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Hydration of MgO is a potential technology for economically preparing Mg(OH)2 slurry. Understanding the rheological behavior evolution of the slurry during MgO hydration, particularly in the presence of hydration agent, is essential for better control of the hydrated Mg(OH)2 slurry's rheology. In this work, Mg(OH)2 slurry was prepared by hydrating MgO in the presence of glycine. The effect of glycine on the rheological behavior of the hydrated Mg(OH)2 slurry have been investigated by means of viscosity, shear stress, sedimentation measurements, particle size distribution, 1H nuclear magnetic resonance relaxometry and zeta potential. Results showed that shear thinning rheological slurry could be made by hydration at 80 °C for 1 h. The yield stress of the slurry is 27.49 ± 0.81 Pa, and no settling occurs within 7 days. Yet, in the absence of glycine, the structure of the slurry was unstable and easily settled even after 8 h of hydration. Glycine has multiple effects on the slurry's solid loading, particle morphology, particle size distribution, and zeta potential of the slurry. In addition, the neutral zwitterionic form of glycine may serve as an inter-particle lubricant, reducing viscosity. [ABSTRACT FROM AUTHOR]

A novel collector, 2-carboxyethylphenylphosphinic acid (CEPPA), was first used in the flotation of cassiterite. The flotation performances and the adsorption mechanism of CEPPA on cassiterite were investigated by flotation tests, adsorption experiments, zeta potential measurements, Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. The results indicated that CEPPA had strong collecting power for cassiterite and fluorite over a wide pH range but little on quartz. In the separation of the cassiterite–quartz mixture, a concentrate containing 90.9% SnO2 was obtained with a recovery of 95.7% at pH 7.0. The cassiterite in the cassiterite–fluorite mixture could be effectively separated using 300 mg/L sodium silicate in conjunction with 60 mg/L CEPPA, and a concentrate with a grade of 90.3% SnO2 and a recovery of 92.6% was achieved at neutral pH. Zeta potential analysis demonstrated that the adsorption process involved both physical and specific forces. The results of FTIR and XPS further suggested that the four O atoms of CEPPA reacted with the Sn atoms on cassiterite surface, forming a complex which was similar to the Sn–CEPPA precipitate, and hydrogen bonding adsorption could have taken place between the terminal hydroxyl groups and CEPPA anions. [ABSTRACT FROM AUTHOR]

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

Bromine atom with strong electronegativity was introduced to α-carbon position of lauric acid (LA) by solvent-free method (Hell–Volhard–Zelinski reaction) at ambient pressure in laboratory, and the synthesized product α-Bromolauric acid (CH 3 (CH 2 ) 9 CHBrCOOH, α-BLA) was used as a new type collector for the flotation of quartz mineral. The flotation properties of pure quartz using α-BLA as a collector were investigated by single mineral flotation tests. The adsorption mechanism of α-BLA collector on quartz surface was established by zeta potential measurements, Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS), in conjunction with the results of quartz micro-flotation tests. Pure mineral flotation results showed that the collector α-BLA exhibited an excellent performance at alkaline conditions (pH ⩾ 11.50), activator CaCl 2 concentration 1.0 × 10 −4 mol/L, and collector concentration 1.5 × 10 −4 mol/L in a relatively lower temperature 15 °C, where about 99.8% of the quartz could be floated out. Compared with collector LA, the new synthesized collector α-BLA is more tolerant to lower pulp temperature and fluctuations of the reagents dosages. The study revealed that the α-BLA collector had adsorbed on the surface of pure quartz in the forms of chemical interaction, electrostatic adsorption and hydrogen bonding adsorption based on the results of zeta potential measurements, FT-IR spectra, and XPS. [ABSTRACT FROM AUTHOR]

