Oleate Flotation Research Articles

Enhanced Flotation Separation of Iron and Silicon with Branched Block Polyethylene Oxide Polypropylene Oxide and Sodium Oleate: Mechanisms and Flotation Behavior

This study explores the strengthening mechanism of the surfactant branched block polyethylene oxide–polypropylene oxide (BB-PEO-PPO) in sodium oleate (NaOL) flotation systems. A comprehensive characterization of BB-PEO-PPO was performed using flotation experiments, contact angle measurements, surface tension analysis, zeta potential measurements, infrared spectroscopy, and foam dynamics assessments. Flotation results showed that the combination of BB-PEO-PPO and NaOL improved iron recovery by 2.71% and reduced the total iron (TFe) grade in tailings by 2.05%, demonstrating a significant enhancement in collecting efficiency. The addition of BB-PEO-PPO effectively reduced foam size and lowered the zeta potential on the surface of activated quartz. At a slurry temperature of 15 °C, BB-PEO-PPO increased the solubility of NaOL radicals, facilitating their chemical adsorption onto activated quartz and improving the hydrophobicity of quartz particles. Notably, the presence of BB-PEO-PPO extended the flotation foam discharge time (D50) by 50% without substantially increasing foam volume, thereby significantly enhancing foam stability.

Effects of sodium oleate surface properties on the characteristics of two-phase foam in froth flotation

Aiming at the problem that the active agent foam is too stable during the flotation process, the experiments of the surface tension, surface viscoelasticity and gas-liquid two-phase foam performance of sodium oleate were carried out under the conditions of different concentrations, pH and temperature. The aim is to explain the changes in macroscopic blistering phenomena by changes in microscopic surface properties. The results show that concentration, pH and temperature all affected the foam properties of sodium oleate. When the sodium oleate solution is 10−3 mol/L (cmc), the foam stability is the best. The foam is most stable at pH of around 8.5. Temperature has a significant effect on the foaming property of sodium oleate, the foaming ability of sodium oleate is weak at a low temperature, while sodium oleate is unstable at high or low temperature. The lower the surface tension of the sodium oleate solution, the stronger the foaming performance; and the higher the expansion modulus, the more stable the foam. This study serves as a guide to control the parameters of sodium oleate flotation system and the optimal stabilisation of foam.

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

Study on the influence of particle size on the flotation separation of kaolinite and quartz

The influences of particle size on the flotation separation of kaolinite and quartz was explored by flotation tests of full-size and various sizes, zeta potential analysis. The flotation separation effects of kaolinite and quartz mixed minerals under different conditions were analyzed by calculating the characteristic parameters such as K, R ∞ , Km, SI and SE. Results show that in the sodium oleate scenario, kaolinite has better floatability under neutral conditions, while quartz has better floatability at pH 12. Ca 2+ has little effect on the floatability of kaolinite but it does inhibit the floatability of quartz under acid and weak alkali conditions. As well it can improve the floatability of quartz at a pH 12. In the two mineral flotation separation tests, reverse flotation had better selectivity for coarse-grained minerals. The maximum separation efficiency of the mixed ore with a particle size of 0.125–0.075 mm was 71.88%, the recovery of kaolinite in the concentrate was 84.97%, and the recovery of quartz amounted to 13.10%. It is of great significance to the research on the flotation separation of kaolinite and the high resource utilization of kaolinite. • 0.250–0.030 mm can be separated through positive and reverse flotation. • −0.030 mm fine kaolinite and quartz can't be separated by sodium oleate flotation. • When pH is less than 8, Ca 2+ is conducive to positive flotation separation. • Conforms the first kinetic model, reverse flotation has high separation efficiency.

