Electric arc furnace (EAF) dust: Application of air classification for improved zinc enrichment in in-plant recycling

Currently, more than half of the electric arc furnace (EAF) dust produced worldwide is still sent to landfill. This dust contains approximately 7.0% of the world Zn production. The other half of the EAF dust is processed pyrometallurgically or hydrometallurgically to recover Zn. The processing costs for EAF dust strongly depend on the Zn concentration. Therefore, several steel mills apply in-plant enrichment of Zn by recycling part of the dust back into the furnace to reduce the specific processing cost for the EAF dust and at the same time decrease the amount of dust that has to be discharged. Separation of EAF dust into size fractions by air classification showed a distinct dependence of the Zn concentration on the particle size with an enrichment of Zn in the fine size fractions and depletion in the coarse fractions. Therefore, in in-plant dust recycling, air classification of the dust could be used to reduce the amount of recycled Zn and dust but still reaching the same Zn concentration in the discharged dust. This would reduce the energy demand for Zn volatilization in the furnace and the required capacity of the dust recycling system.