Flotation Of Hematite Research Articles

Study on Dynamic Behavior and Mechanism of Reverse Flotation of Micro-fine Hematite (MFH) Enhanced by Nanobubbles (NBs)

Study on Dynamic Behavior and Mechanism of Reverse Flotation of Micro-fine Hematite (MFH) Enhanced by Nanobubbles (NBs)

Enhancement mechanism study on the fine hematite flotation by hydrophobic glass microspheres

Previous studies have primarily focused on the use of coarse mineral particles or hydrophobic materials as carriers, whereas this study was the first to investigate the impact of different hydrophobic glass microspheres (HGM-butane, HGM-pentane and HGM-octane) on the flotation behavior of fine hematite, and it revealed the interaction mechanism through Zeta potential and flotation kinetics analysis. The results of micro-flotation tests indicated that the addition of HGM-pentane can increase the flotation recovery of fine hematite from 65.27 % to 84.64 %, which was significantly better than using the collector NaOL alone. Zeta potential results showed that the incorporation of HGM-pentane caused a further negative shift in the surface potential of hematite, enhancing its adsorption capacity with bubbles. Flotation kinetics analysis demonstrated that the addition of HGM-pentane increased the flotation kinetic constant, promoting the flotation rate of fine hematite. This study revealed that the interaction between hydrophobic glass microspheres and fine hematite was primarily through hydrophobic forces and electrostatic attraction, forming a hematite-HGM complex, which in turn improved the flotation recovery of fine hematite. This provided a theoretical basis for the development of efficient flotation reagents and offers new insights into the efficient utilization of fine hematite.

Mechanism of sodium lauryl sulfate reducing froth stability of dodecylamine in hematite flotation: Experiments and molecular dynamics simulation

In this study, the influence of sodium lauryl sulfate (SLS) on the stability of dodecylamine (DDA) froth during the reverse flotation of hematite was investigated due to the frequent issue of excessively viscous foam leading to suboptimal reverse flotation outcomes. The research involved conducting flotation tests and two/three-phase froth stability assessments to explore how a specific molar ratio combination of DDA and SLS could enhance the flotation performance while simultaneously mitigating froth stability. The investigation into the mechanism by which SLS reduces the stability of DDA froth was aided by molecular dynamics simulations. The findings revealed that in the collector system comprising DDA and SLS, several key changes occurred at the molecular level. These included a decrease in the thickness of the electric double layer at the interface, a reduction in the thickness of the gas–liquid interface layer, weakening of the interaction strength between the head group and water molecules, a decrease in the coordination numbers of water molecules in the first hydration layer, and an enhanced migration ability of water molecules. Furthermore, there was an increased inclination angle between the head groups or molecular chains of the collector and the Z-axis, resulting in a diminished interaction depth between the head group and water and a closer positioning of the molecular tail chain to the gas–liquid interface with a more pronounced curvature. Consequently, these molecular adjustments led to a sparser arrangement of DDA molecules at the gas–liquid interface, lower coverage of the interface adsorption layer, and increased gas permeation, ultimately reducing DDA froth stability. The aforementioned conclusions provide a comprehensive molecular-level analysis of the principal mechanisms that can effectively reduce foam stability, including the attenuation of molecular head group-water interactions, reduction in gas–liquid interface layer thickness, decrease in gas–liquid interface orderliness, and enhancement of water molecule migration capability. The implications of this research extend to providing theoretical insights for addressing foam control challenges in DDA flotation processes.

