Flotation Recovery Research Articles

Mechanism of pyrite depression by marine Fe(II)-oxidizing bacteria in seawater flotation

Seawater flotation is a promising technique to reduce environmental and economic loads in mineral processing. This study attempted to depress pyrite, a common gangue sulfide mineral, using two marine iron (Fe) oxidizing bacteria (MFeOB), Thalassospira sp. TF-1 and Mariprofundus sp. E-4, in seawater flotation without pH control; the MFeOB could contribute to hydrophilization of the pyrite surface by oxidation and/or adhesion of bacterial cells. Pyrite or chalcopyrite samples were preconditioned in seawater containing MFeOB for different times (15 min or 30 min). As a result of flotation experiments, the recovery of pyrite preconditioned without MFeOB (i.e., control sample) decreased to 64.2 % after 30 min reaction. The same recovery was observed when pyrite was preconditioned with Thalassospira sp. TF-1, whereas the recovery was successfully decreased to 20.2 % after preconditioning with Mariprofundus sp. E-4 for 30 min. X-ray photoelectron spectroscopy analysis of preconditioned pyrite samples showed no significant difference of Fe-oxidizing compounds between with and without MFeOB reaction, suggesting that the formation of hydrophilic substances such as Fe(OH)3 derived from pyrite oxidation by MFeOB is unlikely to be the main reason for the pyrite depression by Mariprofundus sp. E-4. The adhesion experiment revealed that MFeOB cells could cover the pyrite surface but not the chalcopyrite surface, showing that the hydrophilicity of Mariprofundus sp. E-4 cell caused the pyrite depression. This result suggests that the hydrophilic/hydrophobic properties of bacterial cells are a significant determining factor in pyrite recovery in seawater flotation in the case of MFeOB.

The influence of NaCl on xanthate adsorption on chalcopyrite surface and chalcopyrite flotation

Due to freshwater scarcity, mineral flotation plants have been using alternative water resources including seawater together with water recycling resulting in the accumulation of salts in process water. However, how salts affect the adsorption of xanthates on the surfaces of sulphide minerals and subsequent sulphide mineral flotation is unclear. To address the knowledge gap, this study investigated how NaCl affected the adsorption of potassium amyl xanthate (PAX) on chalcopyrite surface and chalcopyrite flotation. Cyclic voltammetry (CV) tests identified that NaCl increased the oxidation of PAX and its adsorption on chalcopyrite surface due to elevated ionic strength and electrical conductivity of water, facilitating charge transfer among PAX, chalcopyrite surface and oxygen. NaCl also increased chalcopyrite surface oxidation to produce more CuS, facilitating the formation of copper-xanthate complexes. Flotation tests identified that the increased adsorption of PAX by NaCl was only translated into improved true flotation of chalcopyrite at a low PAX concentration such as 50 ppm in NaCl solutions with low and medium concentrations (0.1 and 0.7 M, respectively). At a high PAX concentration such as 150 ppm, the coexistence of high concentrations of PAX and NaCl led to strong froth destabilisation, resulting in a dramatic reduction in water recovery and true flotation recovery of chalcopyrite. The findings from this study will be able to guide the flotation plants to maximise mineral flotation by choosing collector dosage based on the ionic strength of process water.

Pyrite activation in seawater flotation by copper and lead ions: XPS and in-situ electrochemical investigation

Pyrite, as the main carrier of gold, can be collected via flotation which consumes high volumes of fresh water. Seawater is the promising alternative to fresh water, especially in the fresh water deficient regions. However, pyrite flotation is usually ineffective in seawater, which requires activation prior to recovery. This study mainly focuses on the roles of Cu2+ and Pb2+ on pyrite flotation in seawater. The flotation and contact angle results indicated that Cu2+ and Pb2+ obviously increased pyrite recovery in seawater by enhancing its surface hydrophobicity. Further XPS studies revealed that the formation of Fe-S-Cu(I) and Fe-O-Cu(II) on pyrite surface due to Cu2+ activation while the presence of Fe-O-Pb(II) and Fe-SO-Pb(II) due to Pb2+ activation, thereby improving the active sites and adsorption of xanthate. In addition, the in-situ scanning electrochemical microscopy (SECM) results showed that the formation of Cu2+ and Pb2+ activated products increased the electrochemical reactivity of pyrite surface, which was the main reason for the improved pyrite floatability. Moreover, the current consequence evolution indicated that pyrite activation by Cu2+ was stronger than that by Pb2+. The SECM imaging also showed that the adsorption of xanthate decreased the electrochemical reactivity on pyrite surface, with more significant role observing on the activated surface than that of the un-activated pyrite. It should be noted that the Cu2+/Pb2+ activation and xanthate adsorption were distributed unevenly on pyrite surface. This study therefore provides an in-situ approach to understand the role of inorganic ions and reagents on pyrite flotation in seawater, providing a promising strategy to use seawater for the flotation recovery of gold.

