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To address the issue of mediocre separation efficiency of depressants in the copper-lead separation process, this article synthesized a macromolecular organic depressant, polymaleic anhydride-ethylenediaminetetraacetic acid (PMA–EDTC), using a polycarboxylic macromolecule as the backbone and also introducing –N–(C=S)–S– as the solidophilic group and employed as a galena depressant. The structure of PMA–EDTC was characterized using Fourier transform infrared (FT-IR). The effect of PMA–EDTC on the floatability of galena and chalcopyrite was investigated through micro-flotation and Contact angle measurements. The experimental results demonstrated that PMA–EDTC exhibited selectivity inhibition towards galena rather than chalcopyrite across a wide pH range. At a dose of 8 mg/L, there was effective separation between galena and chalcopyrite with a separation coefficient of 24.17, effectively altering the floatability of galena while having little impact on the floatability of chalcopyrite. The selective inhibition behavior and adsorption mechanism of PMA–EDTC on galena and chalcopyrite were investigated using FT-IR, Zeta potential, and X-ray photoelectron spectroscopy (XPS). FT-IR and Zeta potential studies indicated that PMA–EDTC formed chemical adsorption on the surface of galena. XPS confirmed the model of chemical adsorption of PMA–EDTC on lead atoms in the galena surface. The results indicate that PMA–EDTC adsorbs on the surface of galena via its –(C=S)–S–group, forming a hydrophilic complex and achieving selective depression of lead and the cleaning flotation of copper. [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]

Recent years have witnessed growing research interest in applying rheology in grinding and flotation treatment of finely disseminated ores. Slurry rheology has long been identified as the comprehensive effect of inter-particle interactions, including their aggregation and dispersion states in slurry, which are more impactive under the fine-particle effect. In this regard, rheology has the potential to play a significant role in interpreting the flowing and deforming phenomena of inter-particle aggregates, particle-bubble aggregates, and flotation froth. Though much attention has been paid to the rheological effect in industrial suspension, this has not been the case for mineral grinding and flotation for fine particles. The influential mechanism of rheology on the sub-processes of mineral processing has not been systemically determined nor revealed thoroughly, thus the underpinning mechanism for enhancing the processing efficiency has been difficult to discover. This paper reviews the current application and importance of rheology in fine mineral processing, and the potential research direction in the field is proposed. [ABSTRACT FROM AUTHOR]

In this paper, a novel macromolecular depressant of hematite, polymaleic anhydride-triethylenetetramine (PMTA) with multiple carboxyl and amine groups, has been synthesized and used for cationic reverse flotation separation of quartz from hematite. The structure is characterized by Fourier transform infrared spectroscopy (FT-IR). The depression performance and adsorption mechanism of PMTA onto hematite and quartz surface are investigated by micro-flotation tests, FT-IR, zeta potential and X-ray photoelectron spectra (XPS). The micro-flotation results indicate that PMTA exhibits a good depression performance compared to starch. We find that 98.29% of hematite is depressed with a grade of 65.24% at pH 11 with 12 mg/L dosage. The FT-IR spectra, zeta potential and XPS analysis demonstrate that PMTA may mainly chemisorb on the hematite surface by Fe O bonds, and mainly adsorb on the quartz surface by hydrogen bond interaction. PMTA could be a good depressant of hematite in the separation from quartz. [ABSTRACT FROM AUTHOR]

[Display omitted] • In situ high-temperature XRD investigation on the pyrolysis of gold-bearing pyrite. • Microwave-induced phase transition from isometric pyrite to hexagonal pyrrhotite. • "Hot spots" are responsible for the formation of many holes inside mineral particles. • The generation of polycrystalline aggregates of nanoscale pyrrhotite was confirmed. • Under inert atmospheres, the conversion from S 2 2− to S2− and S0 avoids air pollution. Microwave pretreatment of gold-bearing sulfides in an inert atmosphere has served as a promising technique to improve the extraction of gold. However, the complex decomposition mechanism of gold-bearing pyrite under microwave irradiation has not been completely clarified. This study employs in-situ and ex-situ X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) to investigate the phase transformation and sulfur conversion during microwave pyrolysis of gold-bearing pyrite. The removal of sulfur from gold-bearing pyrite caused a significant change at about 600 °C with an activation energy of 223.02 kJ·mol−1. The phase transformation during in-situ heating of gold-bearing pyrite occurred at 500–600 °C, and the crystal lattices underwent thermal expansion along the c-axis direction. Under microwave irradiation, iron (Fe) and sulfur (S) atoms in pyrite rearranged themselves to form different types of pyrrhotite in space groups P31 and P63/mmc, and the symmetry of crystal structure became disordered. After microwave pyrolysis, the formation of polycrystalline aggregates consisting of nanoscale pyrrhotite and unreacted pyrite was confirmed in the TEM study. Microwave-induced hot spots should be responsible for the appearance of numerous holes inside mineral particles. Additionally, the sulfur in pyrite (S 2 2− and S n 2−) was converted to monosulfide (S2−) in pyrrhotite and elemental sulfur (S0), potentially reducing air pollution caused by exhaust emissions. This work provides further insights into the decomposition mechanism of gold-bearing pyrite in the microwave field, and it may help advance the application of microwave pretreatment under inert atmospheres in gold extraction. [ABSTRACT FROM AUTHOR]

[Display omitted] • The utilization of DMB in reverse separate of feldspar from apatite was attempted. • Reverse flotation of feldspar from apatite realized using DMB as a collector. • The interaction of DMB with feldspar was stronger than that of DMB with apatite. • The interaction of DMB with feldspar surface was considered as hydrogen bonding. The utilization of a new collector 1-Dodecyl-3-methylimidazolium bromine (DMB) ionic liquid in the reverse flotation of feldspar from apatite was researched through a series of experiments. The micro-flotation results exhibited that DMB had a good collecting for feldspar while it had little floatability for apatite, and the artificial mixed minerals flotation presented the reverse flotation separation of feldspar from apatite can be realized well by adding the DMB collector. The foam collapse results illustrated that DMB has better foam properties for reverse flotation compared to dodecylamine (DDA). The zeta potential and Fourier Transform Infrared Spectroscopy (FT-IR) measurements indicated that the interaction of DMB with the feldspar surface was much stronger than that of DMB with the apatite surface. The XPS analysis further suggested that the interaction between DMB and apatite surface was weak while that between DMB and feldspar surface was hydrogen-bonding adsorption. As such, this work is expected to provide a meaningful guide for the selection/design of a cationic collector in reverse flotation of feldspar from apatite. [ABSTRACT FROM AUTHOR]

• Galena and sphalerite floated well using diethyldithiocarbamate (DTC) as collector. • Cationic guar gum (CGG) exhibited selective depressant effect on sphalerite. • Only adding CGG after DTC could realize the separation of galena from sphalerite. • Addition order of CGG and DTC could lead to remarkable adsorption difference. In this study, the effect of cationic guar gum in the flotation separation of galena from sphalerite when diethyldithiocarbamate acted as galena collector was investigated, mainly through flotation tests and ToF-SIMS analysis. The flotation results showed that the cationic guar gum could selectively depress the sphalerite flotation and enhance the preferential flotation of galena only when it was added after collector diethyldithiocarbamate. The ToF-SIMS analysis found that addition of cationic guar gum after diethyldithiocarbamate exhibited no effect on the collector adsorption on galena surface but could selectively inhibit the collector coverage on sphalerite surface, and further result in the floatability difference. [ABSTRACT FROM AUTHOR]

