Feed processing for improved alumina process performance

US6582670B1 · kind B1 · utility

Assignee

• Comalco Aluminum Limited · AU

Inventors

• Michael John Hollitt · Melbourne, AU
• Stephen Charles Grocott · Calle de la Era, AU
• John Peter Kisler · Ballarat, AU
• Colin John Beeby · Melbourne, AU

Key dates

• Filing date: Jun 18, 2001
• Grant date: Jun 24, 2003
• Expiry date: Jun 18, 2021

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C22B21/0007
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A process is provided for the treatment of an alumina process feedstock prior to transferring the treated feedstock to an alumina process for extracting refined alumina from the treated feedstock. The treatment process includes: (a) heating the alumina process feedstock to a temperature of 400° C. to 650° C. by direct contact with combustion gas, and (b) cooling the heated feedstock to a temperature at which it can be handled and fed to the alumina process. The treatment process also includes controlling the contact time of the alumina process feedstock at temperatures in step (a) to ensure decomposition of alumina trihydrate and alumina monohydrate. The process also includes: (i) limiting the maximum temperature of incoming gas to a stage of the process in which the alumina process feedstock reaches the above temperature range of 400° C. to 650° C. (which is to be considered to be the highest temperature stage, and/or (ii) limiting the heat input into the highest temperature stage by ensuring that the main thermal load associated with thermal dehydration of the alumina process feedstock is taken up in earlier stage or stages into which combustion gas, at a temperat…