Sinter return is an undersized material, typically less than 5 mm, that is screened out either from the sintering machine after the cooler or just before being loaded into blast furnaces. It is generally recirculated back to the sintering machine and forms a significant portion of sinter blends. As it has undergone the sintering reactions and shows a considerably lower melting temperature compared with the natural ores in the sinter mixture, sinter return is believed to promote formation of sinter melt, the precursor of sinter bonding phase. As such use of sinter return during sintering has rarely been questioned despite its being a revert material from the process. However, with the global response to the threat of climate change, sinter plants are under increasing pressure to improve their efficiency and reduce their carbon footprint from both environmental and economic perspectives. Hence, it becomes increasingly important to re-visit and understand the role of the sinter return in the sinter mixture to optimise sintering performance and support future steel industry decarbonisation.