Direct-reduced iron (DRI), also called sponge iron, is produced from direct reduction of iron ore (in the form of lumps, pellets or fines) by a reducing gas produced from natural gas or coal. The reducing gas is a mixture majority of hydrogen (H 2 ) and carbon monoxide (CO) which acts as reducing agent. This process of directly reducing the iron ore in solid form by reducing gases is called direct reduction . Alternative iron source produced by heating an iron ore (generally having 65 to 70 percent iron) at a temperature high enough to burn off its carbon and oxygen content (a process called reduction ) but below iron's melting point(1535°C or 2795°F). The output is sold as pellets or briquettes (called hot briquetted iron or HBI) and contains from 90 to 97 percent pure iron, the rest being mainly carbon with trace amounts...