Systematic investigation on bastnaesite flotation in the presence of dissolved calcium ions using organic acids as chelating agents

This study systematically investigated the potential of organic acids as Ca2+ ions chelating agents in bastnaesite flotation. Naturally, bastnaesite is associated with calcium-bearing gangue minerals, such as calcite (CaCO3) and fluorite (CaF2). The flotation beneficiation of bastnaesite in the presence of calcium-bearing minerals (e.g., calcite) is exceptionally complex due to the release of Ca2+ ions into the flotation pulp which changes the solution chemistry and bastnaesite surface properties. This study seeks to address the challenge of dissolved Ca2+ ions on bastnaesite flotation using organic acids, namely lactic, succinic, and citric acids. Systematic micro-flotation experiments were followed by electro-kinetic tests, solution chemistry studies, and XPS characterization. The results of this study showed that the elevated concentration of Ca2+ ions dramatically decreased bastnaesite flotation recovery values. However, organic acids formed soluble chelates with Ca2+ ions, effectively eliminating the detrimental impact of dissolved Ca2+ ions on bastnaesite flotation.

Amine-coated nanobubbles-assisted flotation of fine and coarse quartz

This study investigates the role of alkyl ether monoamine-coated nanobubbles (NBs) in assisting the flotation process of quartz across various particle sizes, on a bench scale. Experiments were conducted in a mini lab column utilizing a consortium of bubble sizes: D32 = 1200 μm for macrobubbles and D32 = 180–220 nm for amine-coated NBs. The study revealed that an increase in amine-coated NBs correlates well with a decrease in the air/solution’s interfacial tension caused by the ether amine at less than 68 mN m−1. True flotation recoveries with varying amine/g quartz, where the collector-frother amine may be amine-coated NBs alone or assisted by NBs generated in pure water, were compared with blank tests, in the absence of NBs. The flotation study evaluated size-to-size fractions from fine (−20 µm) to coarse (up to 150 µm) particles and their mixtures. In addition, the work extended to explore the behavior of the “super” coarse quartz from 150 µm up to 1000 µm. The results highlighted a clear dependence on the particle size, with NBs improving recoveries in all fractions, especially the difficult-to-treat ultrafine/fine and coarse quartz. Recovery results exceeded 90 % in all fractions (isolated or in mixtures) at a high rate with the amine-coated NBs. The mechanisms proposed improved flotation performance attributed to the high numerical concentrations of NBs (at least 2–3 × 1010 NBs per gram of quartz) rapidly attaching to quartz surfaces, serving as “seeds” for the adhesion of larger bubbles generated in conventional flotation cells. This interaction facilitates the formation of lightweight, cluster-like aggregates that swiftly rise to the column’s surface. Notably, larger quartz particles (+355 µm) form the bigger hydrophobic and buoyant clusters, leading to their rapid levitation and effective phase separation, with over 95 % separation efficiency. This innovative technique’s significance, outcomes, and potential scalability are thoroughly discussed, highlighting its promising applicability in diverse mineral and ore flotation systems, particularly those containing quartz and silicates.

