remelting

Remelting is the process of melting a material that has previously solidified, with the aim of refining composition, removing impurities, homogenizing microstructures, and enabling recycling. It is widely used for metals, including aluminum, steel, copper, nickel-based alloys, and precious metals, and is also applied in glass recycling. In metals, remelting can produce ingots with more uniform composition and improved mechanical properties.

Industrial remelting uses furnaces and methods designed to control atmosphere, temperature, and solidification. Common metal-remelting methods include electric arc furnaces (EAF) and induction furnaces for general melting, vacuum induction melting (VIM) to reduce oxidation, and dedicated remelting routes such as vacuum arc remelting (VAR) and electro slag remelting (ESR), which refine alloys under controlled conditions to remove impurities and achieve high purity. Plasma arc remelting is another variant used for certain specialty alloys. Each method differs in energy source, atmosphere, and the extent of impurity removal.

Purposes of remelting include refining out non-metallic inclusions and dissolved gases, homogenizing composition, and controlling the solidification structure. It enables recycling of scrap by converting it into high-quality ingots or billets and is essential for producing ultra-clean steels and high-performance alloys. However, remelting is energy-intensive and costly, and some impurities or microstructural features may persist or re-form during subsequent processing.

Applications span multiple materials. In metals, remelting supports production of steel, nickel-base superalloys, aluminum alloys, copper alloys, and precious metals. In glass, remelting of cullet and post-consumer glass reduces raw material demand and energy consumption compared to primary melting, supporting sustainable recycling programs.