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The grinding process plays a crucial role in the floatability of mineral. The present study proposes a scheme to assist in the flotation separation of galena and pyrite by optimizing the choice of grinding media. The effects of grinding media (cast iron balls, steel balls containing 18% chromium, and steel balls containing 12% chromium) on the pulp properties and hydrophilicity of galena and pyrite were evaluated using grinding tests, micro-flotation tests, X-ray photoelectron spectroscopy, and adsorption capacity analyses. The results showed significant differences in the pH, potential, and dissolved oxygen content of the galena or pyrite pulp with different grinding media, resulting in significant differences in the flotation behavior of galena and pyrite. The use of cast iron balls in the grinding process was more favorable for the flotation separation of galena and pyrite. The pyrite surfaces adsorbed less butyl xanthate when cast iron balls were used as grinding media due to the presence of more hydrophilic hydroxyl iron. Therefore, cast iron balls as grinding media are favorable for broadening the surface hydrophilic differences between galena and pyrite. [ABSTRACT FROM AUTHOR]

The gold contained in copper ores is an important resource for the gold industry. In some cases, elemental gold is present and can be recovered by selective flotation. It has been reported that the gold grade and recovery can be increased, without sacrificing the copper recovery, by replacing AERO 3477 (diisobutyl dithiophosphate (DTP)) with AERO 7249 (mixture of diisobutyl monothiophosphate (MTP) and diisobutyl dithiophosphate (DTP)) as the main collector. The fundamental understanding of the improvement in selectivity with the addition of MTP in the flotation of elemental gold from pyrite is limited and is the subject of this paper. In this regard, the hydrophobicity and selectivity of DTP and MTP in the flotation of pyrite and gold are compared and discussed. Density functional theory (DFT) was used to examine the electron density, reactivity, highest occupied molecular orbital (HOMO), and lowest unoccupied molecular orbital (LUMO) of the MTP and DTP collectors. The interaction energies for the adsorption of MTP and DTP from fresh pyrite, oxidized pyrite and gold surfaces were calculated and discussed with respect to the experimental results reported in the literature. Molecular dynamics simulation (MDS) was used to examine the adsorption state of MTP and DTP on the pyrite (100) and Au (111) surfaces. [ABSTRACT FROM AUTHOR]

The recovery of scheelite from calcium-bearing carbonate ores by foam flotation is challenging due to its low separation efficiency. This study investigated the effect of pentasodium diethylenetriaminepentaacetate (PD) on the surface properties of scheelite and fluorite. For this purpose, we performed micro-flotation tests and carried out zeta potential measurements, as well as Fourier transform infrared (FT-IR) and X-ray photoelectron (XPS) spectroscopic measurements, in order to analyze the surface properties of these minerals. The addition of PD as a novel depressor significantly improved the effect of fluorite and sodium oleate (NaOl) on the flotation-based scheelite recovery and separation from fluorite. PD was spontaneously adsorbed onto fluorite through electrostatic and chemical adsorption. By contrast, PD did not appear on the scheelite because of the reaction conditions, surface site, and steric hindrance. X-ray photoelectron spectroscopy measurements and a solution chemistry analysis were used for the determination of the PD-selective adsorption mechanism and key factors derived from multi-layer adsorption onto fluorite, which completely hindered that of NaOl. [ABSTRACT FROM AUTHOR]

Lead(II)–benzohydroxamic acid (Pb–BHA) complex collectors perform well with respect to scheelite flotation, and, due to their structure, they are widely used for industrial purposes. This paper examines the controversial issue of whether "O, O" five-membered ring or "N, O" four-membered ring complexes are formed when BHA coordinates with Pb ions, with their structure being comprehensively studied from the aspect of colloid and interface science. The configurations of Pb–BHA complexes are examined in a solution and on a mineral surface with experimental and computational methods. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) revealed that the five-membered ring is the dominant form of Pb–BHA complexes in a solution, whereas four-membered ring complexes are the stronger electron acceptor of the two. Moreover, XPS and time-of-flight secondary ion mass spectrometry (TOF-SIMS) confirmed that the four-membered ring complexes are stable with respect to being adsorbed on the scheelite surface. Therefore, although the four-membered ring is not as stable as the five-membered ring in a solution, it offers advantages with respect to adsorption on an electron-rich mineral surface during short-flotation processes. [ABSTRACT FROM AUTHOR]

Apatite (Ca10(PO4)6F2) is the most important phosphate mineral, and flotation is the main beneficiation method to separate apatite from its major gangue mineral calcite (CaCO3). Till date, fatty acids and their salts have been widely used as collectors in the apatite/calcite flotation separation due to their low cost and strong collecting ability, but their selectivity is limited. Therefore, screening or designing a selective collector becomes the key to the efficient separation. In this work, an attempt was made to utilize benzohydroxamic acid (BHA) as the collector for the selective separation of apatite from calcite without any depressant. The single and mixed binary mineral flotation experimental results prove the excellent selectivity of BHA in the apatite/calcite flotation separation. Zeta potential measurement results indicate a greater affinity of BHA on the apatite surface than calcite, which is also confirmed by the higher adsorption energy of BHA on the apatite surface based on the first-principle density functional theory calculations. The X-ray photoelectron spectroscopy analysis shows that the selective chemisorption of BHA on apatite over calcite is due to the stronger reactivity and the higher density of Ca2+ ion on the apatite surface than calcite. This work shows that surfactants of hydroxamic acid type can be an ideal collector for phosphate mineral flotation. [ABSTRACT FROM AUTHOR]

