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1.
Managing mine water that has been contaminated with metal sulfide minerals due to galvanic corrosion is becoming an increasingly important environmental problem. Here, galvanic corrosion was investigated by studying galvanic interactions between pyrite–chalcopyrite and pyrite–galena in flowing mediums such as mine discharge water and flowing rainwater. The results showed that the corrosion current density of pyrite–galena is greater than that of pyrite–chalcopyrite under identical conditions. The corrosion current density of the galvanic cell tends to increase with increasing concentrations of strongly oxidizing ions (e.g., Fe3+) in the flowing medium, whereas the existence of non-oxidizing and non-reducing ions (e.g., Na+) have no obvious influence on the galvanic cell. In addition, the corrosion current density increases with increasing flow rate. Using the galvanic model, mixed potential theory and Butler–Volmer equation, the experimental results were explained theoretically. Because these experiments were performed under conditions very similar to those seen in mine discharge water and flowing rainwater, these results have direct implications for the future management and control of environmental pollution from mining operations. 相似文献
2.
金属硫化物矿物之间的原电池反应对于酸性矿山排水的形成、硫化物矿床的次生富集作用、地球电化学勘探以及湿法冶金过程等都有很重要的影响。通过改变溶液中氧化剂组分F e3 的浓度、pH值、溶液的流动状况以及溶液的盐度(如N a2SO4的浓度),采用精密的电流计和电位计,对作为阳极的黄铁矿与作为阴极的方铅矿所形成的原电池反应的电流密度和整个原电池的混合电位进行研究,结果表明:溶液中[F e3 ],pH值以及溶液的流动状况对黄铁矿和方铅矿之间原电池反应的影响很大,而溶液的盐度对反应的影响不是很显著。实验还发现,当黄铁矿电极表面存在微小裂纹时,其电极电位可降低至同条件下方铅矿的电极电位以下。这一实验结果在混合电位理论和Bu tler-V o lm er方程中得到了理论上的解释。 相似文献
3.
Galvanic interaction between galena and pyrite in an open system 总被引：1，自引：0，他引：1
1IntroductionMost sulfide minerals in nature have perfect con-ductivity and possess semiconducting properties.Gal-vanic corrosion may occur when two sulfide mineralswith different potentials are connected together in thesolution.The mineral with the highe… 相似文献
4.
In galvanic cell arrangements gold is electrochemically deposited on semiconducting sulfide minerals (pyrite, arsenopyrite, chalcopyrite) from aerated as well as H2S-saturated, gold-bearing 1 M KCl solutions. Observed cell potential differences of about 0.4–0.6 V in setups with one sulfide in aerated (cathode) and the other in H2S-saturated (anode) solutions are comparable with known self-potentials of natural sulfide ore bodies. Gold preferentially accumulates on the cathode, i.e. under oxidizing conditions. Linked sulfides of variable composition in the same environment, either oxidizing or reducing, yield potential differences up to 20 mV. Such assemblages simulate conditions typically occurring at surfaces of chemically inhomogeneous single crystals (e.g. zonation). Depending on chemical composition, sulfide minerals show either n- or p-type conductivity. Visible gold is preferentially accumulated on individual domains of sulfide surfaces that act as cathodes, i.e. p-type conductors in n-p junctions. The experimental results are discussed in view of electrochemical accumulation of visible gold on sulfides in nature. Arsenic is the most important element in establishing p-type conductivity of pyrite and arsenopyrite. This feature may explain why As is such a powerful pathfinder in gold exploration. 相似文献
5.
Electro-flotation tests were conducted on chalcopyrite particles with a modified Hallimond tube designed for electro-flotation, using platinum anode—copper cathode and graphite anode—copper cathode systems. Flotation tests were carried out for fines of chalcopyrite of size below 20 microns with potassium ethylxanthate as collector. Studies were done on flotation with hydrogen and oxygen separately with the usual variables. Dissolution of chalcopyrite at various current densities, with reagent at optimum conditions and without reagent was also studied. It is observed that electro-flotation particularly with oxygen, is effective in the flotation of fine particles of chalcopyrite. 相似文献
6.
