赣南清溪离子吸附型稀土矿元素迁移富集特征研究

离子吸附型稀土矿床是中国特有的稀土资源。对这一类型矿床及周边的地质环境,风化壳中稀土进行研究具有较高的产学研价值。本文通过对中国赣南典型稀土矿区花岗岩风化壳进行元素地球化学分析,并结合相关地球化学参数与图解,结果表明：研究区成矿花岗岩风化壳形成于强化学风化条件,发育成熟度高,处于晚期去Si阶段;稀土元素地球化学参数显示,风化壳整体的稀土配分特征主要继承于成矿母岩;稀土元素主要以离子交换态在风化剖面中迁移,并受pH值、微生物活动、氧化还原条件等多种因素控制。     

黄山景观流域溶解态稀土元素地球化学特征

对黄山景观流域径流中溶解态稀土元素进行了研究,以探讨其地球化学特征与物质来源。结果表明,其主要来源为岩石化学风化,其次为大气输入。稀土元素含量枯水期高于丰水期,与蒸发富集效应有关。流域源头稀土元素含量高、重稀土相对富集,中下游稀土含量低、轻稀土相对富集,反映了源头花岗岩到中下游沉积岩对其相应控制。流域水体中Ce为负异常,表现出对流经原岩如花岗岩的继承;Eu为正异常,归因于花岗岩中斜长石/钾长石等矿物的优先风化释放。Y/Ho比值在空间上存在分异,主要为流经岩性不同所致,季节性分异则受到了水/粒相互作用的影响。研究表明,黄山景观流域溶解态稀土元素来源与迁移受流经岩性尤其花岗岩的影响显著。     

赣南离子吸附型稀土矿床成矿特征概述

赣南是我国离子型稀土资源的主产区之一,其成矿母岩分布广,成矿条件优越,稀土配分类型多样。本文从成矿背景和矿床分布规律,成矿母岩和矿体赋存特征,以及矿石中稀土的赋存状态和配分类型等方面较为详细地总结了赣南稀土矿床成矿地质特征。     

赣南陂头一带风化壳淋积型稀土矿成矿地质特征

对陂头一带风化壳淋积型稀土矿点进行野外调查和室内综合研究表明:变质基底层、岩浆多期活动和岩浆期后脆性断裂构造活动是风化壳淋积型稀土矿的形成主因。变质基底构造层中泥质板岩、炭质板岩和变凝灰质砂岩中RE2O3含量高,在岩浆侵位过程中带入了大量的稀土元素,在含矿母岩顶部可见大量的未熔完全的基性捕掳体。受后期热液交代蚀变,导致含矿母岩中长石矿物粘土化强烈,对水具有胀缩性,易碎岩成矿。岩浆期后"X"型脆性共轭剪切断裂为雨水渗漏贯通提供了良好的通道。含矿母岩在各个地质历史阶段受古气候多次变化的影响加速了含矿母岩的风化程度。表土层的保湿渗水呈酸特性促进了稀土矿的形成。区内变质基底炭泥质板岩和变凝灰质砂岩、岩浆期后脆性断裂、含基性捕掳体的红褐色黑云母二长花岗岩是风化壳淋积型稀土矿的地质宏观找矿标志。     

离子型稀土矿石颗粒粒度分布型式及其成因研究——以江西赣县大埠稀土矿床为例

颗粒粒度分布是离子吸附型稀土矿石(风化花岗岩)的基本物理性质之一,对矿石的渗透性能、水-岩相互作用及物理力学性质等都有重要影响,从而影响离子型稀土矿体的开采及其边坡稳定性。以大埠稀土矿床为例,探讨离子型稀土矿石的颗粒粒度分布型式及其成因。水洗筛分结果表明,大埠稀土矿石总体细砾-粗砂和粉-黏粒含量高,其中间组分含量低,呈现出"双峰"式分布特征。通过Q型聚类分析将大埠稀土矿石划分为4种颗粒粒度分布型式,即"左倾双峰"式(A型)、"右倾双峰"式(B型)、"水平双峰"式(C型)和"左抬双峰"式(D型)。成因分析表明,A型和B型分布型式主要是风化程度不同的结果,属于基本的粒度分布型式。水土流失可导致A型向B型转化;细颗粒垂向迁移后再沉积,使局部细颗粒含量升高,则分布型式由B型转化为C型。溶解的Si O2向下迁移,在较深处发生沉淀和重结晶作用,使砾的粒度和含量明显升高,则形成D型分布型式。     

广西龙塘蚀变流纹岩风化作用初期稀土元素地球化学研究

广西龙塘蚀变流纹岩在风化作用初期显示稀土元素一定的富集,但与风化母岩相比,稀土元素并未显示出分异特征.研究发现初期风化样品的针铁矿有微米大小的稀土磷酸盐矿物水磷铈石产出.电子探针能谱分析表明,水磷铈石以富铈为特征,并未产生铈的分异作用,因此将其作为缺氧环境的证据是有问题的.     

