Dissolution Behavior of Al₂O₃ Inclusions in CaO-Al₂O₃ Based Slag Representing Aluminothermic Reduction Slag

Abstract

In the preparation of CuCr alloy using the self-propagating high-temperature synthesis (SHS)-metallurgy method, the dissolution of alumina in molten slag has an important influence in two key steps: aluminum thermal reduction and slag refining. In the present work, the dissolution behavior of Al2O3 into molten SHS-metallurgical slags was investigated by employing the rotating cylinder method and static dissolution method. It is concluded that the increase of MgO, CaF2, CaO, and Na3AlF6 contents can increase the dissolution rate of alumina in SHS-metallurgical slag, and the order of influence is from strong to weak. Both temperature and rotating speed can increase the dissolution rate, and the rate-limiting step is the diffusion of alumina in the boundary layer, with the solid alumina first reacting with lime to form two intermediate phases, CaO·2Al2O3 and CaO·6Al2O3, and finally dissolving into the slag in the form of an aluminum polymer.

Keywords

• Al₂O₃ dissolution behavior
• aluminate slag
• intermediate compounds