Scheelite associated with calcium-containing minerals such as calcite and fluorite is difficult to separate by flotation because of the Ca ions contained in the mineral lattices, which cause scheelite to have similar surface properties and floatability to gangue minerals. Traditional collectors such as oleic acid need to add a large amount of sodium silicate as gangue inhibitors, which causes difficulties for the settlement of tailings. In addition, the use of benzohydroxamic acid (BHA), which needs the addition of Pb(NO3)2 as the scheelite activator, can also cause environmental pollution. In this paper, Fe-BHA, a new collector containing the iron complex, was studied to investigate its flotation ability of scheelite, as well as its BHA/FeCl3 ratio on scheelite flotations. In the single mineral flotations, the Fe-BHA showed a significant difference in the flotation recoveries of scheelite and calcite, with a scheelite recovery of 77.03% at pH 8.0 and calcite recovery of 16.69% at the same pH. The results of the roughing tests of Xianglushan actual ore showed that the scheelite with Fe-BHA (500 g/t BHA and 200 g/t FeCl3) and 40 g/t oleic acid as collectors obtained satisfactory flotation results with a WO3 grade of 1.56% and WO3 recovery of 65.52%, which were much higher than those of scheelite with BHA or oleic acid as the collector, but there was still a gap with those of scheelite using Pb(NO3)2 as activation and BHA as the collector. The UV-Vis curves of the Fe-BHA with different BHA/FeCl3 ratios indicated that the Fe-BHA chelates might have several different structural forms, and the single mineral tests of the BHA/FeCl3 ratios showed that when the molar ratio of benzohydroxamic acid to FeCl3 was about 1.2:1, the best scheelite flotation result was obtained in this test. In addition, the XPS analyses proved that the adsorption of the Fe-BHA on the scheelite surface occurred, and by fitting the peaks of Ca 2p and O 1s of scheelite, it was found that the mechanism of the Fe-BHA acting on the Ca sites of the scheelite surface was through the removal of H2O from the Ca-OH of scheelite and Fe-OH from Fe-BHA to form Fe-O-H. [ABSTRACT FROM AUTHOR]

In this study, the performance of 2-hydroxy-3-naphthylmethyl hydroxamic acid (NHA) in cassiterite flotation was investigated. The aim was to understand the mechanism of action of NHA for the first time. The effect of NHA as a collector in the flotation separation of cassiterite, calcite, and quartz was investigated via microbubble flotation experiments. The experimental results showed that the maximum recovery of cassiterite in the presence of NHA was 91.76%. This was attributed to the selective adsorption of NHA on the cassiterite surface. NHA showed a stronger collection performance for cassiterite than calcite and quartz. Therefore, the mechanism of NHA-cassiterite interaction was investigated using zeta potential, the logarithmic solubility plot (LSD), Fourier Transform Infrared (FT-IR), X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscope (SEM) analyses. This study introduces a new adsorption process and mechanism for the NHA-based adsorption of cassiterite. The results show that, under neutral conditions, the solute components of cassiterite surface lattice ions mainly exist in the form of Sn–OH complexes. Chemisorption occurs between cassiterite and NHA which is adsorbed onto the cassiterite surfaces through interaction with O sites, rather than Sn sites as is traditionally expected. Further, the hydroxyl and hydroxyl groups of NHA are chemically coordinated with Sn–OH on the surface of cassiterite to form a six-membered chelate ring. This proposed mechanism can be extended to most systems in which metal ions interact with hydroxamic acids bearing hydroxyl groups. This contributes to a better understanding of the activation mechanism of hydroxamic acid collectors in cassiterite flotation. [ABSTRACT FROM AUTHOR]

In present research, a new chelating collector S -carboxymethyl- O , O ′-dibutyl dithiophosphate (CMDT) was used in the flotation separation of malachite from quartz. The flotation performances of CMDT on malachite (Cu 2 CO 3 (OH) 2 and quartz (SiO 2) were evaluated by micro-flotation tests. The flotation results demonstrated that CMDT exhibited a stronger adsorption and a better selectivity on malachite against quartz. A good separation efficiency for artificially mixed minerals was obtained at pH around 9.0 with Na 2 S as a regulator together. The CMDT adsorption mechanism was investigated and analysed by Fourier transform infrared spectroscopy (FT-IR), zeta potential and X-ray Photoelectron Spectroscopy (XPS) analysis. The FT-IR spectra showed that CMDT could react with Cu2+ ions and might adsorb on malachite surface by strong chemisorption. On the other hand, zeta potential and XPS analysis results provided enough evidences that CMDT possessed a stronger affinity on malachite than quartz. Unlabelled Image • CMDT is innovatively used as malachite collector. • CMDT shows excellent flotation performance for malachite against quartz. • Cu2+ ions released by malachite could promote the recovery of quartz with CMDT. • Adsorption mechanism of CMDT on malachite surface is revealed by FT-IR and XPS. [ABSTRACT FROM AUTHOR]

Zn ions are widely reported to possess a depression effect on sphalerite in flotation. The effective adsorption of Zn ions on a sphalerite surface is critical to realize the inhibition effect. At the same time, zinc ions are easily hydrated in a slurry solution. Therefore, based on the first principle DFT calculation, the molecular mechanism of Zn ion adsorption on the surface of Sphalerite is further studied from the perspective of hydration. [Zn(H2O)5]2+, [Zn(OH)(H2O)3]+ and [Zn(OH)2(H2O)2] are found to be the effective components of Zn ions adsorbed on a sphalerite (110) surface in the neutral condition. Furthermore, the adsorption mechanism of [Zn(H2O)5]2+ on a sphalerite (110) surface is mainly via the hybridization of Zn 3d orbital in the structure of [Zn(H2O)5]2+ with surface S 3p orbitals. Additionally, the adsorption mechanism of [Zn(OH)(H2O)3]+ and [Zn(OH)2(H2O)2] on a sphalerite (110) surface is primarily ascribed to the hybridization of surface Zn 3d orbital with O atom of hydroxyl ligand 2p orbitals. In addition, the H 1s orbits in the water molecules have a weaker interaction with the sphalerite surface S 3p orbits. This work sheds new light on the adsorption and inhibition mechanism of zinc ions on a sphalerite surface in a neutral aqueous solution. [ABSTRACT FROM AUTHOR]

Sphalerite is a common sulfide mineral, and xanthate is usually used as the collector of sphalerite flotation. In order to realize the simultaneous flotation of sphalerite- and zinc-containing oxide ores, in this paper, dodecylamine was used as the collector and sodium sulfide as the regulator to explore the flotation behavior of sphalerite in a sulfuration–amine system through single mineral flotation tests, and several analytical methods, including contact angle measurement, adsorption capacity test, FT-IR, and XPS, were employed to discuss the interaction mechanism of dodecylamine on the surface of sphalerite. The results confirm that dodecylamine had a strong collecting effect on sphalerite throughout almost the entire pH range, and the flotation recovery increased with the increase in pH, reaching 86.81% at pH 12. It was found that the effect of sodium sulfide on the floatability of sphalerite was relatively weak, and a weak activation effect, of about 2% improved recovery, was achieved. The results of the mechanism analysis further show that dodecylamine underwent both physical adsorption and chemical adsorption on the surface of sphalerite, and the physical adsorption was enhanced with the increase in pH. The above findings provide evidence for the simultaneous flotation of zinc-containing sulfide-oxide mixed minerals. [ABSTRACT FROM AUTHOR]

Sulfuration-amine flotation is the most commonly used method to separate zinc oxide ore, but its shortcomings such as unstable separation index and poor applicability to high mud-content raw ore limit its application in industry. In this study, the influence mechanism of sodium carbonate on the flotation separation of smithsonite and calcite by the sulfuration-amine method was investigated by chemical analysis of the flotation solution, contact angle measurement, Zeta potential test, and XPS analysis. The results showed that sodium carbonate significantly improved the flotation separation performance of smithsonite and calcite. The chemical analysis of the flotation solution showed that sodium carbonate hindered the dissolution of smithsonite, reducing its negative impact on the flotation of smithsonite. The results of the zeta potential and XPS tests showed that sodium carbonate enhanced the electronegativity of the smithsonite surface, and in an alkaline environment, sodium carbonate was favorable for the adsorption of dodecylamine on the surface of smithsonite, while sodium carbonate and high alkalinity enhanced the inhibitory effect of sodium hexametaphosphate on calcite. The study proved that sodium carbonate could be an effective modifier to promote the flotation separation of smithsonite and calcite using the aulfuration-amine method. [ABSTRACT FROM AUTHOR]