The influence of hydrochloric acid corrosion pretreatment on the flotation performance of hematite and its surface acid corrosion mechanism

This study systematically investigated the impact of Hydrochloric acid (HCl) corrosion pretreatment on hematite flotation within the NaOL system, analyzing the influence of varying HCl concentrations (measured as pH) on hematite acid corrosion. The results showed that at pH = 1, after 4 min of acid corrosion, hematite exhibited optimal floatability, achieving a recovery rate of 82.49 %, significantly surpassing the original ore. Conversely, at pH = 5, after the same duration of acid corrosion, hematite’s flotation is inhibited, yielding a recovery rate of 59.38 %, lower than the original ore. Through contact angle, adsorption amount measurements, and AFM detection, it is observed that after corrosion in pH = 1 HCl solution, hematite surface roughness increases, more NaOL collector is adsorbed, leading to significant hydrophobicity enhancement. After corrosion in pH 5 weak acid environment, despite increased surface roughness, hematite surface was coated with particulate matter, greatly reducing NaOL adsorption and further decreasing hydrophobicity. Further analysis using FTIR, XPS, and hydrolysis component calculation indicated that after acid corrosion in HCl at pH = 1, hematite exposed more active Fe sites, enhancing flotation performance. Conversely, at pH = 5, surface-dissolved Fe3+ transformed into hydrophilic Fe(OH)3, inhibiting flotation by covering the hematite surface.

Effect of bubble properties and dispersion characteristics in microbubble counter-current collision flotation column

ABSTRACT Cationic collectors are widely used in the flotation of hematite, silicate, oxides, etc. GE-601, as a new type of cationic collector, which was used in various mineral flotation process, has achieved excellent selection indexes. In order to study foaming performance of GE-601, the bubble characteristics are studied in an experimental scale two-phase flotation column. A high-speed camera recorder is used to take bubbles’ images and the distribution of bubble diameter under different conditions is measured by image analysis. Moreover, the surface tension of bubbles under different reagent concentrations is measured by a surface tension meter. Studies show that as GE-601 concentration increases, d 32 gradually decreases and after exceeding CCC, Sauter mean diameter (d 32) stabilizes at 0.562 mm. When the bubble diameter decay degree is 99%, 90% and 50%, GE-601 concentration reaches 0.112 mol/m3, 0.0643 mol/m3, and 0.0295 mol/m3, respectively. The adsorption concentration of GE-601 is about 0.0254 μmol·m−2. GE-601 reduces pulsation on the surface of bubbles in flowing liquid. During the rise of bubbles, d 32 is approximately linearly related to measured height, but the concentration of d 32 and GE-601 decrease varies linearly.

Application and Mechanism of Mixed Anionic/Cationic Collectors on Reverse Flotation of Hematite

Application and Mechanism of Mixed Anionic/Cationic Collectors on Reverse Flotation of Hematite

Selective separation of hematite and chlorite by eco-friendly inhibitor syringic acid and its mechanism

In this work, using syringic acid (SA) as a novel eco-friendly inhibitor and dodecylamine (DDA) as a collector in a cationic reverse flotation system, the effect of SA on the flotation separation of hematite and chlorite was investigated. Micro-flotation experiments and artificial mixed mineral experiments were conducted to study the flotation behavior of hematite and chlorite in the presence of SA. The adsorption mechanism of SA on the surfaces of hematite and chlorite was analyzed through methods such as Zeta potential, AFM, FTIR, XPS testing, and DFT calculations. Flotation experiments showed that after adding SA, the recovery rate of hematite was 88.87%, and that of chlorite was 7.01%, effectively achieving the separation of hematite and chlorite. Mechanism analysis indicated that SA could form complexes with Fe atoms, selectively adsorb on the surface of hematite, hinder the adsorption and capture of DDA on hematite, and suppress the flotation of hematite without affecting the surface properties of chlorite. Therefore, SA can serve as apotential selective inhibitor for the separation of hematite and chlorite.

