金在石英表面沉淀的实验研究

EXPERIMENTAL STUDY ABOUT GOLD DEPOSITION ON THE QUARTZ SURFACE

为了考察石英表面特征对金沉淀的影响,于20—200C使不同切向的石英晶体光片与含金氯化物溶液相互作用。反应后石英光片表面的SEM/EDAX、XPS和显微镜研究结果表明,所有实验中均发现金在石英表面沉淀。结合显露石英位错的浸蚀实验,发现沉淀的金晶体在石英表面的分布似受石英晶体中存在的线性缺陷控制。本文分析了本实验研究结果与前人工作的差异,讨论了金的沉淀机理和含金石英脉中金的不均匀分布。

In order to investigate the influences of the surface characteristics of quartz on gold deposition , polished sections of natural quartz single crystals (perpendicular to the c axis of the mineral or randomly oriented) reacted with acid Au-bearing chloride solutions (Au = 500× 10-6, HC1 or HCl + NaCl solution, total chlorides=0. 03 mol/L, pH=1, 5) at 20, 100, 150 and 200 ℃ and the saturation vapour pressure of the system. The SEM/EDAX, XPS and microscopic studies of the surface of quartz sections after reaction show that gold crystallized at the surface of the mineral in all experiments and that higher temperatures were favourable for the nucleation and growth of gold. Many triangular and hexagonal gold crystals were deposited on the surface of quartz in the 200 C run. Through these experiments combined by the etching experiments by saturated NH4HF2 solution for exposing the dislocation in quartz, it was found that the distribution of gold crystals on the quartz surface seemed to be controlled by linear defects in quartz crystals. The differences between the results of the present experimental study and those of the previous study. It is emphasized that the understanding of the mode of occurrence of gold in ore-forming solutions has major importance for understanding the gold deposition mechanism. Besides, the inhomoge-neous distribution of gold in gold-bearing quartz veins is discussed.