Transactions of Nonferrous Metals Society of China (中国有色金属学报)•2026•DOI: 10.1016/S1003-6326(26)67066-5
Oxidation roasting of bastnaesite was conducted to evaluate its impact on surface characteristics and flotation behavior. Experiments varied temperature, time, and O2 concentration. Increasing temperature promoted thermal decomposition, yielding Ce7O12, RE2O3, and REF3 as main phases. The Ce oxidation degree and REO grade of roasted products exceeded 85.00%. Roasting induced long, narrow, nearly parallel cracks within particles, increasing porosity and causing partial fragmentation. During flotation, dissolved rare earth ion concentration increased significantly, and surface hydrolysis formed rare earth hydroxyl compounds. Complete decomposition raised the required collector dosage to achieve recovery above 85.00%. This increase is attributed to enhanced particle wettability, altered collector adsorption, and deeper penetration into the porous structure. The findings provide a basis for optimizing flotation circuits treating roasted bastnaesite, particularly in iron-bearing rare earth deposits where pyrometallurgical pretreatment is employed.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-024-01601-3
Soft robots have partially or entirely provided versatile opportunities for issues or roles that cannot be addressed by conventional machine robots, although most studies are limited to designs, controls, or physical/mechanical motions. Here, we present a transformable, reconfigurable robotic platform created by the integration of magnetically responsive soft composite matrices with deformable multifunctional electronics. Magnetic compounds engineered to undergo phase transition at a low temperature can readily achieve reversible magnetization and conduct various changes of motions and shapes. Thin and flexible electronic system designed with mechanical dynamics does not interfere with movements of the soft electronic robot, and the performances of wireless circuit, sensors, and devices are independent of a variety of activities, all of which are verified by theoretical studies. Demonstration of navigations and electronic operations in an artificial track highlights the potential of the integrated soft robot for on-demand, environments-responsive movements/metamorphoses, and optoelectrical detection and stimulation. Further improvements to a miniaturized, sophisticated system with material options enable in situ monitoring and treatment in envisioned areas such as biomedical implants.
Int. Journal of Mining Science and Technology (采矿与安全工程)•2025•DOI: 10.1016/j.ijmst.2025.03.009
In the process of deep engineering excavation, the mechanical properties of rock are significantly influenced by the coupled effects of water and high stress, which greatly increase construction difficulty. To more accurately investigate the impact of water disturbance on the failure process of dry rock under high stress and the failure mechanisms of saturated rock in underwater environments, a water environment test chamber and a prefabricated borehole specimen through-water device were designed. A series of experiments were conducted, including uniaxial tests, water-disturbed granite cylinder tests, and through-water disturbance tests on prefabricated hole square specimens. The results showed that the acoustic emission (AE) hits and accumulated energy after the through-water disturbance at the same time were 8.77 and 12.08 times higher than before the disturbance, respectively. And water disturbance increased the proportion of tensile failure and reduced the proportion of shear failure. A key observation was that AE events were mainly generated in the permeation areas near the borehole. The main reason was that under high stress, the weakening effect of water led to the failure of the local mineral structure of the rock, promoting crack extension and triggering overall instability. Notably, failure of the saturated specimens underwater was only observed when the applied load approached the saturation strength of the prefabricated hole square specimens. The study results provide an important theoretical basis for understanding the damage mechanism of water-disturbed rocks in deep engineering, and have significant implications for the design and construction of engineering.
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.
China Foundry•2025•DOI: 10.1007/s41230-024-4124-4
Near-eutectic Al-Si alloys are widely used in automotive manufacturing due to their superior wear resistance and high temperature performance. Because of high Si content, the grain refinement of near-eutectic Al-Si alloy has been a problem for many years. In this study, the effect of deep cryogenic treatment (DCT) on the microstructure and mechanical properties of Al-12Si-4Cu-2Ni-Mg alloy with addition of Al-Ti-C-B master alloy was fully investigated. Results show that the average grain size of the alloy is greatly reduced from 0.92 mm to 0.50 mm, and the eutectic Si and Al7Cu4Ni precipitates are spheroidized and refined in Al-12Si-4Cu-2Ni-Mg after DCT for 24 h and aging treatment. Thereby these changes of microstructures result in a significant increment of about 22.5% in elongation and a slight enhancement of about 6.8% in tensile strength. Moreover, the refinement of microstructure also significantly improves the fatigue life of the alloy.