铝土矿溶出条件对铝酸钠溶液结构影响的研究

【作者】 张少云；

【导师】 刘云清；

【作者基本信息】 中南大学 ， 物理化学， 2010， 硕士

【摘要】 过饱和铝酸钠溶液分解是氧化铝生产的重要工序,研究铝酸钠溶液结构可为氧化铝生产过程提供基础数据。本文采用IR、UV、Raman、XRD、SEM等现代分析测试手段,研究了浓度、苛性比对近似工业成分的铝酸钠溶液结构的影响,重点探讨了时间、温度、矿石类型对溶出的铝酸钠溶液结构的影响,以及温度对溶出液析出晶体的结构和形貌的影响。研究结论如下：1.苛性比一定,浓度较低时,近似工业成份的铝酸钠溶液主要以Al(OH)4-形态存在；浓度较高时,除以Al(OH)4-形态存在外,还存在[Al2O(OH)]62-等复杂的聚合铝酸根离子。2.氧化铝浓度一定,苛性比较低时,近似工业成份的铝酸钠溶液存在聚合铝酸根离子和离子对；苛性比较高时,主要以Al(OH)4-形态存在；在高苛性比、高苛碱浓度的铝酸钠溶液中存在Al(OH)63-和Al(OH)4-为主体的由氢键相连的缔合物。3.铝酸钠溶液结构在制备后的短时间内发生明显变化,主要成分Al(OH)4-先与水结合成水合铝酸根离子,然后转变成离子对和多种聚合物铝酸根离子,最后析出晶体。沙特铝土矿和晋南铝土矿的溶出液在析出晶体前和析出晶体后的结构相同,印尼铝土矿溶出液在析出晶体前存在多种聚合物成分,析出晶体后转变为较单一的聚合物。4.较低溶出温度下,铝酸钠溶液的主要阴离子是Al(OH)4-,较高溶出温度下,铝酸钠溶液中不仅存在Al(OH)4-,而且存在复合铝酸根离子；矿石类型影响溶出的铝酸钠溶液的结构,印尼铝土矿溶出液较晋南铝土矿溶出液,溶液中除了存在Al(OH)4-及二聚体离子外又出现了新的复杂聚合铝酸根离子。5.IR和XRD分析表明,溶出温度对晶体的结构无明显的影响,均为拜耳石型α-Al(OH)3结构；但晶体的形貌有较明显差异：较低溶出温度下,晶体较紧密；较高溶出温度下,晶体较疏松。更多还原

【Abstract】 Supersaturated sodium solution decomposition is an important process of alumina production. Research on the structures of sodium aluminum solution may provide basic data for the process of alumina production.Based on the IR, UV, Raman, XRD, SEM analysis and other modern analytical testing methods, the effects of concentration, alkali ratio on the structure of sodium aluminate solution as approximate industrial ingredients were investigated. Moreover, the influence of the dissolving-out temperature, bauxite type and time on the structure of sodium aluminate solution was studied. The influence of dissolving-out temperature on the structure and morphology of precipitation was also investigated.Conclusions are as follows:(1) When certain ak is involved, Al(OH)4 is the main ion at lower sodium aluminate concentration, while Al(OH)4-, [(HO)3Al-O-Al(OH)3]2-or more complex homopolymers exist at higher sodium aluminate concentration.(2) At a certain alumina concentration, polymers and ion pairs exists at lowerαk sodium aluminate solution; while main anion is Al(OH)4 at higherαk solution. At higher ak and higher concentration, Al(OH)63- and Al(OH)4 are the main species connected by hydrogen bonding.(3)The main species of Al(OH)4- in aluminate sodium solution combines with water hydration to form aluminate ions, which turns into various polymer aluminum metal ions and ion pairs after preparation a short time. The liquid structures of Shate bauxite and JinNan bauxite after precipitation are the same as those before precipitation. Liquid structure of YinNi bauxite is present as various polymers before precipitation, but turns into other ingredient or simplex polymer after precipitation.(4)The main anion of sodium aluminate solution is Al(OH)4 at lower dissolving-out temperature, while the anions are Al(OH)4- and [(HO)3Al-O-Al(OH)3]2- at higher dissolving-out temperature. Bauxite types have effect on the structure of sodium aluminate solution. Liquid structure of YinNi bauxite appears more complicate aluminate ions than JinNan bauxite.(5)Dissoving-out temperature have no obvious influence on the structure of sediment products ofα-Al(OH)3. The product is loose at higher dissoving-out temperature, while it is compact at lower dissoving-out temperature.更多还原