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Separation of scheelite from calcite by froth flotation using a new amidoxime surfactant - 3-dodecylamine propyl amidoxime (DPA). [Display omitted] • A new amidoxime surfactant DPA was used to flotation separate scheelite and calcite. • Scheelite and calcite recovery were 92% and 4.5% respectively. • DPA exhibited preferable selectivity than NaOL in the absence of depressant. • The interaction of DPA surfactant on scheelite surface is electrostatic adsorption. With its high electrical conductivity, thermal creep resistance and compression modulus, tungsten take an irreplaceable position in modern industry, defense, and high technology. Scheelite, as the main raw material of tungsten resources, usually adopts Petrov' process: steam heating 80 °C-90 °C, stirring in a tank containing 2%-4% sodium silicate solution for more than half an hour to make sodium oleate desorbed on the calcite surface, and repeated cleaning. Herein, a new amidoxime surfactant 3-dodecylamine propyl amidoxime (DPA), had been synthesized and used as a collector for the first time in the flotation separation of scheelite and calcite at room temperature without any sodium silicate, and compared with the traditional collector sodium oleate (NaOL). The flotation behavior of DPA was studied by micro-flotation and mixed binary mineral flotation tests, which showed that DPA has good collection ability and excellent selectivity for scheelite. Meanwhile, the interaction mechanism of DPA on the mineral surface was discussed by FTIR analysis, zeta potential test, contact angle measurement and density functional theory (DFT). FTIR analysis and zeta potential test confirmed that DPA collector had adsorption on scheelite surface but had little effect on calcite. DFT calculation further confirmed that the positively charged –C(NOH)N+H 3 group in DPA had electrostatic adsorption on the negatively charged scheelite surface. The contact angle measurement results revealed that DPA can enhance the surface hydrophobicity of the scheelite particles. Therefore, this highly selective DPA surfactant can achieve effective separation of scheelite and calcite, contributing to environmental protection and sustainable green development of resources. [ABSTRACT FROM AUTHOR]

Wolframite was separated and extracted from calcite by using a new type of amidoxime surfactant − 3-dodecylamine propyl amidoxime (DPA) as a flotation collector. [Display omitted] • A novel amidoxime surfactant DPA was synthesized by lab. • DPA was first introduced in flotation for separation of wolframite from calcite. • DPA has superior selective adsorption performance at wolframite interface. • The wolframite recovery was 96% and calcite only 2 % at pH 7 and 2 × 10-4mol/L DPA. This study concentrated on the adsorption features and mechanism of a novel amidoxime surfactant 3-dodecylamine propyl amidoxime (DPA) used as a new wolframite collector on wolframite and calcite surfaces. The flotation experiment showed that DPA collector has a remarkable flotation separation effect on wolframite and calcite. Additionally, the results of the contact angle and zeta potential measurements, and FTIR spectral analysis revealed that the DPA had produced strong electrostatic adsorption on the surface of wolframite, but almost no adsorption on calcite. The results of the DFT calculation showed that DPA had a strong effect on the wolframite surface mainly through the positive charged –C(NOH)N+H 3 group. It provides a new idea for the flotation separation of wolframite and calcite. [ABSTRACT FROM AUTHOR]

In this paper, a Gemini surfactant, ethane-1,2-bis(dimethyl-dodecyl-ammonium bromide) (EBAB), was introduced as a collector for reverse cationic flotation separation of quartz from magnetite, and its adsorption mechanisms on the two minerals and air/water interface were also investigated by FTIR spectra, zeta potential, density functional theory (DFT) calculation and surface tension. The flotation results showed that EBAB presented stronger collecting power than the conventional monomeric surfactant dodecylammonium chloride (DAC) and superior selectivity for quartz against magnetite. The results of FTIR spectra and zeta potential measurements demonstrated that the interaction of EBAB with quartz and magnetite was mainly through electrostatic attraction, which was further confirmed by DFT calculation. EBAB was preferred to adsorb on the negatively charged surface of quartz, increasing its zeta potentials and improving its hydrophobicity. Adsorption of EBAB at the quartz/water interface could be divided into four stages as the concentration of EBAB was increased in solution. At low concentrations, adsorption was controlled primarily by electrostatic interactions, but when the zeta potential of quartz was reversed from negative to positive, hydrophobic chain interactions controlled the adsorption process. EBAB’s unique properties, such as high positive grouping Mulliken charge of –CH 2 N + (CH 3 ) 2 (CH 2 ) 2 (CH 3 ) 2 N + CH 2 –, and strong “surface activity” at the air–water interface, made it be a superior cationic collector for reverse flotation desilication from iron ores. [ABSTRACT FROM AUTHOR]

