An Experimental Study of the Wear at Hopper Walls

Abstract

In this paper we describe experiments in which the equivalent of 100 tonnes of abrasive sand have been passed through a pilot-scale wedge-shaped hopper of half angle 10° and outlet width 1 em. The walls were then cut up and the change in wall thickness accurately measured. The rate of wear was found to be greatest at the outlet. In interpreting these results, we used the simple abrasive model for wear recommended by Johanson and Royal [1]. In this model, the rate of wear is simply proportional to both the force on a particle pressing on the wall and the speed with which it scrapes down that wall. In order to calculate these parameters, we used a measurement of the velocity in a granular material at the wall of the hopper and a prediction for the stress which is a modification of the well-known method of Janssen. The constant of proportionality (the wear coefficient) for the model was measured in a pin-on-disc experiment. A prediction for the wear profile was thus obtained which shows reasonable (within a factor of two) agreement with experiment. The apparent success of the pin-on-disc method of measuring the wear coefficient suggests that it can be used instead of the more expensive methods advocated by others. © 1995, Hosokawa Powder Technology Foundation. All rights reserved.