In this work, the magnetic Zr-based MOF composites with excellent retrievability were prepared using Fe3O4@SiO2 as the core and UiO–66–NH2 as the shell. Fe3O4@SiO2 core could introduce mesopores and result in capillary condensation in MOF composites, which aggravated with the dosage of Fe3O4@SiO2. The as-synthesized MOF composites could be rapidly retrieved from aqueous solution via magnetic separation in 10 seconds. pH imposed an important effect on Au (III) adsorption by governing the ion exchange and electrostatic interaction between Au (III) anions and adsorbents, and the optimal adsorption happened at pH 7. The adsorption process fitted well with the pseudo-second order kinetics model and Langmuir adsorption model. The maximum adsorption capacity of Au (III) by FSUN–10 and FSUN–50 at 298 K were determined to be 611.18 mg∙g−1 and 463.85 mg∙g−1, respectively. Additionally, Au (III) uptakes increased with temperature. Beyond experiments, the adsorption mechanisms were thoroughly studied through systematic characterization, molecular dynamics simulation (MDS) and density functional theory (DFT) study. It was verified that Au (III) was adsorbed via coordination to hydroxyl and amino groups and was reduced to Au (I) and Au (0) by amino groups. The diffusion coefficient of Au (III) along UiO–66–NH2 was calculated to be 5.8 × 10−5 cm2∙s−1. Moreover, the magnetic Zr-based MOF composites exhibit great industrial value in gold recycling with high adsorption selectivity and good recyclability. [ABSTRACT FROM AUTHOR]

In order to achieve the effective separation of copper-molybdenum in the presence of xanthate and kerosene, carrageenan was explored as a novel environmentally friendly molybdenite depressant in this work. The flotation behavior of molybdenite was studied by micro-flotation tests, and the depression mechanism was investigated through zeta potential, Fourier Transform Infrared Spectroscopy (FTIR) and atomic force microscope (AFM) analysis. The flotation results showed that molybdenite was significantly depressed by carrageenan in the pH range of 6–12 even in the presence of xanthate and kerosene. Zeta potential, FTIR and AFM measurement demonstrated that carrageenan could adsorb strongly on the molybdenite surface and change the surface wettability of molybdenite, thus significantly reducing the floatability of molybdenite. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnesite was efficiently separated from dolomite with gellan gum as depressant. • Gellan gum exhibited excellent selective depression effect on the dolomite. • Gellan gum adsorbed stronger on the dolomite than magnesite. • A conceivable flotation separation model of magnesite and dolomite was proposed. Flotation technology is an effective way to separate magnesite from dolomite. However, the efficient separation of magnesite from dolomite in sodium oleate (NaOL) system is rather challenging without depressants due to their highly similar physicochemical surface properties. Herein, gellan gum (GG) was employed as a new flotation inhibitor in separating magnesite from dolomite. The depression performance and inhibitory mechanism were systematically studied by flotation experiments, and a number of surface testing technologies. Flotation experiments indicated that GG greatly affected the floatability of dolomite, whereas it had little impact on the magnesite flotation. The artificial mixed mineral experiments confirmed that effective separation of magnesite and dolomite was fulfilled with GG as flotation inhibitor. Zeta potential analyses, surface wettability measurements, and Fourier transform infrared (FTIR) spectroscopy tests indicated that GG strongly prevented the NaOL adhesion on the dolomite, while it scarcely impeded the NaOL adhesion onto magnesite. X-ray photoelectron spectroscopy (XPS) detections demonstrated that GG adhered stronger towards dolomite than magnesite, which was mainly due to its higher affinity towards Ca2+. AFM images intuitively identified that much stronger interaction and thicker adsorption layer occurred on the dolomite than magnesite. Additionally, higher adsorption concentration, closer adsorption distance and hither adsorption strength of GG on the dolomite was further confirmed by molecular dynamics (MD) simulations. Therefore, GG was a promising flotation depressant to separate magnesite from dolomite and achieve the efficient exploitation of magnesite resources. [ABSTRACT FROM AUTHOR]

[Display omitted] • TTCBT/BO/BI S atoms react with pyrite Fe atoms to form covalent bonding. (74/85) • Heterocyclic collectors adsorbed stronger under acidic condition. (66/85) • Thione form was the most stable adsorption form under acidic condition. (73/85) • MBTH, TTCBTH and TTCBIH gave stronger adsorption and high recoveries. (71/85) • Linear correlation between the recoveries and hydrated adsorption energies. (77/85) This study adopted both computational and experimental approaches to design by modification of 2-mercaptobenzothiazole (MBT), 2-mercaptobenzoxazole (MBO) and 2-mercaptobenzimidazole (MBI) heterocyclic collectors by introducing a carbon sulphide (–CS 2) group and forming 2-trithiocarbonatebenzothiazole (TTCBT), 2-trithiocarbonatebenzoxazole (TTCBO) and 2-trithiocarbonatebenzomidazole (TTCBI) derivatives collectors. The adsorption behaviour of the heterocyclic collectors (and derivatives) on pyrite and subsequent hydrophobicity at different pH conditions were characterised using molecular modelling and microflotation approaches, respectively. The computational adsorptions were performed on dry and hydrated surfaces in their neutral thiolate and thione (acidic) form on the pyrite (1 0 0) surface. It was found that under dry and neutral conditions the TTCBONa and TTCBTNa were more exothermic, while under dry and acidic conditions the TTCBIH was more exothermic followed by MBIH and MBTH. Under hydrated and neutral conditions MBONa was predicted as the most exothermic, while for hydrated and acidic conditions MBTH, TTCBTH and TTCBIH were more exothermic. It was found that under acidic conditions, the heterocyclic collectors were more exothermic than for neutral condition on the hydrated surface. The microflotation at pH = 8 showed that MBO achieved higher recoveries, while at pH = 6 MBT, TTCBT and TTCBI achieved higher recoveries that could reach 90 %. The derivatives under acidic conditions were found to have good recovery performance, which showed that the introduction of a –CS 2 group on the exocyclic sulphur atom improved the affinity and therefore hydrophobicity of the mercapto-heterocyclic collectors on the pyrite surface, and thus these derivatives can enhance the flotation of pyrite minerals. In addition, the computational predictions complimented by experimental recoveries are essential to a meaningful development of modelling as a tool in mineral processing reagent design. [ABSTRACT FROM AUTHOR]

[Display omitted] • DMNS could selectively depressed the dolomite flotation using NaOl as a collector. • Flotation separation of apatite from dolomite can be achieved with the DMNS/NaOl scheme. • DMNS weakly interacted with the apatite surface but it chemically adsorbed onto the dolomite surface. • A possible interaction model of the reagents on the apatite/dolomite surface is proposed. To address the flotation separation problem between apatite and dolomite, DMNS (disodium methylenebis naphthalene sulfonate) was selected as a depressant in this research. Micro-flotation results showed NaOl exhibited good floatability for dolomite and apatite, with no significant difference in the floatability between these two minerals. The addition of DMNS completely depressed the floatability of dolomite but slightly affected the floatability of apatite. The artificial minerals mixture flotation ensured that DMNS achieved the separation between apatite and dolomite when the NaOl was used. The adsorption measurement illustrated adsorption amount of DMNS on dolomite surface was more than that of it on apatite surface, the Zeta potential results illustrated NaOl still adsorbed on the apatite surface but did not adsorbed on the dolomite surface after conditioning with DMNS. XPS analysis verified that no effective interaction occurred between DMNS and apatite surface, and DMNS chemically adsorbed on the dolomite surface by the interaction between –SO 3 H groups of DMNS and Ca2+/Mg2+ of the dolomite surface. First-principles calculations further ensured the higher adsorption energy of DMNS on the dolomite surface. The computational calculation also revealed that the interaction of DMNS with the dolomite surface was much stronger than that with the apatite surface. [ABSTRACT FROM AUTHOR]

