脆硫锑铅矿在乙硫氮-饱和Ca(OH)2体系中的电化学

采用循环伏安和交流阻抗法研究了脆硫锑铅矿在乙硫氮-饱和Ca(OH)2体系中的电化学,讨论了电位调控浮选脆硫锑铅矿的工艺参数.电位在-378～22mV范围内,矿物的界面电容不断减少,介电常数变小,表面产物是疏水性的(CH3)2NCSS-、Pb((CHs)2NCSS-)2和S0;电位在22～222 mV范围内时,矿物表面的疏水产物膜迅速破裂,电容增加,介电常数变大,界面亲水性增强.随着电位的继续升高,矿物表面不断产生亲水性离子和Fe(OH)3的沉积;对于乙硫氮-饱和Ca(OH)2水溶液体系,脆硫锑铅矿的电位调节浮选的工艺参数应控制在-178～122 mV之间,实际工艺中电位控制在-78 mV～50 mV范围为宜.     

酸性溶液中不同电位下脆硫锑铅矿/DDTC界面的电化学机制

用循环伏安和交流阻抗法,研究了脆硫锑铅矿在含乙硫氮的pH 4.0缓冲溶液中的表面电化学行为,讨论了在不同电位下脆硫锑铅矿表面的反应、电化学吸附、钝化作用、电化学阻抗、微分电容的变化.结果表明:在酸性溶液中,脆硫锑铅矿具有盐的特性;电极过程呈现出受电化学反应及产物吸附控制的动力学特征.当电极电位为-78 mV～422 mV,矿物表面疏水性膜逐渐增长并产生钝化作用;当电极电位为522 mV时,电极过程完全由离子扩散决定的电化学反应所控制;当电位大于622 mV后,电极反应产生大量的PbSO4沉淀,并覆盖在电极表面,矿物表面的亲水性强.     

方铅矿与脆硫锑铅矿在高碱体系中的浮选电化学行为（英文）

为有效分离方铅矿和脆硫锑铅矿并提高其在混合浮选中的回收率,研究两者与乙硫氮捕收剂(DDTC)的作用机理。通过单矿物浮选实验研究矿浆p H值对两者浮选行为的影响。通过循环伏安法和塔菲尔曲线测试研究两者与乙硫氮作用的电化学性质。浮选实验结果表明,在高碱体系中脆硫锑铅矿被石灰强烈抑制。循环伏安曲线和塔菲尔曲线表明,乙硫氮与方铅矿和脆硫锑铅矿的作用是电化学过程。高碱体系对方铅矿与乙硫氮的作用影响不大,但是对脆硫锑铅矿影响很大,这是其自身氧化以及OH-和Ca OH+等离子的特性吸附,导致非电活性的羟基化合物和低导电性的钙系化合物附着在其表面,阻碍电子在电极表面的传递,从而使脆硫锑铅矿的可浮性降低。     

乙硫氮在铁闪锌矿表面吸附的电化学行为及机理

采用光谱分析、循环伏安及恒电位阶跃法,研究了乙硫氮(NaD)在铁闪锌矿表面吸附的电化学行为及机理,该机理与浮选电化学的混合电位模型并不一致.在酸性条件下,当电位为0～200 mV时,乙硫氮在铁闪锌矿表面电化学吸附形成双乙硫氮(D2);当电位为410 mV时,乙硫氮与矿物发生电化学反应形成ZnD2和S°,并产生钝化,且表面疏水性强;当电位大于600 mV,电极过程由自腐蚀反应控制.在中性和碱性条件下,铁闪锌矿表面的电极过程主要由自腐蚀阳极溶解控制.随着pH值的增大,表面中间态分别为Fe(OH)D2、Fe(OH)2D和Zn(OH)D,并随电位增大进一步氧化成Zn(OH)2、Fe(OH)3和D2,且矿物表面亲水性强.在开路电位条件下,铁闪锌矿表面存在双乙硫氮和乙硫氮金属盐,但不能有效地附着在电极表面.     

