钢基体表面空气助燃超音速火焰喷涂制备铁黄铜涂层的组织和性能

采用空气助燃超音速火焰喷涂技术在30CrMnSi钢基体表面上制备出厚3 mm的HFe59-1-1铁黄铜涂层,对涂层的化学成分、物相组成、显微硬度及耐磨性能进行了研究。结果表明:制备的铁黄铜涂层呈层状结构,晶粒细小,致密度高,孔隙率小于1%,和基体结合强度高,显微硬度为241 HV,且表现出比同牌号铸造铁黄铜更为优良的耐磨性能。

低品位高铁黄铜矿的细菌堆浸试验研究

大红山低品位高铁黄铜矿２ｔ规模细菌溶浸提取铜的试验结果表明，经过１２０ｄ的堆浸，铜的浸出率可达１４．２％，细菌的活性及氧化性能好，浸出参数选择合理。该工艺流程畅通，可作为１５００ｔ井下堆浸的设计基础。

四六铁黄铜筒形件热反挤压表面重皮与气泡缺陷的分析

分析了四六铁黄铜热反挤压筒形件表面重皮、气泡等缺陷与工艺参数之间的关系及缺陷产生的机理,提出了选择合理的加热温度、挤压速度、减少饼料表面缺陷,合理润滑,严格执行工艺操作规程的预防措施,消除了制件缺陷。

4-偶氮变色酸苯基荧光酮与铝显色反应的研究及应用

在表面活性剂ＣＴＭＡＢ存在下，研究了新显色剂４－偶氮变色酸苯基荧光酮（ＡＣＡＰＦ）与铝的显色反应及分光光度测定．在ｐＨ６的ＨＡｃ－ＮａＡｃ缓冲溶液中，铝（Ⅲ）与显色剂形成１：２的络合物，络合物最大吸收波长为５５８ｎｍ，表观摩尔吸光系数－１．０８×１０５．铝（Ⅲ）浓度在０～６．５μｇ／２５ｍＬ范围符合比尔定律．拟定方法用于铝铁黄铜及石灰石样品中微量铝的测定，结果满意．

Effect of EPS on adhesion of Acidithiobacillus ferrooxidans on chalcopyrite and pyrite mineral surfaces

Extracellular polymeric substances （EPS） were extracted from Acidithiobacillus ferrooxidans through sonication method associated with centrifugation, which was evaluated tentatively with 2-keto-3-deoxyoctonic acid （KDO） as the indicator of EPS by spectrophotometry. Then the effect of EPS of A. ferrooxidans on the adhesion on chalcopyrite and pyrite surfaces was studied through a series of comparative experiments. The untreated cells and EPS-free cells of A. ferrooxidans were mixed with EPS suspension, Fe^2＋ or Fe^3＋, respectively. The planktonic cells were monitored in 2 h during bioleaching. The results indicate that the presence of EPS on the cell is an important factor for the adhesion to chalcopyrite and pyrite. A decrease of attachment of A. ferrooxidans to minerals was produced by the deficiency of EPS, which can recover mostly when the EPS was re-added into the EPS-free cells. The restoring extent is more obvious in pyrite than in chalcopyrite. The extent of cell adhesion to chalcopyrite increased when EPS and Fe^3＋ added, and decreased when Fe^2＋ added, which imply the electrostatic interaction plays a main role in initial adhesion between bacteria and minerals and it is a driving force for bacteria to produce EPS probably as a result of regaining their attachment ability to copper sulphides.

Relationship and effect of redox potential,jarosites and extracellular polymeric substances in bioleaching chalcopyrite by acidithiobacillus ferrooxidans

The changes of pH,redox potential,concentrations of soluble iron ions and Cu^2＋ with the time of bioleaching chalcopyrite concentrates by acidithiobacillus ferrooxidans were investigated under the different conditions of initial total-iron amount as well as mole ratio of Fe（III） to Fe（II） in the solutions containing synthetic extracellular polymeric substances （EPS）.When the solution potential is lower than 650 mV （vs SHE）,the inhibition of jarosites to bioleaching chalcopyrite is not vital as EPS produced by bacteria can retard the contamination through flocculating jarosites even if concentration of Fe（III） ions is up to 20 g/L but increases with increasing the concentration of Fe（III） ions;jarosites formed by bio-oxidized Fe3＋ ions are more easy to adhere to outside surface of EPS space on chalcopyrite;the EPS layer with jarosites acts as a weak diffusion barrier to further rapidly create a high redox potential of more than 650 mV by bio-oxidizing Fe^2＋ ions inside and outside EPS space into Fe^3＋ ions,resulting in a rapid deterioration of ion diffusion performance of the EPS layer to inhibit bioleaching chalcopyrite severely and irreversibly.

