The high-value utilization of brucite waste remains a challenge in mineral resource recycling. The application of mineral-derived anhydrous MgCO₃ (MC) as a filler in hydrophobic polymer matrices is often limited by poor interfacial compatibility. In this study, brucite waste is converted into surface-modified MC with enhanced hydrophobicity via a one-pot process. During the process, l-ascorbic acid (L-ASA) promotes Mg2+ release by weakening OMg bonds and supplies CO₂ upon decomposition for in-situ carbonation. Concurrently, hydrolyzed hexadecyltrimethoxysilane (HDTMS) is grafted onto the MC surface through Si–O–Mg coordination and hydrogen bonding, forming a dense hydrophobic layer. The resulting particles exhibit a well-defined spindle-like morphology (~6 μm in length and ~ 2 μm in width) and a water contact angle of 125°. The surface organic carbon content reaches 2.44 mg/g, approximately fivefold higher than that of unmodified MC. The process also leads to controlled structural evolution while enabling simultaneous surface functionalization. These improved surface properties are expected to enhance compatibility with hydrophobic polymer matrices. Carbonaceous byproducts from L-ASA decomposition can be recovered as adsorbent precursors. The obtained MC therefore shows strong potential as a functional filler with improved dispersion and interfacial compatibility.

During the separation of moist coal using a gas-solid fluidized bed, heavy-medium adhesion notably deteriorates separation performance. In this study, fluidization tests, pressure drop measurements, and sink-float tests were employed to systematically investigate critical fluidization characteristics of the moist bed, bed-density stability, and feed-coal separation behavior. The mechanism through which hot-air injection influences heavy-medium adhesion and separation performance of moist coal was comprehensively analyzed. Results indicate that heavy-medium adhesion to fine coal particles is more sensitive to moisture content. At a bed temperature of 40 degrees C, heavy-medium adhesion on the surface of moist lump coal of various particle sizes can be effectively suppressed. Following hot-air injection, the total misplaced material content for separated coal fractions of 13-25 mm and 6-13 mm decreases by 6.63% and 10.65%, respectively. This study clarifies the beneficial role of hot air in mitigating heavy medium adhesion during fluidized-bed separation of moist coal, providing theoretical support and technical guidance for the high-efficiency separation of moist coal.

The flotation removal of silica impurities from phosphate ore is a prerequisite for its subsequent processing and utilization. However, current cationic collectors used for silica removal in phosphate ore flotation suffer from low selectivity, hindering efficient apatite-quartz separation. This study investigated the efficient separation of quartz and apatite using amide-based gemini quaternary ammonium salt GS-A6 as a high-efficiency collector in reverse flotation. Through systematic flotation investigations and characterization analyses, the separation performance of GS-A6 was evaluated, and its adsorption behavior on mineral surfaces was elucidated. Flotation results indicate that under pH 7.0 and 3.0 mg/L GS-A6, a recovery of 94.68% apatite concentrate, P2O5 grade of 39.98%, and separation efficiency of 91.51% was achieved, facilitating efficient separation of apatite from quartz. Surface wettability and SEM-EDS measurements indicate that GS-A6 strongly adsorbs onto quartz surfaces rather than apatite, selectively enhancing quartz surface hydrophobicity and thereby achieving excellent floatability of quartz. Zeta potential, FT-IR, and XPS analyses reveal that GS-A6 ' s strong adsorption on quartz surfaces stems from intense electrostatic attraction between its cations and negatively charged quartz surfaces, coupled with hydrogen bonding between the-C=O and N-H groups of the amide moiety in GS-A6 molecules and quartz surfaces. Consequently, GS-A6 functions as an efficient quartz collector in the purification of siliceous phosphate ores through reverse flotation.