Enhanced marmatite activation by copper with ammonium sulfate: An experimental and DFT investigation

The presence of iron atoms on the marmatite surface hinders effective interaction between the activator and the mineral, leading to unsatisfactory flotation performance through direct copper (Cu) activation. Hence, this study introduced ammonium sulfate to enhance the marmatite-activation capability by Cu ions. Additionally, the reinforcement mechanism was investigated through microflotation tests, atomic force microscopy (AFM), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and density-functional theory (DFT) calculations. Microflotation results demonstrated that the addition of ammonium sulfate as a complexing reagent increased the flotation recovery of marmatite by 17.36%. AFM analysis revealed that marmatite subjected to enhanced activation (i.e., in the presence of ammonium sulfate) exhibited a considerably higher surface roughness than that subjected to direct Cu activation. Moreover, the average height of hill-shaped materials on the marmatite surface notably increased to 9.6 nm after enhanced Cu activation. SEM-EDS analysis revealed that the concentration of Cu atoms (2.2%) on the marmatite surface after enhanced Cu activation was nearly three times that (0.8%) after direct Cu activation. Additionally, XPS results indicated a considerably higher presence of the Cu–S component on the marmatite surface after enhanced Cu activation than after direct Cu activation. ToF-SIMS analysis indicated an increase in the fragment peaks of Cu+, CuOCS2+, OCS2−, and OC2H2S2− on the surface of enhanced-activated marmatite. Additionally, DFT calculations indicated that the presence of NH3 molecules enhanced electron transfer between Cu and S on the hydrated marmatite surface. The marmatite (1 1 0) surface exhibited more negative adsorption energy of Cu ions after the action of NH3 molecules, and NH3–Cu showed a more stable adsorption configuration than Cu. Therefore, the addition of ammonium sulfate enhanced the Cu activation for marmatite, thereby improving flotation performance.

Investigation of the flotation behavior and interaction characteristics of micro-fine quartz and magnesite in a dodecylamine system under ultrasonic treatment

Ultrasonic treatment, as an important surface modification method, profoundly affects the flotation behavior of minerals. This study examined the impact of ultrasonic treatment on the surface properties and flotation performance of magnesite and quartz in a dodecylamine (DDA) flotation system. Atomic force microscope detection results revealed that the surface roughness and roughness size of both magnesite and quartz increased after ultrasonic treatment. Flotation tests indicated that the recovery rates of magnesite and quartz were lower after ultrasonic treatment. At pH of 10 and DDA of 75 mg/L, ultrasonic treatment led to a 0.66%, 3.46%, and 0.33% decrease in the flotation recovery rates for three different magnesite particle sizes. Following ultrasonic processing, the flotation recovery rates for three different quartz particle sizes decreased by 8.48%, 30.76%, and 43.69%, in that order. X-ray photoelectron spectroscopy detection results showed an increased presence of characteristic Mg and Si sites on the surfaces of magnesite and quartz following ultrasonic treatment. DDA acted on the surfaces of the two minerals through electrostatic adsorption and hydrogen bonding adsorption and repelled the flotation of minerals owing to the same charge as characteristic sites, thereby reducing flotation recovery. Adsorption capacity tests and contact angle measurements demonstrated a decrease in DDA adsorption and contact angle on the surfaces of magnesite and quartz after ultrasonic treatment, explaining the reduced floatability. Extended Derjaguin–Landau–Verwey–Overbeek theoretical calculations indicated that before ultrasonic treatment, there was a repulsive energy between magnesite and fine-grained quartz particles. After ultrasonic treatment, the interaction energy between magnesite and fine quartz particles is mutual attraction.

Open-Circuit Technology of Zinc Oxide Ore Flotation with Ternary Collector and Its Adsorption Characteristics on Smithsonite Surface

The sulfidization-amine flotation method is commonly used for the beneficiation of zinc oxide ores. Lanping zinc oxide ores contains 8.40% zinc, with the main mineral being smithsonite; additionally, they have a high mud content. Conventional sulfidization–ammonium flotation presents a low flotation index and unsatisfactory flotation froth. A new open-circuit technology is employed to treat Lanping zinc oxide ores, where Na2S, KG-248, and dodecyl amine + sodium isoamyl xanthate + ammonium dibutyl dithiophosphate are used as the regulator, depressant, and ternary collector, respectively. Consequently, the flotation indices for the zinc grade and recovery are 28.71% and 86.24%, respectively, and the flotation froth becomes more stable. Subsequently, the flotation behavior and adsorption mechanism of smithsonite with a ternary collector are investigated. The flotation recovery of smithsonite increases to 94.40% after treatment with the ternary collector. Surface-analysis results indicate that the ternary collector can synergistically adsorb onto the sulfidized smithsonite surface to enhance its hydrophobicity, thus increasing the floatability of smithsonite. Meanwhile, the total consumption of the collector in the ternary-collector system is lower than that in the binary- or unitary-collector system.

