Towards “zero waste” extraction of nickel from scrap nickel-based superalloy using magnesium

Release time:2021-02-25

DOI number:10.1016/j.jclepro.2020.121275

Affiliation of Author(s):Central South University

Journal:Journal of Cleaner Production

Abstract:The rigorously environmental requirements promote to develop new processes with short and clean technical routes for recycling nickel (Ni) from superalloy. In this paper, melting magnesium was used as the extraction medium to extract nickel from nickel-based superalloy. The effect of the heating temperature, the heating time, and the mass ratio of alloy to magnesium on the extraction of metals in the alloy were investigated. An extraction rate of 97.2% for nickel and 9.8% for iron, but very low extraction rate of chromium (Cr)and the refractory metals (niobium (Nb), molybdenum (Mo), and titanium (Ti)) were obtained under the optimal conditions of the heating temperature of 800 °C, the heating time of 240 min, and the mass ratio of alloy to magnesium of 1:5. In the extraction process, magnesium firstly corroded into superalloy and then a boundary layer was formed between melting magnesium and superalloy, and nickel in the inner region of the superalloy had to pass the boundary layer to melting Mg. The element of iron, chromium and the refractory metals (niobium, molybdenum, and titanium) were enriched in the alloy residue compared to the virgin superalloy. Vacuum treatment of the magnesium alloy reduced the concentration of magnesium but increase the concentration of nickel to 95.5 wt %, while negligible quantities (total amount <0.1 wt %) of the refractory metals (niobium, molybdenum, and titanium) were obtained. Moreover, the yield colling volatile of magnesium had a purity of 99.99 wt %. Therefore, the proposed process could be a short and environmental recycling process that can recover nickel from superalloy scraps without the consumption of magnesium or the generation of toxic wastewater.

Indexed by:Journal paper

Discipline:Engineering

First-Level Discipline:Metallurgical Engineering

Document Type:J

Volume:262

Page Number:121275

Translation or Not:no

Date of Publication:2020-03-01

Included Journals:SCI