Preparation of Al-Sc Master Alloy by Aluminothermic Reaction with Special Molten Salt

Al-Sc master alloy is prepared by aluminothermic reaction with a kind of special molten salt under the normal atmospheric condition. To achieve larger Sc recovery rate, the composition and pretreatment of the molten salt are studied. The optimum molten salt is obtained by melting together Sc₂O₃, NaF, KCl, NaCl, ScF₃ and Na₃AlF₆ mixture under a mass ratio of 3:5:10:10:2:30, followed by solidifying and crushing. The pretreated salt is added to the Aluminum melt with a mass ratio of 60:100 to prepare Al-Sc master alloy. When the residue of molten salt is reused for three times, the Sc recovery rate can reach 91%. The structure and composition of the residue are examined using X-ray diffraction (XRD) analyzer and differential scanning calorimetry (DSC) analyzer. Based on the analysis of the residue, mechanism of the aluminothermic reaction to achieve larger Sc recovery rate with this special molten salt is discussed.