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In order to enhance the reverse flotation effect of hematite, dodecyl trimethyl ammonium chloride (DTAC) and a mixed anionic/cationic collector of DTAC and tall oil were selected for flotation studies on quartz and hematite. Surface tension tests, FT-IR, XPS analysis, and molecular dynamics (MD) simulations were also conducted in order to investigate the interaction mechanism of the mixed collector on the quartz surface. The results revealed that, at a natural pH (approximately 7.0) and 298 K, and with a dosage of 20 mg/L for the mixed collector (mDTAC:mtall oil = 3:1) and 4 mg/L for causticized starch, the recovery rates of quartz and hematite were 94.67% and 8.69%, respectively. Compared to the use of a single DTAC, the mixed DTAC/tail oil collector enhanced the flotation effect under constant variables. Additionally, a comparison of temperature and surface tension for monomineral flotation and artificially mixed ore flotation tests showed that the mixed collector was less influenced by temperature, compared to the single DTAC, and exhibited good resistance and more effective separation of quartz and hematite at lower temperatures. The analysis of FT-IR, XPS, and MD simulations revealed that the single DTAC collector primarily adsorbed onto quartz through physical adsorption and hydrogen bonding, while the combination of tall oil and DTAC enhanced the adsorption of the collector on the quartz surface. [ABSTRACT FROM AUTHOR]

Water quality, particularly hardness, plays an important role in affecting the floatability of minerals as it interferes with the chemical/electro-chemical characteristics of mineral surfaces and their interactions with flotation reagents. It could become unpredictable when water sources characterized by different calcium or magnesium ion distributions were involved. This study aimed to identify the role of Ca2+/Mg2+ ions in the recycled water on the cationic reverse flotation selectivity of iron oxides through a series of bench/micro flotation tests, zeta potential, powder contact angle, and Fourier Transform Infrared (FTIR), etc. The results pointed out that the use of recycled tailing water deteriorates the flotation selectivity and dilutes the concentrates. This can be largely attributed to the presence of Ca2+ ions at higher concentrations as they induce a drop in the Fe recovery and an increase in SiO2 content while an increase in the content of Mg2+ ions seems to have little effect on the quality of concentrate. As evidenced by the data from micro-flotation, powder contact angle, zeta potentials, and FTIR, a hydrophilic colloidal layer formed by Ca-based hydrolyzed compounds, such as Ca(OH)+ or, CaCO3(s), etc., on quartz could change its zeta potentials and disturb its interactions with a cationic collector. They also play a role in weakening the flocculation of starch on hematite probably by prelocking the acidic groups on the starch remnants and contracting their configurations, thus preventing their adsorption on mineral surfaces. However, magnesium ions seem to be beneficial to in strengthening the flocculation of starch on hematite as magnesium-based species could act as adsorption bridges of between starch and mineral surfaces. [ABSTRACT FROM AUTHOR]

Dolomite, a prominent calcium-bearing gangue mineral found in carbonate-type zinc oxide ores, poses a significant challenge for effective flotation separation alongside smithsonite due to their highly similar surface properties. The present study explores the potential of 2-(4,4-dimethylpentan-2-yl)-5,7,7-trimethyloctanoic acid (2-DMPT) as a collector for the reverse flotation of smithsonite from dolomite. Micro-flotation experiments indicated that saponified 2-DMPT exhibited superior collecting ability and selectivity for dolomite over smithsonite under highly alkaline conditions. Specifically, the flotation recovery of dolomite reached 62%, whereas only 6% of smithsonite was recovered in the flotation foam products. Zeta potential and attenuated total reflectance–Fourier transform infrared (ATR-FTIR) analysis revealed that changes in pH values had minimal influence on the collector's adsorption onto dolomite, while significantly hindering its adsorption on the smithsonite surface. Furthermore, X-ray photoelectron spectroscopy (XPS) analysis showed that 2-DMPT could form hydrophobic complexes with the active Ca2+ sites on the dolomite surface at pH 11.5. However, the interaction between smithsonite and carboxylic groups of 2-DMPT under the same conditions was relatively weaker, facilitating their reverse flotation separation. As a result, 2-DMPT shows promise as a potential collector for the reverse flotation process, effectively removing dolomite from smithsonite and reducing acid consumption in subsequent acid-leaching processes. [ABSTRACT FROM AUTHOR]

In this study, the influence of activating treatment on the demineralization of a lignite sample utilizing the reverse flotation was studied. A lignite sample containing 42.09% ash, 0.86% sulfur, 38.46% volatile matter and 19.45% fixed carbon was used in experiments. Quartz, clay mineral, feldspar (plagioclase) mineral and mica mineral were determined as dominant minerals. The activation of gangue minerals (particularly quartz) using lead, tin, iron, and aluminum salts were performed. The influences of different parameters were investigated. Reverse flotation results demonstrated that a clean coal having 35.81% ash and 61.81% combustible yield could be gained in the usage of tin salt. [ABSTRACT FROM AUTHOR]

In this study, an optimized method was presented for the reverse quartz flotation in iron ore purification where sodium oleate (NaOL) was always selected as the collector due to its accessibility and economic benefits. Three alcohol ethoxylates, octylphenol ethoxylate (OP-10), nonylphenol ethoxylate (NP-10) and fatty alcohol ethoxylates (AEO-9) were introduced to improve the collecting performance of NaOL in the reverse flotation of quartz. It turned out that the addition of alcohol ethoxylates was helpful to increase the recovery of quartz in the flotation with the order of OP-10 > NP-10 > AEO-9. To characterize the adsorption of NaOL on activated quartz in different surfactant systems, Fourier-Transform Infrared Spectroscopy (FTIR) and Quartz Crystal Microbalance with Dissipation (QCM-D) were employed. Furthermore, the contact angles of the quartz surface that interacted with different surfactant systems were measured to investigate the synergy effect of NaOL and alcohol ethoxylates on the hydrophobicity of quartz. It turned out that alcohol ethoxylates promoted the adsorption of NaOL on the activated quartz, resulting in an increase in the hydrophobicity of quartz also in the order of OP-10 > NP-10 > AEO-9, which well explained the flotation results. Regular Solution Theory (RST) and the dilution effect based on the surface tension analysis were utilized to elucidate the synergy mechanism between NaOL and the alcohol ethoxylate. [ABSTRACT FROM AUTHOR]