Synthetic pyrite crystals doped with As, Co, or Ni, undoped pyrite, and natural arsenian pyrite from Leadville, Colorado were investigated with electrochemical techniques and solid-state measurements of semiconducting properties to determine the effect of impurity content on pyrite’s oxidation behavior. Potential step experiments, cyclic voltammetry, and AC voltammetry were performed in a standard three-electrode electrochemical cell setup. A pH 1.78 sulfuric acid solution containing 1 mM ferric iron, open to atmospheric oxygen, was chosen to approximate water affected by acid drainage. Van der Pauw/Hall effect measurements determined resistivity, carrier concentration and carrier mobility.The anodic dissolution of pyrite and the reduction of ferric iron half-reactions are taken as proxies for natural pyrite oxidation. Pyrite containing no impurities is least reactive. Pyrite with As is more reactive than pyrite with either Ni or Co despite lower dopant concentration. As, Co, and Ni impurities introduce bulk defect states at different energy levels within the band gap. Higher reactivity of impure pyrite suggests that introduced defect levels lead to higher density of occupied surface states at the solid-solution interface and increased metallic behavior. The current density generated from potential step experiments increased with increasing As concentration. The higher reactivity of As-doped pyrite may be related to p-type conductivity and corrosion by holes. The results of this study suggest that considering the impurity content of pyrite in mining waste may lead to more accurate risk assessment of acid producing potential. 相似文献
7.
Any conductive sulphide ore body can generate electrical ore potentials and this can be regarded as a geobattery, with an upper positive cathode and a lower negative anode. Two mechanisms which can occur simultaneously and which appear to explain these potentials are the oxygen concentration cell (OCC) and the sulphide galvanic cell (SGC). When there is a difference of O2 concentration between the cathode and anode, the OCC operates by contributing oxygen to the anode, and ceases when the difference is diminished. However, gradients of pH, temperature or pressure can keep the cell operating. In the SGC the sulphides dissolve at the anode (producing metal ions, sulphur and electrons), while at the cathode, either sulphides dissolve producing metal and sulphur ions, or reaction is as in the OCC. The ore potential measured in the field is the sum of the oxygen concentration cell and at times locally dominant sulphide galvanic cells. 相似文献
8.
Ran Liu Amy L. Wolfe David A. Dzombak Colin P. Horwitz Brian W. Stewart Rosemary C. Capo 《Applied Geochemistry》2009
Electrochemically controlled pyrite dissolution was performed with three pyrite materials from different geological origins under mixed potential and high overpotential conditions. Both solid electrodes and C paste electrodes of powdered pyrite were used. The rate of pyrite dissolution increased with applied positive potential and was strongly affected by temperature. Current density measurements over the applied potential range successfully described the rate of pyrite dissolution of each pyrite electrode. Controlled dissolution performed under mixed potential conditions on the solid electrodes successfully reflected the same pyrite reactivity and dissolution rate order as in batch reactor dissolution studies with the same pyrite materials. Therefore, the relative reactivity of different pyrite materials can be determined through current density measurements on their solid electrodes under mixed potential conditions. This technique could be a useful tool to compare rapidly the relative reactivity for different pyrite materials. In contrast, electrochemically controlled dissolution studies with C paste electrodes constructed with fine-grained pyrite and paraffin/graphite mixture did not result in accurate ranking of pyrite samples by dissolution rate. 相似文献
9.
Any conductive sulphide ore body can generate electrical ore potentials and this can be regarded as a geobattery, with an upper positive cathode and a lower negative anode. Two mechanisms which can occur simultaneously and which appear to explain these potentials are the oxygen concentration cell (OCC) and the sulphide galvanic cell (SGC). When there is a difference of O2 concentration between the cathode and anode, the OCC operates by contributing oxygen to the anode, and ceases when the difference is diminished. However, gradients of pH, temperature or pressure can keep the cell operating. In the SGC the sulphides dissolve at the anode (producing metal ions, sulphur and electrons), while at the cathode, either sulphides dissolve producing metal and sulphur ions, or reaction is as in the OCC. The ore potential measured in the field is the sum of the oxygen concentration cell and at times locally dominant sulphide galvanic cells. 相似文献
10.
