低铁赤泥一步碱热法高效回收有价元素  

Efficient recovery of valuable elements from low-iron red mud by one-step alkali-digestion process

作　　者：谢仪美 姜祉伸 杨喜童 伊力亚尔·白合提 潘晓林 XIE Yi-mei;JIANG Zhi-shen;YANG Xi-tong;BAIHETI Yi-liyaer;PAN Xiao-lin(School of Metallurgy,Northeastern University,Shenyang 110819,China;Key Laboratory for Recycling of Nonferrous Metal Resources(Shenyang),Shenyang 110819,China)

机构地区：[1]东北大学冶金学院,沈阳110819 [2]沈阳市有色金属资源循环利用重点实验室,沈阳110819

出　　处：《中国有色金属学报》2023年第12期4265-4275,共11页The Chinese Journal of Nonferrous Metals

基　　金：国家大学生创新创业训练计划资助项目(221151);国家自然科学基金资助项目(51774079,22078055)。

摘　　要：基于高效脱硅产物钙铁榴石,采用一步碱热法回收低铁赤泥中的碱和氧化铝,系统分析了不同条件下赤泥在碱热转化过程中的热动力学、物相演变机制和有价元素回收规律。结果表明,增加原料铁铝比能够提高赤泥中氧化铝的回收率,而氧化钠回收率先降低后增高;增加钙硅比,氧化钠回收率逐渐提高,而氧化铝回收率先增高后降低;增加苛性碱质量浓度和分子比、升高反应温度和延长反应时间均能够提高赤泥中氧化钠和氧化铝回收率。低铁赤泥高效碱热转化推荐工艺为:铁铝比0.6,钙硅比2.4,反应温度260℃,时间45 min,碱液苛性碱质量浓度245 g/L、分子比30。此时,氧化钠和氧化铝回收率分别为95.53%和57.53%。赤泥主要脱硅产物水合铝硅酸钠和水化石榴石在碱热转化过程中转化为钙铁榴石,氧化钠和氧化铝碱热转化过程主要由界面传输和扩散控制,其反应表观活化能分别为41.07 kJ/mol和42.78 kJ/mol。Based on the high efficiency desilication product of hydroandradite,sodium oxide and alumina were recovered from low-iron red mud by the one-step alkali-digestion process.The thermodynamic and kinetic analyses,phase evolution mechanism as well as the recoveries of alkali and alumina from red mud were systematically investigated under different conditions during the alkali-digestion conversion process.The increase of iron-to-alumina ratio enhances the recovery efficiency of alumina,and the recovery efficiency of sodium oxide first decreases and then increases.As the calcium-to-silicon ratio increases,the recovery efficiency of sodium oxide increases gradually,while the recovery efficiency of alumina increases first and then decreases.The recovery efficiencies of sodium oxide and alumina are increased by increasing the mass concentration of caustic and molecular ratio,rising the reaction temperature as well as prolonging the reaction time.The optimal conditions are as follows:the iron-to-alumina ratio is 0.6,calcium-to-silicon ratio is 2.4,alkali solution concentration is 245 g/L,caustic ratio is 30,reaction temperature is 260 ℃,reaction time is 45 min,and the corresponding recovery efficiencies of sodium oxide and alumina are 95.53% and 57.53%,respectively.The main desilication products in red mud,sodium aluminosilicate hydrate and hydrogarnet,are converted into hydroandradite during the alkali-digestion conversion.The reaction kinetics of sodium oxide and alumina recovery correspond to the control of interface transfer and diffusion across the product layer,and the apparent activation energies are 41.07 kJ/mol and 42.78 kJ/mol,respectively.

关 键 词：赤泥 碱热转化 钙铁榴石 氧化铝 氧化钠 动力学 

分 类 号：TF821[冶金工程—有色金属冶金]