The geometric shape of the transported material batches in the vertical branch of a belt conveyor

Abstract

Transport above the limit angle of transport inclination provided using belt conveyors can be done in several ways. If we omit the methods based on an increase in the contact force of the transported material in relation to the surface of the conveyors belt and increase in the coefficient of friction, we will focus only on the method based on the principle of preventing the movement of the transported grains on the surface of the conveyors belt. This principle uses transverse cleats that prevent the movement (sliding or rotation) of material grains along the entire length of the conveyor belt, which is inclined at a high angle to the horizontal plane. Material grains are transported on the surface of a conveyor with cleats, distributed with a regular spacing along the entire length of the endless loop of the conveyor belt. To prevent material grains from falling of such a belt, corrugated sidewalls are fitted on both edges of the conveyor belt. This paper describes two variants that take into account the mutual position of the cleats in relation to the corrugated sidewalls. For each of the variant, the relationship is given with which it is possible to analytically quantify the volume of the bulk loose material batch that is spread over the area of the cleat in the vertical section of this conveyor belt design. The results of the measured values concerning the height of the loose material pile that were taken using laboratory instruments are listed in the tables and compared with the theoretically calculated values. Key data that must be known to calculate the pile height, and the volume of the transported material batch represent the exact value of the angle of repose for the loose material. The angle of repose of a particular loose material does not acquire a constant size, as it changes from its maximum (static angle of repose) depending on the shaking, flattening or absorbing liquid to its minimum (surcharge angle). The paper presents geometric shapes of batches for the transported material used for both limit values of the angle of repose.