Purification of rare earth elements from monazite sulphuric acid leach liquor and the production of high-purity ceric oxide

The present work describes the development of an efficient and relatively simple process to obtain high grade CeO₂ from sulphuric acid leach liquor. The liquor was obtained through acid digestion of monazite. The steps investigated in the process for obtaining ceric oxide were: (i) purification of the RE elements through their precipitation as rare earth and sodium double sulphate (NaRE(SO₄)₂·xH₂O), (ii) NaRE(SO₄)₂·xH₂O conversion into RE-hydroxide (RE(OH)₃) through metathetic reaction and (iii) recovery of cerium and (iv) purification of cerium from the mixture of ceric hydroxide and manganese dioxide precipitate through dissolution of the solid with HCl and precipitation of the cerium through the addition of oxalic acid (H₂C₂O₄) or ammonium hydroxide (NH₄OH) solution. The X-ray diffraction spectra of the double sulphate obtained indicated the presence of monohydrated double sulphate. X-ray diffraction and chemical analysis indicated that the precipitation should be carried out at 70 °C and at 1.1 times the stoichiometric ratio of NaOH. An excess of 30% of KMnO₄ was necessary to separate cerium from the other RE elements. Both oxalic acid and ammonium hydroxide proved efficient in the precipitation of cerium from the mixture of Ce/Mn obtained in the cerium separation. Following purification, calcinated products were obtained, assaying between 99% and 99.5% CeO₂. The cerium recovery yield was greater than 98%.     

富含独居石稀土矿石中稀土元素测试的前处理方法比较

针对富含独居石稀土矿的样品,本文探讨了敞开酸溶HCl-HNO3-HF-HClO4、HCl-HNO3-HF-HClO4-H2SO4和密闭酸溶HF-HNO3、HF-HNO3-H2O2以及Na2CO3-Na2O2碱熔等5种不同前处理方法,通过电感耦合等离子体发射光谱法、电感耦合等离子体质谱法测定15种稀土元素.结果 表明,HF-HNO3-H2O2密闭酸溶法操作简单,灵敏度高,重现性好,能够替代传统碱熔法.     

Study on separation of heavy rare earth elements by solvent extraction with organophosphorus acids and amine reagents

The present work describes a study of the separation of rare earth elements (REE) from heavy REE concentrate through solvent extraction. Seven extractants were investigated: three organophosphorus acids (DEHPA, IONQUEST^®801 and CYANEX^®272), a mixture of DEHPA/TOPO (neutral ester) and three amines (ALAMINE^®336, ALIQUAT^®336 and PRIMENE^®JM-T). The organophosphorus extractants were investigated in hydrochloric and sulphuric media whereas the amines performance was assessed in a sulphuric medium. The variables investigated were: concentration of the extractant agent, aqueous phase acidity, aqueous/organic volumetric ratio, contact time, stripping agent concentration (hydrochloric acid solution) and the selective stripping step. In the extraction step, the best separation factors for the adjacent elements were obtained with DEHPA and IONQUEST 801. For 1.0 mol L⁻¹ DEHPA in an initial acidity of 0.3 mol L⁻¹ H⁺, the separation factor was 2.5 Tb/Dy, 2.1 Dy/Ho, 1.9 Ho/Er, 2.0 Ho/Y and 1.1 Y/Er; for 1 mol L⁻¹ IONQUEST 801 in 0.3 mol L⁻¹ of H⁺ it was 2.7 Tb/Dy, 2.4 Dy/Ho, 2.1 Ho/Er, 2.1 Ho/Y e 1.5 Y/Er. The study concluded that for the extractants investigated, IONQUEST 801 is the most indicated for the separation of heavy REE because it has lower affinity with the REE compared to the affinity of DEPHA/REE, which makes the strip of the REE from Ionquest 801 easier than from DEHPA. Moreover, the number of stages necessary for the stripping of the REE from IONQUEST 801 is much lower than that observed when DEPHA is employed.     

Process development to recover rare earth metals from monazite mineral: A review

The escalating demand of rare earth metals (REMs) in various applications and their continuous depleting ores have laid emphasis to produce metals from their complex resources by developing energy efficient and eco-friendly processes. Present review reports the commercial processes based on pyro–hydro or hybrid techniques as well as systematic research for process development to recover rare earth from monazite. The salient findings on mining and physical beneficiation of different beach sand deposits containing monazite are reviewed. Monazite concentrate obtained are processed under different condition of time, temperature and concentration using acidic or alkaline solution. They are usually processed using thermal treatment followed by REMs recovery under optimized conditions of leaching and their extraction via solvent extraction, precipitation, etc. to produce salts/concentrate of REMs from the leached solution. The processes developed to recover REMs are reviewed and recommendations are made in respect to various methodologies and objectives.     

