Toward an efficient recycling system: Evaluating recyclability of end‐of‐life stainless steels by considering elements distribution during a remelting process

Abstract

AbstractStainless steel is a special category of steel and contains high chromium and nickel. With particular attention to chromium and nickel, the solvent metal phase of recycling of end‐of‐life (EoL) ferritic and austenitic stainless steels by remelting is considered Fe–Cr alloy and Fe–Cr–Ni alloy instead of pure iron, respectively. Understanding the element elimination behavior from the solvent metal phase during the remelting process is important for the improvement of the resource efficiency of the stainless steel recycling. The elimination behavior of 23 alloying elements from Fe–Cr alloy and 22 alloying elements from Fe–Cr–Ni alloy were quantitatively evaluated by the thermodynamic method. The conventional metallurgical process, including slagging (oxidation) and evaporation, can efficiently eliminate lots of alloying elements but has its limitation for the elimination of some alloying elements such as copper, antimony, and tin. Moreover, improvement of the elimination is hard to expect with optimizing remelting conditions. Developing novel metallurgical refining processes, such as chlorination and sulfurization, is efficient for eliminating specific alloying elements. However, besides the effort from metallurgical technologies, developing advanced physical separation technologies of collected EoL products in the short term and optimizing the alloy/products design principle in the long term are much more important for improving the resource efficiency of recycling of EoL stainless steel products. Feedback of the alloying elements' elimination behavior during the remelting process to the upstream of the stainless steel cycle is critical.