H. Tan D. Feng J.S.J. van Deventer G.C. Lukey 《International Journal of Mineral Processing》2006,80(2-4):153-168
The anodic and cathodic behaviour of pyrite with clay and different carbon coatings of activated carbon, graphite and carbonaceous matter in cyanide medium was investigated using the potentiodynamic method. The presence of clay coating did not change the polarisation curve appearance for either the anodic oxidation of pyrite or the cathodic reduction of oxygen or the potential of the current plateau, but only decreased the plateau current especially at a higher coating thickness. The presence of the carbon coatings marginally shifted the rest potential for pyrite to a more anodic position and slightly changed the polarisation curve appearance for pyrite oxidation. The current density for pyrite oxidation largely increased in the presence of the carbon coatings, the potential at the plateau shifted to more cathodic positions, and the plateau width became smaller. These effects became more noticeable at a higher coating thickness. The activated carbon, graphite and carbonaceous matter coatings performed similarly in affecting pyrite oxidation at a similar thickness. The carbon coatings significantly increased the limiting current densities for oxygen reduction on pyrite, and the limiting current plateau became steeper at a higher coating thickness. The carbon coatings increased the limiting current density for oxygen reduction to a similar extent at a low coating thickness, but increased to varied extents at a higher coating thickness. The carbon coatings also greatly increased the cathodic current density for gold reduction on pyrite. The enhancement of pyrite oxidation and oxygen or gold reduction on pyrite by the carbon coatings was likely attributed to the electrochemical interaction between pyrite and the carbon materials with electron-rich surfaces and high conductivity. The presence of the carbon coatings significantly increased the oxidation of pyrite in aerated cyanide solutions and the preg-robbing of pyrite especially at a higher coating thickness. 相似文献
11.
The effect of sulfide concentrate mineralogy and texture on Reactive Oxygen Species (ROS) generation
The generation of Reactive Oxygen Species (ROS), H2O2 and OH, has been observed from sulfide mineral containing particles in acidic solutions. The implications of this phenomenon, as a potential microbial stress-causing effect, have been studied previously with respect to thermophilic bioleaching performance in the presence of finely milled pyrite and chalcopyrite concentrates. In this study, the effect of sulfide mineralogy on ROS generation in the absence of microbes under physicochemical conditions typical for the bioleach environment was investigated. The mineralogical and elemental composition of eleven different samples containing sulfide mineral was obtained. These Au, Cu and other base metal-containing sulfide mineral concentrates as well as a milled whole ore of low Cu grade were tested for ROS generation. The whole ore sample and two refractory Au concentrates containing approximately 50% pyrite, generated significantly less ROS compared to the base metal-containing concentrates when compared on a constant surface area loading basis. Sulfide mineral-related variables were correlated with ROS generation. A significant difference was observed between FeS2 and CuFeS2 grades separately, whereas a combined measure of both minerals present in samples showed a consistently strong correlation to ROS generation. The Cu grade, total Cu-containing sulfides and the chalcopyrite content of Cu-containing samples correlated well with ROS generation. However, a common deterministic variable with a strong association to increased ROS generation was not found. A sub-set of samples were subjected to QEMSCAN® for textural analysis. Results suggested that a decrease in sulfide mineral liberation, caused by gangue silicate mineral occlusion to solution, resulted in decreased reactivity as shown in one of the Au-containing samples. Well-liberated chalcopyrite and pyrite phases corresponded to increased reactivity of samples. Pyrite, which was present in all of the reactive samples, was shown to be associated with other sulfide minerals, implicating its importance in galvanic interactions. Micro-analysis of chalcopyrite and pyrite phases from highly reactive samples showed an abundance of particles with extensive cracking and the possible presence of secondary transformation phases (szomolnokite). These results suggest that sulfide mineralogy, liberation and extent of physical processing affect sulfide mineral concentrate reactivity in acidic solutions. 相似文献
12.
Polarograms have been determined with pyrite electrode in a buffer solution at pH 9.1, with and without potassium ethyl xanthate and dissolved air, and the resulting oxidation-reduction processes interpreted.It has been observed that the addition of dixanthogen in a nitrogenated solution does not produce any hydrophobicity at the surface of pyrite electrode and does not alter the rest potential and cathodic polarogram.The experimental observations and thermodynamic interpretations provide some support for the production of dixanthogen, developing the first hydrophobic layer, directly at the surface of the pyrite by the action of oxygen of air. 相似文献
13.
14.