Metal ions have been used to improve the flotation recovery of muscovite, while the enhancement mechanism is still unclear. In this paper, density functional theory (DFT) calculations and molecular dynamics (MD) simulations were employed to investigate the adsorption structure of sodium oleate (NaOL) on muscovite surface, and the diffusivity and foaming of NaOL in the pulp system, in presence of Fe3+ at different pH range. DFT calculation results suggested that the adsorption of iron ions, include FeOH2+ and Fe(OH) 2 +, could change the surface charge from negative to positive, thus enhancing binding performance for OL−. Moreover, MD simulations indicated that the distribution of iron ions in aqueous solution can significantly affect the dispersion of sodium oleate molecules. Specifically, FeOH2+ may lead to the complexation of oleate ions and result in the agglomeration, which is not conducive to its dispersion in solution. However, Fe(OH) 2 + can significantly inhibit the aggregation of OL− molecules, and accelerate the dispersion of OL− in flotation pulp. This work reveals atomic-level mechanism of Fe ion on the dispersion and adsorption of sodium oleate in pulp, which is helpful to the understanding of minerals flotation behavior in presence of metal ions. [Display omitted] • The mechanism of Fe3+ on muscovite flotation was explored by DFT and MD calculations. • Fe3+ ions could change muscovite surface charge and enhance adsorption of OL-. • Fe3+ ions could affect the dispersion behavior of OL- in flotation pulp. [ABSTRACT FROM AUTHOR]

[Display omitted] • Flotation separation of bastnaesite from calcium-bearing gangue minerals (C). • C refer to fluorite and calcite. • Oxalic acid (OA) can selective replace H205 on the surface of C. • The inhibition degree of OA on fluorite is greater than that of calcite. • The inhibition performance of OA was predicted by simulation and calculation. Bastnaesite is a major light rare earth resource in the earth, which is difficult to separate from calcium-bearing gangue minerals in flotation because of their similar flotation characteristics as the semisoluble salt minerals. To address this problem, in 3-hydroxy-2-naphthyl hydroxamic acid (H205) system, the selective inhibition mechanism of oxalic acid on common calcium-bearing gangue minerals (calcite and fluorite) in bastnaesite flotation was studied by flotation tests, solution chemistry analysis, zeta potential measurements, and X-ray photoelectron spectroscopy (XPS) measurements, combined with thermodynamics and density functional theory (DFT) calculation. After the analysis of those tests and calculation results, it can be known that the hydrophilic oxalic acid can selectively compete with H205 for the active site (Ca2+) on the surface of the calcium-bearing gangue minerals, thus reducing its surface hydrophobicity and inhibiting its floating, while bastnaesite is not susceptible. In this process, fluorite is more inhibited than calcite. [ABSTRACT FROM AUTHOR]

Fluorite as the main source of fluorine generally coexists with calcite. The highly similar floatabilities and physicochemical properties make it tough to separate these two minerals. Herein, gellan gum (GG) was used as depressant to separate fluorite from calcite for the first time. Several experiments and tests were utilized to explain the inhibiting performance and mechanism of GG. Flotation experiments illustrated that GG displayed an outstanding depression performance for the calcite flotation, whereas it hardly depressed fluorite. Zeta potential analyses, surfaces wettability measurements and Fourier transform infrared (FTIR) indicated that GG strongly adhered onto calcite and prevented the NaOL from adhering on it. Adsorption amount measurements indicated that the GG adhered onto calcite with a higher amount compared to fluorite. X-ray photoelectron spectroscopy (XPS) tests pointed out that GG adsorbed onto calcite and fluorite surfaces by strong chemisorption and weak physisorption, respectively. Atomic force microscopy (AFM) measurements implied visually that GG adsorbed denser and stronger on the calcite than fluorite. Molecular dynamics (MD) simulations demonstrated that compared with fluorite, more GG adsorbed on the calcite surface due to the reaction between hydroxyl groups and the mineral surface, as evidenced by higher diffusion coefficient for water (D water) value, smaller interaction distance, and higher relative concentration of GG on the calcite surface. Therefore, GG could be employed as a promising flotation depressant in separating fluorite from calcite. Diagram of the mechanism of flotation separation of calcite and fluorite. [Display omitted] • Fluorite was efficiently separated from calcite with gellan gum as depressant for the first time. • Gellan gum exhibited excellent selective depression effect on the calcite flotation. • Gellan gum chemically adsorbed on the calcite surface. • Gellan gum strongly prohibited the NaOL adsorption onto calcite. [ABSTRACT FROM AUTHOR]

[Display omitted] • S-Triazine S and N1 atoms react with cooperite Pt atoms to form covalent bonding. (82/85) • SDTBAT adsorbs stronger than xanthate and dithiocarbamate: SDTBAT > SNBDTC > SNBX. (83/85) • DOS and atomic charges depicted charge gain on Pt and loss on S atoms. (71/85) • SDTBAT exhibited strong adsorption on cooperite. (52/85) • Adsorption energies are stronger on dry surface compared to hydrated surface. (78/85) The high demand of platinum has drawn much attention on the recovery of the platinum group minerals (PGMs). Cooperite (PtS) is one of the major sources of platinum which is found in high concentration as sulphide minerals in the Platreef. This current study used the density functional theory with dispersion correction method and applying the U-parameters (DFT-D + U) to understand the interaction of the well-known collectors, sodium normal butyl xanthate (SNBX) and sodium normal butyl dithiocarbamate (SNBDTC) which are utilised in industry in comparison with the green novel sodium 2,6-dithio-4-butylamino-1,3,5-triazine (SDTBAT) collectors on dry and hydrated cooperite (1 0 1) surface. In the adsorptions, different adsorption sites were initially tested on dry surface, to identify the most preferred active and exothermic site of the colletors on the surface. The SNBX and SNBDTC collectors preferred to form a binuclear-bidentate, while the SDTBAT formed trinuclear-tridentate bonding on the 3-coordinated Pt atoms of the PtS (1 0 1) surface. The adsorption energies on dry surface were in the order as: SDTBAT > SNBDTC > SNBX. The adsorption energies of collectors on hydrated PtS (1 0 1) surface also followed similar adsorption trend (SDTBAT > SNBDTC > SNBX). This suggested that SDTBAT had strong affinity with the surface. Most importantly it was found that the hydrated condition adsorption energies were significantly reduced compared to the dry condition adsorption energies. It was apparent that the SDTBAT collector displayed an ability to improve the recovery of the cooperite mineral and therefore a potential replacement of the well-known dithiocarbamate and xanthate collectors for use in PGMs. [ABSTRACT FROM AUTHOR]

