稀土电解熔盐渣焙烧产物酸浸提取稀土、锂和氟

稀土电解熔盐渣经过氧化钙和硫酸铝协同焙烧活化得到焙烧渣,采用硫酸浸出高效提取焙烧渣中稀土、锂、氟,系统考察了不同酸浸条件对稀土、锂、氟浸出率的影响。针对较优酸浸条件下的浸出液,用硫酸钠沉淀析出稀土复盐沉淀,实现稀土分离。结果表明:较优酸浸条件为硫酸浓度4 mol/L、液固体积质量比10:1（单位:mL/g）、浸出温度90 ℃、浸出时间4 h,熔盐渣中镨、钕、钆、锂、氟的浸出率分别为95.83%、96.55%、93.06%、95.52%、94.85%。稀土复盐沉淀纯度高,稀土回收率达99.3%以上。该方法可以高效回收稀土熔盐电解渣中稀土、锂、氟有价元素,对提升稀土熔盐电解渣的全组分利用具有重要意义。      

稀土熔盐渣中有价金属综合回收技术研究现状及进展

中国是稀土生产大国,在每年的工业生产中都会产生大量的稀土固废,其中熔盐电解法制备稀土金属过程中产生的熔盐电解冶炼渣成分复杂、稀土含量较高(20%～80%,以稀土氧化物计)。结合国家稀土资源的可持续发展战略,本文针对稀土熔盐渣中稀土元素等有价金属的综合回收方法进行了综述总结,包括酸浸回收法、碱转酸浸法、盐转焙烧法等工艺,分析对比了各回收工艺的原理、特点和优劣,总结概述了各工艺综合回收稀土等有价金属时的最佳条件,为后续探究高效回收稀土等有价金属的工艺、解决稀土资源短缺问题提供了参考与技术支持。     

稀土电解废熔盐的综合利用研究

主要研究了从氟化体系熔盐电解过程产生的废熔盐回收合格熔盐和氧化稀土的工艺条件；采用本工艺得到的熔盐可直接返回电解生产线使用，制取的氧化稀土质量都达到国家标准，稀土总收率达90．09％。     

熔盐电解渣磁选-焙烧-浸出提取稀土元素

以稀土熔盐电解渣为原料,提出了磁选—焙烧—浸出工艺提取稀土元素。全过程工艺考察结果表明,原料在100 mT的最佳磁场强度条件下,除铁率达到45.59%,非磁性相在焙烧浸出过程的最佳工艺条件为：焙烧温度750 ℃、CaO添加量30%、浸出温度25 ℃、盐酸浓度3 mol/L,全过程工艺的Nd、Pr的总回收率分别达到95.98%、96.15%。采用原位XRD表征结合热力学分析,明晰了焙烧过程矿相转化规律,发现在焙烧过程中REF3与CaO反应生成REO,同时CaCl2与CaO、REF3先生成REOCl,REOCl再进一步转化为REO,提高焙烧温度能够减少难溶物相REOCl的生成,促进REF3向易溶物相REO的转变,进而提高稀土浸出率。本研究可为稀土回收提供理论指导。     

从蒸馏渣中回收稀土工艺研究

以稀土电解熔盐渣经矿相重构—真空蒸馏处理后的蒸馏渣为原料,采用盐酸酸浸提取蒸馏渣中的稀土,研究了酸浸时间、酸浸温度、盐酸浓度、液固比(L/S)对稀土和铁浸出率的影响。结果表明,在酸浸温度50℃、盐酸浓度4mol/L、酸浸时间1h、液固比4的较优工艺条件下,稀土浸出率高达99.88%,铁浸出率为44.43%,达到了稀土优先溶出的目的。     

磷酸浸出渣中提取稀土的研究

以湿法磷酸工艺中产生的非石膏类伴生稀土渣为原料、硫酸为浸出剂,考察硫酸浓度、反应温度和时间、液固比等对稀土浸出率的影响。结果表明,在下述综合试验条件下稀土浸出率可以达到81.9%:硫酸浓度14%、温度90℃、液固比4∶1、反应时间2h,硫酸浸出渣主要由石英、针状石膏和柱状石膏晶体组成。     

熔盐电解制备稀土铝合金的研究

铝中加入一定量的稀土金属后,铝合金的导电性、机械强度、耐腐蚀性和耐热性等方面都有明显的提高。稀土金属在铝合金中具有净化、细化和合金化效果。稀土铝合金因有上述的特点,而广泛地应用在电工铝的生产上。研究稀土铝合金的制取方法对稀土铝合金的广泛应用具有积极的推动作用。本实验使用熔盐电解法制备了稀土铝合金。     