[Display omitted] • Curdlan was a clean and efficient polysaccharide depressant of hematite. • Curdlan could selectively depress hematite and had a weak dispersion effect on quartz, which made it more selective. • Curdlan was selectively adsorbed on hematite through chemical bonds between hydroxyl and iron atoms. In this study, the quartz-hematite reverse flotation separation was realized by using curdlan to selectively depress hematite. The behavior of curdlan on quartz-hematite reverse flotation separation was researched by micro-flotation tests. And, its depression mechanism on the hematite was researched with zeta-potential measurements, turbidity measurements, FT-IR and XPS analyses. It can be seen from the results of micro-flotation tests that curdlan could reduce the floatability of hematite without affecting quartz. The grade of iron concentrate improved to 65.03% (Recovery was 90.03%), at pH 11.5 and concentration of curdlan 20 mg/L. Turbidity tests showed that curdlan-treated hematite flocculated in the pulp, while curdlan-treated quartz dispersed in the pulp. This was due to the adsorption of curdlan on hematite surface (i.e., the bridging of reagents) overcame the electrostatic repulsion between hematite particles. Zeta potential results showed that curdlan was adsorbed strongly non-electrostatically to the surface of hematite, but weakly adsorbed to quartz. FT-IR analyses showed that curdlan adsorbed on the hematite surface first, which hindered the subsequent adsorption of NaOl and Ca2+ on the surface of hematite. However, no characteristic peaks of curdlan were found on the surface of the quartz, and the quartz treated by curdlan and Ca2+ could still adsorb NaOl. XPS analyses demonstrated further that curdlan was chemically bonded to Fe sites on the hematite surface through its hydroxyl group. [ABSTRACT FROM AUTHOR]

Reverse cationic flotation is an important method for iron ore flotation. In this process, it is particularly important to find efficient, environmentally friendly and inexpensive hematite depressants. Hydrolyzed polyacrylamide (HPAM), an inexpensive and environmentally friendly synthetic polymer organic reagent, was studied for the first time in this field. In this paper, the separation effect of HPAM on hematite and quartz in ether amine system was evaluated by flotation tests of single minerals and artificial mixed ore. The hydrophilicity of the two minerals in different chemical environments was verified by contact angle measurement. The adsorption and depression mechanism of HPAM on the two minerals was studied by surface adsorption tests, zeta potential measurements, FT-IR analysis and XPS analysis. The flotation results showed that under the conditions of 100 mg/L HPAM and 7.5 mg/L EA at pH 11, the hematite recovery was 84.46%. The contact angle analysis showed that the addition of HPAM increased the hydrophilicity difference between hematite and quartz. Surface adsorption test results showed that the adsorption capacity of HPAM on hematite was much larger than that on quartz. Zeta potential measurements, FT-IR analysis and XPS analysis confirmed that HPAM was selectively adsorbed on the surface of hematite. The adsorption of HPAM on the surface of hematite mainly occurred through strengthening chemical adsorption and hydrogen bond adsorption. [Display omitted] [ABSTRACT FROM AUTHOR]

• A new collector α-BDDA was used to separate spodumene from feldspar and quartz. • Spodumene, feldspar and quartz recovery was 83.44%, 7.83% and 1.38% respectively. • A concentrate with recovery of 75.57% and Li 2 O grade of 5.77% was obtained. • Ca was the main active site on activated spodumene to react with α-BDDA. • Conjugated effect existed among the O atom on spodumene, Ca2+ and O atom of α-BDDA. The flotation behaviors of α-bromododecanoic acid (α-BDDA) on the separation of spodumene from feldspar and quartz with Ca(II) as activator were investigated through single mineral and artificial mixed ore flotation experiments. Under the condition of α-BDDA concentration of 1.79 mmol/L, Ca(II) concentration of 0.51 mmol/L and pH 7.1, the recovery of spodumene, feldspar and quartz was 83.44%, 7.83% and 1.38% respectively in single mineral flotation experiments, and a concentrate with recovery of 75.57% and Li 2 O grade of 5.77% was obtained in a ternary mixed ore (Li 2 O grade of 1.71%) flotation experiment. AFM, zeta potential measurements, FT-IR, XPS, species distribution and first-principles calculation were carried out to analyze the interaction mechanism between the reagents and the minerals. It was found that the amounts of α-BDDA adsorbed on spodumene were much higher than those on feldspar or quartz, which led to the higher recovery of spodumene. The main component of Ca(II) at pH 7.1 was Ca2+, which was adsorbed on spodumene, feldspar and quartz by both electrostatic attraction and chemical bond. The collector α-BDDA was adsorbed on Ca2+ activated spodumene, feldspar and quartz by chemisorption. Ca on the surface of the activated spodumene was the main active site to react with α-BDDA. In the presence of α-BDDA, the bond length of O spodumene — Ca increased and was close to that of O α-BDDA — Ca, indicating the conjugated effect among the O atom on spodumene, Ca2+ and the O atom in α-BDDA. The collector α-BDDA was an effective spodumene collector with high selectivity, which could effectively separate spodumene from feldspar and quartz. [ABSTRACT FROM AUTHOR]

