Role of ammonium sulfate in sulfurization flotation of azurite: Inhibiting the formation of copper sulfide colloid and its mechanismOA

In this study, the role of(NH₄)₂SO₄ during the sulfurization of azurite and its response to flotation were investigated. The flotation results showed that adding(NH₄)₂SO₄ prior to sulfurization decreased the formation of colloid in flotation pulp, and the floatability of the suppressed azurite caused by excess sodium sulfide was restored. After adding(NH₄)₂SO₄ prior to sulfurization, the formation ...     

碳源对反硝化脱硫工艺碳氮硫同步脱除效果的影响

针对碳源对反硝化脱硫工艺运行效能影响不明问题,实验采用UASB反应器,考查两种不同碳源(乙酸钠和苯酚)条件下反硝化脱硫工艺碳氮硫去除效果及单质硫累积率,在此基础上,通过批次试验进一步探究碳氮硫降解及转化规律.结果表明:乙酸钠为碳源,HRT为2.5~10 h,NO_3~--N、S~(2-)和Ac~--C去除率分别保持在93%、90%和99%以上,单质硫积累率稳定在41%以上;而苯酚为碳源,HRT为10 h,NO_3~--N、S~(2-)和C_6H_5O~--C去除率分别达67%、85%和50%,但硫化物均转化为硫酸盐,无单质硫累积.批次试验表明,乙酸钠为碳源时,S~(2-)氧化速率(qS~(2-))乙酸盐氧化速率(qAcetate)S~0的氧化速率(q_S~0);而苯酚为碳源时,S~(2-)氧化速率(qS~(2-))S0的氧化速率(q_S~0)苯酚氧化速率(qPhenol),从而使得硫化物的氧化产物有所差异.     

Flotation of copper oxide minerals: A reviewOA

Copper oxide minerals are important copper resources, which include malachite, azurite, chrysocolla,cuprite, etc. Flotation is the most widely used method for the enrichment of copper oxide minerals in the mineral processing industry. In this paper, the surface properties of copper oxide minerals and their effects on the mineral flotation behavior are systematically summarized. The flotation methods of copper oxide minerals and the interaction mechanism with reagents are reviewed in detail. Flot...     

Model of diffusion of sulfur in soda-lime-silicate glass: An experimental and comparative study

The diffusion property of sulfur on the soda-lime-silicate float glass surface was studied by using secondary ion mass spectroscopy(SIMS). According to the Fick`s Second Law, two models of diffusion of sulfur on the glass surface were built. When the diffusion of sulfate (S⁶⁺) is considered uniquely, the concentration-depth profile of sulfur can not be fitted very well, especially on the top surfaces of the air side and tin side of float glass. So the diffusion of sulfide (S^2-) on the profile of sulfur can not be ignored. The concentration-depth profile of sulfur on both sides of glass can be fitted more exactly when both S⁶⁺ and S^2- are considerd. Based on the above-mentioned fitting results, it is concluded that the diffusion coefficents of S⁶⁺ and S^2- of tin side are larger than those of the air side. Moreover, the diffusion coefficents are related to the contacted medium.     

HYDROPHOBICITY－HYDROPHILICITY BALANCE RELATIONSHIPSFORCOLLECTORLESSFLOTATIONOFSULPHIDEMINERALS

ＨＹＤＲＯＰＨＯＢＩＣＩＴＹ－ＨＹＤＲＯＰＨＩＬＩＣＩＴＹＢＡＬＡＮＣＥＲＥＬＡＴＩＯＮＳＨＩＰＳＦＯＲＣＯＬＬＥＣＴＯＲＬＥＳＳＦＬＯＴＡＴＩＯＮＯＦＳＵＬＰＨＩＤＥＭＩＮＥＲＡＬＳＨＹＤＲＯＰＨＯＢＩＣＩＴＹ－ＨＹＤＲＯＰＨＩＬＩＣＩＴＹＢＡＬＡ...     

Stabilization of lanthanum sulfides with different dopants

By introducing different dopants into the lattice, lanthanum sulfides with higher stability were prepared via the sulfurization of lanthanum oxides using CS2 gas at 1 000 ℃. The sulfurizing time of 8 hours was optimized for La/Ca=2 at 1 000 ℃ and its sulfurization mechanism to form CaLa2S4 was via the reaction of β-La2S3 with CaS. As the increase of the La/Ca and La/Na ratio, longer sulfurizing time was required to get cubic phase. The investigation indicates that Na+ ions were more effective to stabilize cubic structure comparing with Ca2+ ions.     

