Study of Ni-Impurity Removal from Al Melt

Impurity control in the production of Al alloys is very important for achieving desired alloy properties. There has been an increasing impurity concentration (particularly nickel and vanadium) in the coke used in the primary Al production which ends up in the Al alloys. V can be removed in the casthouse through boron treatment. Ni, however, is a non-reactive element and difficult to be remove. There is currently no technique available in the casthouse to remove Ni. The current paper describes an exploratory study of Ni removal from Al melt. A literature review on the available techniques for the removal of Ni impurity from Al melt was carried out; followed by a systematic thermodynamic analysis of various Al-Ni-X systems for possible formation of Ni-containing phases in Al melt. Laboratory experiments were carried out to test the possible systems identified from the thermodynamic analysis.