[Display omitted] • S-Triazine S and N1 atoms react with cooperite Pt atoms to form covalent bonding. (82/85) • SDTBAT adsorbs stronger than xanthate and dithiocarbamate: SDTBAT > SNBDTC > SNBX. (83/85) • DOS and atomic charges depicted charge gain on Pt and loss on S atoms. (71/85) • SDTBAT exhibited strong adsorption on cooperite. (52/85) • Adsorption energies are stronger on dry surface compared to hydrated surface. (78/85) The high demand of platinum has drawn much attention on the recovery of the platinum group minerals (PGMs). Cooperite (PtS) is one of the major sources of platinum which is found in high concentration as sulphide minerals in the Platreef. This current study used the density functional theory with dispersion correction method and applying the U-parameters (DFT-D + U) to understand the interaction of the well-known collectors, sodium normal butyl xanthate (SNBX) and sodium normal butyl dithiocarbamate (SNBDTC) which are utilised in industry in comparison with the green novel sodium 2,6-dithio-4-butylamino-1,3,5-triazine (SDTBAT) collectors on dry and hydrated cooperite (1 0 1) surface. In the adsorptions, different adsorption sites were initially tested on dry surface, to identify the most preferred active and exothermic site of the colletors on the surface. The SNBX and SNBDTC collectors preferred to form a binuclear-bidentate, while the SDTBAT formed trinuclear-tridentate bonding on the 3-coordinated Pt atoms of the PtS (1 0 1) surface. The adsorption energies on dry surface were in the order as: SDTBAT > SNBDTC > SNBX. The adsorption energies of collectors on hydrated PtS (1 0 1) surface also followed similar adsorption trend (SDTBAT > SNBDTC > SNBX). This suggested that SDTBAT had strong affinity with the surface. Most importantly it was found that the hydrated condition adsorption energies were significantly reduced compared to the dry condition adsorption energies. It was apparent that the SDTBAT collector displayed an ability to improve the recovery of the cooperite mineral and therefore a potential replacement of the well-known dithiocarbamate and xanthate collectors for use in PGMs. [ABSTRACT FROM AUTHOR]

In order to unravel the oxidation mechanism(s) of chalcopyrite (CuFeS 2) surfaces, the surface anisotropy of CuFeS 2 was investigated under both dry and aqueous atmospheres through a fundamental density functional theory (DFT) study. Results showed that the CuFeS 2 (112) surface was the preferred cleavage surface, rather than the commonly-assumed (001) surface. Iron oxides were formed when contacting with either molecular O 2 or dissociated O atoms, but sulfoxy species were only formed in the presence of dissociated O atoms, exposing Cu atoms on the S-terminated (001) and (112) surfaces. This indicates that strong oxidation conditions are beneficial to CuFeS 2 oxidation and the release of metals into solution. In addition, CuFeS 2 was preferentially oxidized by O 2 prior to the adsorption of H 2 O under an aqueous condition with both H 2 O and O 2. The H 2 O adsorbed on the O-oxidized surface further promoted CuFeS 2 oxidation, resulting in the formation of a hydrophilic surface, rather than the naturally hydrophobic surface. This study has unveiled, for the first time, the mechanisms of the oxidation of the most stable and reactive CuFeS 2 (112) and (001) surfaces under both dry and aqueous environments at an atomic level, with potential applications in CuFeS 2 flotation and leaching processes. Unlabelled Image • CuFeS 2 (112) surface was the preferential cleavage surface, rather than (001) surface. • S 2 2- and S n 2- species were formed on CuFeS 2 surfaces during relaxation process. • O 2 was adsorbed on CuFeS 2 surfaces prior to the adsorption of H 2 O. • M-terminated CuFeS 2 surfaces, rather than the S-terminated, can be easily oxidized by molecular O 2. • H 2 O was necessary to form dissociated O atoms on chalcopyrite surface. [ABSTRACT FROM AUTHOR]

Abstract Fluorite, one of the major raw materials for fluoride in China, is mainly associated with sulfide and calcite minerals. The presence of these sulfide and calcite minerals cause the pipe blockage and efficiency loss during the production of anhydrous hydrofluoric acid (AHF). Worldwide, direct flotation techniques are utilized to beneficiate the fluorite into the chemical grades, but their separation efficiency remained limited due to similar flotability behaviors of fluorite, sulfide and calcite in fatty acid. In the present study, a novel method based on the acid leaching and reverse flotation has been envisaged for the purification and desulfurization of fluorite concentrates containing higher concentrations of sulfur and calcium. Leaching tests were performed by using hydrochloric acid, whereas the reverse flotation experiments were performed by using butyl xanthate as the collector and terpenic oil as the foaming agent. Leaching results showed that, calcite mineral dissolved and the fatty acid lost its collecting and foaming activities under the action of hydrochloric acid. The reverse flotation tests demonstrated that weight percent of sulfides, which are the main causes of blockage in AHF production, was substantially reduced from the fluorite concentrate. Interestingly, this method has been successfully implemented in Shizhuyuan fluorite dressing plant in China for the upgradation of fluorite concentrate. Calcite and sulfur contents of the concentrate were reduced from 4% to 0.01% and 0.5%–0.01%, respectively, and the grade of fluorite concentrate improved from 93.2% to more than 97% with a slight loss of fluorite. Furthermore, the safety in production of AHF was ensured with increased profit from the concentrator. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction (OER) is one of the core reaction modules of important renewable energy technologies with applications in water splitting, metal-air (oxygen) cells and regenerative fuel cells. However, OER catalysts are forced to operate with a significant intrinsic overpotential and inefficient charge transfer due to the adsorption energy scaling balance between the reaction intermediates. It is critical to develop an understanding of structure-activity relationship of catalysts, determine the speed control steps and improve catalytic activity. In this work, cobalt pentlandite (Co , Ni , Fe) 9 S 8 (CNFS) electrocatalysts were successfully prepared by combining the earth-abundant transition metal elements Co, Ni and Fe into a single structure. Benefiting from the structure, nanoflower morphology, and the synergistic effect among the three elements, the optimized sample requires an overpotential of only 335 mV to drive a current density of 50 mA cm–2 under alkaline conditions. The experimental results establish a composition-structure-function relationship, and the density functional theory results further indicate that the Fe sites bind more moderately to the intermediates and the electron synergistic effect occurs dynamically during the OER cycle reaction. This work not only provides a very promising catalyst candidate for efficient OER processes but also highlights the superiority of the cobalt pentlandite structure in the rational design of efficient OER electrocatalysts. • We synthesized natural mineral structures of cobalt pentlandite (Co,Ni,Fe) 9 S 8 structured OER catalysts. • Synergistic effect among the Co, Ni and Fe accelerates charge transfer and results in superior catalytic activity. • DFT calculations illustrate that the cobalt pentlandite (Co,Ni,Fe) 9 S 8 have an active OER site at the interface Fe site. [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]

In this paper, a novel macromolecular depressant polymaleamide-propyl dithiocarbamate (PMA-PDTC) was designed and synthesized according to density functional theory (DFT) calculations results, and its structure was characterized by infrared spectra (IR). The flotation experiments results demonstrated that PMA-PDTC was an effective depressant for galena in separating galena from chalcopyrite, and it exhibited a stronger depressing ability and a better selectivity for galena than for chalcopyrite. When the dosage of PMA-PDTC was 2.0 mg/L, a good separation result was obtained with O-isopropyl-N-ethyl thionocarbamate (IPETC) as collector at pH 8.5 for an artificial mixture of Cu-Pb minerals. The Cu concentrate could reach a grade of 28.89% containing 12.12% Pb, and the Pb concentrate could reach a grade of 80.65% containing 1.49% Cu. The experimental results agreed with the DFT calculations results well, which indicated that DFT method was useful for predicting the adsorption strength of some molecules on mineral surfaces and for guiding the design of the depressant for galena or other minerals. [ABSTRACT FROM AUTHOR]