An investigation into the effect of Eh and pH on the adsorption of a xanthate collector on sperrylite (PtAs₂): A surface and solution characterization study

There is evidence of a very weak interaction between sperrylite and xanthate collectors at pH 9, the typical pH used in PGM concentrators. This results in the mineral being hardly hydrophobic when exposed to such collectors. Xanthate collectors adsorb via an electrochemical mechanism which is dependent on pH and Eh. In this study, it was shown that potassium amyl xanthate (PAX) adsorption increases with decreasing pH, with 2.9x10−05 mol/m2 adsorbed at pH 3 compared to only 0.4x10−05 mol/m2 at pH 9. Furthermore, spectroscopic analyses performed in this study showed that PAX is adsorbed as dixanthogen at pH 3 whereas this species was not observed at pH 9. In addition to dixanthogen, the collector may be co-adsorbed as the metal xanthate on sperrylite. However, it is the specific presence of dixanthogen that ultimately strongly promotes the hydrophobicity of the mineral. The adsorption of the collector on sperrylite correlated well with the flotation recovery of this mineral. The microflotation recovery of sperrylite was improved from 22 % at pH 9 to 61 % at pH 3. On the other hand, the use of NaClO to chemically modify Eh was shown to result in excessive oxidation of sperrylite and/or resulted in a reaction between NaClO and PAX which in fact hindered the ability of the collector to impart hydrophobicity. This was found to have a detrimental effect on the floatability of sperrylite. Ultimately, this study provides evidence and insights into the floatability of sperrylite.

Sulfidation of Smithsonite via Microwave Roasting under Low-Temperature Conditions

This study employs microwave roasting to decompose smithsonite mineral (zinc carbonate) into zinc oxide, which then reacts with pyrite to sulfurize its surface, forming zinc sulfide. This process is beneficial for the flotation recovery of zinc oxide minerals. The surface sulfidation behavior of smithsonite under low-temperature microwave roasting conditions is examined through X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and thermodynamic calculations. XRD and thermodynamic analysis indicate that smithsonite completely decomposes into zinc oxide at 400 °C. Introducing a small amount of pyrite as a sulfidizing reagent leads to the formation of sulfides on the surface of decomposed smithsonite. XPS analysis confirms that the sulfide formed on the surface is zinc sulfide. SEM analysis reveals that sulfides are distributed on the surface of smithsonite, and the average sulfur concentration increases with the pyrite dosage. Microwave-assisted sulfurization of smithsonite (ZnCO3) was found to significantly enhance its floatability compared to conventional sulfurization methods. The optimal mass ratio of ZnCO3 to FeS2 is approximately 1:1.5, with the best temperature being 400 °C. These findings provide a technical solution for the application of microwave roasting in the efficient recovery of smithsonite through flotation.

Study on the selective separation mechanism of tannin acid in chalcopyrite and talc: Insights from adsorption morphology and electrochemical analysis

A key strategy for achieving the selective separation of talc and chalcopyrite is the development of chemical depressants with high solubility and strong selectivity. Tannic acid (TA), a polyphenol found in green plants and has good solubility, contains abundant phenolic hydroxyl groups. Moreover, the adsorption mechanism of TA with chalcopyrite and talc was examined after TA was chosen as the separation depressant for chalcopyrite and talc. Single-mineral flotation test results found that at optimal pH and TA and sodium butyl xanthate (SBX) dosages, the flotation recoveries of talc and chalcopyrite were 9% and 92.17%, respectively, and the difference in recovery between them was 83.17%. Results from real ores and artificially mixed minerals tests also confirmed that TA can achieve selective separation of chalcopyrite and talc. Since chalcopyrite has distinct electrochemical properties, the results of atomic force microscope and electrochemical tests demonstrated that there are significant differences in the adsorption behavior of TA on the surface of chalcopyrite and talc. And the adsorption selectivity of SBX on the chalcopyrite surface is better than that of TA on the chalcopyrite surface, which is an important reason for the selective separation of chalcopyrite and talc.