Purpose. In this work, the influence of flotation reagents on the separation yield of the phosphate-carbonate system is studied. The investigation is conducted by the reverse flotation process in double stage of the phosphate ores from the Jebel Onk deposit-Algeria. Methodology. The experimental part can be divided into three aspects, a mechanical preparation of the samples, and flotation tests in the first stage followed by a double flotation and, finally, characterization of the flotation products by different physicalchemical analysis techniques. Findings. Reverse flotation double stage process was applied on two classes of phosphate ores (C1: 40–250 and C2: 250–500 μm). The samples are constituted by phosphatic elements (apatite), cemented by a mixture of a great amount of dolomite with low amounts of quartz, clay and calcite. Flotation results showed that P2O5 recovery was higher for C2 compared to C1. Thus, oleic acid and double tartrate of sodium-potassium could be considered as the best reagent since the P2O5 recovery content corresponds to 29.27 and 31.25 % for C1 and C2, respectively. Compared to the oleic acid and pine oil reagent, the recoveries of P2O5 were 28.85 and 30.55 % for C1 and C2, respectively. However, when other reagents as (oleic acid + phosphoric acid) and (oleic acid + diesel fuel) were used, the recovered amount of P2O5 was found to be less important, 27.80 and 27.10 % for class C1, and 30.14 and 29.15 % for C2, respectively. Originality. During this study two main axes were discussed: the first one was the influence of flotation reagents on flotation of the first and second stages, the second one was to study the effect of grain size on the flotation yields. The flotation process has been shown to be effective both in terms of depressed phosphate elements in the phosphate concentrates and in gangue floated in the flotation tailings. It can be seen that the concentrate contents of around 32 % is achieved in P2O5 with superior recoveries of 99 %. Practical value. The results of analyses carried out on the flotation products showed, in most cases, that the streams are richer in phosphate elements (fluorapatite, carbonate hydroxylapatite, carbonate fluorapatite) and a low amount of carbonates (dolomite and calcite), unlike floating, mainly made up of dolomite with a small amount of phosphated elements. [ABSTRACT FROM AUTHOR]

To improve the magnesia removal effect of collophane and increase the P2O5 grade of phosphorus concentrate, the fatty acid collector mixed with sodium dodecyl sulfate (SDS) was used as the compound collector in reverse flotation for magnesia removal in acid system. Solution surface tension measurement, Zeta potential test and infrared spectrum analysis were conducted to analyze the intensified effect of compound collector for dolomite removal. The results showed that under the conditions of grinding fineness -0.074 mm accounted for 89.8%, sulfuric acid dosage 12.0 kg/t, phosphoric acid dosage 3.0 kg/t, SDS compound proportion 3%, collector dosage 1.0 kg/t, the P2O5 grade of concentrate is increased from 25.7% to 29.94%. SDS can reduce the surface tension of slurry, which is conducive to the formation and stability of flotation foam. Zeta potential became negative due to the compound collector adsorbed on the mineral surface. Moreover, the -CH2 antisymmetric stretching vibration peak originated from fatty acid and SDS were detected after the interaction of collectors with dolomite. The compound collector was effectively adsorbed on the surface of dolomite, enhancing the magnesium removal effect of collophane. [ABSTRACT FROM AUTHOR]

A study into the possible separation of feldspar from quartz in a Bangladesh river sand sample was undertaken with the aim of producing a high-grade quartz product for potential use in glassmaking. Flotation was used to upgrade two river sand concentrates, with sizings of +250 µm and −250 µm, from the Brahmaputra River. Feldspar was floated from quartz using dodecylamine as collector in an acidic circuit at pH 2–2.5 after a mica prefloat. For the −250 µm fraction, the best quality quartz product assayed 96.8 wt% SiO2 and 1.95 wt% Al2O3 with 46.7 wt% of the feed quartz recovered at a quartz content of 89.1 wt% quartz. A test on the +250 µm fraction, which was firstly ground then deslimed at 50 µm before mica and feldspar flotation stages, produced a quartz product assaying 99.5 wt% SiO2 and only 0.3 wt% Al2O3 with a quartz content of 98 wt%. [ABSTRACT FROM AUTHOR]

It is critical for water quality in flotation as it dramatically influences the chemical/electrochemical properties of mineral surfaces and their interactions with reagents. Many potential variations could alter the water chemistry: water recirculation, mineral dissolutions, reagent additions, etc. This study aimed to identify the key elements from the recycled water sources affecting the separation efficiency in a typical industrial flotation circuit of iron oxides through a series of bench/micro flotation tests, zeta potential measurement, etc. The built-up and distribution of the dominant cations/anions in the process water from the roughers in the flotation system was also analyzed and recorded by Inductively Coupled Plasma-Optical Emission (ICP-OES) for a period of about three months when the operations were stable. The flotation results pointed out that a concentrate with a sharp increase of 6.0% Fe recovery and 2.5% SiO2 content was obtained by using the recycled tailing water only in comparison by using fresh water. In contrast, a slight uptrend in the grade of Fe but a substantial loss of near 6.5% Fe recovery occurs by using the treated sewage water alone instead. This could attribute to the ion distributions in these water sources, in which Ca2+, Fen+, Mg2+ or SO42- ions were determined as the key ions influencing the flotation behaviors of the iron ore. But the competitive effects of Fe3+ ions were more significant than the ones of Ca2+ or Mg2+ ions. And the occurrence of starch could deteriorate the dilution of silicates in concentration induced by Fe3+/Fe2+ ions. It can be explained by zeta potential measurement or solution chemistry of those ions, indicating that at 8.5-9.0, the coating of the precipitates of Fe(OH)3(s) induced by iron ions alters a reverse on the zeta potentials of quartz. The presence of SO42- ions, however, has a positive role in reducing the possibility of slime coating on silicates due to acting as a chelating agent of iron ions. [ABSTRACT FROM AUTHOR]

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The dissolution characteristics of minerals, dissolution of flotation agents in solutions, and equilibrium of dissociations and associations serve as the basis for determining the optimal conditions for the effective components of flotation agents and for evaluating the interaction between flotation agents and minerals. This basis provided the theoretical support for the flotation separation of minerals. Based on this, the flotation separation of magnesite and calcite was realized using sodium dihydrogen phosphate, also known as monosodium phosphate (MSP), as a regulator and dodecylamine (DDA) as a collector. When MSP was used in the DDA system, single-mineral and binary mixed-ore flotation tests revealed that the floatability of calcite was significantly greater than that of magnesite and the separation of magnesite and calcite was more effective, respectively. Zeta potential measurements showed that MSP-containing negative groups could selectively reduce the zeta potential of calcite and promote the adsorption of DDA-containing positive groups on the surface of the calcite. However, this effect was negligible on the zeta potential of magnesite. Due to the stronger affinity of MSP to Ca2+ than that to Mg2+, as demonstrated by Fourier transform infrared and X-ray photoelectron spectroscopy analyses, the MSP was adsorbed onto the surface of calcite primarily by hydrogen bonds rather than magnesite, which promoted the stronger adsorption of DDA-containing positive groups on the surface of the calcite. As a result, the differences in the floatability of magnesite and calcite were enlarged by MSP. Thus, MSP can be utilized an effective regulator for the efficient separation of magnesite from calcite via reverse flotation. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Flocculation reverse flotation of microfine-grained chlorite and hematite. • Application of CPAM containing ester groups as a novel hydrophobic flocculant. • Selective flocculation of microfine-grained chlorite. • Analyzed the adsorption mechanism of CPAM on the surface of hematite and chlorite. • Visualized the analysis of the wrapping angle between chlorite and bubbles. [ABSTRACT FROM AUTHOR]

The depletion of high-grade iron ores has necessitated the beneficiation of low-grade iron ores. Flotation is considered the most efficient operation to upgrade the iron content of fine-grained ores that do not respond to gravity or size classification units. Out of several reagents used in iron ore reverse flotation, depressants play a crucial role in selectively making the iron oxides hydrophilic and prohibiting them from reporting to the gangue-rich froth phase. Starch is widely used as the depressant in iron ore flotation. The present paper attempts to highlight different facets of starch as an iron ore depressant. It reviews the important research papers that discuss the origin and chemistry of starch, starch-iron oxide interaction mechanism, and the application of different types of starches and their alternatives in iron ore flotation. [ABSTRACT FROM AUTHOR]