由低浓度稀土溶液萃取回收稀土的研究

我国重庆某煤系高硫稀有金属复合矿中含硫(铁)、铝、稀土等多种有价成分,且部分稀土呈离子吸附形态存在。对该矿铵盐浸出液除铝、铁杂质后得到的低浓度稀土溶液,进行了稀土的萃取、反萃取、制备碳酸稀土试验的研究。确定的工艺条件为:有机相组成10%P507+90%260~#磺化煤油、净化液初始pH值为5.5、相比(O/A)0.6、搅拌时间5 min。单级萃取,稀土萃取率为92.79%,两级逆流萃取,稀土萃取率可达99.07%;负载有机相采以稀硫酸三级逆流反萃,稀土反萃率为97.20%,反萃液中TREO可富集至2175 mg/L;稀土与钙、镁等杂质得到了有效分离;反萃液经除锌后,与碳酸氢铵反应,制得的碳酸稀土产品质量符合要求;从净化液到产品,稀土回收率达87.85%;萃余液和碳酸稀土合成母液经处理后可用于循环浸出煤系高硫稀有金属复合矿。     

Bioleaching of trace elements and rare earth elements from coal fly ash

International Journal of Coal Science & Technology - Coal fly ash originated from coal combustion has high concentrations of metals. If suitable leaching techniques are identified, then coal...     

含钒废弃物中钒的回收研究现状及展望

这是一篇冶金工程领域的论文。钒是我国稀缺战略金属资源,应用于众多领域,与国民经济密切相关。现如今提钒工艺综合利用价值越来越大,其中溶剂萃取法提钒受到广泛的关注,它具备选择性强,产品纯度高等优点。对此,文章综述了焙烧、浸出、净化富集和沉钒技术工艺,对溶剂萃取法分离钒的研究工作及方法进行了总结,并重点探讨了叔胺萃取剂对钒的提取及其国内外发展的现状。     

Development of a process for the separation of zinc and copper from sulfuric liquor obtained from the leaching of an industrial residue by solvent extraction

This paper describes a study of the separation of zinc and copper from the leach liquor generated in the treatment of the zinc residue (29.6 g/L Zn and 37.4 g/L Cu) by liquid–liquid extraction. In it, the influence of the extractant type and concentration, aqueous phase acidity, contact time and stripping agent concentration were investigated. Organophosphorus extractants (D2EHPA, IONQUEST®801 and CYANEX®272) and the chelating extractants (LIX®63, LIX®984N and LIX®612N-LV) were also investigated. The organophosphorus reagents are selective for zinc, while the chelating extractants are selective for copper. In the experiment, D2EHPA was found to be the best extractant. A sulfuric acid solution was used in the stripping study. Five continuous experiments were carried out until an optimal condition for the separation of the metals Zn and Cu was achieved. Experiment 5 was carried out in three extraction steps, three scrubbing stages and five stripping stages. In this experiment, a pregnant strip solution containing 125 g/L Zn and 0.01 g/L Cu was obtained and the concentration of the metals in the raffinate was 28.3 g/L Cu and 0.49 g/L Zn.     

Stripping conditions to prevent the accumulation of rare earth elements and iron on the organic phase in the solvent extraction circuit at Skorpion Zinc

The concentrations of the rare earth elements (particularly Y, Yb, Er and Sc) in the zinc-stripped organic phase streams in the solvent extraction process at Skorpion Zinc mine have increased gradually over the past four years. Iron is the only other impurity present in notable quantities in the organic phase after washing and scrubbing prior to zinc stripping. This project aimed to evaluate the effects that rare earth elements and iron in the organic phase have on the zinc solvent extraction process and to subsequently find appropriate stripping conditions for the removal of these elements from the zinc-stripped organic phase.Results obtained by performing laboratory scale batch tests indicated that the viscosity of the organic phase doubled and the phase disengagement time increased from 100 s to 700 s when the total rare earth elements and iron concentration in the organic phase was increased from 3100 mg/L to 6350 mg/L. The zinc loading capacity of the organic phase after two extractions furthermore decreased by a value between 1 g/L and 3 g/L, depending on the composition of the pregnant leach solution. The stripping of low concentrations of rare earth elements and iron from 40% di-2-ethylhexyl phosphoric acid (D2EHPA) diluted in kerosene was evaluated using two different stripping agents (H₂SO₄ and HCl) with concentrations between 1 M and 7 M, organic-to-aqueous ratios between 0.5 and 4, and temperatures between 30 °C and 50 °C. The highest stripping percentages were achieved at acid concentrations greater than 5 M, organic-to-aqueous ratios of less than 0.5 and high temperatures.     

