One feature of steel materials is their recyclability. Steel used in civil engineering, construction, shipbuilding, automobiles, home electrical appliances, containers, etc. is recovered as steel scrap. In any country, increasing per capita stock of steel ( ca.10　ton/head) usually increase the generation and recycling of waste steel scrap, although the local availability of hot metal and electricity causes some differences. A general trend during the past decades is that scrap-based steelmaking has increased its share, reaching around 49% of global crude steel production in 1994. The recycling of iron and steel scrap to steel melting shops is schematically described in the figure. In 1993, 456 million tons of scrap was generated worldwide, comprising obsolete scrap (272million tons), home scrap (88million tons), and prompt industrial scrap (96million tons). However, with the development of steel materials for higher grades and higher performance, use of steel materials in combination with nonferrous metals or nonmetallic materials has increased. It is estimated that non-volatile residuals (tramp elements) such as Cu, Sn, As, Sb, and Bi, especially Cu and Sn included in obsolete scrap will accumulate in the recycling of scrap by about 30% in 20 years if the present situation continues. The use of coated steels has increased during the last decade, mainly due to the galvanizing of sheets for the auto industry. In 1994, the amount of metal-coated steels produced within the European Union and Japan was, respectively, 19.5 and 16.0 million tons of which tin plate corresponded to 4.0 and 2.0 million tons, electro-chromium coated steels 0.7 and 2.0 million tons, and other metal coated steels 14.8 and 12.0 million tons, mainly galvanized. Organic materials in the coating generate harmful dioxines, and volatile residuals such as Zn and Pb cause metal and/or metal oxide fumes which are hazardous. In recycling, home scrap and prompt industrial scrap do not present major problems since their chemistry is well known and quality acceptable. The problem is obsolete scrap, which is estimated to account for about 2.7% (37million tons) of the accumulated total stock of steel (1,300million tons) in the year 2000 in Japan. This means that the percentage of obsolete scrap to total annual production of crude steel (e.g. 100million tons) becomes a high 37%. Recycling of steel scrap considerably contributes to the reduction of energy consumption and CO2 evolution as discussed in the next section which follows, except for the residuals constraint. For residuals, there seems to be only a few commercial means of mechanically removing mixed residuals by an enhanced shredding process or coated residuals by electrolytic leaching or vacuum heating. Virtually no economically feasible means have been developed as yet to remove the residuals alloyed in steel. Numerous trials have been made, but the methods tested have been inadequate to overcome the cost barrier. The current status of the processes for residuals removal is technically in progress, but not competitive at the commercial level. Many problems remain unresolved for promoting further recycling of iron resources to maintain the quality of steel products in the future while preventing quality fluctuation of the steel scrap. It is expected that these problems will be resolved with future steelmaking processes.