The composition of TBFS is complex. It is categorized into low (W_(TiO2) < 5%), medium (5% < W_(TiO2) < 20%), and high-titanium slag (W_(TiO2) > 20%) based on Ti content. The titanium in the slag is underutilized, causing it to accumulate and contribute to environmental pollution. Current methods for extracting titanium from TBFS include acid leaching, alkali fusion roasting, high-temperature carbonation–low-temperature chlorination, electrochemical molten salt electrolysis, and selective enrichment. However, these methods still face challenges such as environmental impact, high costs, low Ti recovery, and low Ti grade. This paper summarizes the mechanisms and characteristics of the above methods. Future research should focus on integrating pyrometallurgy with beneficiation processes, followed by further purification of titanium-rich phases through hydrometallurgy. Additionally, combining this with novel separation technologies (such as microwave and superconducting magnetic separation) will optimize the dissociation of titanium-bearing phases after enrichment.

Extracting vanadium (V) from vanadium slag (VS) by the traditional roasting-leaching process has disadvantages of high energy consumption and high poisonous gases emission. In this work, a green and efficient route was developed to extract V from VS without roasting by electro-oxidation combined with ultrasound cavitation (EOUC) intensification in sulfuric acid solution. The leaching parameters (e.g., leaching temperature, sulfuric acid concentration, anodic current density, ultrasound power, liquid to solid ratio, leaching time and particle size) were optimized. The leaching mechanism was explored by comparing the leaching behavior and mineralogical evolution of the direct sulfuric acidic leaching (DSL), electro-oxidation-assisted sulfuric acidic leaching (EOSL), ultrasound cavitation-assisted sulfuric acidic leaching (UCSL) and EOUC methods. The results show that introducing electric field strengthens the ultrasound cavitation effect on slag particles in sulfuric acid solution. Under the optimum parameter of EOUC method, the leaching rate of V from VS is as high as 94.64 %. Using EOUC method can open the silicate-wrapped structure of the spinel, increase pore volume of VS from 0.00127 cm³ g^-1 to 0.01124 cm³ g^-1, decrease slag particle size from 26.8 μm to 16.4 μm and improve specific surface area from 0.508 m² g^-1 to 10.855 m² g^-1, which significantly accelerate V leaching process. The exposed spinel was oxidized by both electrochemical route and chemical route, forming a mixture of V³⁺ ion and VO²⁺ ion after leaching.

Multi-source ferrous metallurgical dust and sludge are significant components of iron-containing solid waste in the iron and steel industry. It is crucial for the sustainable operation of steel enterprises to recycle iron from ferrous metallurgical dust and sludge (FMDS) for use in steel smelting. However, besides Fe, FMDS also contains valuable elements such as Zn, Pb, K, and Na, among others. While these valuable elements hold high recovery value, they impede the direct reuse of FMDS by iron and steel enterprises. This paper introduces the compositional characteristics of multi-source ferrous metallurgical dust and sludge, analyzes the main recycling technologies associated with FMDS at the present stage of development, and discusses the characteristics of different technologies. In view of this, a new idea of the “cooperative treatment of multi-source ferrous metallurgical dust and sludge—full quantitative recovery of valuable elements” is put forward. This new idea integrates a variety of treatment processes to directly recycle FMDS within the steel plant, enhancing the adequacy of dust and sludge recovery and reducing the risk of environmental pollution. This paper provides a reference for achieving the full quantification and utilization of high-value-added FMDS in steel plants.

Steel metallurgical dust, characterized by a substantial output, minute particle size, and intricate composition, poses a considerable risk of environmental contamination while simultaneously embodying an exceptionally high potential for recycling. To achieve its resource utilization, chemical analysis, particle size analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy, and water leaching methods were employed to investigate the chemical compositions, particle size distributions, phase compositions, and microscopic morphologies of blast furnace bag dust, sintering dust, converter fine dust, and electric arc furnace dust from steel plants. The results indicate that the four types of dust have extremely fine particle sizes, with the main distribution range of particle size being less than 100 μm. The main constituent element is Fe (19–56%), and it also contains Zn (1.4–33.5%), Pb, K, C, and other valuable elements. Alkali metals in blast furnace bag dust and sintering machine head dust existed mainly in the form of chloride. The zinc phases in sintering machine head dust and converter fine dust were ZnFe₂O₄, and the zinc phases in blast furnace bag dust were ZnCl₂ and ZnFe₂O₄. Zinc in electric furnace dust was composed of ZnO and ZnFe₂O₄, accounting for 70.31% and 23.12%, respectively. There are significant differences in the types and contents of valuable elements among various dusts, making it difficult to achieve full-scale recovery through a single process. In view of this, a process of “in-plant recycling of harmless dusts—collaborative treatment of harmful dusts” has been proposed. Based on the characteristics of metallurgical dusts, multiple processes are used for collaborative treatment (using hydrometallurgical and pyrometallurgical methods), which can not only directly recover iron resources from dusts within the plant, but also avoid the waste of valuable elements such as Zn, Pb, K, Na, etc. It is hoped that the above work can provide a reference for steel enterprises to achieve full-scale and high value-added treatment of metallurgical dusts.

Titanium-extracted tailing is a by-product generated during titanium-bearing blast furnace slag treatment process. The crystallization behavior of the titanium-extracted tailing during the cooling process is significant to its utilization for glass ceramics preparation. In this work, the CaO-SiO₂-Al₂O₃-MgO-TiO₂-FeO slag was used to explore the effect of CaO/SiO₂ ratios on titanium-extracted tailing crystallization. FactSage 8.2 calculation and mineralogical characterizations were conducted to investigate the phase and microstructure evolution during the slag cooling process. Single hot thermocouple technique (SHTT) was employed for in situ observation of the crystallization process of the slag during the cooling process. The obtained results indicated that the perovskite, melilite, spinel, diopside and anorthite phases would be crystallized during the cooling process when the CaO/SiO₂ ratios of the slag were 0.7–1.1. Increasing the CaO/SiO₂ ratio to 1.3 and 1.5 promoted the crystallization of olivine and merwinite phases, however, inhibited the crystallization of diopside and anorthite phases. The initial crystallization temperature and the liquid phase disappeared temperature of the slag enhanced with improving CaO/SiO₂ ratios. The initial crystallization temperature was controlled by perovskite phase precipitation when the CaO/SiO₂ ratios of slag reached 0.7–1.3. Whereas the initial crystallization temperature was controlled by the crystallization of spinel phase when the CaO/SiO₂ ratio of slag was 1.5. The incubation time for crystal nucleation reduced with increasing CaO/SiO₂ ratios that promoted slag crystallization. Moreover, increasing the CaO/SiO₂ ratio from 0.7 to 1.5 enhanced the critical cooling rate from 4 °C s⁻¹ to 11 °C s⁻¹.