Origin of uranium and rare earth minerals in bone detritus from rare metal deposits

In order to ascertain the forms in which uranium is present in ores of the Melovoe rare metal sedimentary deposit of uranium and rare earth minerals (South Mangyshlak), we investigated a series of typical ore samples that were collected earlier; both the uranium content and the total content of rare earth metals in them lay within 0.1–0.3%. The study was carried out by analytical electron microscopy using transmission electron microscopy and scanning electron microscopy, electron microdiffraction, and microprobing. It was ascertained that both uranium and rare earth elements are present in ore mostly associated with biogenic phosphate in the form of natural minerals, such as uraninite, ningyoite, coffinite, autenite, and churchite. Iron hydroxides and graphitized organic matter are present in some samples. It is assumed that the co-occurrence of uranium and rare earth elements, which is nontypical for the sedimentary process, resulted from secondary epigenetic processes and alternation of reducing and oxidizing environmental conditions.     

云南安宁磷矿中稀土元素分布规律和赋存状态研究

磷矿伴生稀土元素是获取稀土资源的重要途径。我国磷块岩型稀土矿分布广,稀土含量高,具有综合回收价值,是仅次于独立稀土矿床的伴生稀土资源。本文主要研究云南安宁磷矿中稀土元素分布规律和赋存状态,并比较了磷矿石中稀土元素总量与磷含量的关系,结果表明磷矿石中稀土氧化物总量为72×10^-6～1 050×10^-6,与磷含量呈一定的正相关关系。另外通过光学显微镜及电子显微镜观察发现,安宁磷矿中缺乏独立的稀土矿物,只在部分海绿石中找到了独立的稀土矿物(可能为独居石和褐帘石)。LA-ICP-MS分析结果表明,胶磷矿单矿物稀土元素含量在770×10^-6～920×10^-6之间,而白云石单矿物稀土元素含量均低于34×10^-6,石英单矿物的稀土元素平均含量为180×10^-6。由于部分独立的稀土矿物的存在,海绿石矿物中稀土元素总量可高达2 947.27×10^-6～3 159.87×10^-6。综合分析结果表明,安宁磷矿中稀土元素主要以类质同像的...     

Specific features of the structure and evolution of u and REE-bearing organic phosphate deposits in the southern mangyshlak region

Specific structural features of giant fishbone detritus accumulations, which represent organic phosphate deposits with uranium and rare earth elements, are scrutinized. Based on the detailed examination of phosphate orebodies, regularities of the distribution and localization of uraniferous fish remains are studied. The obtained results have made it possible to reconstruct paleotectonic and paleogeographic conditions of the formation of orebodies, as well as the mechanism for the accumulation of metalliferous bone detritus.     

Geochemistry of phosphate bearing sedimentary rocks in parts of Sonrai block,Lalitpur District,Uttar Pradesh,India

Major, trace and rare earth elements of phosphatic rocks around Sonrai block of Paleo-Mesoproterozoic age having phosphatic breccia, quartzite, shale, sandstone, limestone and ironstone, have been determined to evaluate their correlation, relationship with the phosphorus content, the nature of possible substitution of various elements and regional distribution pattern over the area. The study indicates that the number of elements is substituted in the apatite structures; few of them are associated with phosphate and carbonate minerals. The variable concentration of major, trace and rare earth elements in the phosphatic rocks has been influenced by various physico-chemical processes involved during weathering and leaching of the source rocks. The distribution of the major, trace and rare earth elements is controlled by the environmental variations in the sediment water interface. The majority of trace elements were mainly influenced by the principle adsorbents like the phosphate minerals in addition to clay, iron oxides and silicate minerals. The PAAS normalized REE patterns of Sonrai block of phosphorites are characterized by negative Ce anomalies and Positive Eu anomalies. It is inferred from the distribution and interrelationship of major, trace and rare earth elements that the deposition of phosphate minerals might have occurred in highly oxidizing to slightly reducing conditions in supratidal to intertidal continental margins and shallow marine environment. The deposition was controlled by marine upwelling leading to excess charge of phosphate in certain zones of phosphogenic basins, lithologic facies variations in restricted circulations of basinal waters and electrochemical factors such as negative Eh, pH and other factors, which influenced the deposition of phosphates. The replacement, precipitation in voids and fissures and diagenesis were also important mechanisms of phosphate generation in Sonrai basin. The main source for various elements may be the minerals of cratonic mass of Bundelkhand Granitic Complex, a basement of Bijawar Basin, which also provided land derived phosphorus through weathering of the terrestrial cover.     