Pyrite depression in copper ore flotation often requires large doses of inorganic depressants that lead to high toxicity, high costs, and low selectivity. Thus, this study offers a novel pyrite depressant, polyglutamic acid (PGA), in the selective flotation of chalcopyrite with xanthate as a collector. The flotation and adsorption mechanism on chalcopyrite and pyrite were systematically studied using a series of flotation tests, zeta potential measurements, adsorption analysis, infrared spectral (IR) analysis, and X-ray photoelectron spectroscopy (XPS) analysis. The addition of PGA depressed the flotation of pyrite more strongly than chalcopyrite in the wide pH range of 8–12. In the presence of PGA, selective separation between the two minerals was achieved at pH 9, and the recovery of chalcopyrite was over 85% and that of pyrite was less than 20%. All of the surface analysis techniques indicated that PGA interacted differently with the two minerals and the surface of pyrite adsorbed a much greater amount of PGA than that of chalcopyrite. Prior addition of PGA significantly reduced the adsorption of the collector on the pyrite surface and thus depressed its flotation. However, the significant adsorption of the collector and its oxidation to dixanthogen on the chalcopyrite surface caused its improved flotation even in the presence of PGA. Therefore, PGA, which is a non-hazardous, biodegradable, and renewable reagent, could be used as an alternative pyrite depressant in Cu–Fe conventional flotation circuits. • PGA achieves improved selective separation of chalcopyrite (Clp) and pyrite (Pyr). • Polyglutamic acid (PGA) is a nontoxic and degradable depressant of Pyr flotation. • Clp adsorbs much greater amount of xanthate than Pyr in the presence of PGA. • PGA could be an alternative depressant in Cu–Fe conventional flotation circuits. [ABSTRACT FROM AUTHOR]

In this study, the effect of phytic acid (PA) on the surface properties of scheelite and fluorite was systematically investigated. PA was spontaneously adsorbed onto fluorite through electrostatic and chemical adsorption. By contrast, PA did not appear on the scheelite due to the reaction conditions, surface site, and steric hindrance. XPS measurements were utilized together with a solution chemistry analysis to understand better both the PA selective adsorption mechanism and the key factors derived from multi-layer adsorption onto fluorite, which was found to hinder completely that of NaOl. [ABSTRACT FROM AUTHOR]

Highlights • TCSS achieves improved selective separation of chalcopyrite (Clp) from pyrite (Py). • Tricarboxylate sodium starch (TCSS) is a biodegradable depressant of Py flotation. • Clp adsorbs more xanthate collector than Py in the presence of TCSS depressant. Abstract In the flotation of copper sulfides, pyrite is often activated by Cu2+ ions dissolved from copper-bearing minerals in alkaline media (pH ˃ 9), which results in pyrite entering the copper concentrate. To reduce the floatability of pyrite, we designed a novel functionally modified biopolymer, tricarboxylate sodium starch (TCSS), that showed superior depression selectivity towards pyrite in low pH solutions when employed in Cu–Fe flotation separation in the presence of sodium butyl xanthate (SBX) as a collector. TCSS depressed the floatability of pyrite more strongly than that of chalcopyrite in single mineral flotation in the pH range 4–6. The most selective separation was achieved at pH ∼ 6; the recovery of Cu in the concentrate was over 77%, and the grade was improved to 24.50% compared to the initial feed grade of 12.50%. Surface characterization analyses, including zeta potential, X-ray photoelectron spectroscopy (XPS) analysis, and Fourier transform infrared (FTIR) spectroscopy, confirmed the different degrees of interaction of TCSS with the two minerals. TCSS was adsorbed on the pyrite surface, possibly via a chemisorption mechanism, as reflected in the FTIR and XPS analyses. The adsorption of TCSS passivated the pyrite surface, which inhibited the adsorption and oxidation of the collector. On the other hand, the adsorption and oxidation of the collector on chalcopyrite surface were effective even in the presence of TCSS, attesting to the weak interactions between chalcopyrite and TCSS. [ABSTRACT FROM AUTHOR]

Highlights • The three polycarboxylic acids effectively inhibit calcite flotation. • The inhibition abilities decrease in the order of PASP > HPMA > PESA. • The depressant prevents the adsorption of sodium oleate on calcite surface. • PASP exhibits best selectivity in the flotation separation of fluorite from calcite. Abstract As a common gangue mineral, the inhibition of calcite is very important to enrich the valuable minerals by flotation. With the increasing complexity of mineral properties and higher requirements for environmental protection, developing a newly eco-friendly depressant for calcite flotation is necessary. In this study, the effects of polyaspartic acid (PASP), polyepoxysuccinic acid (PESA), and hydrolytic polymaleic anhydride (HPMA) on the flotation performance of calcite using sodium oleate as the collector were investigated through flotation experiments. The results showed that all the three depressants exhibited strong inhibition to calcite, and the inhibition capabilities decreased in the order of PASP > HPMA > PESA. The results of zeta potential measurement, contact angle measurement and X-ray photoelectron spectroscopy indicated that the adsorption of sodium oleate on calcite surface was greatly decreased as the addition of the depressant. To investigate the inhibition selectivity, three depressants were used in fluorite flotation, and the results suggested that sodium oleate could still adsorb on fluorite surface in the presence of PASP. The flotation separation of fluorite from calcite could be therefore realized with PASP on the basis of the best selectivity among the three depressants. [ABSTRACT FROM AUTHOR]

Highlights • Flotation has been typically used to obtain high-grade feldspar. • Mixed cationic/anionic collectors represent a promising method for feldspar flotation. • Future research needs on the feldspar beneficiation are discussed. Abstract Feldspar is a valuable raw material in the manufacture of glass, ceramic, fillers, enamel frits, and welding electrodes. Feldspar is the single most abundant mineral in the earth crust and is generally associated with other silicate, titanium, and iron minerals. As a result, beneficiation of feldspar is necessary to obtain high-grade materials for industrial use. However, the beneficiation of feldspar ores from other silicate gangues is very difficult owing to their similarities in physical–chemical properties. Hydrofluoric acid (HF), which is the main regulator used in the flotation of feldspar, may cause serious environmental and health-related problems. Therefore, to satisfy the quality of advanced materials, the concentration of feldspar using clean and efficient methods remains a formidable challenge. This paper reviews the beneficiation technology and mechanism of feldspar proposed in the literature to identify the important parameters. This review indicates that crystal structure, monovalent salts, flotation reagents, and particle size distribution are important factors in the process. Environmentally-friendly principle and economic viability of various methods are discussed, and potential technologies are suggested. Mixed cationic/anionic collectors appear to be a promising method for feldspar flotation. Moreover, the combination of gravity and flotation shows great potential in feldspar beneficiation. Various approaches for the selective flotation of feldspar and perspectives for further investigation are proposed. [ABSTRACT FROM AUTHOR]

