Substance Flow Analysis of Zinc Associated with Iron and Steel Cycle in Japan, and Environmental Assessment of EAF Dust Recycling Process

Abstract

Japanese zinc production in 2005 was 6.75×10⁵ t, and domestic demand of zinc was 4.82×10⁵ t. The main use of metallic zinc is in the surface coating of steel and the metal accounts for 62.8% of the domestic demand. The purposes of this study are as follows: (1) to identify the material flow of zinc associated with steel production, and (2) to estimate the environmental effects (energy consumption and CO₂ emission reduction) of some intermediate dust treatment processes.
The major conclusions are (a) in Japan, 6.16×10⁶ t of blast furnace/converter dust was generated in 2000, and this product contained 2.20×10⁴ t-Zn. 0.433×10⁶ t of EAF dust was generated and this dust contained 8.86×10⁴ t-Zn, and (b) 9.57 MJ of energy is required for producing 1 kg of zinc oxide by the Waelz process using EAF dust, and the estimated amount of CO₂ emission in this process is 1.49 kg-CO₂. On the other hand, if the LAMS process proposed by the authors is employed, it is estimated that there will be a reduction of 1.70 MJ in energy consumption and a reduction of 0.14 kg-CO₂ in CO₂ emissions.