氨性溶液中砷黄铁矿阳极氧化过程的电化学

通过电化学研究 ,考察了氨溶液中砷黄铁矿的阳极氧化反应。实验表明氧化生成的表面膜对反应有抑制作用 ,该膜具有多孔性 ,可使反应继续进行。低温时 ,阳极氧化过程由电化学反应控制 ;高温时 ,反应受扩散过程控制。氨浓度对氧化过程的反应速率没有显著影响 ,溶液中Cu2 能降低氧化峰电位 ,改变氧化表面膜的形态 ,使膜的孔隙增大 ,反应速度加快。砷黄铁矿的阳极氧化总反应为FeAsS 11H2 O =Fe(OH) 3 SO2 -4 HAsO2 -4 18H 14e。     

砷黄铁矿在催化氧化酸浸体系中的反应

着重研究了砷黄铁矿在ＨＮＯ３－Ｈ２ＳＯ４－Ｏ２水溶液体系中氧化酸浸的动力学规律，考察了反应过程中产物分布、操作变数及几种添加物对氧化浸取速率的影响。研究表明硝酸浓度、初始酸度和粒度是控制体系反应速率最重要的因素；反应产物Ｓｏ的形成并不影响氧化反应的继续进行。实验结果可用收缩末反应芯模型１－（１－ａ）１／３＝ｋｔ来表达；测得的体系表现活化能值为２３．６ｋＪ／ｍｏｌ。     

X80钢及其焊缝组织在酸性土壤中的电化学行为

通过动电位扫描和电化学阻抗技术,研究了X80钢在酸性腐蚀介质中的腐蚀过程。并用CHI电化学工作站和Zsimpwin软件对试验结果进行了拟合。结果表明,X80管线钢及焊接接头在鹰潭土壤模拟溶液中的极化曲线都具有活性溶解特征,焊缝的耐蚀性大于母材。这是由于焊缝经过焊接热作用后,掺入了某些耐腐蚀的合金元素,使焊缝的耐蚀性增强。     

Ni-P-CNTs化学镀层在酸性溶液中的电化学腐蚀行为

为了更深地认识CNTs对Ni—P镀层电化学腐蚀性能的影响,采用复合化学镀技术,通过向优化的化学镀溶液中加入碳纳米管的方法在45^#钢基材上制备了Ni—P—CNTs复合镀层,并用相同工艺在45^#钢基材上直接化学镀Ni—P镀层作为对比。采用SEM／EDAX,XRD和TEM综合分析了复合镀层的形貌和结构,分析表明：所得镀层以非晶结构为主,碳纳米管均匀分布在镀层中。采用动电位极化及交流阻抗技术对比研究了Ni—P—CNTs复合镀层及纯Ni—P镀层在0．5mol／LNaCl＋0．05mol／LH2sO4酸性溶液中的电化学腐蚀行为,腐蚀实验结果表明：在该介质溶液中,与不含碳纳米管的Ni—P镀层相比,Ni—P—CNTs复合镀层的自腐蚀电位和自腐蚀电流密度较低,耐均匀腐蚀性能得到明显改善;此外,碳纳米管的加入还明显提高了Ni—P镀层在该介质溶液中的耐点蚀性能。     

硫化氢对不锈钢在酸性体系中腐蚀行为影响的研究

采用动电位扫描、电化学阻抗和电子探针等方法，研究了硫氢浓度对1Cr18Ni9Ti不锈钢在0．05mol/LH2SO4体系中的腐蚀行为的影响，结果表明：（1）随硫化氢浓芳的增加，1Cr18Ni9Ti不锈钢的腐蚀被加速，钝化区变窄，且维钝电流密度变大；（2）硫化氢的加入使不锈钢表面钝化膜被破坏，随硫化氢浓度的增加，钝化膜有一个从减薄到完全破坏的过程。     