In previous studies, by regulating the Pb/BHA ratio and pH, lead complexes of benzohydroxamic acid (Pb-BHA) have been proven to be selective for the separation of scheelite from calcium minerals. In this study, sodium silicate (Na 2 SiO 3 ) and Al-Na 2 SiO 3 polymer were used as depressants for the further separation of scheelite from calcite. Flotation results indicated that both scheelite and calcite were depressed by Na 2 SiO 3 , while Al-Na 2 SiO 3 polymer gave good selectivity. The depressing ability of Na 2 SiO 3 for calcite was significantly improved due to the formation of some Al-Na 2 SiO 3 species with aluminum ions, while the reverse was true for scheelite. Zeta potential results indicated that both colloidal Na 2 SiO 3 and Al-Na 2 SiO 3 particles were negatively charged and difficult to adsorb on the negative scheelite surface through electrostatic attraction, especially for Al-Na 2 SiO 3. X-ray photoelectron spectroscopy analysis results showed that the Al-Na 2 SiO 3 adsorbed amount on the scheelite surface was less than the Na 2 SiO 3 adsorbed amount, while the reverse was true on the calcite surface. Binding energy analysis results indicated that calcium cations of scheelite and calcite surfaces could bond to oxygen atoms of Na 2 SiO 3 /Al-Na 2 SiO 3 through chemisorption. However, compared with Na 2 SiO 3 , Al-Na 2 SiO 3 showed weaker chemisorption on the scheelite surface, but adsorbed more powerfully onto the calcite surface. Therefore, Al-Na 2 SiO 3 showed excellent selectivity for scheelite and calcite, which has been successfully applied at the Shizhuyuan mine. [ABSTRACT FROM AUTHOR]

This research demonstrates an effective application of etidronic acid to improve the scheelite flotation efficiency and reduce the consumptions of energy and reagents. The cleaning recovery is significantly increased by 7%, and the cleaning cost is reduced by 17% accompanied with the efficient improvement of roughing grade from 1.22% to 1.68% compared with that in previous month. The depression abilities of etidronic acid, normal water glass, and acidified water glass for the scheelite roughing flotation are studied using laboratory-scale experiments. Etidronic acid shows an improved selective performance in improving the roughing grade. This performance is further verified by industrial test. The use of etidronic acid in the roughing circuit improves the product grade from 24.66% to 28.26%. The daily product output is also increases by 1.54 t. Economic evaluation results indicate that the heating cost is reduced by 28%, and the water glass consumption is decreased by 14%. An increased product profit of $1,248,000 and a reduced cost of $20,841 are also obtained. [ABSTRACT FROM AUTHOR]

To improve the floatability of tungsten minerals, lead ions (lead nitrate) were used to modify the surface properties of the minerals and benzohydroxamic acid (BHA) was used as a collector in the flotation system. Pb 2+ -BHA complexes are inevitably present in this process and the role of it is unclear. This investigation is going to describe a new approach and the mechanism of catalyzing BHA adsorption onto scheelite by lead ions. Chemical speciation, zeta potential, FTIR, and XPS studies were conducted to establish the important role of lead ions. Indeed, Pb 2+ -BHA complexes were shown to be the active species responsible for flotation. The speciation and zeta potential results showed the presence of the adsorbed Pb 2+ -BHA complexes on the scheelite. The XPS results for atomic composition and binding energies confirmed Pb 2+ -BHA species adsorbed on the scheelite surface, which contributed to more adsorption of BHA. The new method would increase the recovery of scheelite, simplify the flowsheet and reduce the processing cost. [ABSTRACT FROM AUTHOR]

Copper and lead are two important and widely used metals in industry. Chalcopyrite (CuFeS2) is associated with galena (PbS) in ore, and it has been a research hotspot in separating galena from chalcopyrite by flotation. In this study, the flotation behaviors of chalcopyrite and galena were studied through flotation tests, adsorption measurements, solution chemistry calculation, Fourier transform infrared spectroscopy (FTIR) and molecular dynamics (MD) simulations. The results show that the floatability of chalcopyrite is better than that of galena in the presence of O-isopropyl-N-ethyl thionocarbamate (IPETC), and the recovery difference between chalcopyrite and galena is about 20% when IPETC is 7 x 10-4 mol/L at pH 9.5, while the floatability difference between the two minerals is significant. Competitive adsorption of OH- and IPETC on mineral surfaces leads to lower floatability of galena than that of chalcopyrite. IPETC is able to remove the hydration layer on mineral surfaces and then adsorb on active sites. The floatability of minerals is enhanced with the increase of their hydrophobicity. This study provides a reference to separate galena from chalcopyrite. [ABSTRACT FROM AUTHOR]

The adsorption behaviors and the activation mechanism of calcium ions (Ca 2+ ) on sericite surface have been investigated by Zeta potential measurements, Fourier transform infrared spectroscopy (FT-IR), Micro–flotation tests and First principle calculations. Zeta potential tests results show that the sericite surface potential increases due to the adsorption of calcium ions on the surface. Micro-flotation tests demonstrate that sericite recovery remarkably rise by 10% due to the calcium ions activation on sericite surface. However, the characteristic adsorption bands of calcium oleate do not appear in the FT-IR spectrum, suggesting that oleate ions just physically adsorb on the sericite surface. The first principle calculations based on the density functional theory (DFT) further reveals the microscopic adsorption mechanism of calcium ions on the sericite surface before and after hydration. [ABSTRACT FROM AUTHOR]

Lead ions (lead nitrate) were introduced to modify the surface properties of tungsten minerals, effectively improving the floatability, with benzohydroxamic acid (BHA) serving as the collector. Flotation tests indicated that Pb-BHA complexes were the active species responsible for flotation of the tungsten minerals. The developed Pb-BHA complexes and the novel flotation process effectively increased the recovery of scheelite and wolframite, simplified the technological process, and led to reduced costs. Fourier transform infrared spectra data showed the presence of adsorbed Pb-BHA complexes on the surface of the minerals. The characteristic peaks of BHA shifted by a considerable extent, indicating that chemical adsorption plays an important role in the flotation process. Zeta potential results confirmed physical adsorption of the positively charged Pb-BHA complexes on the mineral surfaces. The synergistic effect between chemical and physical adsorption facilitated the maximum flotation recovery of scheelite and wolframite. [ABSTRACT FROM AUTHOR]

