In this study, we propose a novel temperature-programmed ammonium chloride (NH4Cl) roasting–water-leaching process to extract nickel (Ni), cobalt (Co), and copper (Cu) from polymetallic sulfide minerals in a synchronous, efficient, and environment-friendly manner. During the roasting process, several vital parameters were investigated to achieve the high co-sulfation of Ni, Co, and Cu. The dosage of NH4Cl was drastically reduced, and chlorine-free calcine was obtained using a chlorination–sulfation roasting schedule. The results suggest that the water-leaching yields of Ni, Co, and Cu reached ~ 97, ~ 95, and ~ 99 pct, respectively, whereas that of iron was ~ 1 pct under the following optimized conditions: the first roasting step temperature was 250 °C, the heating rate was 2 °C/min, the dosage of the NH4Cl additive was 80 mg/g(ore), the holding times at 250 °C and 650 °C were 120 and 60 minutes, respectively, and the particle size of the NH4Cl additive was smaller than 75 μm. The phase evolution as well as the chlorination and sulfation mechanisms during the three-step roasting process were examined by the roasting–leaching experiments and the X-ray diffraction, energy-dispersive X-ray spectroscopy, and thermodynamic calculations. The results indicate that sulfide chlorination occurred because of the NH4Cl additive and the formed intermediates, including metal chlorides and chlorine gas. The chlorides of Ni, Co, and Cu were successfully transformed into sulfates. The temperature-programmed NH4Cl roasting–water-leaching process considerably improves the selective sulfation of the nonferrous metals. Furthermore, this is a promising technique for separating and extracting nonferrous metals from iron-based sulfide materials.

中文翻译：

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一种用于多金属硫化物矿物中镍、钴和铜的高效共硫酸化的新型氯化铵焙烧方法

在这项研究中，我们提出了一种新型的程序升温氯化铵 (NH4Cl) 焙烧-水浸工艺，以同步、高效和高效的方式从多金属硫化物矿物中提取镍 (Ni)、钴 (Co) 和铜 (Cu)。环保的方式。在焙烧过程中，研究了几个重要参数以实现 Ni、Co 和 Cu 的高共硫酸化。NH4Cl 的用量显着减少，并且使用氯化-硫酸化焙烧程序获得了无氯煅烧物。结果表明，在以下优化条件下，Ni、Co 和 Cu 的水浸率分别达到 ~ 97、95 和 99 pct，而铁的水浸率约为 1 pct：第一焙烧步骤温度为250℃，升温速率2℃/min，NH4Cl添加剂用量80mg/g（矿石），250℃和650℃保温时间分别为120和60分钟，NH4Cl添加剂粒径小于75μm。通过焙烧-浸出实验和 X 射线衍射、能量色散 X 射线光谱和热力学计算，研究了三步焙烧过程中的相演变以及氯化和硫酸化机制。结果表明，由于NH4Cl添加剂和形成的中间体，包括金属氯化物和氯气，发生了硫化物氯化。Ni、Co 和 Cu 的氯化物成功转化为硫酸盐。程序升温的 NH4Cl 焙烧-水浸工艺大大提高了有色金属的选择性硫酸盐化。此外，