This work aimed to upgrade a low-grade sedimentary phosphate ore through attrition scrubbing/desliming and an anionic/cationic reverse flotation technique. The mineralogical and chemical examination showed that the sample contained low-grade apatite minerals (P2O5 ~ 22.5%), and the main associated gangue minerals were gypsum and quartz. The effects of both collector and depressant dosage were investigated and optimized in each individual flotation process. The results of attrition scrubbing accompanied by desliming showed that a high content of P2O5 (27.97%) with a recovery of 72.1% was obtained in the coarse size fraction (+53 µm), and the majority of quartz and gypsum separated in the fine size fraction (−53 µm). The effect of using a new tall oil collector mixture was investigated during the anionic reverse flotation. Sodium tripolyphosphate (STPP) was used as a phosphate depressant during anionic and cationic reverse flotation. The flotation results of the deslimed sample demonstrated that cationic reverse flotation was much more desirable in terms of achieving a high grade and recovery of P2O5 compared to anionic reverse flotation. Considering the statistical design, a maximum grade of 31.23% P2O5 with a recovery of 95.22% was obtained in the non-floated fraction using 950.88 g/t of the collector (amine) and 500 g/t of the STPP. [ABSTRACT FROM AUTHOR]

In this study, an imidazole ionic liquid (dodecyl-tri-methylimidazolium chloride) was employed as a collector to separate quartz from phosphorite. The micro-flotation experiments of a single mineral found that it had selective collecting ability for quartz than phosphorite. Mixed mineral flotation experiments confirmed that efficient separation results could be obtained using the imidazole ionic liquid as the collector. A concentrate with a 31.44% grade of phosphorite could be obtained with a 0.285 kg/Mg collector dosage at neutral pH, which was much better than the traditional collector dodecylamine. The adsorption mechanism of the imidazole ionic liquid on the surface of phosphorite and quartz was investigated by contact angle and zeta potential measurements, Fourier transform infrared and X-ray photoelectron spectroscopy analyses. These results showed that the adsorption of imidazole ionic liquid at the quartz surface was stronger than that of phosphorite, and the collector adsorbability difference between quartz and phosphorite resulted in the efficient flotation separation. Consequently, the dodecyl-tri-methylimidazolium chloride salt is an effective collector for reverse flotation of quartz from phosphorite. [ABSTRACT FROM AUTHOR]

Most iron reserves are low in grade with quartz as the main gangue mineral, and anionic reverse flotation has become the most crucial separation method in the processing plants of iron ore. Thus, a flotation feed sample that is a mixture of low-intensity and high-gradient magnetic separators concentrates was acquired from a processing plant. The sample characterizations with X-ray diffraction (XRD), X-ray fluorescence (XRF), laser particle size analyzer, and mineral liberation analysis (MLA) confirmed that the sample consists of iron oxide as a valuable mineral and quartz as a gangue mineral with adequate liberation degree. In the anionic reverse flotation, the interaction of the flotation reagents with the constituents of the feed makes the flotation a complex system. Thus, the selection and optimization of regent dosages were performed using a uniform experimental design to estimate the optimum separation efficiency. The optimum reagent system was 1.6 kg/Mg starch depressant, 1.0 kg/Mg calcium oxide (lime) activator, and 0.8 kg/Mg TD-II anionic collector. At the optimum, 68.90% iron grade with 92.62% recovery was produced. [ABSTRACT FROM AUTHOR]

Depressant carboxymethyl chitosan (CMCS) was introduced to reverse flotation of quartz from hematite using collector DDA. Microflotation experiments presented that CMCS completely depressed the hematite flotation while it had little effect on quartz flotation. The mineral mixture flotation confirmed the reagent scheme of DDA/CMCS could achieve efficient separation of quartz from hematite. It was also found that CMCS has better selective depression ability than the widely-used starch. Zeta potential measurements illustrated that CMCS could prevent DDA adsorption onto the hematite surface, while it did not affect the interaction between DDA and quartz surface. X-ray photoelectron spectroscopy (XPS) indicated that CMCS interacted with the Fe(III) components of hematite by chemisorption, which was stronger than the bonding between starch and hematite. Molecular dynamics simulation (MDS) further revealed the twice interaction energy of CMCS with (001) hematite surface than that of starch. Hence, CMCS has the potential to replace starch in practice. [Display omitted] • CMCS was firstly utilized as a depressant for the reverse flotation of quartz from hematite. • CMCS presented better performance than widely-used depressant starch. • CMCS was hardly adsorb onto the quartz surface. • CMCS interacted with Fe(III) species at the hematite surface by chemical adsorption. • CMCS has twice interaction energy with (001) hematite surface than starch. [ABSTRACT FROM AUTHOR]

Magnetite reverse flotation using a new deep eutectic solvent synthesized by lactic acid and CTAC as the collector has been investigated in this work. The flotation test results were compared with dodecylamine. The CTAC/lactic acid DES increased the grade of total iron to 66.69%, and the reduce quartz content to 6.67%, which were preferable to dodecylamine (the grade of Fe in the concentrate is 63.47%, and the grade of quartz in the concentrate is 9.13%). The depression performance and adsorption mechanism of CTAC/lactic acid DES on surface of magnetite and quartz are investigated by FT-IR, zeta potential and XPS. The results show that the adsorption of CTAC/lactic acid DES on quartz surface is more effective than that of magnetite. Therefore, deep eutectic solvent is an effective reagent for reverse flotation of magnetite as collector. [ABSTRACT FROM AUTHOR]

The processing of e-waste is gaining importance worldwide as it contains a large number of valuable metals. In the present investigation, an attempt has been made to analyze the influence of surfactants on the flotation of printed circuit boards. Flotation kinetic studies have been carried out by varying different surfactant combinations such as C0F0 (without surfactants), C0F1 (only frother), C1F0 (only collector), and C1F1 (collector and frother). A first-order kinetic model has been proposed to explain the recovery of metallic and non-metallic particles. The hydrophobic plastic particles could be recovered to the froth products without surfactants. The addition of collector and frother imparts movement of few metallic particles to the froth products causing a decrease in the recovery of metals to the non-froth products (Cu recovery decreased from 92% to 72% and Sn recovery decreased from 90.1% to 65%). However, the frother is essential to impart stability to the froth and facilitate transportation of particles to the froth products. Frother alone can satisfactorily separate metallic and non-metallic particles. [Display omitted] • Separation of hydrophilic metallic and hydrophobic non-metallic particles could be achieved through flotation. • Waste printed circuit board flotation follows first-order rate kinetics. • No surfactant is needed to float powdered plastic and polymer components. • Froth product is enriched in plastic, glass fiber, and ceramic particles. • Non-froth product is enriched in metallic particles of Cu, Sn, Pb, Fe, etc. [ABSTRACT FROM AUTHOR]