离子型稀土矿柱浸过程氨氮平衡及尾矿氨氮形态转化研究

离子型稀土矿柱浸过程氨氮的平衡与迁移转化研究可以对浸矿剂硫酸铵用量的模拟运算提供理论参考。试验以定南某离子型矿土为对象,采用室内柱浸模拟的方式对离子型稀土原矿氨氮的分布、硫酸铵浸矿过程氨氮平衡及尾矿氨氮赋存转化的影响进行了试验。结果发现,离子型稀土原岩风化过程中,还可能伴随着离子相铵盐的生成,在浸矿过程中会伴随稀土一起被浸出,离子相铵盐含量随离子相稀土含量的升高而增加。硫酸铵柱浸过程中残留在尾矿内的氨氮量与浸出液中的氨氮量占比分别为50.76%和49.24%,浸矿剂中半数铵根主要起到保持浸矿过程中铵根浓度的作用,在浸矿后会随浸出液流出。离子型稀土尾矿水溶态和可交换态氨氮在矿土含水率的影响下会发生可逆转化,在尾矿矿土自然风干过程中,尾矿内水溶态氨氮含量占比由63.24%降至32.01%,离子型稀土尾矿水溶态与可交换态氨氮的赋存含量需要前置时间和矿土含水率等条件才能准确定义。     

乌江流域沉积岩风化过程中稀土元素的富集与释放

以乌江流域石灰岩、白云质灰岩、白云岩、硅质岩、页岩和砂岩等沉积岩的13条风化剖面为对象，运用R型分层聚类分析和质量平衡计算方法，研究了这些岩石风化过程中稀土元素（REE）的富集与释放及其对植物生长和河水REE分布的影响，目的是为河水物质来源研究和为农业生产提供依据。结果表明：（1）乌江流域石灰土中REE的富集程度显著高于各自母岩、黄壤、上陆壳（UCC）、中国土壤（CS）和世界土壤（WS）；（2）沉积岩风化过程中REE的富集特征和机制可能与母岩中REE分布特征以及风化剖面中有机质、铁（氢）氧化物和粘土矿物的吸附有关；（3）沉积岩风化过程中释放的REE可为植物吸收利用；（4）石灰岩等沉积岩风化过程中REE和F。等元素的释放对河水溶解态REE的分布有重要影响。     

离子型稀土矿放射性核素迁移及处理研究进展

离子型稀土矿伴生一定量的铀、钍等天然放射性核素。采用原地浸矿工艺提取稀土时,部分放射性核素与稀土元素一同浸出,并随着稀土的冶炼过程富集在多种工序产生的废渣中,使得铀、钍、镭的放射性活度浓度大于1000 Bq·kg^-1,属于低放射性废渣。随着渣量的不断增加,该类低放射性废渣的安全处置已成为困扰行业发展的难题。本文阐述了中国对放射性辐射环境管理、放射性废物存储及处理要求的发展过程,总结了放射性核素铀、钍、镭在离子型稀土矿冶炼过程中的迁移富集规律,综述了溶剂萃取法、吸附法处理含放射性废水以及废渣资源化、减量化处理等方面的研究进展,分析了离子型稀土矿放射性核素处理存在的问题,最后提出了在放射性核素的源头减量化、废渣资源化、残渣安全化处置等方面的一些技术发展建议。     

