Geochemical characteristics of acid mine drainage and sediments from coal mines, Shanxi Province, China

In this study, geochemical characteristics of acid mine drainage （AMD） and its sediments from the Malan and Sitai coalmines, Shanxi Province, China, were investigated. Many analytical approaches such as IC, ICP-MS, XRD, XRF, and modeling calculation of hydrogeochemistry using PHREEQCI software were employed. The AMD is characterized by higher concentrations of iron and sulfate, a low pH, and elevated concentrations of a wide variety of heavy metals. The results of modeling calculation by PHREEQCI software demonstrate the metals in AMD are present mainly as Me^n＋ and MeSO4^n-2 species. The sediments of AMD are composed mainly of iron-beating minerals such as goethite and schwertmannite, which are controlled by pH, Fe and SO4^2- concentrations. The schwertmannite mineral has been found for the first time in China.     

陈家山矿煤中微量元素和稀土元素地球化学特征

通过对陈家山煤矿中下侏罗统延安组4^#主采煤层中微量元素和稀土元素的测试分析,发现煤中富集亲花岗岩的钨钼族元素W、Mo、Bi、Sn、Ba、Sr和Li,说明该区煤系形成期间的陆源碎屑主要来自花岗岩和花岗片麻岩等中、酸性岩石。4^#煤中ΣREE平均值为98.2×10^-6,稀土元素分布模式十分相似,呈左高右低的宽缓“V”型曲线,Eu负异常明显,反映出稀土元素与陆源碎屑岩关系密切,成煤期间稀土元素来源一致,陆源物质的供应相对稳定。     

淮南采煤沉陷区表层沉积物稀土元素地球化学特征

稀土元素由于其独特的化学特征被广泛应用于环境地球化学分析过程研究。以淮南采煤沉陷区表层沉积物中稀土元素(REEs)为研究对象,采集研究区潘一、顾桥、谢桥沉陷区的表层沉积物样品共12个,采用ICP-MS对样品的稀土元素含量进行测试分析,探讨了表层沉积物中稀土元素的含量分布特征、控制因素及其物质来源。结果表明:研究区表层沉积物中稀土元素含量为54.63~130.45 μg/g,平均102.60 μg/g;LREE/HREE比值为11.89~20.55,平均14.29,轻稀土呈现明显富集现象;相关性分析结果显示,REEs趋向于黏土组分中富集;研究区养殖和捕捞活动导致表层沉积物中稀土元素含量的降低;球粒陨石标准化结果表明,研究区稀土元素呈现不同程度的La和Gd正异常,其中,Gd正异常主要是受到燃煤的影响,而La正异常主要与燃煤和化肥有关。结合Pearson相关性、球粒陨石标准化和(La/Yb)_N-(La/Sm)_N-(Gd/Yb)_N三元图判别,认为研究区水体表层沉积物中稀土元素与人类活动(燃煤和化肥)有关,研究认识为污染物的源头控制和煤矿区环境的生态治理提供参考依据。      

State of rare earth elements in the rare earth deposits of Northwest Guizhou,China

We studied the states of rare earth elements in ore of the Xianglushan rare earth deposit. Rare earth ore samples were tested and examined by scanning electron microscope, electron probe, and chemical leaching. No independent rare earth minerals were detected by scanning electron microscope. Elements detected by the electronic probe for the in situ micro-zone of the sample included: O, Al, Si, Ca, Mg, Fe, Ti, K, Na, S, Cl, C, Cu, Cr, V, and Pt. Rare earth elements were not detected by electron probe. (NH4)₂SO₄, (NH₄)Cl, NaCl, and H₂SO₄ were used as reagents in chemical leaching experiments that easily leached out rare earth elements under the action of 10% reagent, indicating that the rare earth elements in ore are mainly in the ionic state rather than present as rare earth minerals.     

Geochemistry of rare earth elements in a marine influenced coal and its organic solvent extracts from the Antaibao mining district, Shanxi, China

Twenty-six samples including roof, bottom and coal plies of a marine influenced coal bed were collected from the Antaibao mining district, Shanxi, China. The rare earth elements (REEs) were determined in solids and organic solvent extracts. The distribution pattern showed three distinct patterns: shale-like, LREE-rich and HREE-rich. This is attributed to the variable microenvironment of peat-forming swamp, the degree of marine influences and different REE sources. REEs in the coal are mainly controlled by detrital minerals but also affected by seawater. The chondrite-normalized REE patterns of the organic solvent extracts are distinctly different from those of corresponding original coal samples, which show a negative Eu anomaly, a depletion of middle REEs and an enrichment of HREEs. The LREEs in coal extracts are likely adsorbed by hydrogen-containing functional groups, and HREEs are likely bonded to carbon atoms.     

