串级萃取状态方程及多元稀土萃取分离工艺设计

本文在Underwood“数群”方法的基础上,讨论了恒定分离系数恒定混合萃取比串级萃取体系中级与级间的“数群”关系;提出了串级萃取状态参数和状态方程的概念;建立了设计多元稀土串级萃取分离工艺的方法。     

稀土串级萃取工艺参数的程序设计

依据串级萃取理论设计了一种计算萃取工艺参数的程序，既省时简便，使用效果又好。     

等效双组分法计算多元稀土串级萃取分离工艺参数

根据多元稀土串级萃取分离体系中组元萃取平衡关系和物料衡算关系,建立了从宏观上描述体系整体的萃取段状态方程和洗涤段状态方程;提出了分布组元、分布组元有效纯度和等效混合萃取比的概念,并将多元稀土串级萃取分离体系描述为以分布组元有效纯度和等效混合萃取比作表征的恒定等效混合萃取比的等效双组分串级萃取分离体系。根据“宏观等效”的原则,提出了计算等效混合萃取比和多元稀土串级萃取分离工艺参数的方法。     

中钇富铕稀土分离工艺的研究

本文介绍了适合于中钇富铕稀土配分特点的分离新工艺和串级萃取方面的经验,重点对新工艺的合理性和先进性进行了论证。     

富铕中钇矿稀土萃取分离新工艺流程的研究

在比较传统工艺的基础上，提出以三出口为主体的富铕中钇矿萃取大分组的工艺及特点。     

串级萃取稀土工艺中流量测控系统的开发

介绍根据生产稀土的串级萃取工艺要求所设计的一套完整的、能够对流量进行自动检测、调节、显示及参数修改的测控系统。     

稀土串级萃取静态递推模型的研究

针对双出口稀土串级萃取分离工艺,建立了两组分静态递推模型。区别于代数模型,首先将萃取过程归结为初始萃取段、置换萃取段、进料级、置换洗涤段、初始洗涤段5种类型,然后建立了各个对象、及对象间的交互关系。利用对象之间的调用和迭代,模型求解速度快于其他模型。分析了萃取液和洗涤液流量波动对稀土产品出口纯度影响的规律,确定了检测点的最佳位置。     

多组分稀土串级萃取有效分离系数的研究

提出了计算多组分稀土串级萃取有效分离系数的平均分数法,研究了稀土摩尔分数对有效分离系数的影响,比较了等效组分法、数学模型法、产品分数法和平均分数法的计算结果.研究表明,仅有平均分数法计算的有效分离系数均介于最大值和最小值之间,而且其极值均与理论极值相等.平均分数法具有更宽的适应范围和更高的准确度.     

Advances in Rare Earths Separation and Purification

The conventional method of separation of rare earths by multistage liquid-liquid extraction is still the best processing technology for their separation and purification. One of the most promising developments in the last decade that could have an impact on the rare earths separation technology is the synthesis of mucrocyclic ligands that have a high degree of selectivity in their complexation. Trivalent lanthanides have recently been transported across liquid membranes containing macrocycic ligands. The use of facilitated liquid membranes reactors in the concentration of very dilute rare eaith streams can be very effective in terms of recovery as well as environmental considerations. The electroreduction of E³⁺ to E²⁺ and the electroodixation of Ce³⁺ to Ce⁴⁺ are potential replacements for chemical reaction valence change methods. The electrolytic method eliminates the introduction of other chemical reagents that need to be treated downstream to satisfy environmental codes. Improvements in the design and control of mixer-settlers and other liquid-liquid extraction equipment will result in higher stage efficiency.     

Separation of Rare Earths by Solvent Extraction

Abstract

Solvent extraction technology for the separation of rare earths is a recent one. This is mainly due to the low separation factors between the adjacent rare earths for any type of extractants that have been investigated so far. In spite of this inherent weakness arising due to the gradual small changes in basicity in the series of rare earths few extractants have been used on commercial scale for the separation of high purity rare earths. In this paper the mechanisms involved in the extraction of rare earths using different types of extractants like tributylphosphate, di (2-ethylhexyl) phosphoric acid, 2-ethylhexyl 2-ethylhexyl phosphonic acid and quaternary ammonium salts have been discussed. The development of suitable mathematical models of the extraction behaviour of rare earths, particularly for the liquid cation exchangers, and their suitability for the development of the processes for the separation of rare earths is highlighted. Various process parameters that have been optimised using the computer programs developed by incorporating the mathematical models have been used in the purification of rare earths. The flow sheets designed for the separation of various rare earths are also given.     