应用能谱-扫描电镜和X射线衍射技术研究原煤伴生矿物中稀土和放射性元素赋存形式

研究原煤中稀土及放射性元素的赋存形式,对原煤是集中还是分散利用、燃煤过程中粉煤灰的排放截留、从原煤或粉煤灰中提取稀土及放射性元素等方面都具有指导意义。由前人研究可知不同矿区原煤中稀土及放射性元素的赋存形式有差异。本文研究了山西省霍西煤田两个矿区175个煤样中稀土及放射性元素的赋存形式,应用背散射电子图像(BSEI)定位分析区域,应用BSEI、能谱-扫描电镜法(EDX-SEM)中的面分析(EDS-mapping)和粉晶X射线衍射法确定了主要伴生矿物,应用BSEI和EDX-SEM中的点分析(EDS-point)确定了微量伴生矿物。在煤样中发现了铈镧钕钇镝钪六种稀土元素及一种放射性元素钍,其中铈、镧和钕主要以磷酸盐形式伴生于高岭石类矿物中,部分伴生在含氧化铝或氧化硅较多的矿物中,少量存在于碳中;钇、镝以磷酸盐或氧化物形式独立存在于碳中;在部分锆石、独居石中分别发现了钪和钍。研究表明,该矿区煤样中稀土元素主要以细粒自生矿物的形式伴生在其他矿物中,少数以独立矿物的形式存在于碳中,放射性元素钍伴生在独居石中。     

桂北沙子江铀矿床沥青铀矿原位微区年代学和元素分析:对铀成矿作用的启示

微区原位分析是地球科学研究的重要手段,但这些分析技术在华南热液铀矿床中的应用相对较少,限制了对铀矿床成矿机理的深入认识。沙子江铀矿床是华南著名的花岗岩型热液铀矿床。本文利用电子探针(EMPA)、激光电感耦合等离子体质谱(LA-ICPMS)以及二次离子探针(SIMS)等微区原位分析技术,对沙子江铀矿床中的沥青铀矿开展了U-Pb同位素年代学及元素组成研究,确定了沥青铀矿的形成时代及成分特征,并探讨了蚀变作用对沥青铀矿成分及其表面年龄或化学年龄的影响。电子探针分析结果显示,该沥青铀矿以富铀和钙、极低含量的ThO_2和稀土元素为特征,揭示其为低温热液成因,成矿热液富含Ca。LA-ICP-MS分析结果显示,沥青铀矿的稀土元素总量较低,其配分模式呈轻稀土富集型,具有明显的负Eu异常,与赋矿围岩豆乍山花岗岩的稀土元素组成相似,暗示其铀源可能与豆乍山岩体有密切的关系。蚀变和未蚀变沥青铀矿成分的对比研究显示,蚀变作用会导致硅元素大量进入沥青铀矿晶格,造成铀和铅的丢失,从而影响沥青铀矿的表观年龄或化学年龄,但沥青铀矿的稀土元素配分模式不会受到蚀变的影响。未蚀变沥青铀矿的SIMS微区原位分析获得的U-Pb年龄为101. 3±4. 5Ma,表明沙子江铀矿床存在100Ma左右的铀成矿事件。受岩石圈伸展控制形成的富CO流体与富铀花岗岩相互作用浸取出花岗岩中的铀,并在合适的构造部位沉淀形成了沙子江铀矿床。     