As one of the most important auxiliary collectors, alcohol is commonly used together with amine collectors in the flotation of oxide minerals to improve their grade and recovery. As important factors in the flotation process, the surface activity and self-aggregation behavior of DDA/alcohol mixtures at the water/air interface were investigated using molecular dynamics simulation and surface tension measurement. Four alcohol surfactants with different chain lengths, octanol (OCT), decanol (DEC), dodecanol (DOD), and tetradecanol (TER), were chosen to investigate the influence of the alkyl chain length on the surface activity and aggregation behavior. Molecular dynamics simulations show that DDA/alcohol mixtures exhibit strong synergism at the air/water interface and form compact packed hydrophobic films, compared to pure DDA at the same concentration. The mixtures appear to aggregate more easily due to the weakening of the electrostatic DDA headgroup repulsion. Among these four alcohols with different chain lengths, DDA/DOD and DDA/TER mixtures show good compatibility between surfactants tails, therefore, they can form the most tightly packed films at the air/water interface. Our simulation is in good agreement with previously reported data and surface tension results from this work. Therefore, this research on the molecular scale provides vital information on the surface behaviors of mixed surfactants at the air/water interface. [ABSTRACT FROM AUTHOR]

Benzohydroxamic acid (BHA) has been widely used as the collector for cassiterite flotation, whereas low collecting ability of BHA need to be improved. It is shown through flotation that BHA exhibits weak collecting capacity to cassiterite even in the case of using lead nitrate as the activator, but the superior floatation performances of lead(II)–BHA complexes is observed. The adsorption isotherms of BHA onto cassiterite reveal a higher adsorption density around pH 9 using lead(II)–BHA complexes as the collector. The complexation of lead(II) by BHA has been studied by differential pulse voltammetry. In weak alkaline solution, [Pb(HL)] + and [Pb(OH)(HL)] species with significantly collecting power are well predominant. Zeta potential studies demonstrate a stronger affinity to the mineral surface of Pb 2+ /Pb(OH) + –BHA complexes. XPS and FTIR studies indicate that chemisorption with the similar formation of Sn–O–Pb bond is the main interaction between the two kinds of collector and cassiterite. [ABSTRACT FROM AUTHOR]

The similar flotability of scheelite, fluorite, and calcite resulted in the difficult separation by flotation. This work revealed the effect of water glass on the flotation of scheelite by FTIR and the wettability change of the usual cleavage plane, and proved that water glass inevitably influenced the flotation of tungsten minerals to a large extent in traditional fatty acid flotation process. A new collector, lead complexes of benzohydroxamic acid, was found to be selective for the separation of scheelite and calcium minerals with little water glass. Hence a novel flotation process was developed for the recovery of tungsten minerals in Shizhuyuan Mine in China. Normal temperature flotation of tungsten minerals was developed to instead of the classical “Petrov's process” for scheelite-calcite-fluorite type ores. Compared with the traditional process, the recovery was improved by almost 10% and the grade of scheelite concentrate was above 55%. The disappearance or decreasing of water glass contributed to improving the recovery of tungsten and the circulation of water and reagents. [ABSTRACT FROM AUTHOR]

Highlights • Calcite is more difficult to be depressed in the mixed concentrate of fluorite and calcite. • Depressing effect of depressant on calcite was significantly enhance by acid. • The mixture of acid and depressants can depress calcite better. • Surface dissolution is the key factor in depressing of calcite by acidizing depressants. Abstract In this study, the effects of reagent addition order on the flotation behavior of calcite and fluorite, as well as the influence of acid on the floatation behavior of the calcite, were investigated. Results showed that when the calcite surface had adsorbed the collector, the depression of calcite became increasingly difficult. The presence of acid significantly enhanced the selective depressing effect of depressants on calcite. Actual ore flotation and artificial mixed ore flotation experiments demonstrated that the addition of acid can significantly reduce the calcite content in the concentrate. This phenomenon can be explained by the exposure of the new calcite surface due to the surface dissolution, which facilitated the reaction of calcite with the depressor. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The beneficial effects of the synergy between two reagents were realized long time ago. The purpose of using a mixture of collectors is to increase both the recovery and selectivity. In this work, sodium iso-amylxanthate (SIAX) and its isomeride (Y89), having different molecular structures, were used. The separation performance of these collectors were investigated at ratio varies of SIAX and Y89. The results showed that a better recovery of auriferous pyrite was observed with collector mixture comparing to use collector alone. There exist an optimal mass ratio between SIAX and Y89, and it is 1:2. The adsorption measurements of collector mixture and single collector were investigated at pH = 9, indicated that adsorption density of collector on auriferous pyrite surface was improved when collector mixture was used. Infrared spectral analysis suggested stretching vibration peaks from chemical adsorption were increased with using collector mixture. At an optimal mass ratio 1:2 of SIAX:Y89, an Au concentrate assaying 12.79 g/t was produced with an Au recovery of 84.24% from a feed containing only 3.44 g/t Au after one roughing stage. The advantage of this collector mixture can improve the recovery of auriferous pyrite at the same collector consumption, and this collector mixture has great potential for industrial application. [ABSTRACT FROM AUTHOR]

The selectivity in flotation separation of spodumene from other pegmatic aluminosilicates such as feldspar and mica, using a single fatty acid anionic collector, is found to be very difficult. It is attributed to the same surface Al site for interaction with fatty acid. In this study, a collector mixture of sodium oleate (NaOL) and dodecyl trimethyl ammonium chloride (DTAC) demonstrates a high selectivity for the flotation of spodumene from feldspar. The influences of important factors such as molar ratio of the mixed collectors, dosages of calcium chloride, sodium hydroxide and sodium carbonate, and pulp temperature on spodumene and feldspar flotation using the mixed collectors have been investigated through micro-flotation tests. The optimum molar ratio of NaOL and DTAC is found to be 9:1. Sodium hydroxide has to be used as a pH regulator. Without the use of depressants, no selectivity is observed as the flotation of spodumene and feldspar are activated by Ca 2+ . Sodium carbonate must be used as depressant of feldspar. A comparison of the flotation for a lithium pegmatite ore using mixed fatty acid soaps and mixed anionic/cationic collectors (NaOL/DTAC) was carried out by the batch flotation tests. The results indicated that NaOL/DTAC decrease collector consumption by two-thirds. The recovery and grade of Li 2 O concentrates increase by 4.93% and 0.31%, respectively. [ABSTRACT FROM AUTHOR]

