Recovery of rare earth elements from phosphorites in the USSR

Data on the main rare earth compositions in the USSR are presented, showing that the most promising sources are phosphorites and apatites. The rate earth oxide content in the above ore concentrates reaches 1%. Technological schemes for recovering the total and individual rare earth oxides as byproducts have been developed. Extraction methods are used for recovering rare earths from nitrate solutions, with individual oxides more than 99.9% pure being obtained. Apatites are decomposed by nitric acid, yielding apart from fertilizers, strontium carbonate, sodium fluorosilicate, chalk and oxides of rare earth elements.     

Separation and recovery of rare earths via a dry chemical vapour transport based on halide gaseous complexes

The progress in the field of mutual separation of rare earths from the rare earth ores and their recovery from rare earth containing industrial waste by the dry chemical vapour transport (CVT) process mediated by the corresponding gaseous rare earth complexes with aluminum or alkali chlorides, RAI_nCl_3+3n or KRCl₄, is reviewed and discussed on the basis of their thermodynamic characteristics. The experimental results for the mutual separation and recovery of rare earth elements show the potential of this simple dry CVT process to substitute the conventional energy consuming complicated wet methods used at present for the costly preparation of the rare earths.     

离子吸附型稀土萃取分离新工艺

报道了萃取分离中国南部离子吸附型稀土矿的一种新工艺 ,第一步进行La Gd/(Gd)TbDy(HoY) /Ho LuY萃取分组 ,出口水相La Gd再进行Nd/Sm分组 ;中间出口的 (Gd)TbDy(HoY)组份进行Tb/Dy分离。在各系列的萃取段前设附加段来提高稀土浓度和回收率。该工艺流程衔接容易 ,昂贵的P50 7萃取剂使用量减少 ,处理能力增加 ,贵重Tb ,Dy在流程前部富集直收率提高 ,制取高纯Tb,Dy成本降低。适用于高钇矿经提钇后的低钇混合稀土矿、中钇富铕矿、低钇离子稀土矿的萃取分离     

Development of the Polish wasteless technology of apatite phosphogypsum utilization with recovery of rare earths

The most promising source of rare earth elements in Poland is apatite phosphogypsum, a waste product obtained in the process of phosphoric acid production from Kola apatite. Depending on the technology used, as the hydration ratio of calcium sulphate is changed from hemihydrate to dihydrate, the content of rare earths varies from 0.6% to 0.3% Ln₂O₃ respectively. Technological flow charts for recovering the rare earths as a byproduct have been developed. The basic process used in the technology consists of three steps: apatite phosphogypsum leaching with dilute sulphuric acid solution; separation of rare earth concentrates from leaching sulphuric acid by preconcentration via evaporization, liquid-liquid extraction or precipitation method; anhydrite production from purified phosphogypsum by recrystallization in concentrated sulphuric acid solution.     

Technology development for rare earth cleaner hydrometallurgy in China

China is the global leader in rare earth(RE)production using hydrometallurgical processes. Advantageous extraction techniques of rare earths from Baotou mixed rare earth minerals, bastnaesite, and ion-adsorption clays of rare earth deposits have been developed in China.The separation and purification technologies have also achieved rapid development. The industrial application processes for rare earth hydrometallurgy were summarized in the present paper. With the large demands and rapid development of rare earths, the issues of resources and environment are more prominent. This review gives an overview of the main processes that were developed in the past toward greener hydrometallurgy of rare earths in China. Based on the development of the rare earth industry,comprehensive utilization and cleaner production should still be focused on in the future, to support the sustainable development.     

稀土银合金显微组织观察与分析

对稀土银合金材料进行了金相观察和电子探针扫描分析以及显微硬度测定。实验结果表明,添加两种性质差交大的稀土元素可以充分发挥互补作用,改善银合金的组织与性能。含有稀土钇的银合金有较强的加工硬化效果和较好的抗高温氧化作用。稀土钇与轻稀土元素组合添加将有助于改善银合金的综合性能。     

Partitioning properties of rare earth ores in China

1 IntroductionChinese rare earth resources are dominant in theworld with a total amount up to 80% of the wholeworld resources. Rare earth resources in China notonly have high grade and various types, but also dis-tribute reasonably. There are many rare ea…     

Rare earth contribution in solid state electrolytes, especially in the chemical sensor field

In solid state electrolytes, rare earths are commonly used, and a number of their properties are exploited in these applications. Firstly, the rare earth can be utilized as a dopant to produce the mobile ion vacancies in an electrolyte and to enhance the ionic conducting characteristics. Secondly, they can be used as the principal constituent of the electrolytes. In both these case, the characteristics that the rare earths hold a stable trivalent state even though the main ionic mobility is via mono- or trivalent ions. Thirdly, the rare earth trivalent ion alone can migrate in some solids. This unexpected feature has been recently clarified by selecting the appropriate structure for the trivalent ion conduction in order to reduce the electrostatic interaction between the mobile ions and the framework of the solid. In solid electrolytes, only one ionic species can migrate. This feature is very advantageous for chemical sensor applications, especially from the viewpoint of selective and quantitative detection of specific gas species. The rare earth contribution to solid state electrolytes has been rapidly increasing, and has been expanding further the realms of application not only in the industrial field but also in the whole science field. Here, the rare earths contribution to the solid state electrolyte field is briefly reviewed.     