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

[Display omitted] • The good affinity with water enables the strong hydroxylation of quartz surface. • The hydroxylated surface of quartz shows the nature of hydrophobicity. • The H-bonds between water molecules and hydroxylated surface is weaker than itself. The hydroxylation behavior of water on the quartz surface plays an important role in many fields. In this paper, the surface hydroxylation behavior of quartz and the molecular hydrophobicity of the hydroxylated surface were systematically studied by means of thermogravimetric analysis & differential scanning calorimetry (TGA-DSC), FTIR spectroscopy, and DFT calculations. TGA-DSC analysis showed that the complete desorption of structural water on the quartz surface needs to be carried out at 180.5 °C. FTIR spectra showed that the dehydrated sample had an obvious blue shift compared with the hydrated sample, suggesting that the hydrogen bonds on the surface of the dehydrated sample were weakened. The weakened hydrogen bonds are largely attributed to the partial desorption of water molecules in the hydroxyl hydration layer on quartz surface under vacuum at 130 °C, which is confirmed by DFT calculations. An interesting scientific discovery is that although quartz is highly hydrophilic and water molecules can be adsorbed on and hydroxylate the quartz surface, the hydroxylated surface is hydrophobic, and the secondary adsorption of water molecules on the hydroxylated surface is thermodynamically unfavorable. [ABSTRACT FROM AUTHOR]

[Display omitted] • PFS is an effective adsorbent for removal COD. • The treated SFW could be reused in scheelite-flotation system. • Amorphous Fe(OH) 3(s) reacted with oleate to the formation of iron carboxylate. • The COD removal mechanism of PFS was deduced and described. This study investigated an efficient method for removal COD of scheelite flotation wastewater (SFW) with polyferric sulfate (PFS) and the reuse of the treated water into the flotation system. The mechanism of COD removal was studied by scanning electronmicroscopy coupled with energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transforminfrared spectroscopy, species distribution calculation and kinetics. Results showed that 66.85 % COD removal was achieved with PFS treatment under the optimum conditions (Contact time: 30 min, PFS dose: 1.5 g/L, and initial solution pH: 8). The COD of SFW was reduced from 207.36 mg/L to 68.75 mg/L and the COD removal capacity could reach 92.41 mg/g. The treated SFW could be reused in scheelite-flotation system without affecting index of scheelite. In addition, amorphous ferric hydroxide (Fe(OH) 3(s)) was formed during Fe(III) hydrolysis, and it could reacted with oleate to the formation of iron carboxylate, resulting the removal of COD in SFW. The kinetic analysis of PFS treatment process showed that the removal of COD obeyed the pseudo-second-order kinetic model, and the main rate-limiting step of the adsorption of amorphous Fe(OH) 3(s) was chemisorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • TMA was first explored as a chalcopyrite depressant in Cu-Mo flotation separation. • TMA could realize the effective separation of Cu-Mo artificially mixed minerals. • TMA could effectively reduce the contact angle of chalcopyrite. • TMA was likely to chemisorb on chalcopyrite by FT-IR and XPS analysis. In this study, N-thiourea-maleamic acid (TMA) was first introduced as a chalcopyrite depressant in flotation separation of Cu-Mo sulfide ores. The effects of TMA on the separation of Cu-Mo were investigated by micro-flotation tests. The results indicated that TMA was beneficial to separate chalcopyrite and molybdenite in the flotation separation of artificially mixed minerals at pH around 9.0 with a Mo recovery of 95.56% and depressing 94.64% of Cu. Its adsorption mechanism was revealed by contact angle, UV–Vis spectra, FT-IR and XPS measurements, in which, the contact angle and UV–Vis spectra measurements further proved that TMA did adsorb on chalcopyrite surface. Moreover, FT-IR and XPS measurements demonstrated that S atoms in the thiourea group of TMA interacted with Cu sites on chalcopyrite surface. All these findings confirmed that TMA would be a highly effective chalcopyrite depressant. TMA could adsorb onto chalcopyrite surface thereby increase its hydrophilicity without significant influence on molybdenite. [ABSTRACT FROM AUTHOR]

[Display omitted] • The adsorption of collectors and ilmenite involves the hybrid of O 2p and Ti 3d. • Arsenic and phosphorous acids are the most efficient collectors of ilmenite. • This work is instructive to design efficient flotation collectors for ilmenite. Flotation is the main method to purify ilmenite, the success of flotation is closely related to the effective adsorption of collectors on the mineral surface. Herein, the coordination chemistry adsorption mechanism of the commonly used collectors with oxygen-containing functional groups on ilmenite surface were systematically investigated by first-principles DFT calculations. Adsorption energy results shows that the O bearing pnictogen compounds are the best for ilmenite beneficiation among all the oxygen-containing collectors. In the O-bearing pnictogen compounds, the collection performance of arsenic acid is the best, followed by phosphorous acid and phosphoric acid ester. The frontier molecular orbital analysis predicted that the collectors possessed a good chemical bonding ability with ilmenite, which is confirmed by the charge population analysis that there is significant electron transfer (bonding evidence) between collectors and ilmenite. Partial density of states analysis further confirmed that the physicochemical nature of the adsorption of the collectors on the surface Ti site were ascribed to the hybridization of O 2p and Ti 3d, in which the O 2p electrons of the collectors occupied the empty orbital of Ti 3d to complete the coordination shell of surface Ti atom. This work sheds new light on the screening of solidophilic functional groups for the collector design of ilmenite beneficiation and helps to explain the adsorption mechanism of oxygen-containing collectors on the oxidized mineral surface. [ABSTRACT FROM AUTHOR]

[Display omitted] We employed computational density functional theory (DFT) and microflotation tests complemented by analysis of electronic properties and X-ray photoelectron spectroscopy (XPS) data to investigate the adsorption mechanism of O-isopropyl-N-ethyl-thionocarbamate (IPETC), O-isopropyl-N-diethyl-thionocarbamate (IPDETC) and S-allyl-N-diethyl-dithiocarbamate (ADEDTC) on chalcopyrite reconstructed-(1 1 2) surface and pyrite (1 0 0) surface. The adsorption of the thiocarbamate collectors on chalcopyrite was observed to preferentially occur at Cu atoms instead of Fe atoms. The thiocarbamate collector adsorption on chalcopyrite Cu sites decreased in the order ADEDTC > IPDETC > IPETC, while on pyrite Fe sites, the adsorption strength decreased in the order ADEDTC > IPETC > IPDETC. This shows that the adsorption of ADEDTC was strong, although the adsorption on pyrite was weaker than the adsorption on chalcopyrite. In the associated microflotation tests, the chalcopyrite recoveries exceeded 90%, while the pyrite recoveries reached only 25%, with ADEDTC exhibiting the highest recoveries. XPS analysis of chalcopyrite treated and not with ADEDTC revealed that the adsorption of the ADEDTC S1 atom was stronger at Cu sites than at Fe sites. These findings provide a clear correlation between experiments and DFT predictions and therefore suggest that these thiocarbamate collectors may be useful in the floatation separation of chalcopyrite from pyrite minerals. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel polymer depressant DTC-PAA was synthesized and used as galena depressant. • DTC-PAA showed excellent depressing performance on galena at pH 8.5. • Chalcopyrite was separated effectively from galena in the presence of DTC-PAA. • DTC-PAA chemisorbed on galena surface via dithiocarbamate groups and Pb sites. In this research, to achieve green effective separation of chalcopyrite and galena, a novel synthetic depressant, dithiocarbamated poly(acrylamide-allyamine) (DTC-PAA), was prepared and innovatively employed as a galena depressant. The flotation behaviours of chalcopyrite and galena were investigated by micro-flotation experiments in the absence and presence of DTC-PAA depressant comparing with potassium dichromate with O-isopropyl-N-ethyl thiocarbamate (IPETC) as the collector. The micro-flotation results showed that DTC-PAA was an effective depressant for galena in the flotation separation from chalcopyrite when using IPETC collector. Their adsorption mechanisms were unravelled by FT-IR, zeta potential, adsorption capacity measurement, XPS and DFT calculations. The results of adsorption capacity tests showed that DTC-PAA prevented the adsorption of IPETC collector on galena surface. However, DTC-PAA could not prevent IPETC from adsorbing on chalcopyrite surface. It was found that DTC-PAA depressant could chemisorb onto Pb sites of galena surface through dithiocarbamate groups in DTC-PAA. These findings were also supported by FT-IR, zeta potential, XPS analysis and DFT calculations results. It implied that DTC-PAA might be a promising alternative of the potassium dichromate depressant in the flotation separation of Cu-Pb ores. [ABSTRACT FROM AUTHOR]

