Gold Occurrence in Sulfide Ore Deposit and Process Mineralogy

以Sar Cheshmeh斑岩铜矿为例进行了硫化物矿床研究。本研究除了对露头矿和钻孔岩心采集的矿样进行检验外，还对加工矿样进行了检验。样品的矿物学特征表明，SarCheshmeh矿床矿石中的矿物组合与典型斑岩铜矿相似。含铜量为> 0.25%和> 0.4%的下第三系矿石平均金含量分别为58.2和64.4 ppb Au，含铜量为> 0.4%的上第三系矿石平均金含量分别为70.7和71.5 ppb Au。根据金属比，可将沙舍梅斑岩铜矿评价为“富钼、相对贫金型”。该斑岩铜矿选矿厂选矿产品中的金分布表明，铜精矿中常规回收的副产物金仅占44%左右，其余均以尾矿形式流失。浮选回路中金的回收率主要受其与铜矿物的结合程度和黄铁矿的回收率控制。金以“可见”、“不可见”和包封形式存在于矿石和选矿产品中，虽然在硫化矿物中存在一些固溶体和（或）胶体大小的金，但“可见”金是金的主要形式。在此基础上，对该厂尾矿中的金进行了大规模硫化浮选试验。采用氧化亚铁硫杆菌对浮选精矿进行生物浸出，并进行氰化处理。采用该工艺，浸出1周和2周的金回收率分别为61%和70%。结果表明，氰化浸出法的回收率高于其他浸出法。

The Sar Cheshmeh porphyry copper ores were studied as a case study for the sulfide ore deposits. Processed ore samples in addition to collected ore samples from outcrop and drilling core were examined in this study.The mineralogy of the samples suggests that the mineral assemblages in ores of SarCheshmeh depositare alike to those in the typical porphyry copper deposit. The average gold contents of the samples rontaining >0.25 % and >0.4 % Cu in the hypogene were determined as 58.2 and 64.4 ppb Au and in the supergene ores were 70.7 and 71.5 ppb Au, respectively. Based on the metal ratios the Sar Cheshmeh porphyry copper ore can be evaluated as "Mo-rich, relatively Au-poor type".The gold distribution in the mill products of the porphyry copper beneficiation plant demonstrates that only about 44 % of the gold is routinely recovered as the byproduct in the copper concentrate, and the remaining is lost to the tailings. The recovery of gold in the flotation circuit was controlled mainly by its degree of association with copper minerals and the recovery of pyrite. Gold was present in the ore and mill products in different modes of occurrence including "visible" ,"invisible" and encapsulated forms Though there was some gold in solid solution and/or colloidal size within the sulfide minerals, "visible" gold was the principal form of the gold.Based on these results, attempts were made to scavenge gold from the plant tailings by bulk sulfide flotation. Then bio-leaching of the bulk flotation concentrate with Thiobacillus ferrooxidans was conducted, followed by cyanidation. Using this process, about 61 % and 70% of gold recovery were obtained from the concentrates bio-leached for 1 and 2 weeks, respectively. The recovery was found to be higher than that by another leaching methods with cyanidation.