Journal of Sustainable Metallurgy ( IF 2.5 ) Pub Date : 2022-04-25 , DOI: 10.1007/s40831-022-00529-5 Manish Kumar Sinha 1 , Rian Jordaan 1 , Walter Purcell 1
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The leaching behavior of manganese from ferruginous manganese ore in sulphuric acid solution using sodium dithionite as a reducing agent was investigated. The optimum sulphuric acid concentration, leaching time, temperature, pulp density and agitation speed for leaching of manganese was determined. Complete manganese leaching was observed under the optimized conditions of 0.6 M H2SO4, 0.49 M sodium dithionite, 200 g/L pulp density, 60 °C leaching temperature, 600 rpm stirring rate and 120 min reaction time. The leaching kinetics and dissolution process have also been analyzed by model fitting and microstructural observation. The kinetics of reductive leaching of manganese ores by sodium dithionite in dilute sulphuric acid did not follow a shrinking core kinetic model. The Avrami model was used successfully to explain the kinetic data. The positive values of both ∆H and ∆S indicates that the leaching process is endothermic and random while the negative values of ∆G indicate that manganese dissolution process is spontaneous in nature. After removal of impurities from the leach solution by precipitation, a high purity (99.2%) α-Mn2O3 was synthesized from the concentrated Mn solution. The as-synthesized manganese oxide powder was characterized by chemical analysis, SEM–EDS and XRD analysis. The present process would be a key technology for reductive leaching of manganese oxide ores in an economical and efficient way.
Graphical Abstract
中文翻译：
连二亚硫酸钠还原酸浸出铁锰矿湿法冶金回收锰
以连二亚硫酸钠为还原剂，研究了含铁锰矿中锰在硫酸溶液中的浸出行为。确定了锰浸出的最佳硫酸浓度、浸出时间、温度、矿浆密度和搅拌速度。在0.6 MH 2 SO 4的优化条件下观察到锰完全浸出, 0.49 M 连二亚硫酸钠, 200 g/L 纸浆密度, 60 °C 浸出温度, 600 rpm 搅拌速度和 120 min 反应时间。还通过模型拟合和微观结构观察分析了浸出动力学和溶解过程。连二亚硫酸钠在稀硫酸中还原浸出锰矿石的动力学不遵循缩芯动力学模型。Avrami 模型成功地用于解释动力学数据。ΔH和ΔS的正值表明浸出过程是吸热的和随机的，而ΔG的负值表明锰的溶解过程是自发的。通过沉淀从浸出液中去除杂质后，得到高纯度（99.2%）的 α-Mn2 O 3由浓Mn溶液合成。通过化学分析、SEM-EDS 和 XRD 分析对合成的氧化锰粉末进行了表征。本工艺将成为经济有效地还原浸出氧化锰矿石的关键技术。
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