桂东北铀矿区各类型铀矿床中沥青铀矿的稀土元素分布模式的研究

该文研究了桂东北地区三种不同类型铀矿床中沥青铀矿及其围岩的稀土元素分布模式。三种类型铀矿床的沥青铀矿的稀土元素分布模式十分相似,这反映出它们形成的物理化学条件可能近似。沥青铀矿与含矿围岩的稀土元素分布模式类同,说明成矿物质主要由围岩本身提供;有可能根据沥青铀矿的稀土元素分布模式来追溯铀源。     

A new method for processing of low-grade monazite concentrates

It is very tedious to separate thorium and rare earth elements from their accompanying constituents in low-grade monazite (concentrate 50%) containing large amount of phosphorus species, illiminite, silica and zircon. Therefore, trials have been suggested to develop a new procedure to enhance the separation process of the light lanthanides from low-grade Egyptian monazite concentrates. The first point is focused on the removal of phosphorus species from the digested low-grade monazite with sulfuric acid in order to get more convenient separation. The removal was accomplished by extractive washing of sulfate paste with different alcohols. The results showed that the extractive removal of phosphorus species was not effective due to the complex nature of low-grade monazite concentrate. The second point is focused on the enhancement of separation process of uranium, thorium and rare earth elements by new ratio of sulfuric acid and develops the classical separation process. By this modified procedure, the overall results obtained revealed that the unleached residue contains mainly Si, Fe, Zr, and Ti while the elements of main consideration such as uranium, thorium and light rare earth elements were completely leached. Thorium and light rare earth elements (LREEs) were directly separated as white precipitate while the uranium was moved to the green acid solution with most of phosphorus species. This throws light on the possibility of separation of thorium and light rare earth elements from uranium, which represents a novel method.     

基于PCA-SVM算法对稀土元素与稀土判别指标耦合数据集的铀矿床分类

不同类型铀矿床的沥青铀矿/晶质铀矿具有不同的稀土元素组成,其组成可作为判别铀矿床类型的重要指标。采用基于Python语言的主成分分析（principal component analysis,PCA）与支持向量机（support vector machines,SVM）结合的分类模型,对收集到的全球已知6种类型铀矿床的216组沥青铀矿/晶质铀矿稀土元素数据进行研究。以216组数据为训练集,通过数据清洗、特征缩放、PCA特征提取、网格搜索和交叉验证参数寻优构建SVM分类模型,对24组同变质型胡家峪晶质铀矿进行智能识别。研究结果显示：仅使用稀土元素的14维训练集最优模型判定胡家峪晶质铀矿类型的测试准确率为0.4%;由稀土元素、稀土总量、轻重稀土比、铕异常组成的17维训练集最优模型的测试准确率为75.0%,较14维训练集提高74.6%,模型泛化能力强;而通过传统稀土元素配分曲线、w（ΣREE）-（LREE/HREE）_N图解不能有效判定胡家峪晶质铀矿类型。本次研究表明,PCA-SVM算法对增有传统稀土判别指标数据集进行挖掘可有效厘定铀氧化物成因类型,效果明显优于单纯的稀土元素数据集以及传统的稀土配分曲线、w（ΣREE）-（LREE/HREE）_N图解。     

中条山地区早前寒武纪岩石 含铀矿化岩石稀土元素与铀的关系及其意义

本文研究了中条山地区基底涑水杂岩,含矿层中条群岩石和铀矿化岩石的稀土元素特征及其与铀元素的关系。发现稀土元素,尤其是重稀土元素对铀的区域富集及铀矿化作用有一定的指示意义。     

