The utilization status and problems of solid waste in iron and steel industry

Iron and steel industry is a typical resource-intensive industry. Steel production of rectangular hollow section needs to consume a large amount of iron ore, coal, new water and other resources and produce a large number of “three wastes” resources. According to statistics, for each ton of crude steel produced by long-process steel enterprises, about 0.7 tons ~ 0.8 tons of coal, 1.5 tons ~ 1.55 tons of iron ore, as well as a large amount of raw materials such as limestone flux, the solid waste production of tons of steel is about 600 kg. According to the different interface, the solid wastes mainly include blast furnace slag, steel slag and environmental dust. According to preliminary estimates, the iron and steel industry produces 500 million tons of solid waste every year.

Since the 13th five-year plan, with the increase of pig iron and crude steel output, bulk industrial solid waste such as furnace slag and steel slag has also been on the rise. It is estimated that China’s blast furnace slag increased from 251 million tons in 2015 to 270 million tons in 2018, with an average annual growth rate of 3.7%. Mild steel tube grew from 104 million tons in 2015 to 114 million tons in 2018, with an average annual growth rate of 4.7%.

At present, the production and utilization of solid waste in China’s iron and steel industry mainly show the following characteristics: First, solid waste production.The production of solid waste in China’s iron and steel industry accounts for about 15% of the country’s industrial solid waste. At the same time, China’s steel production is mainly based on the long-process of blast furnace and converter. By the end of 2018, China’s long-process production of hot rolled square steel tube accounts for nearly 90% and the solid waste production of tons of steel is higher than that of the short-process technology of electric furnace. Second, solid waste species, complex components. Due to the influence of steel production process and steel type, the composition of ferruginous sludge produced by different processes is different, and the steel composition of different steel types is quite different. Third, standardized disposal and resource utilization pressure. There are many steel pipe suppliers with low concentration, so it is difficult for a single enterprise to make large-scale economic use of some small amount of solid waste. In addition, the utilization of solid waste in China’s iron and steel industry still has the problems of small enterprise scale. In particular, the research and development of solid waste utilization technology, promotion and industrialization of equipment are insufficient, which has become an important factor restricting the standardization and scale development of solid waste utilization industry.