HIGH PRODUCTIVITY WITH QUALITY: EXPANSION OF THE ALUMINA REFINERY AT CVG-INTERALUMINA

Escalona, S. and Murgia, P.

CVG-Interalumina has completed by February 1992 an expansion project to increase its production rate from 1.3 to 2.0 MTPY alumina, without significantly increasing liquor flows and mainly by increasing the precipitation yields above 80 g Al2O3 per litre of mother liquor while maintaining consistent good quality of the alumina.

This has been achieved by the introduction of the Alusuisse Precipitation Process, state of the art process equipment and a particular hydrate classification arrangement where hydrocyclones and gravity settlers have been combined to provide a four fold classification. These and other process features will allow better control of the agglomeration of hydrate in the precipitation process this being the key process point for optimizing quality parameters like granulometry and occluded soda of the product.

This paper presents an overview of the process and the experience so far gained, highlighting the process innovations regarding the higher productivities and product quality control.