Mechanism and application of seed-induced goethite crystal growth for iron removal from rich-zinc solution

The goethite residue generated from zinc hydrometallurgy is classified as hazardous solid waste, produced in large quantities, and results in significant zinc loss. The study was conducted on removing iron from FeSO 4 -ZnSO 4 solution, employing seed-induced nucleation methods. Analysis of the iron removal rate, residue structure, morphology, and elemental composition involved ICP, XRD, FT-IR, and SEM. The existing state of zinc was investigated by combining step-by-step dissolution using hydrochloric acid. Concurrently, iron removal tests were extended to industrial solutions to assess the influence of seeds and solution pH on zinc loss and residue yield. The results revealed that seed addition increased the iron removal rate by 3%, elevated the residual iron content by 6.39%, and mitigated zinc loss by 29.55% in the simulated solution. Seed-induced nucleation prevented excessive nuclei formation, fostering crystal stable growth and high crystallinity. In addition, the zinc content of surface adsorption and crystal internal embedding in the residue was determined, and the zinc distribution on the surface was dense. In contrast, the total amount of zinc within the crystal was higher. The test results in the industrial solution demonstrated that the introduction of seeds expanded the pH range for goethite formation and growth, and the zinc loss per ton of iron removed was reduced by 50.91 kg (34.12%) and the iron residue reduced by 0.17 t (8.72%).