Application and mechanism of an efficient hydrophobic flocculant CPAM in the flocculation reverse flotation of hematite and microfine-grained chlorite

Chlorite is often associated with hematite and tends to form microfine particles during grinding, making it challenging to recover and separate from hematite through flotation. This study innovatively applies an ester-based cationic polyacrylamide (CPAM) as a flocculant in a reverse flotation system using dodecylamine (DDA) as a collector, to flocculate and recover microfine-grained chlorite. The method achieves efficient separation between microfine chlorite and hematite. Laser particle size testing and optical microscopy show that CPAM significantly increases the apparent particle size of microfine chlorite, causing it to aggregate into flocs, while having a extremely weak effect on hematite flocculation. Further analysis using techniques like Zeta potential, contact angle measurement, Fourier-transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) reveals CPAM's stronger adsorption affinity for chlorite compared to hematite. The ester groups in CPAM selectively form hydrogen bonds with chlorite's surface H atoms, enhancing its hydrophobicity. Particle-bubble attachment angle testing confirms that the flocculated chlorite flocs exhibit better floatability and higher efficiency in collision and adhesion with bubbles. Thus, CPAM serves as an efficient flocculant for reverse flotation separation of microfine chlorite and hematite.

Effect of Sodium Hexametaphosphate on Flotation of Quartz and Hematite with Starch/Etheramine in the Presence of Ca and Mg Ions

ABSTRACT The aim of this study was to evaluate the effect of sodium hexametaphosphate (SHMP), a complexing reagent for Ca and Mg ions, on iron ore reverse cationic flotation. Quartz and hematite samples contaminated with both Ca and Mg were subjected to microflotation assays at pH 10.5 with starch and etheramine, which showed that SHMP did not provide selectivity in the separation of these minerals. Zeta potential measurements, Fourier transform infrared spectroscopy of quartz and hematite without and with the studied reagents (starch, amine, SHMP, CaCl2/MgCl2) and published studies in the literature indicated that although the HMP anions removed the Ca and Mg ions from both minerals, it also formed complexes with the Fe3+ ions on the hematite surface, which prevented subsequent adsorption of starch and consequently decreased the selectivity for reverse flotation of iron ore.

Effects of agitation intensity and foam stability on the Floc-flotation of ultrafine minerals using a laboratory flotation column

In the present study flocculation flotation (floc-flotation) of ultrafine hematite and quartz was investigated in a laboratory-scale flotation column. A direct flotation scheme was used to float hematite using in-house synthesized n-octyl hydroxamic acid (OHA) as a collector. A polymer system containing tannic acid (TAN) and poly(ethylene oxide) (PEO) was used to flocculate quartz to reduce its entrainment. The effects of agitation intensity and foam stability on floc size distribution, entrainment reduction, and flotation kinetics/recovery were investigated. It was shown that the dual polymers TAN-PEO were effective in reducing quartz entrainment, and that the degree of entrainment reduction was affected by the intensity of agitation. A correlation was established between the mean floc size and a reduction in quartz entrainment. TAN-PEO dual polymer system also enhanced the flotation kinetics and recovery of hematite by OHA, originating from a synergistic effect between PEO and OHA. Therefore, higher separation efficiency was achieved from synthetic ultrafine hematite and quartz mixtures when TAN-PEO was added after OHA. The underlying mechanisms were studied by floc size distribution, surface tension, and foam height and decay time measurement. This work helps understand the relationship between hydrodynamic condition, flocs size, and mechanical entrainment when polymeric flocculation is used for entrainment reduction in fine and ultrafine minerals flotation.

Properties and potential application of ozone-oxidized starch for enhanced reverse flotation of fine hematite

In this study, ozone as an eco-friendly oxidant was employed to improve the depressive performance of starch in the reverse flotation of fine hematite. Micro-flotation results showed that ozone-oxidized starch (OS) better depressed hematite flotation as compared to the native starch (NS). Particle surface wettability and size distribution analysis suggested that OS rendered the hematite surface more hydrophilic in the presence of an amine collector while maintaining a comparable flocculation performance to that of NS. Solubility, rheology, carbonyl and carboxyl content measurements, together with atomic force microscopy (AFM) imaging were performed to examine the variations in the structure and properties of starch upon ozonation and their correlation with the depressive performance of starch. It was found that ozone treatment not only increased starch acidity and solubility, but also concurrently depolymerized starch with the yield of low molecular weight derivatives. These favorable changes appeared to be responsible for the superior performance of OS. Furthermore, the stronger interaction of OS with hematite was verified by X-ray photoelectron spectroscopy (XPS).