The synergistic effect of the mixed cationic dodecyl amine-hydrochloride (DDA) and anionic collector sodium oleate (NaOL) at the air/water interface was investigated by the surface tension measurements. Various physicochemical properties such as surface activity parameters (CMC, γ CMC , Γ max , A min ), the micellar and interfacial compositions ( X 1 m , X 1 σ ) and interaction parameters (β m , β σ ) were evaluated according to the theory of regular solutions. It is observed that the mixed DDA/NaOL at α DDA = 0.5 exhibit a maximum synergistic interactions at the air/water interface. The flotation and adsorption of DDA/NaOL at the solid–liquid interface was investigated by flotation tests with muscovite, contact angle measurements and adsorption measurements. The flotation results indicate that the recovery of muscovite could be achieved a maximum value (98.45%) by the mixed DDA/NaOL at α DDA = 0.25 at pH 7.0. Contact angle measurements further confirm that the DDA/NaOL exhibit more superior hydrophobicity and collecting property than the individual DDA and NaOL. And a more pronounced synergistic effect of DDA/NaOL on muscovite surface at α DDA = 0.25 is observed, which could be attributed to a favourable arrangement of adsorbing species. The adsorption results show that the individual cationic DDA can be adsorbed strongly onto the muscovite, but no significant adsorption of anionic NaOL can be detected. However, in the mixed systems, the adsorption amounts of both DDA and NaOL are enhanced due to co-adsorption. It is proved that there is also a remarkable synergistic effect of mixed DDA/NaOL collectors at the solid–liquid interface. [ABSTRACT FROM AUTHOR]

The performance of the mixed dodecylamine chloride (DDA)/octanol (OCT) surfactants on muscovite flotation was investigated using flotation tests, and their adsorption mechanisms on muscovite and air/water interface were clarified using contact angle measurement, surface tension and molecular dynamics (MD) simulations. The flotation results indicate that the recovery of muscovite rapidly decreases when the pH increases in the presence of only DDA, whereas the recovery of muscovite is high (> 77%) over a wide range of pH in the presence of the mixed DDA/OCT surfactants with a ratio of 2/1. Contact angle measurements further confirm that the mixture displays a stronger collecting power than DDA and is a superior collector for the muscovite flotation. The surface tensions of DDA, OCT and their mixture indicate that the mixture is more efficient than DDA at decreasing the air–water interfacial tension and exhibits much better surface activities. MD simulations show that the mixture interacts with the muscovite mainly through electrostatic attraction and hydrogen-bonding. DDA ion is dominant in the interaction between the mixture and muscovite. OCT molecules are co-adsorbed onto the muscovite through the hydrogen-bond interaction and hydrophobic association with DDA ions. Compared with DDA, a well-compacted monolayer is formed on the muscovite surface in the presence of mixed surfactants, indicating a much stronger hydrophobic character of muscovite. [ABSTRACT FROM AUTHOR]

Comparative studies of flotation of oleate on diaspore and kaolinite in different particle size fractions (0.075–0.038 mm, 0.038–0.01 mm, 0–0.01 mm) are presented to investigate the influences of particle size. The flotation results show that the kaolinite recovery increases with a decrease in particle size, while the case of diaspore is the opposite. Chemisorptions of anionic oleate collector on the surface Al sites of the negatively charged diaspore and kaolinite are confirmed by zeta potential and FTIR measurements. Anisotropic surface broken bond densities are calculated based on surface crystal chemistry to characterize anisotropic wettability of mineral crystals. The increasing order of broken bond densities ( D b ) and hydrophobicity for different crystal planes of diaspore and kaolinite correlate well with increasing the number of broken Al O bonds. The anisotropic adsorption of oleate on different crystal planes of diaspore and kaolinite are studied in terms of interaction energies computed by molecular dynamics (MD) simulations. The oleate is adsorbed more readily on (0 1 0) than (0 0 1) for diaspore. As for kaolinite, the oleate adsorption is considerably less on (0 0 1) as compared to (1 10 ). The conclusions drawn from purely theoretical computations are in good agreement with our experimental contact angle results. [ABSTRACT FROM AUTHOR]

Abstract: The flotation behaviors of kaolinite and diaspore were investigated using N,N-dipropyl dodecyl amine (PN). Maximum recoveries of kaolinite and diaspore were about 90% and 50%, respectively. Both recoveries of kaolinite and diaspore increased with the increasing dosage of PN. On the basis of the zeta potential and FT-IR spectra, the ionization of surface hydroxyl and the isomorphic exchange of surface ions account for the charging mechanisms of surfaces of kaolinite and diaspore. The adsorption mechanism of PN on the surface of two minerals was mainly electrostatic. After reacting with PN, the zeta potential of kaolinite and diaspore both increased, and comparing with the original zeta potentials, potential of kaolinite increased much more than that of diaspore, this can explain why recovery of kaolinite is higher than that of diaspore. [Copyright &y& Elsevier]

Abstract: The flotation behavior of kaolinite was investigated using a series of tertiary amines (DRN, DEN, DPN and DBN). Maximum recoveries of kaolinite were 93%, 88% and 84% for DEN, DPN and DRN, respectively. The recovery for DBN was very low. On the basis of the Zeta potential and FT-IR spectra, the ionization of surface hydroxyl and the isomorphic exchange of surface ions accounts for the charging mechanisms of the kaolinite surface. The adsorption mechanism of tertiary amines onto the kaolinite surface was mainly electrostatic. We determined that the IEP of kaolinite increased from 3.4 to higher values after the interaction of kaolinite with the four tertiary amines. FT-IR spectra of kaolinite changed to include sharp peaks of tertiary amines. Inductive electronic effects and space-steric effects of –CH3, –C2H5, –C3H7 and –C7H7 bound to the N atom result in different collecting powers for the four tertiary amines. [Copyright &y& Elsevier]