Interaction mechanism of Cu^(2+),Fe^(3+) ions and extracellular polymeric substances during bioleaching chalcopyrite by Acidithiobacillus ferrooxidans ATCC2370

The extracellular polymeric substances（EPS） of Acidithiobacillus ferrooxidans ATCC 23270,and iron and copper enclosed in EPS were extracted by ultrasonication and centrifugation methods to determine the interaction mechanism of Cu2＋,Fe3＋ and EPS during bioleaching chalcopyrite.Generally,Cu2＋ ions can stimulate bacteria to produce more EPS than Fe3＋ ions.The mass ratio of Fe3＋/Cu2＋ enclosed in EPS decreased gradually from about 4：1 to about 2：1 when the concentration of Cu2＋ ions increased from 0.01 to 0.04 mol/L.The amount of iron and copper bound together by EPS in ferrous-free 9K medium containing 1% chalcopyrite was about 2 times of that in 9K medium containing 0.04 mol/L Cu2＋ ions.It was inferred that the EPS with jarosites on the surface of chalcopyrite gradually acted as a weak diffusion barrier for Cu2＋,Fe3＋ ions transference during bioleaching chalcopyrite.

Surface characterization of chalcopyrite interacting with Leptospirillum ferriphilum

The alteration of surface properties of chalcopyrite after biological conditioning with Leptospirillum ferriphilum was studied by adsorption,zeta-potential,contact angle and bioleaching tests.The strains of L.ferriphilum cultured using different energy sources（either soluble ferrous ion or chalcopyrite） were used.The adhesion of bacteria to the chalcopyrite surface was a fast process.Additionally,the adsorption of substrate-grown bacteria was greater and faster than that of liquid-grown ones.The isoelectric point（IEP） of chalcopyrite moved toward that of pure L.ferriphilum after conditioning with bacteria.The chalcopyrite contact angle curves motioned diversely in the culture with or without energy source.The results of X-ray diffraction patterns（XRD）,scanning electron microscopy（SEM） and energy-dispersive X-ray spectroscopy（EDS） analysis indicate that the surface of chalcopyrite is covered with sulfur and jarosite during the bioleaching process by L.ferriphilum.Furthermore,EDS results imply that iron phase dissolves preferentially from chalcopyrite surface during bioleaching.The copper extraction is low,resulting from the formation of a passivation layer on the surface of chalcopyrite.The major component of the passivation layer that blocked continuous copper extraction is sulfur instead of jarosite.

Effect of pH values on extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans during chalcopyrite bioleaching

The effect of pH values on the extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans was comparatively investigated in different phases of bacterial growth during chalcopyrite bioleaching. The results indicate that the extracellular protein is always more than the extracellular polysaccharide secreted by attached cells on the chalcopyrite, on the contrary, and is always less than the extracellular polysaccharide secreted by free cells in the solution at bacterial adaptive phase, logarithmic phase and stationary phase whenever pH value is at 1.0, 1.5, 2.0 or 2.5; free cells are mainly through the secretion of extracellular polysaccharide rather than the extracellular protein to fight against disadvantageous solution environment, such as high concentration of metal ions and unsuitable pH solution; both amounts of polysaccharide and protein secreted by attached cells are mainly positively related to the solution acidity rather than the total concentration of soluble metal ions. The experimental results imply that bacteria are mainly through secreting more extracellular polysaccharide to fight against disadvantageous environment and the extracellular protein perhaps plays an important role in oxidation？reduction reactions in the bioleaching system.

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Enrichment of ferric iron on mineral surface during bioleaching of chalcopyrite

In order to investigate the enrichment of ferric iron bound by extracellular polymeric substance （EPS） on the mineral surface during bioleaching of chalcopyrite, several methods including sonication, heating and vortexing were used and sonication at 48℃ was shown as a good way to extract ferric iron. Scanning electron microscope （SEM） and energy dispersive X-ray spectrometer （EDX） analysis showed that lots of cracks and pits can be found on the chalcopyrite surface after bioleaching and that iron oxide was filled in these cracks and pits. The variations of contents of ferric iron and EPS on the chalcopyrite surface were investigated. The results indicated that the content of EPS increased rapidly in the first 10 d and then maintained at a stable level, while ferric iron content increased all the time, especially in the later stage of bioleaching.

