How do steel foundries melt scrap to make steel castings?

Steel foundries primarily use coreless induction furnaces or electric-arc furnaces to melt scrap for the production of steel castings.1

Melting Processes

• Induction Furnaces: These function as tiltable, refractory-lined crucibles surrounded by water-cooled induction coils. Alternating current creates an electromagnetic field that induces eddy currents, generating heat directly within the metallic charge. This method provides excellent stirring for alloying but offers very limited refining capabilities.2
• Electric-Arc Furnaces (EAF): These furnaces melt scrap using high-power electric arcs generated between electrodes and the charge. The process involves charging the furnace with scrap, melting it under controlled power settings, and potentially performing refining steps—such as adjusting carbon levels or using a two-slag practice to remove impurities like sulfur—to achieve the desired steel chemistry.3

Foundries often utilize high-quality return scrap, such as gates and risers from previous operations. Because extensive refining is frequently unnecessary, many foundries employ an acid process with a high-silica slag, allowing for the use of more economical acid furnace linings.1