High-gradient magnetic separation (HGMS) is widely used for weakly magnetic iron ores, yet its efficiency declines sharply for ultrafine hematite due to low magnetic responsiveness and poor capture probability. This study investigates how cross-linked corn starch (CLCS)-induced bridging aggregation enhances magnetic capture behavior in HGMS. The effects of slurry pH, CLCS dosage, and magnetic field intensity on aggregation behavior and magnetic capture efficiency were systematically examined. CLCS induced bridging aggregation and regulated aggregate architecture. While near-neutral conditions favored larger agglomerates, weakly alkaline conditions (pH approximate to 9) produced more compact and stable structures, increasing magnetic capture efficiency from 63.47% to 85.89%; excessive CLCS, however, caused steric hindrance and structural loosening. Magnetic capture experiments further revealed a transition from individual-particle capture to cooperative aggregate capture. Force-balance modeling demonstrates that structural enlargement enhances the ratio of magnetic force to hydrodynamic resistance, thereby improving capture probability. These findings clarify the cooperative magnetic capture mechanism of CLCS-induced hematite aggregates and provide mechanistic insight into the efficient recovery of ultrafine weakly magnetic hematite.

In the context of the escalating exhaustion of high-grade iron ore, the efficient development and utilization of refractory iron ore such as high-phosphorus oolitic hematite (HPOH) have significant strategic significance. After optimizing the technical parameters of flotation and leaching processes, this study conducted a comparative study of dephosphorization processes and analyzed the mineralogical characteristics of the samples using X-ray diffraction (XRD), scanning electron microscopy (SEM), and mineral liberation analyzer (MLA). The research results indicate that flotation process can effectively remove P-bearing minerals in the form of apatite but not phosphorus present in P-bearing iron minerals, under the high-temperature pretreatment temperature of 750 degrees C and selected conditions, flotation process can produce a concentrate with 62.26 % TFe grade, 0.33 % P content, and 54.02 % TFe recovery rate; In contrast, leaching process can effectively remove phosphorus present in Pbearing minerals, reduce the phosphorus content in concentrate, under the same pretreatment temperature and selected conditions, leaching concentrate with 63.10 % Fe grade, 0.27 % P content, and 67.81 % TFe recovery rate can be obtained through the leaching process, outperforming flotation. When the pretreatment temperature was raised to 1050 degrees C, under the optimal process conditions, leaching process achieved an iron concentrate with 62.16 % TFe grade, 0.13 % P content, and 88.04 % TFe recovery rate. The P content meets the industrial practical standards for iron concentrates used in the China's steel metallurgy industry (P content shall not exceed 0.2 %). This study provides a reference for the efficient development and utilization of HPOH.

The iron and steel production was accompanied by the emission of gaseous and solid phases, containing greenhouse gases and metal pollutants, respectively, constituting environmentally harmful by-products. In this work, waste blast furnace slag containing available alkaline oxides CaO and MgO was used to prepare via the method of co-precipitation and hydrothermal crystallization for carbon capture. The maximum CO2 adsorption capacity of the production reached 4.88 mmol center dot g(-1) under conditions of 75 vol% CO2 and 873 K. The CO2 adsorption process could be accurately described via the Avrami order kinetic model and Fractional order kinetic model with fitting degree exceeding 0.99. The Avrami kinetic model (A3) was identified as the most suitable for describing the CO2 desorption behavior. Additionally, the heating rate exerted little effect on the desorption rate but significantly shortened the desorption completion time. Chemical reactions and CO2 diffusion were identified as sequential limiting factors in the adsorption process, and the underlying reaction mechanism was further elucidated. To address the large volumes of solid slag, this work conducted a feasibility of using solid slag derivatives for flue gas capture, providing theoretical support for subsequent practical application.

Although starch is a low-cost, hydroxyl-rich green polymer depressant, it is poorly soluble in water and must be dissolved through thermal gelatinization or alkali treatment, which is contrary to the concept of green and healthy practices. Mechanical activation (MA) is a low-cost, pollution-free, and easily operable physical modification method for starch. This study systematically investigates the effect of MA on the properties of starch and its performance as a depressant in hematite flotation. The results show that MA disrupts the molecular structure of starch, increases its degree of branching, and generates two types of carbon-centered free radicals, thereby significantly improving the solubility of starch. Moderate MA markedly enhances the adsorption amount of starch on hematite surfaces and its depressing ability. However, excessive MA severely damages the molecular backbone of starch, leading to a loss of depressing performance. Molecular dynamics simulation further reveals that moderately activated MA starch exhibits the highest adsorption energy and a suitable band gap, corresponding to optimal hematite depression activity. These insights will facilitate the development of mechanical activation of depressant starch for mineral flotation and other industrial applications.

