Impact of the recovery of secondary ferrous materials from alternative ELV treatment methods on CO2 emission: A waste input output analysis

The demand for iron and steel materials has been increasing mainly because of the rapid economic growth of the BRIC countries. The annual worldwide production of crude steel is approximately 2 billion tons. There has been a corresponding increase in the production of crude steel in Japan. As a result, the significance of Japan as a source of iron and steel scraps has also increased.1) Scrap recycling, however, is subject to some problems, such as unstable supply conditions and contamination by impurities.2) A significant part of these problems can be attributed to the increasing use of electric devices, such as circuit boards, motors, and wiring harnesses, in high-tech products. These electric devices/ equipments contain many kinds of metals, such as copper, lead, and zinc, which can become a source of contamination of steel scrap recovered from end-of-life vehicles (ELVs) or home appliances. Here the contamination of tramp elements was analyzed using a Waste Input Output model, considering the following points: (1) the amount of ferrous scrap usage in iron and steel production process, (2) copper elimination from ELV scraps, and (3) contamination of copper in iron and steel products. The results of scenario analysis indicated that copper contamination in crude steel production associated with the use of scrap from ELVs could be reduced by 2% by the use of a more recycle-oriented ELV treatment. The effects of copper elimination on CO2 emission were more significant for ordinary steel production than special steel production.