Effect of oxalate on seed precipitation of gibbsite from sodium aluminate solution  

草酸盐对铝酸钠溶液晶种分解过程氢氧化铝析出的影响

作　　者：YU Hai-yan ZHANG Bai-yong PAN Xiao-lin TU Gan-feng 于海燕;张佰永;潘晓林;涂赣峰(Key Laboratory for Ecological Metallurgy of Multimetallic Mineral of Ministry of Education,Northeastern University,Shenyang 110819,China;School of Metallurgy,Northeastern University,Shenyang 110819,China)

机构地区：[1]Key Laboratory for Ecological Metallurgy of Multimetallic Mineral of Ministry of Education,Northeastern University,Shenyang 110819,China [2]School of Metallurgy,Northeastern University,Shenyang 110819,China

出　　处：《Journal of Central South University》2020年第3期772-779,共8页中南大学学报（英文版）

基　　金：Projects(51774079,51674075)supported by the National Natural Science Foundation of China;Project(N182508026)supported by the Fundamental Research Funds for the Central Universities,China。

摘　　要：The precipitation performance and kinetics of gibbsite from sodium aluminate solution with different sodium oxalate concentrations as well as the corresponding influence mechanism of oxalate during the seed precipitation process were systematically investigated by physicochemical properties test,using SEM and Raman spectra.As the concentration of sodium oxalate increases,both the precipitation rate and particle size of gibbsite decrease.The presence of sodium oxalate not only increases the viscosity of sodium aluminate solution,but also promotes the transformation of Al(OH)4^? to Al2O(OH)6^2?.The overall reaction rate constant decreases and the apparent activation energy of gibbsite increases with the increasing sodium oxalate concentration,the rate controlling step of which is chemical reaction.The needle-like sodium oxalate precipitates on the gibbsite crystals and covers the active Al(OH)3 seed sites,which leads to the lower precipitation rate and the finer particle size of gibbsite during the seed precipitation process.采用物化性能测定、扫描电镜和拉曼光谱等手段系统研究了晶种分解过程铝酸钠溶液不同草酸钠浓度下氢氧化铝的析出行为和动力学及其影响机理。随着铝酸钠溶液浓度的增加,氢氧化铝的析出率和晶粒尺寸均逐渐降低。草酸钠的存在不仅增加铝酸钠溶液的黏度,而且促进Al(OH)4^?向Al2O(OH)6^2?的转变。随着草酸钠浓度的增加,氢氧化铝析出的反应速率常数降低,表观活化能增加,为化学反应控制。针状草酸钠在氢氧化铝晶体上析出,覆盖了活性晶种的位置,导致晶种分解过程中氢氧化铝分解率降低、晶粒细化。

关 键 词：sodium oxalate sodium aluminate solution gibbsite precipitation KINETICS Raman spectra 

分 类 号：TQ133.1[化学工程—无机化工]