Coal gasification fine slag (GFS), as a carbon-rich solid waste, presents significant importance for the recovery and reuse of its combustible carbon. However, the carbon surface has a developed pore structure, which leads to high flotation reagent consumption and low separation efficiency. To effectively recover carbon from GFS, this study used talc as a pore-plugging material to plug carbon’s surface pores thereby improving the carbon recovery via direct flotation. Scanning electron microscope-energy dispersive spectrometer (SEM-EDS) and mercury intrusion porosimetry (MIP) indicated that talc could successfully plug carbon’s surface pores. Flotation experiments showed that after talc plugging, the carbon recovery increased by 12.50%. Flotation kinetics analysis showed that after talc plugged the pores, the cumulative carbon recovery was improved, and the carbon-ash separation process in GFS conformed to the Modified Kelsall model. Wettability characterization and zeta potential measurements showed that after talc plugged the carbon pores, kerosene’s adsorption effect onto the surface of carbon was enhanced, thereby expanding the hydrophobicity difference between the carbon and the ash. Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS) confirmed that talc plugging carbon pores enhanced kerosene’s widespread adsorption onto the carbon surface. Based on these findings, talc, serving as a pore-plugging material, can boost the flotation recovery of combustible carbon from GFS.

To address the poor selectivity of traditional cationic collectors toward the flotation separation of apatite and quartz, which causes low separation efficiency of two minerals. To enhance the removal of quartz from apatite, a novel palmitic acid derivative amide quaternary ammonium salt PATC was introduced as a quartz collector. The selectivity and adsorption mechanism of PATC towards quartz during apatite-quartz flotation separation were investigated. Micro-flotation tests and flotation kinetics analysis indicated that PATC was excellent at collecting quartz but not apatite. Flotation separation tests showed that, under optimal conditions, the process achieved an apatite concentrate recovery of 96.18% ± 0.17%, a P2O5 grade of 40.19 ± 0.21%, a quartz removal of 96.35 ± 1.14%, with a separation efficiency of 96.42 ± 0.11%. This enables efficient desilication and purification of medium-to-low grade apatite. Surface wettability and SEM-EDS analyses demonstrated that PATC exhibits a preferential adsorption affinity for quartz over apatite, significantly enhancing the hydrophobicity of the quartz surface and thereby imparting excellent floatability. Comprehensive characterizations via zeta potential, FT-IR, and XPS clarified that the preferential adsorption of PATC onto quartz primarily resulted from the synergistic interaction of electrostatic attraction and hydrogen bonding between the functional groups (-N+(CH3)3 and -CONH) in PATC and the components (Si-O- and Si-OH) on the quartz surface. Consequently, PATC can serve as an efficient quartz collector during the reverse flotation desilication process of high-silica phosphate ore.

Background: Removing silicate impurities from low-grade phosphate ore is an essential pretreatment for producing agricultural phosphate fertilizers, but traditional cationic collectors are limited by low solubility and poor selectivity, which reduce the efficiency of reverse flotation desilication. Therefore, there is an urgent need for highly efficient, low-cost collectors.Methods: Flotation experiments, wettability investigations, zeta potential detection, XPS, FTIR, SEM-EDS, and EDLVO theoretical calculation were employed to assess the collection selectivity and uncover interfacial regulation mechanisms of branched dodecyl polyoxyethylene etheramine (BDPE) in the effective desilication of apatite. Significant findings: BDPE selectively collected K-feldspar, widening its floatability gap with apatite and enabling effective desilication of apatite. This achieved an apatite recovery of 86.71%, a K-feldspar removal rate of 92.65%, and a selectivity index (SI) of 9.07, which was 4.16 times that of the conventional collector dodecylamine (DDA). Surface analysis indicated that BDPE was selectively adsorbed onto the K-feldspar surface due to electrostatic attraction and hydrogen bonding, significantly enhancing the hydrophobicity of the K-feldspar surface. EDLVO theoretical calculations further confirmed that BDPE switched the interaction force between Kfeldspar and bubbles from repulsive to attractive, improving the floatability of K-feldspar. Thus, BDPE is an effective K-feldspar collector for flotation desilication of phosphate ore.

