Hard zinc is a kind of zinc-based alloy as the byproduct of crude zinc smelting process (for example, ISP process), with the main element being zinc (more than 80%) and others Al, Sn, Pb, Cd, Cu, Ni, etc. Hot dip galvanizing zinc is the second major source of hard zinc. It is generated as blue sticky crystal setting at the bottom of galvanizing pot/kettle, containing lots of impurities like iron and aluminum. 

Metalcess developed zinc distillation system to treat hard zinc.

Hard zinc from zinc smelting process is used to separate zinc (≥99.996%) from residue (≤2% zinc content) by distillation technology, and recover valuable metal from the residue.

Hard zinc from Hot dip galvanizing zinc process is used to separate zinc from iron and aluminium and get high purity zinc (≥99.996%)/ Fe-Al alloy by distillation technology.

The system allows continuous charging and continuous distillation to eliminate oxidation to zinc due to batchwise operation and decrease the operating cost, thus it can produce high purity zinc directly. The condenser can be changed to shift between high purity zinc ingot/high purity super fine zinc powder and high purity active zinc oxide powder, flexible to meet market demands.