Novel insights into the role of colloidal calcium dioleate in the flotation of calcium minerals

Previous studies on oleic acid systems have shown that calcium dioleate formed during the flotation process plays an important role. Calcium dioleate has been extensively studied as an important intermediate product in sodium oleate flotation of calcium-containing minerals sodium oleate, but its use as a collector to separate calcium-containing minerals remains unverified. The effect of calcium dioleate on fluorite, calcite and scheelite flotation and the adsorption mechanism on the mineral surface were examined using solution chemical analysis, flotation test, adsorption measurement, atomic force microscopy (AFM) and transmission electron microscopy (TEM) in this study. Solution chemical calculations prove that stable calcium dioleate colloid will be the dominant species at certain pH, calcium ion and oleate concentrations. Flotation experiments showed that the calcium dioleate plays an important role in the flotation process using sodium oleate. Calcium dioleate has better flotation effect for fluorite and scheelite but weaker effect for calcite than sodium oleate. Adsorption measurement showed that calcium dioleate is more easily adsorbed on the surface of scheelite and fluorite. AFM and TEM measurements exhibited that the formation of micelle adsorption on the surface of scheelite and fluorite caused by calcium dioleate clearly affects the surface roughness. Calcium dioleate colloids can likely enhance the surface roughness of scheelite and fluorite via selectively adsorption to improve the flotation of scheelite and fluorite.

Selective separation of hematite from quartz with sodium oleate collector and calcium lignosulphonate depressant

Iron ions activation of quartz is a tricky issue for efficiently sorting of target minerals in ferrous minerals flotation. The selection of an effective depressant is one of the most significant approaches to addressing this problem. In this study, the effects of calcium lignosulphonate (CLS), a widely studied novel depressant, on the flotation of Fe3+-activated quartz were investigated. The potential depression role of CLS in separating hematite from Fe3+-activated quartz in a sodium oleate (NaOl) flotation system was further explored. The flotation results indicated that the separation of hematite from quartz could be achieved by the selective depression of quartz in the presence of CLS. The results of zeta potential and spectroscopy analysis showed that CLS could absorb onto the surfaces of both hematite and Fe3+-activated quartz. The presence of CLS hindered the further adsorption of NaOl on quartz, whereas the NaOl adsorption onto hematite surfaces was limitedly affected. Compared with hematite, CLS might be more prone to react with the Fe sites on the surface of Fe3+-activated quartz, resulting in a relatively high final adsorption density on quartz surfaces, which was confirmed by X-ray photoelectron spectroscopy analysis and adsorption tests.

Selective flotation separation of andalusite and quartz and its mechanism

The separation of andalusite and quartz was investigated in the sodium oleate flotation system, and its mechanism was studied by solution chemical calculation, zeta-potential tests, Fourier transform infrared spectroscopic (FTIR), and X-ray photoelectron spectroscopic (XPS). The flotation tests results show that FeCl3·6H2O has a strong activation effect on andalusite and quartz and citric acid has a strong inhibitory effect on activated quartz, thus increasing the floatability difference between quartz and andalusite when the pulp pH is approximately 8. The FTIR, Zeta potential, and XPS analyses combined with the chemical calculation of flotation reagent solutions demonstrate that Fe forms hydroxide precipitates on the surface of andalusite and quartz and that oleate anions and metal ions adsorb onto the surface of the minerals. The elements Al and Fe can be chemically reacted. The anions in citric acid have different degrees of dissolution of Fe on the andalusite and quartz surfaces, thereby selectively eliminating the activation of the elemental Fe on andalusite and quartz and increasing the floatability of andalusite, leading to a better separation effect between andalusite and quartz.

Understanding the depression mechanism of citric acid in sodium oleate flotation of Ca2+-activated quartz: Experimental and DFT study

Quartz, a common gangue mineral, often coexists with the Ca-containing minerals in natural ore deposits, such as scheelite, apatite, fluorite and calcite. The depression of quartz in the flotation separation of these minerals is normally difficult, especially when the surface of the quartz is activated by Ca2+ ions dissolved from the calcium-bearing minerals. Thus, the search for an efficient depressant for Ca2+-activated quartz is urgent. In this study, citric acid (CA) was employed as a depressant for Ca2+-activated quartz. Microflotation results showed an improved depression efficiency of CA for the sodium oleate flotation of Ca2+-activated quartz. The depression mechanism of CA was evaluated through combined experimental and computational techniques, including zeta potential measurements, adsorption tests, Fourier transform infrared and X-ray photoelectron spectroscopy analysis, solution chemistry analysis, and density functional theory-based first principle calculations.

