The separation of quartz and albite, critically important for the industrial minerals sector, remains a formidable challenge due to their similar physicochemical properties. The industry-standard hydrofluoric acid method poses severe environmental and safety risks, while existing fluorine-free alternatives often require highly corrosive or alkaline conditions and suffer from issues like unstable froth. This study introduces a novel, sustainable flotation strategy using a synergistically combined collector system: a newly synthesized oligomeric surfactant, THQ-8, and sodium oleate (NaOL). The tailored hyperbranched structure of THQ-8 was designed to provide powerful collection while mitigating the persistent froth stability of conventional cationic collectors. Micro-flotation tests demonstrated that this mixed system achieved exceptional selectivity under a mild alkaline condition (pH 9.0) at a low total concentration (10 mg/L, NaOL/THQ-8 mass ratio = 1:2), recovering 95.04% of quartz while effectively depressing albite (recovery = 1.77%). In mixed mineral flotation with a 1:1 mass ratio of quartz to albite, the concentrate yielded 83.44% quartz recovery with an albite recovery of 13.90%, confirming the effectiveness under more realistic conditions. This performance successfully decouples efficient separation from extreme pH environments. A multi-faceted analytical approach, including contact angle measurements, FTIR, XPS, and AFM, revealed the adsorption mechanism. A robust "liquid film" with hydrophobic aggregates formed on quartz via synergistic chemisorption and hydrophobic co-assembly, whereas a competitive adsorption on albite led to a disordered, non-hydrophobic layer. This work establishes a new paradigm for quartz-albite separation, highlighting the immense potential of oligomeric surfactant design in developing efficient and environmentally benign mineral processing reagents.

The efficient flotation separation of lepidolite from quartz and albite remains challenging in conventional cationic systems, primarily due to poor selectivity and excessive foam stability. To address these issues, a novel oligomeric surfactant, THQ-8, was synthesized and investigated as a potential collector for lepidolite flotation. Micro-flotation results confirmed the superior selectivity of THQ-8, with recoveries of 95.94% for lepidolite versus only 6.32% for albite and 9.57% for quartz, enabling efficient separation. This performance surpassed that of the traditional collector dodecylamine (DDA), which required a highly acidic pulp (pH 2.0), and the Gemini collector PDDA, which lacked selectivity. Complementing this selectivity, also produced foam with markedly lower stability and height than both counterparts, indicating favorable froth properties for mineral processing. A multi-faceted adsorption mechanism study, incorporating contact angle measurements, FTIR, XPS, and AFM, confirmed that THQ-8 selectively chemisorbs onto the lepidolite surface. The primary mechanism involves coordination between the electron-donating nitrogen atoms in its large conjugated structure and the aluminum sites in the natural Al-F and AlF3/AlFx layers of lepidolite. In contrast, only weak physisorption or hydrogen bonding occurred on albite, and virtually no adsorption was detected on quartz. This work establishes THQ-8 as a highly effective and selective collector for lepidolite, operating under milder process conditions and overcoming the key limitations of foam stability and corrosion associated with conventional reagents.

Metal ions play a significant role in the flotation process of muscovite minerals. As a common metal ion activator, Mg2+ is often employed in the flotation of muscovite minerals with NaOL, whereas the regulation mechanism remains unclear. The flotation behaviour and regulation mechanism of muscovite and quartz in the combination of Mg2+ and NaOL system are investigated by micro-flotation, solution chemical calculations, zeta potential, FTIR, and XPS tests. Flotation results indicated that compared with sequential addition method, the pre-mixed addition method of Mg2+ and NaOL could deteriorate the recovery of muscovite from 82.16 % to 49.82 %, while the recovery of quartz always remained at an extremely low level. Zeta potential and FTIR analysis results revealed that the complex collector formed by the pre-mixed of Mg2+ and NaOL had a weaker chemical adsorption intensity on the muscovite surface than that in the sequential addition method. Moreover, regardless of the addition method of Mg2+ and NaOL used, the adsorption intensity of NaOL on the quartz surface was much lower than that on muscovite. XPS analysis results confirmed that the activation of muscovite flotation by Mg2+ in NaOL system mainly relied on the pre-adsorption of Mg2+ on the muscovite surface to form active sites, which then promoted the adsorption of NaOL. Furthermore, the adsorption of a complex collector formed by the pre-mixed of Mg2+ and NaOL on the muscovite surface played a synergistic role.