Sodium dodecyl benzene sulfonate as a new ligand to enhance the flotation of cassiterite in Pb-BHA system

As high-quality cassiterite resources dwindle, the significance of cassiterite associated with scheelite escalates. In this study, we synthesized a novel lead-group double ligand collector (Pb-BHA-SDBS) by introducing a new ligand, sodium dodecyl benzene sulfonate (SDBS), into the structure of lead complexes of benzohydroxamic acid (Pb-BHA). The flotation performance of Pb-BHA-SDBS was investigated by single-mineral flotation. The structural and chemical properties of Pb-BHA-SDBS were systematically investigated through FTIR, XPS, and quantum chemical calculations. The mechanism of enhancing cassiterite flotation with Pb-BHA-SDBS were investigated through adsorption energy analysis, XPS, AFM and contact angle analysis. The flotation recovery of cassiterite greatly increased from ≤30 % to ≥80 % when the Pb-BHA-SDBS is utilized as the collector. The FTIR and XPS results indicated that both SDBS and BHA form coordination bonds with lead ions, significantly strengthening the adsorption ability on the cassiterite surface. The adsorption of Pb-BHA-SDBS on the surface of cassiterite forms larger colloidal aggregates, further enhancing the roughness and hydrophobicity of the cassiterite surface, thereby strengthening the flotation of cassiterite.

A rheological study on nano-bubble assisted flotation of phosphate fine particles

ABSTRACT The application of ultrafine bubbles a.k.a. nano-bubbles (NBs) in upgrading the flotation recovery of fine particles has been extensively investigated from various perspectives over the last two decades. However, their rheological aspect has not been studied yet, which is presented for the first time in this paper. To this end, the current study addresses the effect of six crucial variables including solid content (5%, 15%, and 25% (w/w)), presence and absence of NBs, inner diameter of a Venturi tube (1.5 and 2.2 mm), pH of pulp (4.5–11) and frother dosage (3, 13, and 33 mg/L) on the variation of rheological parameters i.e. shear stress, shear tension, and viscosity. Ultrafine bubbles were generated in a conditioning tank through the hydrodynamic cavitation mechanism using a fatty-acid-based frother (Flo-Y-S), while the rheological responses were continuously monitored and measured by a rheometer and parallel plate spindle (for pulp) and a double gap spindle (for NBs). Flotation tests were conducted on a high-grade phosphate ore (d80 = 37 µm) using a mechanically agitated Denver®-type (D12) flotation cell. The experimental results revealed that fluid behavior without NBs using 13 mg/L frother was in the range of shear rates less than 1 s−1 non-Newtonian and close to the shear thinning state, while it became completely Newtonian in the range of 1 to 1500 s−1. However, the presence of NBs at the same frother content changed this tendency to non-Newtonian and Newtonian fluids at shear rates of <30 s−1 and >30 s−1, respectively. It was also found that either in acidic (5.5) or strong alkaline (11) domains, the pulp viscosity trends were almost close to each other and varied from 0.002−10 to 0.002−4 Pa.s, respectively. On the other hand, on the same trend, the amount was lowered to three times in the neutral range (7.5) and weak alkalinities (9). Diminishing the inner diameter of the Venturi tube from 2.2 mm to 1.5 mm led to an increment of shear stress and viscosity about twice at the shear rates <100 s−1. The results of evaluating frother dosage showed that an increase in the amount of frother dosage, which reduced bubble dimensions, exceeded the viscosity and the amount of shear stress. Finally, we concluded that the rheological properties significantly impacted the selective separation of NB-assisted flotation processes and need further investigations in the future.