This study investigates the impact of n-alkanes and n-alkylbenzenes with varying carbon chain lengths on the flotation performance and bubble adhesion mechanisms of microfine flake graphite (MFG). The experimental results demonstrate that the structure of oil-based collectors significantly influences the flotation efficiency of MFG. Specifically, under conditions of 500 mg/L concentration and pH = 6, the flotation recovery of MFG after treatment with long-chain n-alkylbenzenes increased by 30.92 percentage points compared to treatment with nalkanes of the same carbon chain length, and by 32.29 percentage points compared to kerosene. Zeta potential measurements indicate that, compared to n-alkanes, MFG treated with n-alkylbenzenes exhibits a greater shift in surface potential, suggesting stronger adsorption of n-alkylbenzenes on the mineral surface. Contact angle, wrapping angle, and induction time tests show that n-alkylbenzenes with longer carbon chains significantly enhance the hydrophobicity of MFG, accelerate the adhesion process between bubbles and the mineral, and form a more stable three-phase interface on the graphite surface. XPS analysis reveals that, after treatment with collectors, the content of C-C/C-H groups on the mineral surface increases gradually with the increase in the carbon chain length of the collector. Notably, after treatment with n-octylbenzene, the content of hydrophobic groups on the surface increased by 6.32 percentage points, while n-tetradecane only increased the hydrophobic groups by 4.15 percentage points. These findings suggest that n-alkylbenzenes with longer carbon chains can significantly enhance the hydrophobicity of MFG, effectively disrupt the hydration film on the mineral surface, and accelerate the adhesion process between the mineral and bubbles, thereby substantially improving the floatability of MFG. This study offers a novel approach for developing highly efficient MFG collectors.

Purification and pre-concentration of coal-hosted graphite ores help ensure their subsequent processing applications. In this study, the pre-concentration effects of coal-hosted graphite ore by triboelectric separation were examined by changing the shape of the friction medium rods. The effects of friction medium rod shapes on the charge characteristics of graphite and quartz were examined by numerical simulations and charge-to-mass ratio tests. In addition, the effects of rotation speed, electrode voltage, and feed rate on the pre-concentration of coal-hosted graphite ore were investigated by triboelectric separation. The results showed that graphite and quartz were best charged by using rhombic shaped medium rods. Compared with cylindrical and sawtooth structures, the rhombic structure increased the collision probability between particles and medium robs, widened the charge-to-mass ratio gap between graphite and quartz, and strengthened the pre-concentration of coal-hosted graphite ore by triboelectric separation. Under optimal operating conditions, the separation efficiency of 0.25-0.5, 0.125-0.25, and 0.074-0.125 mm coal-hosted graphite ores were 27.14 %, 38.02 %, and 52.51 %, respectively, representing improvements of 7.98 %, 10.12 %, and 12.05 % compared to cylindrical medium rods. Our study can provide important guidance for effective enrichment of coal-hosted graphite via triboelectric separation.

Coal-series kaolin has emerged as a focal point in resource recovery research due to its potential for rare earth elements (REEs) enrichment. This study employed a combined method of (NH4)2SO4 roasting and deep eutectic solvent (DES) leaching to enrich REEs within the material. The operating parameters were optimized, and multiple characterization techniques were utilized to elucidate the synergistic interaction mechanism. Analysis via sequential chemical extraction revealed that REEs mainly exist in the form of silicate/aluminosilicate phases. FESEM, thermodynamic study, TG-DTG, FT-IR, and XRD analyses indicate (NH4)2SO4 calcination causes kaolinite to release the encapsulated REEs, thus facilitating their contact with the DES. The H+ ions generated by DES ionization then dissolve the exposed REEs into ionic species, which subsequently form stable complexes with Cl and DL-malate anions in the liquid phase. Under optimized conditions, more than 80 % of the target REEs (i. e., Y, Nd, Ce, La, and Pr) were leached. Leaching kinetic analysis demonstrates that interfacial chemical reactions govern the DES leaching process. This method achieves efficient leaching of REEs from coal-series kaolin, providing a valuable technical reference for recovering REEs from coal-series mineral resources.

