How pure is zinc produced by the electrolytic process?

Zinc produced by the electrolytic process typically reaches a purity of 99.99 percent or more.1

Achieving this high level of purity is a critical necessity of the process, as the presence of even trace amounts of certain metallic impurities—such as copper, nickel, cadmium, cobalt, and germanium—can interfere with the deposition of zinc at the cathode. To ensure this quality, the electrolyte undergoes an extreme two-stage purification process: first, the removal of iron as a solid residue (such as jarosite, goethite, or hematite), followed by cementation with zinc dust to eliminate other metallic contaminants. After the zinc is deposited on the aluminum cathodes, it is stripped and remelted in an induction furnace before being cast into its final form.1