脆硫锑铅矿与捕收剂作用的界面电化学

采用线性极化、交流阻抗法,研究了脆硫锑铅矿在自然pH介质中,有无二乙基二硫代氨基甲酸钠(DDTC)存在时的界面电化学行为.结果表明:随着DDTC浓度增加,φcorr负移,Icorr减少,抑制了阴极反应,促进了阳极反应;有DDTC比无DDTC存在时的电阻增大了4倍,双电层电容减少,且随着DDTC浓度的增加,电化学电阻稍为减少而双电层电容增大;DDTC在脆硫锑铅矿表面呈扁平状化学吸附,并伴随DDTC-金属离子的盐沉积,产生钝化作用,氧化反应受阻;脆硫锑铅矿在无DDTC存在时,因存在明显的硫钝化膜,可实现无捕收剂浮选,可浮电位范围为:0.173～0.373V;有DDTC时,主要表现出因DDTC的化学吸附、DDTC-金属离子盐沉积而浮选,也存在疏水性硫对浮选的影响,可浮电位范围为:0.100～0.473V.     

复杂矿物脆硫锑铅矿的电子结构与浮选行为（英文）

采用密度泛函理论研究复杂矿物脆硫锑铅矿的电子结构及其浮选行为。脆硫锑铅矿的浮选行为与辉锑矿相似,p H值小于6时具有较好的可浮性,并且容易被NaOH抑制,尤其是在有石灰存在时。在弱碱性条件下,脆硫锑铅矿的浮选行为接近于方铅矿的浮选行为。脆硫锑铅矿中Pb的配位结构比方铅矿中Pb的配位结构复杂。脆硫锑铅矿中的Sb存在2种配位模式,而辉锑矿中的Sb仅存在3-配位。方铅矿中的Pb比脆硫锑铅矿中的Pb活跃。与辉锑矿中的Sb相比,脆硫锑铅矿中的Sb(3-配位)不活跃,但是4-配位的Sb比3-配位的Sb活跃得多。脆硫锑铅矿和辉锑矿的HOMO轨道含有金属原子,石灰的存在有助于CaOH+吸附构型的形成。因此石灰对脆硫锑铅矿和辉锑矿都具有抑制作用。     

巯基类小分子有机抑制剂对复杂硫化矿物浮选行为的抑制机理

通过浮选实验、红外光谱测定,考察了脆硫锑铅矿、磁黄铁矿和铁闪锌矿在丁黄药作用下的浮选行为和巯基类小分子有机抑制剂(巯基乙酸、巯基乙醇)对三种矿物的抑制效果以及Cu2 离子对巯基化合物抑制效果的影响。结果表明:用丁黄药作捕收剂,脆硫锑铅矿和磁黄铁矿在pH 2~10范围内都有良好的可浮性,铁闪锌矿在酸性条件下可浮性好,三者分离困难;在pH 6~8之间,采用巯基乙酸和巯基乙醇作抑制剂,脆硫锑铅矿与磁黄铁矿和铁闪锌矿的分离是可能的;但铜离子存在时,3种矿物之间的选择性分离是难以实现的。红外光谱测试表明:在抑制剂分子中有多种官能团如—SH、—COOH、—OH等。丁黄药和抑制剂在矿物表面存在竞争吸附,有机抑制剂携带亲水基团,使得矿物表面更容易亲水,从而受到抑制。     

无捕收剂浮选时硫化矿物表面的疏水—亲水平衡关系

通过硫化矿物表面中性硫(S~o)的溶剂提取-化学分析、矿浆电位测定和浮选试验,建立了自诱导浮选和硫化钠诱导浮选的疏水-亲水平衡关系,分别用[S~o]/[OH~-]和[S~o]/[OH~-]+[HS~-])表示S~o的生成量[S~o]受矿浆电位调控研究结果表明,pH值相同时,[S~o]值越大,矿物表面疏水性高,浮选行为好pH值高,[OH~-]值高,矿物表面亲水性大,浮选需要的[S~o]多;反之亦然同一pH值下,硫化钠诱导浮选所需[S~o]较自诱导浮选高     

铁闪锌矿的腐蚀电化学研究

采用Tafel曲线、交流阻抗法，研究了铁闪锌矿与浮选药剂相互作用的界面电化学行为．结果表明：pH对铁闪锌矿的腐蚀电位几乎无影响，但随着pH增大，腐蚀电流增大，矿物表面的疏水性元素S^0急剧减少，羟基化作用变大；二乙基二硫代氨基甲酸钠是铁闪锌矿的腐蚀剂和浮选抑制剂，Ca(OH)2在成本和性能上，都是碱性浮选介质中最佳的pH调整剂．     

