"scrap steel in municipal solid waste" refers to discarded steel products generated during residents' daily lives and social consumption, such as obsolete household appliances, furniture, cookware, and packaging containers. These materials lose their original functionality or, although not completely devoid of utility, are discarded and mixed into municipal solid waste. After processing via waste sorting, magnetic separation, shredding, and impurity removal, this type of scrap steel can be recycled as an iron resource and reused in metallurgical processes for steelmaking or as recycled raw material in industries such as construction materials and machinery manufacturing.