Material flow analysis on steel recycling considering accompanying substances

The demand for iron and steel materials has been increasing due mainly to the rapid economic growth of BRICs countries, with approximately 2 billion tons of crude steel being produced per year in the whole world. Under this situation, the production of crude steel in Japan is also increasing. As a result of this, the significance as an iron source of iron and steel scraps is increasing as well. Scrap recycling, however, is subject to some problems, such as unstable supply conditions, contamination by impurities, and so on. Given the huge volume and the wide variety of steel products being used in our society, information about the location, the volume, and the properties of steel materials is difficult to obtain. Owing to its huge volume, the stock of steel materials in our society plays 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 an efficient management of rare resources, it is of importance to obtain information about 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 the 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). The results indicate that importance of sorting scrap on the basis of the composition of alloying elements.