Abstract: The electrokinetics and flotation behavior of kaolinite have been investigated through flotation experiments, zeta potential measurements, and FTIR spectral analysis. These results have been explained based on crystal structure considerations and quantum mechanical calculations. It has been shown that the PZC of kaolinite is at pH 4.2. Kaolinite exhibits good floatability in weakly acidic solution with dodecyl amine (DDA) collector. The negative zeta potential of kaolinite increases with an increase in pH, and hence the adsorption of DDA on kaolinite increases. However, the flotation of kaolinite decreases with an increase in pH and an increase in DDA adsorption. This anomalous flotation behavior is rationalized based on crystal structure considerations and particle aggregation phenomena. It is considered that the silica (001) and the alumina (001¯) basal planes of kaolinite are negatively charged. From quantum chemistry calculations, the interaction between DDA and the (001) plane was found to be stronger than at the (001¯) alumina plane due to the difference in the structure at the (001) and (001¯) planes. The self-aggregation between (001¯) faces and the edge planes and the adsorption of DDA at the silica (001) plane make the kaolinite aggregates hydrophobic, and good floatability is achieved in acidic solution. In alkaline solution, the kaolinite particles are dispersed. In the presence of DDA, hydrophobic aggregation appears to occur in alkaline solution between the (001) planes due to adsorbed DDA, and thus the hydrophilic (001¯) faces are exposed and flotation is not achieved. [Copyright &y& Elsevier]

Collecting properties of a new amphoteric collector (α-benzol amino benzyl phosphoric acid, BABP) for calcium-containing minerals were studied by micro-flotation tests and measuring mineral electrokinetic potentials and collector adsorption. The collector adsorption was confirmed by infrared spectroscopic characterization and adsorption determination. The results were interpreted based on solution chemistry calculations. BABP collector exhibited selectivity for fluorite and calcite in a weak alkaline medium. The increasing collecting power of BABP is apatite≪scheelite

Fluorite is a nonrenewable mineral used to produce anhydrous hydrofluoric acid (AHF) and aluminum fluoride. The demand for low-grade fluorite powder (CaF2 < 97%) has fallen sharply owing to the current market conditions. Therefore, a large number of fluorite concentrates have been improved by acid leaching. While this approach can efficiently remove CaCO3 from fluorite concentrate, the SiO2 content, which significantly affects AHF consumption during the production of HF or aluminum fluoride, cannot be completely removed. To solve this problem, in this study, we used reverse flotation before leaching the fluorite concentrates. Subsequently, the feasibility of reverse flotation desilication was determined. The obtained results of the ZP (zeta potential) measurements, solution chemistry analysis, FTIR (Fourier transform infrared spectroscopy) analysis, and micro-flotation tests indicated that employing dodecylamine as the collector and citric acid as the depressor could effectively separate sericite from fluorite. The batch flotation experiment and the pilot test were conducted in Chenzhou (Hunan, China) followed by their operation in Xinyuan Mining Co. Ltd., which produces monolithic fluorite ore on the large scale in Asia. Notably, we found that the contents of both SiO2 and Al2O3 were from 2.82%, 1.17% reduced to 1.28%, 0.74% in the batch flotation experiment. The results of the pilot test showed that the new reverse flotation + leaching technology could dramatically reduce the potential environmental impact and costs, thereby significantly improving the economic benefits by satisfying the requirements of the market. [ABSTRACT FROM AUTHOR]

• Study sheds new light on development and optimization of green depressants for flotation technology. • Research offers new low cost green depressants for sulfide minerals flotation separation. • Synthetic molecules depress pyrite flotation more strongly and selectively than chalcopyrite. • Costs and environmental impacts can be minimized by the use of synthetic depressants. Native starch has a complex molecular structure that limits its ability as a selective depressant in sulfide flotation separations. This research study was conducted primarily to develop a series of starch-based molecules of different molecular weights with the aim of obtaining the most selective depressant of pyrite in chalcopyrite flotation. Five low molecular weight molecules were produced by the oxidative treatment of starch using H 2 O 2 as the oxidant and FeSO 4 ·7H 2 O as the catalyst. Oxidation treatment resulted in molecular modification of starch, producing low molecular weight molecules of grafted polar groups with increased reaction time. The molecules developed were investigated by microflotation to obtain the most selective and effective depressant for pyrite than chalcopyrite. The optimal and most selective depressant was named tricarboxystarch (sodium salt), also known as TCSS, based on the results of characterization measurements. The inhibitory effect of tricarboxystarch on pyrite was far more selective and effective than native starch. Good selective separation between pyrite and chalcopyrite was achieved by adding tricarboxystarch to a low pH solution. Tricarboxystarch contained three –COOH and several –OH groups in the skeleton, providing excellent depression of pyrite. This study is a basic research that sheds new light on the development and optimization of organic polymers for flotation technology. [ABSTRACT FROM AUTHOR]

• Behaviors and mechanisms of electrochemical flotation of galena are reviewed. • Effects of electrochemical conditions on galena flotation behavior are discussed. • Effects of pulp chemistry on galena surface composition are described. • Applications of potential control flotation in industrial practice are introduced. Galena is the most important lead-containing mineral that has semiconductor properties which can cause electrochemical reactions during flotation. This paper reviews studies of galena electrochemical flotation behavior. The electrochemical mechanisms on galena surfaces of oxidation, collector adsorption and depression are described. Collectorless flotation requires a moderate oxidizing potential, and flotation cannot be achieved under reducing conditions. The hydrophobic entity of the galena surface for collectorless flotation may be elemental sulfur, lead polysulfide or the deficiency of lead. Chemisorbed xanthate, lead dixanthate, or dixanthogen may be responsible for xanthate-induced flotation. The flotation behavior can be optimized by adjusting and controlling pulp potential, dissolved O 2 , and solution pH. The addition of depressants can be directly involved in redox reactions between collectors and sulfide minerals, thereby depressing galena flotation. The grinding environment also greatly influences galena flotation. Various factors such as galvanic interactions, grinding media, gas atmosphere, solution pH, and hydrogen peroxide (H 2 O 2) formation can affect the extent of electrochemical reactions. This review proposes that research on sulfide mineral flotation should focus on the combination of theory and application of electrochemistry. [ABSTRACT FROM AUTHOR]

This study presents a highly selective reagent system that utilizes sodium hexametaphosphate (SHMP) to improve the separation of scheelite from calcite and fluorite using an anionic–nonionic collector. The recoveries of calcite and fluorite decreased to 20% as the SHMP dose exceeded 6 × 10−6 mol/L, whereas that of scheelite remained at 85%. The interaction mechanisms of minerals with SHMP were investigated through equilibrium speciation, Zeta potential, Fourier transform infrared spectrometry, and X-ray photoelectron spectroscopy analyses. SHMP exists as hydrogen phosphate anion in the aqueous solution with a pH of 7–12. Moreover, it may be adsorbed intensively on the positively charged surfaces of calcite and fluorite via electrostatic force or chelation with calcium ion to impede further adsorption of the assembled collector. By comparison, the adsorption of SHMP is feeble on the scheelite surface because of its negative charge. The roughing grade of low-grade scheelite ore is substantially improved from 0.74% to 1.65% compared with that in the contrast test in the absence of SHMP. [ABSTRACT FROM AUTHOR]

