2014 年 100 巻 6 号 p. 740-749
In recent years, while comparing materials has been actively performed by utilizing LCA, in consideration of the lifecycle of a material, recycling is an important factor that influences the overall lifecycle of the materials. However, there is little material of which statistical data in the recycling industry, in other words the venous industry, is arranged. In addition, a definition of the recycling and an amount of material being recycled are different for each material and further, even though it is the same material, the definition of the recycling and the amount of material being recycled are greatly different depending on publicized reports.
Among the materials, qualitatively, steel material is said to have high recycling performance but there is not much statistical data regarding recycling thereof. Thus, it is often to indicate a quantitative recycling rate as Recycled Content (a ratio of using steel scrap). However, the Recycled Content of steel manufacturing in Japan is as low as 30%, in accordance with a recent increase in steel consumption, which gives an impression departing from the original meaning of qualitatively “high recycling performance”.
Based on the above background, we have collected the quantitative data regarding steel manufacturing for each country of the world and estimated world steel stock (accumulated) in 2008 using the collected data in consideration of a loss or the like in the steel making process. As a result of the estimation, the world steel stock (accumulated) in 2008 was 22 billion tons including the amount of loss. This amount was converted into an amount in terms of Fe and it was estimated that there was 20.8 billion tons excluding the amount of loss. In this review, the recycling rate is considered to be an obsolete scrap recovery ratio and the idea and the estimation method are presented. As a result of collecting data for a long period of time, verifying data and examining the inspection method, material balance of the steel is confirmed and a world steel recycling circuit can be created.