Sodium oleate (NaOL) is widely used as a collector in spodumene flotation, but its performance often declines under low-temperature conditions. To elucidate the mechanisms underlying this temperature dependence, we integrated micro-flotation tests, molecular dynamics (MD) simulations, bubble dynamics analysis, dynamic contact angle measurements, and bubble-mineral adhesion observations. Over the range of 5-35 degrees C, spodumene recovery at low NaOL concentration increased from 20.56 % to 67.06 % (+226 %). Elevated temperatures reduced NaOL solution surface tension, producing smaller, more stable bubbles with lower rising velocity. MD simulations revealed that the mean squared displacement diffusion coefficient of NaOL molecules rose from 0.00199 & Aring;2/ps to 0.00561 & Aring;2/ps, indicating enhanced molecular mobility and improved interaction with mineral surfaces. Static contact angles on the (110) surface increased from 66.37 degrees to 78.58 degrees, while three-phase contact time decreased from 810.8 ms to 262.8 ms, accelerating bubble-mineral attachment. These temperature-driven enhancements in interfacial properties, collector adsorption, and bubble stability collectively improve flotation efficiency. The results provide molecular-level insights and practical guidelines for designing low-temperature-resistant collectors and optimizing spodumene flotation processes, contributing to more efficient lithium resource recovery in challenging environments.

Spodumene frequently coexists with albite, presenting significant challenges in their separation due to their closely similar physical and chemical characteristics. In the present study, a noval reagent scheme has been proposed for the selective activation of spodumene by Zn2+ ions within the sodium oleate (NaOL) system. This innovative approach aims to enhance the efficiency of spodumene activation, thereby improving overall process performance. Micro-flotation experiments were conducted to investigate the recovery of spodumene and albite. The results show a high spodumene recovery of 90.33 % at pH 10.0, with the addition of 2 x 10-4 mol/L Zn2+ ions and NaOL. In contrast, the recovery of albite remains low at 17.93 %. Artificial mixed mineral experiments have demonstrated a remarkable separation efficiency of spodumene and albite. The activation mechanisms were explored by contact angle, solution chemistry analysis, zeta potential, Fourier Transform Infrared (FTIR) Spectroscopy, and X-ray Photoelectron Spectroscopy (XPS). The findings reveal that spodumene exhibits enhanced hydrophobicity compared to albite after treatment with Zn2+ ions and NaOL. It is also observed that Zn2+ ions activate spodumene by bonding with oxygen atoms on the spodumene surface and forming precipitates on the surface of spodumene within the optimal pH range. Unlike the spodumene surface, Zn2+ ions form weak bonds with the albite surface. Following the activation of Zn2+ ions, NaOL demonstrates a remarkable capacity to absorb on the surface of spodumene. This phenomenon leads to a substantial disparity in the floatability of spodumene and albite, consequently facilitating their effective flotation separation.

The effect of the iodine value of oleic acid on the flotation performance of oleic acid-based collectors for spodumene was investigated in this study. The adsorption behaviors of oleic acid solutions with varying iodine values on spodumene surfaces were analyzed using flotation experiments, Zeta potential measurement, adsorption amount measurement, X-ray photoelectron spectroscopy, FTIR measurements, molecular structure analysis, frontier orbital theory, and molecular dynamics simulations. Flotation tests on artificial mixed minerals reveal that as the iodine value of oleic acid increases from 80 to 140, the Li2O recovery in the concentrate progressively increases from 45.57 % to 64.74 %. This indicates that a higher iodine value significantly enhances Li2O recovery. The results of Zeta potential, adsorption amount, and XPS analyses confirm that the carboxyl groups of higher-iodine-value oleic acids exhibit stronger chemical adsorption onto Al sites on the spodumene surface. FTIR analysis demonstrates that during the interaction of high-iodine-value oleic acid solutions with spodumene, linoleic acid molecules are adsorbed on the spodumene surface. Structural and orbital analysis further reveals that linoleic acid exhibits a stronger interaction with the mineral surface, facilitating more effective adsorption. Molecular dynamics simulations suggest that the increased linoleic acid content leads to a higher concentration of reagent molecules on the spodumene surface, thereby improving flotation performance.