稀土熔盐电解智能控制系统研究与应用

针对目前稀土熔盐电解工艺自动化水平较低,本文提出研究稀土熔盐电解智能控制系统。构建智能控制系统的总体框架,研究智能控制系统的关键技术,提出采用模糊自适应PID控制算法协调控制加料量和电解电源,实现对电解槽熔盐温度的实时调整。研究的智能控制系统在6 kA熔盐电解槽进行了实验,实验结果表明,该智能控制系统能够自适应调整电解槽熔盐温度,使得温度偏差在±0.9%范围内,且系统性能稳定,实用性强,为实现稀土熔盐电解工艺的智能化管理提供一定的技术指导。     

电流密度对稀土熔盐电解影响的探讨

分析探讨了阳极电流密度、阴极电流密度以及体电流密度对稀土氟化物体系熔盐电解槽运行效果的影响，确定了合理的电解槽电流密度参数范围。     

稀土熔盐电解中非碳阳极的研究

针对稀土金属钕的熔盐电解,研制了一种适合于氟化物—氧化物体系的非碳阳极,这种电极既具有传统的碳阳极的全部优点,同时又能克服碳阳极的不足,消除产品中合碳量过高的现象,这种非碳阳极材料具有较好的高温导电性,较低的显气孔率,另外,其抗高温熔盐腐蚀性较好,是一种较理想的稀土熔盐电解电极材料。     

基于Comsol的稀土熔盐电解槽电场分析

采用Comsol Multiphysics 有限元软件,基于麦克斯韦原理,在电流不变的情况下,研究建立3 kA稀土钕熔盐电解槽电场数学模型,考察电极插入深度和极距对槽电压、电流密度等电场特征的影响。结果表明,模拟结果与实际生产数据吻合度高,所建立模型能较好地反映钕熔盐电解生产实际;随着电极插入深度的增大和极距的缩短,电解槽电压下降,利于降低电能消耗,但阴极电流密度比阳极电流密度下降快,不利于电流效率提高。应综合考虑能耗和效率,合理调整电极插入深度和极距,以降低钕熔盐电解单位能耗。     

Non-ammonia enrichment of rare earth by magnesium oxide from rare earth leaching liquor in magnesium salt system

In order to solve the problem of ammonia-nitrogen pollution in the enrichment process of the ionadsorption type rare earth ore,the technology of non-ammonia precipitation with magnesium oxide precipitant was carried out.It is determined that the rare earth precipitation efficiency is 99.6% and the purity of rare earth concentrates is only 85.89 wt%under the optimum precipitation conditions.And the contents of MgO,SO_3 and Al_2O_3 in the rare earth concentrates are 5.12 wt%,6.77 wt%and 1.78 wt%,respectively.Furthermore,the thermo-decomposition process of precipitates was investigated by TGDSC,XRD and FI-IR.The thermal decomposition process consists of two stages:the dehydration of rare earth hydroxide and alkaline rare earth sulfate within 900 ℃ and the thermal decomposition of RE_2O_2SO_4 at 900-1300 ℃.Therefore,a high-temperature calcinations method for removing SO_3 from precipitates is proposed.When the precipitates are calcined at 1300 ℃ for 2 h,the rare earth concentrates with a purity of 92.03 wt%can be acquired.Moreover,the content of SO_3 in the concentrate is only 0.46 wt%.In the MgO precipitation and high-temperature calcinations process,the raw material cost is low and the quality of rare earth concentrates is acceptable.It could have great significance for nonammonia enrichment of rare earth from the rare earth leaching liquor,and finally solve the problem of ammonia nitrogen in the extraction process of the ion-adsorption type rare earth ore within magnesium salt system.     

还原酸浸对废旧稀土荧光粉中稀土提取的影响

为解决废旧稀土荧光粉中高价态Ce、Tb氧化物浸出困难的难题, 在碱熔焙烧预处理的研究基础上, 采用还原酸浸的方法, 以抗坏血酸作为还原剂, 来提高废旧稀土荧光粉的稀土浸出率。实验表明:在HCl浓度为4 mol/L, HCl与水洗渣液固比(单位为:mL/g, 下同)为10:1、抗坏血酸用量为10%、温度为338 K、时间为120 min、搅拌转速为650 r/min的条件下, 稀土浸出率可以达到98%以上。      

Effect of roasting activation of rare earth molten salt slag on extraction of rare earth,lithium and fluorine

A new process was proposed to extract rare earth elements(REEs),Li and F from electrolytic slag of rare earth molten salt by synergistic roasting and acid leaching.Firstly,the thermodynamic analysis of roasting reaction was carried out,then the effects of roasting factors on leaching REEs,Li and F in slag were investigated.In additions,the mineral phase and morphology of molten salt slag,roasting slag and acid leaching slag were characterized,and the migration mechanism of REES,Li and F minerals...     