The efficient flotation separation of rare earth elements (REEs) from gangue minerals is crucial in mineral processing. This study synthesized a quaternary ammonium salt ionic liquid collector, tetrabutylammonium salicylhydroxamate (T-S), and investigated its performance in separating bastnaesite and fluorite. T-S was synthesized from salicylhydroxamic acid (SHA) and tetrabutylammonium chloride (TBAC), and its molecular structure was characterized using Fourier transform infrared (FTIR) spectroscopy. Microflotation tests indicate that T-S outperforms SHA and TBAC in both collecting ability and selectivity for bastnaesite. Adsorption, zeta potential, and infrared spectroscopy measurements reveal that T-S exhibits stronger adsorption on bastnaesite compared to SHA and TBAC. X-ray photoelectron spectroscopy (XPS) and molecular dynamics simulations (MDS) results confirm that chemical adsorption occurs between Ce on the bastnaesite surface and the -C(1/4O)NHOH groups of T-S. Moreover, the interaction between T-S and the bastnaesite surface is stronger than that with the fluorite surface. This work provides valuable insights for designing ionic liquid collectors for the flotation separation of bastnaesite and fluorite. (c) 2025 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Copper-bearing limonite is a valuable resource for both copper and iron, but achieving efficient recovery of both remains a key challenge. This study proposes a hydrogen mineral phase transformation pretreatment method, achieving efficient recovery of iron and the enhanced leaching of copper from copper-bearing limonite. Under the optimal experimental parameters, a magnetic concentrate with an iron grade of 63.74 % and an iron recovery rate of 98.46 % is obtained. Additionally, a total copper recovery rate of approximately 80 % is achieved through ammonia leaching of the magnetic concentrate and non-magnetic tailings, with the iron loss rate controlled below 1 %. During the hydrogen mineral phase transformation process, part of the ferric iron is reduced to ferrous iron, promoting the conversion of weakly magnetic limonite into strongly magnetic magnetite. Meanwhile, the formation of numerous cracks and pores on the surface of ore particles significantly enhances the effectiveness of subsequent ammonia leaching, providing a potentially viable pathway for the efficient and sustainable utilization of copper-bearing limonite.

This study systematically investigates the process optimization of hydrogen mineral phase transformation (HMPT) followed by low-intensity magnetic separation (LIMS) for iron recovery from iron tailings. The effects of key HMPT parameters on conversion efficiency and concentrate quality were examined, with phase transformation, microstructure evolution, and magnetic property enhancement characterized by XRD, SEM-EDS, VSM, and BPMA. Under optimal conditions, the concentrate yielded an iron grade of 70.17% and an iron recovery of 82.61%. Characterization revealed that the reduction process induced complete conversion of hematite and limonite to magnetite, substantially enhanced magnetic properties, and generated extensive cracks and pores on particle surfaces thereby facilitating reducing gas penetration and improving grindability. This hydrogen mineral phase transformation process offers a sustainable and efficient pathway for valorising iron tailings.

The efficient separation of fine-grained bastnaesite–monazite intergrowths remains a persistent challenge in the beneficiation of mixed rare-earth ores. In this study, we integrate micro-flotation with surface spectroscopy (FT-IR/XPS) and density functional theory (DFT) calculations to elucidate reagent–mineral interactions and to develop a selective flotation regime. Phthalic acid (PA) is identified as an effective selective collector, exhibiting substantially stronger interaction with bastnaesite than with monazite. Under weakly acidic conditions (pH ≈ 6.0) with aluminum sulfate as a conditioning reagent, closed-circuit flotation yields a bastnaesite concentrate grading 67.42 % REO at 89.15 % REO recovery, corresponding to ∼90.01 % bastnaesite purity. These results establish practical operating parameters for selective bastnaesite flotation from monazite and provide mechanistically informed guidance for collector selection in complex rare-earth flotation systems.