• A new collector PPPDA was synthesized in laboratory. • Spodumene, feldspar and quartz recovery were 5.39%, 89.31% and 91.7% respectively. • PPPDA had the potential to be a collector in reverse flotation of crude concentrate. • PPPDA was adsorbed on the minerals by both electrostatic attraction and hydrogen bond. • The "Spatial Matching Effect" might lead to different adsorption models. A new collector N-{3-[(2-propylheptyl)oxy]propyl}propane-1,3-diamine (PPPDA) was successfully synthesized in laboratory. The flotation behaviors of PPPDA on the separation of spodumene from feldspar and quartz were investigated through single mineral flotation experiments. The effects of pH, PPPDA concentration, metal ions concentration and the adding sequence of these reagents during the separation process were evaluated. At the condition of PPPDA concentration of 0.171 mmol/L, Ca(II) concentration of 0.171 mmol/L and pH 5.2, the greatest difference of recovery between spodumene and the gangues (feldspar and quartz) was achieved. The recovery of spodumene, feldspar and quartz under this condition was 5.39%, 89.31% and 91.7% respectively, which indicated that PPPDA had the potential to be used as a collector in reverse flotation of crude concentrate. The adsorption mechanism was investigated systematically by zeta potential, FT-IR, AFM, and adsorption amount measurements. The results demonstrated that PPPDA could be adsorbed on spodumene, feldspar and quartz through both electrostatic attraction and hydrogen bond. The amounts of PPPDA adsorbed on feldspar or quartz were much more than those on spodumene, which led to higher recovery for feldspar and quartz. The difference of the distance between the two nitrogen atoms in PPPDA and the distance between the two oxygen atoms on mineral surfaces, that is the "Spatial Matching Effect", might lead to different adsorption models. Furthermore, in the presence of Ca(II), there was the competitive adsorption between Ca(II) and PPPDA. The spodumene preferred to adsorb Ca(II), while feldspar and quartz preferred to adsorb PPPDA. Therefore, Ca(II) could expand the floating difference of spodumene from feldspar and quartz with PPPDA as the collector. [ABSTRACT FROM AUTHOR]

Low flotation recovery, high pulp temperature, and large dosage of reagents are the typical disadvantages when using mixed fatty acids (MFA) prepared from hogwash oil for flotation directly. To determine the type of fatty acid that yields poor flotation performance, flotation performance and adsorption characteristics of saturated fatty acids (SFA) and unsaturated fatty acids (UFA) separated from the MFA were studied in our work. GC-MS, FT-IR, iodine value detection and melting point measurement showed that UFA contained –(CH=CH–CH2)n- groups and had much lower melting point. Quartz flotation tests were used to compare the flotation performance of UFA and SFA, which showed that UFA had excellent low-temperature floatability, and the flotation recovery of UFA was 35 percentage points higher than that of SFA at 20 °C and pH = 11.5. Zeta potential, FT-IR and XPS analysis indicated that UFA and SFA could adsorb onto the surface of activated quartz through chemisorption and hydrogen bonding. However, the adsorption of UFA was much stronger and more favorable; thus, the reason MFA have poor flotation performance was the presence of SFA. [ABSTRACT FROM AUTHOR]