Dissolved rare earth elements in river waters draining karst terrains in Guizhou Province,China

Winter seasonal concentrations of dissolved rare earth elements (REE) of two major river systems (the Wujiang River system and the Yuanjiang River system) in karst-dominated regions in winter were measured by using a method involving solvent extraction and back-extraction and subsequent ICP-MS measurements. The dissolved REE concentrations in the rivers and their tributaries are lower than those in most of the large rivers in the world. High pH and high cation (i.e., Na⁺ + Ca²⁺) concentrations of the rivers are the most important factors controlling the concentrations of dissolved REE in the river water. The dissolved load (<0.22 μm) REE distribution patterns of high-pH river waters are very different from those of low-pH river waters. The shale (PAAS)-normalized REE patterns for the dissolved loads are characterized by light REE-enrichment and heavy REE-enrichment. Water in the upper reaches of the Wujiang River generally shows light REE-enriched patterns, while that in the middle and lower reaches generally shows heavy REE-enriched patterns. The Yuanjiang River is heavy REE enriched with respect to the light REE in the same samples. Water of the Wuyanghe River draining dolomite-dominated terrains has the highest heavy REE-enrichment. Most river water samples show the shale-normalized REE patterns with negative Ce and Eu anomalies, especially water from Wuyanghe River. Y/Ho ratios show that the water/particle interaction might have played an important role in fractionation between HREE and LREE.     

淮北煤田煤的稀土元素地球化学

采用仪器中子活化分析法（ＩＮＡＡ）测试了淮北煤田６、３煤层１个煤样的稀土元素含量,并探讨了稀土元素地球化学特征,得出以下认识：１１个样吕的平均ΣＲＥＥ为８１．９５３５ｕｇ／ｇ;稀土元素分布模式呈左高右低的、具Ｅｕ负异常的“Ｖ”型曲线。相关分析、聚类分析的结果表明：稀土元素与灰分、陆源碎屑的元素（Ｓｉ、Ａｌ、Ｔｉ、Ｃｒ、Ｃｏ、Ｎｉ、Ｔｈ、Ｔａ、Ｓｃ和Ｒｂ等）的关系密切,而与海相元素（Ｃａ、Ｓｒ等）关     

晋北中高硫煤中稀土元素的地球化学特征

应用中子活化分析方法，测定了晋北两层中高硫煤中稀土元素的含量。通过对稀土元素的分布模式，相关分析和聚类分析的研究，得出如下认识；成煤环境对稀土元素的含量具有控制作用。但中高硫煤中稀土元素总量会受到沉积期后酸性溶液下渗淋滤作用的影响；同一煤层中各分层的稀土元素应具有基本相同的分布模式，异常的稀土元素分布模式指示了沉积期后地质作用的影响；煤中稀土元素的主要赋存状态为无机相，主要来源为陆源碎屑矿物；煤中与稀土伴生的有害元素有V，P，Mo,Cr,Cu,Mo,Th和Cd等，在加工洗选过程中有洁净潜势。     

Effect of simulated acid rain on soil acidification and rare earth elements leaching loss in soils of rare earth mining area in southern Jiangxi Province of China

