Advanced industrial-scale recycling of nickel waste alloys: a driver for circular economy objectives

An eco-friendly electrochemical method of nickel alloy waste leaching was developed for circular economy. The nickel concentration was 72.11 g/L in 100 g/L HCl after 90 A·h, 60 °C and 5 A/dm2 current, while 37.37 g/L nickel was obtained in 100 g/L H₂SO₄ under these conditions. The energy intake was 7.5 kWh/kg Ni; a potential of 60%–70% reduction in the thermal energy need compared with pyrometallurgical routes. The elemental analyses showed favoured dissolution of Ni, Co, Cr and Fe into the solution, while refractory metals gathered in the anodic sludge, comprising 40.33–57.13 wt.% W along with Nb, Hf and Ti oxides. The recycling of nickel was 72.11 g/L, while other metals were 40.33–57.13 wt.% W, 4–5 wt.% Nb and 4–5 wt.% Hf. Briefly, the developed process allowed lumpy alloy waste treatment without grinding and provided an energy-efficient, promising and industrially viable approach for the circular recovery of nickel and precious metals.