硼精矿加压碱解与结晶制备偏硼酸钠的动力学  

Kinetics of Alkaline Leaching of Boron Concentrate and Crystallization of NaB(OH)_4

作　　者：殷保稳[1,2,3] 秦士跃[2] 张亦飞[2] 张懿[2] 

机构地区：[1]天津大学化工学院,天津300072 [2]中国科学院过程工程研究所湿法冶金清洁生产技术国家工程实验室,北京100190 [3]精馏技术国家工程研究中心,天津300072

出　　处：《过程工程学报》2014年第3期388-394,共7页The Chinese Journal of Process Engineering

基　　金：国家自然科学基金资助项目(编号:21276258);国家高技术研究发展计划(863)基金资助项目(编号:2011AA060701)

摘　　要：对硼精矿在NaOH-H2O体系的分解制备偏硼酸钠的反应动力学进行了研究.结果表明,实验条件下硼的溶出符合缩核模型,主要受表面化学反应控制,宏观动力学方程为1-(1-X)1/3=1.3712×102e-31640/(RT)t,活化能为31.64 kJ/mol.升高温度或提高初始NaOH溶液浓度可强化硼的溶出.经两级串联溶出的4次循环实验,在第一级温度140℃、初始NaOH浓度25%(ω)、液固质量比4:1、时间2 h和搅拌速度500 r/min的条件下,第二级温度150℃、其他条件与第一级相同的条件下,各次溶出的硼转化率为86.84%～96.26%,第二级溶出液含硼达27.33～29.84 g/L,Si和Al等杂质维持低浓度.90℃密闭保存陈化脱色的第二级溶出液自然降温至25℃,恒温搅拌结晶6 h(200 r/min),2 h时基本达平衡,粗晶依次用无水乙醇和饱和偏硼酸钠溶液洗涤,40℃干燥12 h,制得截面呈平行四边形或六边形的NaB(OH)4,纯度约90%,结晶率大于70%.Decomposition kinetics of boron concentrate in NaOH-H2O system was studied. The shrinking core model with surface chemical reaction control described the process reasonably well under the experimental conditions. Macrokinetic equation of leaching reaction of boron was 1-（1-X）1/3=1.3712×102e-31640/（RT）t with the activation energy of 31.64 kJ/mol. Increasing temperature or initial concentration of NaOH solution intensified the leaching of boron. The experimental results of two-stage leaching via four cycles indicated that under the conditions of 140℃, initial mass fraction of NaOH 25%, mass ratio of liquid to solid 4：1, reaction time 2 h and stirring speed 500 r/min in the first stage leaching while 150℃ in the second one with other conditions being the same as in the first stage, the conversion rate of boron reached 86.84%～96.26% in each leaching. The concentration of boron in the leachate from the second stage reached 27.33～29.84 g/L while the content of Si and Al kept low. The leachate from the second stage, hermetically preserved at 90℃ until faded, was naturally cooled to 25℃, crystallized isothermally for 6 h（stirring speed of 200 r/min） and nearly reached equilibrium after 2 h. Washed with anhydrous ethanol and saturated NaBO2 solution successively and dried for 12 h at 40℃, NaB（OH）4was obtained, with the purity of almost 90%, crystallization rate of over 70% and sections of parallelogram or hexagon.

关 键 词：硼精矿 两级溶出 冷却结晶 偏硼酸钠 动力学 

分 类 号：TQ128.5[化学工程—无机化工]