以Pt为阳极,以Ti纳米管为基底修饰一薄层Pd和Cu构成的多金属纳米电极为阴极,搭建电化学反应器进行去除硝酸盐氮(NO3- N)研究,观察了在不同电流密度、初始浓度和pH值条件下该多金属纳米电极对NO3- N去除率的影响。结果表明,在电流密度为30 mA/cm2,添加050 g/L的 Na2SO4作为支持电解质的条件下,电解90 min后Cu Pd TiO2多金属纳米电极对硝酸盐的去除率可达81%,而相同条件下金属Ti做阴极时对硝酸盐的去除率仅为245%。溶液pH值的改变对 NO3- N的去除效果几乎没有影响;随着电流密度的增高,NO3- N的去除效率也随之提高;而随着溶液初始浓度的升高,NO3- N的去除率反而略有下降。 相似文献
15.
研究发现,通电作用下冻土中的未冻水会发生迁移,这种持续的迁移是一个复杂的物理化学过程,并最终伴随着冻胀的过程。为了探究这一电场作用对冻土的影响,选取冻结冻胀敏感性较高的粉质兰州黄土作为研究对象,分析其在3、4和5 V?cm-1电势梯度作用下的阴阳极变形量、通电前后水分分布规律和电流及电能损耗。结果表明：随着电势梯度的增大,土体阴阳极变形量的差值逐渐增大,且阴极都发生膨胀,阳极发生沉降;随着电势梯度的增大,水分由阳极至阴极的迁移量增大,电流降低的幅度增大,两者变化特征与含水率差值变化特征类似;在5 V?cm-1的电势梯度下,电能总能耗最大,单位含水率能耗最小。 相似文献
16.
Tseluyko A. S. Maslennikov V. V. Ayupova N. R. Maslennikova S. P. Danyushevsky L. V. 《Geology of Ore Deposits》2019,61(2):133-161
At the well-preserved Yubileynoe VMS deposit (Southern Urals), sulfide breccias and turbidites host abundant tellurides represented by hessite, coloradoite, altaite, volynskite, stützite, petzite, and calaverite, as well as phases of the intermediate tellurobismuthite → rucklidgeite solid solution. Three telluride generations were highlighted: (1) primary hydrothermal tellurides in fragments of chalcopyrite and sphalerite of chalcopyrite-rich black smoker chimneys; (2) authigenic tellurides in pseudomorphic chalcopyrite and chalcopyrite veins after fragments of colloform and granular pyrite; and (3) authigenic tellurides in pyrite nodules. Authigenic tellurides are widespread in pyrite-chalcopyrite turbidites. Primary hydrothermal and authigenic tellurides are less common in sulfide turbidites and gritstones with fragments of sphalerite-pyrite, pyrite-sphalerite paleosmoker chimneys and clasts of colloform and fine-grained seafloor hydrothermal crusts. Siliceous siltstones intercalated with sulfide turbidites contain pyrite nodules, whose peripheral parts contain inclusions of epigenetic tellurides. It is assumed that Te for authigenic tellurides originated from fragments of colloform pyrite and hydrothermal chalcopyrite of pyrite-chalcopyrite chimneys, which dissolved during the postsedimentation processes. The main Te concentrators in clastic ores include pseudomorphic chalcopyrite, which inherits high Te, Bi, Au, Ag, Co, Ni, and As contents from the substituted colloform pyrite, and varieties of granular pyrite containing microinclusions of tellurobismuthite (Bi, Te), petzite (Au, Ag, Te), altaite (Pb, Te), coloradoite, and hessite (Ag, Te).
相似文献17.
