Effect of Pre-desilication Temperature and Time on Desilication Behavior of Indian West Coast Bauxites

摘要

Desilication of Bayer liquor is a very important process step in achieving acceptable levels of silica content in liquor to precipitation in order to minimise process scaling issues and to produce alumina of acceptable quality.Pre-desilication-holding bauxite slurry at elevated temperatures prior to digestion-is a common process step being followed by many alumina refineries.Hindalco's Belgaum alumina refinery processes bauxite of different quality available from the mines of Indian West Coast.The conditions of pre-desilication like temperature and time of holding required for optimum desilication depend very much on the quality of bauxite.This study identifies the optimum process conditions to be followed by the refinery through statistically-designed laboratory experiments for various bauxites containing low to high levels of silica.Relative effects of process variables are enumerated.Similar studies are recommended for other bauxites which would help the design engineers to design the desilication process of a new refinery and the process engineers to operate an existing refinery in an optimum manner.