银含量对方铅矿浮选行为的影响及捕收机理研究

以含银方铅矿为研究对象,考查了丁铵黑药、乙基黄药、乙硫氮三种捕收剂,碳酸钠、石灰两种调整剂对其浮选行为的影响,并通过Zeta电位测定和吸附量测定进行捕收机理分析。浮选行为结果表明：含银方铅矿适合在弱碱性介质下回收,且含银量越高,上浮趋势越明显;与石灰相比,碳酸钠做调整剂时获得的含银方铅矿回收率更高;丁铵黑药是弱碱性介质下回收含银方铅矿较好的捕收剂,乙硫氮在强碱性介质中也可以回收含银方铅矿,但回收率偏低。机理分析结果表明：在弱碱性介质下,丁铵黑药不仅表面Zeta电位负移量明显高于其他两种药剂,而且在含银方铅矿表面的饱和吸附量也最大。根据热力学方法计算得到丁铵黑药和乙硫氮浮选含银方铅矿的临界pH值分别为9.27和10.81,与实际浮选规律一致。     

Corrosive electrochemistry of jamesonite

The corrosive electrochemistry of jamesonite (Pb4FeSb6S14 ) was studied by the electrochemical methods of cyclic voltammetry, polarization, and AC impedance. The electrochemical processes of jamesonite were controlled by the corrosive reactions, growth of the metal-deficient and sulfur-riched layer, passivation and breakdown of elemental sulfur film on the electrode surface. The corrosive potential(φcorr) moves negatively, its corrosive current increases, and hydroxyl action becomes stronger with the rising pH value. The charge transfer resistance increases and the capacitance decreases due to the gradual growth of the metal-deficient and sulfur-riched layer on the mineral surface from -378 to 122mV (vs SHE). Element sulfur layer is formed at the potential of 122 mV. The charge transfer resistance increases and its capacitance rises slowly due to the gradual breakdown of sulfur film at voltage from 222mV to 422mV. S2O3^2- and SO4^2- ions occur when the electrode potential is over 422 mV. Under basic condition, the hydrophobic hydroxyl precipitate occurs on jamesonite surface, so that its collectorless floatability is poor. Under the condition of pH6.86, it can be deduced that the potential range of collectorless floatability of jamesonite is from 22 to 422mV due to the passive action of the hydrophilic sulfur on jamesonite surface, and its optimum range of floatable potential is between 122 and 322mV.     

FTIR spectroscopic study of electrochemical flotation of jamesonite-diethyldithiocarbamate system

1 Introduction Flotation electrochemistry and modern surface analytical techniques have enhanced our understanding of reagent-mineral interaction mechanism. Great progress has been made by applying various electrochemical techniques to investigate the int…     

双氧水水热处理泡沫镍制备 Ni(OH) 2 自集流超级电容器电极材料

目的寻找一种简便、价廉、对环境友好的方法制备具有高比容、长寿命的Ni(OH)2自集流超级电容器电极材料。方法采用水热法(15%(质量分数)的H2O2溶液,180℃,24 h)直接在泡沫镍集流体上原位生长Ni(OH)2,并对其形貌、组成以及电化学性能进行研究。结果通过双氧水水热处理,可以在泡沫镍集流体上原位生长出边长400~600nm、厚度约200nm的Ni(OH)2六边形片,此为六方晶的β-Ni(OH)2。该电极材料在2mol/LKOH溶液中的最高比容为2534F/g(扫速1mV/s),且循环1000圈后,比容值仍保持在91%以上(扫速为50mV/s)。结论该制备方法简单价廉,对环境友好,制得的电极材料具有自支撑、自集流的特点,且具有优异的电化学性能和良好的循环稳定性。     

阳极极化状态下铁电极的交流阻抗

研究了铁电极在中性Na_2SO_4溶液中恒电位阳极极化下。和在不同pH的H_2SO_4/Na_2SO_4溶液中腐蚀电位下的交流阻抗特性。当pH>3.5时,铁电极的界面电容急剧增大至10~3μF/cm~2数量级。而铁电极在中性Na_2SO_4溶液中的界面电容为铁电极上覆盖的Fe(OH)2的电容。通过恒电位阳极极化状态铁电极的高频和低频部份的阻抗特性分析,建立了阳极极化状态铁电极的等效电路。用交流阻抗计算了极化电流密度,其值与同样条件下测得的稳态电流密度相等,说明阳极极化状态下交流阻抗测定的适用性。     