Building upon our previous research, a novel amphoteric collector, Lauramide diethanolamine (LDEA), was introduced to further investigate the effect of cationic reagent structure on the flotation performance of sodium oleate (NaOL)-based combined collectors for spodumene. Micro-flotation tests demonstrated that NaOL/LDEA achieved the highest selectivity among the evaluated systems, with a Li2O grade of 5.53 % and recovery of 83.25 %, while reducing feldspar recovery to 11.03 % under optimal conditions (pH 8, molar ratio 6:1, concentration 75 mg/L). Total organic carbon (TOC) analysis showed that the adsorption amount of NaOL/LDEA on spodumene was 2.608 x 10-6 mol/g, significantly higher than that on feldspar (0.894 x 10-6 mol/g). Frontier molecular orbital analysis revealed a lower HOMO-LUMO energy gap (2.659 eV) between LDEA and the spodumene (110) surface, facilitating electron transfer. Molecular dynamics simulations further confirmed stronger interaction energy (-3.12 kcal & sdot;mol-1 & sdot;& Aring;-2) and higher mass density (0.681 g/cm3) of LDEA on spodumene compared to feldspar. These findings suggest that the nitrogen and oxygen atoms in LDEA, particularly those within the amide group, enable specific interaction with Al-O sites on the spodumene surface, contributing to its superior selectivity and structural adaptability.

Metal ions commonly emerge as effective activators in the flotation of silicate minerals using anionic collectors, yet the underlying interaction mechanisms remain not well-understood. In this paper, the activation role of magnesium ions (Mg2+) in the flotation of lepidolite, using sodium oleate (NaOL) as the collector, was systematically explored. Flotation tests on single minerals reveal that the activation capacity for lepidolite of Mg2+ significantly outperforms Ca2+, achieving a remarkable recovery efficiency of over 85 % at pH 8. In contrast, the recovery of quartz remains consistently below 15 % across the tested conditions. Experiments with artificially mixed minerals demonstrate that a satisfactory flotation separation of lepidolite from quartz is achieved using Mg2+/NaOL with a molar ratio of 1:3 at pH 8, resulting in an impressive selectivity index (SI) of 18.84. Fourier transform infrared spectroscopy (FTIR) analysis and zeta potential results indicate that NaOL effectively adsorbs on the Mg2+-activated lepidolite surface through electrostatic attraction. Adsorption tests show that NaOL enhances the adsorption equilibrium of Mg2+ on the lepidolite surface, potentially due to the formation and adsorption of Mg-OOCR colloid. Furthermore, the interaction of Mg2+ with NaOL and lepidolite surface is more robust than that of Ca2+, while the single metal ions exhibit negligible activation effects on quartz. X-ray photoelectron spectroscopy (XPS) analysis further indicates that NaOL primarily interacts with O, F, and Al sites on the lepidolite surface under the mediation of the Mg atom.

A new combined collector of NaOL and 1,12-Dodecanediamine (DA122) was used for efficient flotation of spodumene from feldspar. The disparities in mineral flotation efficacy between the combined collectors of NaOL/ 1,12-Dodecanediamine and NaOL/Dodecylamine (DDA), as well as the underlying mechanisms, were comprehensively analyzed by the measurements of flotation experiments, surface tension, adsorption amount measurement, structure and frontier molecular orbital analysis and adsorption model calculation. The results of mixed minerals micro-flotation indicate that the Li2O 2 O recovery of 91.64% was achieved using NaOL and DA122 combined collector, which represents an 11.54 % increase in Li2O 2 O recovery compared to using the NaOL and DDA combined collector. NaOL and DA122 combined collector exhibits a lower critical micelle concentration (CMC) and the greater adsorption amount on the surface of spodumene. NaOL and DA122 combined collector demonstrates higher reactivity and adsorption energy on the surface of spodumene, resulting in higher hydrophobicity of spodumene because DA122 possesses stronger ability to lose electrons than DDA, thus leading to higher recovery of spodumene.

This study investigates the negative impact of temperature on spodumene flotation from the perspective of the gas–liquid interface of sodium oleate (NaOL) solutions. Micro-flotation tests revealed a significant decrease in the flotation recovery of spodumene when NaOL was employed as a collector, dropping from 55.3% at 305.4 K to 5.1% at 277.3 K as the temperature decreased. A strong linear correlation between the surface tension of the NaOL solution and temperature was established. As the temperature decreased, the surface tension of 6 × 10−5 mol/L NaOL increased from 37.88 mN/m at 294.9 K to 40.71 mN/m at 281.9 K, while its critical micelle concentration decreased from 9.49 × 10−4 mol/L at 305.0 K to 6.85 × 10−4 mol/L at 288.0 K. Additionally, molecular dynamics (MD) simulations indicated that a decrease in temperature resulted in an enhancement of intermolecular action forces, a more compacted interfacial structure, and weakened molecular thermal motion at the gas–liquid interface of the NaOL solution. These variations were found to be the main reason for the rise in the surface tension of the NaOL solution as the temperature decreased, which in turn lowered its efficiency, resulting in a decrease in the flotation efficiency of spodumene.