在酸性介质中敏化1Cr18Ni9Ti不锈钢钝化膜的光电化学研究

利用光电化学和电化学测试技术研究了敏化的不锈钢的钝化膜。对敏化的不锈钢电极,在不同的电极电势范围内,钝化膜显示出n-型或p-型半导体的特性。这些光电化学行为的不同可以用不同电极电势下不锈钢钝化膜组成中Cr(Ⅲ)水合程度的不同来解释。     

用硫酸铁浸出预处理含金的砷黄铁矿精矿

生物氧化可作为含金硫化矿的预处理方法，其药剂费用低，对环境保护也很有意义。然而，该法的动力学缓慢，反应时间长，因此操作费用很高，如何通过间接接触的方法进行生物氧化，并且将化学和生物两种作用有效地分成两个作业，则其反应动力学将会得到改善，两个作业分别为：（１０用三价铁进行硫化物的化学反应；（２）所产生的二价铁的生物氧化。     

采用就地矿浆氧化法从难处理砷黄铁矿精矿中回收金

含金砷黄铁矿是一种主要的不适于焙烧的难处理金矿物。生物氧化法是一种颇受欢迎的处理方案,但反应速度较慢并需要严格控制给料中砷的含量。在实验室规模一,作为一种可能的处理方法,在膜片槽反应器的酸化盐水中,研究了用氯进行的电化学矿浆氧化法,用含砷黄铁矿（ＦｅＡｓＳＷ）,黄铁矿（ＦｒＳ２）和辉砷我放（ＮｉＡｓＳ）的难处理精矿（可氰化的金含量约７％）,试验表明,金回收率可达９０％以上,反应速度比生物氧化法快得     

X100管线钢在水饱和酸性土壤中的电化学阻抗谱特征

利用电化学阻抗谱(EIS)研究X100管线钢在水饱和酸性土壤中短期的电化学腐蚀行为。结果表明,X100管线钢在鹰潭水饱和土壤中浸泡104 h后已产生点蚀。腐蚀过程的EIS谱具有两个时间常数特征,高频区为代表反应的容抗弧,低频区为代表吸附或点蚀形核期产生的感抗弧。腐蚀初期(1 h～33 h),由于水饱和土壤介质电导率较低,电极反应过程受扩散控制;腐蚀产物在电极表面积累对反应离子扩散有阻碍作用,使阻抗增大;腐蚀产物膜疏松多孔,形成局部活化区域,使阻抗减小;Cl~-对腐蚀产物膜有破坏作用且在膜内局部地区浓缩,诱发点蚀,使阻抗减小,出现感抗特征。     

在酸性介质中聚苯硫醚对钯的吸附行为

研究了聚苯醚硫（ＰＰＳ）在硝酸、硫酸和盐酸介质中对贵金属钯的吸附行为及振荡吸附时间、酸度、钯浓度对吸附的影响。结果表明：在不同的酸介质中ＰＰＳ对钯均有一定量的吸附，其饱和吸附容量可达１０．７８±１．０９ｍｇ／ｇ树脂，且有很好的吸附选择性，还探索了解吸剂及从混合离子溶液中回收钯的途径。     

Galvanic effect of magnetite on electrochemical oxidation of arsenopyrite in acidic culture medium

The galvanic interaction of arsenopyrite—magnetite in acidic culture medium was investigated by electro- chemical measurements, X-ray photoelectron spectroscopy characterization and leaching experiments. The results indicated that the rest potential of magnetite was 321 mV, which was more anodic than 223 mV of arsenopyrite, and the galvanic current was 7.40 µA, verifying the existence of the galvanic interaction between arsenopyrite and magnetite. The galvanic potential and polarization curves suggested that the redox behaviors of arsenopyrite dominated the overall galvanic interaction. The galvanic interaction enhanced the electrochemical dissolution of arsenopyrite with the generation of more oxidation products (S⁰, SO₃^2—, SO₄^2— and AsO₃^3—) on arsenopyrite and an increase in the chemical reactivity of the surface. Leaching experiments of 6 days showed that the presence of magnetite improved the arsenic release from arsenopyrite by 30 mg/L, and further confirmed the enhanced oxidation of arsenopyrite when coupled with magnetite.     