Use of citric acid and Fe(III) mixture as depressant in calcite flotation

Calcite, as a gangue mineral, needs to be removed from the target minerals in the flotation. Single depressant citric acid (CA) or Fe(III) species has a limited depressive effect on calcite in the sodium oleate (NaOL) flotation system. In this paper, the floatability of calcite with single depressant (CA or Fe(III)) and mixed depressant (CA /Fe(III)) was studied by microflotation experiments. Solution chemical calculation and X-ray photoelectron spectroscopy (XPS) analysis were used to explain the relevant depressive mechanism. Microflotation experiments indicate that the addition of Fe(III) greatly improves the depressive effect of the depressant CA on calcite. When mixed depressant Fe(III)/CA is used and the depressant dosages of Fe(III) and CA are all 1 × 10−4 mol/L, the recovery of calcite is only 3.9% at pH 8.5. The mixed depressant Fe (III)/CA can be co-adsorbed on the calcite surface. The Fe(III) species in the slurry react with CA species first and then co-adsorbed on the calcium atomic sites of the calcite. Moreover, the Fe(III) species is first adsorbed on the oxygen atom sites of the calcite, and then the Fe(III) species provides the adsorption sites for further adsorption of citric acid. Therefore, the mixed depressant Fe(III)/CA can be adsorbed at both the calcium atomic sites and the oxygen atomic sites of the calcite. The mixed depressant greatly improves the depressive effect on calcite, which is beneficial to the flotation separation of calcite and related useful minerals.

Role of calcium dioleate in the flotation of powellite particles using oleate

Micro-flotation, zeta potential, fluorescence emission, interface topography and XPS tests were carried out to investigate the flotation and adsorption of sodium oleate (NaOl) on powellite. Micro-flotation results show that the flotation recovery varies with different Ca2+ concentrations in pulps. The greater negative charge on the washed powellite (W-M) surface with both Ca2+ and Ol− compared to that with only Ol− could be explained by the additional adsorption of Ol− on the surface, along with calcium dioleate precipitation through hydrophobic interactions between hydrocarbon chains in the Ol− ion and Ca(Ol)2, as indicated by the results from zeta potential measurements. The most nonpolar powellite surface were obtained from raw powellite (R-M) with Ol− and washed powellite with both Ca2+ and Ol−, which is in good accordance with flotation and zeta potential test results. When the powellite crystal was equilibrated with a mixed solution of calcium chloride and sodium oleate, the surface roughness average increased greatly from 4.503 nm to 16.327 nm, revealing the formation of non-uniform clusters of Ca(Ol)2 precipitates. XPS analysis further demonstrates the release of Ca ions into powellite pulp and the removal of them by ultrasonic treatment. The adsorption of Ca(Ol)2 and oleate anions are responsible for the flotation of powellite using NaOl, and the former is more predominant. A suggested comparative model are given through molecular dynamics simulation analysis.

Effect of pulp temperature on separation of magnesite from dolomite in sodium oleate flotation system

Effect of pulp temperature on separation of magnesite from dolomite in sodium oleate flotation system

Comparative effects of sodium silicate and citric acid on the dispersion and flotation of carbonate-bearing iron ore

