Considerable efforts have been made in the academia, industry and R&D to investigate metallurgical processes in blast furnace main trough (BFT) and trough performances. In these, while the emphasis in industrial research has been primarily on the mechanism of BFT refractory degradation as well as the development of high-performance refractory formulations, noteworthy efforts in the academia have been parallelly made to study air-hot metal-slag flows, jetting and splashing behaviour, slag-metal separation, flow stresses on refractory walls, temperature distribution, and so on. CFD (computational fluid dynamics), physical modelling and high-temperature field trials have all been extensively applied to investigate diverse phenomena in blast furnace trough. In the present work, four decades of research and a large number of archival publications on blast furnace trough (BFT) have been reviewed and analysed primarily to document the state of the art and identify knowledge-gaps that continue to exist. In such context, many studies reveal that oxidation of refractory lining along metal-line and chemical reaction together with mass transfer along the slag-line are primarily responsible for trough refractory degradation wherein, multi-phase flows of air-hot metal and slag, particularly in the jet entry region, play important roles. CFD studies coupled with industrial-scale measurements have conclusively demonstrated that wear, erosion, dissolution, etc. of trough refractory are the combined result of fluid flow as well as heat and mass transfer phenomena and therefore, characterisation of refractory degradation solely in terms of mechanical or flow stresses is not justified. Many modelling and experimental studies have further indicated that while refractory formulation and layout determine thermal fields within trough refractory lining and influence latter’s service life, physical dimensions and design of the main trough, on the other hand, tend to exert considerable influence on metal loss and slag entrainment phenomena. Plant scale trials have shown that blast furnace operating parameters, most importantly, throughput rate and hot metal temperature exert considerable influence on BFT refractory performance. As a consequence, trough refractory formulation and design have undergone many changes over the years resulting in the development of Al2O3–SiC–C based castables and thereby, fulfilling many requirements of the modern-day blast furnace ironmaking practices. In addition to such, the present review has indicated that sustained R&D efforts in industry helped produce BFT castables with controlled porosity and particle size distribution leading to considerable performance enhancement and specific refractory consumption, as low as 0.35 kg per tonne of hot metal. The review has brought out that collaborative research, between industry and academia, has been fruitful towards many developments presented in the review.