Effect of deep oxidation of chalcopyrite on surface properties and flotation performanceOA

In this study, chalcopyrite was oxidized in hydrogen peroxide(H₂O₂) solutions of different concentrations to simulate different degrees of oxidation in real ores, and the effects of H₂O₂ treatment on chalcopyrite surface properties and flotation performance were investigated by surface analysis techniques and floatation experiments, which implied the reason for the poor grade and recovery of oxidized chalcopyrite concentrate in the production process o...     

Scintillation properties of Gd doped β-PbF2 crystal

A single crystal sample of cubic lead fluoride doped with gadolinium (β-PbF₂:Gd) was prepared by use of the Bridgman-Stockbarger method. The crystal samples for testing with dimension of ø20 mm×20mm long were all polished. The dopant level of gadolinium is 0.15wt%. The light output and decay time of the samples were measured in the lab using¹³⁷Cs source and 1 GeV test beam at AGS respectively. Experimental results indicated that β-PbF₂:Gd crystal produces a weak scintillation emission at room temperature corresponding to a light output of ～6 photoelectrons per MeV and most of the light is collected within a gate of 30 ns. There is no evidence of any significant slow component extending out of 1 μs. In the X-ray excited emission spectra of β-PbF₂:Gd at room temperature, two emission peaks, 277 nm and 312 nm, were found and corresponded to the transition of⁶I_J→⁸S_7/2 and⁶P_J→⁸S_7/2 of Gd³⁺ ions, respectively.     

A direct atomic layer deposition method for growth of ultra-thin lubricant tungsten disulfide films

We describe a direct atomic layer deposition method to grow lubricant tungsten disulfide (WS₂) films. The WS₂ films were deposited on a Si (100) substrate and a zinc sulfide (ZnS) film coated the Si (100) substrate using tungsten hexacarbonyl and hydrogen sulfide as precursors. The ZnS film served as an intermediate layer to facilitate the nucleation and growth of the WS₂ films. The thickness of the WS₂ films was measured via scanning electron microscope, the microstructure was probed with an X-ray diffractometer and a transmission electron microscope. The friction coefficient was measured with a ball-on-disk tester under dry nitrogen. The results reveal that the WS₂ films deposited on both substrates are ~175 nm and have (002) and (101) crystal orientations. The WS₂ film deposited on the ZnS coated Si substrate exhibits a stronger (002) orientation and a denser crystal structure than that deposited on the Si substrate. The WS₂ films on both substrates have low friction coefficients. However, due to the stronger (002) orientation and denser crystal structure, the friction coefficient of the WS₂ film deposited on ZnS coated Si substrate is smaller with longer wear life.     

硫化镍及硫化铜镍矿石选矿概述

概括地介绍了硫化镍及硫化铜镍矿的矿物特性、浮选性质及其选矿的工艺特点,并指出了对硫化铜镍矿的综合利用及选矿任务。     

Influence of surface roughness on flotation kinetics of quartz

Surface roughness of quartz particles was determined by measuring the specific surface area of particles. The wettability characteristics of particles were determined by measuring the flotation rate using a laboratory flotation cell. Experimental results show that the rod mill product has higher roughness than the ball mill product. For the particles with larger surface roughness, the flotation kinetics constant is also higher. Finally, empirical relationships between surface roughness (r) and the flotation kinetics constant (k) of quartz particles as k=A+Br+Cr ^0.5lnr+D/lnr+E/r and k=A+Br are presented, in which A, B, C, D and E are constants related to experimental conditions and mineralogical properties of mineral.     