Selective separation of bastnaesite and monazite remains a rate-limiting step for lowering the environmental footprint of rare-earth production because of their closely related crystal chemistry and overlapping surface reactivity. This review synthesizes flotation, chemical leaching, and integrated beneficiation–hydrometallurgical flowsheets from the perspective of mineral surface chemistry and solid–liquid interfacial phenomena. Emphasis is placed on how crystallographic orientation and surface heterogeneity (facet exposure and defect states), surface hydroxylation/speciation, and electrical double-layer structure influence collector adsorption, reaction-layer (passivation) formation, and dissolution kinetics. On this basis, recent advances toward more sustainable processing are assessed, including structure-informed collector design, physically assisted leaching, flotation–leaching–solvent-extraction integration, and alternative solvent/lixiviant systems with a focus on recyclability and loss control. Opportunities for mechanism-driven interfacial engineering are then outlined, including facet-selective reagents, control of near-surface solution chemistry (pH, redox potential, and ligand activity), and co-separation strategies coupled with fluorine and Th/U risk management.

This study proposes a selective mineral phase transformation (MPT) pretreatment enhanced micro-flotation method. By optimizing the MPT conditions, the selectivity of benzo hydroxamic acid (BHA) toward the MPT products of bastnaesite is improved, enabling efficient separation of bastnaesite and monazite at the source. This approach enables diversion metallurgy and may reduce the environmental pollution caused by high-temperature concentrated sulfuric acid roasting of mixed rare earth concentrates. The results indicate that during the MPT process, an oxidizing thermal pretreatment conducted in air at the optimized condition of 700 degrees C for 10 min, bastnaesite (CeCO3F) was primarily transformed into Ce7O12, with cracks and pores appearing on particle surfaces and a significantly increased specific surface area compared with the raw ore, whereas monazite (CePO4) exhibited neither significant phase changes nor structural damage. In subsequent micro-flotation experiments with BHA as the collector, the two minerals exhibited distinct flotation behaviors under identical pH conditions. At pH 5.00, the recovery of Ce7O12 was significantly higher than that of CePO4. The artificial mixed ore experiments resulted in a Ce7O12 foam product with a REO grade of 70.74 % and a recovery of 96.39 %, and a monazite tank product with a REO grade of 49.46 % and a recovery of 75.52 %. Remarkably, these separations were achieved without the addition of any depressants. Mechanistic analysis revealed that after MPT treatment, more Ce4+ was exposed on the Ce7O12 surface, which competed with Ce3+ for adsorption and preferentially underwent chemical adsorption with the oxime group (-C--NOH) of BHA to form Ce-O chelate complexes. In contrast, the interaction between CePO4 and BHA was weak, thereby enabling efficient flotation separation of Ce7O12 and CePO4.

The Bayan Obo mixed rare earth concentrate is an important rare earth resource, yet its mainstream smelting processes have long faced the dilemma of balancing efficiency with environmental acceptability. In this study, a combined process of fluidized oxidative roasting and AlCl3-assisted hydrochloric acid leaching was employed to treat the mixed concentrate. The effects of process parameters on REO leaching efficiency were investigated, and the migration and transformation mechanisms of rare earths and fluorine during the oxidative roasting-hydrochloric acid leaching process were elucidated through thermodynamic analysis, phase evolution studies, and microstructural characterization. Under optimal conditions, the REO leaching efficiency reached 56.9% and the fluorine leaching efficiency reached 92.5%. The characterization revealed that fluidized roasting promoted the rapid decomposition of bastnaesite into REOF, RE2O3, and REF3, with partial oxidation of cerium to Ce7O12 and CeO2, while simultaneously optimizing the pore structure of the minerals. During the leaching process, REOF and RE2O3 were readily dissolved by hydrochloric acid, whereas REF3 and CeO2 remained in the residue. The addition of Al3+ effectively complexed F− and inhibited the formation of REF3 precipitates from dissolved RE3+ and F− in solution, thereby enabling the selective leaching of rare earths while monazite remained intact in the leach residue. By achieving selective rare earth leaching coupled with the targeted partitioning of fluorine, calcium, and thorium, this process offers theoretical support for resolving the long-standing dilemma between efficiency and environmental acceptability in conventional processes, and provides a viable technical pathway for the clean and graded utilization of the Bayan Obo mixed rare earth concentrate.

