Concentrators are used in gravity-based separation and beneficiation processes to recover valuable minerals from slurry streams by differences in specific gravity and particle size. Common in mining and mineral processing operations, concentrators such as spiral units are often applied in coal, mineral sands, iron ore, chrome, and other heavy mineral circuits where reliable separation and low operating cost are important. Machinery & Equipment Co. currently shows this category with a Krebs spiral concentrator listing, and recognized names in the broader concentrator market include Krebs, Multotec, Mineral Technologies, and Humphreys-style spiral systems.