Mineral phase and structure changes during roasting of fine-grained carbonaceous gold ores and their effects on gold leaching efficiency  

作　　者：Jianping Jin Yuexin Han Hui Li Yangyang Huai Yongjun Peng Xiaotian Gu Wei Yang 

机构地区：[1]School of Resources & Civil Engineering,Northeastern University,Shenyang 110819,China [2]Xi'an Northwest Geological Institute Company of Nonferrous Metals Co.,Ltd.,Xi'an 710054,China [3]College of Material and Resource,Xi'an University of Architecture and Technology,Xi'an 710055,China [4]School of Chemical Engineering,The University of Queensland,St. Lucia,Brisbane 4072,Australia

出　　处：《Chinese Journal of Chemical Engineering》2019年第5期1184-1190,共7页中国化学工程学报（英文版）

基　　金：Supported by the National Natural Science Foundation of China(51704059,51474169)

摘　　要：While roasting has been widely applied to reduce the negative effect of carbonaceous matters on gold extraction from fine-grained carbonaceous gold ores, the phase and structure changes of minerals during roasting and their in fluences on the leachi ng rate of gold have not been fully understood. This limits the extraction of carbonaceous gold deposits. The current work examines the oxidation process of a fine-grained carbonaceous gold ore during roasting using a range of techniques including X-ray diffraction (XRD), seanning electron microscopy (SEM), Energy Dispersive Spectrometer (EDS) analysis and pore structure analysis together with gold leaching tests. The results show that during the process of oxidative roasting, the carbonaceous matters (organic carbon and graphitic carbon) and pyrite were completely decomposed at 600 ℃ with the carbonaceous components burned and pyrite oxidized into hematite. At 650 ℃, while dolomite was decomposed into calcia, magnesia, calcium sulfate etc., the calcine structure became loose and porous, leading to a high gold leaching rate from the roasted product. Above 750 ℃, the porous calcite structure started to collapse along with the agglomeration, leading to the secondary encapsulation of gold particles, which contributed to the sharp drop in the gold leaching rate of the roasted product. This study suggests optimum phase and structure changes of minerals during roasting to achieve maximum gold extraction from fine-grained carbonaceous gold deposits.While roasting has been widely applied to reduce the negative effect of carbonaceous matters on gold extraction from fine-grained carbonaceous gold ores, the phase and structure changes of minerals during roasting and their influences on the leaching rate of gold have not been fully understood. This limits the extraction of carbonaceous gold deposits. The current work examines the oxidation process of a fine-grained carbonaceous gold ore during roasting using a range of techniques including X-ray diffraction(XRD), scanning electron microscopy(SEM),Energy Dispersive Spectrometer(EDS) analysis and pore structure analysis together with gold leaching tests.The results show that during the process of oxidative roasting, the carbonaceous matters(organic carbon and graphitic carbon) and pyrite were completely decomposed at 600 ℃ with the carbonaceous components burned and pyrite oxidized into hematite. At 650 ℃, while dolomite was decomposed into calcia, magnesia, calcium sulfate etc., the calcine structure became loose and porous, leading to a high gold leaching rate from the roasted product. Above 750 ℃, the porous calcite structure started to collapse along with the agglomeration, leading to the secondary encapsulation of gold particles, which contributed to the sharp drop in the gold leaching rate of the roasted product. This study suggests optimum phase and structure changes of minerals during roasting to achieve maximum gold extraction from fine-grained carbonaceous gold deposits.

关 键 词：CARBONACEOUS gold ORE ROASTING LEACHING X-ray DIFFRACTION (XRD) Scanning electron microscopy (SEM) 

分 类 号：TQ[化学工程]