Bayan Obo Rare Earth Mine is the largest light rare earth resource worldwide, primarily extracts rare earth elements (REEs) from mixed RE concentrates with bastnaesite and monazite. Nevertheless, the adoption of the concentrated sulfuric acid roasting metallurgical process has resulted in damage to the environment. Therefore, this paper adopted the method of selective mineral phase transformation (MPT) followed by enhanced micro-flotation. By determining the optimal MPT conditions, the flotation recovery of bastnaesite-roasted products by the collector (phthalic acid, PA) is improved, and the enhanced separation of bastnaesite with monazite is realized. The results show that with the increase of roasting temperature and time, the bastnaesite decomposition product is CeOF and monazite does not change significantly. Subsequent micro-flotation exhibits a gradual decline in the PA consumption of bastnaesite-roasted products, while the flotation recovery of monazite-roasted products remains poor. The artificial mixed ore experiments result in a CeOF foam product with a content of 94.14% and a recovery of 85.80%, and a monazite tank product with a content of 73.53% and a recovery of 87.87%. Compared with the pre-roasting ore, the surface and interior of bastnaesite-roasted products develop numerous cracks and porosities, and no obvious structural damage is observed in monazite-roasted particles. As the roasting temperature increases, the mineral particles undergo recrystallization or closure, reducing the specific surface area of bastnaesite-roasted products and enhancing hydrophobicity, leading to diminished PA consumption. Fourier transform infrared and other flotation-relation tests show that PA is chemisorbed on the surface of CeOF. The MPT conditions are optimized in this study, which provides a reference for further advancing the efficient separation of bastnaesite and monazite.

The effect of oxidation roasting on the surface characteristics and flotation behavior of bastnaesite was investigated.Oxidation roasting experiments were performed at various temperatures,time,and O2 concentrations.The results indicated that increasing the temperature promoted the thermal decomposition of bastnaesite,resulting in the formation of Ce7O12,RE2O3,and REF3 as the main phases.Furthermore,oxidation roasting induced the formation of long,narrow,and nearly parallel cracks within the particles,increasing the porosity and facilitating partial particle fragmentation.During flotation,the concentration of dissolved rare earth ions increased significantly,and surface hydrolysis led to the formation of rare earth hydroxyl compounds.The complete decomposition of bastnaesite increased the required collector dosage to achieve a recovery above 85.00%.This increase might be attributed to the enhanced particle wettability,the altered adsorption mechanism of the collector,and the deeper penetration of the collector into the porous structure.

In the quest for sustainable and efficient extraction of valuable metals from complex ores, the development of advanced processing techniques is of paramount importance. This study introduces a groundbreaking and integrated process combining hydrogen mineral phase transformation (HMPT), grinding, magnetic separation, and leaching, specifically tailored for high iron oxide copper ores. This innovative approach not only significantly enhances the extraction efficiency but also addresses the challenges posed by the refractory nature of such ores. The HMPT technology represents a pivotal innovation in this process. It successfully increases the iron grade from 48.49 % to 51.29 % by promoting the reduction of hematite to magnetite and decomposing carbonate gangue minerals. This transformation not only improves the iron grade but also creates cracks and pores in the mineral particles, facilitating subsequent H2 reduction. Under optimized conditions (roasting temperature: 520 degrees C, roasting time: 20 min, H2 concentration: 30 %, gas flow rate: 500 mL/min), the process yields a magnetic concentrate with an iron grade of 65.64 % and an iron recovery rate of 98.10 %, while achieving a copper leaching rate of 99 %. Despite the initial challenges of closely intergrown iron minerals and gangue minerals that were difficult to separate, the integrated grinding and magnetic separation process effectively enhanced the separation efficiency of iron minerals from gangue minerals in magnetic concentrates, achieving highly efficient separation of magnetite from gangue minerals. The research findings provide robust theoretical and technical support for the exploitation and utilization of high iron oxide copper ore resources. Moreover, this innovative process offers a novel and practical solution for the development of other refractory ores with similar characteristics, thereby contributing to the advancement of sustainable mineral processing technologies.