Acid rain has long been a great concern because of environmental and ecological problems; however, the effect of acid rain on soil acidification, loss of rare earth elements (REEs) via the leaching process, and transformation are rarely reported in rare earth mining areas. Through a simulated acid rain leaching experience, the effect of acid rain was studied on soil acidification and REEs leaching loss. The results showed that the tested soil had certain buffering capacity against nearly neutral rainwater. However, simulated acid rain of low and very low pH (pH ≤ 3.5) had a greater impact on soil acidification. After eluviating by simulated acid rain of pH 3.5 for 36 h, the pH of tailings, garden soil, paddy soil, and alluvial soil decreased by 20.41, 32.03, 13.60, 16.88, and 15.83 %, respectively, from the original values. For simulated acid rain of pH 2.5, it was 31.89, 44.76, 31.26, 29.87, and 29.15 %, respectively. After simulated acid rain eluviations of low and very low pH (pH ≤ 3.5), the order of the leaching rate of REEs in the tested soil was as follows: garden soil > tailings > paddy soil > alluvial soil. For nearly neutral rainwater (pH 4.5 simulated acid rain and pH 5.6 deionized water), the order was tailings > garden soil > paddy soil > alluvial soil. For simulated acid rain of the same pH, the leaching amounts of REEs in tailings and garden soil were higher than those in paddy soil and alluvial soil. After leaching by low and very low pH-simulated acid rain (pH ≤ 3.5), the peak value of the leaching amount of REEs in all tested soil appeared at 2 h, and then gradually reduced and reached a stable leaching state 20 h after leaching. On leaching by simulated acid rain of pH 2.5, the maximum REEs contents of leachate in tailings, garden soil, paddy soil, and alluvial soil were 156.35, 145.82, 99.88, and 85.97 mg/L, respectively. For pH 3.5 of simulated acid rain, it was 130.49, 110.49, 80.57, and 62.73 mg/L, respectively. On leaching by simulated acid rain of pH 4.5, the maximum contents of REEs in the leachate were 53.46 and 29.82 mg/L, respectively, which were observed after leaching for 6 h in tailings and garden soil that became stable 12 h after leaching. The contents of leached REEs in paddy soil and alluvial soil were always in a lower and stable state. After eluviations with deionized water of pH 5.6, the contents of leached REEs in other soils were lower, except for the slight fluctuations in tailings. The maximum content in the leachate of REEs was in the water-soluble and exchangeable fraction. When bound to carbonate fractions, REEs were not detected in the leachate. REEs bound to iron-manganese (Fe–Mn) oxides fraction and to organic matter fraction in the leachate possibly came from the tested soil or from the REEs transformation during the migration process. The content of residual fraction REEs in the leachate was very low.     

山西沁水煤田首阳山矿15#煤的稀土元素分布规律、赋存状态及其对成煤环境的指示

文章以沁水煤田长治首阳山矿15号煤为研究对象,运用电感耦合等离子体质谱(ICP-MS)和X射线荧光光谱(XRF)等方法对煤中的稀土元素进行测试和分析。探讨了15号煤中稀土元素的富集机理、配分模式、赋存状态以及成煤环境等地球化学特征。结果表明:(1)研究区煤层中的稀土元素含量均值为49.28μg/g,整体含量较低;(2) 15~#煤(除SYS15-2外)和夹矸中稀土元素均为轻稀土富集型(LREY),并且夹矸中轻稀土富集更加明显;(3)稀土元素主要赋存在黏土矿物中;(4)成煤环境整体上以弱还原环境为主,稀土元素物质来源主要为陆源碎屑。     

Behavior of the rare earth elements in the Oklo natural reactor

A systematic analysis of the abundance and isotopic composition of ten REE (and Ba) in a sample from the reactor zone at the Oklo (Gabon) ore deposit is presented. From this analysis some constraints on the behavior of the REE group during and after the reaction time are determined. Taking into account the complex state of this sample, the main characteristics of the reactor are deduced.From the abundances of isotopes with large neutron capture cross sections the amount of REE (supposed to be natural) added after the reaction time is calculated first. The comparison of the fluence values obtained respectively from the analysis of the Nd and Dy isotopic spectrum indicates a rather good stability of the REE group during the reaction time. The total number (²³⁵U)_f of ²³⁵U nuclei that fissioned during the reaction calculated from different elements of the REE group provides an indication on the relative migration of these elements since the reaction time. Results of these computations suggest a migration of the heavy REE relative to the light REE to outside the reaction zone. As a consequence of these deductions on the behavior of the REE in the Oklo ore, the light REE appear the most appropriate to study the characteristics of the reactor. The reactor characteristics we deduced from this sample (fluence, epithermal index, proportion of nuclides that fissioned, duration of the reactor) are within the range of the ones determined in other studies dealing with REE analysis.     