Reverse flotation of collophanite at natural pH could significantly decrease the cost of pH regulators. In this study, isooctyl polyoxyethylene ether phosphate (AEP) was tested as a new surfactant in the reverse flotation of collophanite. Micro-flotation tests were conducted, and the adsorption mechanism of the new collector was analysed using X-ray photoelectron spectroscopy (XPS) and zeta potential analyses. The results of the flotation tests demonstrated that AEP could enable dolomite to float under natural pH (pH=7.2) and showed profound selectivity towards dolomite as opposed to fluorapatite. Based on the zeta potential and XPS results, the adsorption phenomena are mainly attributed to calcium active sites on both mineral surfaces. Dolomite possesses more magnesium active sites than fluorapatite, which tend to reinforce the interaction effect between AEP and dolomite. Furthermore, when compared to CO3 ²-ions on the dolomite surface, PO4 3- ions on the fluorapatite surface tend to exhibit a stronger hindrance to the adsorption of AEP on the fluorapatite surface. This is attributed to their larger volumes and more charges on their surfaces, thereby causing a floatability difference between the two minerals. [ABSTRACT FROM AUTHOR]

2-((2-(decyloxy)ethyl)amino)lauric acid (C10H21CH(NH(CH2)3OC10H21)COOH, (LDEA), a novel amphoteric surfactant, has been first utilized as the collector for on-site the reverse flotation of Anqian mixed magnetic concentrates. The separation performances were investigated systematically by flotation conditioning tests, open-circuit flowsheet experiment, and locked cycle flowsheet test. The flotation condition test's results showed that the optimal roughing conditions were pulp pH of 10, starch dosage 1000 g/Mg, and LDEA dosage of 500 g/Mg at 25 °C. Under the optimized flotation conditions, through one roughing - three scavengings locked cycle flowsheet, the iron concentrate with a total iron grade of 68.08% and recovery of 88.20% was obtained. In contrast, the iron grade of the tailings was only 12.32%. Compared with the flotation results of anionic commercial surfactant RA-715 used as the collector, the LDEA has a better separation performance. The iron grade and recovery increased by 0.07% and 0.86% in the iron concentrate, and the grade of the tailings decreased 3.72%, respectively. Besides, the LDEA possesses more advantages, such as a simple flotation process, no activator (CaO) addition, lower collector consumption, and lower pulp temperature. The study revealed that the novel amphoteric surfactant LDEA was an effective flotation collector with good collecting and separation ability on natural iron ores at a comparatively lower temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] • The selective absorption of NaOL with NP-10 on dolomite surface was examined. • The selective co-absorption mechanism of NaOL with NP-10 was revealed. • NP-10 promoted the adsorption of NaOL on dolomite surface. • A selective absorption model of NaOL with NP-10 was established. • Flotation separation of dolomite from apatite was achieved with mixed collectors. Surfactants were introduced to enhance the efficiency of sodium oleate (NaOL) in the flotation-based separation of calcium-containing minerals due to the drawbacks of substantial dosages and limited selectivity of NaOL. This study investigates the synergistic influence of NaOL in combination with surfactant NP-10 on the reverse flotation separation of dolomite from fluorapatite. Micro-flotation experiments revealed a 19.24% increase in dolomite recovery when adding 10% molar concentration of NP-10, resulting in a 20% reduction in collector dosage. Artificial mixed ore experiments demonstrated that NP-10 can enhance the selectivity of NaOL towards dolomite. The synergy between NP-10 and NaOL was found to reduce the molecular particle size of NaOL by 8%, improve its resistance to interference ions, and enhance its adsorption on the dolomite surface, consequently increasing dolomite's hydrophobicity, with negligible effects on fluorapatite. X-ray Photoelectron Spectroscopy (XPS) and adsorption capacity data indicated that both NaOL and NP-10 can adsorb Ca and Mg sites on the mineral surface, with NP-10 facilitating collector binding to Mg on the dolomite surface. Atomic Force Microscopy (AFM) analysis revealed that NP-10 did not impact the adsorption of NaOL on the surface of fluorapatite, but the combination of NaOL with NP-10 resulted in a denser and higher coverage on the dolomite surface compared to NaOL alone. This study provides a theoretical foundation for selecting surfactants to enhance the efficacy of fatty acids in mineral separation. [ABSTRACT FROM AUTHOR]

Hematite is commonly upgraded in China using a reverse anionic flotation process with starch as depressant for hematite, Ca2+ as activator and fatty acids as collector for quartz. The Anshan type of hematite is well known for its low grade, fine dissemination, difficulty in upgrading, and huge reserve in China. To investigate effects of nanobubbles and different reagents on the flotation process of this particular hematite, batch flotation tests were conducted with a mechanical flotation cell integrated with a cavitation device that generates nanobubbles under different process parameters including corn starch dosage, lime (CaO) dosage, collector dosage, and air flow rate through the nanobubble generator. Significant improvements in hematite flotation performance was achieved in the presence of nanobubble. The nanobubble flotation results and associated mechanisms are discussed based on up-to-date chemistry of hematite flotation and unique nanobubble characteristics. Unlabelled Image • A mechanical nanobubble flotation system was developed for reverse hematite flotation. • Nanobubbles were able to enhance reverse anionic flotation of hematite. • Different flotation reagents were investigated for their impacts on reverse nanobubble flotation. • Nanobubble flotation produced a concentrate of 68% grade and 84% recovery. • Nanobubble enhanced flotation mechanisms are presented. [ABSTRACT FROM AUTHOR]

It is necessary to exploit an easy and effective way to obtain flotation collector. In this paper, oleic acid was modified by oxidation reaction to obtain an excellent collector. The flotation performances of oleic acid and its oxidation products were systematically investigated and a novel collector ((E)-8,11- dihydroperoxyoctadec-9-enoic acid, EDEA) was obtained. Single mineral flotation tests results showed that EDEA had strong flotation power towards quartz at pH>11 and hardly floated hematite and magnetite at pH=8~13. The recovery of quartz could achieve 92.35% with 120 mg/L EDEA under the condition of pH=12 and dosage of CaCl2 60mg/L while the recovery was 62.44% with 120 mg/L oleic acid. Bench scale flotation tests results showed that EDEA had a preferable effect on separating quartz from iron ore especially at low flotation temperature (288K). The mechanism research revealed that EDEA attracted on quartz surface through electrostatic attraction and the neighboring EDEA molecules could form intermolecular hydrogen bonds which resulted in a closer alignment of EDEA on quartz surface. [ABSTRACT FROM AUTHOR]

Free carbon is the main impurity in boron carbide and has many side effects on the quality of boron carbide. In this study, reverse flotation was used for the first time to remove free carbon in boron carbide. The response surface methodology was utilized to optimize the reverse flotation factors, and the samples were analyzed by X‐ray diffraction, scanning electron microscope, laser particle size analyzer, and chemical analysis. The study results reveal that the main factors affecting the decarbonization ratio were slurry concentration, collector dosage, foaming agent dosage and pH value. Furthermore, the results also show that reverse flotation could be applied effectively to the removal of free carbon in boron carbide. Slurry concentration of 25.14%, collector dosage of 567.9 g/t, foaming agent dosage of 199.32 g/t and pH value of 8.4 were found to be the best conditions. Under the optimal conditions, the decarbonization ratio is 84.23%. Mass ratio of free carbon in boron carbide reduced from 2.98 to 0.47. [ABSTRACT FROM AUTHOR]