浅谈腾冲地块与稀土矿有关的岩浆岩成矿专属性

目前,腾冲地块已初显国家级稀土矿战略后备基地雏形,但整体研究程度仍偏低,稀土矿床的成矿规律、成矿模式等方面的研究趋于空白。在前人研究的基础上,结合近年稀土矿勘查工作成果,通过研究腾冲地块不同时代、不同岩性的岩浆岩与稀土矿产出关系,取得以下认识:腾冲地块稀土矿床(点)成矿母岩时代有三叠纪(印支期)、白垩纪(燕山期)、古近纪和第四纪(喜马拉雅期),以古近纪(喜马拉雅期)为主;岩石类型有二长花岗岩、花岗斑岩、钾长花岗岩、英云闪长岩等,以二长花岗岩为主;成矿母岩都具有高硅(68%～78%)、富铝(12%～15%)、富碱(W_B(K_2O+Na_2O)值7.5%～10.6%,多数大于8%)、富钾(钾大于钠)特征,且稀土元素丰度较高;以轻稀土矿为主,仅有个别重稀土矿。腾冲地块发育有轻稀土矿与重稀土矿成矿母岩,具有得天独厚的稀土成矿条件,仍具有较大的找矿潜力。在今后地质工作中,应提高重视加强对稀土矿找矿勘查工作,尤其是古近纪岩体分布区、重稀土矿成矿母岩分布区,如陇川—盈江、新岐、古永地区。同时,对已发现的锡矿、铁矿等矿床,综合评价其花岗岩风化壳型稀土矿。     

江西武山块状硫化物矿石表生风化过程中稀土元素地球化学行为

The behavior of REE during the sulphide weathering is still poorly understood, although REE geochemistry during weathering of igneous rocks has been well documented, in this study, the REE contents of primary sulphide and their weathering products （gossan） of the Wushan copper mine were investigated. The mobility of REE in the weathering profile of sulphide is limited, with the majority of REE retained in the gossans. However, REE are fractionated in the weathering process, with HREE relatively enriched in the gossan samples. Ce is depleted in the gossan, whereas the difference of Eu anomaly of the gossan and primitive sulphide is neglectable.     

个旧超大型锡多金属矿稀土元素地球化学特征

对比研究了个旧不同类型岩(矿)石(蚀变花岗岩、钙质泥岩、大理岩、矽卡岩矿石、层状矿石和脉状矿石)的稀土元素、微量元素地球化学特征,借以示踪不同类型矿床的成矿物质来源。研究表明不同类型矿石中的稀土元素配分曲线较为相似,成矿物质具有同源性,并与本区的花岗岩具有一定的成因联系。由于其成矿方式的不同,不同类型矿石中的稀土元素特征和矿物组合特征略有差异,脉状矿石和层状矿石中稀土含量相对较少且富集轻稀土,而矽卡岩矿石中稀土含量相对较多且轻、重稀土的含量变化较大。     

花岗岩风化壳稀土存在形态分析方法研究

研究了一个测定花岗岩风化壳中REE存在形态的方法。以0.2 mol/L MgCl_2,2.5 mol/LHCl,0.5 mol/L NaOH及含15%H_2O_2的2.5 mol/L HCl连续提取风化壳试样中的稀土。经X射线衍射、红外光谱及剖面试样测试,论证了每一提取态的内涵,提出了花岗岩风化壳中非原生矿物相稀土存在活性态、铁铝共沉淀态和有机结合态的新认识。     

Alpha emitters from uranium mining in the environment

Uranium mining and milling activities usually generate an enhancement of radionuclide concentrations in the environment that may cause increased radiological exposure to mankind. For risk assessment and radiological protection of man and environment in these areas, usually, it is needed to implement radiological surveillance of water, soils, agricultural products, aerosols, and mining waste discharges as well. Radionuclides to be monitored in priority are alpha-emitting nuclides of the uranium natural series. Radioactivity analysis of materials from uranium mining areas of Portugal shows departure from secular radioactive equilibrium amongst uranium series radionuclides, thus rendering invalid the assumption of equilibrium and requiring the actual determination of each radionuclide. Radionuclide measurements performed with high resolution alphaspectrometry, as reported herein, produce accurate results on specific radionuclides that are essential in computing radiation doses to critical groups of the population.     

