2008 Volume 48 Issue 5 Pages 696-704
The present flows of steel scraps in Japan, China, South Korea and Taiwan are described, and a dynamic model that analyzes future scrap flows was developed. To estimate obsolete scrap recovery, a population balance model (PBM) was used for Japan, South Korea and Taiwan. The PBM dynamically estimated the amount of discarded steel by taking into account steel input into a society by end use and the lifetime distributions of each end use. For China, obsolete scrap recovery was estimated using a leaching model, which used the steel stock and the recovery ratio of obsolete scraps. Three different methods were applied to forecast future steel input for each country. The first method applied the assumption that steel demand in the future remains at the present level. The second method applied a logistic curve to estimate future steel stock. The third method applied regression equations to future steel input by end use. GDP and population were used as variables. Finally, the steel input forecasts produced by each method were substituted into the obsolete scrap recovery estimation model. The logistic curve method estimated that in 2030 obsolete scrap recovery would be 29 million tons in Japan, 83 million tons in China, 20 million tons in South Korea, and 3.7 million tons in Taiwan.