• A mixture of Hexyloxypropylamine (HPA) and N-Dodecyliminodiacetic acid (DIDA) was the first time used to separate spodumene from feldspar. • A greater difference of recovery of spodumene and feldspar was achieved. • Chemisorption and hydrogen bonds adsorption was the main adsorption mechanism of HPA/DIDA on spodumene. • The distinction of Al sites and O sites on spodumene and feldspar surface accounted for the selectivity of HPA/DIDA. New collectors, hexyloxypropylamine (HPA) and N-Dodecyliminodiacetic acid (DIDA) were synthesized in laboratory. The flotation behavior of both collectors on spodumene and feldspar was investigated by micro-flotation tests respectively. A new mixed collector HPA/DIDA was prepared in order to achieve a greater difference of recovery of spodumene and feldspar. Through micro-flotation tests, the flotation behavior of HPA/DIDA on spodumene and feldspar was evaluated. The test results showed that the recovery of spodumene and feldspar was 85.61% and 7.38% respectively under the optimal conditions that the mass ratio of HPA:DIDA was 1:3; HPA/DIDA concentration was at 57.14 mg/L; and the pulp had no pH regulator added. The adsorption mechanism of the collector on spodumene and feldspar surface was established by zeta potential, FT-IR, XPS and surface tension measurements. It was found that HPA was adsorbed on spodumene surface mainly through hydrogen bonds adsorption, then adsorbed on feldspar by electrostatic adsorption. DIDA was adsorbed on spodumene and feldspar surface by chemisorption. While the mixed collector HPA/DIDA was self-assembled to HPA-DIDA complex and got adsorbed on spodumene surface by synergistic effect of chemisorption and hydrogen bonds adsorption, it was adsorbed on feldspar surface only by chemisorption. The difference of Al sites and O sites between spodumene (110) surface and feldspar (010) surface accounted for the selectivity of HPA/DIDA. The coexistence of ―COOH and ―NH 2 facilitated the adsorption of HPA/DIDA on spodumene, but it obstructed the adsorption of HPA/DIDA on feldspar, which led to the great recovery disparity of spodumene and feldspar. [ABSTRACT FROM AUTHOR]

• A new complex DPA-BDDA was prepared by decyloxy-propyl-amine (DPA) and α-bromododecanoic acid (α-BDDA) • Supramolecular complex was first time used to separate spodumene from feldspar. • A great difference of recovery of spodumene and feldspar was achieved. • The adsorption mechanism of the collector on spodumene was chemisorption and electrostatic attraction. A new complex DPA-BDDA was prepared by decyloxy-propyl-amine (DPA) and α-bromododecanoic acid (α-BDDA) as a collector in the flotation of spodumene and feldspar respectively. The flotation was investigated under different conditions. In particular, molar ratio of DPA: α-BDDA, the optimum pH, and DPA-BDDA dosage were studied. It was found that the greatest difference of recovery (spodumene 82.14% and feldspar 32.48%) occurred by using 14.28 mg/L of DPA-BDDA (molar ratio of DPA: α-BDDA 1:1) at pH of 4.48. The flotation adsorption mechanism of DPA-BDDA on spodumene and feldspar surface was searched by DLS, FT-IR, XPS and zeta potential measurements. The FT-IR results indicated that there was halogen bond effect between DPA and α-BDDA, which demonstrated that the DPA and α-BDDA were formed supermolecules. Although the active sites on broken surfaces of spodumene and feldspar were Al and O sites, the type and the number of Al and O sites per unit area on spodumene and feldspar were different, which might lead to the difference of surface chemistry features of spodumene and feldspar. The XPS results indicated that the quantity of DPA-BDDA adsorbed on spodumene surface was higher than that on feldspar surface. The results also revealed that DPA-BDDA was adsorbed on spodumene surface through both electrostatic attraction and chemisorption. In addition, the electrostatic attraction between NH 3 + and spodumene negative surface reduced the electrostatic repulsion between COO− and spodumene surface, which facilitated the adsorption of DPA-BDDA on spodumene. However, since the more negative surface of feldspar, the steric hindrance effect and less Al sites on feldspar surface, the DPA-BDDA was adsorbed on feldspar mainly by electrostatic attraction. [ABSTRACT FROM AUTHOR]