从废稀土荧光粉中酸浸回收稀土的研究

从稀土荧光灯生产工艺过程产生的废稀土荧光粉中酸浸出稀土的实验结果表明,酸浸出法能够浸出废稀土荧光粉中的稀土。与用盐酸和硝酸浸出相比,用硫酸浸出废稀土荧光粉中稀土的浸出率较高,从技术、经济及环保角度考虑,优选用硫酸作为从废稀土荧光粉中浸出回收稀土的浸出剂。提高浸出反应温度、增加硫酸浓度和提升浸出器转速,都能提高稀土的浸出率。在温度45℃条件下,用2 mol.L-1硫酸浸出工艺废稀土荧光粉8 h,4种稀土Y,Eu,Ce,Tb的浸出率分别为67.9%,73.1%,66.4%,67.9%,非稀土成分Al的浸出率为39.2%。当升高温度到接近100℃进行硫酸浸出时,4种稀土Y,Eu,Ce,Tb的浸出率分别上升到80.4%,82.2%,81.4%,80.0%,非稀土成分Al的浸出率则增高到86.1%。扫描电镜图像显示废稀土荧光粉浸出前表面较平整,而其浸出渣的表面则有微小的絮状物和粒度变细,表明硫酸浸蚀废荧光粉而使稀土进入溶液中。浸出前后能谱分析显示,废稀土荧光粉浸出渣中稀土的相对含量已大大降低,表明稀土大部分已被硫酸浸出,浸出渣中的不溶物主要是C。     

Mathematical Modelling of the Liquid-Liquid Extraction Separation of Rare Earths

Abstract

An empirical mathematical model has been developed for the simulation of an integrated solvent extraction circuit consisting of an extractor, scrubber and a stripper. This model is designed to simulate the separation of any lanthanide from a mixed lanthanide feed. The Kremser equation is used to calculate the separation occurring in each section of the circuit. The inputs required for the simulation are the feed composition, separation factors, equilibrium data of the key element under a wide range of conditions, the number of stages and flow rates of the aqueous and organic streams in the circuit. This model has been validated with the experimental data for the separation of Nd from a mixed lanthanide chloride feed with 2-ethylhexyl phosphonic acid mono 2-ethyl-hexyl ester (EHPNA) as an extractant.     

Liquid-Liquid Extraction Processes for the Separation and Purification of Rare Earths

A review of the literature on liquid-liquid extraction processes for the separation and purification of rare earths is presented. This review also discusses computer simulation programs used for the design and optimization of processes for the separation of rare earths. The lacunae in the computer simulation programs are highlighted and suggestions for future work are given.     

织金磷矿酸浸液萃取分离稀土试验研究

研究了用溶剂萃取法从织金磷矿酸浸液中分离稀土,考察了各因素对稀土萃取率和反萃取率的影响,确定了适宜的萃取条件。结果表明:用P204作萃取剂,控制相比为3∶1、P204浓度为1.5 mol/L、初始水相P2O5质量浓度为101.20g/L、在室温下萃取15min,稀土萃取率为89.62%;在相比1∶8、6mol/L盐酸为反萃取剂、室温下反萃取10min条件下,稀土反萃取率为87.86%。     

Separation of Scandium and Rare Earths with the Method of PSO-Extraction Chromatography

Separation of scandium and rare earths was investigated by using a new extraction chromatography whichPSO was used as a stationary phase,while HCl-NH_4SCN solution as a mobile phase.The separation conditionswere studied.In this system, the separation factor(β_(Nd)~(Sc))can reach up to 1.3×10~4.The method can be applied tothe purposes of separation,purification and analysis of microquantity of Sc in the mixed rare earth.     

从伴生稀土磷矿中回收稀土的研究进展

介绍了国内外伴生稀土磷矿概况,综述了磷化工过程中回收稀土的方法及研究现状,展望了未来湿法磷酸生产过程中微量稀土元素的提取研究方向。