The inclusion evolutions after calcium treatment in Al-killed steel with different sulphur content were determined by chemical experiments and thermodynamics calculations. The results show that the inclusions are calcium aluminate with a little amount of calcium sulphide in low content sulphur steel after calcium treatment. As the sulphur content in steel increases, the typical inclusions generated in steel are layered or homogeneous irregular oxysulphides. A number of pure sulphides can be observed in higher content sulphur steel, and the morphology of sulphides with different CaS/MnS mass ratio has different shape. Thermodynamics calculations of Al-Ca-O-S-Mn system inclusions in steel at 1873 K and during solidification process were comprehensively conducted, considering all types of inclusions. The experimental results are in good agreement with thermodynamic calculations, which can predict the formation of the inclusions in Al-killed steel with different sulphur content.

In this investigation, a pilot-scale fluidized magnetization roasting reactor was introduced and used to enhance magnetic properties of iron ore. Consequently, the effects of roasting temperature, reducing gas CO flow rate, and fluidizing gas N2 flow rate on the magnetization roasting performance were studied. The results indicated that the hematite was almost completely converted into magnetite by a gas mixture of 4 Nm3/h CO and 1 Nm3/h N2 at roasting temperature of 540?C for about 30 s. Under optimized conditions, a high grade concentrate containing 66.84% iron with iron recovery of 91.16% was achieved. The XRD, VSM, and optical microscopy (OM) analyses revealed that most of the hematite, except some coarse grains, was selectively converted to magnetite, and that the magnetic properties were greatly enhanced. Thus, their separation from non-magnetic gangue minerals was facilitated.

In current article, experiments with different calcium addition were carried out in an Al 2 O 3 crucible at 1873 K to investigate the variation of inclusion in Ti-bearing Al-kill Steel. It was found that calcium significantly influenced the morphology, composition distribution and size of oxide inclusions in Ti-bearing Al-kill Steel. Liquid oxide inclusions were modified promptly after calcium addition. Meanwhile, calcium could also modify solid titanium aluminate inclusions to spherical ones similarly, but there were a number of multilayer inclusions in molten steel at the initial stage. Different calcium treatment level should be adopted in different titanium content steel production process. As for the production practice, to achieve the full liquid inclusions in molten steel, the amount of calcium and titanium should be controlled simultaneously during the production process.

Based on the thermodynamic assessment of inclusions evolution, the modification experiments of inclusions containing rare earths were carried out in the Si-Mo furnace from 1600°C to 1500°C. The pure Si and Si-Al alloy were chosen as deoxidants under low and high initial oxygen content, respectively. The field emission scanning electron microscope (FE-SEM) and energy dispersive spectrometer (EDS) were employed to analyse the morphology and chemical compositions of inclusions in the samples. The spherical liquid Ce-Si-Al-O (Ce 4 Si 5 Al 5 O 23.5 ) inclusions were observed in the steel, which was deoxidised by Si-Al alloy. The evolution mechanisms of inclusions were comprehensively discussed, and models for the formation of oxide inclusions were set up.