[Display omitted] • HCA could selectively separate cassiterite from fluorite with CEPPA as a collector. • Interaction between CEPPA and cassiterite barely affected by weak adsorption of HCA. • Ca sites exposed on fluorite had a stronger affinity for HCA than cassiterite. • Significant adsorption of HCA on fluorite hinders adsorption of CEPPA. As an essential raw material for the tin industry, cassiterite ore needs to be effectively separated and purified, and the removal of impurities such as fluorite becomes the key to cassiterite flotation. In this study, the flotation separation of cassiterite (SnO 2) and fluorite (CaF 2) was enhanced by using hydroxylcitric acid (HCA) as fluorite inhibitor and 2-carboxyphenyl phosphonic acid (CEPPA) as collector. With a reagent scheme of 120 mg/L CEPPA and 4.5 mg/L HCA at pH 10.0, the flotation recovery of cassiterite and fluorite was 92.80% and 13.57%, respectively. Under the same experimental conditions of artificially mixed mineral flotation, the flotation index of cassiterite concentrate grade 78.19% and recovery 90.29% was obtained. The selective adsorption mechanism of CEPPA and HCA on minerals was investigated by Zeta potential, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The results showed that CEPPA anions had chemically adsorbed on cassiterite and fluorite, and the adsorption of HCA on fluorite surface was stronger than that on cassiterite surface. XPS analyses further confirmed that Ca sites exposed on fluorite had a stronger affinity for HCA than cassiterite. Furthermore, the addition of HCA had little effect on the adsorption of CEPPA on cassiterite, while the strong chemisorption of HCA on fluorite surface prevented the adsorption of CEPPA on fluorite. These results provide a theoretical basis and promising new strategy for the flotation separation of cassiterite and fluorite. [ABSTRACT FROM AUTHOR]

[Display omitted] • Diethylenetriaminepentaacetic acid (DTPA) strongly depresses the floatability of fluorite and not that of scheelite. • DTPA chemisorbs on the scheelite surface via the chelation of carboxyl groups and Ca species. • Strong adsorption of DTPA on the fluorite surface impedes the adsorption of NaOL. • The interaction between NaOL and scheelite is insignificantly influenced by the weak adsorption of DTPA. • DTPA can be used as an efficient depressant for the separation of scheelite from fluorite. The selective separation of scheelite from fluorite is difficult because of their similar surface properties. In this study, diethylenetriaminepentaacetic acid (DTPA) was used as a novel depressant for the efficient removal of fluorite from scheelite, and its depression effect and mechanism were systematically investigated by conducting micro-flotation experiments and a series of surface analyses. The micro-flotation experiments showed that the floatability of fluorite was significantly reduced by DTPA, whereas that of scheelite was minimally affected. Zeta potential measurements revealed that DTPA selectively adsorbed on fluorite surface and decreased the zeta potentials, whereas the zeta potentials of scheelite were negligibly influenced by DTPA. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy further proved that the interaction between DTPA and the fluorite surface was chemisorption, and in the adsorption configuration, the carboxyl groups of DTPA chelated with Ca sites on the fluorite surface. Additionally, an electrical analysis showed that electrostatic attraction facilitated the adsorption of DTPA on the fluorite surface. The adsorption of DTPA on fluorite surface could strongly inhibit the further adsorption of NaOL on fluorite surface, and therefore significantly depressed the floatability of fluorite. In contrast, the interaction between DTPA and scheelite was very weak and was impeded by steric hindrance caused by WO 4 2- and electrostatic repulsion. Therefore, DTPA has the potential to act as a depressant for the effective separation of scheelite from fluorite. [ABSTRACT FROM AUTHOR]