稀土元素在水体除氟中的应用及进展

水环境中的氟污染已被认为是全球严重威胁人类健康的主要问题之一,吸附法被认为是最具有发展前景的水体除氟技术,各国学者也在研发吸附性强和环境友好的新型吸附剂。对稀土化合物和负载稀土元素的吸附剂在除氟中的应用进行了总结,发现稀土化合物的吸附氟能力强,多金属氧化物、生物材料、金属有机骨架和硅基材料等经负载稀土元素改性后制备的新型吸附剂也表现出良好的除氟能力;不同材料和官能团的协同作用可以有效提高吸附剂的除氟能力。在总结现有除氟剂的基础上,对新型除氟吸附剂的研发进行了展望。     

Prediction of monazite liberation from the silexitic rare earth ore of Catalão I

The theory for predicting the natural liberation of a mineral from texture measurements on unbroken fragments of ore is complex. Significant contributions in this area have been made by King, Random Fracture Model, Meloy, texture models, and Barbery, integral geometry. Although the theoretical aspects are well advanced, practical application of these methods is difficult, since they require precise measurement on images generated from large fragments of ore. Particularly, a suitable resolution for imaging must be selected that preserves the details of the texture and that completely encompass the larger features of a single phase in the section. In this work the liberation of monazite from a silexitic ore is predicted using sequences of images acquired from an ore fragment. The images in each sequence were stitched together. The mega-image strips are of high resolution and cover a large enough area that includes the largest features in the texture. Linear measurement is used with advantage, allowing the use of single strips rather than large area patches. The liberation of the monazite is predicted using King's random fracture model, followed by stereological transformation. The results are compared with liberation measurements carried out on comminuted particles of a rare earth ore of the same procedence.     

伊敏褐煤和腐殖酸中稀土元素的地球化学特征差异分析

运用电感耦合等离子体质谱(ICP-MS)及常规化学分析方法,对伊敏褐煤稀土元素含量等地球化学特征进行了分析,认为伊敏褐煤稀土元素主要赋存在黏土矿物和含钛矿物中,而黄铁矿、碳酸盐、硫酸盐等矿物中稀土元素含量低,具有稀释效应。稀土元素在脱灰煤提取腐殖酸和脱灰煤提取腐殖酸残煤中的赋存有一定的互补性,稀土元素在脱灰煤提取腐殖酸中相对富集程度为轻稀土<中稀土<重稀土,稀土元素在脱灰煤提取腐殖酸残煤中的相对富集程度为轻稀土>中稀土>重稀土,表明稀土元素在有机质中的分布具有重稀土主要赋存在腐殖酸中、轻稀土主要赋存在煤主体有机结构中的配分特征。     

煤中稀土元素研究现状及展望

稀土作为战略资源广泛应用于国防工业和高科技领域,我国作为稀土生产和出口大国,传统稀土储量日益减少。因此扩大我国稀土资源储量具有重要的经济价值和战略意义。稀土元素在特定的地质条件下可以在煤中富集,甚至达到工业品位。近年来,煤地质学家对煤中稀土元素开展了大量研究工作,取得了丰硕的研究成果。实测了新疆、鄂尔多斯、青海木里、宁夏鸳鸯湖等地125个样品中稀土元素含量,并结合前人资料对煤中稀土元素分布特征、赋存状态、富集影响因素、燃烧过程中迁移规律以及粉煤灰中稀土元素赋存状态和分离提取方法进行总结,为煤和粉煤灰中稀土元素的资源化利用提供理论依据。我国煤中稀土元素含量远高于美国煤中稀土元素含量,二连盆地-海拉尔盆地和西南川滇桂地区是我国两大煤中稀土元素成矿带。稀土元素在煤中主要以稀土矿物、有机化合物以及离子吸附的形式存在。煤中稀土元素的富集可能是不同时期沉积物源、搬运介质、沉积环境、风化淋滤和岩浆活动相互叠加的结果。煤燃烧过程中,稀土元素作为非挥发性元素在飞灰和底灰中进一步富集。粉煤灰中稀土元素赋存在玻璃体、含稀土矿物和非晶碳中。不同类型和来源的粉煤灰可能适用于不同的物理分选和化学提取方法。我国作为...     

从某低品位稀有、稀土复合矿浸出液中萃取铍的实验研究

初步探讨了用一种新型萃取剂NA处理某低品位稀有、稀土复合矿(BeO品位3%)的浸出液(Be质量浓度为4～6g/L),可获得品位达99.5%的工业氧化铍,并通过萃取、洗涤、反萃实验初步确定了各实验因素指标.     