Investigation into starch adsorption on hematite and quartz in flotation: Role of starch molecular structure

Various starches have been used as depressants in reverse flotation of iron ores. To date, the effect of molecular structures of starches on the depressing behavior is still not clear using simulation study. In this study, three starches with different ratios of amylose/amylopectin on the molecule (Normal Starch, Waxy Starch and Gelose 50) were used to study their depressing ability on the flotation of hematite and quartz. Microflotation, Zeta potential measurement, XPS analysis and AFM measurement were performed to investigate the interaction between the two minerals and the three starches. It was found that chemisorption occurred between hematite and the starches, while only hydrogen bonding was observed between quartz and the starches. In addition, it was obtained that the chemisorption strength between the starches and hematite under alkaline condition fell in the order: Waxy Starch > Normal Starch > Gelose 50, which was closely related to the ratios of amylose/amylopectin. The underlying mechanism for the different chemisorption strength was revealed via computational chemistry analysis. It is believed that the outcomes of this work could optimize the development of starch-based depressants in iron ore flotation.

Three-phase froth stability in hematite flotation using DDA as a collector

The effect of hematite and quartz with different particle sizes on the three-phase froth stability using dodecylamine (DDA) as a collector was investigated, and the mechanism of how quartz improves froth stability was explored. Microflotation experiment, three-phase froth stability experiment, froth morphology photography, pulp viscosity measurement, contact angle measurement, zeta potential measurement, time-of-flight secondary ion mass spectrometry analysis, and molecular dynamics simulation were conducted in this investigation. Results showed that flotation performance and froth stability were obviously different for minerals with different particle sizes. The froth half-life was remarkably higher in the presence of quartz particles compared with hematite particles, forming stickier froth, especially for quartz particle sizes below −18 μm. Fine quartz was found to be a key factor in improving the froth stability in hematite flotation using DDA as a collector. The high pulp viscosity, damping coefficient, and maximum capillary pressure resulting from quartz with low density, small size, and high concentration hindered liquid drainage and reduced the desorption probability of particles from the bubble surface, thereby preventing the coalescence of two adjacent bubbles. DDA was found to be more readily adsorbed on the quartz surface, leading to a higher adsorption capacity, better hydrophobicity, and increased distribution of counter ions at the interface. This condition reinforced the mutual repulsion force between liquid film surfaces and prevented further thinning of the liquid film, ultimately strengthening froth stability.

Eco-Friendly Collectors for Flotation of Fine Hematite and Malachite Particles

The separation of fine mineral particles, especially using environmentally friendly approaches, is one of the main problems in the processing of low-grade ores and the re-processing of mining tailings. This work assesses the potential of biosurfactants as collectors in the flotation of ultrafine (smaller than 20 μm) particles of hematite and malachite. As biosurfactants, we test acetylated acidic (ac-ASL) and lactonic sophorolipids (ac-LSL). In addition, n-dodecyl-β-D-maltoside (DDM) is used as a model non-ionic alkyl disaccharide surfactant, and sodium oleate (NaOl) is used as a reference. The biosurfactants are characterized using surface tension and foam analysis. The interaction of the minerals with the surfactants is characterized using zeta potential, solubility, and single-mineral flotation. The collecting properties of the surfactants are compared for the ultrafine (− 20 μm) and coarser (38–90 µm) particle size in the two-mineral flotation of hematite and malachite against quartz. The ultrafine particle size improves the grade in the oleate flotation of hematite, as well as the grades in the DDM flotation of hematite and malachite, which is explained by the weak interactions of the metal oxides with fatty acids and DDM. At the same time, the flotation with ac-LSL and ac-ASL is highly tolerant to the ultrafine particle size. These results indicate that biosurfactants are an interesting alternative to conventional petroleum-based surfactants in the flotation of Fe and Cu oxides. Moreover, a proper selection of surfactants can help combat the problem of fines.Graphical

