Abstract This study investigates the influence of salinity on the bioleaching efficiency of a copper‑nickel‑cobalt bearing sulphidic tailing obtained from Golgohar iron ore desulphurization plant (Sirjan, Iran). The effects of several critical parameters including, suspension pH, nutrient medium, microorganism type, and pulp density were investigated on the extraction of copper, cobalt and nickel from the sulphidic tailing at different levels of sodium chloride concentration. Bioleaching efficiency was also evaluated in the presence of saline local and process waters. Results showed that maximum extraction of nickel (87%) and cobalt (69%) was achieved at the initial pH of 1.8, the pulp density of 10%, Norris nutrient medium containing 10 g/L sodium chloride, and using moderately thermophilic microorganisms. However, maximum copper extraction (~90%) was obtained in the presence of local water. It was also found that the local and process waters containing around 15.5 and 8.3 g/L chloride ions, respectively, increased metal extraction about 25% and 10% in comparison to distilled water at the first two days. Nevertheless, the metal extraction decreased at the end of the process in both water types mainly due to the formation of gypsum and jarosite precipitates, which were found by SEM/EDS analyses. Furthermore, at the initial pH of 1.5, the extraction of valuable metals was significantly improved (20–60% increase at first 9 days) in the presence of 5 g/L sodium chloride; whereas a further increase (to 10 g/L sodium chloride) had a negative effect on the extractions. Increasing the pulp density from 5% (w/v) to 10% decreased the nickel and cobalt extraction about 26% and 21%, respectively; however, copper extraction increased around 5% which could be related to the lower level of oxidation-reduction potential of the suspension at the higher pulp density. It can be concluded that the low levels of salinity (up to 5 g/L sodium chloride addition) could have a positive effect on the efficiency of the bioleaching process.

中文翻译：

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水盐度对伊朗戈尔戈哈尔铁矿硫化尾矿铜、镍和钴生物浸出的影响

摘要 本研究调查了盐度对从 Golgohar 铁矿石脱硫厂（伊朗锡尔詹）获得的含铜镍钴硫化尾矿的生物浸出效率的影响。研究了几个关键参数（包括悬浮液 pH 值、营养介质、微生物类型和纸浆密度）对在不同氯化钠浓度水平下从硫化尾矿中提取铜、钴和镍的影响。还在当地盐水和工艺用水存在的情况下评估了生物浸出效率。结果表明，当初始 pH 值为 1.8、纸浆密度为 10%、Norris 营养培养基含有 10 g/L 氯化钠并使用中等嗜热微生物时，镍 (87%) 和钴 (69%) 的提取率最高。然而，在当地水存在的情况下获得了最大的铜提取率（~90%）。还发现，与前两天的蒸馏水相比，分别含有约 15.5 和 8.3 g/L 氯离子的本地和工艺用水使金属提取增加了约 25% 和 10%。尽管如此，在两种水类型的过程结束时，金属提取量均下降，这主要是由于形成了石膏和黄钾铁矾沉淀物，SEM/EDS 分析发现了这些沉淀物。此外，在 1.5 的初始 pH 值下，在 5 g/L 氯化钠的存在下，有价值金属的提取显着提高（前 9 天增加了 20-60%）；而进一步增加（至 10 g/L 氯化钠）会对萃取产生负面影响。将矿浆密度从 5% (w/v) 增加到 10%，镍和钴的提取量分别降低了约 26% 和 21%；然而，铜提取量增加了约 5%，这可能与较高纸浆密度下悬浮液的氧化还原电位水平较低有关。可以得出结论，低盐度（添加高达 5 g/L 氯化钠）可能对生物浸出过程的效率产生积极影响。