Xanthate interaction and flotation separation of H2O2-treated chalcopyrite and pyrite

This study investigated the effects of H2O2 treatment on xanthate interaction and flotation separation of chalcopyrite and pyrite by making use of a series of laboratory flotation experiments and surface analysis techniques.Flotation test results showed that H2O2 treatment influenced the flotation behaviors of the two minerals;however,flotation of pyrite was depressed more significantly than that of the chalcopyrite.Under well-controlled H2O2 concentration,the selective separation of chalcopyrite from pyrite was realized at pH 9.0,at which the recovery of chalcopyrite was over 84%and that of pyrite was less than 24%.Zeta potential,UV-visible and IR spectrum measurements revealed that the collector interacted differently with the two minerals after H2O2 treatment,and the surface of chalcopyrite adsorbed much greater amount of xanthate than that of the pyrite.IR and XPS analyses showed that the H2O2 treatment significantly changed the surface properties of pyrite to very hydrophilic species that inhibited the adsorption of collector and thus depressed the floatability of pyrite.While,the surface of chalcopyrite remained mildly inert to H2O2,as a result,the adsorption of xanthate and its oxidation to dixanthogen were very effective,which enhanced the flotation of chalcopyrite.

Influences of collector DLZ on chalcopyrite and pyrite flotation

The interaction mechanism of collector DLZ in the flotation process of chalcopyrite and pyrite was investigated through flotation experiments,zeta potential measurements and infrared spectrum analysis.Flotation test results indicate that DLZ is the selective collector of chalcopyrite.Especially,the recovery of chalcopyrite is higher than 90% in neutral and weak alkaline systems,while the recovery of pyrite is less than 10%.When using CaO as pH regulator,at pH=7-11,the floatability of pyrite is depressed and the recovery is less than 5%.Zeta potential analysis shows that the zeta potential of chalcopyrite decreases more obviously than that of pyrite after interaction with DLZ,confirming that collector DLZ shows selectivity to chalcopyrite and pyrite.And FTIR results reveal that the flotation selectivity of collector DLZ is due to chemical absorption onto chalcopyrite surface and only physical absorption onto pyrite surface.

Mechanism of sodium sulfide on flotation of cyanide-depressed pyrite

The mechanism of sodium sulfide(Na2S)on the flotation of cyanide-depressed pyrite using potassium amyl xanthate(PAX)as collector was investigated by flotation test and electrochemical measurements.The flotation results show that both PAX and Na2S can promote the flotation recovery of cyanide-depressed pyrite and their combination can further improve the pyrite flotation recovery.Electrochemical measurements show that PAX and Na2S interacted with cyanide-depressed pyrite through different mechanisms.PAX competed with cyanide and was adsorbed on the pyrite surface in the form of dixanthogen,thus enhancing the hydrophobicity and flotation of cyanide-depressed pyrite.Unlike PAX,Na2S rendered the pyrite surface hydrophobic through the reduction of ferricyanide species and the formation of elemental sulfur S0 and polysulfide Sn2-.The combined application of PAX and Na2S induced superior pyrite flotation recovery because of a synergistic effect between PAX and Na2S.

Bioleaching and dissolution kinetics of pyrite,chalcocite and covellite

In this work,the bioleaching process of pyrite,chalcocite and covellite which were the main phase compositions for Zijin copper mineral was comprehensively studied.The influence parameters,such as leaching temperature,Fe^(3+)concentration,pH of solution and bacteria concentration were investigated.The leaching kinetics of the pyrite,chalcocite and covellite under the studied conditions was successfully modeled by an empirical diffusion-like equation,respectively.The apparent activity energy of pyrite leaching,chalcocite leaching(stage Ⅱ)and covellite leaching was calculated to be 69.29,65.02 and 84.97 kJ/mol,respectively.

Flotation and electrochemical behaviors of chalcopyrite and pyrite in the presence of N-propyl-N′-ethoxycarbonyl thiourea

The characteristics of N-propyl-N′-ethoxycarbonyl thiourea（PECTU） were studied in the flotation experiments of chalcopyrite and pyrite compared with butyl xanthate（BX）. The interaction mechanism between mineral and PECTU was investigated according to zeta potential and electrochemistry measurements in the presence of PECTU. The results proved that PECTU performed a stronger ability to capture chalcopyrite and a better selectivity against pyrite. The zeta potential of chalcopyrite was positively shifted after interacting with PECTU, which indicated that the collector PECTU was obviously adsorbed on chalcopyrite surface. The cyclic voltammetry and Tafel curves results indicated that the oxidation and corrosion rates of chalcopyrite surface were limited in the presence of PECTU, while the effect of PECTU on pyrite in weak alkaline solution can be neglected basically according to the results of zeta potential and electrochemical tests.