CFD model simulation of bubble surface area flux in flotation column reactor in presence of minerals

Bubble surface area flux(S_b) is one of the main design parameter in flotation column that typically employed to describe the gas dispersion properties, and it has a strong correlation with the flotation rate constant. There is a limited information available in the literature regarding the effect of particle type,density, wettability and concentration on Sb. In this paper, computational fluid dynamics(CFD) simulations are performed to study the gas–liquid–solid three-phase flow dynamics in flotation column by employing the Eulerian–Eulerian formulation with k-e turbulence model. The model is developed by writing Fortran subroutine and incorporating then into the commercial CFD code AVL FIRE, v.2014.This paper studies the effects of superficial gas velocities and particle type, density, wettability and concentration on Sband bubble concentration in the flotation column. The model has been validated against published experimental data. It was found that the CFD model was able to predict, where the response variable as indicated by R-Square value of 0.98. These results suggest that the developed CFD model is reasonable to describe the flotation column reactor. From the CFD results, it is also found that Sb decreased with increasing solid concentration and hydrophobicity, but increased with increasing superficial gas velocity. For example, approximately 28% reduction in the surface area flux is observed when coal concentration is increased from 0 to 10%, by volume. While for the same solid concentration and gas flow rate, the bubble surface area flux is approximately increased by 7% in the presences of sphalerite.A possible explanation for this might be that increasing solid concentration and hydrophobicity promotes the bubble coalescence rate leading to the increase in bubble size. Also, it was found that the bubble concentration would decrease with addition of hydrophobic particle(i.e., coal). For instance, under the same operating conditions, approximately 23% reduction in the bubble concentration is predicted when the system was working with hydrophobic particles. The results presented are useful for understanding flow dynamics of three-phase system and provide a basis for further development of CFD model for flotation column.     

Synthesis and coloring properties of Cd（S1-xSex） pigments by precipitate-hydrothermal method

Cd（S1-xSex） pigments （red to yellow） were synthesized by precipitate-hydrothermal method. The structure, morphology and hue of the powder were characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, energy dispersive X-ray spectroscopy （EDAX） and CIE chromaticity. The optimum synthesis conditions were obtained and reaction mechanism was further analyzed as well. The results show that molar ratio of S to Se, pH value and hydrothermal reaction conditions have great effects on the hues of the pigments. Pigments with vivid hues are obtained under the conditions that pH value is about 13.0, hydrothermal reaction condition is at 140 ℃ for 4 h or at 160 ℃ for 6 h. The reaction mechanism is that Se^2- of Cd（S1-xSex） substitutes S^2- of CdS and then forms a continuous solid solution.     

Microstructural Probing of （1-x） GeS2- x Ga2S3 System Glasses By Raman Scattering

Roman scattering measurement of （ 1 - x ） GeS2-x Ga2S3 system glasses was conducted in order to understand the microstructural change caused by the addition of Ga2S3 . According to the change of Raman spectra with the addition of Ga2S3, two main structural transformations were deduced ： the gradual enhancement of ethane- like structural units S3 Ge- GeS3 （ 250 cm ^- 1） and S3 Ga- GaS3 （270 cm ^- 1 ） and the appearance of charge imbalanced units [ Ga2 S2 （ S1/2 ）4 ]^2- and [Ga（ S1/2 ）4 ]^- . And this change of structural aspect seems to give as a clue to understanding the cause of the increased rare-earth solubility.     

Diffusion characteristic of sulfate anion in surface region of cement mortar at early stage

The SO_4~(2-)concentration distributions in surface region of cement mortar immersed in sulfate solution at early stage were measured by layered sampling method combined with chemical analysis, and the diffusion coefficients of SO_4~(2-)anions in surface region of mortar into internal area were calculated by means of instantaneous plane diffusion theory. The experimental results showed that the SO_4~(2-)concentration gradually reduced when the diffusion depth increased in the surface region of mortar. Diffusion coefficient(D) was relevant with the concentration and kind of environmental sulfate solution, which reduced with immersion time at the beginning, and then rose slowly after a period of time. The calculation of initial diffusion coefficient(D_0) and starting time of deterioration(t_∞) caused by sulfate attack was further attempted based on the data of diffusion coefficient, and it was found that D_0 and t∞ were all relevant with concentrations of sulfate and different kind of sulfate as well.     

Synthesis of glycerine-xanthate and its depressing mechanism in separation of marmatite from arsenopyrite

