Material Flow Analysis of Aluminum Dross and Environmental Assessment for Its Recycling Process

抄録

Approximately 400,000 tons per year of aluminum dross are generated during a melting process of aluminum metal in Japan. The Al dross and the residue, which have high concentration of metallic Al, are mostly used as an Al resource for Al production or as a deoxidizer in the steel industry. On the other hand, the lower grade residue with the Al content less than 20%, is difficult to be recycled and is therefore landfilled.
This paper deals with (1) a material flow analysis (MFA) of the domestic aluminum dross in order to achieve clear targets for recycling of aluminum dross and residue, and (2) an environmental assessment of newly developed technologies for its recycling, such as the process of hydrogen production from residue.
The result of material flow analysis on the domestic aluminum dross in 2003 shows that 234.4×10³ t of aluminum is recovered and 215.0×10³ t of residue is generated from the dross. The residue is mostly used in the steelmaking process, whereas 50.0×10³ t of residue is landfilled in the final disposal site. As the result of the environmental assessment through the material flow, there is a possibility of reduction of CO₂ emission and waste emissions by using residue (Al content: 10%) as a hydrogen resource, which is presently landfilled.