Nitric acid pressure leaching of limonitic laterite ores: Regeneration of HNO 3 and simultaneous synthesis of fibrous Ca
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Nitric acid pressure leaching of limonitic laterite ores: Regeneration of HNO3 and simultaneous synthesis of fibrous CaSO4·2H2O by-products SHAO Shuang(邵爽)1, 2, MA Bao-zhong(马保中)1, 2, 3, WANG Xin(王昕)2, ZHANG Wen-juan(张文娟)1, 2, 3, CHEN Yong-qiang(陈永强)1, 2, 3, WANG Cheng-yan(王成彦)1, 2, 3 1. State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China; 2. School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China; 3. Beijing Key Laboratory of Green Recycling and Extraction of Metals, Beijing 100083, China © Central South University Press and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract: An innovative technology, nitric acid pressure leaching of limonitic laterite ores, was proposed by our research team. The HNO3 regeneration is considerable significance for the improvement of the proposed technology and its commercial application, but it has not been systematically investigated. Herein, regenerating HNO3 from Ca(NO3)2 solution with low-cost H2SO4, and simultaneous synthesis of fibrous CaSO4·2H2O by-products were studied. As a theoretical basis, the solubility of CaSO4·2H2O in HNO3 medium is studied. It is concluded that the solubility of CaSO4·2H2O increases with increasing temperature or increasing HNO3 concentration, which has considerable guiding significance for the subsequent experimental research and analysis. Then, the effects of various factors on the residual Ca2+ concentration of filtrate, the regenerated HNO3 concentration and the morphology of synthesized products are investigated using ICP-AES and SEM. And the effect mechanism is also analyzed. The results indicate the regenerated HNO3 concentration reaches 116 g/L with the residual Ca2+ concentration being 9.7 g/L at the optimum conditions. Moreover, fibrous CaSO4·2H2O by-products with high aspect ratios (length, 406.32 μm; diameter, 14.71 μm; aspect ratio, 27.62) can be simultaneously synthesized. Key words: limonitic laterite ores; Ca(NO3)2 solution; HNO3 regeneration; CaSO4·2H2O by-products; solubility Cite this article as: SHAO Shuang, MA Bao-zhong, WANG Xin, ZHANG Wen-juan, CHEN Yong-qiang, WANG Cheng-yan. Nitric acid pressure leaching of limonitic laterite ores: Regeneration of HNO3 and simultaneous synthesis of fibrous CaSO4·2H2O by-products [J]. Journal of Central South University, 2020, 27(): . DOI: https://doi.org/10.1007/s11771-020-4463-2.
1 Introduction At present, high pressure acid leaching and reducing roasting–atmospheric acid leaching are mainly applied to treat limonitic laterite ores [1, 2]. Ni/Co recovery is achieved by precipitation, and
chelating ion exchange resins with high selectivity [3]. Nitric acid is a widely used leaching agent with strong oxidizability, which can sufficiently oxidize the divalent iron to hematite while dissolving valuable metals [4, 5]. So, nitric acid was selected and developed to treat limonitic laterite ores by our research team [4, 5]. And a series of laboratory tests
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