The high moisture content in coal gasification fine slag (CGFS) has a significant restrictive effect on the recovery and utilization of residual carbon within the fine slag. This study proposes a CTAC/PDADMAC/NPAM synergistic system and systematically investigates its role in the flocculation-sedimentation-dewatering of CGFS. The study reveals that CTAC promotes particle agglomeration via hydrophobic modification, PDADMAC exerts dual effects of charge neutralization and bridging, and NPAM enhances floc structure by reconstructing hydrogen bond networks. FTIR and XPS analyses confirmed that: (1) CTAC formed an adsorption layer on CGFS particle surfaces via electrostatic interaction or van der Waals forces; (2) PDADMAC weakened the hydrogen bond interactions between hydroxyl groups on the CGFS surface and water molecules by virtue of competitive adsorption and spatial site-blocking effects; (3) the amide group (-CONH2) of NPAM formed intermolecular hydrogen bonds with CGFS silanol groups (Si-OH). Using the Box-Behnken design (BBD) to optimize the reagent ratio, it was found that the optimal treatment effect was achieved when CTAC (4.92 kg/t), PDADMAC (205.05 g/t), and NPAM (101.52 g/t) acted synergistically: the supernatant turbidity decreased to 2.331 NTU (a 99.26 % reduction), the filter cake moisture content reached 51.07 % (a 10.17 % reduction), and the sedimentation rate reached 33.78 cm/min. This study establishes a synergistic surfactant-polyelectrolyte-flocculant regulation strategy, providing guidance for optimizing flocculation and dewatering of CGFS.

In this work, a centrifugal drum with a double cone angle structure was proposed to enhance the supergravity separation of coal-series oil shale. The influence of feeding speed and motor frequency on the flow membrane formation in the centrifugal drums were studied by simulation. The average thickness of the flow membrane in different centrifugal drums was compared by experimental test. A supergravity separation system was constructed to investigate the effects of different operational factors on the separation efficiency of coal-series oil shale, and to compare the ash removal efficiency of coal-series oil shale with different cone angle structure separation systems. The results indicated that the flow membrane thickness in the double cone angle centrifugal drum was thicker than that in the single cone angle structure. For the double cone angle drum, the thickness of the flow membrane formed on the upper cone was obviously higher than that on the lower cone. Under the same conditions, the oil content of 0.5-0.25 mm, 0.25-0.125 mm and 0.125-0.074 mm coal-series oil shale concentrates increased by 1.31%, 1.79%, and 2.39%, respectively. This study provides a new approach for achieving ash removal and quality improvement of coal-series oil shale.

Conventional carbon recovery methods from coal gasification residues are plagued by inefficiency, high costs, and suboptimal environmental performance, necessitating the development of a novel approach that is both efficient and environmentally sustainable. Enrichment of residual carbon in coal gasification coarse slag was investigated using supergravity separation. The impact of operational parameters, specifically rotational speed and jet water pressure, on separation performance was evaluated using a novel multi-stage supergravity concentrator. The study delved into the synergistic mechanisms of centrifugal stratification and hydrodynamic erosion, analysing the microscopic properties of the separated products. Optimal separation conditions for various particle size fractions were identified, leading to high combustible recoveries. The kinetic erosion effect of the backwash jet was found to significantly enhance the separation process by effectively removing inorganic particles adhering to the residual carbon surface. Microscopic analysis confirmed that the surface of the separated concentrate exhibited improved cleanliness and smoothness relative to the original samples, indicating successful removal of inorganic impurities. Sequential separation by centrifugal force coordinated with backwash jets effectively solved the challenges posed by heterogeneous distribution and surface attachment during beneficiation, realizing efficient recovery of residual carbon in coal gasification coarse slag. Under optimal conditions, combustible recoveries of 93.89 %, 93.22 %, and 94.32 % were achieved for the 0.5 - 1 mm, 0.25 - 0.5 mm, and - 0.25 mm fractions, respectively. The study demonstrates the effectiveness of supergravity separation for residual carbon enrichment in coal gasification slag, offering an innovative solution for the improved application of supergravity separation and the recovery of coal-based solid waste resources.

