Steel slag in China: Treatment, recycling, and management.

Steel slag is the main waste product in the steelmaking process. Because of its chemical composition and technical properties, it can be reused as raw material in steel plants and can serve as a substitute for aggregates in civil engineering. In this paper, we reviewed steel slag treatment, recycling, and management in China. Although China's annual slag production reached more than 100 million tons, its utilization rate is only 29.5%. As of 2016, more than 300 million tons of steel slag have not been used effectively. Large steel slag emissions are causing environmental problems for China. China's steel slag utilization rate is low compared with that of industrial countries: the utilization rate is 98.4% in Japan, 87.0% in Europe, and 84.4% in the United States. Compared with other nations, China also has a gap in its usage of slag in road construction and agriculture. Although the Chinese government has been active in creating a legislative and institutional framework to realize effective steel slag treatment and recycling, these efforts are limited. Outdated treatment approaches is one of the reason for low utilization rate in China, most Chinese steel plants carry out the preliminary treatment (like family workshops) of steel slag, no one system can be used for all ferrous waste recovery, and 47% enterprises' steel slag stability after treatment do not meet requirements of follow-up product. Road construction issues caused by high costs and policy limited, legal restrictions and lack of standard on agricultural applications are other two reasons for low utilization rate of steel slag. New policies are needed to improve utilization rates. We propose the concept of gradual utilization to promote the effective utilization of steel slag.