COMPARATIVE ANALYSIS OF FLOTATION EFFICIENCIES BETWEEN MICROFLOTATION CELL AND BATCH FLOTATION CELL TESTS

One of the most important methods in the beneficiation of sulfide ores is flotation. Flotation experiments on a laboratory scale are mainly carried out through batch flotation and microflotation tests. In this study, comparative flotation experiments of pyrite minerals were conducted under the same conditions using the two methods mentioned above. A series of experiments were carried out with different pH values and collector dosages selected as flotation parameters. The highest flotation recovery was obtained at a pH of 7.5 with the use of PAX. Furthermore, within the conditions studied, a correlation of 94% was found between the two flotation techniques when using PAX, while it was 98% in the use of PEX. In this study. It was shown that the microflotation method can be used to estimate the efficiency values that can be obtained with batch flotation experiments.

A novel combined collector for high-performance flotation of cassiterite: Experimental insights and MD simulations

Collectors are critical in the flotation and separation of fine-grained minerals. In this study, a new combined collector, namely phosphoric acid (SPA)/dodecylbenzene sulfonate isopropanolamine (DBIA) was prepared via self-assembly. First, the flotation of cassiterite was investigated using SPA and DBIA separately, and the micro-collection mechanism of these single-material collectors on the surface of cassiterite was clarified by density functional theory calculations. Then, combined SPA/DBIA collectors were prepared, and the effect of the SPA/DBIA molar mass ratio on cassiterite flotation performance was studied. Surface tension measurements and molecular dynamics (MD) simulations were used to investigate the gas–liquid interfacial self-assembly of the SPA/DBIA collector. Subsequently, the flotation separation behavior of SPA/DBIA on the solid–liquid–gas interface was experimentally evaluated, and the adsorption mechanism of this combined collector at the three-phase interface was comprehensively investigated by performing MD simulations. The results show that SPA/DBIA combined collectors can obtain 80.88 % cassiterite flotation recovery at 1.2 × 10−4 mol/L. The addition of SPA led to the continuous adsorption of DBIA on the surface of cassiterite, forming a more stable and dense adsorption film. The mass density of the adsorption film was 319.27 ng/cm2, owing to the synergistic co-adsorption. Finally, the surface of the cassiterite was modified to enhance its hydrophobicity. This work demonstrates the application of collector self-assembly to improve the recovery of fine-grained cassiterite via flotation.

Exploring the impact of thiol collectors system on copper sulfide flotation through machine learning-driven modeling

Collector selection is a critical step in flotation, as it has a direct impact on product quality, flotation recovery, and selectivity. Collectors can consist of different components, and their effectiveness can vary depending on the type of ore being processed. The general practice in both literature and in industry is to use a mixture of collectors rather than a single collector. However, the use of a collector mixture introduces several complex issues. It is challenging to determine the specific effects of each collector on different minerals, as well as to understand the synergistic effects of mixed collectors in flotation. This study presents a novel investigation focusing on the impact of blends of NAX, AEROPHINE® 3422, and AERO® MX 5149, in varying dosages and combinations, on the flotation performance of Kupferschiefer copper ore. Kinetics flotation tests were conducted using a mechanical flotation cell with various combinations and dosages of listed collectors. For this investigation, different predictive models such as machine-learning (ML) and conventional regression analyses were developed. For model construction, a database including the results of comprehensive experimental results was constructed. The best performing model was selected considering statistical performance indicators and their performance on unseen data. A sensitivity analysis was conducted on the model to justify contributions of collectors on the copper recovery and grade. The results showed that the ML-based models provide compatible results with the expert opinions and have higher statistical performance than conventional modelling tools. According to the experimental results and models’ findings, it has shown that AEROPHINE® 3422 (a blend of isopropyl ethyl thionocarbamate and dithiophosphinate) was the most influential collector for the copper recovery. In addition, two ternary graphs were generated from the modeled data to formulate mixtures for different grades and recovery priorities.