In the first stage of the stepped flotation, micro-fine siderite was recovered to eliminate its adverse impact on the reverse flotation of hematite. To achieve the maximum recovery of siderite, the micro-fine siderite needed to be dispersed from the hematite and quartz surfaces. The comparative effects of sodium silicate (inorganic dispersant) and citric acid (organic dispersant) on dispersion and flotation were investigated. In the dispersion experiments, the optimum dispersion of micro-fine siderite was achieved using 200 mg⋅L−1 sodium silicate or 100 mg⋅L−1 citric acid. Analysis of the surface zeta potential indicated that the surface potentials of the minerals became more negative after the addition of the dispersants, which contributed to the dispersion of the minerals. The surface potentials of hematite and quartz were also more negative in the citric acid solution than in the sodium silicate solution, and thus the citric acid had a better dispersion effect than the sodium silicate. However, better flotation performance was achieved in the starch‑sodium oleate flotation system with sodium silicate than that with citric acid. The FeO grade of the siderite concentrate was 13.91% with the addition of sodium silicate, whereas it was 11.93% with citric acid. The differences were further investigated by calculations based on the density functional theory. The calculated adsorption energies indicated that sodium silicate was able to adsorb on the minerals more stably than citric acid. The density of state and charge transfer showed that both dispersants were able to chemically adsorb on the hematite. However, hydrogen bonds only formed when sodium silicate adsorbed on hematite, which maintained the dispersion of siderite from the hematite. Therefore, sodium silicate is more suitable for dispersing micro-fine siderite from hematite and quartz in flotation.

Strengthened floatation of molybdite using oleate with suitable co-collector

The difference in flotation and adsorption mechanism of mixed sodium oleate (NaOl)/dodecylamine (DDA) and NaOl/cetyl pyridinium chloride (CPC) collectors on molybdite was comparative studied through micro-flotation, fluorescence emission spectroscopy, zeta potentials measurement, adsorption tests and FTIR measurement. The flotation results show that the best flotation of molybdite for 2 × 10−4 M NaOl, CPC and DDA is achieved at pH 7, 8 and 10, with corresponding mineral recovery of 64.3%, 40.9% and 44.5%, respectively. It is found that the collecting ability of single collector on molybdite is in the order of NaOl > CPC > DDA. For mixed system, molybdite recoveries with NaOl are improved by co-adsorbed DDA from about 75% to 95% with increasing DDA dosage, while no improvement is found in the case of mixed NaOl/CPC collectors. Fluorescence emission spectroscopy investigation displays the critical hemimicelle concentration (CHC) and critical micelle concentration (CMC) of NaOl are 2 × 10−4 M and 2 × 10−3 M, respectively. A larger micro-polarity of molybdite in mixed NaOl/DDA than that of mixed NaOl/CPC collectors is found. The adsorbed amount of DDA increase with the increasing DDA dosage due to the extra adsorption of DDA cations between the adjacent adsorbed NaOl ions, which leads to the less negative zeta potentials (from about −60 mV to −30 mV) of molybdite surface for mixed NaOl/DDA collectors. Above phenomenon and corresponding explanation are further confirmed by FTIR findings. Suggested models are presented to interpret the difference in adsorption mechanism of mixed NaOl/DDA and NaOl/CPC collectors on molybdite.

An investigation of the flotation minimum in the oleate flotation of hematite under alkaline conditions

Over the years there have been a number of instances describing a minimum in the flotation recovery of hematite in the alkaline pH region when oleate is used as the collector. These cases usually coincide with the use of a commercial oleate sample containing other fatty acids and/or salts as the collector. It is the purpose of this paper to provide experimental data involving the effects of pH on the flotation of a natural hematite sample using two collectors containing oleate and compare these data to changes in surface tension and bubble characteristics of aqueous oleate systems also as a function of pH. The main aim of this paper is to highlight and address this difference in hematite flotation behaviour with oleate solution characteristics and develop a better understanding of these interactions. It is proposed that this flotation minimum is associated with a reduction in both contact angle and bubble-particle flotation rate constant under these conditions, even though the surfactant solution chemistries would suggest that flotation should still be strong in this region.

