Conversion of ferric oxide to magnetite by hydrothermal reduction in Bayer digestion process  

拜耳法溶出过程中氧化铁水热还原转化为磁铁矿（英文）

作　　者：李小斌[1] 刘楠[1] 齐天贵[1,2] 王一霖[1] 周秋生[1] 彭志宏[1] 刘桂华[1] 

机构地区：[1]中南大学冶金与环境学院,长沙410083 [2]中铝中州铝业有限公司,焦作454000

出　　处：《Transactions of Nonferrous Metals Society of China》2015年第10期3467-3474,共8页中国有色金属学报（英文版）

基　　金：Project(51374239)supported by the National Natural Science Foundation of China

摘　　要：Digesting aluminum-bearing minerals and converting ferric oxide to magnetite simultaneously in Bayer digestion process is crucially important to deal with high-iron diasporic bauxite economically for alumina production.The reaction behaviors of hydrothermal reduction of ferric oxide in alkali solution were studied by both thermodynamic calculation and experimental investigation.The thermodynamic calculation indicates that Fe3O4 can be formed by the conversion of Fe2O3 at proper redox potentials in alkaline solution.The experimental results show that the formation ratio of Fe3O4 either through the reaction of Fe and Fe2O3 or through the reaction of Fe and H2O in alkaline aqueous solution increases remarkably with raising the temperature and alkali concentration,suggesting that Fe（OH）3- and Fe（OH）4- form by dissolving Fe and Fe2O3,respectively,in alkaline aqueous solution and further react to form Fe3O4.Moreover,aluminate ions have little influence on the hydrothermal reduction of Fe2O3 in alkaline aqueous solution,and converting iron minerals to magnetite can be realized in the Bayer digestion process of diasporic bauxite.在铝土矿拜耳法溶出的同时使赤铁矿转化为磁铁矿对高铁铝土矿的经济高效利用至关重要。在热力学计算的基础上,实验研究氧化铁在碱溶液中的水热还原行为。热力学计算结果表明:在适当的氧化还原电位条件下,氧化铁在碱性溶液体系中可转化为磁铁矿。实验结果表明:铁粉与氧化铁粉或者铁粉与水在碱性水溶液中反应形成四氧化三铁,反应转化率均随温度和碱浓度的升高而显著升高,这说明四氧化三铁的形成过程可能经历铁粉和氧化铁粉溶解分别形成含铁离子Fe(OH)3-和Fe(OH)4-,Fe(OH)3-和Fe(OH)4-进一步反应生成四氧化三铁两个过程。同时,铝酸根对氧化铁在碱溶液中的水热还原没有显著影响,在其拜耳法溶出过程中一水硬铝石中的铁矿物可以转化为磁铁矿。

关 键 词：Bayer process DIGESTION hydrothermal reduction ferric oxide MAGNETITE 

分 类 号：TF51[冶金工程—钢铁冶金]