Lagrangian reconciliation of expeditious analyzes on microflotation of hematite and dolomite by carboxylates

Microflotation campaign of a synthetic binary mixture of hematite and dolomite was carried out in order to evaluate the potential of saponified cottonseed oil as a collector. Hematite content was determined by expeditious methods, namely image analysis, pycnometry, and carbonate thermolysis by calcination. An algebraic reconciliation algorithm of redundant data (via Lagrange multipliers) was developed to treat the raw data from the different analytical techniques, aiming to increase the accuracy of the results, with the additional piece of information arising from product weighing, by introducing a dummy variable. At the stage of the study reported here, the physicochemical conditions for the selective flotation of hematite were not optimized; however, the results showed potential (both under acid and alkaline conditions) for the selective anionic flotation of the hematite/dolomite system. Prospective tests evaluating the analytical techniques employed showed pycnometry and calcination tended to be more reliable methods. Although the imaging method has shown promise, it still lacks some improvement in procedure for greater accuracy. The minimization of closure errors in mass balancing by using the mentioned optimization algorithm under constraints showed to be very relevant for the adequate evaluation of the separation process, using very small samples, as in the case of microflotation.

Effect of Solid Concentration and Particle Size on the Flotation Kinetics and Entrainment of Quartz and Hematite

Despite the importance of solid concentration in froth flotation, its effect on flotation kinetics and entrainment has rarely been studied. In this study, the flotation kinetics and entrainment in quartz and hematite single-mineral flotation systems as a function of the solid concentration and particle size were investigated using dodecylamine acetate as a collector. Kinetics modeling showed that the Gamma distribution achieved the best agreement with the experimental data, whereas the Classical and Klimpel models poorly fit the data (e.g., RMSE). The flotation rate constants (k) of both quartz and hematite at a higher solid concentration showed a concave shape, with the inflexion point at the middle-size range, whereas this trend altered at lower solid concentrations. Overall, quartz exhibited higher equilibrium recoveries (R∞) than hematite, which indicates its better overall rate constants. The degree of water recovery in both the quartz and hematite systems was higher at higher solid concentrations, but the hematite system exhibited higher water R∞ than the quartz system, meaning that the entrainment of gangue could be higher in direct hematite flotation than the reverse one. Therefore, a higher solid concentration is associated with better overall quartz recovery and can reduce hematite loss by entrainment during reverse flotation. An inverse relationship was identified between the solid concentration and particle size in terms of the ratio of water recovery to the concentrate. In the reverse flotation of iron ore, refraining from achieving equilibrium recovery could help limit entrainment, but this was not necessarily the case in direct flotation. No entrainment model or method other than the Warren and Ross model approximated the overall trends of flotation at the finest size range (−38 µm). However, extending the Warren method to polynomial distribution led to an improved fit with the experimental results. In addition to the solid concentration, particle density and size were revealed to be key to developing new entrainment models. Finally, after the fast recovery period (true flotation) was over, the slow recoveries were mainly driven by the slow-floating water fraction.

The molecular structure effects of starches and starch phosphates in the reverse flotation of quartz from hematite

Native starches and their phosphates with various molecular structures was introduced as the depressant to realize the flotation of quartz from hematite in this study. The present starch phosphates (WSP, NSP, GSP) were modified by the reaction between phosphate and three different corn starches (WS, NS, G50). The synthesis and characterization of starch phosphates found that starch with high amylopectin content was easily modified into starch phosphates. Microflotation tests showed that starch phosphates exhibited stronger depressing abilities of hematite flotation than native starches. Zeta potential measurement showed that both starches and starch phosphates could positively shift the zeta potential of hematite, while starch phosphates had more effects than starches. XPS and MDS indicated that the chemisorption occurred between Fe of hematite surface and CO groups of starch-based depressants. In addition, starch phosphates could adsorb onto the hematite surface through PO groups. MDS also presented that the adsorption strength of starch phosphate was mainly determined by the type and number of generating chelating rings, and the molecular structure of starch significantly affected the formation of chelate rings. The proposed adsorption model insights will significantly promote the development of starch-based depressants for iron ore flotation and other mineral processing applications.

