WIO-MFAおよびSFAによる我が国の鉄資源循環とマンガンフロー分析

抄録

  Scrap recycling is subject to some problems, such as unstable supply conditions and contamination by impurities. One of the main reasons is that many industrial products with advanced functions are equipped with circuit boards, motors and wiring harnesses, which contain many kinds of metals, such as copper, lead, and zinc. Their presence is likely to result in the contamination of iron scrap with impurities when end-of-life vehicles or home appliances are reused as steel resources.
  The second main reason is the significant increase in the demand for special steel, such as stainless steel, high-tensile steel, and high-manganese steel. The fact that iron scrap coming from these products contains high ratios of manganese, nickel, or chromium can cause problems in electric furnaces and iron casting production process, where scrap is used as major iron resources.
  Owing to its huge volume, steel materials in our society play an important role not only as a major future source of iron, but as a carrier of accompanying elements as well. From the view point of efficient management of rare resources, it is of importance to understand the flow of accompanying elements that are associated with the flow of iron and steel materials.
  We have surveyed the current situation of the generation and recycling of iron and steel scrap in Japan, and analyzed the usage of steel scrap in each category of steel products quantitatively based on iron and steel statistics. Furthermore, the possible effects of the diffusion of rare metals in iron scrap, and its effects on the efficiency of steel production were examined by scenario analysis based on Waste Input Output model (WIO-MFA). The results indicate the importance of sorting scrap on the basis of the composition of alloying elements.