吉林夹皮沟金矿带的稀土元素地球化学研究

为了解吉林夹皮沟金矿带的成矿期次,利用稀土元素的示踪性,对夹皮沟金矿带含矿石英脉、花岗岩及变质地层斜长角闪岩等21个样品进行稀土元素含量测定。测定结果表明,石英脉ΣREE=19.12×10-6～147.57×10-6,δEu=0.61～1.22,平均值0.89,具弱的负Eu异常;太古代花岗岩ΣREE=121.40×10-6～157.32×10-6,δEu=0.87～1.09;中生代花岗岩ΣREE=69.78×10-6～90.95×10-6,δEu=0.94～1.02,LREE/HREE比值分别为11.51～14.12和14.16～16.73,后者轻重稀土分馏程度略高于前者;变质围岩ΣREE=22.40×10-6～275.86×10-6,δEu=0.75～5.79,平均值2.30,具明显的正Eu异常。三者都具有轻稀土富集的平滑稀土配分模型。结合其区域地质背景、流体包裹体和稀土元素特征,得出夹皮沟金矿存在两期成矿作用,分别对应于太古代成矿花岗岩岩浆作用及中生代燕山期花岗岩岩浆作用。太古代首次富集成矿,中生代燕山期叠加成矿并扩大成矿规模,成矿时代分别为2475～2469 Ma和170～160 Ma;结合稀土特征研究及包裹体研究,成矿流体以岩浆热液流体为主,遭受轻微地层变质热液混染,中生代成矿流体混染作用更强烈。     

Influence of hydrothermal wood degradation products on the uranium adsorption onto metamorphic rocks and sediments

The influence of highly functionalized saccharic and phenolic polymers that are formed in the process of hydrothermal wood degradation on the uranium(VI) adsorption onto metamorphic rocks and sediments from the Saxon uranium mining sites Schlema-Alberoda and Königstein was investigated in a laboratory study. Uranium(VI) adsorption from a simulated mine water takes place on the majority of rocks and sediments such as granite, gneiss, basalt, sandstone and clay marl. Exceptions are phyllite and clay stone that do not bind any uranium from the mine water. Polymeric wood degradation products such as fragments of celluloses and lignin increase the uranium(VI) adsorption whereas the presence of saccharic and phenolic monomers (vanillic acid and gluconic acid) leads to a lower adsorption.     

Separation of uranium from iron in ground water samples using ion exchange resins

Uranium determination in environmental samples is faced with problems due to presence of iron and other major elements. Iron is also used many a times for pre-concentration of uranium and actinides. Separation of milligram quantity of Fe from microgram quantity of uranium becomes essential during the estimation step. A simple two step procedure has been standardized for separating uranium and iron using anion exchange in 0.025 M H₂SO₄. Quantitative recovery of uranium was obtained as well as good separation from iron. This method was applied for estimation of uranium in water samples.     

Distribution pattern of REE and other elements in the host rocks of the Gubrunde uranium occurrence,NE Nigeria

Prospecting for high grade uranium deposits in NE Nigeria has over the years among other reasons been handicapped by lack of adequate understanding of the elemental primary dispersion pattern associated with known occurrences in this region. Thirty six samples from a low grade uranium occurrence at Gubrunde consisting of disseminated ores and hostrocks were therefore analyzed for 38 elements by NAA, DNAA, EDXRF and flame AAS techniques. The analytical data were evaluated using multivariate statistical techniques. The results show three element groupings (associations). The first group consists of Pb, Ba, Ce, Sm (LREE), that are enriched with increasing uranium concentration in the mineralized zone and are therefore capable of serving as pathfinder elements for uranium. The second group comprising of MgO, K₂O, CaO, Na₂O and the HREE are depleted in the mineralized zone due to action of hydrothermal fluids and are indicative of altered/mineralized rocks. The third group consists of the rest bulk of elements which feature little or no significant enrichment with increasing uranium but associate with ferruginization (haematite) and possibly refractory minerals.     

Method of separating uranium from iron and thorium

Acid leaching of uranium deposits is not a selective process. Sulfuric acid solubilizes iron(III) and half or more of the thorium depending on the mineralog of this element. In uranium recovery by solvent extraction process, uranium is separated from iron by an organic phase consisting of 10 vol% tributylphosphate(TBP) in kerosine diluent. Provided that the aqueous phase is saturated with ammonium nitrate or made 4–5 M in nitric acid prior to extraction. Nitric acid or ammonium nitrate is added to the leach solution in order to obtain a uranyl nitrate product. Leach solutions containing thorium(IV) besides iron are treated in an analogous fashion. Uranium can be extracted away from thorium using 10 vol% TBP in kerosine diluent. The aqueous phase should be saturated with ammonium nitrate and the pH of the solution lowered to 0.5 with sufficient amount of sulfuric acid. In other words, the separation of uranium and thorium depends on the way the relative distributions of the two materials between aqueous solutions and TBP vary with sulfuric acid concentration. Thorium is later recovered from the waste leach liquor, after removal of sulfate ions. Uranium can be stripped from the organic phase by distilled water, and precipitated as ammonium diuranate.