New insights into the oleate flotation response of feldspar particles of different sizes: Anisotropic adsorption model

The anisotropic adsorption of sodium oleate (NaOL) on feldspar surfaces was investigated to elucidate the different flotation properties of feldspar particles of four different size ranges. Microflotation experiments showed that the feldspar flotation recovery of particles with sizes spanning different ranges decreased in the order 0–19>19–38>45–75>38–45μm. Zeta potential and FTIR measurements showed that NaOL was chemically adsorbed on the Al sites of the feldspar surface. The anisotropic surface energies and broken bond densities estimated by density functional theory calculations showed that, although feldspar mostly exposed (010) and (001) surfaces, only the (001) surfaces contained the Al sites needed for NaOL adsorption. The interaction energies calculated by molecular dynamics simulations confirmed the more favorable NaOL adsorption on (001) than (010) surfaces, which may represent the main cause for the anisotropic NaOL adsorption on feldspar particles of different sizes. SEM measurements showed that the main exposed surfaces on coarse and fine feldspar particles were the side (010) and basal (001) ones, respectively. A higher fraction of Al-rich (001) surfaces is exposed on fine feldspar particles, resulting in better floatability compared with coarse particles. XPS and adsorption measurements confirmed that the Al content on the feldspar surface varied with the particle size, explaining the different NaOL flotation of feldspar particles of different sizes. Therefore, the present results suggest that coarsely ground ore should be used for the separation of feldspar gangue minerals. Further improvements in the flotation separation of feldspar from associated valuable minerals can be achieved through selective comminution or grinding processes favoring the exposure of (010) surfaces.

The adsorption of oleate on powellite and fluorapatite: A joint experimental and theoretical simulation study

Flotation and adsorption performance of sodium oleate(NaOl)on powellite and fluorapatite were investigated in this work through micro-flotation tests, work of adhesion calculations, molecular dynamics simulation, micro-topography studies and FTIR measurements. The micro-flotation results show a similar flotation behaviors of powellite and fluorapatite under alkaline conditions, but a considerable difference in mineral recoveries in the pH range 2–7, which demonstrates the possibilities for separating powillite from fluorapatite under acidic conditions. The great difference in mineral recovery displays a good accordance with the obvious difference in the work of adhesion of powellite and fluorapatite at NaOl dosage range of 40–80mg/L, obtained from flotation and contact angle measurements, respectively. The more negative interaction energy (ΔE) between NaOl and powellite/water interface from molecular dynamics simulation reveals a more easily adsorption of NaOl onto powellite than onto fluorapatite, which excellently matches with the results of flotation and work of adhesion. The results of micro-topography study shows that the adsorption of NaOl on powellite is mainly ascribed to the chemisorption of oleate ions with Ca2+ on powellite lattice or the precipitation of calcium dioleate agglomerates on powellite surface when it was in the solution without or with Ca2+, respectively. The FTIR measurements further confirm the chemisorption of oleate ions with Ca2+ active sites on powellite surface.

Surface crystal chemistry of spodumene with different size fractions and implications for flotation

Abstract The flotation and adsorption of sodium oleate (NaOL) on spodumene with four different particle size fractions (45–75 μm, 38–45 μm, 19–38 μm and 0–19 μm) were investigated. The flotation recovery increases upon slightly decreasing the size fraction, reaching a peak value at a size fraction of 38–45 μm. The recovery then decreases gradually upon further decreasing the particle size over the entire investigated range of solution pH values. The specific chemisorption sites for the anionic NaOL collector are the Al sites on the surface of negatively charged spodumene, which is confirmed by FTIR and zeta potential measurements. Anisotropic surface energies and broken bond densities are calculated based on density function theory (DFT) to characterize the surface chemistry of spodumene crystal planes. The anisotropic adsorption behavior of NaOL on different crystal planes of spodumene is studied in terms of adsorption conformations and interaction energies by molecular dynamics (MD) simulations. It is demonstrated that NaOL prefers to bind in a monodentate chelating complex configuration to the most stable surface plane, the (1 1 0) plane, which has two broken Al O bonds. The (1 1 0) plane of spodumene is more favorable for chemisorbing NaOL than the (0 0 1) plane, which has one broken Al O bond. The flotation behavior of spodumene with different particle sizes is well explained by the surface crystal chemistry. Based on the findings of this work, further improvement in spodumene flotation is possible if a selective comminution or grinding process is used that favors the production of (1 1 0) planes.