山西省煤系伴生三稀矿产资源研究现状及找矿前景

为进一步勘探和开发山西省煤系伴生的稀有、稀土、稀散元素（简称三稀元素）矿产资源,在综合以往研究的基础上,统计了山西省煤系伴生三稀元素的含量和赋存特征,同时结合山西省煤炭资源分布特征探讨了煤系伴生三稀矿产资源的找矿前景。结果表明,山西省宁武煤田平朔矿区为煤系伴生锂超大型矿床,北部煤炭基地部分矿区和西山煤田部分矿区具备煤系伴生锂成矿潜力;宁武煤田北部、大同煤田北部、河东煤田北部及西山煤田局部地区具备煤系伴生镓成矿潜力;沁水煤田和西山煤田山西组含煤岩系的伴生稀土元素均有一定的工业开发利用价值;省内六大煤田含煤岩系中尚未发现其他达到工业利用品位的伴生三稀元素矿床。初步研究成果对指导山西省煤系伴生矿产资源开发、煤炭资源可持续发展和粉煤灰高效利用具有实际意义。     

巢湖的稀土元素地球化学特征

采用液-液萃取法和ICP-MS测试技术对巢湖的溶解态稀土元素进行了分析。结果表明,巢湖的溶解态稀土的含量与世界淡水相当,丰水期的样品含量高于其他季节。pH值和悬浮物、胶体是控制巢湖水体中溶解态稀土含量的主要因素。巢湖的溶解态稀土的分布模式以平坦型为主,少数呈现重稀土富集。丰水期和枯水期的溶解态稀土的(La/Yb)N值从西半湖区到东半湖区呈现有规律性的逐渐增大,并且丰水期的(La/Yb)N值低于枯水期。在富营养化湖泊中,胶体和水生生物可能是造成这一现象的主要原因。     

Mineralogical control of rare earth elements in acid sulfate soils

Major, trace and rare earth element concentrations were measured in porewater, surface water and sediments at an acid sulfate soil site. The concentrations of La and Ce in porewater are up to 1-3 ppm. There is a strong correlation between REE concentration and acidity, except that the maximum concentrations were consistently found below the horizon of maximum acidity, associated with an increase in pH (to ca. 4) and change in mineralogy from jarosite-dominated to goethite-dominated mottles. Jarosite replacement by goethite is as expected with the rise in pH, which in turn is due to the occurrence of a fossil shell bed just below. The rare earth element patterns in the porewaters are enriched in the MREE with respect to Post-Archaean Australian Shale (PAAS). Measurements and calculations show that this is in accord with experiments on low-degree partial dissolution of jarosite, even when the jarosite itself is highly enriched in LREE. There is a clear fractionation in the patterns between the clay-rich soil matrix, which is slightly depleted in the LREE when normalized to PAAS (La/Yb_PAAS ∼0.5), and the secondary mineral phase jarosite, which is enriched in the LREE (La/Yb_PAAS = 15-50). The REE pattern in the porewater changes with the transition from jarosite- to goethite-rich mottles, becoming relatively more enriched in the LREE compared to the HREE, which is consistent with the incongruent dissolution of jarosite to form goethite and the release of greater amounts of jarosite REE to solution, including proportionately more of the jarosite-compatible LREE.Maximum surface water REE concentrations in acidic water were 100-200 ppb La and Ce. REE patterns in surface water were very similar to the porewater transition zone, enriched in the MREE, but asymmetric, relatively enriched in the LREE compared to the HREE.     

Evaluation and zoning of groundwater hazards in Pingshuo No. 1 underground coal mine,Shanxi Province,China

Coal mining safety has been compromised with water inrushes from aquifers either overlying or underlying the coal seams. Detailed studies of the associated hydrogeological conditions in China have led to different approaches to mitigate the water inrush risks from these two types of aquifers—the ‘three diagram method’ for overlying-aquifer water inrushes and the ‘vulnerability index method’ for underlying-aquifer water inrushes. The ‘three diagram method’ consists of: (1) aquifer water-abundance distribution charts derived from a geographic information system and analytic hierarchy process based water-abundance index model; (2) a fracture height map showing mining-induced fractures above the coal seam, established with stratified numerical simulations; and (3) a comprehensive partition map identifying the overlying-aquifer water inrush risk. The ‘vulnerability index method’ uses site-specific data to establish thematic maps for major factors that affect the underlying-aquifer water inrushes, whereas the weight of each control factor is determined by the analytic hierarchy process. The calculated vulnerability index is indicative of water inrush risks. The effectiveness of these methods is illustrated with a case study at the Pingshuo No. 1 underground coal mine, Shanxi Province, China.     