• Reverse flotation was introduced to process waste printed circuit boards. • Effects of various operational factors on flotation efficiency were investigated. • The separation mechanism of reverse flotation was clarified. • Reverse flotation presented feasible and environmental advantages. Reverse flotation was used to recover metal components from waste printed circuit boards (PCBs). The micro-morphology and chemical composition analysis of raw materials indicated that waste PCBs are mainly composed of glass fibers, ceramics and valuable metals. The effects of collector dosage and temperature on flotation efficiency were investigated and evaluated. The flotation results using various collectors showed that the efficient recovery of metal components could be achieved via reverse flotation with the diesel oil (DO) dosage of 370–1110 g/t, composite collector (CC) dosage of 370–740 g/t and laurylamine (LAM) dosage of 740 g/t, respectively. The suitable temperature should be controlled at around 20 °C for these collectors. The results also indicated that the selectivity of DO for nonmetal particles was stronger than that of CC and LAM. In summary, reverse flotation is a feasible and environmental approach for disposal of waste PCBs. [ABSTRACT FROM AUTHOR]

Molybdenum is an important alloy element for metallurgical industry. As the major mineral reserve for molybdenum, molybdenite (MoS 2) is commonly associated with talc. The flotation separation of talc and molybdenite is challenging due to their excellent inherent floatability. In this study, we innovatively used oxidant and inhibitor to perform reverse flotation of molybdenite and yeast infusion was evaluated as a potential depressant in the reverse flotation separation of molybdenite from talc. Flotation tests of single mineral samples and multi-mineral samples were carried out to evaluate the performance of yeast infusion and H 2 O 2 in flotation. And the results show that under the 100 mg/L H 2 O 2 , 100 mg/L yeast infusion treated molybdenite can be effectively separated from talc, the grade and recovery of Mo in the sink product were 42.8% and 80%. Contact angle measurement, X-ray photoelectron spectroscopy and zeta potential data indicated that the surface of molybdenite underwent slight oxidation after H 2 O 2 treatment. The hydrophilicity of molybdenite was also significantly enhanced. Results of infrared spectroscopy and adsorption tests demonstrated that H 2 O 2 enhanced yeast infusion adsorption on molybdenite. [Display omitted] [ABSTRACT FROM AUTHOR]

This study attempts to selectively inhibit hemimorphite flotation using sodium sulphide and uncover the mechanisms behind it. With the use of a fatty acid collector, the flotation test results showed that sodium sulphide had a strong inhibition performance on hemimorphite flotation while having no adverse impact on calcite and dolomite flotation, which were consistent with the contact angle measurement results. According to the results of attenuated total reflectance-Fourier transform infrared spectroscopy and adsorption proportion measurement of sodium oleate, sodium sulphide can inhibit sodium oleate binding on hemimorphite surfaces while having no effect on calcite and dolomite surfaces. The sulphide species exhibited an extremely high binding affinity for the hemimorphite surface but not for the surfaces of the calcium/magnesium-bearing gangue minerals, as demonstrated by the X-ray photoelectron spectroscopy measurements. Because of the strong sulphophile affinity of zinc, when the sodium sulphide concentration was sufficiently high, an interface boundary layer of a liquid solution with the remaining sulphide species formed on the hemimorphite surface, preventing sodium oleate from binding on the hemimorphite surfaces and thus selectively inhibiting the hemimorphite flotation. [Display omitted] • Na 2 S can strongly depress hemimorphite flotation but exhibits good selectivity towards calcite and dolomite. • Na 2 S can hinder sodium oleate binding on the hemimorphite surfaces without affecting calcite and dolomite surfaces. • Since sulphophile and oxyphile affinity differences, Na 2 S selectively inhibits the fatty acid flotation of hemimorphite. [ABSTRACT FROM AUTHOR]

In order to reveal the relationship between flotation behaviors of collectors and their structures, quantitative structure–activity relationship (QSAR) study about separation efficiency of quartz from hematite using amine collectors was performed. The genetic function approximation (GFA) algorithm was applied to generate the correlation models and model with acceptable R² and Rcv² (cross validated R-squared) correlation coefficients (R²=0.9666, Rcv²=0.9201) was developed. The model revealed that the Lowest Unoccupied Molecular Orbital (LUMO) energy of the molecule, the charge of nitrogen and the electronegativity of polar group were the major factors that affected the separation efficiency of collectors. The higher nitrogen charge, the larger electronegativity of polar group and the more positive of LUMO energy of amine collectors were, the higher separation efficiency would be. [ABSTRACT FROM AUTHOR]

• Addition of starches decreased the R f and R c of quartz or hematite particles. • At each experimental condition tested, R f was much higher than R c. • The decreases in R f and R c coincided with the increase in the aggregate size. • The R f and R c of Fe in the flotation of quartz-hematite mixture were measured. This paper reports the measured froth zone (R f) and collection zone (R c) recoveries in the flotation of pure quartz, pure hematite, and a quartz-hematite mixture with one of three corn starches with different mass ratios of amylose to amylopectin: waxy starch (0:100), normal starch (27:73), and Gelose 50 (50:50). The flotation tests were carried out at continuous mode using a three-product column at different pHs and starch concentrations with sodium oleate as collector and calcium chloride as activator. It was found that both R f and R c were significantly affected by pH and starch type and concentration. In the flotation of pure quartz or hematite, addition of each of the corn starches tested would decrease the R f and R c , with the effects following the order of waxy starch > normal starch > Gelose 50. The decreases in R f and R c coincided with the increase in the aggregate size caused by addition of these starches. Possible correlations between R f , solid flux at the pulp-froth interface and R c were examined. In the flotation of the quartz-hematite mixture, the changes in R f and R c of Fe caused by varying starch type and dosage were consistent with those in the flotation of pure hematite. [ABSTRACT FROM AUTHOR]

Abstract The depression of hematite in the reverse flotation system of oleate-starch-hematite was investigated at the atomic level by atomic force microscopy (AFM) combined with density functional theory (DFT). AFM imaging and cross-sectional imaging show that the adsorption configurations of oleate and starch on hematite were in shuttle and flake patterns, respectively, resulting in a greater adsorption thickness and adsorption area for starch than for oleate on the hematite surface. After functioned by starch, hematite was almost fully covered by starch so that there was no sufficient space for the adsorption of oleate. Corn starch was also detected aggregating fine hematite particles just like a flocculant. In the DFT study of the system, convergence tests were conducted to get the optimized hematite crystal geometry. The calculated interaction energies and Mulliken populations verified the favorable adsorption of oleate and starch on the hematite surface. Results indicated that covalent bonds formed between oleate and hematite, as well as between starch and hematite. However, in the oleate-starch-hematite system, the calculations showed that the distance between oleate and hematite in the presence of starch was too long to allow the adsorption of oleate. As for the water effect on the depression of hematite, the water molecules acted as a bridge between starch and the hematite surface by hydrogen bonds and were accompanied by chemical bonds between hematite surfaces and starch, which led to the depression of hematite. Therefore, in reverse flotation, oleate is hindered from adsorbing on the starch-covered hematite surface. The work presented here has profound implications for future studies of the depression of hematite, and may help solve the problem of screening and design of depressant of hematite. Highlights • AFM inspected the adsorption morphologies of starch and oleate on hematite. • DFT investigated the binding information of oleate and starch on hematite surface. • DFT calculations supported AFM experimental investigations. • Results revealed starch hindered the adsorption of oleate on hematite surface. [ABSTRACT FROM AUTHOR]