Phosphogypsum (PG) is a solid waste generated during the "wet phosphoric acid process." The phosphorus (P) impurities and low-value-added recycling products seriously constrain PG re-utilization, which results in its massive accumulation and thus occupies large land areas and poses a severe pollution threat to the environment. In this study, by regulating gypsum crystal and P species in CaCl2-HCl solutions under mild conditions, efficient removal of P impurities (leaching efficiency of 97.78%) and synchronous preparation of highstrength alpha-CaSO4 center dot 0.5H(2)O (alpha-HH) (compressive strength of 35.2 MPa) from PG were achieved during the phase transition from CaSO4 center dot 2H(2)O (DH) to alpha-HH, which was a reaction of DH dissolution, followed by alpha-HH crystallization. The co-crystalline Pwas fully released during the dissolution process, whichwas necessary to efficiently eliminate P impurities. HCl dissolved the released P and transformed them into the protonated specie (H3PO4) with less similarity to SO4 (2-), which prevented the recombination of the released P with gypsum during the crystallization process. Furthermore, alpha-HH morphology and size were controlled by seeding in the mixed solutions. The formation of regular large aHH crystals with a low-specific surface area significantly weakened the surface adsorption of P in solutions and further increased the P leaching efficiency. More importantly, the large stumpy a-HHwas identified as high-strength gypsumwith high added value. This work would provide innovative guidance to efficiently remove impurities from gypsum and pioneer a cost- effective approach for clean and high-value utilization of industrial gypsum residues.

In this paper, the flotation separation of quartz and feldspar was studied with CaCl2 as activators and mixed sodium oleate/ dodecylamine (NaOL/DDA) collectors under alkaline condition, and the action mechanism of mixed NaOL/DDA collectors on the quartz and feldspar surfaces were systematically explored. The results of micro-flotation test showed that there were 90.98% quartz and 13.08% feldspar were floated with 0.5 mmol/L CaCl2 and 2.8 mmol/L mixed NaOL/DDA collectors with molar ratio of 8/1 at pH 10.0. And the artificial mixed minerals flotation manifested these two minerals were able to efficient separation with CaCl2 and mixed NaOL/ DDA collectors at pH 10 similar to 11. These outcomes indicated that DDA could increase recovery of quartz obviously and reduce about a half dosage of NaOL (from 0.5 mmol/L to 0.25 mmol/L) in flotation under alkaline condition; Meanwhile, mixed NaOL/DDA collectors were able to decreased the flotation separation pH from 12 to 10 on quartz and feldspar. Infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) results revealed that when NaOL collector was added alone, it could adsorb on activated quartz surface but hardly detected on feldspar surface at pH 10. However, they all were found on both quartz and felspar surface when mixed NaOL/ DDA collectors were introduced as collectors. Quartz microcrystal balance with dissipation (QCM-D) experiment confirmed that mixed NaOL/DDA collectors showed a higher adsorption mass and more stable adsorption layer on quartz compared with NaOL was introduced as collector alone. In addition, whether CaCl2, NaOL or mixed NaOL/DDA, the adsorption mass on quartz sensor were larger than that on feldspar senor, which might cause difference of hydrophobicity on the surface of quartz and feldspar in flotation. The above experiments showed that the mixed NaOL/DDA collectors can significantly improve hydrophobic difference between quartz and feldspar after activating with CaCl2 and expand the floated pH range of quartz compared with using NaOL as collector alone, which were efficient reagents to separate quartz and feldspar in flotation.

Granite tailings are rich in quartz and feldspar with high recycling value. However, quartz-feldspar separation usually adds sulfuric acid and hydrofluoric acid, which inevitably leads to equipment corrosion and environmental pollution. This study introduced an alkaline-based flotation method to treat granite tailings. In this approach, mica was first floated by adding Na2CO3 as pH adjuster and sodium oleate/octanol with mass ratio 9/1 (NaOT) and dodecylamine acetate as mixed collector. Then, the quartz-feldspar separation was achieved using NaOH as pH adjuster, MgCl2 as activator, and NaOT as collector. The results of the flotation test showed that the yield of quartz products was 24.51% with a grade of 96.04% SiO2, and the yield of feldspar products was 41.77% with a grade of 14.06% K2O and Na2O. The economic analysis demonstrated that the flotation process in this study yields a profit of 50.96 USD per ton of treated tailings. Overall, this approach possesses the advantages of excellent selectivity, obvious economic efficiency, and environmental friendliness, making it highly suitable for industrial applications with immense potential.

