section_path: Production of metallic iron/Direct iron reduction
section_name: Direct iron reduction
paragraph_text: Direct iron reduction
  
  Owing to environmental concerns, alternative methods of processing iron have been developed. " Direct iron reduction " reduces iron ore to a ferrous lump called "sponge" iron or "direct" iron that is suitable for steelmaking. Two main reactions comprise the direct reduction process:
  
  Natural gas is partially oxidized (with heat and a catalyst):
  
  Iron ore is then treated with these gases in a furnace, producing solid sponge iron:
  
  Silica is removed by adding a limestone flux as described above.