Attrition index : a measure for environmental pollution caused by alumina

Aluminium is a bluish or silvery white chemical element from the boron group. In the aluminium industry, the quality of alumina, aluminium ore are commonly assessed on the basis of an important parameter called attrition index (Yang, 2003). Attrition index indicates / signifies chipping affinity of minerals under impact. The attrition index attempts to quantify the tendency of the alumina to break down during handling and produce fines. Alumina particle with a poor attrition index produces more dust, leading to loss of product and environmental pollution during handling and leads to problems in alumina smelters. Attrition property of a particle depends upon its physical, mechanical, metallurgical and chemical properties. Attrition is affected by many variables like size, shape, surface, porosity, hardness, cracks, time, velocity, pressure, shear, temperature, etc. Strength of alumina is currently measured using so called Forsythe technique. Forsythe technique involves producing a fluidized column of alumina in a standardized arrangement and measuring the change in the mass of particles <45 fl m over a set period of time.In this paper an attempt has been made to evaluate the strength of alumina based on single impact using the newly designed and built experimental rig at CQUniversity Australia. The set-up developed at CQUniversity was based on the approach used by Ghadiri and Bentham et al to evaluate the strength of paracetamol. This method used a glass tube to funnel particles towards a target for a single impact event. Once the particles leave the target material, they are collected on filter paper and sized. The particles are driven by a vacuum behind the filter (Audet & Clegg, 2008).This paper proposes to extend the work further and develop a more fundamental understanding of alumina particle breakage during single impact. The output of the research works would be helpful for alumina refineries/industries as well as for environmental agencies to understand more accurately the pollution levels caused by the refineries.