Abstract An effective collector plays a vital role in the reverse flotation of phosphate ore as well as sustainable production of phosphate fertilizer. Phosphate fertilizer is used to achieve the sustainable increase in the production of food. Phosphate ore is concentrated by reverse froth flotation and used as a raw material to produce phosphate fertilizer in industry. However, all the surfactants used in the phosphate ore reverse flotation process are conventional monomeric surfactants contain a single similar hydrophobic group in the molecule, which results in a low production efficiency and severe environmental contamination. In this work, a novel Gemini surfactant, N,N′-bis(dodecyldimethyl)-1,4-butane diammonium dibromide (BDBD) was prepared, and originally recommended as a collector for reverse froth flotation separation of silicoide from phosphate ore. The performance of BDBD was compared with the results acquired using its conventional monomeric surfactant dodecylamine hydrochloride (DAH). The bench-scale flotation results showed that BDBD had excellent collecting power for silicoide and significant selectivity against apatite at pH 9. Moreover, BDBD presented stronger desilication efficiency than DAH. Achieving the superior flotation performance (P 2 O 5 recovery increased by 2.41%, P 2 O 5 content increased by 0.26%, and SiO 2 content reduced by 2.52%), the dosage of Gemini type BDBD collector (100 g/t) is four times less than that of monomeric DAH collector (400 g/t). Therefore, this work provides a promising approach to the sustainable phosphate fertilizer production and to address global food security concerns. Graphical abstract Gemini surfactant as a collector for reverse froth flotation separation of silicoide from phosphate ore for sustainable phosphate fertilizer production. Image 10888 Highlights • A novel Gemini surfactant BDBD was introduced in phosphate fertilizer production. • BDBD exhibited superior selectivity for silicoide against apatite. • BDBD displayed superior flotation performances than conventional surfactant DAH. • Gemini is a promising collector for sustainable phosphate fertilizer production. [ABSTRACT FROM AUTHOR]

In order to improve the flotation performance of the coking coal particles, the flotation tests of the coking coal particles were conducted in the direct flotation, reserve flotation, and reverse-direct flotation processes. It was found that the concentrate ash content of coking coal particles was higher than 20%, which cannot be effectively reduced using the direct and reserve flotation processes. However, the flotation concentrate with the ash content of 12.53% can be obtained from the reverse-direct flotation process. In the reverse-direct flotation process, the surface hydrophobicity was reduced with the dextrin and 1-dodecylamine (DDA) addition at the reverse flotation process stage. For the addition of diesel collectors at the direct flotation process stage, the surface hydrophobicity of the coking coal samples was improved. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel low-foam viscous cationic collector DTDAB was synthesized. • DTDAB exhibited superior collector ability and selectivity than DTAB. • Insertion of hydroxyl could reduce interface tension and foam coalescence of collector. • Better selectivity was achieved by regulating the size of the polar group. Traditional cationic collectors generally exist some disadvantages, such as high foam viscosity and difficulty in defoaming, which worsening the flotation separation effect. Herein, a novel cationic collector-dodecyl trihydroxyethyl ammonium bromide (DTDAB) with low-foam viscous was synthesized to optimize the reverse flotation system of hematite ore, which was achieved by introducing three hydroxyethyl groups into the nitrogen atoms of dodecyl trimethyl ammonium bromide (DTAB). The analysis of foam collapse performance indicated that the introduction of hydroxyl groups into hydrophilic head groups of DTAB reduced the interface surface tension and bubble coalescence, which were consistent with the design expectations. Meanwhile, flotation behaviors were systematically studied, and the results showed that the concentrates with 63.89 % total iron (TFe) grade and 89.27 % total iron recovery was obtained at pH 6.81, when the concentration of DTDAB and starch was 20 mg/L and 5 mg/L, respectively. Besides, the possible flotation mechanism was further studied by means of contact angle, Atomic force microscope (AFM), Fourier transforming infrared spectra (FT-IR), X ray photoelectron spectroscopy (XPS), and Density functional theory (DFT) calculation. The results comfirmed that the adsorption between DTDAB and quartz was caused by electrostatic force and hydrogen bonding affinity. In conclusion, it can be confirmed that the novel cationic collector DTDAB with low-foam viscous has the potential for the hematite reverse flotation desilication. [ABSTRACT FROM AUTHOR]

A new type collector a-Bromolauric acid (α-BLA) had been proved to be an efficient collector for quartz flotation. However, the effects of α-BLA on the flotation behavior of iron minerals and quartziron separation had not been investigated. In this study, collector α-BLA was synthesized in the laboratory. The flotation behavior of quartz, hematite and magnetite under α-BLA reverse flotation system were investigated and the separation mechanism of quartz-irons was studied by contact angle, zeta-potential and infrared spectroscopy. The results showed that the optimum flotation pH was 11.5 for quartz, 6.45 for hematite and 6.97 for magnetite. The best α-BLA concentrations was 75 mg/dm³ for quartz flotation, 125 mg/dm³ for hematite and magnetite flotation. The activator CaCl2 had little effect on the flotation of hematite and magnetite, but the minimum dosage 50 mg/dm³ of activator CaCl2 was necessary for quartz flotation. On the contrary, starch had no effect on the flotation of quartz, while the recoveries of magnetite and hematite tended to be 0% as starch concentration more than 80 mg/dm³. The separation mechanism of quartz from iron minerals under α-BLA reverse flotation system was that the starch could be selectively adsorbed on the surface of hematite and magnetite in the form of strong hydrogen bond adsorption. However, the same adsorption of starch did not occur on the surface of quartz, so the α-BLA can be successfully adsorbed on the surface of activated quartz to make the quartz strongly hydrophobic, and then to be floated out. [ABSTRACT FROM AUTHOR]

Iron ore mineral processing techniques are constantly challenged with the emergence of complex gangue minerals such as amphiboles, pyroxenes and others. Magnetic separation technique that achieves good results for some richer iron ores cannot guarantee the same results for such complex ores. The flotation route allows upgrading the concentrate grade but is also challenged because of the depression of Fe–Mg–Al-bearing silicates due to the presence of metal ions on the mineral surface, which can form strong chemical complexes with starch molecules used as depressant of iron oxides. The adsorption mechanism of the principal depressants used in oxide ore flotation was investigated on chamosite (chlorite group), diopside (pyroxene group) and epidote. Since the adsorption of reagents is related to the mineral surface charge in physical adsorption systems, the electrokinetic properties of these minerals were also investigated to develop a common approach for complex iron ores processing by flotation when the gangue is presented by complex Fe-Mg-Al bearing silicates. [ABSTRACT FROM AUTHOR]

A new coated-reactive reverse flotation method based on the generation of CO 2 bubbles at a calcite surface in acidic solution was used to separate calcite from scheelite. The dissolution kinetics of coated and uncoated calcite were studied in sulfuric acid. The CO 2 bubbles generated on the uncoated calcite particle surface are enough to float the particle. However, most of these bubbles left the surface quickly, preventing calcite from floating. Here, a mixture of polyvinyl alcohol polymer and sodium dodecyl sulfonate was used to coat the mineral particles and form a stable membrane, resulting in the formation of a stable foam layer on the calcite surface. After the calcite is coated, the generated bubbles could be successfully captured on the calcite surface, and calcite particles could float to the air-water interface and remain there for more than one hour. Flotation tests indicated that a high-quality tungsten concentrate with a grade of more than 75% and a recovery of more than 99% could be achieved when the particle size was between 0.3 and 1.5 mm. The present results provide theoretical support for the development of a highly efficient flotation separation for carbonate minerals. [ABSTRACT FROM AUTHOR]

