Gold Occurrence in Sulfide Ore Deposit and Process Mineralogy

本文以萨尔切什梅斑岩铜矿为例，研究了硫化物矿床的成因。通过对SarCheshmeh矿床矿石的矿物学研究，发现SarCheshmeh矿床矿石中的矿物组合与典型斑岩铜矿存款中的矿物组合相似。铜含量> 0.25%和> 0.4%的样品，其深成金平均含量分别为58.2和64.4 ppb Au，表生金平均含量分别为70.7和71.5 ppb Au。根据金属比值，Sar Cheshmeh斑岩铜矿可被评价为“富钼、相对贫金型”。斑岩铜矿选矿厂选矿产品中的金分布表明，只有约44%的金作为铜精矿的副产品被常规回收，其余的损失到尾矿中。金的浮选回收率主要受其与铜矿物的缔合程度和黄铁矿的回收率控制。金在矿石和选矿产品中以“可见”、“不可见”和包裹态等不同的赋存状态存在，虽然在硫化矿物中也有固溶体和胶体金，但“可见”金是金的主要赋存形态。采用氧化亚铁硫杆菌对混合浮选精矿进行生物浸出，然后进行氰化。使用该工艺，从生物浸出1周和2周的精矿中分别获得约61%和70%的金回收率。结果表明，该方法的浸出率高于氰化浸出法。

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.