高强度预应力钢丝在饱和Ca(OH)_2+NaCl环境中的应力腐蚀开裂

用慢应变速率拉伸和悬臂樑试验法研究了国产高强度预应力钢丝在饱和Ca(OH)_2+NaCl溶液中的应力腐蚀行为。结果表明,钢丝在含有氯离子的Ca(OH)_2溶液中会产生应力腐蚀开裂,其开裂敏感性随溶液中NaCl含量的升高和溶液pH值的降低而增大。Ca(OH)_2溶液中有Na_2SO_4存在也对钢丝的应力腐蚀带来不良影响。向Ca(OH)_2+NaCl溶液中添加NaNO_2可以抑制离氯子对钢丝应力腐蚀的有害作用。结合闭塞电池模拟试验中溶液pH值的变化以及极化电位和加载载荷谱对开裂敏感性的影响等试验结果,讨论了钢丝在Ca(OH)_2+NaCl溶液中应力腐蚀开裂的机理和应变率的作用。     

Untersuchungen zum Einfluß von Sulfid- und Sulfationen auf die Korrosion des Eisens in alkalischer Lösung

Investigation into the influence of sulfide and sulfate ions on the corrosion of iron in alcaline solution The corrosion behaviour of Armco iron as well as that of a technical high-strength steel was investigated in sulphide - and sulphate-containing electrolytes of pH ～ 12.6. Current density - potential curves show that iron, after successful passivation, remains passive and protected against corrosion in a solution saturated with CaS, CaSO₄ and Ca(OH)₂ at potentials up to 800 mV(EH). Passivation experiments conducted by changing from the active region to various anodic potentials yielded a critical potential region around 300 mV(EH), above which corrosion appeared. Up to E_H = 200 mV complete passivation was observed. The same critical potential region was observed in experiments of repassivation after mechanical damaging of a protective passive layer. Additional tensile stresses of 85%· σ_0,2 caused no stress corrosion cracking at a potential of 500 mV(EH). After damaging the passive layer, through scratching of the stressed wires fracture occured at and above potentials of 300 mV(EH). At 200 mV(EH) repassivation was observed even under tensile load. In a sulphate-free Na₂S/Ca(OH)₂ solution of the same sulphide ion concentration no stress corrosion cracking of the samples occured at any potential up to 800 mV(EH) even after scratching the steel samples. The observed stress corrosion in sulphide - and sulphate-containing electrolytes is to be ascribed to the action of sulphate and not to sulphide ions.     

Selective depression of copper-activated sphalerite by polyaspartic acid during chalcopyrite flotation

Environmentally friendly flotation reagent, polyaspartic acid (PAPA), was tested as a potential selective depressant in the flotation separation of chalcopyrite and Cu-activated sphalerite. The depression mechanism of PAPA was revealed by contact angle measurements, Zeta potential measurements, Fourier transform infrared spectroscopy (FT-IR) analysis and inductively coupled plasma (ICP) measurement. The micro-flotation tests with single minerals showed that PAPA selectively depressed Cu-activated sphalerite, while chalcopyrite remained floatable. Moreover, a concentrate containing 31.40% Cu with a recovery of 92.43% was obtained in flotation tests of artificially mixed minerals. Results of contact angle measurements, Zeta potential measurements and FT-IR spectrum revealed that PAPA exerted a much stronger adsorption on Cu-activated sphalerite surface than on chalcopyrite surface, preventing the further adsorption of sodium diethyl dithiocarbamate (DDTC) on its surface. ICP measurements indicated that PAPA had an excellent complexing ability with Cu²⁺ in flotation pulp, weakening the activation of Cu species on sphalerite surface and producing selective depression.     

45MnSiV预应力钢筋的应力腐蚀

用慢应变速率、动电位扫描和断口分析等试验方法,研究了45MnSiV 预应力高强度钢筋的应力腐蚀行为。结果表明,在未受侵蚀的混凝土中.45MnSiV 预应力钢筋不会发生应力腐蚀开裂;若 HCl,NaCl 或 SO_2等侵入混凝土,使其 pH 值下降,则会出现阳极溶解型的应力腐蚀。45MnSiV 预应力钢筋的最佳阴极保护电位为-800mV(SCE)左右。如果外加电位偏低,则不论混凝土受侵蚀与否,均将引起45MnSiV 预应力钢筋的氢致开裂。