Bio-oxidation of arsenopyrite

Oxidation of arsenopyrite with Acidithiobacillus ferrooxidans was studied. The electrochemical results show that arsenopyrite is firstly oxidized to As2S2 at the potential of 0.2-0.3 V （vs SHE） and As2S2 covers the electrode and retards the process continuously. While at higher potential over 0.3 V （vs SHE）, AszS2 is oxidized to H3AsO3, and H3AsO3 is then oxidized to H3AsO4 at 0.8 V （vs SHE）. The leaching results show that the addition of FeS2 can promote the oxidation of As^3＋ to As^5＋ and increase the activity of the bacteria. The best bio-oxidation technical parameters are the initial pH of 1.8-2.0, particle sizes less than 0.074 mm, temperature in the range of 25-30℃ and rotating speed of the orbital incubator of 100-160 r/min. The results provide theoretical and technological supports of bio-oxidation arsenopyrite for pretreating refractory arsenic gold ores.     

Electrochemical behavior of aluminium in acidic media

The inhibitive action of the acid extracts of seeds' leaves and bark from the Ficus virens plant towards hydrochloric and sulfuric acid corrosion of aluminium is tested using mass loss and thermometric techniques. It was found that the extract acts as a good corrosion inhibitor for aluminium corrosion in all concentration of hydrochloric and sulfuric acid solution. The ellagic acid has been used as a representative of the tannin species. The tannins are anodic inhibitors. The inhibition efficiency (IE) increases as the extract concentration is increased. The effect of temperature on the IE was studied. It was found that the presence of extract increases the activation energy of the corrosion reaction. Moreover, the heat of adsorption (Q_ads) was also calculated. It was found that the Ficus virens extract provides a good protection against pitting corrosion in chloride ion containing solution.     

黄铁矿对砷黄铁矿生物浸出的影响

为探明黄铁矿在砷黄铁矿生物浸出过程中的作用与影响,选择纯黄铁矿和砷黄铁矿组成的矿浆浸出体系,考察黄铁矿和砷黄铁矿质量比以及黄铁矿粒度对体系中砷的浸出率以及砷的氧化状态的影响。结果表明：砷的浸出率随黄铁矿与砷黄铁矿质量比的增加而升高,随黄铁矿粒度的增加而减少。当黄铁矿的粒度小于74μm、黄铁矿与砷黄铁矿质量比为10：2时,砷的最高浸出率为97.7%,比不添加黄铁矿时砷的浸出率提高了约43.18%。且黄铁矿可以加速As(Ⅲ)转化为As(Ⅴ),降低矿浆对细菌的毒害,使生物浸出体系细菌密度提高、pH下降、氧化还原电位φh升高并与砷黄铁矿形成原电池效应,从而促进砷黄铁矿的浸出。     

氧化亚铁硫杆菌（SH—T）氧化毒砂的机理

采用优良的氧化亚铁硫杆菌SH-T菌株对含金毒砂势光片和纯毒砂粉末进行氧化试验,并作了定量定域的显微观察分析,研究了每一阶段毒砂表面的性质和毒砂氧化膜的形成过程,毒砂在细菌氧化后覆盖了黄色氧化膜,抑制了细菌的快速氧化。用X射线粉晶衍射法对细菌氧化产物进行物相分析,结果表明氧化物的主要成分为黄钾铁矾,其次为砷华,细菌氧化膜的X射线光电子谱分析表明毒砂晶体中As表现出[AsS]^2→As(Ⅲ）→As(Ⅴ）的价态变化过程,揭示了细菌氧化过程中毒砂形貌变化规律和晶体的内在联系。     

