Purification and Recovery of Hot-Dip Galvanizing Slag via Supergravity-Induced Cake-Mode Filtration

Abstract

The elimination and retrieval of slag produced during the hot-dip galvanizing process are crucial in reducing plating defects and enhancing economic efficiency. Hot-dip galvanizing slag can be separated and purified efficiently by using graphite carbon felt filtration in a supergravity field. The effects of the gravity coefficient (G), separation temperature (T), and separation time (t) on the separation efficiency were investigated. Under the optimal conditions as G = 300, T = 460 °C, and t = 120 s, these conditions yielded filtered zinc with 0.022 wt% Fe and 1.097 wt% Al. The separation efficiencies achieved were 87% for the acquisition ratio of filtered zinc (AZn), 93.67% for the recovery ratio of zinc (RZn), and 96.01% for the loss ratio of iron (LFe). Based on these laboratory findings, an amplified centrifugal separation apparatus was conceptually designed for future online separation and recycle of zinc slag on an engineering scale. The filtered zinc obtained from this apparatus contained 0.027 wt% Fe and 1.844 wt% Al, while the recovery ratio of zinc (RZn) and the loss ratio of iron (LFe) achieved 85.97% and 95.47%, respectively.