Cast-iron cookware
Because other cookware cleaning techniques like scouring or washing in a dishwasher can remove or damage the seasoning on a bare cast-iron pan, these pans should not be cleaned like most other cookware. Some chefs advocate never cleaning cast-iron pans at all; simply wiping them out after use, or washing them with hot water and a stiff brush. Others advocate washing with mild soap and water, and then re-applying a thin layer of fat or oil. A third approach is to scrub with coarse salt and a paper towel or clean rag.
Scrap
A scrap metal shredder is often used to recycle items containing a variety of other materials in combination with steel. Examples are automobiles and white goods such as refrigerators, stoves, clothes washers etc. These items are labor-intensive to manually sort things like plastic, copper, aluminum and brass. By shredding into relatively small pieces, the steel can easily be separated out magnetically. The non-ferrous waste stream requires other techniques to sort.