8.2.2.1 Recycling of iron and steel
The theory and practice of cast iron production and steelmaking has been discussed in Sections 7.2.10.5, 7.2.10.6 and 8.1.4. There is considerable use of both cast iron scrap and steel scrap in the production of cast irons using cupola and electric melting and up to 100% steel scrap usage in electric arc and open hearth steelmaking processes, whereas up to 30% steel scrap may be used to lower the melt temperature and reduce materials’ costs in converter steelmaking processes. The main problems in using scrap in steel making are the residual copper and tin levels which must be kept low to avoid serious reduction in mechanical properties. Higher levels can be tolerated in cast irons. Thermo dynamically, Cu and Sn are relatively noble elements and continually build up in the steel.