A review of thermochemical processes and technologies to use steelworks off-gases

The steel industry is the main generator of CO2 among the different industrial sectors. That is why efforts are being made to reduce or avoid CO2 emissions by process optimisation or by Carbon Capture and Storage (CCS) processes. In the steel production by blast furnace technology, three main off-gases are generated, namely the Blast Furnace Gas (BFG), the Coke-Oven Gas (COG) and the Basic Oxygen Furnace Gas (BOFG). Many processes and technologies can be identified for their use, depending on the volume and composition of the steelwork off-gases. In the present work, a review and an analysis of several alternatives proposed during last years to use these off-gases are carried out, with a particular focus on thermochemical processes. Three main alternatives are considered: the thermal use of the gases, the recovery of valuable compounds for selling and the synthesis of a high-added value product. The possible implementation of these alternatives may conduct to improvements in energy efficiency of the steel making process with subsequent reduction of CO2 emissions.