• An excellent separation performance of cassiterite from fluorite was achieved with PBTCA as a depressant. • PBTCA could be selectively chemisorbed on fluorite surface rather cassiterite surface. • The major interaction groups between PBTCA and fluorite were phosphate group and the calcium species, respectively. • The intensive adsorption of PBTCA on fluorite surface inhibited the further adsorption of NaOL. Cassiterite is the most purist tin-containing mineral and plays a dominative role in the tin resources. Owing to the limited selectivity of conventional collectors, the efficient separation of cassiterite from fluorite is normally difficult. Herein, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA) was employed as an eco-friendly depressant to selectively depress the flotation of fluorite. The flotation experiments were conducted to evaluate the separation efficiency of the two minerals, and the results showed that cassiterite and fluorite could be efficiently separated at the flotation reagent scheme of 15 mg/L PBTCA and 20 mg/L NaOL when pH was 8.04. Furthermore, a series of detection and simulation technologies including wettability analysis, zeta potential measurement, FTIR analysis, XPS analysis and DFT calculation were performed to uncover the underlying adsorption and depression mechanism of PBTCA on cassiterite and fluorite. These further analyses indicated that PBTCA could be chemisorbed on the fluorite surface through the interaction between the phosphate group in PBTCA and the calcium sites in fluorite. Moreover, the adsorption of PBTCA on fluorite surface would intensively inhibit the adsorption of NaOL. However, PBTCA was only weakly adsorbed on the cassiterite surface and could not affect the interaction between NaOL and cassiterite. Finally, a most likely adsorption model of PBTCA onto fluorite surface with the "mono-polar group" interaction was proposed by DFT calculations. [ABSTRACT FROM AUTHOR]

Owing to the similar surface properties of scheelite and fluorite, the separation of them is very difficult by only using the traditional collectors of fatty acids. In this study, Nitrilotri(methylphosphonic acid) (ATMP) was used as a depressant to realize the efficient separation of these two minerals. The separation performance and the adsorption mechanism of ATMP on scheelite and fluorite were explored by the flotation experiments and surface analyses. Flotation results indicated that ATMP exhibited strong inhibition on the fluorite flotation but did not affect that of scheelite, and a satisfactory separation of scheelite from fluorite was achieved at the reagent regime of 60 mg/L ATMP, 40 mg/L sodium oleate (NaOL) and pH 10.0. Zeta potential measurements and AFM detections showed that the intense adsorption of ATMP onto fluorite was occurred and which could prevent the subsequent adsorption of NaOL on fluorite, while the adsorption of ATMP onto scheelite was weak and the further interaction between NaOL and scheelite was hardly influenced by it. Moreover, Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analyses confirmed that the interaction between calcium ions exposed on fluorite surface and the phosphate groups of ATMP accounted for the chemisorption of ATMP on fluorite. As a result, ATMP can be selected as a potential depressant for separating scheelite from fluorite. [Display omitted] [ABSTRACT FROM AUTHOR]

• ATMP strongly depresses floatability of apatite more than that of scheelite. • Chemisorption of ATMP on apatite occurs between phosphate and calcium ions. • Significant adsorption of ATMP on apatite hinders adsorption of NaOL. • Adsorption of NaOL on scheelite was barely affected by weak adsorption of ATMP. • ATMP can be utilized as an efficient depressant for separating scheelite from apatite. The efficient separation of scheelite from apatite is still a big challenge by using froth flotation because of their similar surface's properties. In this study, the novel apatite depressant of nitrilotri(methylphosphonic acid) (ATMP) was first used to separate scheelite from apatite. The selective depression behavior and adsorption mechanism of ATMP on the two minerals were explored by a serie of experiments and surface analyses. The flotation experiments results showed that ATMP exhibited an intense inhibition effect on the flotation of apatite rather than scheelite. A satisfactory separation result with scheelite recovery of 85.22% and apatite recovery of 23.6% was achieved when ATMP was used as the depressant in the sodium oleate (NaOL) system. AFM detection and Zeta potential measurements indicated that ATMP could selectively adsorb onto apatite surface and intensively impede the further adsorption of NaOL, while the adsorption of NaOL onto scheelite surface was rarely affected by the pre-addition of ATMP. Moreover, FTIR and XPS analyses revealed that ATMP was chemisorbed onto apatite surface, and the interaction sites between ATMP and apatite were phosphate groups of ATMP and calcium species of apatite, respectively. Therefore, ATMP could be applied as a potential apatite depressant for effectively separating scheelite from apatite. [ABSTRACT FROM AUTHOR]