铜厂铜-铁矿床在成矿时代、成矿物质来源及矿床成因等方面存在较大争议,限制了其成矿模式的建立以及进一步的找矿实践. 利用黄铜矿Re-Os同位素对该矿床进行定年,并利用LA-MC-ICP-MS技术对黄铜矿、黄铁矿及磁黄铁矿等硫化物开展原位硫同位素研究. 分析结果显示,5件黄铜矿Re-Os同位素等时线年龄为484±34 Ma（MSWD=8.7）,表明铜厂铜-铁矿床形成于早古生代加里东期. 铜厂铜-铁矿床上部铜矿床中黄铜矿（+9.75‰~+13.1‰）和黄铁矿（+9.22‰~+13.9‰）的δ34S值略高于下部铁矿床中黄铜矿（+8.66‰~+10.9‰）、黄铁矿（+8.85‰~+11.0‰）和磁黄铁矿（+7.93‰~+9.28‰）. 计算得到早期成矿热液的δ34S∑S值约为+10.6‰,晚期成矿热液的δ34S∑S值约为+12.3‰,说明矿床硫是地幔硫混染海水硫形成的,热化学还原在海水硫酸盐还原过程中起到关键作用. 铜厂铜-铁矿床的形成可分为两期:新元古代晋宁期,Rodinia超大陆裂解导致勉略宁地区发生海底火山喷发形成富含Fe、Cu的初始矿源层;早古生代加里东期,大陆边缘持续的裂解和裂陷形成勉略海槽并导致强烈的岩浆活动,富含挥发分及硫的岩浆热液混合海水硫,并从细碧岩中萃取Fe、Cu等成矿物质,早期成矿热液在铜厂地区深部形成铁矿床,随着磁铁矿和硫化物的沉淀,成矿热液演化到晚期阶段并沿断裂构造带向上运移,在铜厂地区浅部形成铜矿床. 相似文献
18.
《International Geology Review》2012,54(2):202-211
An experimental study of sulfide ores shows that some of the elements in the mineral can go into solution by virtue of the action of an “electrolytic cell,” in which the mineral with the higher charge serves as the cathode and the mineral with the lower charge serves as the anode. — M.E. Burgunker 相似文献
19.
胶东地区招贤深部金矿床金和载金矿物化学成分及其地质意义 总被引：1，自引：1，他引：0
胶东地区-1000 m以下深部找矿的重大突破,使得探明储量已达5000多t,成为探讨深部金的赋存状态及成矿作用的天然实验室。招贤金矿为焦家成矿带近年深部找矿重大突破之一,矿体主要产于-1260 m以深的晚侏罗世二长花岗岩中,受控于焦家断裂。金属矿物主要为黄铁矿、黄铜矿和银金矿等,脉石矿物包括石英、绢云母、方解石、钾长石等。围岩蚀变以钾长石化、硅化、黄铁绢英岩化、碳酸盐化为主。金矿物以自然金和银金矿为主,呈裂隙金或包体金分布于黄铁矿中,少数不可见金呈晶隙金分布于黄铁矿等矿物中。其中,黄铁矿w(S)=52.227%～54.915%、w(Fe)=44.749%～47.134%,原子个数比S/Fe=1.99～2.11,化学式FeS1.99～FeS2.11;黄铜矿w(S)=34.282%～35.140%、w(Fe)=29.263%～30.268%,w(Cu)=33.130%～34.114%,化学式Cu0.96FeS2.01～Cu1.01FeS2.10,平均化学式为C... 相似文献
20.
金属矿物的反应动力学与地球化学意义 总被引：8，自引：0，他引：8
概述了动力学实验的技术方法和金属矿物的反应动力学研究进展。动力学实验使用的三种基本化学反应装置是间歇反应器（ＢＲ）、活塞流反应器（ＰＦＲ）和混合流反应器（ＭＦＲ）,确定速率定律的数学方法包括积分法、微分法和混合法,以微分法中的初始速率法应用最广。目前主要研究了水溶液中黄铁矿氧化、黄铁矿和黄铜矿形成、晶质铀矿和磁铁矿溶解的速率定律和反应机理,发现：（１）酸性溶液中黄铁矿的氧化速率对Ｆｅ３＋和Ｏ２浓度呈分数依赖并受表面反应的控制;（２）低于３００℃时黄铁矿不能从溶液中直接成核,而需初始地通过ＦｅＳ先驱物的硫化生成,ＦｅＳ与Ｈ２Ｓ反应形成黄铁矿的速率方程为二级;（３）磁黄铁矿或黄铁矿与Ｃｕ２＋反应均可形成黄铜矿,前者经历了一系列准稳的Ｃｕ Ｆｅ硫化物的中间物,后者的速率方程为表观一级并受表面反应的控制;（４）酸性ｐＨ时磁铁矿的非线性溶解行为可采用表面反应扩散输运耦合的收缩核模型（ＳＣＭ）来描述。有关动力学实验成果完善和深化了对矿床中黄铁矿、黄铜矿的形成机理和风化壳中磁铁矿的稳定性等方面的认识。将来的实验研究将向更多的金属矿物和高温高压领域发展。 相似文献