Abstract
CO2 emission from the zinc production by recycling of the Electric Arc Furnace dust (EAF dust) was quantitatively evaluated using Life Cycle Assessment (LCA) technique. EAF dust is used as one of the raw materials in pyrolytic zinc for the smelter. So, inventories for this study such as fuel consumption of unit process and in-house electricity were established based on literatures and the public statistical data. The analysis of Life Cycle Inventory (LCI) has been conducted and as a result, the followings have been observed.
(1) The amount of CO2 emission from the pyrolytic zinc production is about 3.4 kg / kg-zinc. 40 % of the whole CO2 emission is originated by the coke combustion in the smelting furnace. And, 20 % of the whole CO2 emission is attributable to the separation process of EAF dust.
(2) If recycling of EAF dust to pyrolytic zinc is accelerated, the amount of CO2 emission from zinc production is increased under the assumption that the energy consumption in the stabilization process of EAF dust is negligible. This is attributable to the difference of the energy consumption to convert to the roasted ore from the raw materials.
As a result, the present zinc recycling system from EAF dust has disadvantage from the viewpoint of the CO2 emission. Hence, the projected recycling systems of metal recovery in the steel industry are expected to reduce the energy consumption. However, the recycling of the EAF dust must be evaluated from not only the CO2 emission, but also impact assessment based on the resources exhaustion, the global warming, the land use and so on. Impact assessment methodology must be developed to evaluate the validity of the recycling of EAF dust.