Commercial production of rare earth metals by fused salt electrolysis

The commercial production of rare earth metals by fused salt electrolytic methods is described. These methods are used to make mischmetal, cerium, lanthanum, and didymium (Nd + Pr). The feed materials consist essentially of anhydrous chlorides of the metal to be produced, augmented by additions of nonrare earth salts to yield an electrolyte with satisfactory properties for reduction. The rare earths are derived either from monazite or from bastnasite ores. The anhydrous chlorides are manufactured from the hydrated chlorides by methods which minimize oxidation or hydrolysis. Alternatively, anhydrous chlorides may be used which result from the direct chlorination of rare earth ores by the Gold-schmidt process. These are particularly suitable for electrolysis due to their very low oxychloride content. Fluorides and oxides of the rare earths are produced by wet chemical methods to provide the relatively small quantities of these compounds now used for commercial fused salt electrolysis. Reduction cells in use today are constructed mainly from a) ceramics, b) graphite, or c) iron. The advantages and disadvantages of these types of cells are described together with the typical products which result from their use. Primary attention is given to production of mischmetal (mixed rare earth metal), which is the rare earth metal produced on the largest scale today. Brief reference is made also to production of cerium, lanthanum, and didymium (Nd + Pr) metal. Finally, a resume of the current uses of these metals is presented with reference to recent trends in the industrial applications of the rare earth metals.     

AN IMPROVEMENT ON SINTER QUALITY OF BAOTOU IRON ORE CONCENTRATE

本文对包头精矿烧结矿的宏观结构、微观结构及矿物组成进行了岩相及矿相研究,并对其中的稀土矿物等进行了电子探针分析,对烧结矿中主要胶结相矿物——枪晶石进行人工合成,测定了枪晶石的抗压强度及耐磨性. 试验研究了硅(SiO_2),氟(CaF_2)对包头精矿烧结矿强度的作用机理,测定了随着烧结矿中Si、F_2含量的变化与其液相性质——粘度及表面张力的关系,以及对烧结矿结构及强度的影响. 试验证明,精矿中的F_2是影响烧结矿强度的主要因素,其次是Si低胶结相量少,枪晶石的抗压强度低耐磨性差也是影响烧结矿强度的一种因素. 根据实验结果提出了改进包头精矿烧结矿质量的措施,并在生产中获得成功的应用.     

Internal friction of the glassy tektites

Tektites are naturally occurring glasses, perhaps of meteoritic origin. They occur all over the world. They range in size from μm to decimeter. They are based on the compounds silica and alumina, with smaller concentrations of alkali metal and transition metal oxides. Their origin is in vigorous dispute; some scientists think they are of terrestrial earth origin, others believe they come from interplanetary space, as is true of meteorites. We have secured seven specimens from various regions of the earth and have measured the internal friction spectrum of several in the kilocycle frequency range above room temperature, where internal friction peaks of synthetic glasses have been observed. A well defined loss peak is observed around 500 K in a number of specimens. We have also measured the loss spectrum of obsidian and of blast furnace slag. From comparison of these measurements, we conclude that tektites are probably of volcanic origin, the loss peaks being associated with the reorientation of Fe–oxygen complexes.     

稀土对化学热处理催渗作用的机理探讨

通过对稀土在渗剂中和钢中作用的不同研究结果,探讨了稀土对化学热处理催渗作用的机理,并认为稀土影响渗层的原因之一在于形成了稀土周围含碳、氮的原子气团。     

Recovery of waste rare earth fluorescent powders by two steps acid leaching

The effects of the acid leaching and alkali fusion on the leaching efficiency of Y,Eu,Ce,and Tb from the waste rare earth fluorescent powders were investigated in this paper.The results show that hydrochloric acid is better than sulfuric acid in the first acid leaching,and NaOH is better than Na2CO3in the alkali fusion.In the first acid leaching,the Wloss is 20.94%when the waste rare earth fluorescent powders are acid leached in H?concentration 3 mol L-1and S/L ratio 1:3 for 4 h due to red powders dissolved.The better results of the alkali fusion can be got at 800℃ for 2 h when the NaOH is used.The blue powders and the green powders can be dissolved into NaAlO2and oxides such as rare earth oxide(REO).The REO can be dissolved in H?concentration 5 mol L-1,S/L1:10 for 3 h in the second acid leaching.The leaching rates of the Y,Eu,Ce,and Tb are 99.06%,97.38%,98.22%,and 98.15%,respectively.The leaching rate of the total rare earth is 98.60%.     

