Abstract

In this study, the effect of graphite on sphalerite dissolution was investigated using a Leptospirillum ferrooxidans (L. ferrooxidans) dominated meso-acidophilic bacterial consortium. Results of the studies indicated that Zn dissolution enhanced from 18.75% (in control tests) to 78.46% (using L. ferrooxidans) without graphite in the system (the conventional approach). Addition of graphite further improved sphalerite bio-oxidation up to 10%, i.e., from 78.46 to 87.83% indicating bio-catalytic effect and possible galvanic interaction between sphalerite and graphite. Through the conventional route, the system’s pH eventually lowered from 1.8 to 1.4 and ORP increased from 300 to 700 mV. In presence of graphite, the pH lowered to nearly 1.0 and ORP reached 600 mV. This indicated efficient bacterial activity and stabilized leaching conditions in both cases. Analytical characterization studies through XRD and SEM-EDAX indicated the presence of sulfur and K-type jarosite (KFe³⁺₃(OH)₆(SO₄)₂), ascribed to the passivation layers formed during sphalerite bioleaching.

摘要

在这项研究中，石墨对闪锌矿溶解的影响使用氧化亚铁钩端螺旋体 (L. ferrooxidans)为主的中嗜酸细菌聚生体进行了研究。研究结果表明，Zn 溶解度从 18.75%（在对照试验中）提高到 78.46%（使用L. ferrooxidans) 系统中没有石墨（传统方法）。石墨的添加进一步将闪锌矿的生物氧化率提高到 10%，即从 78.46% 提高到 87.83%，这表明了闪锌矿和石墨之间的生物催化作用和可能的电流相互作用。通过常规路线，系统的 pH 值最终从 1.8 降低到 1.4，ORP 从 300 提高到 700 mV。在石墨的存在下，pH 降低到接近 1.0，ORP 达到 600 mV。这表明在这两种情况下有效的细菌活性和稳定的浸出条件。通过 XRD 和 SEM-EDAX 进行的分析表征研究表明存在硫和 K 型黄钾铁矾 (KFe ³⁺ ₃ (OH) ₆ (SO ₄ ) ₂），归因于闪锌矿生物浸出过程中形成的钝化层。