A small molecular organic depressor glycerine-xanthate was synthesized. The effect of glycerine-xanthate on the flotation of sulfide minerals was investigated based on a function of pH value and concentration of glycerine-xanthate through flotation experiments in the presence and absence of Cu^2＋. The results show that glycerinee-xanthate has a strong dressing effect on marmatite at pH〉6 and on arsenopyrite in weak acid and base conditions with butyl-xanthate as collector. In the presence of glycerine -xanthate, marmatite is activated by addition of Cu^2＋, but arsenopyrite cannot be activated and remains unfloatable. So the selective separation can be achieved for two minerals. The depression of glycerine-xanthate on sulfide minerals was discussed based on the radical electronegative calculation and the theory of HSAB. Infrared spectrum shows that there are some -OH and-CSS-in glycedne-xanthate molecule, which competes with butyl-xanthate on the mineral surface. As a result of many hydrophilic groups in glycerine-xanthate, the surfaces of marmatite and arsenopyrite become hydrophilic, thus the flotation of marmatite and arsenopyrite is depressed. The collector is adsorbed preferentially on the surface of marmatite and it shows a better floatability in the presence of Cu^2＋, whereas, the surface of arsenopyrite absorbs glycerine-xanthate and the flotation of arsenopyrite is depressed by glycerine-xanthate.     

Adsorption of sodium oleate at the microfine hematite/aqueous solution interface and its consequences for flotation

The adsorption of sodium oleate(NaOL) at the microfine hematite/aqueous solution interface was investigated in this paper. Experimental research indicated that negative effects stemmed from the dissolution of the microfine hematite(D50=19.21 μm) could be effectively eliminated via the appropriate dosage of NaOL at alkali pH conditions. Solution chemistry calculation and adsorption test results indicated that RCOO^- and(RCOO)₂^2- ions were responsible for microfine ...     

Improvement of copper–molybdenum ore beneficiation using a combined flotation and biohydrometallurgy method

The authors present the results of analysis of material composition and experimental investigations of acid and biohydrometallurgical leaching of middlings on grain size, pH level, leaching process duration, temperature and slurry density. The rational parameters of flotation and acid-bacterial leaching of middlings providing an efficient release of valuable components from mineral complexes and recovery to flotation concentrate and leaching solution have been determined. A combined flowsheet and a beneficiation process for bulk flotation middlings of copper–molybdenum ore have been suggested, which include middlings grinding, sulfide minerals flotation, bacterial leaching of sulfide flotation tailings, liquid-phase extraction of dissolved copper and electrolysis of re-extraction eluates. The suggested combined method of cleaning of middlings of copper–molybdenum ores beneficiation provides the total copper recovery increase by 0.8% with a reduction of the cost price of saleable material by 0.5%.     

Preparation and Performance of Si<Superscript>4+</Superscript>-doping Rod-shaped TiO<Subscript>2</Subscript> Powder by Nonhydrolytic Sol-gel Method

Titania (TiO₂) nanorod powder was prepared by nonhydrolytic sol-gel method using titanic chloride (TiCl₄) as titanium source, methylene dichloride (CH₂Cl₂) as solvent, absolute ethyl alcohol (CH₃CH₂OH) as oxygen donor. The effects of Si⁴⁺ doping on the TiO₂ nanocrystalline phase transformation temperature were systematically researched. The results showed that when the molar ratio of Ti⁴⁺ to Si⁴⁺ is 1 to1.3, TiO₂ prepared by calcination at 1100 °C for 1 hour exhibits rod shape and has good photocatalytic activity. Doping of Si⁴⁺ makes glass phase core-shell structure forming on the surface of anatase crystal particles, which can inhibit crystal phase transformation and raise the transformation temperature, making TiO₂ stable in anatase phase at 1200 °C.     

Assessment of pH-responsive nanoparticles performance on laboratory column flotation cell applying a real ore feed

Nanoparticles(NPs) can promote the column flotation process in mining industry. Nanoparticles' effects on column flotation process(copper recovery, grade and flotation rate constant) are assessed in Sarcheshmeh Copper Complex, Iran, through response surface methodology(RSM) optimization technique. The c-Al_2O_3, a-Fe_2O_3, SiO_2, and TiO_2 nanoparticles are selected for these experiments. A flotation rate constant is chosen as a response to assess the effect of nanoparticles on flotation in its kinetic sense.The process p H and nanoparticle dosage are selected as the influential parameters. Results obtained from RSM indicated that the maximum percentage of Cu recovery and grade is obtained at p H of 12 and nanoparticle dosage of 6 kg/t, through a-Fe_2O_3 and c-Al_2O_3 nanoparticles, respectively. Applying nanoparticles in particular c-Al_2O_3 and a-Fe_2O_3 increases the Cu recovery by 8–10% together with the grade by 3–6% in a significant manner. It is revealed that nanoparticles could effectively be applied in enhancing the flotation performance.