Corex process

This process called KR process too is the most advance smelting reduction process a 1000t/d plant in operation in South Africa since 1988.This process was developed by Deutsch Voest-Aline in Austria.Corex process consists of two reactors, the reduction shaft and the melter-gasifier. The reduction shaft is placed above the melter-gasifier and reduced iron bearing material descends by gravity. The volume of the reduction shaft and the melter-gasifier is about 600 m³ and 2200 m³ respectively(fig1):

Melter –gasifier: Coal is fed into the gasfieder where it comes into contact with a reducing gas at a temperature of ca.1000-1100 ^oC .Reducing gas is produced via burning coal particles with oxidation in fluidized bed. At first carbon is oxidized to carbon dioxide, then carbon dioxide reacts with free carbon according the Boudouard reaction to form carbon monoxide:

C + O₂ = CO₂

CO₂ + C = CO

The gas temperature in the fluidized bed is in the range of 1600 – 1700 ^oC,during this process iron ore are melted and produced pig iron and slag .On the tope of gasifier a reducing gas is produced with following analysis:

65 – 70% CO

20 -25 % H₂

2-4% CO₂

The remaining constituents are metane,N₂ and steam. After leaving the melter –gasifier ,the hot gas is mixed with cooling gas to obtain a temperature of ca 850 -900 ^oC.

Shaft furnace: At a temperature of 850-900 ^oC the prereduction of iron ore is occurred in the shaft furnace. The continuous transfer of the hot material from the prereduction furnace to the melter gasifioe is occurred by a special controllable transport system. The metallization of the product is 90-95% and carbon content ca.3-5 %.