Oxidative leaching is an inexpensive alternative to using chemical cyanide extraction methods for gold from low-grade gold sulfide. Oxidation of finely ground gold-bearing ore by Acidithiobacillus ferrooxidans was evaluated in terms of cell density, pH, and leaching efficiency of Fe and Au in shake flask experiments. The compositional and elemental analyses of the beneficiated ore were analyzed using XRD and EDXRF spectroscopy. The ore’s primary constituents are gold (4.356 mg/L), silicon, iron, and sulfur (62.456, 15.441, and 7.912 wt%, respectively). XRD spectra, the main phases of the concentrated ore, showed that the major components of the ore were quartz, syn, silicon sulfide, pyrite, and polymetallic elements such as silderenrite, gismondine, siderenikite, hematite, and syn. The experimental results, with Acidithiobacillus ferrooxidans bacteria and blank, were evaluated. The pH of the blank remained nearly constant, and the pH of the bioleached was occasionally lowered. The A. ferrooxidans strain always grew better throughout the bioleaching process. For the A. ferrooxidans strain, the cell density of cells reached a maximum of 90.00 × 10⁶ cells/mL after the 11^th week and decreased to 87.00 × 10⁶ cells/mL after the 12^th week. The decrease in cell density may be due to the presence of polymetallic elements such as Al, Cr, Ti, and Ni, leading to reduced metal tolerance of the A. ferrooxidans strain. In the A. ferrooxidans leaching process, the maximum total iron and gold extraction reached 92.16% (14.23 mg/L) and 99.97% (4.355 ppm), respectively, after the 11^th week, and leaching tends to decrease up to 14 weeks, which may be due to the formation of secondary minerals. More research will be performed to optimize the procedure and leaching kinetic, examine the impact of metal content, and take into account the potential for bioleaching process pollution in addition to the amount of gold recovered.

中文翻译：

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氧化亚铁硫杆菌从埃塞俄比亚提格雷梅-希贝矿床中浸出硫化硅金矿石

氧化浸出是使用化学氰化物从低品位硫化金中提取金的廉价替代方法。在摇瓶实验中，根据细胞密度、pH 值以及铁和金的浸出效率，评估了氧化亚铁硫杆菌对细磨含金矿石的氧化作用。使用 XRD 和 EDXRF 光谱对选矿矿石的成分和元素进行了分析。该矿石的主要成分是金（4.356 mg/L）、硅、铁和硫（分别为 62.456、15.441 和 7.912 wt%）。精矿主物相XRD谱显示，矿石主要成分为石英、顺式、硫化硅、黄铁矿，以及硅铁矿、辉铁矿、铁铁镍矿、赤铁矿、顺式等多金属元素。对氧化亚铁硫杆菌细菌和空白的实验结果进行了评价。空白的pH值几乎保持恒定，并且生物浸出物的pH值偶尔会降低。在整个生物浸出过程中，氧化亚铁菌株总是生长得更好。对于氧化亚铁菌株，第¹¹周后细胞密度达到最大值90.00×10 ^{6 个} 细胞/mL ，第¹²周后下降至87.00×10 ^{6 个} 细胞/mL  。细胞密度的降低可能是由于铝、铬、钛和镍等多金属元素的存在，导致氧化亚铁菌株的金属耐受性降低。在A.氧化亚铁浸出过程中，第¹¹周后，总铁和金的最大提取率分别达到92.16%（14.23 mg/L）和99.97%（4.355 ppm），并且浸出量在14周之前趋于下降。这可能是由于次生矿物的形成造成的。将进行更多研究来优化程序和浸出动力学，检查金属含量的影响，并除了回收的金量之外还考虑生物浸出过程污染的可能性。