Heavy melting steel

Heavy melting steel (HMS) or heavy melting scrap is a designation for recyclable steel and wrought iron. It is broken up into two major categories: HMS 1 and HMS 2, where HMS 1 does not contain galvanized and blackened steel, whereas HMS 2 does. The Institute of Scrap Recycling Industries breaks up the categories further:
HMS 1 and 2 are widely traded, particularly in the western hemisphere.
Both HMS 1 and 2 comprise obsolete scrap only - iron and steel recovered from items demolished or dismantled at the end of their life.
Because both grades guarantee a minimum piece thickness – at least for HMS 1, and for HMS 2 – consignments have a high density. Both also have defined maximum dimensions (usually ), and should be prepared to facilitate handling and charging to a furnace.
This density, sizing and preparation makes for efficient furnace operation by minimising the time to charge enough scrap for a full melt. In contrast, thin mixed scrap greatly increases charging time, cutting furnace productivity.
Variations on maximum piece size are covered by ISRI (North America’s Institute of Scrap Recycling Industries) codes. HMS is usually traded as a blend of 1 and 2, either a premium blend (80:20) or lower grade mixes (70:30) and (60:40). Other major heavy scrap grades include Japan’s H2 and A3 from the CIS.