“关键资源地球化学勘查”专辑特邀主编寄语——关键元素分布与关键资源勘查

关键资源已经成为工业4.0和低碳能源不可替代的原材料。构成关键资源的元素有50余种, 这些元素是现代社会的先进制造、电子产品、低碳能源、国防安全、生物医药等必须的原材料, 因此也称为关键元素。地球化学勘查是研究和探测关键元素分布和超常富集, 寻找关键资源行之有效的方法。中国在关键元素的分布和深部探测地球化学领域走在了国际前列, 形成了从全球尺度、全国尺度、矿区尺度直到纳米尺度地球化学探测技术体系, 实现从二维到三维、从浅表矿到千米深度矿产探测能力的飞跃, 不仅圈定了一批全国稀土、锂、铀的超常富集区, 而且取得了多处深部金矿和铜矿勘查的重大突破。本专辑选择部分研究成果介绍了稀土元素、新能源金属(铀、锂、钴)、金、铜等关键资源地球化学勘查中取得的新进展和成果。为了响应国家号召“把论文写在祖国大地上”, 专辑作者把优质素材形成的论文发表在自己的杂志上, 作为本期特邀主编对他们的奉献精神表示衷心感谢和崇高的敬意！     

X射线荧光光谱法测定稀土精矿中的稀土元素分量

氟碳铈矿、独居石、磷钇矿和风化壳淋积型稀土矿四种稀土精矿样品采用化学法预分离富集,X射线荧光光谱法测定样品中稀土元素和伴生的铀、钍元素含量,选择以硼酸盐为主的混合熔剂高温熔融制样,消除矿物间存在的矿物结构影响,通过加大熔剂稀释比降低元素间的基体效应,人工标准样品绘制标准曲线,用数学校正方法校正元素间的谱线重叠效应。对淋积型稀土矿样品重复测定12次,方法检出限为0.9～42.1μg/g,待测组分的相对标准偏差(RSD)均小于10%,测定结果与电感耦合等离子体质谱法的测定值基本吻合。此方法应用于国家一级标准物质稀土标准样品定值工作,检出限和精密度能够满足分析要求,报出数据被采用率达到100%。     

浙江临安石室寺NYF型伟晶岩中稀有稀土金属的矿物学行为与成矿过程

浙江临安石室寺伟晶岩位于河桥岩体西北面，属于典型的Nb-Y-F （NYF） 型伟晶岩，富含大量稀有稀土矿物。本文在野外考察和显微镜观察的基础上，结合电子探针背散射电子图像观察与矿物化学成分分析，系统鉴定了石室寺NYF 型伟晶岩中的稀有稀土矿物，揭示了稀有稀土元素的富集、迁移、结晶与成矿过程。研究结果表明：（1） 石室寺伟晶岩中的稀有稀土矿物有铌钽矿物（铌铁矿、铌锰矿、重钽铁矿、细晶石等）、钇矿物（褐钇铌矿、黑稀金矿）、钨矿物（黑钨矿、 白钨矿、铌钨矿物）、铈矿物（独居石、氟铈矿、氟碳铈矿） 和钍矿物等。（2） 铌钨系列矿物的WO3含量在8.30~70.51 wt%之间呈规律变化，可能为铌铁矿与黑钨矿之间形成的一系列多体矿物。（3） 铌铁矿LA-ICP-MS U-Pb 定年结果显示，石室寺伟晶岩的形成年龄为133±2 Ma，与河桥花岗岩具有成因联系。（4） 石室寺NYF 型伟晶岩中稀有稀土元素的成矿过程与其岩浆的结晶演化密切相关：岩浆阶段，锆石、钍石与独居石等矿物最早晶出；岩浆—热液阶段，黑稀金矿、铌铁矿、褐钇铌矿、氟铈矿等稀有稀土矿物逐渐结晶；热液阶段，黑钨矿、铌钨矿物相继形成，同时早期的独居石、氟铈矿受晚期热液交代形成次生铈矿物。     