Ultrasonic-enhanced selective sulfide precipitation of copper ions from copper smelting dust using monoclinic pyrrhotite

The sulfide passivation film produced on the surface seriously prevents further reaction in the process of using monoclinic pyrrhotite(MPr)to treat heavy metal ions in wastewater.Ultrasonic technology was introduced to assist MPr to recover the copper ions.XPS result proves that CuS products exist on the surface of MPr.XRD and SEM results show that the CuS on the particles’surface is stripped under ultrasonic condition.The kinetics results indicate that the reaction under both conventional and ultrasonic conditions conform to the Avrami model.The reaction process changes from diffusion control to chemical reaction control under the ultrasonic condition as the solid layer is stripped off.The presence of ultrasonic significantly reduces the acidity and temperature required for the reaction and enhances the utilization efficiency of MPr;by controlling the amount of MPr,the removal rates of copper and arsenic in copper smelting dust leachate exceed 99%and 95%,respectively.

Separation of chalcopyrite and pyrite from a copper tailing by ammonium humate

Copper tailings constitute a large proportion of mine wastes. Some of the copper tailings can be recycled to recover valuable minerals. In this paper, a copper tailing was studied through the chemical analysis method, Xray diffraction and scanning electron microscope-energy dispersive spectrum. It turned out that chalcopyrite(Cu) and pyrite(S) were the main recoverable minerals in the tailing. In order to separate chalcopyrite from pyrite in low pulp pH, ammonium humate(AH) was singled out as the effective regulator. The depression mechanism of AH on the flotation of pyrite was proved by FTIR spectrum and XPS spectrum, demonstrating that there was a chemical adsorption between AH and pyrite. By Response Surface Methodology(RSM), the interaction between AH, pulp pH and iso-butyl ethionine(Z200) was discussed. It was illustrated that the optimal dosage of AH was 1678 g·t^(-1) involving both the recovery of Cu and S. The point prediction by RSM and the closed-circuit flotation displayed that the qualified Cu concentrate and S concentrate could be obtained from the copper tailing.The study indicated that AH was a promising pyrite depressor in the low pulp pH from copper tailings.

Characterization and kinetic study on ammonia leaching of complex copper ore

Ammonia leaching kinetics of a complex Cu-ore assaying 8.8% Cu and 36.1% Fe was examined. Mineralogical characterization indicated that the major phase of the ore was siderite with chalcopyrite as the major sulfide mineral. The effects of parameters such as agitation, temperature, NH3 concentration, particle size and oxygen partial pressure （Po2） were investigated. Under the standard leaching conditions of 125-212 μm particle size, 120 ℃, 1.29 mol/L NH3 and 202 kPa ofpo2, about 83% Cu could be selectively extracted in 2.5 h. However, when using higher NH3 concentration and lower particle size, more than 95% extraction was achieved. The leaching process was found to be surface reaction controlling. The estimated activation energy was （37.6±1.9） kJ/mol and empirical orders of reaction with respect topos and [NH3] were about 0.2 and 1, respectively.

Influence diversity of extracellular DNA on bioleaching chalcopyrite and pyrite by Sulfobacillus thermosulfidooxidans ST

In this paper,Sulfobacillus thermosulfidooxidans ST was selected for use in bioleaching of pyrite and chalcopyrite.The adsorption experiments revealed that more cells were adsorbed on the surface of pyrite than on the surface of chalcopyrite.The role of extracellular DNA(eDNA)in the bioleaching process was investigated by depletion of eDNA using DNase I.The number of cells attached on the chalcopyrite and pyrite surfaces decreased on a large scale,and the lag phase of cell growth increased,causing the leaching percentages of pyrite and chalcopyrite to decrease by approximately 11.6%and 20.5%,respectively.The formation and distribution of eDNA secreted during bioleaching was assessed by a fluorescent dye-based method and visualized by confocal laser scanning microscopy(CLSM).The content of eDNA increased with bioleaching time.Furthermore,ST showed a stronger capacity to produce eDNA on the surface of pyrite than on the surface of chalcopyrite.These results showed that the removal of eDNA has a more significant effect on the bioleaching of chalcopyrite than on pyrite.