Search Results (49)

The demand for rare earth elements (REEs) is continuously increasing due to the important roles they play in low-carbon and green energy technologies. Unfortunately, the global REE reserves are limited and concentrated in only a few countries, so the reprocessing of alternative resources like tailings is of critical importance. This study investigated carrier magnetic separation using coarse magnetite particles as a carrier to recover finely ground monazite from tailings. The monazite and carrier surfaces were modified by sodium oleate (NaOL) to improve the hydrophobic interactions between them. The results of zeta potential and contact angle measurements implied the selective adsorption of NaOL onto the surfaces of the monazite and magnetite particles. Although their hydrophobicity increased, heterogenous agglomeration between them was not substantial. To improve heterogenous agglomeration, emulsified kerosene was utilized as a bridging liquid, resulting in more extensive attachment of fine monazite particles onto the surfaces of carrier particles and a dramatic improvement in monazite recovery by magnetic separation—from 0% (without carrier) to 70% (with carrier). A rougher–scavenger–cleaner carrier magnetic separation can produce REE concentrates with a total rare earth oxide (TREO) recovery of 80% and a grade of 9%, increased from 3.4%, which can be further increased to 23.2% after separating REEs and the carrier. Full article

Regulating the dissolution and interfacial behavior of minerals via external force fields is considered a promising strategy for enhancing the flotation of soluble minerals. This study explored the potential of ultrasound-assisted pulp conditioning in improving ultrafine smithsonite flotation. Specifically, we systematically evaluated the effects of ultrasonic pretreatment (UP) on the physicochemical properties of smithsonite suspensions (focusing on surface erosion behavior) and assessed subsequent flotation performance using flotation tests and modern analytical techniques. It has been found that UP can significantly modify smithsonite suspension characteristics, including particle morphology, ionic composition, electrokinetic properties, and pulp pH. Flotation results demonstrate that UP yields higher recovery compared to traditional stirring (TS) conditioning, especially at medium-to-high sodium oleate (NaOL) concentrations. Comparative analysis reveals that ultrasonic-assisted dissolution and ion-selective migration are the main factors driving improved flotation performance. Unlike TS, UP promotes greater zinc ion release, facilitates the dissolution–hydrolysis–precipitation equilibrium, generates more and finer nanoparticles in the bulk phase, and induces the deposition of hydrozincite on smithsonite surfaces. These changes increase active zinc sites for more stable NaOL adsorption, thereby enhancing the flotation of ultrafine smithsonite particles. Full article

The increasing demand for sustainable mining practices has driven the development of environmentally friendly reagents for mineral processing. This study investigates vitamin E sodium succinate (VE_SS), a novel bio-based collector, for its potential in hematite flotation. The performance of VE_SS was benchmarked against sodium oleate (NaOL), a widely used conventional collector in mineral processing. To assess the flotation performance of VE_SS, micro-flotation experiments were conducted using hematite, sourced from a mine, and silica, a common associated gangue mineral. These tests were complemented by comprehensive surface characterizations, including contact angle measurements, zeta potential analysis, Fourier-transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS), to investigate the adsorption mechanisms of VE_SS in comparison to NaOL. The results demonstrate that VE_SS effectively enhances hematite recovery, achieving levels comparable to NaOL. Furthermore, VE_SS exhibited reduced sensitivity to pH, addressing a key limitation of NaOL, which performs well in neutral to alkaline conditions but shows significantly lower recovery under acidic pH. These findings highlight the potential of VE_SS as a bio-based alternative to conventional collectors, contributing to the advancement of more sustainable mineral processing practices. Full article

Ilmenite, the most widely distributed titanium ore resource globally, often coexists with titanaugite, one of its primary gangue minerals, which shares similar surface properties. This similarity significantly hampers the selective flotation separation efficiency of ilmenite. This study investigated the influence of grinding media shape—specifically steel balls, steel rods, and steel cylpebs—on the grinding characteristics of ilmenite and titanaugite through single-mineral micro-flotation experiments and related characterizations, and explored the potential of media shape to enhance the selective flotation separation of ilmenite. Experimental results demonstrate that in a weakly alkaline sodium oleate (NaOL) system at pH ≈ 8, the floatability of ilmenite milled with cylpebs is approximately 1.7% higher than that with balls and slightly lower than that with rods. In contrast, the floatability of titanaugite milled with cylpebs is similar to that with balls but almost 4% lower than that with rods. Compared to balls and rods, the difference in floatability between ilmenite and titanaugite increases from 29.96% and 29.04% to 32.71% with cylpeb milling. The primary reason is that cylpebs increase the exposure of the (104) face of ilmenite by approximately 2%, enhancing its interaction with NaOL, while minimizing the (−221) faces in titanaugite, thereby reducing its adverse impact on ilmenite flotation. Therefore, the use of cylpebs may facilitate the selective flotation separation of ilmenite. Full article

