Heap leaching of laterites for extraction of nickel and cobalt is an attractive alternative to capital and energy intensive high pressure acid leaching, the dominant hydrometallurgical processing technology for limonitic laterites. Conventional approach for heap leaching of laterites is leaching with sulfuric acid. Consumption of sulfuric acid during heap leaching is substantial and industrial-scale operations require construction of a sulfuric acid production plant on site. In this study, heap bioleaching of laterites was simulated in laboratory scale column percolators and bioleaching of nickel and cobalt from lateritic material was successfully demonstrated for the first time. The process is based on biooxidation of the bacterially modified “wet sulfur” inside column percolators by sulfur-oxidizing acidophilic bacteria Acidithiobacillus thiooxidans. The “wet sulfur“ was generated in a bioreactor with the bacterial culture, harvested, and mixed with lateritic ore before forming agglomerates to be filled in the percolator columns. Liquid was circulated with a flow rate of 8 mL/min. Maximum metal extraction was 66% nickel, 95% cobalt, 10% iron, 55% magnesium and 89% manganese from the Piauí lateritic ore after one month bioleaching. For comparison, chemical leaching with 1 M sulfuric acid with or without addition of 10 g/L of ferrous sulfate heptahydrate as reductant resulted in extraction of approximately 80% nickel, 86% cobalt, 33% iron, 50% magnesium and 81% manganese. With bioleaching a higher cobalt but lower nickel and iron extraction was achieved, i.e. a better selectivity of nickel over iron extraction, as well as a relatively higher pH of the pregnant leach solution requiring less limestone and, consequently, lower CO₂ emission and generation of iron cake waste in case of laterite bioleaching. Overall, the results are promising and show potential of laterite heap bioleaching to be further developed to application on industrial scale.

用于提取镍和钴的红土矿堆浸是资本和能源密集型高压酸浸的一种有吸引力的替代方案，高压酸浸是褐铁矿红土的主要湿法冶金加工技术。红土堆浸的传统方法是用硫酸浸出。堆浸过程中硫酸的消耗量很大，工业规模的操作需要在现场建造硫酸生产厂。在这项研究中，在实验室规模的柱渗滤器中模拟了红土的堆生物浸出，并首次成功演示了从红土材料中生物浸出镍和钴。该过程基于硫氧化嗜酸性细菌氧化硫硫杆菌对柱渗滤器内经过细菌修饰的“湿硫”的生物氧化。“湿硫磺”是在生物反应器中通过细菌培养物产生的，收获后与红土矿石混合，然后形成团块填充到渗滤器柱中。液体以8mL/min的流速循环。经过一个月的生物浸出后，皮奥伊红土矿石中的最大金属提取率为 66% 镍、95% 钴、10% 铁、55% 镁和 89% 锰。为了进行比较，使用 1 M 硫酸进行化学浸出，添加或不添加 10 g/L 七水硫酸亚铁作为还原剂，可提取出约 80% 的镍、86% 的钴、33% 的铁、50% 的镁和 81% 的锰。通过生物浸出，实现了更高的钴提取率和更低的镍和铁提取率，即镍相对于铁提取具有更好的选择性，并且母浸出液的 pH 值相对较高，需要较少的石灰石，因此，较低的 CO ₂排放和生成红土生物浸出时的铁饼废料。总体而言，结果是有希望的，并显示了红土堆生物浸出进一步发展到工业规模应用的潜力。