Secondary zinc
Zinc metallurgy

Most secondary zinc is produced as zinc oxide (Waelz oxide), which is recycled in primary metallurgy. Waelz oxides are mainly recycled in thermal metallurgy (Imperial smelting). However, they can also be used as a feedstock for hydrometallurgical processes.

Electric steel mill dust is a key feedstock for this recycling industry. In Europe, an estimated 45% of steel mill dust is recycled using the Waelz process. This technology is also used to treat carbonate ores.

There are other secondary zinc treatment processes, but few of them have seen significant industrial development.