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. Full article

A new type of amino acid surfactant, lauroyl lysine (LL), is used as a green collector for the low-temperature flotation of quartz. The micro-flotation test results indicate that, under flotation conditions of 10–40 °C, pH = 11.0, 20 mg/L CaCl₂, and 60 mg/L LL, the highest recovery of quartz by LL could reach up to 97.08%. The temperature at which flotation occurs little impacts LL collection efficiency. In contrast, sodium oleate (NaOL) gives inferior performance to LL at all tested temperatures. The adsorption measurement and SEM-EDS results confirm that a quantity of LL is absorbed onto the quartz surface at low temperatures. Investigations into the interaction between the reagents and mineral surfaces are conducted using X-ray photoelectron spectroscopy (XPS) analysis, zeta potential measurements, and Fourier transform infrared (FT-IR) spectra. Findings indicate that LL is adsorbed onto the quartz surface through hydrogen bonds and intense chemisorption. Additionally, the amide groups in the LL molecular structure increase the solubility of the collector at low temperatures, and simultaneously, the amide bond can form an intermolecular hydrogen bond between O and H, which is conducive to quartz flotation. Full article

To investigate how hydrodynamic cavitation (HC) affects the adsorption of sodium oleate (NaOl) on diaspore and kaolinite surfaces, a comparative study on NaOl adsorption was conducted under different conditions. The flotation and separation of the minerals were also examined with and without HC pretreatment of NaOl. The results show that short-term HC pretreatment of NaOl solutions did not induce a measurable change in the chemical structure of NaOl, but produced micro-nanobubbles (MNBs) and resulted in decreases in the surface tension and viscosity of liquids. When MNBs interacted with minerals, their anchor on solids could affect the contact angles, zeta potentials, and surface NaOl adsorption toward minerals. At low NaOl concentrations, the presence of MNBs reduced the NaOl adsorption capacity and particles’ zeta potential while increasing the minerals’ contact angle. At higher NaOl concentrations, the presence of MNBs promoted NaOl adsorption, further increased the minerals’ contact angle, and further decreases the particles’ zeta potential. Additionally, the flotation and separation of minerals can be enhanced at low NaOl concentrations, largely due to the enhanced bubble mineralization through the selective surface-anchoring of MNBs on diaspore. However, the separation efficiency might deteriorate at high NaOl concentrations, though the presence of MNBs amplified the divergences in minerals’ surface wettability and zeta potentials. Full article

Due to the similar physical and chemical properties of ilmenite and olivine, separating them is challenging. The flotation process, with the use of collectors, is an effective method. In this study, a ternary collector consisting of aluminum ion (III), benzohydroxamic acid (BHA), and sodium oleate (NaOL) was prepared for the flotation separation of ilmenite and olivine. Through micro-flotation experiments, molecular dynamics simulation (MD), density functional theory (DFT), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (TOF-SIMS) analysis, the synergistic effect between the components of the ternary collector and the adsorption configuration on the surface of ilmenite was investigated. The results revealed that at pH = 8, Al (III), BHA, and NaOL could coordinate and adsorb effectively on the surface of ilmenite, enhancing its floatability for separation from olivine. The adsorption configuration differed from previous reports, showing a co-adsorption of multiple forms on the surface of ilmenite. Full article

The aim is to explore new depressants for achieving the efficient separation of apatite and dolomite. In this work, fucoidan (FD) was examined as an eco-friendly dolomite depressant to separate dolomite from apatite. The depression ability and adsorption mechanisms were investigated. The flotation results indicated that FD selectively depressed dolomite. The flotation difference between dolomite and apatite reached 70% approximately at an FD concentration of 75 mg/L. Meanwhile, the recovery and grade of P₂O₅ reached 89.84% and 32.88% and that of MgO decreased to 1.64% and 34.24% in the artificially mixed minerals test. Wettability, zeta potential, and Fourier transform infrared spectroscopy (FTIR) results revealed that FD tended to adsorb onto dolomite, impeding the interaction of sodium oleate (NaOL) with dolomite, but barely affected that on apatite. Microcalorimetry analysis indicated that the adsorption heat of FD on dolomite was much higher and less time was required to achieve equilibrium. X-ray photoelectron spectroscopy (XPS) results proved that the sulfonic acid radicals within FD chemically interacted with Mg atoms on dolomite while it weakly adsorbed on apatite. Full article

The synergistic effect of sodium dodecyl benzene sulfonate (SDBS) on the flotation separation of magnesite and dolomite using sodium oleate (NaOL) as a collector has been studied through flotation experiments, zeta potential measurements, contact angle measurements, Fourier transformation infrared spectroscopy analysis (FT-IR), particle size measurements and transmittance measurements. The flotation experiments show that when the synergist, SDBS, is added to the collector, NaOL, the collecting ability and ion resistance of NaOL can be improved so that the flotation separation of magnesite and dolomite can be realized. Zeta potential measurements, contact angle measurements and FT-IR analysis indicate that SDBS and NaOL can co-adsorb on the surface of magnesite. Particle size measurements and transmittance measurements show that SDBS can also improve the dispersion and solubility of NaOL in an aqueous solution, so as to achieve a synergistic effect. Full article

