DUST AND DUSTINESS TESTING OF SMELTER-GRADE ALUMINA

Further evaluation of the Perra pulvimeter as a tool for measuring dustiness of smelter-grade alumina during handling operations has been undertaken. Samples tested include a suite of aluminas from Alcoa of Australia Limited and a suite provided by Alcan International Limited. A complex relationship between the superfines (-20µm) content and the dustiness index, similar to that previously noted by Authier-Martin (1989), was obtained. Dustiness index increased with superfines to some threshold value. At higher superfines levels there was often a decrease in dustiness. That change point is different for aluminas from different sources. The dusts collected in the pulvimeter cup and used as a measure of dustiness were compared with dust samples from Refineries. The pulivimeter dusts tended to contain coarse (50µm) and fine (15µm) material; Refinery dusts contained only the fine material. Various subjective ways of ranking the aluminas tested for dustiness were undertaken. Those rankings agreed well with the dustiness index values. The pulvimeter may provide a measure of the handling dustiness for aluminas. Further testing of the pulvimeter is required in order to determine the reproducibility of the measurements.

An initial look at smelter dusts was undertaken by collecting and analysing dusts from the fume system. Techniques such as laser sizing, scanning electron microscopy, x-ray diffraction and energy dispersive analysis were used. Such techniques are able to give valuable information which would be helpful in process and industrial hygiene studies.