Flotation Behavior of Different Colored Fluorites Using Sodium Oleate as a Collector

Using sodium oleate (NaOL) as a collector, the flotation characteristics of natural colorless fluorite (CF), green fluorite (GF), and purple fluorite (PF) were investigated through micro-flotation tests, collector adsorption measurements, and surface tension measurement. The micro-flotation results indicated that CF had a much better flotation response than both GF and PF, and had higher floatation recovery. The results demonstrated a considerable discrepancy in the interfacial properties between colorless and colored fluorite, even though all the samples were obtained from the same deposit, holding a similar high purity of CaF2. The adsorption capacity of CF, GF, and PF for NaOL was 2.27, 4.18, and 8.21 × 10−6 mol/g under neutral conditions, respectively. Fourier transform infrared (FT-IR) measurements revealed that the carboxyl groups of NaOL reacted with Ca sites on the surface of fluorites by chemical adsorption. From the zeta potential analyses, PF exhibited a lower positive potential than CF and GF, mainly due to its surface carbonation. In the presence of NaOL, the surface potential of fluorites changed from positive to negative because the NaOL collector had been adsorbed onto the mineral surface and changed their surface potential, which was consistent with the flotation results at different pH values. We found that the floatability of the fluorite samples was influenced by their surface roughness, measured by an atomic force microscope (AFM) and scanning electron microscope (SEM). PF can be floated with adding more reagent dosage than CF and GF to compensate for its higher surface roughness

Flotation Behavior of Different Colored Fluorites Using Sodium Oleate as a Collector

Using sodium oleate (NaOL) as a collector, the flotation characteristics of natural colorless fluorite (CF), green fluorite (GF), and purple fluorite (PF) were investigated through micro-flotation tests, collector adsorption measurements, and surface tension measurement. The micro-flotation results indicated that CF had a much better flotation response than both GF and PF, and had higher floatation recovery. The results demonstrated a considerable discrepancy in the interfacial properties between colorless and colored fluorite, even though all the samples were obtained from the same deposit, holding a similar high purity of CaF2. The adsorption capacity of CF, GF, and PF for NaOL was 2.27, 4.18, and 8.21 × 10−6 mol/g under neutral conditions, respectively. Fourier transform infrared (FT-IR) measurements revealed that the carboxyl groups of NaOL reacted with Ca sites on the surface of fluorites by chemical adsorption. From the zeta potential analyses, PF exhibited a lower positive potential than CF and GF, mainly due to its surface carbonation. In the presence of NaOL, the surface potential of fluorites changed from positive to negative because the NaOL collector had been adsorbed onto the mineral surface and changed their surface potential, which was consistent with the flotation results at different pH values. We found that the floatability of the fluorite samples was influenced by their surface roughness, measured by an atomic force microscope (AFM) and scanning electron microscope (SEM). PF can be floated with adding more reagent dosage than CF and GF to compensate for its higher surface roughness

Evaluation of Sulfonate-Based Collectors with Different Hydrophobic Tails for Flotation of Fluorite

This investigation aims to demonstrate the effects of hydrophobic tails on the affinity and relevant flotation response of sulfonate-based collectors for fluorite. For this purpose, a series of alkyl sulfonates with different hydrophobic tails, namely sodium decanesulfonate (C10), sodium dodecylsulfate (C12), sodium hexadecanesulfonate (C16), and sodium dodecylbenzenesulfonate (C12B) were applied. The flotation tests showed that C12 and C12B had a better collecting performance than C10 and C16 at pH < 10, and the flotation recovery of fluorite was higher when adopting C12B as a collector compared with C12 with a strong base. The adsorption behaviors of collectors on the fluorite surface were studied through zeta potential, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) analyses. It was found that the affinity of alkyl sulfonates for fluorite was enhanced with the increase of the alkyl chain length from C10 to C16. The existence of phenyl in the hydrophobic tail of sulfonates could improve its activity for fluorite by reducing its surface tension. The abnormal phenomenon C16 with a high affinity for fluorite had a low collecting performance for fluorite mainly due to its overlong alkyl chain, resulting in low solubility in pulp, which restrained its interaction with fluorite. We concluded that C12B was the most applicable collector for fluorite among these reagents due to its high activity, high solubility, and low cost, which was further substantiated by calculating their molecular frontier orbital energy

Sodium N-Lauroylsarcosinate (SNLS) as a Selective Collector for Calcareous Phosphate Beneficiation

Sodium N-lauroylsarcosinate (SNLS) was employed as a selective flotation collector for dolomite–apatite separation. The influence of pH, condition time, and collector dose on the flotation performance of both apatite and dolomite minerals was investigated using single mineral and binary mixed mineral flotation experiments. The performance of SNLS was compared to sodium oleate (NaOL), as a standard collector. In this study, the adsorption mechanism of SNLS on both minerals was studied using zeta-potential and FT-IR measurements. The results showed that SNLS prefers to adsorb on the dolomite mineral. The maximum difference in floatability was 83% for single dolomite and apatite minerals at pH 10 in the presence of 0.05 mmol/L SNLS. Binary mixtures of dolomite and apatite minerals of different ratios were applied, to evaluate their separation efficiency. The SNLS could separate dolomite from its mixtures with apatite minerals. Using 0.2 mmol/L of SNLS at pH 10, a concentrate of 30.9% P2O5 and 0.79% MgO was obtained from a natural phosphate ore having 25.8% P2O5 and 5.16% MgO