[Display omitted] • A PADEMA polymer depressant was first designed, synthesized and characterized. • Its interfacial adsorption mechanism on galena was further revealed by AFM, XPS and ToF-SIMS. • PADEMA could chemisorb on galena surface via the dithiocarbamate groups and Pb sites. • PADEMA could selectively depress galena and achieve the flotation separation from chalcopyrite. In mineral processing, a chemical with hydrophilic groups and mineral-avid groups together might be used as a depressant to depress target minerals. In the present study, a novel polymer depressant poly(acrylamide-2-(dithiocarbamate) ethyl maleamidic acid) (PADEMA) containing amide groups as hydrophilic groups and dithiocarbamate groups as mineral-avid groups, was first designed, synthesized and used to depress galena in the flotation separation from chalcopyrite. Its selective interfacial adsorption mechanism on galena surface was comprehensively investigated by Fourier transform infrared spectroscopy (FT-IR), adsorption capacity tests, contact angle, Atomic Force Microscope (AFM), X-ray photoelectron spectroscopy (XPS) measurements and time-of-flight secondary ion mass spectrometry (ToF-SIMS). These analysis results demonstrated that PADEMA was likely to chemisorb on galena surface by forming a polymer complex via Pb sites on galena surface and the dithiocarbamate groups in PADEMA structure. The micro-flotation separation results indicated that the PADEMA polymer depressant could adsorb on galena surface and render it hydrophilic, thus to improve the separation index during the flotation separation of chalcopyrite and galena. [ABSTRACT FROM AUTHOR]

• A methodology of foam ceramics based on full-tailings is presented. • The auxiliary foaming effect of tailings greatly reduces the dosage of foaming agent. • The foam ceramics with excellent properties can be used as construction material. • This technology can bring considerable environmental and economic benefits. In the system of CaO-Al 2 O 3 -SiO 2 phase diagram, using vanadium-titanium magnetite tailings (VTMT), feldspar tailings (FT), and kaolinite-type pyrite tailings (KTPT) as raw materials, the foam ceramics have been prepared by introducing SiC as foaming agents. Based on X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry analysis (TG-DSC), scanning electron microscopy (SEM), and properties experiments, the effects of raw materials content and sintering temperature on crystalline phase composition, structure, and properties of foam ceramics are comprehensively investigated. In particular, the auxiliary foaming effect of VTMT, which is the reason for the low usage of foaming agent, is explicated. The sample prepared with 60 wt% of VTMT and sintered at 1140℃ possessed porosity of 79.48%, bulk density of 0.314 g/cm3, and compressive strength of 3.81 MPa, respectively. This study realizes the comprehensive utilization of VTMT, FT, and KTPT, and at the same time provides an idea for full tailings-based foam ceramics with low cost. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanomaterials are highly efficient in the recovery of precious metals (PMs). • Inorganic nanoparticles always act as the substrate for further modification. • Developing organic polymer-support nanocomposites is a promising strategy. • Metal-organic frameworks (MOFs) display outstanding adsorption performance for PMs. • Physical adsorption and chemical interaction have crosstalk in PMs recovery. The efficient recovery of precious metals (PMs) from aqueous solution or wastewater is a hot issue from both economic and environmental perspectives. In the past few years, nanomaterials have been applied in the capture and isolation of PM ions due to their unique physical and chemical properties, including large surface area (up to ∼ 14,600 m2‧g−1), high reactivity, and developed porosity. Hereby, we systematically review the progress and advances in the field of PM adsorption by nanomaterials such as metal oxide/sulfide nanoparticles, graphene, silica gel, nanocellulose, chitosan-support nanomaterials, and metal–organic frameworks (MOFs) etc. In this review, nano adsorbents are categorized as inorganic nanomaterials, organic polymer-support nano composites, and MOFs. The reported maximum adsorption capacity of Au (III) was 4262.8 mg‧g−1 by TU*ZIF-8, which exhibited great superiority to other nano adsorbents. Mechanisms associated with PM adsorption by nano adsorbents including physical adsorption (i.e. electrostatic interaction, diffusion) and chemical adsorption (i.e. coordination, chemical bonding, ion exchange, acid-base interaction, and reduction) are comprehensively summarized and discussed. Normally, the adsorption of PMs by nanomaterials is a complicated process involving more than one mechanism. In the future, more efforts are still needed to promote the large-scale and industrial-scale application of nano adsorbents in PM recycling. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbamates from known IBECTC, BBCTC IBBCTC to DFT predicted BECTC, IBIBCTC (84/85) • S1 carbamates atoms react with Cu chalcopyrite atoms to form covalent bonding. (82/85) • DFT and µ-flotation show similar ranking: BBCTC > IBIBCTC > BECTC > IBBCTC > IBECTC (84/85) • Straight carbon chains are better in performance than branched ones on chalcopyrite (85/85) • DFT predicts chalcopyrite recovery by thiocarbamates reliably (64/84) First-principle quantum mechanical density functional theory (DFT) was employed to explore the bonding behaviour, adsorption energies and electronic properties directly related to the reactivity's of O-butyl-N-ethoxycarbonyl-thiocarbamate (BECTC), O-isobutyl-N-ethoxycarbonyl-thiocarbamate (IBECTC), O-butyl-N-butoxycarbonyl-thiocarbamate (BBCTC), O-isobutyl-N-butoxycarbonyl-thiocarbamate (IBBCTC), and O-isobutyl-N-isobutoxycarbonyl-thiocarbamate (IBIBCTC) with the chalcopyrite (CuFeS 2) (1 1 2) surface and complimented by micro-flotation recoveries of the chalcopyrite. The partial density of states (PDOS) of the isolated oxycarbonyl-thiocarbamate collector showed that the sulphur atom (S1) was more active and will be more reactive during adsorption. Adsorption of the oxycarbonyl-thiocarbamate collectors preferred the Cu atom over Fe atoms. The adsorption energies and micro-flotation recoveries yielded similar trends and the order followed: BBCTC > IBIBCTC > BECTC > IBBCTC > IBECTC, which showed that BBCTC exhibited the strongest exothermic adsorption. This showed that the adsorption energies that determined how a collector binds to the mineral surface can predict the flotation recoveries. The PDOS and atomic population charges after adsorption showed that both Cu and S1 atoms lose charges (electron donor) forming σ-bonds, and simultaneously, dative π-bonds. The results also showed that BBCTC and BECTC are better collectors for the selective flotation of chalcopyrite minerals and indicated that a straight hydrocarbon chain gave stronger adsorption than a branched hydrocarbon chain. [ABSTRACT FROM AUTHOR]

In this study, a novel organic depressant maleyl 5-amino-1,3,4-thiadiazole-2-thiol (MATT) was synthesized and utilized as a galena depressant in the flotation separation of molybdenite and galena. The results of the flotation test indicated that MATT exhibited an excellent depression ability on galena but barely influenced the flotation of molybdenite in the pH range of 6.0–11.0. Zeta potential results suggested that MATT preferentially adsorbed on galena surface. UV-visible spectroscopy analysis indicated that the stoichiometric ratio of lead ion and reagent in the complex compound. XPS analysis demonstrated that the S (-SH) atom and N (1,3,4-thiadiazole group) atom of MATT coordinated with the Pb atom on galena surface. [ABSTRACT FROM AUTHOR]

