摘要
实验研究了难分解铌钽矿在高浓度氢氧化钾溶液中浸出过程的机理。考察了搅拌转速、反应温度、碱矿比、初始氢氧化钾浓度和矿粒度对铌钽矿中铌的浸出速率的影响。结果表明铌的浸出速率与铌钽矿粒径的平方成反比,浸出过程受克-金-布产物层固膜扩散控制,即1+2(1-X)-3(1-X)2/3=kt,并由阿累尼乌斯方程得到铌的表观活化能为72.2kJ﹒mol-1。结合动力学实验结果和电子扫描电镜(SEM)及X-射线能谱(EDAX)分析,进一步证明了在浸出过程中铌钽矿的表面形成了固相产物层,其主要组成元素为铁、锰等,并指出六铌(钽)酸根离子([(Ta,Nb)6O19]8-)通过固相产物层的内扩散为浸出过程的控制步骤。研究结果为浸出过程的强化提供了依据。
The leaching mechanism of niobium from a refractory niobium-tantalum ore by concentrated potassium hydroxide was studied. The effects of stirring speed, reaction temperature, mass ratio of alkali-to-ore, initial potassium hydroxide concentration and particle size on the leaching rate of niobium were reported. The results show that the leaching rate is direct proportional to the inverse square of particle diameter, and the experimental data of the leaching rate are fit to the Crank-Ginsting-Braunshtein’s diffusion-through-layer-reaction-control model,that is: 1+2(1-X)-3(1-X)2/3=kt. According to the Arrhenius expression, the apparent activation energy for the leaching of niobium is 72.2kJ?mol?1. Based upon the result of the kinetic experiment as well as the SEM and EDAX analysis results, it is proved that during the leaching process of niobium-tantalum ore by concentrated potassium hydroxide, a solid product layer is formed on the surface of the unreacted core and its main composition elements are iron and manganese, the diffusion of [(Nb,Ta)6O19]8? through that layer is presumed to be the rate-controlling step of the leaching proces. The results obtained in this paper provide important basis for the strengthening of the leaching process.
出处
《高校化学工程学报》
EI
CAS
CSCD
北大核心
2005年第2期148-155,共8页
Journal of Chemical Engineering of Chinese Universities
基金
国家"十五"863资助项目(2001AA647010)
国家自然科学基金资助项目(20306031)。
关键词
铌钽矿
浸出
高浓氢氧化钾
机理
niobium-tantalum ore
leaching
concentrated potassium hydroxide
mechanism