Graphite is an important mineral resource, in this era of growing global demand for high-grade graphite, the advancement of its purification and separation technology is of great significance. This paper focused on the enhancement of ultraviolet (UV) modification on the enrichment and purification of graphite ores. Through charge-to-mass ratio sensing, SEM and FTIR, it was found that the superficial properties of the modified graphite particles were smoother and flatter, and the amount of O-containing functional groups connected with C was reduced, which strengthened the full contact between graphite particles and friction rods with the graphite's charging ability and improved the charge-to-mass ratio of graphite minerals. Accordingly, UV irradiation significantly improved the triboelectric separation performance, in which the separation efficiencies of graphite ores increased by up to 14.14 %. This work provided crucial information for resource purification and impurity elimination of graphite ores. (c) 2025 Published by Elsevier B.V. on behalf of The Society of Powder Technology Japan. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Brucite solid waste (BSW) is typically discarded during extraction process, leading to a significant resource waste and environmental pollution. This study developed a synergistic leaching-carbonation (SLC) system employing 2-hydroxybenzoic acid (2-HBA) and tetrasodium dicarboxymethyl aspartate (ASDA-Na4) for efficient Mg2+ extraction from BSW and subsequent synthesis of high-purity anhydrous MgCO3 (MC, MgO content: 47.20%). Optimal leaching conditions (0.6 M 2-HBA, 400 rpm, 353 K) yielded 96.87% Mg2+ leaching efficiency, which increased to 99.48% with ASDA-Na4 addition. Comprehensive analysis through leaching kinetics, DFT calculations and characterization techniques revealed that the formed O-H bond between 2-HBA and brucite weakened the O-Mg bond, promoting the release of Mg2+. Subsequently, the chelating effect of ASDA4- accelerated the leaching of Mg2+. During carbonation, thermally decomposed 2-HBA provided carbon sources while ASDA-Na4 acted as a crystal inducer. At 423 K for 8 h, increasing ASDA-Na4 addition from 3% to 15% induced a morphological transition of MC from flower-like spheres to rod-like structures. DFT calculations and characterization confirmed chemical adsorption of ASDA4- on MC crystals, directing crystal assembly and anisotropic growth. This study presents a novel approach and mechanistic analysis for the sustainable recycling of BSW, aiming to revolutionize the conventional utilization techniques.

Coal gasification slag (CGS) is considered as a potential fuel due to its high carbon content, but the high ash content limits its fuel application. Separation of carbon and ash fractions is the key to efficient utilization of CGS. However, the traditional carbon flotation process suffers from high dosages of collectors, low separation efficiency, and low recovery due to the enriched pore structure of carbon. The study recommended the use of kerosene-sodium oleate (NaOL) as a combined collector and calcite as a pore-plugging medium to improve the flotation recovery of carbon in CGS. Scanning electron microscopy (SEM) revealed that calcite, acting as a plugging medium, successfully entered and plugged the carbon pores. Flotation results indicated that the method could reduce reagent consumption by 75 % while achieving the same recovery. The contact angle test revealed that the kerosene-NaOL treatment increased the carbon-calcite contact angle from 57.75 degrees to 95.25 degrees, while the zeta potential shifted from 3.35 mV to -7.50 mV. In contrast, the contact angle and zeta potential of the ash were almost unchanged. This indicated that kerosene-NaOL was selectively adsorbed onto carbon-calcite. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) results further confirmed that kerosene-NaOL was adsorbed on the carbon surface though -COOH groups. Moreover, calcite could not only save reagents by plugging pores, but also enhance the NaOL adsorption by forming COOCa bonds with NaOL. Simultaneously, kerosene could also facilitate the adsorption of NaOL on the calcite surface, thus improving the overall flotation efficiency. Calculations based on the E-DLVO theory revealed that kerosene-NaOL treatment could significantly improve the adhesion between carbon-calcite and bubbles.

