矿物吸附金的实验研究及其在红土型金矿形成中的意义  

Experimental Study of Gold Adsorption by Minerals and Its Signification in Forming of Lateritic Gold Deposits

作　　者：王燕[1] 谭凯旋[1] 刘顺生[1] 陈梦熊[2] 

机构地区：[1]中国科学院长沙大地构造研究所 [2]有色金属矿产地质调查中心,北京100814

出　　处：《地球科学（中国地质大学学报）》2003年第1期26-30,共5页Earth Science-Journal of China University of Geosciences

基　　金：国家自然科学基金项目 (No .70 1710 5 7) ;中国科学院知识创新工程重要方向项目 (No .KZCX2 -10 1)

摘　　要：Au(Ⅲ ) -氯化物和Au(Ⅰ ) -硫代硫酸盐被蒙脱石、高岭石、伊利石、针铁矿、褐铁矿及黄铁矿的吸附实验研究结果表明 ,各种矿物对AuCl-4的吸附作用显著大于Au(S2 O3 ) 3 -2 ,粘土矿物对金的吸附能力 ,蒙脱石 >高岭石 >伊利石 ;含铁矿物中 ,黄铁矿 >针铁矿 >褐铁矿 .矿物对金的吸附作用与矿物结构和金的存在形式有关 ,即受矿物表面基、金组分的稳定性和位阻的影响 ;天然雨水中所含微量H2 O2 是Au、黄铁矿等不同矿物氧化 -还原的催化剂 ,可加速地表岩 (矿 )石的风化氧化过程和Au的溶解与迁移 .雨水对红土中的Au具有一定的淋滤浸取能力 .红土型金矿形成于富Cl-、SO2 -4的酸性、氧化的水化学环境 ,含金黄铁矿等硫化物的氧化不仅直接导致了Au的溶解和酸的释放 ,而且其反应产物Fe3 + 、S2 O2 -3 等为Au的氧化、溶解和迁移提供了氧化剂和络合剂 ,并促进Au的溶解和迁移 ;Au主要以硫代硫酸络合物、氯化络合物及其水合物的形式进行迁移 ;硫代硫酸根的氧化和风化壳下部的还原作用是导致金络合物失稳、Au被其他矿物吸附和沉淀富集的主要因素 .Gold (Ⅲ) chloride and gold (Ⅰ) thiosulfate adsorption by various minerals and ores were experimented and studied in the paper. The adsorption of AuCl - 4 by minerals is much higher than Au (S 2O 3) 3- 2. The adsorption is montmorillonite>kaolinite>illite for clay minerals, and pyrite>goethite>limonite for iron bearing minerals. H 2O 2 containing in meteoric water is a catalyst for oxidation or reduction of gold, pyrite and other minerals, so that it can speed up weathering process and Au dissolution and migration under supergene conditions. The meteoric water can, to some extent, leach gold in laterite, and the leaching capacity is controlled by compositions of the leached rocks and minerals. Meteoric water, KCl, oxalic acid, citric acid, hypo and other solutions are also able to leach some gold in laterite, but their leaching capacities are quite different from one another even for same sample. The lateritic gold deposits were produced under the acidic, oxidizing and Cl -, SO 2- 4 rich hydro geochemical environment. Gold migrated as sulpho sulphate complex, chloride complex and their hydrates and the key factors were the oxidation of sulpho sulphate complex anions and the subsequent reduction in the lower part of the weathering crusts to make Au bearing complexes unstable and then to make the released gold concentrated, precipitated or absorbed by other minerals. The adsorption of gold by minerals plays an important role during minerogenetic process of lateritic gold deposits.

关 键 词：矿物表面吸附作用 红土型金矿床 成矿作用 风化壳 存在形式 

分 类 号：P618.51[天文地球—矿床学]