TBP从硫酸体系中萃取铌的基础研究

探索了TBP在无氟硫酸体系中萃取铌的相关影响因素,并通过引入草酸改善TBP在低酸萃取效率低的问题.主要研究了硫酸浓度、硫酸盐浓度、混相时间及多级错流萃取对铌萃取率的影响.结果表明:铌萃取率随硫酸浓度升高而增加,并在酸度为8~9 mol/L时稳定在70%左右;硫酸盐对萃取有抑制作用;在混相时间为1 min时,萃取反应即可完成;在多级错流萃取试验中,高酸度条件下三级错流萃取可萃取大部分铌,但是低酸度条件下效果不理想,引入草酸可改善TBP对铌的萃取低的问题;用草酸溶液反萃有机相中的铌,两级反萃可反萃98%以上的铌.     

Effect of rare earth elements in copper metal and copper alloys

正Copper metal is a major non-ferrous material. It has better electrical and thermal conductivity(next to that of silver) and corrosion resistance than most of the metals. It is easy to be pressed into various electric and heat conductive products or semifinished parts, such as wires, rods, plates, belts and pipes in the devices.Rare earth elements have typical metallic properties and extremely active chemical properties. They can interact with almost all the elements except inert gas,     

A critical review on solvent extraction of rare earths from aqueous solutions

Rare earth elements have unique physicochemical properties that make them essential elements in many high-tech components. Bastnesite (La, Ce)FCO₃, monazite, (Ce, La, Y, Th)PO₄, and xenotime, YPO₄, are the main commercial sources of rare earths. Rare earth minerals are usually beneficiated by flotation or gravity or magnetic processes to produce concentrates that are subsequently leached with aqueous inorganic acids, such as HCl, H₂SO₄, or HNO₃. After filtration or counter current decantation (CCD), solvent extraction is usually used to separate individual rare earths or produce mixed rare earth solutions or compounds. Rare earth producers follow similar principles and schemes when selecting specific solvent extraction routes. The use of cation exchangers, solvation extractants, and anion exchangers, for separating rare earths has been extensively studied. The choice of extractants and aqueous solutions is influenced by both cost considerations and requirements of technical performance. Commercially, D2EHPA, HEHEHP, Versatic 10, TBP, and Aliquat 336 have been widely used in rare earth solvent extraction processes. Up to hundreds of stages of mixers and settlers may be assembled together to achieve the necessary separations. This paper reviews the chemistry of different solvent extractants and typical configurations for rare earth separations.     

溶剂萃取设备在我国铀水冶工艺中的应用

简要介绍了铀水冶工艺中溶剂萃取设备的类型、优缺点及其在国内的应用概况;对各种萃取设备进行了简要比较,进而对萃取设备的类型选择提出了建议。     

沁水盆地晚古生代煤中稀土元素地球化学特征

摘要：研究煤中稀土元素对分析成煤环境具有重要意义。运用电感耦合等离子质谱、X射线荧光光谱、X射线衍射等方法分析了沁水盆地晚古生代煤及其顶底板炭质泥岩、粉砂岩、灰岩和黄铁矿脉中稀土元素的地球化学特征,探讨了煤中稀土元素的赋存特征及富集成因。结果表明,沁水盆地晚古生代煤中稀土元素含量整体较低,剖面上太原组煤中稀土元素的含量大于山西组,平面上具有南高北低的分布特征。煤中稀土元素主要赋存在粘土矿物和黄铁矿中,碳酸盐矿物和氧化物中稀土元素含量较低,相当部分的稀土元素赋存在有机质中。相关分析表明,稀土元素与Si、Al关系密切。研究认为,沁水盆地煤中稀土元素的富集受控于聚煤古环境,煤层及其顶底板岩石中稀土元素的来源具有一致性,成煤时期海水对泥炭沼泽的影响导致太原组煤中相对富集重稀土,但没有导致Ce的亏损。     

酸法地浸采铀硫酸稀释放热应用研究

地浸采铀是我国砂岩型铀矿床开采的重要方法,硫酸因具有价格低廉、性质稳定及对矿石中铀浸出率高等优点成为酸法地浸采铀首选的浸出剂原料。然而,在酸法地浸采铀工艺中,配制浸出剂时存在大量热浪费的现象,将这些热量用于地浸采铀需加热的环节,不仅有助于提升工艺效果,还能有效降低成本。本文基于硫酸稀释放热理论计算和室内、现场试验,开展了不同工艺环节及参数对硫酸稀释热利用效率的影响研究,并确定了最佳工艺参数。结果表明,硫酸稀释热可改善地浸采铀工艺“淋萃流程”环节的反萃取效果,消除乳化现象,降低贫有机相及萃余水中的铀浓度,并能提高废液处理环节的蒸发池内废水温度和蒸发速度,从而减小蒸发池占地面积,降低成本。硫酸稀释放热原理简单,实现方法简便且高效低耗,将硫酸稀释热用于酸法地浸采铀可有效减轻工艺过程中存在的热浪费现象,具有明显优势。