Impact of power input in pulp conditioning on coal flotation and real-time characterization by focused beam reflectance measurement (FBRM)

ABSTRACT Pulp conditioning is a necessary procedure in the coal flotation industry, and optimizing the power input of such processes is in favor of improving flotation efficiency and reducing costs. This paper applied a pulp conditioning system combined with the focused beam reflectance measurement (FBRM) to investigate the impact of power input on coal flotation. Under the same energy input, the highest flotation efficiency of 50.09% was achieved in a pulp conditioning pattern of 1800 rpm-3 min, but the flotation efficiency reached only 36.13% in 1200 rpm-7.2 min. The kerosene collector can disperse into large numbers of droplets that exceed 2000 counts/s at size fractions of −10 μm and 20–50 μm in high power input and achieve better adsorption on coal. In the pulp conditioning process, the coal particle numbers of −50 μm size fraction decreased significantly from 15,000 counts/s to nearly 8000 counts/s at 32.3 W power input and coarse aggregates of 50–1000 μm size were detected. Under high power input conditions caused by high agitation speed, extra energy contributed validly to the kinetic energy of coal particles/collector droplets and the generation of oil-water and oil–coal interfaces. The shear flocculation behavior induced by the high power inputs in pulp conditioning is favorable for the flotation recovery of fine and ultra-fine particles.

A novel 3-tetradecylamine propyl amidoxime collector for highly efficient flotation of fine kaolinite

How to flotation fine kaolinite efficiently is a challenge. For the improvement of fine kaolinite flotation recovery, a novel 3-tetradecylamine propyl amidoxime (TPA) collector was synthesized. In comparison to the conventional collector tetradecylamine (TDA), the fine kaolinite exhibited better floatability in the TPA system, with a recovery of 90.5% in micro-flotation experiments. It was indicated by contact angle tests that TPA was more effective in improving the hydrophobicity of kaolinite by increasing its contact angle from 24.5° to 85°. Fourier transform infrared spectroscopy (FTIR) indicated that the adsorption of TPA on kaolinite surface was by electrostatic interaction, and zeta potential tests showed a significant increase in the surface potential. In addition, it was learned that TPA interacts with the kaolinite surface more effectively than TDA by using density functional theory (DFT) calculation. Therefore, TPA with excellent performance is expected to be a novel and efficient fine kaolinite flotation collector.

Efficient sulfidization-free flotation of chrysocolla enabled by specific synergistic effects of ammonium sulfate and octyl hydroxamic acid

Due to its poor sulfidization effect and environmental issues, the traditional sulfidization–xanthate method faces challenges in chrysocolla flotation. Addressing these, our study pioneers a sulfidization-free approach using ammonium sulfate as an activator in an octyl hydroxamic acid (OHA) collector system. This innovation propels flotation recovery from 34.10 % to an impressive 98.43 %. Infrared spectroscopy and adsorption tests confirm that ammonium sulfate improves OHA’s adsorption on chrysocolla. X-ray photoelectron spectroscopy (XPS) analysis reveals a significant rise in C–C and C-N bonds related to OHA on the mineral surface post-activation. Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS) analysis shows a rougher mineral surface with filamentous precipitates and a higher surface nitrogen atom concentration. Density Functional Theory (DFT) calculations elucidate NH3′s role in disrupting the hydration layer, exposing more Cu sites for enhanced OHA attachment. The Cu 2p shift observed on the mineral surface, along with state density analysis, further confirms the chemical adsorption of OHA on chrysocolla’s Cu sites facilitated by ammonium sulfate. This study introduces a novel NH3-enhanced OHA adsorption method, offering a promising strategy for the efficient flotation of chrysocolla.

Enhancing Sulfidization and Flotation of Smithsonite Using Eco-Friendly Triethanolamine: Insights from Experimental and Simulation Studies.

Triethanolamine (TEA) is a promising eco-friendly alternative to inorganic ammonia for enhancing surface sulfidization and flotation recovery of smithsonite. Micro-flotation experiments revealed an enhancement in smithsonite recovery to 95.21% with TEA modification, comparable to the results obtained using ammonia. The mechanisms behind the ability of TEA to enhance the sulfidization process were investigated through surface analysis and molecular dynamics simulations. TEA modification increased the content of sulfidization products, the proportion of crucial S22- in adsorbed products, and the thickness and size of the sulfidization product layer. The complexation of TEA with Zn sites formed positively charged Zn-TEA complexes that adsorb onto the smithsonite surface. These complexes promoted negatively charged HS- adsorption, creating a multi-layered adsorption structure. Moreover, TEA modification reduced the total energy required for the sulfidization. These findings open up new possibilities for using eco-friendly reagents in mineral processing, highlighting the potential of TEA in green mineral processing practices.