Bio-oxidation of refractory sulfidic gold minerals has been applied at the commercial scale as a pre-treatment to improve gold yields and reduce chemical consumption during gold cyanidation. In this study, the effect of initial cell concentration on the oxidation of pyritic gold ore was evaluated with four aerated bioreactors at 30 °C with 10% pulp density and pH maintained at 1.4 with NaOH. Results of NaOH consumption and changes in soluble Fe and S concentrations indicated that increasing the initial cell concentration from 2.3 × 10⁷ to 2.3 × 10¹⁰ cells mL⁻¹ enhanced pyrite oxidation during the first week. However, by day 18 the reactor with the lowest initial cell concentration showed profound performance enhancement based on soluble Fe and S concentrations, sulfide-S and pyrite contents in the residues, and subsequent gold leaching of the bio-oxidation residues by cyanidation. Overall, the results showed that the cell concentration was clearly beneficial during the initial stages of oxidation (first 7–8 days).

中文翻译：

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金氰化前初始细胞浓度对黄铁矿生物氧化的影响

难熔硫化金矿物的生物氧化已在商业规模上用作预处理，以提高金产量并减少金氰化过程中的化学品消耗。在这项研究中，使用四个曝气生物反应器在 30°C、10% 的纸浆密度和 1.4 的 NaOH 溶液中评估初始细胞浓度对黄铁矿氧化的影响。NaOH 消耗和可溶性 Fe 和 S 浓度变化的结果表明，将初始细胞浓度从 2.3 × 10 ⁷增加到 2.3 × 10 ^{10 个}细胞 mL ^-1在第一周增强黄铁矿氧化。然而，到第 18 天，基于可溶性 Fe 和 S 浓度、残留物中硫化物-S 和黄铁矿含量以及随后通过氰化作用对生物氧化残留物进行金浸出，具有最低初始细胞浓度的反应器表现出显着的性能增强。总体而言，结果表明细胞浓度在氧化的初始阶段（前 7-8 天）显然是有益的。