白云鄂博混合型稀土精矿在惰性气氛下的热分解行为（英文）

为了开发和应用白云鄂博混合型稀土精矿的先进冶炼技术，采用Kissinger公式、TGA-DSC和XRD等分析方法，研究在氮气氛下白云鄂博混合型稀土精矿的热分解行为，包括热分解动力学、物相变化规律、铈氧化效率以及物相变化对稀土浸出率的影响。结果表明：在500～550℃焙烧时，焙烧质量损失率约10%、热分解活化能(E_a)为148 k J/mol。550℃焙烧2 h，白云鄂博混合型稀土精矿中氟碳铈矿完全分解，并转化为稀土氧化物和氟氧化物，铈氧化率最大值为0.58%。600℃焙烧2 h，稀土最大浸出率达49.1%。     

混合稀土氧化物对镁质耐火材料结构与性能的影响

研究了添加Y2O2的混合稀土氧化物对镁质耐火材料的烧结性、力学性能和显微结构的影响。结果表明：添加含Y2O3的混合稀土氧化物可以促进镁质耐火材料的烧结，提高材料的力学性能，同时改善材料的组织结构。含Y2O3的混合稀土氧化物的添加，使镁质耐火材料的结合方式由硅酸盐相结合转化为高熔点的稀土硅酸盐相结合，从而导致镁质耐火材料的高温强度得到显著地提高。     

用磷酸三丁酯浸渍树脂从硝酸介质中提取铈(Ⅳ)(英文)

用磷酸三丁酯(TBP)溶剂浸渍高分子交换树脂XAD-16来制备浸渍树脂。在室温下,将未稀释的磷酸三丁酯与树脂按液固比6(磷酸三丁酯体积与树脂质量比)浸渍24h得到的浸渍树脂的质量比为1.944;按液固比3.0浸渍24h,得到的浸渍树脂的质量比为1.88。将从埃及独居石矿砂得到的含37%铈、1.6%钍和40%三价稀土氧化物的氧化铈(IV)精矿浸出得到的硝酸铈溶液,用所制备的浸渍树脂从该铈溶液提取铈。在室温下,用该浸渍树脂从硝酸介质中提取Ce(IV)的效果是令人满意的。在溶液中含51.57g/L铈、2.48g/L钍、5.0mol/L游离硝酸,溶液与树脂比为10.0,浸渍时间为5.0min的条件下,该浸渍树脂对Ce(IV)的负载容量达到理论值(173g/kg(Ce/SIR))的95.6%。在其他条件不变的情况下,将铈的浓度提高到91.43g/L,浸渍树脂对Ce(Ⅳ)的负载容量达到理论值的98.75%。     

稀土氧化物对贮氢合金电极电化学性能的影响

研究了稀土氧化物La_2O3_,CeO_2,Nd_2O_3和Y_2O_3对AB_5型贮氢电极电化学性能的影响。研究表明,除Y2_O3_外,其余的稀土氧化物可提高贮氢电极的1C放电容量和放电电压,延长贮氢电极的循环寿命,且对贮氢电极性能有利的顺序为:La2_O3_>CeO2_>Nd2_O3_;稀土氧化物添加量越多,贮氢电极的循环稳定性越好,但对贮氢电极的1C放电容量和放电电压的影响存在最佳值。造成这些结果的原因是:稀土氧化物增大贮氢合金颗粒间的接触电阻;稀土氧化物的催化作用;稀土氧化物对镍催化剂的稳定作用及抑制贮氢合金进一步氧化的作用。     

复合稀土氧化物对Ti-Al/WC涂层组织和摩擦学性能的影响

采用等离子喷涂方法制备了未添加稀土氧化物以及含有不同复合稀土氧化物的Ti-Al/WC涂层,使用自带能谱仪的扫描电镜、X射线粉末衍射仪和电子天平对各类涂层的磨损表面及截面组织形貌、残余应力和磨损量进行了观察和检测,使用摩擦磨损试验机比较和分析了不同类型涂层的耐磨性能。结果表明:含有稀土氧化物的Ti-Al/WC涂层内部晶粒得到细化,颗粒物含量大幅度减少,孔洞变小,裂纹数量及尺寸显著降低。与只含一种稀土氧化物的涂层相比,复合稀土氧化物对涂层微观组织改善情况更加明显。当同时加入CeO₂、Y₂O₃和La₂O₃后,涂层组织中的显微缺陷最少,各成分分布最为均匀,截面显微形貌最好,此时,涂层的残余应力达到最小值275.7 MPa,且耐磨性最强,总磨损量仅有16.8 mg。与未添加稀土氧化物的涂层相比,二者分别减少了30.3%和69.8%。     

TUNGSTEN ELECTRODES CONTAINING THREE TYPES OF RARE EARTH OXIDES

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The fascination of the rare earths—then, now and in the future

The rare earths have long been a subject of fascination to chemists and physicists. Herein, I comment on some of the prehistory leading up to the advent of the Judd–Ofelt theory of the intensities of their remarkable spectra, the origins of the Judd–Ofelt theory and its early applications. I then consider subsequent developments and extensions of the theory, its current status and its relevance to current problems of interest in rare earth spectroscopy and the future of rare earth studies.