Clegg, R.L., Boily, H., Boulanger, C., and Parent, L.

ESP dust is normally less than 20 µm. This size fraction in metallurgical alumina has been shown to contribute to dust emissions at smelters, particularly in wet-scrubbed smelters. Some smelters have also claimed an increase in electric current efficiency from a reduction in %-20 µm in their alumina feed. A process was developed in the laboratories of Alcan International Ltd. in Jonquière to granulate ESP dust. Using this process 25 t of granules were used as a portion of the feed in a flash calciner and in a smelter pot. These tests were successful, but the process equipment used was inadequate for a full scale, fully automated production of ESP dust granules. This paper describes the development of a fully automated, prototype agglomeration unit at Alcan's Vaudreuil Works' alumina Calcination Centre.