ALUMINA QUALITY: SMELTERS EXPERIENCE WITH FLUCTUATING AND OUT OF BOUND ALUMINA: POINT FEEDING AND SIDE BREAK TECHNOLOGIES. TECHNICAL, ENVIRONMENTAL AND OTHER COSTS TO A SMELTER WHEN USING OUT OF SPECIFICATIONS ALUMINA

Allais, B.

Alumina supplied to a smelter is required to be within a supplier/customer specification. A review of smelters' experience in using alumina with fluctuating and/or out of bound characteristics is presented. In particular, the impact of LOI, BET, alpha content, particle size, Na2O content and oxide impurities are examined.

The nature of the electrolysis process and the alumina feeding technologies developed so far makes centered and controlled physical and chemical alumina characteristics essential for optimal performances.

The phenomena at play and their consequences are explained and the costs to the smelter are then estimated for both point feeding and side break technologies.

Finally the specifications required are presented.