• Ferric ions have inhibitory effect on flotation of bastnaesite. • Ferric ions are adsorbed with RE ions on bastnaesite surface. • The interaction between ferric ions and RE ions through bidentate adsorption. • The interaction mechanism between bastnaesite, ferric ions and H205 was studied. In the system of 3-hydroxy-2-naphthyl hydroxamic acid (H205) collector, the adsorption of ferric ions on the surface of bastnaesite and its significance in flotation was investigated by micro-flotation tests, zeta potential measurements, adsorption experiments, solution chemistry analysis, X-ray photoelectron spectroscopy (XPS) measurements and density functional theory (DFT) calculations. From the results of our experiments, it can be known that ferric ions species (Fe(OH) 3(s)) can absorb on the surface of bastnaesite by interacting with RE(OH) x 3−x (x = 1, 2) (RE = Ce, La and Nd) to form RE-O-Fe-OH. And in this process, Fe(OH) 3(s) is bound to RE(OH) x 3−x (x = 1, 2) mainly by bidentate adsorption. By bidentate adsorption with RE(OH) x 3−x (x = 1, 2), the addition of ferric ions decreases adsorption sites for H205, impedes the adsorption of H205 on the surface of bastnaesite, and then depresses bastnaesite flotation. [ABSTRACT FROM AUTHOR]

• A macromolecule PAM-ATU was employed as a galena depressant. • PAM-ATU could realize the separation of molybdenite from galena at pH around 10.5. • PAM-ATU could adsorb on galena surface via chemisorption by FT-IR and XPS analysis. In the present research, a macromolecular depressant poly(acrylamide-allylthiourea) (PAM-ATU) was explored to depress galena in the flotation separation from molybdenite. Its flotation behavior was evaluated by micro-flotation tests. The micro-flotation results revealed that PAM-ATU could depress galena strongly at 4.0 mg/L within pH 6.0–12.0, while molybdenite was found sensitive to the pH. At pH around 10.5, molybdenite showed a relatively good floatability with a nearly 80.0% recovery in the presence of 4.0 mg/L PAM-ATU. The flotation separation results for artificially mixed minerals proved that 1.0 mg/L PAM-ATU could selectively depress galena well. FT-IR and XPS analysis results demonstrated that PAM-ATU was likely to adsorb on galena surface by chemisorption. This study indicated that the synthesized PAM-ATU with low molecular weight might be a promising galena depressant in the flotation separation of Mo/Pb ores. [ABSTRACT FROM AUTHOR]

The effects of six kinds of carboxyl collectors with different structures on the flotation behaviors of smithsonite have been studied by theoretical and experimental methods. Micro-flotation experiment suggested that with the increase of carbon chains length and double bonds, the flotation recovery increased. Linoleic acid and oleic acid showed great collectivity and naphthenic acid hardly floated smithsonite. DFT calculation results suggested benzenoid and saturated carboxyl collectors exhibited small electrophilicity and unsaturated carboxyl collectors possessed large electrophilicity. Water molecules had a great impact on the adsorption of carboxyl collectors on smithsonite surface. In the absence of water molecules, the simulation result of carboxyl collector adsorption was inconsistent with the flotation experiment. In the presence of water molecules, only oleic acid and linoleic acid showed great collecting power to smithsonite, which coincides well with the experiment results. It was found that adsorption of water weakend the hybridization of 3s and 3p orbitals and electrophilicity of surface Zn atom, and thus unfavorable for the adsorption of carboxyl collector with small electrophilicity. The results could provide a theoretical guidance for the design of an effective collector of zinc oxide flotation. • Carboxyl collectors with different structure are studied in smithsonite flotation. • Structure of carboxyl collector affects its nucleophilicity and electrophilicity. • Carboxyl collectors with double bonds show great collecting power to smithsonite. • Water can reduce s and p orbitals hybridization and electrophilicity of Zn atom. [ABSTRACT FROM AUTHOR]

Through industrial testing at the Huize lead-zinc mine, it was found that the floatability of sphalerite varied greatly with the iron impurity content. Three kinds of Huize sphalerites with iron contents of 2.30 wt.%, 3.20 wt.% and 4.66 wt.%, were used to study the influence of small amounts of iron impurity in the sphalerite on xanthate adsorption and flotation behavior. The flotation experiments showed that the flotation recovery increased with the increase in iron impurity content. Fourier Transform infrared spectroscopy (FTIR) and Ultraviolet–visible (UV-VIS) spectra showed that the adsorbed products of xanthate on the surface of three kinds of sphalerite were metal xanthate. The adsorption capacity measurements showed that the saturation absorption of xanthate on sphalerite increased with the increase in iron impurity content. The cyclic voltammetry curve and Tafel curve showed that with the increase in iron impurity content, sphalerite was more easily oxidized and the adsorption rate of xanthate on the surface of sphalerite increased obviously. To summarize, a small amount of iron impurity was beneficial to the recovery of sphalerite. [ABSTRACT FROM AUTHOR]

Mechanical activation has been applied prior to leaching to improve copper extraction from chalcopyrite. Results showed that 86% copper was extracted within 2 h from chalcopyrite ground with sodium chlorite at 500 rpm, at pH 1.0 (sulfuric acid) and 348 K, greater than from leaching of unground (4.5% copper extraction) and ground chalcopyrite without sodium chlorite (13.5% extraction). Size reduction, structural modification and phase transformation were suggested as three mechanisms for improved copper extraction rate, with the last mechanism found to be dominant. Two leaching steps were proposed, for the first time, for chalcopyrite ground with sodium chlorite, including the first stage primarily determined by the dissolution of copper chlorite formed via a solid state reaction during grinding with chalcopyrite and the second stage dominated by the dissolution of unconverted chalcopyrite. This study suggests that grinding of chalcopyrite with sodium chlorite is beneficial to highly efficient copper extraction from chalcopyrite. Unlabelled Image • Cu extraction from CuFeS 2 was increased from 4.5% to 86% after grinding with NaClO 2 ; • CuFeS 2 co-ground with NaClO 2 produced water soluble CuCl 2 ; • Two leaching stages were proposed for CuFeS 2 co-ground with NaClO 2 ; • Three activation mechanisms were clearly identified for CuFeS 2 co-ground with NaClO 2. [ABSTRACT FROM AUTHOR]

• Chalcopyrite flotation recovery was significantly decreased in sea water, primarily due to Mg2+. • Sodium silicate improved chalcopyrite flotation in sea water and MgCl 2 solution, but insignificantly in pure water. • SS adsorbed on Mg(OH) 2 surface, preventing Mg(OH) 2 adsorption on chalcopyrite surface. • Electrostatic interaction played an important role in reversing forces between chalcopyrite and Mg(OH) 2. Due to the shortage of fresh water, sea water has been considered as a promising alternative for mineral flotation. Sodium silicate (SS) was used to eliminate the negative influence due to the application of sea water for chalcopyrite flotation and the related mechanisms were studied. Flotation results showed that the most detrimental compound in sea water was the divalent ion of Mg2+. Contact angle measurements suggested that SS increased chalcopyrite hydrophobicity in sea water and MgCl 2 solution. The zeta potential of chalcopyrite became more negative while that of Mg(OH) 2 was reversed from positive to negative upon the addition of SS, preventing the adsorption of hydrophilic Mg(OH) 2 precipitates on chalcopyrite surface. FTIR and XPS analyses further confirmed that the presence of SS in sea water reduced the adsorption of Mg(OH) 2 on chalcopyrite surface. In addition, Derjguin-Landau-Verwey-Overbeek (DLVO) calculation indicated that SS can prevent the adsorption of Mg(OH) 2 on chalcopyrite surface, thereby increasing chalcopyrite recovery. Therefore, this study presents an effective method to improve chalcopyrite flotation recovery in sea water. [ABSTRACT FROM AUTHOR]