石煤钒矿清洁高效氧化提钒及其浸出机理研究

Based on the abundant stone coal vanadium ore resource in Xiangxi area, the complexity of its compose, various valence co-existence in leaching vanadium process, and complicated variety of the physical and chemical changes, this project is designed to realize green efficient and oxidative leaching vanadium and prepare vanadium pentoxide from the stone coal vanadium ore, and study its oxidative leaching mechanism. This project intends to analyse the thermodynamics in the leaching process, study the phase change, decomposition characteristics, electrochemical behavior and valence state transformation law of vanadium in the leaching process, analyse the leaching behavior of the related elements, adjust and optimize the leaching process. According to the kinetics theory of the liquid-solid reaction to handle the experimental data, the digestion kinetics of each element in leaching process is obtained, and the leaching kinetics model is established for several vanadium components with different valences in stone coal vanadium ore. By using the weighted stack method according to the kinetics behavior of the components, the total kinetic equation of leaching vanadium is established and the efficient oxidative leaching mechanism is elucidated for the stone coal vanadium ore, and the causes for high efficient leaching of vanadium are confirmed.We use these to guide to determine efficient technological parameters of leaching vanadium. Meanwhile, the effects of valence state distribution of vanadium in stone coal and the nature of oxidant on the leaching mechanism are analysed. In order to form green efficient utilization chemical metallurgy technology of the stone coal vanadium ore, the oxidant is designed and the valuable elements is recycled that combined with requirements of the green efficient , economical and environmental protection. The research results will provide experimental exploration and theoretical basis for the development and utilization of stone coal in our country.

基于湘西地区丰富的石煤钒矿资源，针对其组成的复杂性、浸出过程钒价态的共存性和物理与化学变化的复杂多样性，本项目旨在从石煤钒矿中，实现钒的清洁高效氧化浸出，制备五氧化二钒产品，并研究其氧化浸出机理。拟对浸出过程进行热力学分析，研究石煤钒矿的物相变化、分解特性、电化学行为及钒的价态转化规律，分析相关元素的浸出行为，以此调整和优化浸出工艺过程。根据液-固浸出反应的动力学理论处理实验数据，得出各元素的溶出动力学，确定石煤矿中几种价态钒组分浸出动力学模型；采用组分动力学行为加权叠加方法，建立石煤矿中钒浸出总动力学方程，阐明石煤钒矿的氧化浸出机理，确定高效浸出钒的原因，以此指导确定高效浸出钒的工艺参数。分析钒的价态分布及氧化剂的性质对浸出机理的影响，结合清洁高效、经济环保要求进行氧化剂设计及有价元素回收，形成石煤钒矿清洁高效提钒的化工冶金工艺技术。研究结果可为石煤钒矿的开发利用提供实验依据和理论基础。

采用硫酸溶液直接浸出法制备+3价态含钒石煤矿样，焙烧-碱浸法制备+4价态含钒石煤矿样，两段焙烧法制备+5价态含钒石煤矿样，通过单因素实验，控制合适的浸出条件和焙烧条件，制备得到各单一价态钒含量大于98%的含钒石煤矿样。筛选出适合石煤原矿和单一价态含钒石煤矿样氧化浸出的氧化剂，考察了氧化剂用量、液固比、硫酸浓度、浸出温度、浸出时间对钒浸出率的影响，并设计正交试验对浸出条件进行了优化，获得了最佳的浸出条件。浸出温度和硫酸用量是钒浸出率大小主要影响因素。. 采用核收缩模型研究石煤原矿和单一价态含钒矿样氧化浸出过程的动力学机理。+3价态矿样氧化浸出过程受固膜扩散控制，表观活化能为63.22kJ/mol，表观反应级数为1.303。+4价态矿样，在35~60℃条件下，浸出过程受化学反应控制，表观活化能为32.32kJ/mol；在65~95℃条件下，浸出过程受固膜扩散控制，表观活化能为49.04kJ/mol。在实验用硫酸浓度范围内，表观反应级数为1.018，当硫酸浓度大于30%时，浸出过程由化学反应控制转化为固膜扩散控制。+5价态含钒矿样直接浸出过程受化学反应控制，表观活化能为28.28kJ/mol，表观反应级数为1.015。石煤钒矿浸出动力学过程与钒的价态分布密切相关：价态越高，浸出活化能越低，被浸出趋势越大，V(Ⅲ)较难浸出，V(Ⅳ)次之，V(Ⅴ)最易浸出，将低价钒氧化为易浸出的高价钒，可有效提高钒浸出率。通过分析石煤钒矿中钒的价态分布，对钒浸出过程的动力学机理进行推断，确定高效浸出钒的原因。. 以钒浸出液为原料，采用沉淀分离法制备得到纯度为99.8%的高纯五氧化二钒。以高纯五氧化二钒为原料，分别采用水热法、高温碳热法和锌粉还原法制备二氧化钒和三氧化二钒，为钒冶炼产品的精深加工、钒氧化物的制备提供了实验依据。. 最后，通过分析钒的价态分布及氧化剂的性质对浸出机理的影响，结合清洁高效、经济环保要求进行氧化剂设计及有价元素回收，形成了石煤钒矿清洁高效提钒技术。研究结果可为石煤钒矿的开发利用提供实验依据和理论基础。