Concentrations of rare earth elements in topsoil from East China

Fifty topsoil samples collected from 12 different regions of East China have been analyzed for rare earth elements (REEs). The average REE concentrations of the 50 topsoil samples are much higher than world average and are characterized by LREE-enrichment, HREE-depletion, Eu-depletion and Ce-enrichment. However, the REE concentration is not strongly affected by the climate of the sampling site; it is controlled mainly by parent materials. The plot of Ce/Eu against Eu/Sm is proved to be useful to distinguish different parent materials of topsoil. Each element in the 50 topsoil has a good correlation with its neighboring element. Seven of the 13 values are above 0.987.     

鄂尔多斯盆地西缘煤中稀土元素特征

煤中稀土元素是煤地质领域研究源岩和沉积环境的良好地球化学指示剂,也是一种重要的矿产资源。运用ELEMENT XR等离子体质谱分析仪对鄂尔多斯盆地西缘石炭-二叠系和侏罗系延安组煤样中稀土元素进行测试,计算了多种化学参数并绘制了稀土元素分布类型曲线。在对稀土元素（REY）的地球化学特征分析的基础上,探讨了其物质来源。结果表明,石炭-二叠系煤中REY含量明显高于中国和世界煤中的均值,也高于上地壳值,呈铕（Eu）负异常,铈（Ce）负异常,这可能因为石炭-二叠系处于海陆交互相,与其处于强的还原环境有关;而侏罗系煤中REY含量却低于中国和世界煤中的均值,也低于上地壳值,呈轻微Eu负异常,轻微Ce正异常,侏罗系延安组主要为氧化的陆相环境,所以δCe在煤中的不亏损才会普遍存在。通过煤中稀土元素的分配模式、平面展布与其构造环境的综合分析,推测石炭-二叠系的物源为研究区西北部的阿拉善地块和北部的阴山古陆,南部的秦-祁造山带为侏罗系煤中稀土元素提供了主要的物质来源。     

龙感湖稀土元素的地球化学特征

采用液-液萃取法,连续提取法和ICP-MS测试技术,对龙感湖不同季节水和颗粒物中稀土元素进行研究.结果表明,龙感湖的溶解态稀土含量极低,稀土总含量(ΣREE)在3.14～129.81ng/kg之间,且季节性变化明显.龙感湖溶解态稀土元素表现出平坦型的页岩配分模式,这是由于在草型湖泊中溶解态稀土主要以吸附在微细胶体上的形式存在,水粒相互作用在这个过程中起主要控制作用.悬浮物中的稀土含量顺序为:残渣态>>Fe-Mn结合态>>有机态和AEC态,颗粒物中稀土元素主要以残渣态形式存在.Fe-Mn结合态、有机态和AEC态的页岩配分模式为中稀土富集,残渣态的页岩配分模式为平坦型.这说明中稀土与轻重稀土相比具有更强的潜在地球化学活性,但在龙感湖的环境中的迁移能力相对轻重稀土来说较弱.     

昆阳磷矿中稀土元素赋存状态研究

对昆阳磷矿中稀土元素的赋存状态进行了系统研究,结果表明矿体中稀土元素总量在50×10-6～250×10-6之间,以轻稀土元素富集、重稀土元素亏损为特征,Y含量在30×10-6～155×10-6之间,稀土元素总量与胶磷矿含量呈正相关关系。重砂矿物查找结果显示,昆阳磷矿中缺乏独立的稀土矿物。物相分析结果表明,稀土元素主要赋存在胶磷矿中,碳酸盐相和硅酸盐相中稀土元素含量极低。LA-ICPMS测试结果表明,胶磷矿单矿物中稀土元素总量在280×10-6～420×10-6之间,而白云石单矿物中的稀土元素总量均低于10×10-6。综合分析结果表明,昆阳磷矿中的稀土元素应主要以类质同像的形式存在于胶磷矿中。     

Fractionation of rare earth elements in the acid treatment of granitoids

The relative enrichment of authigenic clay minerals with heavy rare earth elements (HREE) in Paleoproterozoic weathering profiles on the Baltic Shield is related to the presence of strong acids in drainage water. This is confirmed by the results of laboratory experiments on the treating granitoids by sulfuric acid solutions. Solutions obtained in the experiments exhibit the prevalence of potassium over sodium, whereas the concentration of potassium and sodium in initial granitoids is nearly the same.