[Display omitted] • Apatite from dolomite was separated by new depressant flaxseed gum. • A concentrate with P 2 O 5 recovery of 76.43% and P 2 O 5 grade of 39.39% was obtained. • Flaxseed gum could not be adsorbed on apatite surface at pH 8. • Flaxseed gum was chemisorbed on dolomite surface by the sites of Ca and Mg. Apatite was firstly separated from dolomite by utilizing flaxseed gum as depressant and NaOL as collector. Single mineral and apatite-dolomite binary mixed ore flotation experiments were performed. The results revealed that under the conditions of pH 8, flaxseed gum 40 mg/L and NaOL 40 mg/L, single apatite and dolomite recovery was 78.47% and 1.98% respectively. For the apatite-dolomite binary mixed ore flotation experiments, the P 2 O 5 recovery and P 2 O 5 grade of the concentrate was 76.43% and 39.39% respectively. Flaxseed gum could selectively depress dolomite flotation and achieve the separation of apatite from dolomite. Atomic force microscope (AFM), zeta potential measurements, Fourier transformed infrared (FT-IR), and X-ray photoelectron spectroscopy (XPS) were carried out to reveal the mechanism. The results revealed that flaxseed gum could not be adsorbed on apatite at pH 8, while it was chemisorbed on dolomite by the sites of Ca and Mg. Therefore, the NaOL could still be adsorbed on apatite at pH 8 and flaxseed gum could not impede it, but the further adsorption of NaOL on dolomite was hindered by flaxseed gum. Thus, flaxseed gum selectively depressed the flotation of dolomite and realized the separation of apatite from dolomite. [ABSTRACT FROM AUTHOR]

• Effect of particle size on molybdenite flotation was investigated. • NBs were introduced to enhance the recovery of ultrafine molybdenite. • The recovery of ultrafine molybdenite increased approximately 15.17% by NBs. • NBs reduced the repulsive force among particles and facilitated their aggregation. It is well known that fine and ultrafine particles are difficult to recover through froth flotation because of low bubble–particle collision efficiencies. In this study, we first explored the influence of particle size on the flotation behavior of molybdenite. To address the problem of low recovery of ultrafine molybdenite, nanobubbles (NBs) were introduced to promote the flotation efficiency, and the enhanced effect was investigated by micro-flotation experiments. The results of the flotation experiments showed that as the particle size decreased, the recovery of molybdenite decreased dramatically, especially for particles smaller than 23 μm. The introduction of NBs can significantly facilitate ultrafine molybdenite recovery. Moreover, the strengthening mechanism was uncovered through zeta potential measurements, turbidity tests, microscopic imaging, and wettability analysis. The analyzed results illustrated that the attachment of NBs to ultrafine molybdenite reduced the repulsive force between particles, facilitating particle aggregation and enhancing the hydrophobicity of the mineral surface, which further enhanced the bubble–particle collision and attachment, thereby improving the flotation recovery. [ABSTRACT FROM AUTHOR]

• HCA could selectively separate cassiterite from calcite with SPA as a collector. • The recovery of cassiterite and calcite was 82.01% and 19.18% respectively. • A tin concentrate with Sn grade of 62.24% and recovery of 85.60% was obtained. • HCA was adsorbed on calcite through chemisorption. • Ca atom on calcite surface was the active site to react with HCA. In this study, the flotation separation of cassiterite (SnO 2) from calcite (CaCO 3) was investigated using hydroxycitric acid (HCA) which could effectively depress the flotation of calcite. Under the conditions of pH 8.0, styrene phosphonic acid (SPA) 80 mg/L, and HCA 6 mg/L, the flotation recovery of cassiterite and calcite was 82.01% and 19.18%, respectively, in the flotation experiments of single mineral, and a cassiterite concentrate with Sn grade of 62.24% and recovery of 85.60% was obtained in the flotation experiments of mixed artificial binary ore. The mechanism was also investigated by zeta potential measurements, Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) analyses. The results illustrated that HCA selectively adsorbed on the calcite surface and could hinder the adsorption of SPA on calcite surfaces. However, SPA could still adsorb on cassiterite surface in the presence of HCA. Moreover, the results of FT-IR and zeta potential measurement indicated that there was specific adsorption between HCA and calcite, and XPS results revealed that HCA was adsorbed on the calcite surface through the interaction between the carboxyl groups of HCA and the Ca atom on the calcite surface. HCA could be used as a potential depressant in the flotation separation of cassiterite from calcite. [ABSTRACT FROM AUTHOR]