Kinetics of Rare Earth and Aluminum Leaching from Kaolin

In this paper, magnesium sulfate was used as a lixiviant to recover rare earth from kaolin. The effects of column leaching conditions, such as the concentration of magnesium sulfate, liquid/solid ratio, flow rate, and pH of the magnesium sulfate solution on the leaching efficiency of rare earth and aluminum, were investigated. In addition, the leaching kinetics of rare earth and aluminum were analyzed based on the magnesium concentration. The results showed that the optimal leaching conditions 0.2 mol/L magnesium sulfate solution with no pH adjustment, 1.2:1 for the liquid/solid ratio, and at a flow rate of 0.5 mL/min led to an 89% rare earth leaching efficiency and an 81% aluminum leaching efficiency. The aluminum leaching efficiency by magnesium sulfate was 7% less than that by ammonium sulfate. Moreover, the equilibrium time for rare earth was 33 min shorter than aluminum, which is of benefit to reduce the leaching time of aluminum. The leaching kinetic data fitted an unreacted shrinking-core model. Semi-empirical equations based on the apparent rate constant and magnesium concentration of rare earth and aluminum were established, and the reaction orders for rare earth and aluminum were determined to be 1.69 and 1.61, respectively. The results of this study could help to better understand and optimize the leaching process by magnesium sulfate

Ethylenediamine tetramethylenephosphonic acid as a selective collector for the improved separation of chalcopyrite against pyrite at low alkalinity

Chalcopyrite is the main Cu-containing mineral and cannot be separated well from pyrite using traditional xanthate collectors with large amounts of lime depressant, resulting in difficulties of the tailing treatment and associated precious metals recovery. Therefore, in this study, the green and odourless ethylenediamine tetramethylenephosphonic acid (EDTMPA) was introduced as a novel chalcopyrite collector. Flotation results from the binary mineral mixture and real ore demonstrated that EDTMPA could realize the selective separation of chalcopyrite from pyrite relative to ethyl xanthate (EX) without any depressants within the wide pH range of 6.0–11.0, and might replace the traditional high-alkaline lime process. Electrochemical and Fourier transform infrared spectra measurements indicated that the difference in adsorption performance of EDTMPA on chalcopyrite and pyrite was larger than that of EX, suggesting a better selectivity for EDTMPA. Density functional theory calculations demonstrated that there were stronger chemical bonds between P—O groups of EDTMPA and the Fe/Cu atoms on chalcopyrite in the form of a stable six-membered ring. Crystal chemistry calculations further revealed that the activity of metal atoms of chalcopyrite was higher than that of pyrite. Therefore, these basic theoretical results and practical application provide a guidance for the industrial application of EDTMPA in chalcopyrite flotation

Sodium N-Lauroylsarcosinate (SNLS) as a Selective Collector for Calcareous Phosphate Beneficiation

Sodium N-lauroylsarcosinate (SNLS) was employed as a selective flotation collector for dolomite–apatite separation. The influence of pH, condition time, and collector dose on the flotation performance of both apatite and dolomite minerals was investigated using single mineral and binary mixed mineral flotation experiments. The performance of SNLS was compared to sodium oleate (NaOL), as a standard collector. In this study, the adsorption mechanism of SNLS on both minerals was studied using zeta-potential and FT-IR measurements. The results showed that SNLS prefers to adsorb on the dolomite mineral. The maximum difference in floatability was 83% for single dolomite and apatite minerals at pH 10 in the presence of 0.05 mmol/L SNLS. Binary mixtures of dolomite and apatite minerals of different ratios were applied, to evaluate their separation efficiency. The SNLS could separate dolomite from its mixtures with apatite minerals. Using 0.2 mmol/L of SNLS at pH 10, a concentrate of 30.9% P2O5 and 0.79% MgO was obtained from a natural phosphate ore having 25.8% P2O5 and 5.16% MgO

Design of earth‐abundant amorphous transition metal‐based catalysts for electrooxidation of small molecules: Advances and perspectives

Abstract Electrochemical oxidation of small molecules (e.g., water, urea, methanol, hydrazine, and glycerol) has gained growing scientific interest in the fields of electrochemical energy conversion/storage and environmental remediation. Designing cost‐effective catalysts for the electrooxidation of small molecules (ESM) is thus crucial for improving reaction efficiency. Recently, earth‐abundant amorphous transition metal (TM)‐based nanomaterials have aroused souring interest owing to their earth‐abundance, flexible structures, and excellent electrochemical activities. Hundreds of amorphous TM‐based nanomaterials have been designed and used as promising ESM catalysts. Herein, recent advances in the design of amorphous TM‐based ESM catalysts are comprehensively reviewed. The features (e.g., large specific surface area, flexible electronic structure, and facile structure reconstruction) of amorphous TM‐based ESM catalysts are first analyzed. Afterward, the design of various TM‐based catalysts with advanced strategies (e.g., nanostructure design, component regulation, heteroatom doping, and heterostructure construction) is fully scrutinized, and the catalysts’ structure‐performance correlation is emphasized. Future perspectives in the development of cost‐effective amorphous TM‐based catalysts are then outlined. This review is expected to provide practical strategies for the design of next‐generation amorphous electrocatalysts

and GIS technologies

ABSTRACT. Glacier and lake variations in the Yamzhog Yumco basin in southern Tibet were studied by integrating series of spatial data from topographic maps and Landsat images at three different times: 1980, 1988/90 and 2000. The results indicate that the total glacier area has decreased fro

Dual-Doped Nickel Sulfide for Electro-Upgrading Polyethylene Terephthalate into Valuable Chemicals and Hydrogen Fuel

Highlights Co and Cl co-doped NiS is an efficient bifunctional electrocatalyst for converting plastic waste into formate and hydrogen with high efficiency and selectivity Dopants regulate the electronic property and accelerate structural reconstruction of NiS for the core ethylene glycol (PET monomer) oxidation reaction PET hydrolysate electrolysis can produce hydrogen gas at an average rate of 50.26 mmol h−1 at 1.7