energy consumed during the operation of a long horizontal belt conveyor is primarily due to the frictional resistance that occurs along the length of the conveyor. This resistance is known as the main resistance and includes the belt and bulk solid flexure resistance, the rotating resistance of the idler rolls and the indentation rolling resistance of the conveyor belt. This paper will discuss each component of the main resistance and provide details of methods to calculate the contribution of each component. A finite difference solution that applies orthotropic plate mechanics is described to calculate the deflection of the conveyor belt due to the loading induced from the weight of the belt and bulk solid, and the loading induced from the relative movement of the bulk solid. Given the displacement of the belt and bulk solid the flexure resistance of each component can then be calculated. The rotating resistance of the idler rolls is briefly discussed and an apparatus to measure the resistance is presented. A finite element model is then discussed which calculates the indentation rolling resistance occurring at each idler set from the viscoelastic properties of the bottom cover of the conveyor belt.
BELTCON 12: International Materials Handling Conference 2003. BELTCON 12 Papers (Johannesburg, South Africa 23-24 July, 2003)