黄铁矿吸附-还原金络合物的实验研究进展

金的吸附成矿作用是表生和低温条件下的一种重要成矿机制。本文综述了黄铁矿吸附-还原金络合物的实验研究方法,探讨了黄铁矿吸附-还原不同金络合物的反应机制和影响因素。黄铁矿对Au-S络合物的吸附作用主要是黄铁矿与Au-S络合物之间的静电吸附以及表面络合,由于吸附的Au-S络合物的还原反应相当缓慢,随着周围环境的变化很容易发生解吸附作用;而黄铁矿对Au-Cl络合物的吸附作用实质上是黄铁矿表面金络合物迅速的还原反应,通过还原作用形成自然金而使得解吸附率极低。As掺杂形成的p型黄铁矿以及和n型黄铁矿构成p-n结是导致金络合物在黄铁矿表面发生电化学沉淀的驱动因素。目前有关金的吸附实验都是在温度小于90℃的表生条件下进行的,开展一定温度和压力条件下的吸附成矿实验,尤其是利用电化学方法原位研究高温高压下黄铁矿-金络合物溶液之间的界面反应以及原电池效应对金络合物还原作用的影响,是今后研究的重点。

Progress in Experimental Investigations on the Adsorption-reduction of Gold Complexes by Pyrite

Gold adsorption metallogenesis is an important metallogenic mechanism at supergene and low temperature conditions.We summarized the experimental investigation methods of gold adsorption-reduction by pyrite and discussed the gold reduction mechanism on pyrite surface in different gold complexes solutions.The adsorption of Au-S complexes on pyrite surface is mainly the processes of electrostatic adsorption and surface complexation.Because the reduction reaction rate of the adsorption of Au-S complexes on pyrite surface is quite low,desorption will occurs once the conditions are changed.However,the adsorbed Au-Cl complexes on pyrite surface are rapidly reduced,and natural gold particles are produced through it,therefore,a process of desorption hardly occurs.p-type pyrite doped by arsenic is apt to form p-n junctions with n-type pyrite,which is the driving factors to result in electrochemical precipitation of gold complexes on pyrite surface.Gold adsorption experiments are currently conducted at conditions of supergene with temperatures < 90℃.Therefore,in the future,we should carry out adsorption metallogenic experiments at higher temperature and pressure conditions,especially combining with in-situ electrochemical approaches to investigate the influence of interface reaction between pyrite and gold complexes and galvanic effect on gold complexes reduction.