Investigations on the reverse cationic flotation separation of quartz from hematite using polyaspartic acid as depressant

The depressant polyaspartic acid (PASP) was used to study its selective inhibition behavior in the reverse cationic flotation of hematite from quartz. Microflotation experiments were used to study the flotation behavior of hematite and quartz under different reagents, and artificial mixed mineral experiment was used to verify the separation effect of PASP on the two minerals. The selective adsorption mechanism of PASP on hematite surface was revealed by surface wettability analysis, zeta potential test, adsorption density test and X-ray photoelectron spectroscopy (XPS) analysis. Microflotation experiments showed that PASP was an efficient and selective hematite depressant under alkaline conditions. The artificial mixed mineral experiment proved that PASP can achieve efficient flotation separation of two minerals. Mechanistic experiments (Surface wettability analysis, zeta potential test, adsorption test, and XPS analysis) revealed that the depressant PASP selectively adsorbed on the surface of hematite, which significantly enhanced the hydrophilicity of the hematite surface and significantly negatively shifted its surface zeta potential. The depressant PASP was selectively chemisorbed on the surface of hematite mainly through the complex reaction between polar groups such as –NH- and –COO- in its molecule and the iron ion species on the surface of hematite.

Selective separation mechanism of hematite from quartz by anionic reverse flotation: Implications from surface hydroxylation

Reverse flotation desilication with anionic collector sodium oleate (OL) and activator Ca2+ is a common beneficiation method to purify hematite. Herein, the separation mechanism of hematite and quartz were systematically investigated by experiments and DFT calculations with the effect of surface hydroxylation fully considered. Flotation results showed that the success of anionic reverse flotation of hematite was inseparable from the activation of quartz by Ca2+. In addition, the use of sodium humate (HM), which selectively inhibited hematite, was also very critical. The Zeta potential revealed that the activator Ca2+ ions were highly selective for quartz and depression HM was highly selective for hematite. SEM clearly showed that Ca species were adsorbed on the quartz surface, which was confirmed as chemisorption by XPS. DFT calculations further confirmed that the adsorption of HM on the surface of hematite was more favorable than that of quartz, while Ca2+ on the surface of quartz was more favorable than that of hematite, and the chemisorbed Ca2+ ions on the quartz surface provided targeted reaction sites for the subsequent adsorption of OL, which enabled the activated quartz to overflow into the froth products, while the inhibited hematite to sink and concentrate in the flotation cell.

Adsorption of sodium oleate at the microfine hematite/aqueous solution interface and its consequences for flotation

The adsorption of sodium oleate (NaOL) at the microfine hematite/aqueous solution interface was investigated in this paper. Experimental research indicated that negative effects stemmed from the dissolution of the microfine hematite (D50=19.21 μm) could be effectively eliminated via the appropriate dosage of NaOL at alkali pH conditions. Solution chemistry calculation and adsorption test results indicated that RCOO− and (RCOO)22− ions were responsible for microfine hematite flotation at pH 8.2. Zeta potential and FTIR measurements confirmed the co-adsorption of molecular and ionic oleate species occurred at pH 8.2. X-ray photoelectron spectroscopy (XPS) results further indicated that oleate species interacted with hematite surfaces mainly through chemisorption, giving rise to molecule/colloid formation of oleate and Fe―OL complex compound. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) results demonstrated that oleate species adsorbed onto the hematite surfaces with a thickness of a few nanometers. Furthermore, the normalized peak intensity of C4H7+ ions on the hematite sample at pH 8.2 increased remarkably comparing with corresponding result of hematite sample at pH 6.8. The new findings of the present study well revealed the dissolution of microfine hematite and the pH effects on the hematite flotation, as well as the adsorption characteristics of oleate species.