How to flotation fine kaolinite efficiently is a challenge. For the improvement of fine kaolinite flotation recovery, a novel 3-tetradecylamine propyl amidoxime (TPA) collector was synthesized. In comparison to the conventional collector tetradecylamine (TDA), the fine kaolinite exhibited better floatability in the TPA system, with a recovery of 90.5% in micro-flotation experiments. It was indicated by contact angle tests that TPA was more effective in improving the hydrophobicity of kaolinite by increasing its contact angle from 24.5° to 85°. Fourier transform infrared spectroscopy (FTIR) indicated that the adsorption of TPA on kaolinite surface was by electrostatic interaction, and zeta potential tests showed a significant increase in the surface potential. In addition, it was learned that TPA interacts with the kaolinite surface more effectively than TDA by using density functional theory (DFT) calculation. Therefore, TPA with excellent performance is expected to be a novel and efficient fine kaolinite flotation collector. [Display omitted] • Conventional collectors are difficult to flotation fine kaolinite efficiently. • Novel TPA collector exhibited excellent flotation performance for fine kaolinite. • Adsorption mechanism of TPA molecules at kaolinite surfaces was investigated. [ABSTRACT FROM AUTHOR]

The diagrammatic sketch of flotation separation of calcite and quartz from malachite ore by using DHH/OHA. [Display omitted] • N1,N10 -dihydroxydecanediamide (DHH) was introduced in malachite flotation firstly. • Calcite and quartz were separated by flotation using DHH collector. • DHH exhibited an excellent collecting ability to malachite. In this study, a novel collector, N1,N10 -dihydroxydecanediamide (DHH) was synthesized in our lab and introduced in flotation of malachite ore. The separation performance and action mechanism of DHH were explored and compared with octyl hydroxamic acid (OHA). The results of single mineral flotation tests indicated that DHH exhibited a stronger collecting ability to malachite and better selectivity against quartz and calcite than OHA, and floated out 94 % malachite, 8.5 % quartz and 17 % calcite at pH = 10 with a collector concentration of 60 mg/L. The FTIR spectra, zeta-potential tests and XPS tests proved that DHH could absorb onto malachite surface though a chemical mode. DFT calculation results showed that DHH anion owned a stronger affinity to malachite than DHH molecular and OHA anion/molecular, and its bis-minerophilic groups could form C(=O)NHO-Cu bond with surface Cu atom. It exhibited that DHH was an excellent candidate and capable for high efficiency flotation of malachite ore. [ABSTRACT FROM AUTHOR]

Acid mine drainage (AMD) is an acidic effluent containing many toxic heavy metal ions (e.g. Cu2+, Cd2+, Hg2+) in mining industry, leading to serious environmental issues such as natural soil and aquatic pollution that threats the whole ecosystem and biosafety. Conventional neutralization and precipitation process cannot effectively remove heavy metal ions due to the risk of secondary contamination. Herein, we report an engineered amorphous molybdenum sulphide composite for selective removal of heavy metal ions from other co-existing ions in AMD solution. This composite was prepared by a facile ion exchange reaction, in which tetrathiomolybdate (MoS 4 2-) anions are firmly bonded to strong anion exchange resins by replacing chloride ions. The obtained composite was used to remove heavy metal ions from both synthetic and authentic AMD solution. The results of batch and fixed-bed column tests suggest high selectivity towards heavy metals, fast adsorption kinetics, good reusability and excellent adsorption capacities in the order of Hg(II)>>Pb(II)>Cu(II)>Cd(II). The adsorption data are fitted well by Langmuir model, indicating the single-layer adsorption mechanism. The theoretical adsorption capacities calculated by Langmuir model are 259.0 mg/g for Cu(II), 204.1 mg/g for Cd(II), 495.0 mg/g for Pb(II) and 1538.4 mg/g for Hg(II). The interaction between metal ions (Cu, Cd, Pb, Hg) and MoS 4 2- anions are demonstrated by the formation of Mo-S-metal (Cu, Cd, Pb, Hg) bonding (the red shift of S2p peak in XPS spectra). Our results support the potential practical application of this new material for scavenging heavy metal ions in AMD wastewater. [ABSTRACT FROM AUTHOR]

Graphical abstract Absorption model of tert -butylsalicylaldoxime (TBSA) on the surface of malachite. Highlights • Tert -butylsalicylaldoxime (TBSA) was introduced in malachite flotation. • TBSA exhibited superior selectivity for malachite against calcite or silica. • TBSA adsorbed on malachite surfaces though N O Cu and d-pπ bond. Abstract In this research, the flotation performance and adsorption mechanism of tert -butylsalicylaldoxime (TBSA) to malachite were studied by micro-flotation, contact angle, zeta potential, FTIR and XPS analysis. The result of micro-flotation tests indicated TBSA yielded high malachite recovery and satisfied selectivity against calcite or silica at pH 9.0–10.5. The contact angle results inferred that the hydrophobicity of malachite surfaces was improved after TBSA modification. The results of zeta potential suggested that TBSA might chemisorb on malachite surfaces. XPS and IR spectrum analysis confirmed that the O atoms in C N OH group and benzene ring fixed with Cu species on malachite surfaces through C O Cu, N O Cu and d-pπ bond respectively. [ABSTRACT FROM AUTHOR]