The crossword solution for the term 'smelting input' is ORE, which is an acronym for 'Original Rock Element'. ORE is a naturally occurring mineral or aggregate of minerals from which a valuable constituent, such as a metal, can be extracted. Smelting is the process of extracting a metal from its ORE by heating it to a high temperature. Therefore, smelting input refers to the ORE that is used as the source material for the smelting process.