浙江临安石室寺NYF型伟晶岩中稀有稀土金属的矿物学行为与成矿过程

浙江临安石室寺伟晶岩位于河桥岩体西北面,属于典型的Nb-Y-F （NYF） 型伟晶岩,富含大量稀有稀土矿物。本文在野外考察和显微镜观察的基础上,结合电子探针背散射电子图像观察与矿物化学成分分析,系统鉴定了石室寺NYF 型伟晶岩中的稀有稀土矿物,揭示了稀有稀土元素的富集、迁移、结晶与成矿过程。研究结果表明：（1） 石室寺伟晶岩中的稀有稀土矿物有铌钽矿物（铌铁矿、铌锰矿、重钽铁矿、细晶石等）、钇矿物（褐钇铌矿、黑稀金矿）、钨矿物（黑钨矿、 白钨矿、铌钨矿物）、铈矿物（独居石、氟铈矿、氟碳铈矿） 和钍矿物等。（2） 铌钨系列矿物的WO3含量在8.30~70.51 wt%之间呈规律变化,可能为铌铁矿与黑钨矿之间形成的一系列多体矿物。（3） 铌铁矿LA-ICP-MS U-Pb 定年结果显示,石室寺伟晶岩的形成年龄为133±2 Ma,与河桥花岗岩具有成因联系。（4） 石室寺NYF 型伟晶岩中稀有稀土元素的成矿过程与其岩浆的结晶演化密切相关：岩浆阶段,锆石、钍石与独居石等矿物最早晶出;岩浆—热液阶段,黑稀金矿、铌铁矿、褐钇铌矿、氟铈矿等稀有稀土矿物逐渐结晶;热液阶段,黑钨矿、铌钨矿物相继形成,同时早期的独居石、氟铈矿受晚期热液交代形成次生铈矿物。     

沙特阿拉伯Jabal Twalah地区铀/钍矿化特征与成矿机制

目前,沙特阿拉伯西北部Jabal Twalah地区铀钍资源勘查程度较低,对该地区的铀成矿机制研究相对薄弱.本文主要对该地区新发现的伟晶岩型和花岗岩热液型铀矿化带的矿化特征和成矿机制开展研究.区内与铀钍矿化相关的伟晶岩和围岩花岗岩中锆石LA-ICP-MS U-Pb年龄分别为638.6±3.2 Ma和632.5±1.5 Ma,两者时代基本一致.综合岩相学、地球化学以及扫描电镜能谱分析等研究结果,发现矿化伟晶岩强烈富集U、Th、稀土及稀有金属元素,复杂的高温蚀变矿物组合特征暗示可能经历了岩浆期后热液的改造,改造前后矿化伟晶岩中的铀和钍未发生分离,以副矿物形式存在而无独立铀矿物,具岩浆矿物组合的特征,如金红石、锆石、氟碳铈矿、磷钇矿、钍石等.花岗岩热液型单铀矿化带的地表样品中铀矿物主要为硅铅铀矿和硅钙铀矿,脉石矿物主要为赤铁矿、萤石、石英以及少量方解石,铀矿化受控于高铀含量的碱性花岗岩、强烈硅化构造破碎带以及晚期酸性基性脉岩活动等因素.强烈硅化的构造破碎带及其转折部位或者与脉岩交汇部位是今后重要的找矿方向.     

Ion Exchange Chromatography Applied to the Separation and Accurate Determination Of Some Trace Elements in Rocks

Ion exchange chromatography is extremely well suited for the complete or partial separation of trace and ultra-trace elements from rooks and minerals. Selective methods are described for the separation of traces of lithium, beryllium, vanadium, uranium, strontium, barium, sodium, potassium and rare earth elements, and their determination in rook samples. The methods are especially useful for accurate standardization work. Some typical elution curves and results for the concentration of these trace elements in the six South African NIM-rock standards and some international standard rocks are presented.     