The influences of long-term static interaction between flotation reagents and minerals on mineral surface properties and their flotation behaviors were investigated in this work. Single mineral results showed that when the static interaction time between flotation reagents and minerals increased from 0 to 8 days, there were no significant differences in the recovery of fluorite (ranging from 77.50% to 74.50%), while the recovery of calcite dramatically decreased from 97.17% to 41.13%. The collector adsorption results indicated that after the long-term static interaction between the collector and minerals, adsorption and desorption of collector on the minerals occurred, and the adsorption amount of collector on fluorite and calcite varied from 0.396 mg/g to 0.421 mg/g, and from 0.444 mg/g to 0.404 mg/g, respectively. The contact angles of fluorite and calcite decreased from 134.3° and 105.0° for 0 days to 109.7° and 52.5° for 8 days, respectively, which demonstrated that the fluorite had a higher hydrophobicity than that of calcite after 8 days of static interaction between the minerals and collector. The Fourier transform infrared spectroscopy (FTIR) analysis showed that there were chemisorptions between the collector and the surfaces of the fluorite and calcite. Meanwhile, the X-ray photoelectron spectroscopy (XPS) results further elucidated that the amount of C=O from the oleic acid (OA) molecule for calcite treated for 8 days was less than for that treated for 0 days. In addition, the flotation results of the tailings from Jiangxi containing fluorite and calcite, indicated that the grade and recovery of fluorite increased from 87.18% and 40.99% for 0 days to 93.00% and 46.01% for 8 days, respectively, indicating that the separation of fluorite from calcite could be achieved via increasing the long-term static interaction between the flotation reagents and minerals. [ABSTRACT FROM AUTHOR]

The rejection of pyrrhotite and pyrite has become a long-standing problem in the copper ore industry. This paper describes the first successful depression and adsorption mechanism of a novel and non-hazardous reagent, polyglutamic acid (PGA), on pyrrhotite in the selective flotation of chalcopyrite with xanthate as the collector, making use of various laboratory-scale measurement techniques. The addition of PGA inhibited the flotation of pyrrhotite much more strongly than that of the chalcopyrite in a wide pH range. The prior addition of PGA achieved an improved selective flotation of chalcopyrite from pyrrhotite at pH 8, at which the grade and recovery of chalcopyrite in concentrate were over 80%. Surface measurement techniques including XPS spectral, IR spectral, zeta potential, and reagent adsorption analyses indicated that the PGA interacted differently with the two minerals, and had much greater affinity towards pyrrhotite than chalcopyrite. The presence of PGA blocked the electrochemical activity of the collector on the pyrrhotite surface and thus depressed its flotation, whereas the adsorption of the collector and its oxidation to dixanthogen were more effective on the chalcopyrite surface, indicating a weaker interaction of PGA with chalcopyrite. Our results suggest that the application of PGA could replace the toxic inorganic depressants in flotation technology, and could significantly reduce the environmental impacts of processing. [ABSTRACT FROM AUTHOR]

Pyrite is a major gangue mineral associated with galena and other valuable minerals, and it is necessary to selectively remove pyrite to upgrade the lead concentrate by froth flotation. In this study, the flotation experiments of a single mineral and mixed minerals were performed using chitosan with different molecular weights (MW = 2−3, 3−6, 10 and 100 kDa) as a depressant, ethyl xanthate as a collector, and terpineol as a frother, in a bid to testify the separation of pyrite from galena. Flotation results showed that the selective flotation of pyrite from galena can be achieved under the preferred reagent scheme, i.e., 400 g/t chitosan (10 kDa), 1600 g/t ethyl xanthate, and 100 g/t terpineol, while chitosan with other molecular weights cannot. Furthermore, the results of the zeta potential and contact angle measurements revealed that chitosan (10 kDa) has a strong adsorption on galena yet a very weak adsorption on pyrite at the dosage of 400 g/t. This study showed that chitosan (10 kDa) has great potential in the industrial flotation separation of pyrite from lead concentrates. [ABSTRACT FROM AUTHOR]

A scientific and rigorous study on the adsorption behavior and molecular mechanism of collector sodium oleate (NaOL) on a Ca2+-activated hydroxylated α-quartz surface was performed through experiments and density functional theory (DFT) simulations. The rarely reported hydroxylation behaviors of water molecules on the α-quartz (101) surface were first innovatively and systematically studied by DFT calculations. Both experimental and computational results consistently demonstrated that the adsorbed calcium species onto the hydroxylated structure can significantly enhance the adsorption of oleate ions, resulting in a higher quartz recovery. The calculated adsorption energies confirmed that the adsorbed hydrated Ca2+ in the form of Ca(H2O)3(OH)+ can greatly promote the adsorption of OL− on hydroxylated quartz (101). In addition, Mulliken population analysis together with electron density difference analysis intuitively illustrated the process of electron transfer and the Ca-bridge phenomenon between the hydroxylated surface and OL− ions. This work may offer new insights into the interaction mechanisms existing among oxidized minerals, aqueous medium, and flotation reagents. [ABSTRACT FROM AUTHOR]

The flotation separation of scheelite from calcite is problematic, where sodium silicate modified by polyvalent metal ions has shown some advantages for selective depression. In this study, an Al-Na2SiO3 polymer was used as the depressant for the flotation separation of scheelite from calcite using a lead complex of benzohydroxamic acid (Pb-BHA) as the collector. Furthermore, a number of measurements were conducted to investigate the structure of the Al-Na2SiO3 polymer and its adsorption behavior with Pb-BHA complexes on the mineral surface. Flotation experiments indicated that the Al-Na2SiO3 polymer shows good selectivity for the flotation separation of scheelite from calcite at pH 8, where the optimum ratio of sodium silicate to aluminum sulfate was 2:1. Fourier-Transform Infrared (FTIR) and solution chemical analyses revealed that aluminum hydroxide complexes and the hydroxy moiety of silicic acid are able to self-assemble via condensation affording an Al-Na2SiO3 polymer, i.e., a composite aluminosilicate polymer. The zeta potential measurements and adsorption capacity measurements indicated that, upon adsorption of the Al-Na2SiO3 polymer and Pb-BHA complexes on the mineral surface, the Al-Na2SiO3 polymer had less influence on the adsorption of Pb-BHA complexes on the scheelite surface, while the opposite was true for calcite. Therefore, more Pb-BHA complexes and fewer Al-Na2SiO3 polymers were deposited on the scheelite surface, while fewer Pb-BHA complexes and more Al-Na2SiO3 polymers were adsorbed on the calcite surface. The selective separation of scheelite from calcite was attributed to the cooperative selectivity of the Pb-BHA complexes and Al-Na2SiO3 polymer. [ABSTRACT FROM AUTHOR]