Electrochemical oxidation of pyrrhotute in aqueous solution

The anodic surface oxidation of natural pyrrhotite in 0.3 mol/L KCI and HCI solution （pH 4.0） and 0.1 mol/L Na2B4O7 solution （pH 9.18） respectively was investigated by using cyclic voltammetry, Tafel plot, and chronoamperometry. In 0.3 mol/L KCl and HCl solution （pH 4.0）, at potential less than 0.5 V（vs SHE）, the production of anodic oxidation on pyrrhotite surface can not maintain a stable phase to form a passive film. In 0.1 mol/L Na2B4O7 solution （pH 9.18）, when the electrode potential increases to more than 0.5 V （vs SHE）, part of S is oxidized to sulfate, making the passive film somewhat porous, but elemental S and metal oxidates Fe（OH）3 still remain on the electrode surface, and the passive film can not be broken down totally. According to PARCalc Tafel analysis, the corresponding corrosion current density （J0） is 5.34 μA/cm^2 , which is also the exchange current density of the oxidation reaction on pyrrhotite electrode surface in 0. 1 mol/L Na2B4O7 solution （pH 9. 18）. The electrochemical dynamics equation of the oxidation was determined.     

高铁酸盐(Ⅵ)与毒砂表面的作用机理及其对黄铜矿与毒砂浮选分离的影响（英文）

通过浮选试验、接触角测量、吸附量测试、交流阻抗测试和XPS分析研究一种新型环保抑制剂高铁酸钾(K₂FeO₄)在乙基黄药捕收剂体系下对毒砂和黄铜矿的抑制作用。结果表明,在pH值为4～11的范围内,高铁酸钾强烈抑制毒砂,在pH 8或10时,采用5×10^-4 mol/L K₂FeO₄和5×10⁵ mol/L PEX可以实现黄铜矿与毒砂的浮选分离。在K₂FeO₄和PEX存在时,毒砂的接触角和黄药吸附量显著降低。LEIS测量表明,高铁酸盐的加入可以显著增加毒砂表面的阻抗。XPS分析进一步证实,高铁酸盐加速毒砂表面的氧化。     

Electrochemical oxidation of WC in acidic sulphate solution

The electrochemical oxidation of WC in aqueous solutions is critical for the functional stability of hardmetals in aggressive environments. The oxidation of WC and the nature of the oxides formed in 0.1 M sulphuric acid under electrochemical polarisation have been studied by electrochemical methods (cyclic voltammetry, chronoamperometry). The structure and composition of the electrochemically treated surfaces has been analysed by X-ray diffraction, surface Raman spectroscopy and energy dispersive analysis of characteristic X-rays. The morphology of the attacked surfaces was investigated by scanning electron microscopy. Anodic attack gives rise to hydrous WO₃ forming a continuous film which tends to develop pits. Alternated anodic and cathodic polarisation yields a very similar composition, but with a lower degree of hydration. The morphology is characterised by micrometric loose grains forming by disruption of the larger grains of the pristine sintered WC surface. The electrochemical conditions giving rise to the inception of WO₃ formation by WC oxidation could be accurately identified by monitoring the inception of the development of the cathodic loop corresponding to the electrochemical behaviour of the electrochromic material.     

Influence of mechanical activation on leaching kinetics of arsenopyrite

The influence of mechanical activation on the leaching kinetics of arsenopyrite was studied using a planetary centrifugal mill. It shows that mechanical activation can enhance the leaching process of arsenopyrite in a nitric-sulfate acidic solution. The leaching ratio within 20 min leaching time can increase from 2 % to 80 %～ 100 % ; 10 and 20 minties‘ activation can depress the apparent activation energy of leaching reaction from 54.5 kJ/mol to 39.0 kJ/mol and 34.0 kJ/mol, respectively. This means that the leaching reaction becomes little dependent on tempeerature, and arsenopyrite can change from refractory to flexible one; mechanical activation also increases the interplanar distance between crystal faces. The displacement of atoms from its equilibrium position indicates the increase in inner energy.