贵州织金下寒武统黑色页岩矿物岩石成分及资源利用特征

通过野外采样、化学分析、电子探针(EPMA)和X射线衍射(XRD)分析等手段,研究了贵州织金地区黑色页岩矿物成分、化学组分、微量元素、稀土元素特征。研究区矿样化学成分以SiO_2和Al_2O_3为主,且具有高K低Na的特征。电子探针和X射线衍射分析表明,研究区黑色页岩主要矿物组成有石英、粘土矿物、白云石及黄铁矿等。织金黑色页岩中Pb、Ni、U、V、Cr等金属元素存在不同程度的富集,稀土元素总量为153.2×10~(-6)~224.89×10~(-6),属轻稀土元素富集型。同时从多金属层、页岩气、页岩提钾及近底部含磷铀矿资源等方面讨论了织金黑色页岩资源化利用。织金黑色页岩多金属层含有Mo、V、Ni、Ag及U等多金属元素,具综合利用价值;其中有机碳含量达到页岩气开发大于2%的条件,可进一步开展研究;页岩中伊利石含量较多,可提取黑色页岩中的钾制备含钾复合肥;黑色页岩底部与磷矿层接触带产出磷铀矿,主要为胶状磷铀矿,接触带可作为铀矿找矿的标志层。     

U redox fronts and kaolinisation in basement-hosted unconformity-related U ores of the Athabasca Basin (Canada): late U remobilisation by meteoric fluids

Proterozoic basement-hosted unconformity-related uranium deposits of the Athabasca Basin (Saskatchewan, Canada) were affected by significant uranium redistribution along oxidation–reduction redox fronts related to cold and late meteoric fluid infiltration. These redox fronts exhibit the same mineralogical and geochemical features as the well-studied uranium roll-front deposits in siliclastic rocks. The primary hydrothermal uranium mineralisation (1.6–1.3 Ga) of basement-hosted deposits is strongly reworked to new disseminated ores comprising three distinctly coloured zones: a white-green zone corresponding to the previous clay-rich alteration halo contemporaneous with hydrothermal ores, a uranium front corresponding to the uranium deposition zone of the redox front (brownish zone, rich in goethite) and a hematite-rich red zone marking the front progression. The three zones directly reflect the mineralogical zonation related to uranium oxides (pitchblende), sulphides, iron minerals (hematite and goethite) and alumino-phosphate-sulphate (APS) minerals. The zoning can be explained by processes of dissolution–precipitation along a redox interface and was produced by the infiltration of cold (<50°C) meteoric fluids to the hydrothermally altered areas. U, Fe, Ca, Pb, S, REE, V, Y, W, Mo and Se were the main mobile elements in this process, and their distribution within the three zones was, for most of them, directly dependent on their redox potential. The elements concentrated in the redox fronts were sourced by the alteration of previously crystallised hydrothermal minerals, such as uranium oxides and light rare earth element (LREE)-rich APS. The uranium oxides from the redox front are characterised by LREE-enriched patterns, which differ from those of unconformity-related ores and clearly demonstrate their distinct conditions of formation. Uranium redox front formation is thought to be linked to fluid circulation episodes initiated during the 400–300 Ma period during uplift and erosion of the Athabasca Basin when it was near the Equator and to have been still active during the last million years. A major kaolinisation event was caused by changes in the fluid circulation regime, reworking the primary uranium redox fronts and causing the redistribution of elements originally concentrated in the uranium-enriched meteoric-related redox fronts.     

赣南花岗岩风化壳型稀土矿床中纳米级稀土矿物的研究

为揭示次生风化成因稀土矿物的赋存形态和分布特征,对赣南安远岗下稀土矿区花岗岩风化壳剖面进行了研究。采集风化壳不同层位的样品进行分选、提纯,场发射扫描电镜和透射电镜研究结果表明,与稀土矿物紧密相关的粘土矿物是高岭石和埃洛石等,风化壳中发现的纳米级稀土矿物既有附着于其他矿物表面的微细颗粒,也有呈集合体存在的稀土矿物(可能为方铈石),这一现象有助于进一步认识风化壳稀土矿床的形成过程。