IN-LINE SALT FLUXING PROCESS: THE SOLUTION TO CHLORINE GAS UTILIZATION IN CASTHOUSES

摘要

Over the past decades, the aluminium industry has been very active in developing and implementing metal treatment technologies such as the TAC and RFI to reduce the negative environmental, health and safety (EHS) impacts of gaseous chlorine. However, most casthouses are still relying on the utilization of chlorine gas for in-line metal treatment. This requires maintaining an active chlorine network at considerable costs and EHS considerations. A new technology developed at the Alcan Arvida Research and Development Centre in collaboration with la Societe des Technologies de I'Aluminium du Saguenay (STAS) was implemented at the Alcan Iceland Ltd (ISAL) casthouse. This new technology has proven successful in achieving a complete elimination of chlorine and coping with the ultimate Alcan chlorine-free casthouse objective and commitment towards sustainable development. This paper reviews the challenges to substitute chlorine gas utilization while achieving equivalent or better metallurgical performances and product quality. Preliminary metallurgical performances (hydrogen, alkali and inclusion removal) from pilot scale and industrial conditions are discussed. The new in-line salt fluxing process is described in terms of equipment and process requirements. Finally, the work of the Alcan ISAL casthouse towards total elimination of chlorine usage is presented.