摘要
Thermodynamic diagrams of Na−S−Fe−H_(2)O system were constructed to analyze the behavior of sulfur and iron in the Bayer process.After digestion,iron mainly exists as Fe_(3)O_(4) and Fe_(2)O_(3) in red mud,and partial iron transfers into solution as Fe(OH)_(3)^(−),HFeO_(2)^(−),Fe(OH)_(4)^(−)and Fe(OH)_(4)^(2−).The dominant species of sulfur is S^(2−),followed by SO_(4)^(2−),and then SO_(3)^(2−)and S_(2)O_(3)^(2−).The thermodynamic analysis is consistent with the iron and sulfur species distribution in the solution obtained by experiments.When the temperature decreases,sulfur and iron can combine and precipitate.Controlling low potential and reducing temperature are beneficial to removing them from the solution.XRD patterns show that NaFeS_(2)·2H_(2)O,FeS and FeS_(2) widely appear in red mud and precipitates of pyrite and high-sulfur bauxite digestion solution.Thermodynamic analysis can be utilized to guide the simultaneous removal of sulfur and iron in the Bayer process.
构建Na−S−Fe−H_(2)O系热力学图,分析拜耳法生产过程中硫和铁的行为。溶出后,铁最可能以Fe_(3)O_(4)和Fe_(2)O_(3)的形式进入赤泥,部分铁以Fe(OH)_(3)^(−)、HFeO_(2)^(−)、Fe(OH)_(4)^(−)和Fe(OH)_(4)^(2−)的形式转入液相。硫的优势物种是S^(2−),其次是SO_(4)^(2−),然后是SO_(3)^(2−)和S_(2)O_(3)^(2−)。热力学分析结果与实验测得的溶液中铁和硫的形态分布一致。当温度降低时,硫和铁会结合析出。控制低电位和降低温度均有利于将硫和铁从溶液中脱除。XRD谱表明,NaFeS_(2)·2H_(2)O、FeS和FeS_(2)广泛存在于赤泥以及黄铁矿和高硫铝土矿溶出液的析出物中。热力学分析可用于指导拜耳法同步除硫和铁。
基金
the financial supports from the National Natural Science Foundation of China(No.51904052)
the Chongqing Research Program of Basic Research and Frontier Technology,China(No.cstc2020jcyjmsxm X0476)
the Science and Technology Research Program of Chongqing Municipal Education Commission,China(No.KJQN201901508)
the Graduate Science and Technology Innovation Training Program of Chongqing University of Science and Technology,China(No.YKJCX2020201)。