硫酸浸出磷石膏中稀土的动力学研究

针对磷石膏中稀土元素的浸出,已有很多研究报道,但对于浸出动力学研究却很少。文章以硫酸为浸取剂深入研究了磷石膏中稀土浸出的动力学。研究表明:浸出温度和时间的增加均可提高稀土的浸出率,浸出温度80 ℃时,稀土总浸出率最大可达55.8%,其中Y的浸出率最大,为63.9%;稀土的浸出与二水硫酸钙的溶解具有很强的线性相关性;动力学模型拟合表明:磷石膏中稀土浸出反应是受扩散和界面传质混合控制的,浸出反应的表观活化能E_a=9.10 kJ/mol。      

Rare earth recovery from fluoride molten-salt electrolytic slag by sodium carbonate roasting-hydrochloric acid leaching

Fluorinated rare earth molten-salt electrolytic slag contains a considerable amount of rare earth elements,as well as a variety of heavy metals and fluorides that cause environmental pollution.Therefore,it is of great importance to fully utilise this resource.In this study,the transformation mechanism of fluorinated rare earth molten-salt electrolytic slag roasted with sodium carbonate,and the regulation mechanism of rare earth leaching under different roasting conditions were investigated with ...     

铁闪锌矿在硫酸浸出过程中的电化学行为

为研究铁闪锌矿氧化浸出机理,以人工合成铁闪锌矿的悬浮矿浆为研究对象,采用三电极体系对其在硫酸浸出过程中的电化学行为进行了研究.结果表明在铁闪锌矿浸出过程中有H₂S中间产物生成;通氧、元素硫分散剂以及氯离子引入浸出体系均能明显促进铁闪锌矿的电化学氧化;随硫酸浓度升高,铁闪锌矿的电化学氧化不断加强而闪锌矿的电化学氧化受抑.与闪锌矿相比,铁闪锌矿更易发生电化学氧化.在铁闪锌矿硫酸浸出过程中,其电化学氧化作用不容忽视.     

含金硫酸渣硫酸盐化焙烧—氯盐浸出试验研究

针对难处理含金硫酸渣进行了硫酸盐化焙烧—氯盐浸出试验研究,考察了硫酸体积分数、硫酸用量、焙烧温度、焙烧时间、焙烧促进剂用量对焙烧效果的影响,以及氯酸钠用量、氯化钠用量、浸出温度、液固比、浸出时间对浸出效果的影响。试验结果表明:在硫酸用量为1.6 t/t渣,硫酸溶液体积分数为60%,焙烧温度为500℃,焙烧添加剂RS-1用量为50 kg/t,焙烧时间为80 min时,焙烧效果最好;在NaClO_3用量为100 kg/t,Na Cl用量为70 kg/t,浸出温度为80℃,液固比为3.5∶1,浸出时间为3 h时,浸出效果最佳;其最终试验得到浸渣中金品位为1.80 g/t,浸出率为95.01%。     

Extraction and back-extraction behaviors of 14 rare earth elements from sulfuric acid medium by TODGA

The unique physical and chemical properties of rare earth elements lay the foundation for their extensive application. N,N,N',N' Tetra-octyl-3-oxopentanediamide(TODGA) is excellent in its ability of extracting rare earth elements and it is favored for green initiative. In this paper, the extraction and back-extraction of14 rare earth elements by TODGA were studied. Experiments show that in conditions of 6 mol/L sulfuric acid, the extraction temperature of 25 ℃,the phase ratio of 1:1 and 0.04 mol/LTODGA(aviation kerosene as the diluent), the extraction rates of 14 rare earth elements including lanthanum, cerium, praseodymium,neodymium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, and yttrium were 99.00%-99.73%. Mixed with hydrochloric acid and nitric acid(HCl 3.5 mol/L, HNO_30.5 mol/L), the recoveries of the 14 rare earth elements are 91.52%-99.91% when the extraction temperature is 25 ℃ and the ratio is 1:1. The following application is based on the optimum conditions above with practical samples(from the roasting production line of China North Rare Earth High-tech Company Limited) for extraction and back-extraction experiments. Experiments show that TODGA has excellent enrichment effect on 14 rare earth elements, the extraction rates are 91.36%-99.80%, the back-extraction rates are 87.29%-99.64% and the total recoveries are 81.19%-99.44%.