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.