Removal of sulfate ions by dissolved air flotation (DAF) following precipitation and flocculation

The removal of sulfate ions from wastewater is an environmental challenge faced by several industrial sectors, such as the mining, metallurgical, chemical and petrochemical industries. Most existing options are inefficient and costly, particularly for sulfate-bearing acid mine drainage (AMD; coal and metal sulfides). This work focused on the precipitation of sulfate with polyaluminum chloride at pH4.5 at the bench scale and their separation by flotation. However, these hydrophilic precipitates did not float via dissolved air flotation (DAF) and needed to be flocculated with cationic polyacrylamide. The best removal of sulfate-sodium salts from solution was obtained using an Al/SO42− molar ratio of 4:1 and 20mg·L−1 of polymer flocculant. The sulfate-bearing flocs were readily removed from the aqueous solutions by microbubbles (MBs, 30–100μm) and nanobubbles (NBs, 150–800nm). The separation was very rapid and followed a first-order flotation kinetics model with a high rate constant of 4.1min−1. The results were validated using AMD generated by a coal mine with a sulfate concentration of 1753mg·L−1, and the anion concentration was rapidly reduced to below the World Health Organization (WHO) standard of 500mg·L−1. Attempts to improve the removal efficiency with sodium oleate flotation collector and conditioning with NBs were not successful. The maximum removal percentage (80–82% of the feed content) appears to be limited by the efficiency of the DAF process and the chemical equilibrium of the precipitates, which leaves some soluble sulfate in solution. Bubbles readily attach to the flocs and become entrained and/or entrapped in the flocs, creating aerated flocs. Because all of these mechanisms operate simultaneously, the flotation of the flocs is very rapid, as indicated by the high kinetics rate constant. We concluded that the DAF of sulfate-loaded flocs has potential for the treatment of voluminous sulfate-bearing effluents, including coal AMD, at high superficial rates.

Surface chemistry and oleate flotation of three South Australian micaceous hematites

Previous surface chemical and flotation publications involving natural hematites have mainly focussed on the so-called massive hematites, but little has been published on the characteristics of micaceous or specular hematites which find specialist applications as pigment grade iron oxides. These include use in protective paints and as an additive in resin fillers. The surface chemistry and oleate flotation characteristics of three South Australian micaceous hematites (Warrakimbo, Williamstown and Iron Knob) have been examined using zeta potential, surface titration and oleate flotation techniques. The optimum technique for investigating the surface chemical properties as a function of pH was the surface titration technique, since inherent silica in the natural hematite samples can dominate the zeta potential measurements, even though it often represented less than 1% of the overall mineral assemblage. It was also found that both oleate solution chemistry and mineral surface characteristics dominated the flotation behaviour of these hematites. Maximum hematite recoveries were obtained at neutral pH values, close to the zero point of charge of the hematites. Chemisorption was confirmed as the dominant mechanism of oleate adsorption on the surface of the hematites.

Effects of Eh and pH on the oleate flotation of iron oxides

Most articles published on the flotation of iron oxide minerals with oleate involve the effects of pH on the interfacial properties of the iron oxides as a function of pH, together with some attention given to the solution chemistry of the collector. It was the purpose of this study to examine what effects changing the electrochemical potential of the solution, as well as changing the pH, had on the flotation kinetics and recovery of three iron oxide minerals using sodium oleate. The results of this study confirmed the importance of the stability of ferric oleate on the surface of iron oxide minerals as a significant requirement for their flotation. The iron oxide minerals used were hematite, magnetite and goethite. Flotation kinetics could readily be simulated using a first order model, allowing the prediction of first order rate constants and ultimate recoveries. Values of these parameters were consistent with the region of stability of the ferric oleate on an Eh vs. pH equilibrium diagram for aqueous ferric oleate. Flotation of iron oxides in the acidic pH region was postulated to be promoted by the adsorption of insoluble or colloidal oleate species.