China has rich phosphate rock resources, but with their continuous depletion, the rich ore resources have become increasingly scarce, which makes the exploration of collophane more important. Medium- and low-grade phosphate rock cannot be utilized until their impurities have been removed through mineral processing. However, due to the similar physical and chemical properties of dolomite and phosphorus minerals, the separation of dolomite from phosphate rock is a challenge for the beneficiation of phosphate rock. In this study, a collector that can separate dolomite from apatite by selective flotation was combined. The agent, named D12, is a new anionic surfactant that was obtained by the phosphorylation of ether-based nonionic surfactants. In order to determine the performance of the D12 collector, it was used in a flotation test. In this process, the raw ore had phosphorus oxide (P2O5 ) grade of 22.06 percent and magnesium oxide (MgO) content of 5.94 percent. The grinding fineness of 0.074 mm was approximately 87.33 percent. For roughing, the dosages of sulfuric acid (H2SO4 ), citric acid and collector were 7 kg/t, 1.5 kg/t and 0.5 kg/t, respectively. In the cleaning stage, the dosages of H2SO4 and collector were 5 kg/t and 0.3 kg/t, respectively. Concentrate grade of 31.02 percent and recovery rate of 68.64 percent with an open circuit were obtained under these conditions. Moreover, concentrate grade of 30.31 percent and recovery rate of 84.47 percent with MgO content of 0.92 percent were obtained with closed-circuit beneficiation indexes. The agent, D12, is promising to be applied to the industrial practice of mineral processing of phosphate rock. [ABSTRACT FROM AUTHOR]

A novel surfactant 2-((2-(decyloxy)ethyl)amino)lauric acid (LDEA) – substituting 3-(decyloxy)propan-1-amine (DPA) on the α-carbon position of lauric acid was firstly synthesized and utilized as a collector for the flotation of quartz mineral at a relatively low temperature. The flotation performances and adsorption mechanisms of LDEA collector on quartz mineral surface were investigated by zeta potential measurements, Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS), in conjunction with the results of quartz micro-flotation tests. The flotation results showed that LDEA exhibited an excellent collecting performance on quartz mineral at a wide pulp pH range (about 6–11) with a low collector concentration 15.0 mg/L at a relatively low temperature 15 °C, where above 95.0% of the quartz mineral could be floated. Zeta potential measurements, FT-IR spectra, and XPS analyses reveal that the LDEA collector could be adsorbed on the surface of pure quartz in the forms of electrostatic and hydrogen bonding interactions at pulp pH 10.0. [ABSTRACT FROM AUTHOR]

Sulfuric acid (H 2 SO 4 ) is widely used as a depressant in the flotation of phosphorus minerals, usually in large dosages. This study used microflotation, flotation of the actual ore, X-ray photoelectron spectroscopy (XPS) analyses, reaction thermodynamic analyses and adsorption experiments, to examine the effect of citric acid (H 3 Cit) and a combined depressant (H 2 SO 4 /H 3 Cit) on collophanite ore flotation. H 2 SO 4 and H 3 Cit both exhibit selective depressive effects on apatite when they are used individually as depressants. When combined, the added H 3 Cit greatly reduced H 2 SO 4 dosages above 30% and produced better flotation results. Closed-circuit reverse flotation results for tests on the actual ore also confirmed this. Mechanism analyses demonstrated that H 3 Cit adsorbs onto apatite surface via a chemical chelating reaction with Ca 2+ . H 3 Cit is selectively and largely adsorbed onto apatite, thus selectively depressing it. Compared with SO 4 2– , the reactions of Cit 3− and Ca 2+ are thermodynamically favored at pH 5.5–13.0. Therefore H 3 Cit manifested a stronger inhibitive effect than H 2 SO 4 and significantly reduced the required H 2 SO 4 dosage. A rough economic evaluation suggests that the combined depressant exhibits economic advantages and shows potential for industrial application. [ABSTRACT FROM AUTHOR]

Compared to reverse cationic flotation, the advantages of reverse anionic flotation include relatively lower sensitivity to slimes and lower reagent cost. Besides, anionic collectors were found to have excellent capability of selectively separating an ultrafine magnetite ore. Addition of a small amount of cationic collector into the anionic collector as the collector mixture can improve the metallurgical results of removing silicates in reverse flotation. In this paper, NaOL and DDA were used for reverse flotation of the ultrafine magnetic concentrate. The separation performance of the collector mixture was investigated at different ratios of NaOL and DDA. The results showed that a better separation performance was obtained for the collector mixture than for NaOL alone. There was an optimal molar ratio between NaOL and DDA equal to 10:1. In the flotation system with the presence of the collector mixture, the good selectivity was found when starch was used as a depressor for magnetite and CaO was used as an activator for quartz. The influences of starch and CaO dosages on the separation performance of magnetite, quartz and chlorite had been investigated through micro-flotation tests. The infrared spectral analysis showed stretching vibration peaks of chemical adsorption of the collector mixture on the magnetite surface. The peaks were not present when starch was used as the depressor for magnetite. The closed flotation tests on the magnetic concentrate with the particle size of -25 µm were performed in the laboratory. The Fe concentrate assaying 64.52 % was obtained with Fe recovery of 80.66%, for the Fe content of feed equal to 52.98%. [ABSTRACT FROM AUTHOR]

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. [Display omitted] • Collector OL is less competitive than hydroxyl on the mineral surfaces. • Better selectivity of Ca(II) to the hydroxylated quartz than that of hematite. • Better selectivity of HM to the hydroxylated hematite than that of quartz. • OL can be effectively adsorbed on hydroxylated quartz in the presence of Ca(II). [ABSTRACT FROM AUTHOR]

In this study, a functional surfactant , 4-methoxy- (4′-(3-trimethylammoniumpropyloxy)-phenyl) azobenzene (PAQA), was synthesized and used as a collector to separate quartz from apatite by reverse flotation. UV spectrophotometry and 1H NMR were used to synthesize PAQA and its cis-trans isomerism successfully. The difference in floatability between quartz and apatite was investigated by pure mineral flotation experiments. The adsorption mechanism of PAQA onto quartz surface was investigated using contact angle, Zeta potential, and FT-IR spectroscopy. The results showed that PAQA could effectively separate quartz by physical adsorption in alkalescence (pH 8–9) without UV light. The different characteristics of PAQA on quartz before and after UV exposure were analyzed by QCM-D and AFM. It was observed that UV would degrade the interaction between surfactant and quartz, making it difficult to form a complete adsorption film, which is detrimental to the stability of flotation foam. [Display omitted] • The adsorption mechanism was studied by contact angle, Zeta potential, and FT-IR. • Different characteristics before and after UV were analyzed by QCM-D and AFM. • Quartz and apatite recovery was related to the amount of the PAQA adsorption. • UV light changes the surface hydrophobicity of quartz after PAQA adsorption. • The flotation defoaming problem is realized by using controlled foam change. [ABSTRACT FROM AUTHOR]

