选择性氧化还原从荧光粉废料中回收稀土的基础研究

Rare earth phosphor is widely used in many fields such as information display,illumination and optoelectronic devices.With the increasing popularization of energy saving lamps and usage amount of phosphor, phosphor sludge springs up accordingly. Rare earth is the extremely important strategic material. In the situation of enhancing conservation and comprehensive utilization of rare earth, implementing mandatory planning management,and sustainedly stably growing of market application demand. It is significant to recover rare earth from phosphor sludge. According to technnique has drawbacks of low separation and recovery of rare earth elements, complicated craftwork, etc.The project takes method of selective oxidation and reduction. In order to clear process and reaction mechanism, kinetics and thermodynamics, the project studies recovering rare earth from phosphor sludge by selective oxidation and reduction, including the following base studies: oxidation roast phosphor sludge to be the phase reconstruction of thermodynamics and occurrence state,leaching kinetics of calcined products, non rare earth impurities behavior of the leaching solution and removal mechanism, the important technical parameters of extraction equilibrium under different system in the process of extraction and separation of rare earth, separation characteristics research and so on. The project aims to provide theoretical and technical guidance to using selective oxidation and reduction to recover rare earth from phosphor sludge.

稀土荧光粉广泛用于信息显示、照明光源、光电器件等领域。随着节能灯的日益推广和普及，各类荧光粉用量不断增加，与之相应的荧光粉废料也就不断涌现。稀土是极为重要的战略物质，在当前我国加强稀土资源保护和综合利用，国家对稀土产品实行指令性计划管理和市场应用需求持续稳定增长形势下，从含稀土的荧光粉废料中回收稀土具有特别重要意义。针对现有处理荧光粉废料稀土技术存在回收率低、工艺复杂等缺点，我们采用选择性氧化还原法回收稀土，为明晰过程作用机理和反应的热力学、动力学等，本项目对选择性氧化还原法从荧光粉废料中回收稀土的基础进行研究，包括荧光粉废料氧化焙烧进行物相重构热力学及赋存状态，焙烧产物浸取动力学，浸出液非稀土杂质行为与去除机制，稀土萃取分离过程中不同体系下萃取平衡的重要技术参数（如分配比、分离系数等）和分离特性研究等。旨在对选择性氧化还原法从荧光粉废料回收稀土提供理论和技术指导。

稀土是极为重要的战略物质，在当前我国加强稀土资源保护和综合利用的形势下，从含稀土的荧光粉废料中回收稀土具有特别重要意义。本项目针对现有处理荧光粉废料稀土技术存在回收率低、工艺复杂等缺点，采用选择性氧化还原法对荧光粉废料中回收稀土的基础进行研究，包括直接焙烧-酸浸-环烷酸萃取与一次酸浸-水洗-焙烧-二次酸浸-环烷酸萃取工艺，研究结果表明：NaOH作为焙烧助剂有利于荧光粉废料的重构，通过稀土元素尤其是铈、铽等变价元素及铝、镁、磷等在焙烧过程中相变规律，探明碱焙烧作用机理，分析了各元素在焙烧、浸出时的热力学行为，绘制了稀土浸出过程的电位-pH图，探明了助溶剂H2O2强化浸出机理和浸出后液非稀土杂质去除机制，建立了荧光粉废料浸出动力学模型，确定的较优工艺条件主要为，焙烧温度850℃左右，焙烧时间90-120min，氢氧化钠添加量为Na2O与荧光粉废料中Al2O3苛性比2.0:1，酸浸H2O2添加量10%，盐酸浓度3 mol/L，浸出温度80℃，浸出时间60 min，稀土总浸出率达99.32%，考察了温度、相比、料液初始浓度等因素对遴选出的环烷酸除杂与萃取分离性能，根据串级萃取模拟计算，获得分离稀土的最优技术参数。本项目的研究成果对选择性氧化还原法从荧光粉废料中回收稀土提供了理论和技术指导。