Dios Process

The Dios process is a bath smelting process, intensively investigated in Japan. Iron oxide is preheated in the first of two fluidized bed reactors in series and pre-reduced to 15-25% in the second reactor using cleaned off-gas from the smelter. In addition, a small amount of coal fines is injected into the smelter off-gas to cool the off-gas and provide additional CO and H2 for pre-reduction. Coal is gravity fed into the smelter. Oxygen is injected into the smelter for combustion of coal and for post combustion.

Development Status Products

Dios ProcessCosts & Benefits

Parent Process: Smelting Reduction
Energy Savings Potential

Net energy consumption decreases by 3 to 4%. Low direct electrical power consumption. Coal Consumption in Dios process is 950 kg/tHM.

CO2 Emission Reduction Potential

CO2 emissions in the Ironmaking process decreased by 4 to 5%.


Investment costs for the technology are 65% of that of BF investment cost.

Dios Process Publications