Metal cations have great effects on the flotation of silicate minerals whereas the interaction mechanism is unclear. Single mineral flotation demonstrated that the recovery of biotite rose to 94.69% and 96.41%, and that of quartz declined to 1.21% and 2.01% after introducing small amounts of Ca2+ and Mg2+, respectively. Artificial mixed mineral tests indicated that Ca2+ and Mg2+ could increase the Gaudin's selectivity index by 11.98 and 11.37, respectively, compared with 11.53 without metal ions. QCM-D measurements revealed that sodium oleate (NaOL) and dodecylamine (DDA) could co-absorb on the biotite surface, and a rigid DDA layer formed on these surfaces with/without metal ions. Moreover, the adsorption of NaOL on the biotite surface could be enhanced by Mg2+, from dissipated to rigid adsorption, while that on the quartz surface was barely influenced. Surface chemistry analysis confirmed that metal ions acted as adsorption bridges between mineral surfaces and carboxylate, thereby enhancing the adsorption of collectors.

Feldspar and quartz are similar in composition and structure, and hence, they exhibit low flotation separation efficiency in acid or alkaline conditions and while using the traditional reagents scheme. In this study, hydroxypropyl starch (HPS) was introduced as a novel depressant in the flotation separation of quartz from feldspar. Magnesium chloride (MgCl2) was used as an activator and sodium oleate (NaOL) as a collector. The micro-flotation tests showed that the pulp pH had a decisive influence on the flotation separation of quartz from feldspar. At pH 10.50, quartz and feldspar could be partially separated without depressants. However, some amount of feldspar (10%-20%) remained afloat, resulting in a low quartz grade in the concentrate. The flotation of feldspar was selectively depressed using HPS as depressant, leading to a much higher separation efficiency, and the selectivity index increased from 4.57 to 7.52. The high selective performance of HPS depressant was also confirmed via the bench-scale flotation tests, and the yield of the feldspar products increased from 22.70% to 30.20%, while the grade of K2O + Na2O increased from 13.73% to 14.35%. The inhibitory mechanisms of feldspar and quartz were analyzed through Raman and X-ray photoelectron spectroscopy. These results indicated that HPS leaned towards complex formations with Al-sites on the surface of feldspar, thereby reducing the adsorption of NaOL and inhibiting the flotation of feldspar. Therefore, HPS could be used as a feldspar depressant in flotation separation quartz from feldspar.

随着锂资源需求的日益增大,作为锂资源提取的主要来源,锂辉石的选别技术需要不断发展与完善.如何扩大锂辉石与脉石矿物的可浮性差异,是提高锂辉石浮选效率的关键.概括分析了锂辉石与脉石矿物晶面的各向异性及近年来锂辉石矿浮选研究的最新进展.分析表明:锂辉石解理面具有很强的各向异性和表面组分选择性溶蚀行为.调控锂辉石优势解理面比例和表面组分选择性溶蚀及阴阳离子组合捕收剂的使用,可进一步强化锂辉石的浮选,同时加强脉石矿物选择性抑制剂的开发,这些将成为锂辉石矿浮选工艺研究的重要方向.

Surface dissolution behaviors of spodumene, feldspar, and quartz, and its influences on their surface properties and flotation separation were investigated when pretreated in deionized water (DI water), NaOH solution and HCl solution individually. The surface components of minerals, such as Si and Al, had shown different dissolution behaviors. In the presence of sodium oleate, the contact angle of spodumene increased after pretreated by the NaOH solution, but it decreased after pretreated by the HCl solution. The dissolution of Si from spodumene is helpful to the adsorption of sodium oleate and the flotation separation of spodumene from silicates, but the dissolution of Al has the opposite effect.

Bauxite residue (BR), a by-product of the industrial production of alumina, has raised environmental concerns in the last decades, due to the presence of high amounts of alkali and various heavy metal ions. Limited studies on the application of abandoned BR with massive consumption have been reported. In this study, the possibility of the revegetation using ryegrass growing on BR was discussed mainly through the growth indications and transfer of heavy metal ions in BR and plants. In the pot trails, ryegrass was seeded on BR, de-alkali BR, with (DBRO) or without (DBR) organic fertilizer, respectively. The results indicated that the remediation of bauxite residue can be achieved through de-alkali with acid neutralization. Elemental analysis indicated that the elements, except for Fe, Mn and Pb, were stable in plant roots, and ryegrass could hardly absorb Cd. But, some heavy metals such as Cu enriched in plants, which should be noted in revegetation on bauxite residue.