胺性硫代硫酸盐浸金电化学机理研究

发布时间：2018-03-17 16:18

本文选题：硫代硫酸盐　切入点：浸金　出处：《昆明理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：硫代硫酸盐作为一种能替代氰化物的最有应用前景的无毒浸金试剂被广泛关注。但是,多数研究者采用的铜氨硫代硫酸盐浸金体系存在试剂耗量大且氨对环境有污染等缺点。用多胺来代替氨水,可以保持硫代硫酸盐浸金效率的同时大幅降低硫代硫酸盐的消耗量,但体系中铜络离子、游离铜离子对金的溶出过程的影响尚不清楚。本文采用电化学中的塔费尔(Tafel)曲线研究硫代硫酸盐浸金体系中铜离子浓度、硫代硫酸盐浓度和不同配体对金腐蚀电流密度、腐蚀电位、腐蚀电阻的影响；采用线性伏安扫描(LSV)曲线研究浸金体系中铜离子浓度、硫代硫酸盐浓度对峰电位和峰电流的影响,从而得出上述单因素对金溶解性能的影响。采用电化学阻抗谱(EIS)曲线来研究胺(氨)硫代硫酸盐浸金体系中铜离子浓度、硫代硫酸盐浓度和不同配体对极化电阻及其动力学行为影响,进而推测铜离子及其络合物对金溶出过程的影响。Tafel和LSV研究表明：分别以氨、乙二胺为配体时,随着铜离子浓度的增加,金腐蚀电位降低,极化电阻减小；金腐蚀电流密度和峰电位增大,峰电流增加,这说明铜离子能加快金的溶蚀速率。在铜离子浓度为0.0002mol/L～0.0008mol/L时,反应级数为1。但硫代硫酸盐对金溶出的电化学过程影响较为复杂。两种浸金体系对比发现,乙二胺浸金体系比氨浸金体系使金更易于溶蚀,且溶蚀速率更快。EIS研究表明,在铜氨浸金体系,当铜离子浓度为0～0.0008mol/L时,控制浸金反应速率的步骤主要为电荷转移控制,当铜离子浓度介于0.0008mol/L～0.002mol/L时,控制反应速率的步骤主要为电荷转移控制和扩散控制同时进行,当铜离子浓度介于0.002mol/L～0.008mol/L时,控制反应速率的步骤主要为扩散控制；对铜乙二胺浸金体系中的当铜离子浓度介于0.0001 mol/L～0.006mol/L时,控制浸金反应速率的步骤主要为电荷转移控制；当铜离子浓度介于0.006mol/L～0.0008mol/L时,控制反应速率的步骤主要为电荷转移控制和扩散控制同时进行。结合浸金体系中铜(Ⅱ)分布状态和金溶出的控制步骤分析表明,在一定范围内溶液中游离铜离子与金之间的电子交换速率对金的氧化溶出起主要作用。
[Abstract]:Thiosulfate, as one of the most promising non-toxic gold leaching reagents that can replace cyanide, has attracted wide attention. The copper thiosulfate leaching system used by most researchers has many disadvantages, such as high reagent consumption and ammonia pollution to the environment. Using polyamines instead of ammonia water can keep the efficiency of gold leaching by thiosulfate and reduce the consumption of thiosulfate significantly. However, the effect of copper complex ion and free copper ion on the dissolution process of gold is not clear. The concentration of copper ion in thiosulfate leaching system is studied by using the Tafel curve of electrochemistry. The effects of thiosulfate concentration and different ligands on the corrosion current density, corrosion potential and corrosion resistance of gold were studied by using linear voltammetry scanning spectroscopy (LSVV) curve to study the effects of copper ion concentration and thiosulfate concentration on peak potential and peak current in gold leaching system. The influence of the single factor on the dissolution of gold was obtained. The concentration of copper ion in the gold leaching system was studied by using the electrochemical impedance spectroscopy (EIS) curve, and the electrochemical impedance spectroscopy (EIS) curve was used to study the concentration of copper ion in the gold leaching system. The effects of thiosulfate concentration and different ligands on polarization resistance and kinetic behavior were deduced. Tafel and LSV studies showed that when ammonia and ethylenediamine were used as ligands, the effects of copper ions and their complexes on the dissolution process of gold were deduced. With the increase of copper ion concentration, the corrosion potential of gold decreases, the polarization resistance decreases, the current density and peak potential of gold increase, and the peak current increases, which indicates that copper ion can accelerate the dissolution rate of gold. When the concentration of copper ion is 0.0002mol / L, 0.0008 mol / L, The order of reaction is 1. However, the influence of thiosulfate on the electrochemical process of gold dissolution is more complicated. The comparison between the two gold leaching systems shows that the gold leaching system of ethylenediamine is easier to dissolve than the gold leaching system of ammonia, and the dissolution rate is faster. In the copper ammonia gold leaching system, when the concentration of copper ion is 0.0008 mol / L, the main step to control the gold leaching rate is charge transfer control, and when the copper ion concentration is 0.0008 mol / L, 0.002 mol / L, The steps of controlling the reaction rate are charge transfer control and diffusion control. When the concentration of copper ion is 0.002 mol / L ~ 0.008 mol / L, the main step of controlling the reaction rate is diffusion control. When copper ion concentration is 0. 0001 mol/L~0.006mol/L, charge transfer control is the main step to control gold leaching rate in copper ethylenediamine gold leaching system, and when copper ion concentration is 0. 006 mol / L ~ 0. 0008 mol / L, The main steps to control the reaction rate are charge transfer control and diffusion control. The electron exchange rate between free copper ion and gold in a certain range plays an important role in the oxidation dissolution of gold.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TD953

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