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The titanium industry can hardly bypass the titania-containing slags, and the slag physicochemical properties are essential in the metallurgical reactor design and process control. The TiO2-FeO based slags and TiO2-SiO2-CaO based slags are the main metallurgical slag systems in the titanium resource utilization processes. To elaborate the role of TiO2 in the physicochemical properties of titania-containing metallurgical slags, the physicochemical properties including titanium redox ratio, liquidus temperature, viscosity, electrical conductivity, density, surface tension, thermal conductivity, and sulfide capacity were critically reviewed. Moreover, the property prediction models were briefly introduced with regards to the limitations of the existing models. The properties prediction models are still required to evolve since not all properties of titania-containing slags can be well modelled. As the slag structure has an intimate relationship with slag properties, the structural details of the titania-containing slag were investigated by using a combination of spectroscopic technologies, but the knowledge of the slag structure was not fully ascertained. The potential research fields related to the physicochemical properties and structure of the titania-containing slags were also suggested.

The effect of pre-oxidation degree of Panzhihua ilmenite concentrate on the gaseous reduction by carbon monoxide was investigated. The raw ilmenite concentrates were pre-oxidized at 600, 700, 800, 900, and 1000 °C for 2 h, respectively. The phase change, FeO content, and morphology after the oxidation at various temperatures were characterized. The oxidation degree was calculated according to the change of FeO content. Thermogravimetry was performed on the oxidized ilmenite concentrate samples (oxidized at 600, 800, and 1000 °C) at 850, 900, and 950 °C, respectively. The results show that the pre-oxidation of ilmenite concentrate can accelerate the reduction process: the higher pre-oxidation degree, the faster reduction rate. The high pre-oxidation degree of ilmenite concentrate is beneficial to accelerate the subsequent reduction process in two ways. Three stages of the reduction process were divided via the first derivatives of reduction degree, and the reduction mechanism and apparent activation energy were discussed subsequently.

The effect of the Al2O3 content and basicity (the molar ratio of MgO to SiO2) on the viscosity of a SiO2–MgO–FeO–Al2O3–CaO slag was studied to fully understand the smelting process of the ferronickel alloy. Experimental results show that the slag is a mixture of liquid and solid phases at the experimental temperature. The viscosity decreased as the basicity increased and increased as the Al2O3 content increased. To determine the effect of the Al2O3 content and basicity on the structure of the molten slag, Raman spectroscopy was performed on the slag sample, which was quenched from the high temperature with water. The Raman spectra showed that the fractions of the polymerization structural units decreased significantly as the basicity of the slag increased, resulting in a decrease in the apparent viscosity. However, Al2O3 acts as a network former in the slag system, thereby making the slag structure further polymerized and increasing the viscosity.

A novel granulation process that involved the use of a rotary multi-nozzles cup atomizer and water cooling was proposed for ferroalloy manufacturing. The effects of rotating speed and nozzle diameter on the properties of FeSi75 alloy (containing 75 wt.% Si) granules were investigated. Results indicated that median granule diameter decreased as rotating speed increased, and initially increased and then decreased as nozzle diameter increased. The optimal conditions for the granulation of FeSi75 alloy were a rotating speed of 150 r/min and nozzle diameter of 10 or 12 mm. The phase composition, micromorphology, and elemental distribution of the FeSi75 alloy granules were also studied by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectrometry. In order to provide guidance for the layout and water depth of the tank, the solidification behavior of ferrosilicon alloy droplet was numerically studied. A simplified model was established to elucidate the traveling trajectory and heat transfer of alloy droplet in air and cooling water during the atomization process. The solidification time of droplet with different thicknesses of solidification layer increased with the increase in alloy droplet diameter.

The effect of magnesia on calcium ferrite (CaO·Fe2O3) reduction by CO was examined by isothermal thermogravimetry. Samples of calcium ferrite added with 0, 2, 4, and 8 wt.% magnesia (abbreviated as CF, CF2M, CF4M, and CF8M) were prepared. Phase composition was analyzed by X-ray diffraction, and the results indicated that CF2M and CF4M are reduced to lower reduction degree and with lower apparent activation energy than CF; and CF8M with more MgO·Fe2O3 is reduced to a lower degree and with more difficulty compared with CF. Reduction rate analysis revealed that CF, CF2M, CF4M, and CF8M reductions are all typical two-step reactions with the order of CF → CWF (CaO·FeO·Fe2O3) → Fe. The apparent reduction activation energies of CF, CF2M, CF4M, and CF8M are 46.89, 37.30, 17.30, and 29.20 kJ/mol, respectively. Sharp analysis depicted that CF2M, CF4M, and CF8M reductions are all described by 2D Avrami–Erofeev (A–E) equation (A2) in the whole process, while CF reduction is first expressed by A2 and then by 3D A–E equation (A3). Different from shrinking core model, a new kinetic model for powdery samples reduction was proposed to illustrate the relationship among reduction rates, reduction routes, and model functions.

The non-isothermal oxidation experiments of ilmenite concentrate were carried out at various heating rates under air atmosphere by thermogravimetry. The oxidation kinetic model function and kinetic parameters of apparent activation energy (Ea) were evaluated by Malek and Starink methods. The results show that under air atmosphere, the oxidation process of ilmenite concentrate is composed of three stages, and the chemical reaction (G(α) = 1−(1−α)2, where a is the conversion degree) plays an important role in the whole oxidation process. At the first stage (α = 0.05−0.30), the oxidation process is controlled gradually by secondary chemical reaction with increasing conversion degree. At the second stage (α = 0.30−0.50), the oxidation process is completely controlled by the secondary chemical reaction (G(α) = 1−(1−α)2). At the third stage (α = 0.50−0.95), the secondary chemical reaction weakens gradually with increasing conversion degree, and the oxidation process is controlled gradually by a variety of functions; the kinetic equations are G(α)= (1−α)−1 (β=10 K · min−1, where β is heating rate), G(α) = (1−α)−1/2 (β=15−20 K · min−1), and G(α) = (1−α)−2(β=25 K · min−1), respectively. For the whole oxidation process, the activation energies follow a parabolic law with increasing conversion degree, and the average activation energy is 160.56 kJ · mol−1.