With the sharp increase in global demand for lithium resources, lepidolite has become an important source of lithium resources. However, the highly similar properties of lepidolite to feldspar make it difficult for traditional flotation collectors to achieve efficient and selective separation. Therefore, NaOL/PATC was adopted as the combined collector for lepidolite-feldspar separation. Flotation experiment showed that when pH = 9.0 and PATC : NaOL = 1:2 (concentration 6 x 10(-4) mol/L), a lepidolite concentrate with 83.47 % recovery, 4.35 % Li2O grade, and a separation efficiency of 73.69 % could be obtained, achieving efficient separation of lepidolite and feldspar. The study of flotation kinetics showed that the upward flotation process conformed to the first-order kinetic equation. The comparison of kinetic parameters showed that k and epsilon(infinity) of lepidolite were 14.43 times and 7.92 times those of feldspar, respectively, proving that this system could achieve rapid enrichment of lepidolite and effective removal of gangue minerals. The surface wettability results showed that after treatment with NaOL/PATC, the contact angle difference between lepidolite and feldspar expanded from 3 degrees to 16.08 degrees, indicating that NaOL/PATC could significantly increase the floatability difference. Zeta potential measurement indicated that NaOL/PATC could selectively adsorb on lepidolite, causing larger potential shifts than feldspar. FT-IR confirmed enhanced -CH3 groups from collectors on lepidolite after NaOL/PATC treatment, while XPS analysis further detected increased carbon content and corroborated the presence of -CH3 groups. In contrast, there was basically no change on feldspar, indicating that NaOL/PATC had the ability to selectively adsorb lepidolite.

Lithium is considered a critical metal element, with lepidolite being one of the sources of lithium. The similar floatability of lepidolite and feldspar complicates their flotation separation using a single collector. In this investigation, dodecylamine (DDA) and sodium hexadecanesulfonate (SHS) were utilized as a combined collector, and flotation tests and characterization analyses evaluated the collection performance of the DDA/SHS combined collector and revealed the adsorption mechanism. The flotation results showed that the DDA/SHS combined collector had excellent collection performance for lepidolite but was less effective for feldspar, and effectively separated lepidolite from feldspar. The zeta potential and contact angle results indicated that the DDA/SHS combined collector was co-adsorbed on the lepidolite surface but was difficult to be adsorbed on the feldspar surface, which expanded their difference in hydrophobicity. Surface tension results indicated that the solution properties of the DDA/SHS combined collector were superior to those of single DDA or SHS and exhibited a synergistic effect. The synergistic effect helped to change the adsorption difference of the DDA/SHS combined collector between lepidolite and feldspar. XPS and FT-IR analyses revealed that the adsorption amount of the DDA/SHS combined collector on lepidolite was significantly higher than on feldspar, amplifying their floatability difference. Consequently, the DDA/SHS combined collector could be considered an efficient flotation method for the purification of lepidolite.

The similar floatability of fluorapatite (FAp) and calcite (Cal) lead to difficulty in their separation using fatty acid collectors alone. To effectively recover FAp from Cal, a biodegradable polysaccharide, called Tamarindus indica kernel gum (TIKG), was introduced as an efficient Cal depressant in this study, and its depression mechanisms were elucidated. Flotation tests suggested that in sodium oleate (NaOl) system, TIKG strongly depressed Cal but hardly affected FAp, significantly widening the difference in their floatability. Infrared spectroscopy (IR), zeta potential, and wettability analyses indicated that TIKG had strong adsorption interaction with Cal, hindered NaOl adsorption on Cal, and significantly weakened the hydrophobicity of Cal, while the opposite effect was observed for FAp. X-ray photoelectron spectroscopy (XPS) proved that intense interactions of TIKG with Ca sites of Cal enhanced its adsorption on Cal rather than FAp. Extended Derjaguin–Landau–Verwey–Overbeek (EDLVO) calculations confirmed that TIKG reduced the hydrophobic attraction between Cal and bubbles and enhanced the electrostatic repulsion between them, thereby weakening Cal adhesion to bubbles and depressing Cal flotation. Consequently, TIKG achieved effective separation of FAp and Cal, in which 90.21% of Cal was efficiently removed in addition to 83.58% of FAp recovered. Based on these findings, TIKG serves as a Cal depressant for the purification of Cal-bearing phosphate ores by flotation.