Removal of iron impurities in silica is one of the most important issues in the glass industry. The most noted impurities are surface coating and staining on silica particles; additionally, some cases of inclusions are observed. The prepared silica sample, for this research work, mostly was in the size range of 106-425 μm. Mineralogical studies indicated the existence of goethite, hematite, limonite and pyrite as the major iron impurities. The poor liberation degree of silica particles from clays encouraged the use of ultrasound irradiation to improve the efficiency of reverse flotation. The head sample contained 96.98% SiO2, 0.143% Fe2O3, 1.52% Al2O3, and 0.088% TiO2; Fe2O3 had to be reduced to below 0.04%. The reverse flotation tests were carried out with and without indirect ultrasound irradiation. The lowest Fe2O3 grade of the flotation yield was 0.058% and this was achieved using 2000 g/t of C4 collector with 15 min conditioning at neutral pH. C4 consisted of Aero 801, Aero 825, oleic acid and sodium oleate at equal dosage. As a result, a flowsheet was developed to include indirect ultrasound irradiation with reverse flotation and two stages of dry high intensity magnetic separation. In conclusion, the best product contained 98.43% SiO2, 0.034% Fe2O3, 0.90% Al2O3 and 0.051% TiO2. [ABSTRACT FROM AUTHOR]

[Display omitted] • A deep-sea silicate bacterium SiBY-2 was successfully screened out. • The process of SiBY-2 pretreatment-reverse flotation realizes the desilication and purification of magnesite tailings. • The erosion and flocculation of the SiBY-2 secretions play an important role in improving the separation. • The SiBY-2 pretreatment-reverse flotation process provides a new direction for the separation of magnesite tailings. According to the principle of cleaner production, strengthening the selectivity and separation effect of dodecylamine (DDA) as a conventional reverse flotation agent is an effective way to realize the re-enrichment of magnesite tailings, reduce the cost of agents, recover valuable elements, improve the quality of products and industrialize high value-added utilization. In this study, we designed the technology of microbial pretreatment-reverse flotation of magnesite tailings, and used the deep-sea silicate bacteria SiBY-2 to pretreat magnesite tailings, which enhanced the separation efficiency of magnesite from silicon bearing gangues in the reverse flotation process. The results show that the SiBY-2 enhances the desilication effect of magnesite tailings mainly by secreting organic acids, polysaccharides and proteins, and intensifies the interaction between silicon bearing gangues and the collectors (DDA). Compared with the conventional reverse flotation, the concentrate grade and recovery of the SiBY-2 pretreatment-reverse flotation process is increased by 2.04% and 5.93% respectively, while the utilization rate of DDA is reduced by 9.0%. It is estimated that the production cost of magnesite can be reduced by 900–1350 ¥/t, which achieves the purpose of clean production of magnesite high quality products. [ABSTRACT FROM AUTHOR]

In this paper, a surfactant, atlox4862 (formaldehyde condensate of methyl naphthalene sulfonic sodium salt) (MF), was introduced as a depressant for reverse flotation separation of sericite from graphite. Natural flake graphite has a strong hydrophobic property. After interacting with MF, the graphite became moderately hydrophilic. The flotation results showed that MF had a depressing ability for both sericite and graphite and that the flotation separation of sericite from graphite was attributed to the different declining levels of recovery between graphite and sericite with increased MF concentration. For a pulp pH of 8 and a MF concentration of 250 mg/L, the recovery rates of sericite and graphite were 89.7% and 11.3%, respectively. The results of the FTIR spectra and zeta potential measurements demonstrated that the interaction of MF with graphite and sericite is mainly through electrostatic attraction. MF was preferred to adsorb on the surface of graphite, decreasing its zeta potential and improving its hydrophilicity more than that of sericite. [ABSTRACT FROM AUTHOR]

Sedimentary phosphate occurs largely at Gafsa mining basin. Among these occurrences Jebel Alima (Redeyf region) is an open pit quarry. After extraction, raw phosphate requires several stages of treatments to become concentrated: crushing, grinding, scrubbing, sizing, attrition, de-sliming and flotation. The coarse reject, generated from the first step of ore processing, constitutes the main pollution source in the mining area around the washing plant. Since composition contains a host of environmentally hazardous chemical elements such as Cd, U, Pb…. The results of the chemical characterization also show that the raw sample can achieve P 2 O 5 grade of 13.52%. After 170 scrubbing tests, with 4 kg of solid waste for each test, the liberated fraction showed a content of 24.33% P 2 O 5 . After sieving, the fraction under 315 microns was recovered for flotation, whereas the fraction greater than 315 microns goes through grinding. 11 grinding tests were carried out taking into account the parameter variations (rotational speed, grinding time, solid concentration and load). The result of the optimum grinding is: Load: 7/1; speed: 60 tr / min; time: 5,5 min; Cs: 45%. The liberated fraction content is 20.24%. Before the reverse flotation, the product from scrubber outlet (fraction <315 microns) and the ground fraction (> 315 microns) were mixed. The feed material has a content of 22.44% P 2 O 5 . The beneficiation of waste reject was carried out by reverse flotation in acid medium with amines and esters. The content reached 28.16% P 2 O 5 with carbonation rate of 1.6. This content is very close to 29% (content of commercial phosphates). Therefore the coarse waste reject could be considered as potential reserves for the future. [ABSTRACT FROM AUTHOR]

Based on the analysis of occurrence states and properties of a calcareous–siliceous phosphorite, the effects of GZ 1 collector dosage, regulator dosage, pulp density and particles size distribution of sample on concentrate indexes were investigated by reverse flotation technology. The rare earth oxidize (REO) grade and recovery of concentrate were also analyzed in the work. Two-stage reverse flotation technology was applied for the beneficiation of a calcareous–siliceous phosphorite. Under the integrated optimal single factor conditions of GZ 1 collector 0.9 kg/t, phosphate regulator 14 kg/t and pulp density 35 wt.%, mass fraction of particles size of − 74 μm of 85 wt.%, flotation time of 11 min and flotation pH of 5.5, the P 2 O 5 grade increases from 14.64 wt.% in raw ore to 26.82 wt.% in the concentrate, and the recovery is 72.09 wt.%, while REO grade increases from 0.08 wt.% in the raw ore to 0.175 wt.% in the concentrate, and the recovery is 86.08 wt.%. [ABSTRACT FROM AUTHOR]

Beneficiation of manganese ores has been conducted around the world by circuits composed basically of crushing, screening and spiral classifier. Therefore, solely the coarse size fractions (and commonly the richest) are actually recovered: "lump" (-75+9mm) and "sinter feed" (-9+0.15mm). In the industrial plant which processes the ore from the Azul Mine-PA, the overflow of the spiral classifier (- 0.15mm) is disposed of in a tailings dam because it bears a low Mn content (<10%) and high kaolinite content (70%). This paper reports the findings of a process development conducted on laboratory scale with the aim of concentrating Mn-bearing minerals from the tailings of the Azul Mine-PA (7% of Mn and 70% of kaolinite). The process is composed of desliming (-10µm), followed by reverse cationic flotation of kaolinite (rougher, scavenger) at pH~5. Results indicate that the reverse cationic flotation in the acid medium, when utilizing amide amine as collector and in the presence of a silicate activator and a dispersing agent could be a possible route for the concentration of tailings that had previously been deslimed at 10µm. The results yielded a mass recovery of 18%, a metallurgical recovery of 50% and a 32% Mn concentrate which may be mixed with current high grade products, increasing the overall recovery of the plant. [ABSTRACT FROM AUTHOR]