Top Gas Recycling
The concept of the Top Gas Recycling Blast Furnace relies on separation of the off gases so that the useful components can be recycled back into the furnace and used as a reducing agent. This would reduce the amount of coke needed in the furnace. In addition, the concept of injecting Oxygen(O2) into the furnace instead of preheated air, removes unwanted Nitrogen(N2) from the gas, facilitating Carbon dioxide(CO2) Capture and Storage (CCS).
To experimentally test this concept a gas separation plant was constructed next to LKAB's Experimental Blast Furnace in Luleå, Sweden. On the experimental blast furnace, facilities were installed to operate with pure Oxygen(O2) and with re-injection of Carbon monoxide(CO) gas. The combination of the modified blast furnace and the gas separation plant was successfully tested in 2007.
Plans are currently being developed to test this principle on a commercial scale blast furnace. This will take place in the next phase of the ULCOS project, ULCOS II requiring an initial R&D investment of several hundred million Euros.