风化壳淋积型稀土矿堆浸提取稀土过程动力学

Weathered crust elution-deposited rare earth ore is our precious and unique mineral resources, more and more attention was paid on its exploitation. Forty percent of the rare earth ore must be exploited by heap leaching technology instead of in-situ leaching technology for the different reasons of the formation ore. However, the investigation about the leaching hydrodynamics and kinetics had rarely reported. The lack of the guidance of the basic theory induced the low leaching rate of rare earth when using the heap leaching technology, resulting in the limitation of the usage of this technology. The weathered crust elution-deposited rare earth ore, which could not be exploited by in-situ leaching technology, is our investigation object in this project. The mechanism of seepage flow in heap leaching process was studied by use of micro-diffusion model and macro-Seepage model. The kinetic model was set up by investigation of the leaching kinetic and hydrodynamics process. The key factors in heap leaching were discussed, and evaluation system for heap leaching of weathered crust elution-deposited rare earth ore was found to optimize the process parameters and increase the leaching rate of the rare earth ions. The investigation in this project would provide the theoretical basis and scientific method for giant heap leaching, and would enrich rare earth hydrometallurgy and elemental chemical theory.

风化壳淋积型稀土矿是我国特有的矿产资源，其开发利用具有举足轻重的地位。由于矿山成矿原因的差别，约40%左右的风化壳淋积型稀土矿不能采用原地浸出工艺，而必须采用堆浸工艺进行开采。然而目前堆浸工艺基础研究不够，关于堆浸的浸出动力学和水动力学研究很少，无法指导堆浸工艺的生产实践，造成了堆浸工艺稀土回收率偏低，从而限制了堆浸工艺的推广。为此，本项目针对不适合于采用原地浸出工艺开采的风化壳淋积型稀土矿，利用微观渗透扩散模型和宏观渗流模型，研究堆浸过程的渗流机理；通过对风化壳淋积型稀土矿堆浸过程动力学和水力学研究，建立风化壳淋积型稀土矿堆浸动力学模型和水动力学模型；探讨影响堆浸工艺的关键因素，创立风化壳淋积型稀土矿堆浸的评价体系，优化堆浸工艺，达到高效浸取稀土。为开发巨型堆堆浸提供理论基础，为风化壳淋积型稀土矿稀土的高效回收提供理论依据，丰富稀土湿法冶金和稀土元素化学理论。

风化壳淋积型稀土矿的高效开发利用一直是研究热点。因成矿原因的差别，约40%左右的风化壳淋积型稀土矿不能采用原地浸出工艺，而必须采用堆浸工艺进行开采。然而目前堆浸工艺基础研究不够，关于堆浸的浸出动力学和水动力学研究很少，无法指导堆浸工艺的生产实践，造成了堆浸工艺稀土回收率偏低，从而限制了堆浸工艺的推广。为此，本项目以广东大浦五丰稀土矿为研究矿点，研究其矿床矿石特性，利用微观渗透扩散模型和宏观渗流模型，研究堆浸过程的渗流机理、稀土矿堆浸动力学、水力学和浸出传质效率，优化堆浸工艺，取得的主要成果如下：.稀土矿床矿石特性研究发现，矿区内矿床平均厚度6.89 m，平均品位0.093%；矿石的矿物组成主要为黏土（20-70%）、钾长石（5-53%）、石英（20-26%）及少量黑云母（3%），微量矿物有磁铁矿（2%）等；含轻稀土54.24~86.34%，为轻稀土配分型稀土矿；矿石含SiO2最多为70.52%，其次是Al2O3为16.61%，其余矿物含量较少。.考察了各浸取因素对稀土浸出的影响，发现适度增大浸取剂浓度或浸取温度均能提高稀土的浸出率和浸取传质效率。三种铵盐浸取稀土的传质效率大小为硫酸铵<氯化铵<硝酸铵，说明稀土与阴离子之间的螯合能力为SO42- <Cl－< NO3-。.考察了稀土和铝的浸出动力学过程，结果表明稀土和铝的浸取过程受内扩散动力学控制，浸取反应活化能均为4~12 kJ/mol。建立了关于温度和浓度的内扩散动力学方程，发现铝的浸取表观速率小于稀土，表观速率越大，浸出速度越快；稀土的浸取活化能和反应级数小于铝，浸取活化能越小，浸出速度越快，而反应级数越小，浓度对其影响越小。.考察了各因素对浸取剂在矿堆中渗透过程的影响，发现浸取剂在矿堆中的渗流符合达西定律，且处于层流状态。浸取剂浓度越小，浸取温度越高，液体黏度越小，渗透速度越大，且温度对渗透性的影响大于浓度；矿石颗粒越小，孔隙度越小，渗透性就越差，且矿石粒径对渗透性的影响大于孔隙度。