Recovery of zinc and iron from hot-dip galvanizing spent pickle liquor using solvent extraction

•An integrated and eco-friendly craft to solvent extraction and separation of Zn/Fe from spent pickle liquor is presented.•Extracting 99.99% zinc by a three-stage counter current extraction obtained by the McCabe-Thiele diagram.•The formation and migration of metal ions in the spent pickle liquor were evaluated by visual minted simulation software.•The structure of extractant and extraction complex were optimized by DFT to verify the experiment and characterization.•Waste minimization is achieved according to a “dischargeable” strategy.