Cu2+ was found to have intensive and selective depressing effects on fluorite in the flotation separation of cassiterite from fluorite using 2-carboxyethylphenylphosphinic acid (CEPPA) as a collector at pH 4.0. The depressing mechanism was investigated by flotation tests, zeta potential measurements, X-ray photoelectron spectroscopy (XPS) analyses and density functional theory (DFT) calculations. Flotation test results demonstrated that Cu2+ selectively depressed the fluorite in an artificially mixed cassiterite-fluorite ore. Zeta potential measurement and XPS analysis results indicated that Cu2+ could be anchored on cassiterite surface by adsorption or substitution but not on fluorite surface, and the adsorption of CEPPA on fluorite surface was cut off by Cu2+. DFT calculation results demonstrated that CEPPA had stronger affinity for Cu2+ than for fluorite, and the adsorption or substitution of Cu2+ on cassiterite (110) surface showed no negative effects on the adsorption of CEPPA monoanion on cassiterite (110) surface. Based on these results, the depressing mechanism of Cu2+ on fluorite was that Cu2+ consumed the collector CEPPA in solution, and little free CEPPA was left to be adsorbed on fluorite surface while the adsorption of CEPPA on cassiterite was normal. Thus, the floatation of fluorite was selectively and intensively weakened. Unlabelled Image • The separation of cassiterite from fluorite was successfully achieved using a novel collector and depressant combination. • Cu2+ was proved to be an effective and selective depressant for fluorite. • CEPPA had stronger affinity for Cu2+ than for fluorite surface in solution. • Cu2+ could be anchored on cassiterite surface by substitution or adsorption. • Cu2+ consumed the collector CEPPA in solution and little free collector was left to be adsorbed on fluorite surface. [ABSTRACT FROM AUTHOR]

Froth flotation has become the dominant technique for separating cassiterite and fluorite. However, due to the limited selectivity of conventional collectors, fluorite was always collected with cassiterite simultaneously in the absence of depressants, which could reduce the grade of concentrate and economic benefits. In this paper, galactomannan (GM) was used as a selective depressant to facilitate the separation of cassiterite and fluorite, and the separation effect was evaluated by the flotation experiments. The results showed that the flotation of cassiterite was significantly depressed while that of fluorite was nearly affected. Moreover, the adsorption mechanism of GM onto the two minerals was investigated by zeta potential measurements, Fourier transform infrared spectroscopy (FT-IR), atomic force microscope (AFM), and X-ray photoelectron spectroscopy (XPS) analyses. It was found that GM was adsorbed on cassiterite through chemisorption and the main active sites of cassiterite to react with GM were Sn. Meanwhile, the adsorption density of GM onto cassiterite was much more than that onto fluorite, which also further caused SPA could not be adsorbed onto the surface of cassiterite in the presence of GM. Therefore, GM could be utilized as a potential depressant for separation cassiterite and fluorite. Unlabelled Image • Galactomannan (GM) could select as an efficient depressant for the separation of cassiterite and fluorite. • The adsorption density of GM onto cassiterite was much more than that onto fluorite. • GM could impede the adsorption of SPA on cassiterite • GM was adsorbed on cassiterite by chemisorption and the main active sites of cassiterite to react with GM were Sn. [ABSTRACT FROM AUTHOR]