One-step and selective extraction of nickel from nickel-based superalloy by molten zinc
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. National & Regional Joint Engineering Research Center of Nonferrous Metal Resources Recycling, Changsha 410083, China;
3. Hunan Key Laboratory of Nonferrous Metal Resources Recycling, Changsha 410083, China)
2. National & Regional Joint Engineering Research Center of Nonferrous Metal Resources Recycling, Changsha 410083, China;
3. Hunan Key Laboratory of Nonferrous Metal Resources Recycling, Changsha 410083, China)
Abstract: Nickel-based superalloy was treated with molten zinc for the selective extraction of nickel. The effects of heating temperature, heating time, and the mass ratio of zinc to superalloy on the extraction of metals in the superalloy were investigated. An extraction rate of 95.2% for nickel, 55.4% for iron and 30.4% for chromium, but low extraction rates of the refractory metals (titanium (Ti), molybdenum (Mo), and niobium (Nb)) were obtained under the optimal conditions of the heating temperature of 850 °C, the heating time of 4 h, and the zinc/superalloy mass ratio of 10:1. In the subsequent vacuum distillation process, the obtained nickel alloy contained nickel with a purity of 73.5 wt.% after zinc removal. Moreover, the recovered zinc after the distillation process had a purity of 99.9 wt.%. The results of the investigated process indicated the possibility of extracting nickel directly from nickel-based superalloy scraps.
Key words: superalloy; zinc; nickel; extraction; vacuum separation