Worldwide steel production is still mainly achieved from primary manufacturing by carbon-intensive processes in integrated steel mills, making this industry the first in terms of direct CO2 emissions. Both carbon capture and storage (CCS) and carbon capture and utilization (CCU) approaches are currently considered to offer a solution to the high carbon-footprint of primary steel production. Design of available or development of new gas separation-purification technologies are at the heart of these strategies, and often represent the largest share of the total project cost. This work presents the current state of development of the main technologies that have shown potential thus far at pilot or industrial scale for the treatment of gases within the steelmaking industry. An analysis of the opportunities and limitations of each technology is presented, related to their ability to separate existing gas streams into the two main carbon-bearing species, CO2 and CO. Recovery of H-2, available in important quantities, is also considered. Main results from previous and ongoing research are presented and analyzed to draw a picture of the current situation, and offer key points for future development.