Abstract

Nickel is mostly extracted from sulfide ores, however, laterite ores account for over 60 pct of all nickel resources in the world, and despite its predominance, there is no well-established process to extract nickel from such ores. Nickel in laterites is hosted in many different compounds such as oxides, hydroxides, and silicates minerals. The sulfation-roasting-leaching process has the potential to change this scenario once it can be applied to all kinds of nickel laterite ores and does not consume much acid, as in the atmospheric leaching process. The main characteristic of the process is the iron sulfates decomposition during roasting steps, which produces sulfur trioxide (SO₃). The sulfur trioxide is reactive with metals such as nickel and cobalt, converting them to soluble sulfates, and reducing acid consumption. Experiments were conducted to establish the optimal conditions to extract nickel from laterite ores using the sulfation-roasting-leaching process. Various parameters were investigated: water addition, sulfuric acid concentration, the number of heat-treatments steps, roasting temperature and time, leaching time, and solid/liquid ratio. Furthermore, the phase changes during thermal treatments were investigated to identify the mechanisms involved in the transformation of the minerals. Experimental results indicated that nickel forms sulfates through three different ways: reacting with H₂SO₄ during sulfation, with Fe₂(SO₄)₃ (ferric sulfate) or Fe(OH)SO₄ (basic iron sulfates) during the heat-treatments, and also throughout the leaching step due to iron-rich phase dissolution. More than 83.0 pct Ni, 90.0 pct Co, 61.3 pct Al, 17.3 pct Ca, 85.7 pct Mg, 87.5 pct Mn, 1.1 pct Ti, and 16.6 pct Fe were extracted under optimums conditions.

Graphic Abstract

中文翻译：

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镍红土矿的焙烧和浸出行为

摘要

镍主要是从硫化矿石中提取的，但是，红土矿石占全球所有镍资源的60％以上，尽管占主导地位，但尚无完善的方法可从此类矿石中提取镍。红土中的镍存在于许多不同的化合物中，例如氧化物，氢氧化物和硅酸盐矿物。一旦将其应用于各种镍红土矿石，并且不像大气浸出过程那样消耗大量酸，则硫酸盐焙烧-浸出过程就有可能改变这种情况。该方法的主要特征是在焙烧步骤中硫酸铁分解，生成三氧化硫（SO ₃）。三氧化硫可与金属（例如镍和钴）反应，将它们转化为可溶性硫酸盐，并减少酸消耗。进行了实验，以建立采用硫酸盐焙烧-浸出工艺从红土矿石中提取镍的最佳条件。研究了各种参数：加水量，硫酸浓度，热处理步骤数，焙烧温度和时间，浸出时间以及固液比。此外，对热处理过程中的相变进行了研究，以确定与矿物转化有关的机制。实验结果表明，镍通过三种不同的方式形成硫酸盐：硫酸化过程中与H ₂ SO ₄反应，与Fe ₂（SO₄）₃（硫酸铁）或Fe（OH）SO ₄（碱式硫酸铁）在热处理过程中以及由于富铁相溶解而在整个浸出步骤中也是如此。在最佳条件下提取了超过83.0％的Ni，90.0％的Co，61.3％的Al，17.3％的Ca，85.7％的Mg，87.5％的Mn，1.1％的Ti和16.6％的Fe。

图形摘要