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

Flotation separation of magnesite from dolomite in the presence of SSZS (sodium silicate modified with zinc sulfate) as an inhibitor and NaOL (sodium oleate) as a collector has been studied via flotation tests, zeta potential measurements, contact angle measurements, and Fourier transformation infrared spectroscopy analysis (FT-IR). The flotation tests show that NaOL has strong collecting capacity in magnesite and dolomite flotation, so it is difficult to separate two minerals via flotation without inhibitors. SSZS is used as the depressant, which can selectively inhibit dolomite flotation and has little depression effect on magnesite. Zeta potential measurements, contact angle measurements, and FT-IR analysis indicate that SSZS can adsorb strongly onto dolomite’s surface and has a weak adsorption effect on magnesite. The adsorption of SSZS prevents NaOL from acting on the surface of dolomite. On the contrary, because there is little adsorption of SSZS onto magnesite, NaOL can still adsorb onto magnesite’s surface. Full article

The natural wettability of apatite and dolomite and the effect of sulfuric acid (H₂SO₄) and sodium oleate (NaOl) on the floatability and wettability of both minerals were studied using single-mineral flotation and contact angle measurement. The flotation experiments demonstrated that adding NaOl, apatite, and dolomite had good floatability. After adding H₂SO₄, the floatability of apatite decreased significantly. H₂SO₄ effectively inhibits apatite flotation. Contact angle measurements show that the use of H₂SO₄ induces a significant difference in surface wettability between apatite and dolomite. The moderate addition of H₂SO₄ can increase the contact angle of dolomite. In order to study the selective inhibition mechanism of H₂SO₄ in phosphorite flotation, molecular dynamics simulations (MDSs) were conducted to investigate the interaction between H₂SO₄ and fluorapatite and dolomite at the atomic–molecular level. The results of MDSs reveal that H₂SO₄ interacts with Ca sites on both fluorapatite and defective dolomite surfaces, hindering the interaction of NaOl with Ca sites on both mineral surfaces. SO₄²⁻ ions cannot prevent the interaction of oleate ions with Mg sites on dolomite surface. It is worth mentioning that SO₄²⁻ ions occupy the defective vacancies formed due to the dissolution of CO₃²⁻ on the surface of dolomite and interact with Ca sites. The remaining H₂SO₄ is subsequently adsorbed onto the surface of dolomite. Experimental and simulation results show that, due to the interaction of H₂SO₄ and NaOl, the surface of apatite can still undergo hydration forming a water molecule layer and maintaining a macroscopic hydrophilic property. In contrast, the oleate ions form an adsorption layer on dolomite transitioning it from a hydrophilic to a hydrophobic state. During the phosphate flotation process, the addition of an appropriate amount of sulfuric acid can further diminish the hydration of the dolomite surface, so that the surface of dolomite is more hydrophobic. Full article

Hydrogen bonds play an important role in the interaction between surfactants. In this study, the effect of three different ethoxylated alcohols (OP-10, NP-10, AEO-9) on the collecting behavior of sodium oleate (NaOL) in the flotation of quartz was investigated. To explore the mechanism, the hydrogen bond between ethoxylated alcohols and NaOL was analyzed using molecular dynamics (MD) simulation. The results showed that ethoxylated alcohols promoted the collecting performance of NaOL and reduced the dosage of the activator CaO and the collector NaOL in the flotation of quartz. The Zeta potential measurement illustrated that ethoxylated alcohols promoted the adsorption of OL⁻ on the activated quartz surface and the degree of promotion was in the order of OP-10 > NP-10 > AEO-9. The MD simulation results showed that a hydrogen bond presented between ethoxylated alcohols and OL⁻. Due to the hydrogen bond between the ethoxylated alcohols and OL⁻, the attraction force between OL⁻ and the quartz surface increased with the addition of ethoxylated alcohols in the order of OP-10 > NP-10 > AEO-9 based on the MD simulation results. As the result, the addition of ethoxylated alcohols increased the adsorption density of OL⁻ on the activated quartz surface, which explained the promotion of the collecting performance of OL⁻ in the flotation of quartz. Full article

The feasibility of producing high-density sintered magnesia with a one-step sintering method was investigated by utilizing finely ground magnesite as raw materials for direct flotation. The mechanism of flotation desilication of microfine grain magnesite was investigated by combining microstructure and chemical properties. The results showed that dodecylamine (DDA) has a sorting effect on magnesite reverse flotation desilication. Under the premise of 150 mg/L sodium polyacrylate (PAANa) as an inhibitor and 300 mg/L DDA as a collector, the content and recovery rate of MgO can reach 83.91% and 78.78%, respectively. When sodium oleate (NaOL) was used as a collector, the recovery rate of MgO was only 49.22%; therefore, it is unsuitable for magnesite purification. The flotation effect was affected because MgO particles and SiO₂ particles agglomerated in the flotation process. The flotation agent cannot work for a single element but works for the mineral agglomerate. While collecting Si elements, the agglomerated MgO was also brought into the froth layer, making flotation impossible. Full article