Dr Tuyen Nguyen

The increase of hydrogen usage in a blast furnace is expected to affect the reduction degradation of ferrous burden materials and influence the gas permeability inside the furnace. Previous studies show a disagreement on the effect of H2 on reduction degradation, with the extent of degradation depending on the H2 content and type of ferrous burden materials. In this study, the reduction degradation of sinter, lump, and pellet was compared using the reduction degradation test under different gas mixtures containing CO and H2, covering the gas composition of conventional and H2 injection blast furnaces. Lump (Newman Blend Lump NBLL) and pellets show a lower RDI-2.8 than sinter under all the gas compositions tested. Higher RDI-2.8 values were obtained for all burden materials with a reducing gas containing both CO and H2 compared to CO or H2 only. The addition of H2 to CO increases the pore diffusion rate allowing reducing gas to reach the centre part of the particles, leading to the reduction of hematite to magnetite and subsequent crack formation across the whole particles. Compared to the conventional blast furnace case, NBLL lump and sinter show a lower degradation for the H2 injection case while it was the opposite for the pellet, suggesting the necessity of reviewing overall burden materials to optimise the hydrogen injection in the blast furnace.

This study examined the strength of sinter analogue tablets for different types of iron ore under varying sintering conditions. A steel tamper was designed to quantify strength based on the percentage of 1 mm retained size after a drop weight test. The study found a linear relationship between total melt fraction M and strength index S quantified by mass fraction of the +1 mm retained size: S=0.88M. Importantly, a relationship was found between the total melt and a combined F factor incorporating the thermodynamic liquid fraction (a, representing sintering conditions) and the mineralogical factor loss on ignition (LOI ratio, ß, representing ore types), where F=6.5a+ß-1. This factor F was found well correlated the total melt via an asymptotic exponential relationship as M=1-2.6e-F. The results also suggested that, to achieve an acceptable strength of 80% +1 mm for a typical basicity B = 2, a sintering temperature range between 1273 and 1370 °C is required for the LOI range between 1.6% to 10.7% respectively. Finally, an analogous analysis was also carried out which proposed a similar trend between sinter yield obtained in a kilogram-scale by lab-scale studies and the present 0.6-g analogue scale.

Oil spills pose significant threats to marine and freshwater environments, impacting ecosystems and drinking water sources. The present review incorporated an up-to-date statistical analysis of the oil spills globally including the types and sources of oil spills and the main habitats affected by the past incidents. It presented immediate and long-term effects on aquatic organisms and habitats highlighting the necessity for action to protect the aquatic environment. The paper also elucidated a range of effective remediation and cleanup methods, presenting a comprehensive toolkit to mitigate ecological damage. Noticeably, the review identified crucial knowledge gaps in the literature: (i) the absence of marine plastic pollution in studies on oil spill impacts and (ii) the absence of a modeling framework that considers the presence of microplastics in the spillage region and their impacts on the overall weathering rate. From synthesizing essential knowledge on oil spill dynamics and identifying the knowledge gap in the literature, this review aims to enhance understanding and guide future research.

Slags are a co-product produced by the steel manufacturing industry and have mainly been utilised for aggregates in concreting and road construction. The increased utilisation of slag can increase economic growth and sustainability for future generations by creating a closed-loop system, circular economy within the metallurgical industries. Slags can be used as a soil amendment, and slag characteristics may reduce leachate potential of heavy metals, reduce greenhouse gas emissions, as well as contain essential nutrients required for agricultural use and environmental remediation. This review aims to examine various slag generation processes in steel plants, their physicochemical characteristics in relation to beneficial utilisation as a soil amendment, and environmental implications and risk assessment of their utilisation in agricultural soils. In relation to enhancing recycling of these resources, current and emerging techniques to separate iron and phosphorus slag compositions are also outlined in this review. Although there are no known immediate direct threats posed by slag on human health, the associated risks include potential heavy metal contamination, leachate contamination, and bioaccumulation of heavy metals in plants, thereby reaching the food chain. Further research in this area is required to assess the long-term effects of slag in agricultural soils on animal and human health.

Analogue sinter tablets were produced at temperatures between 1250°C and 1320°C, with a range of hold times and cooling rates. Platy silico-ferrite of calcium and aluminum (SFCA) morphology was identified in samples produced at 1250°C using reflected light microscopy; however, quantitative x-ray diffraction (XRD) identified the presence of the SFCA phase, with no SFCA-I detected. This proves that the platy SFCA morphology common in analysis by reflected light microscopy cannot be attributed to the SFCA-I mineral without further analysis. Micro-XRD and electron probe micro-analysis (EPMA) were carried out on an area of platy SFCA confirming this result. The sinter analogue tablets were reduced in a 30% CO, 70% N2 gas mixture at 900°C in a tube furnace thermo-gravimetric analyzer. The degree of reduction of the tablets in this study was found to be controlled by the porosity of the samples, rather than by the morphology or mineralogy of the bonding phase.

Vaporization of atomized feedstock is one of the critical processes in fluid catalytic cracking (FCC) risers; which is more often ignored in most of the FCC riser modelling studies. In this study, two different vaporization mechanisms of feedstock namely homogeneous mode and heterogeneous mode were studied. Different homogeneous models duly validated for various pure component droplets were applied to predict the vaporization time of the feed droplets typically expected in FCC feed vaporization zone. A new physical model for heterogeneous vaporization considering droplet-particle collision mechanics was also developed in the present study which compared well with the other existing heterogeneous modelling approaches. Comparison of the two vaporization modes indicates that under typical operating conditions of FCC riser, vaporization time of feed droplets predicted by heterogeneous mode is always lower than the homogeneous mode at least by an order of magnitude due to significant increase in heat transfer coefficient which accounts for droplet-particle contact. It is expected that actual vaporization time of feed droplets in an industrial FCC riser should lie in the range predicted by these two vaporization mechanisms which actually set the two limiting modes of vaporization. Obtained results predicted by the models could be used to aid design of the FCC feed vaporization zone.