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以硝酸镁为氧化剂系统研究了硝酸根存在下红土镍矿在硫酸体系中的高压浸出情况。通过单因素条件实验详细考察了硝酸镁添加量、初始硫酸酸度、反应温度、保温时间和液固比对浸出结果的影响,并得到最优浸出工艺条件:硝酸镁加入量0.06 g·g~(-1),初始酸度140 g·L~(-1),反应温度220℃,保温时间60 min,液固比2 ml·g-1。在上述最优工艺条件下进行综合试验,取得了良好的浸出结果,实现了镍、钴和铁的选择性浸出,镍、钴浸出率分别为90.9%和91.7%,而铁浸出率低至2.2%。最后借助X射线衍射(XRD)、反射显微镜及化学物相分析,对新体系下浸出过程机制进行了研究,该体系中浸出过程为溶解—氧化—沉淀机制。添加硝酸根较传统硫酸高压浸出省酸,经计算利用该技术处理1 t红土矿可节省H2_SO_4大约160 kg。
Using magnesium nitrate as oxidant system, the high pressure leaching of lateritic nickel ore in sulfuric acid system was studied in the presence of nitrate. The influence of the addition amount of magnesium nitrate, the initial acidity of sulfuric acid, the reaction temperature, the holding time and the liquid-solid ratio on the leaching results were investigated in detail by single-factor experiments. The optimum conditions for the leaching were as follows: magnesium nitrate addition 0.06 g · g ~ -1). The initial acidity was 140 g · L -1, the reaction temperature was 220 ℃, the holding time was 60 min and the liquid-solid ratio was 2 ml · g -1. In the above optimum process conditions, a comprehensive test was carried out, and good leaching results were obtained. The selective leaching of nickel, cobalt and iron was achieved. The leaching rates of nickel and cobalt were 90.9% and 91.7% respectively, while the leaching rate of iron was as low as 2.2 %. Finally, the mechanism of leaching process under the new system was studied by means of X-ray diffraction (XRD), reflection microscope and chemical phase analysis. The leaching process was dissolution-oxidation-precipitation mechanism. Compared with conventional sulfuric acid, nitric acid is added to leach acid at a higher pressure, and the utilization of this technology to treat 1 t of laterite can save about 160 kg of H2_SO_4.