Surface Technology (表面技术)•2026•DOI: 10.16490/j.cnki.issn.1001-3660.2026.09.003
Additively manufactured (AM) titanium alloys are increasingly deployed in aerospace, medical, and high-end equipment sectors owing to their high design freedom, material utilization efficiency, and superior mechanical properties. However, insufficient surface quality and dimensional accuracy necessitate post-processing. This study investigates the performance of two-dimensional ultrasonic vibration-assisted turning (2D UVAT) on AM titanium alloys under dry and wet cutting environments, comparing it against conventional turning (CT). Cutting forces were measured using a Kistler 9257B dynamometer; surface morphology and roughness were characterized with a Super Viewer surface profiler; surface hardness was assessed via a TMVS-1 digital micro-Vickers hardness tester; and tool adhesion was analyzed through scanning electron microscopy and EDX composition mapping. Results demonstrate that under dry cutting conditions, 2D UVAT reduces the main cutting force by up to 25.50% at a feed rate of 0.05 mm/r compared to CT. Under wet cutting conditions, the maximum reduction in main cutting force is 22.73%. Surface roughness decreases by 21.28%–37.11% in dry cutting and 14.68%–38.63% in wet cutting. The average surface hardness of 2D UVAT specimens consistently exceeds that of CT specimens. Furthermore, tool rake face adhesion is markedly reduced in 2D UVAT, attributed to lower friction and cutting forces that mitigate adhesive wear. These findings confirm that 2D UVAT substantially improves machined surface integrity and tool performance when turning AM titanium alloys, offering a viable strategy for enhancing post-processing quality in high-value AM components.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-025-3121-y
This study explores a hydrogen-assisted mineral phase transformation process with synergistic desulfurization for the efficient recovery of iron from the high-pressure acid leach (HPAL) tailings of laterite nickel ore. HPAL tailings containing 51.50wt% iron and 2.09wt% sulfur present environmental challenges due to their sulfur content. Pre-treatment at 950°C for 15 min successfully reduced the sulfur content to 0.295wt% and increased the iron grade to 57.66wt%. Further hydrogen-assisted mineral phase transformation at 520°C for 30 min, using 40vol% hydrogen and a gas flow rate of 600 mL·min–1, resulted in a product with an iron grade of 61.00wt% and 90.11% iron recovery. The overall desulfurization rate reached 85.83% when wet scrubbing and limestone were used to capture the sulfur. This study demonstrates the efficiency of this hydrogen-assisted process for sustainable iron recovery and sulfur removal from laterite nickel ore tailings, with potential for industrial applications.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-024-3018-1
As a refractory iron ore, the clean and efficient beneficiation of limonite is crucial for ensuring a sustainable long-term supply of iron metal. In this study, the microwave fluidization magnetization roasting of limonite was explored. The micromorphology, microstructure, and mineral phase transformation of the roasted products were analyzed using a scanning electron microscope, an automatic surface area and porosity analyzer, an X-ray diffractometer, and a vibrating sample magnetometer. Kinetic analysis was also conducted to identify the factors limiting the roasting reaction rate. Microwave fluidization roasting significantly increased the specific surface area of limonite, increased the opportunity of contact between CO and limonite, and accelerated the transformation from FeO(OH) to α-Fe2O3 and then to Fe3O4. In addition, the water in the limonite ore and the newly formed magnetite exhibited a strong microwave absorption capacity, which has a certain activation effect on the reduction roasting of limonite. The saturation magnetization and maximum specific magnetization coefficient increased to 23.08 A·m2·kg−1 and 2.50 × 10−4 m3·kg−1, respectively. The subsequent magnetic separation of the reconstructed limonite yielded an iron concentrate with an Fe grade of 59.26wt% and a recovery of 90.07wt%. Kinetic analysis revealed that the reaction mechanism function model was consistent with the diffusion model (G(α) = α2), with the mechanism function described as k = 0.08208exp[−20.3441/(RgT)]. Therefore, microwave fluidization roasting shows significant potential in the beneficiation of limonite, offering a promising approach for the exploitation of refractory iron ores.
Int. Journal of Minerals, Metallurgy and Materials (矿物冶金与材料学报)•2025•DOI: 10.1007/s12613-024-3053-y
Hydrogen-based mineral phase transformation (HMPT) technology has demonstrated its effectiveness in separating iron and enriching rare earths from Bayan Obo refractory ores. However, further research is needed to clarify the phase composition and floatability of rare earths obtained after HMPT owing to the associated phase transformations. This study explored the mineralogical characteristics and separation behavior of rare earths in HMPT-treated iron tailings. Process mineralogy studies conducted via BGRIMM process mineralogy analysis and X-ray diffraction revealed that the main valuable minerals in the tailings included rare-earth oxides (9.15wt%), monazite (5.31wt%), and fluorite (23.52wt%). The study also examined the impact of mineral liberation and gangue mineral intergrowth on flotation performance. Flotation tests achieved a rare-earth oxide (REO) grade of 74.12wt% with a recovery of 34.17% in open-circuit flotation, whereas closed-circuit flotation resulted in a REO grade of 60.27wt% with a recovery of 73%. Transmission electron microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy revealed that monazite remained stable during the HMPT process, while bastnaesite was transformed into Ce7O12 and CeF3, leading to increased collector consumption. Nonetheless, the HMPT process did not significantly affect the flotation performance of rare earths. The enrichment of fluorite in the tailings highlighted its further recovery potential. The integration of HMPT with magnetic separation and flotation presents an efficient strategy for recovering rare earths, iron, and fluorite from Bayan Obo ores.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2024•DOI: 10.1016/j.ijmst.2024.12.006
The storage of solid waste in Bayan Obo has resulted in significant resource wastage and environmental concerns. In this study, an efficient process was developed to recover iron and rare earth elements (REEs) from this waste by processes of hydrogen-based mineral phase transformation (HMPT), magnetic separation, and flotation. Under optimal HMPT conditions (525 °C, 12.5 min, and 30% H2 concentration), an iron concentrate with a TFe grade of 64.09% and a recovery of 95.33% was obtained. The magnetic properties of the solid waste were greatly enhanced by HMPT, allowing the effective magnetic separation of iron minerals. Further optimization of the flotation process resulted in a REEs concentrate with a rare earth oxide (REO) grade of 65%–70% and a REEs recovery of 60%–65%. Hematite was reduced to magnetite during HMPT, and bastnaesite was decomposed to REEs oxides and fluorides, and the particle structure was significantly destroyed. However, changes in monazite, fluorite, and barite were minimal.