The efficient utilization of fine weakly magnetic iron ores remains challenging due to weak interfacial interactions and poor floc stability, highlighting the necessity of interfacial structure engineering. Herein, three commercially available corn starches (CS) with well-established and representative molecular architectures-amylose (AMCS), amylopectin (APCS), and crosslinked corn starch (CLCS)-are employed to elucidate the structure-function relationships governing adsorption and bridging flocculation in hematite-quartz systems. The results reveal that molecular architecture regulates chain conformation, functional group accessibility, and steric effects, leading to distinct adsorption configurations and interparticle bridging behaviors. Linear AMCS forms compact adsorption layers with limited bridging capability, while highly branched APCS enhances surface interaction but suffers from steric hindrance that restricts floc stability. In contrast, CLCS tends to maintain more extended adsorption conformations, facilitating multipoint interactions and the formation of more robust floc networks, facilitating the formation of more robust floc networks with improved structural stability under dynamic HGMS conditions. Compared with direct magnetic separation of a-23 mu m mixture feed with an iron grade of 34.66%, the CLCS system achieved an iron grade of 61.67% and a recovery of 89.86%, corresponding to increases of 3.47% and 17.93%, respectively. This work establishes a mechanistic framework linking molecular architecture, adsorption conformation, and floc structure, and provides insights into the design of structurally tunable starch-based flocculants.

Currently, wearable health monitors face challenges such as complex manufacturing processes, trade-offs between flexibility and performance, limited multimodal integration, and issues like low sensitivity, high detection limits, and susceptibility to interference. To address these issues, we present a high-performance, antibacterial wearable sweat sensor based on a flexible Ag/PET electrode fabricated via a silver mirror reaction. Surface pretreatment with carboxyl groups optimizes silver nanoparticle distribution, resulting in excellent conductivity, mechanical stability, and efficient 3D sweat collection. The electrode is further functionalized with Cu-BTC through electrochemical cathodic deposition. The constructed sensors demonstrate high sensitivity for uric acid (32.4 μA mM−1 cm2) detection in artificial sweat (pH 5.5), with a wide linear range (10–300 μM), a low detection limit (1 μM), and strong anti-interference capability against common metabolites (the inhibition rate of over 62.3

Carboxymethyl chitosan (CMC), a macromolecular material with active hydroxyl and carboxyl groups, exhibits strong polarity and readily chelates with metal ions to form stable flocs. These properties make it a promising flocculant for recovering fine-grained iron oxide ores. In this study, CMCs with varying degrees of carboxymethyl substitution were synthesized to investigate their role in the magnetic separation of fine (-12.5 mu m) specularite and quartz, focusing on the relationship between flocculation and selectivity. Under optimized conditions, CMC significantly enhanced the magnetic separation recovery of fine specularite by promoting selective flocculation, increasing recovery from 71.98 % to 93.74 %. In the specularite-quartz binary system, CMC selectively adsorbed onto specularite, inducing its aggregation while exhibiting minimal interaction with quartz. This selective aggregation improved magnetic separation performance, raising the iron grade and recovery of the magnetic concentrate by 2.1 % and 18.19 %, respectively. Fourier Transform Infrared Spectroscopy (FTIR) and molecular dynamics simulation (MDS) revealed that CMC's carboxyl groups had a strong affinity for Fe atoms on the specularite surface, with adsorption energy nearly three times higher than on quartz. Sedimentation tests and polarized light microscopy confirmed that CMC promoted specularite aggregation via a bridging mechanism, increasing apparent particle size and improving separation efficiency. However, excessively long carbon chains sometimes entrapped quartz particles within specularite flocs, slightly reducing selectivity. These findings highlight CMC's potential as an efficient, selective flocculant for fine iron oxide recovery and its broader applicability in mineral processing and related fields.

As the drive for green mineral processing intensifies, enhancing separation efficiency while reducing environmental impacts remains a critical challenge. This study tackles the difficulty of separating chlorite and hematite minerals with similar surface properties by integrating micro-nanobubbles (MNBs) with a synergistic reagent system in flotation. Under optimized conditions (pH 11, alpha-BLA 200 mg/L, starch 10 mg/L, Ca2 + 150 mg/L), introducing MNBs increased the flotation recovery difference between the two single-minerals by 13.69 %. For artificial mixed ore, MNB flotation yielded an iron concentrate with a TFe grade of 64.89 %, representing a 35.06 % improvement in separation efficiency over conventional flotation. Starch formed a cap-type adsorption layer on hematite, inhibiting alpha-BLA adsorption, whereas, on chlorite, alpha-BLA can still adsorb after Ca2+ activation. This differential adsorption increases the hydrophobicity contrast between the two minerals, promoting selective chlorite-conventional flotation bubbles adhesion in the presence of MNBs. The resulting synergistic effect lowers the energy barrier for particle-bubble attachment. Kinetic analysis and in situ particle-bubble interaction visualization further confirms that MNBs enhance flotation rate by increasing the particle-bubble contact area, thereby enabling a low-energy, environmentally sustainable strategy for complex mineral systems.