镍基催化体系硫代硫酸盐高效浸金基础研究

Among non-cyanide leaching of gold, thiosulfate leaching is widely recognized as the most promising, in which copper and ammonia are used conventionally for the catalysis of gold leaching. However, this catalytic system also causes the problems that thiosulfate consumption is too high. A preliminary study done by proposer indicated that thiosulfate consumption could be obviously reduced without the decrease of gold leaching percentage when the catalytic system of copper and ammonia was replaced by the system of nickel and ammonia, the system of nickel and citric acid or the system of nickel and pyrophosphoric acid. So, this project proposes the idea that the conventional catalytic system of copper and ammonia is substituted by a nickel base catalytic system for the purpose of high efficient extraction of gold by thiosulfate. At first, the effects of types of ligands(L) on the catalysis of thiosulfate leaching of gold by the nickel base system and their effect mechanisms together with structure-activity relationship between Ni(Ⅱ)-L complex ions and the catalysis of gold leaching will be studied, and an optimized catalytic system is obtained. Afterwards, the electrochemical mechanism of the catalysis of thiosulfate leaching of gold by this optimized system, the reaction mechanisms of gold leaching and thiosulfate decomposition together with the effect of lixivium mixed potential on these two reactions will be studied. In the end, the effects of associated minerals on gold leaching by thiosulfate and their effect mechanisms together with the impacts of additives on the removal of influences of detrimental associated minerals will be studied. The oxidation of thiosulfate by Cu(Ⅱ)-NH3 complex ions can be avoided through the substitution of the nickel base catalytic system in the place of conventional copper and ammonia system. This project will provide a theoretical foundation to solve the problem of high thiosulfate consumption, and thus the industrial application of thiosulfate leaching of gold will be promoted strongly.

硫代硫酸盐法被广泛认为是最有前途的非氰化浸金方法，但需引入铜、氨以催化浸出，这也导致硫代硫酸盐消耗过高。申请人在前期研究中发现，镍氨、镍柠檬酸、镍焦磷酸替代铜氨催化均可明显降低硫代硫酸盐消耗，且它们的浸金率与铜氨催化基本相当。因此，本项目提出采用镍基催化体系取代传统的铜氨体系以实现硫代硫酸盐高效浸金的思路。拟首先研究配体（L）种类对镍基体系催化硫代硫酸盐浸金的影响及其机理和Ni(Ⅱ)-L配离子与其催化浸金的构效关系，得到优选的镍基催化体系。然后研究该体系催化浸金的电化学机理和金浸出、硫代硫酸盐分解的反应历程及浸出液混合电位对这两种反应的影响。最后研究该优选体系下伴生矿物对硫代硫酸盐浸金的影响及其机理与添加剂对消除有害伴生矿物影响的作用。镍基催化体系取代传统的铜氨体系可避免铜氨配离子对硫代硫酸根的氧化，该项目将为解决硫代硫酸盐耗量大问题提供理论基础，推动硫代硫酸盐法浸金的工业应用。

黄金是国民经济发展的重要战略物资。氰化法目前在黄金提取工业中占主导地位。但氰化物剧毒严重威胁生态环境。因此，推动非氰浸金方法的工业应用迫在眉睫。在众多非氰化提金方法中，硫代硫酸盐法被公认最有前途。但经过长期研究发现，该法广泛工业应用存在一个主要障碍—浸出剂耗量大。耗量大的最主要原因是由于铜氨催化体系对硫代硫酸根的氧化。因此本项目拟采用镍基新催化体系对铜氨进行取代，以期解决硫代硫酸盐法广泛工业应用的瓶颈问题。.本项目较系统地研究了镍基催化体系的组效关系，得到优选的镍基催化体系。通过对镍氨、镍柠檬酸、镍焦磷酸、镍草酸、镍EDTA等镍基催化组合进行对比研究，发现镍氨催化浸金效果最好，且硫代硫酸盐消耗相对铜氨催化显著降低。基于热力学及电化学研究，提出镍氨催化机理：氨在阳极催化金的溶解，四氧化三镍在阴极催化氧气的还原。还发现金浸出和硫代硫酸盐分解的反应历程及矿浆混合电位的影响与传统铜氨催化基本一致。揭示了镍氨催化下硫代硫酸盐浸金的动力学规律。氨、镍离子、硫代硫酸盐的反应级数分别为0.37、0.21、0.28，金浸出反应的表观活化能为9.59 kJ/mol，受反应物和产物通过固体层的扩散控制。该固体层主要由硫代硫酸盐氧化产物所组成。针对我国典型含金物料—金精矿焙砂进行研究发现，镍氨催化的浸金率与传统铜氨催化相当，镍氨催化取代铜氨不仅可以显著降低硫代硫酸盐消耗，且还有利于浸出贵液中金的树脂吸附法回收。此外，还发现镍氨催化下伴生矿物对浸金的影响与铜氨催化相似，同样采用某些有机高分子添加剂如腐殖酸可有效消除伴生矿物的不利影响。.通过本项目的研究发现，镍氨催化体系取代传统的铜氨体系可有效避免Cu(Ⅱ)-氨配离子对硫代硫酸盐的氧化作用和Cu(Ⅰ)-硫代硫酸根配离子对浸出液中金回收的干扰。该项目的实施为解决硫代硫酸盐耗量大问题提供了坚实的理论基础。本项目的开展对推动硫代硫酸盐法提金的工业应用，和对提高我国黄金提取与清洁冶金的科技水平具有非常重要的意义。