Kazemi Mohammad Javad, Kargar Mohammad, Nowroozi Jamileh, Akhavan Sepahi Abbas, Doosti Abbas, Manafi Zahra
Department of Microbiology, Tehran North Branch, Islamic Azad University, Tehran, Iran.
Department of Microbiology, Jahrom Branch, Islamic Azad University, Jahrom, Iran.
Rev Argent Microbiol. 2019 Jan-Mar;51(1):56-65. doi: 10.1016/j.ram.2017.09.004. Epub 2018 Jun 25.
Thermoacidophiles can exist in a state of dormancy both in moderate temperatures and even in cold conditions in heap leaching. Sulphide mineral ores such as chalcopyrite produce sulfuric acid when exposed to the air and water. The produced sulfuric acid leads to the decrease of pH and exothermic reactions in heap leaching causing the temperature to increase up to 55°C and the activation of thermoacidophilic microorganisms. The aim of the present study was to isolate indigenous extreme thermoacidophilic microorganisms at ambient temperature from Sarcheshmeh Copper Complex, to adapt them to the high pulp density of a chalcopyrite concentrate, and to determine their efficiency in chalcopyrite bioleaching in order to recover copper. In this study samples were collected at ambient temperature from Sarcheshmeh Copper Complex in Iran. Mixed samples were inoculated into the culture medium for enrichment of the microorganisms. Pure cultures from these enrichments were obtained by subculture of liquid culture to solid media. Morphological observation was performed under the scanning electron microscope. Isolates were adapted to 30% (w/v) pulp density. For the bioleaching test, the experiments were designed with DX7 software. Bioleaching experiments were carried out in Erlenmeyer flasks and a stirred tank reactor. The highest copper recovery in Erlenmeyer flasks was 39.46% with pulp 15%, inoculums 20%, size particle 90μm and 160rpm. The lowest recovery was 3.81% with pulp 20%, inoculums 20%, size particle 40μm and 140rpm after 28 days. In the reactor, copper recovery was 32.38%. Bioleaching residues were analyzed by the X-ray diffraction (XRD) method. The results showed no jarosite (KFe(SO)(OH)) had formed in the bioleaching experiments. It seems that the antagonistic reactions among various species and a great number of planktonic cells in Erlenmeyer flasks and the stirred tank reactor are the reasons for the low recovery of copper in our study.
嗜热嗜酸菌在堆浸过程中，不仅能在中等温度下，甚至在寒冷条件下以休眠状态存在。诸如黄铜矿之类的硫化矿物矿石在暴露于空气和水时会产生硫酸。所产生的硫酸导致堆浸过程中pH值降低和放热反应，使温度升高至55°C，并激活嗜热嗜酸微生物。本研究的目的是在常温下从萨尔切什梅铜矿综合体中分离本土极端嗜热嗜酸微生物，使其适应黄铜矿精矿的高矿浆密度，并确定它们在黄铜矿生物浸出中回收铜的效率。在本研究中，在常温下从伊朗的萨尔切什梅铜矿综合体采集样本。将混合样本接种到培养基中以富集微生物。通过将液体培养物继代培养到固体培养基上，从这些富集培养物中获得纯培养物。在扫描电子显微镜下进行形态观察。分离物适应30%（w/v）的矿浆密度。对于生物浸出试验，使用DX7软件设计实验。生物浸出实验在锥形瓶和搅拌槽反应器中进行。在锥形瓶中，当矿浆为15%、接种量为20%、颗粒尺寸为90μm且转速为160rpm时，最高铜回收率为39.46%。28天后，当矿浆为20%、接种量为20%、颗粒尺寸为40μm且转速为140rpm时，最低回收率为3.81%。在反应器中，铜回收率为32.38%。通过X射线衍射（XRD）方法对生物浸出残渣进行分析。结果表明，在生物浸出实验中未形成黄钾铁矾（KFe(SO)(OH)）。在我们的研究中，锥形瓶和搅拌槽反应器中各种菌种之间的拮抗反应以及大量浮游细胞似乎是铜回收率低的原因。
