Development of a new attrition index using single impact

Alumina breakage is a significant problem for alumina producers. Weak alumina tends to result in difficulties in materials handling, excess loss of product and environmental issues. Alumina strength is currently measured, as it has been for many years reported as Attrition Index using the Forsythe technique and apparatus. However this test suffers from a number of drawbacks, the main one being that by only considering the change in < 45 m , it falsely reports as strong alumina a weak alumina with a coarse size distribution. A project to examine an alternative method for determining alumina strength based on single particle impact is underway with Central Queensland University’s PELM (Process Engineering and Light Metals) Centre, Gladstone. An apparatus similar to that developed by Ghadiri (University of Surrey, UK) has been constructed with ease of construction and use in mind. The principle of the apparatus is to accelerate alumina particles using the vacuum of a small chamber in which a target is positioned. Each particle impacts the target once (as the name suggest) and either breaks or survives the impact. After the whole sample has passed through the apparatus, both the initial and impacted sample are analysed to determine the extent of breakage. Results will be presented of a series of aluminas from several locations, corresponding to different morphology types. Breakage will be compared with the current technique according to the ranking of strong or weak product.