An efficiently optimized reagent regime was investigated to improve scheelite heating flotation. The scheelite grade and recovery in the plant were significantly improved by 5% and 6%, respectively, which remarkably augmented the economic profit by $260,000 per month. The interaction mechanisms of sodium sulfide and sodium oleate with scheelite, calcite and fluorite were evaluated by adsorption amount and Fourier transform infrared (FTIR) analyses. Sodium sulfide exhibited an excellent ability to promote the adsorption and desorption of sodium oleate on the scheelite surface and from the calcite and fluorite surfaces, thus facilitating the separation of scheelite from fluorite and calcite. [ABSTRACT FROM AUTHOR]

Pb–BHA complexes have been shown to be selective for the separation of tungsten and cassiterite minerals from calcium minerals. These minerals could be enriched synchronously to some extent using Pb–BHA complexes flotation. However, it is difficult to further improve the quality and recovery of the scheelite, wolframite, and cassiterite concentrate due to their different behavior in flotation, such as flotation rate and sensitivities to depressants. Moreover, the super fine particles create some challenges for the cleaning flotation process. In this study, advanced gravity separators for super fine particles were introduced for the cleaning process based on the slight difference in the specific gravity of scheelite, wolframite, and cassiterite. The new process featured pre-enrichment using Pb–BHA flotation, and upgrading using gravity separation, taking into account both the similarities and differences in floatability and density of the different minerals. The grades of WO3 and Sn in the concentrate of the new process reached to 61% and 2.89%, respectively, and the recovery of Sn was significantly improved. In addition, gravity separation is highly efficient, cost effective, and chemical-free, which is environmentally friendly. This study has proven that physical separation can be used for the purification of flotation products and provide some solutions for separation problems of complex refractory ores, which has, up until now, been rarely reported in the literature and/or applied in mineral processing. [ABSTRACT FROM AUTHOR]

A portion of dodecyl amine (DDA) in a muscovite flotation system was replaced with alcohols with different carbon-chain lengths. These alcohols included octanol (OCT); decanol (DEC); dodecanol (DOD); and tetradecanol (TER). The muscovite adsorption behavior of the mixed DDA and alcohol systems were investigated through zeta potential; contact angle; and adsorption quantity tests. Single-mineral flotation tests showed that the muscovite-collecting power of the mixed DDA/alcohol (OCT, DEC, or DOD) system was stronger than that of the pure DDA system. The muscovite-collecting power of the collector systems decreased in the following order: DDA/DEC > DDA/OCT > DDA/DEC > DDA > DDA/TER. Zeta potential and contact angle analysis indicated that when combined with DDA; alcohols physically adsorbed on the surfaces of muscovite. This behavior improved the hydrophobicity of muscovite. Furthermore, adsorption analysis revealed that synergy between DDA and alcohol enhanced the adsorption of alcohol on muscovite. DDA has a dominant role in synergistic adsorption; whereas alcohol has a supporting role. Among all tested alcohols; DDA and DOD exhibit the highest synergetic adsorption effect because of their similar carbon-chain lengths. This similarity promotes the formation of a compact adsorption layer on the muscovite surface. [ABSTRACT FROM AUTHOR]

• SFG provides molecular details about the adsorption of sodium silicate (SS). • SFG signal shows the change in surface charge and adsorption. • SS physically adsorbs at CaF 2 surface at pH < 7 and is removed by water flow. • SS chemically adsorbs at CaF 2 surface at pH > 7 and is unremoved by water flow. • SS penetrates the innermost water layer at SiO 2 surface and adsorbs on it chemically. Sodium silicate (SS) is often used as a depressant or a dispersant to improve the selectivity of froth flotation. The depressing ability of SS changes with its concentration and the solution pH. However, the depressing mechanism is unclear. In this paper, sum frequency generation spectroscopy was used to investigate the water structure at the mineral-water interface to provide a molecular understanding of SS adsorption and its role in flotation. Our study shows that a significant amount of silicate species adsorbs at the fluorite-water and silica-water interfaces in a wide range of pH, independently of the surface potential. The adsorption layer of silicate species on the fluorite surface can be removed at low pH (acidic condition), but its removal becomes difficult at high pH (basic condition). On the contrary, the adsorption of silicate species at the silica surface is so strong that the adsorbed species cannot be removed at the whole pH range. This finding agrees with flotation results showing that SS can be used as a dispersant for fluorite at pH = 6–8, but it behaves like a depressant at higher pH. Also, SS effectively depresses the silica floatability at the whole range of pH due to its strong interaction with the mineral surface. This work provides the molecular details about the SS adsorption onto the mineral surface which is complementary to the previous macroscopic studies such as FTIR, zeta potential, and XPS measurements. [ABSTRACT FROM AUTHOR]

Highlights • Propyl gallate was used as a excellent flotation collector for fluorite. • Separation of fluorite from calcite without using any depressant can be achieved. • The flotation mechanism of fluorite from calcite was studied. • Adsorption of PG onto the surfaces of fluorite and calcite was studied. Abstract In real flotation systems, the flotation separation of fluorite from calcite is a challenge due to the similar surface properties of these two minerals. The purpose of this paper is to develop a highly selective flotation collector for the separation. Propyl gallate (PG) was introduced as a collector for selective flotation separation of fluorite from calcite. The separation of fluorite from calcite without using any depressant can be achieved by using PG as the collector. The flotation mechanism of fluorite and calcite was studied by zeta potential measurements, adsorption, FT-IR and XPS analysis. The results indicated that phenolic hydroxyls were the functional groups of PG which can selectively adsorb on fluorite, and the adsorption amount of PG on the surface of fluorite was larger than on calcite. [ABSTRACT FROM AUTHOR]