共查询到20条相似文献，搜索用时 26 毫秒
1.
The efficiency of neutron activation as an analytical technique has been evaluated for exploration of lateritic and karstic bauxites in Sierra Leone, Guinea, Australia (Gove), Philippines and Jamaica. The 10-g bauxite samples are prepared in the field and sent to a central laboratory. With the “Automatic Bauxite Analyzer” — equipped with an isotopic neutron source — a single Al and Si determination can be made in 5 minutes. For calibration, standards are required which are similar in composition to the samples to be analyzed. Using sample pairs and averaging the results of three subsequent determinations an accuracy of ±2% Al2 O3 and about ±0.6% SiO2 can be obtained. Time requirements, accuracy and cost of this technique are compared with wet chemistry and X-ray fluorescence. For an exploration programme incorporating for example 15,000 drill core samples, a 50% reduction in expenditure for analytic determinations can be achieved by applying neutron activation instead of X-ray fluorescence alone. 相似文献
2.
3.
铝土矿中主成分的X射线荧光光谱分析 总被引：1，自引：1，他引：0
利用X射线荧光光谱法测定铝土矿中主成分A l2O3、SiO2、Fe2O3、TiO2。采用四硼酸锂-偏硼酸锂作熔剂,溴化锂作脱模剂,国产高频熔样炉高温熔融制备玻璃圆片,以标准物质制作校准曲线进行测定,并与化学法进行对照,结果基本一致。方法操作简单、快速,准确度和精密度均达到国家标准方法规定的要求,已用于实际生产中。 相似文献
4.
Due to the varying toxicity of different Al species, information about Al concentration and speciation is important when assessing water quality. Modelling Al speciation can support operational monitoring programmes where Al speciation is not measured directly. Modelling also makes it possible to retroactively speciate older samples where laboratory fractionation was not undertaken. Organic-rich waters are a particular challenge for both laboratory analysis and models. This paper presents the modelling of Al speciation in Swedish surface waters using the Windermere Humic Acid Model (WHAM). The model was calibrated with data from operational monitoring, the Swedish national survey of lakes and rivers, and covers a broad spectrum of physical and chemical conditions. Calibration was undertaken by varying the amount of DOC active in binding Al. A sensitivity analysis identified the minimum parameters required as model input variables primarily to be total Al, organic C, pH, F−, and secondly Fe, Ca and Mg. The observed and modelled Ali had no significant differences (Spearman rank, p < 0.01), however, lake samples modelled better than rivers. Samples were placed in the correct toxicological category in 89–95% of the cases. The importance of the size of the calibration data set was assessed, and reducing the calibration data set resulted in poorer correlations, but had little impact on the toxicological placement. Overall, the modelling gave satisfactory results from samples covering a broad spectrum of physical and chemical conditions. This indicates the potential value of WHAM as a tool in operational monitoring of surface waters. 相似文献
5.
Naomi AOTA Yutaka MIYAMOTO Sakae KOSANDA Yasuji OURA Toshiyuki OKUI Koh SAKAMOTO 《Geostandards and Geoanalytical Research》1994,18(2):185-193
Nine rock reference samples "Sedimentary rock series" issued by the Geological Survey of Japan (GSJ) were analysed for up to 31 elements by neutron activation analysis (NAA); 14MeV-NAA for Si and Al, fission track method for U, radiochemical and instrumental NAA for rare-earth elements, and instrumental NAA for the remaining elements, with reactor neutrons for the latter three. The present results are compared with reported values. 相似文献
6.
贵州修文小山坝铝土矿中稀土元素地球化学特征 总被引：11，自引：0，他引：11
前人已经积累了大量贵州铝土矿的研究成果,但关于铝土矿与其中稀土元素的关系至今不清。本研究以修文小山坝铝土矿为例,通过ICP-MS分析测试,研究了矿石和围岩的稀土元素组成。结果表明,矿石中稀土配分模式为轻稀土富集向右倾斜型,具明显Eu负异常,与下寒武统娄山关群含泥质白云岩稀土特征参数和配分模式相似,指出该矿床成矿物质来源以下寒武统娄山关群含泥质白云岩为主,在相对氧化环境下经风化作用成矿。矿床中稀土元素主要富集于矿体及其周围,与Al2O3含量具正相关关系。矿石中稀土元素含量大多达到或超过综合利用标准,具有巨大的潜在经济价值。 相似文献
7.
Naomi AOTA Yutaka MIYAMOTO Sakae KOSANDA Yasuji OURA Koh SAKAMOTO 《Geostandards and Geoanalytical Research》1994,18(1):65-84
Fifteen rock reference samples "Igneous rock series" issued by the Geological Survey of Japan were analysed for up to 31 elements by neutron activation analysis (NAA); 14 MeV-NAA for Si and Al, fission track method for U, radiochemical and instrumental NAA for rare-earth elements, and instrumental NAA for the remaining elements, with reactor neutrons for the latter three. The present results are compared with published values. 相似文献
8.
An Investigation of Digestion Methods for Trace Elements in Bauxite and Their Determination in Ten Bauxite Reference Materials Using Inductively Coupled Plasma‐Mass Spectrometry 
下载免费PDF全文
下载免费PDF全文 Wen Zhang Liang Qi Zhaochu Hu Cunjiang Zheng Yongsheng Liu Haihong Chen Shan Gao Shenghong Hu 《Geostandards and Geoanalytical Research》2016,40(2):195-216
Trace elements from samples of bauxite deposits can provide useful information relevant to the exploration of the ore‐forming process. Sample digestion is a fundamental and critical stage in the process of geochemical analysis, which enables the acquisition of accurate trace element data by ICP‐MS. However, the conventional bomb digestion method with HF/HNO3 results in a significant loss of rare earth elements (REEs) due to the formation of insoluble AlF3 precipitates during the digestion of bauxite samples. In this study, the digestion capability of the following methods was investigated: (a) ‘Mg‐addition’ bomb digestion, (b) NH4HF2 open vessel digestion and (c) NH4F open vessel digestion. ‘Mg‐addition’ bomb digestion can effectively suppress the formation of AlF3 and simultaneously ensure the complete decomposition of resistant minerals in bauxite samples. The addition of MgO to the bauxite samples resulted in (Mg + Ca)/Al ratios ≥ 1. However, adding a large amount of MgO leads to significant blank contamination for some transition elements (V, Cr, Ni and Zn). The NH4HF2 or NH4F open vessel digestion methods can also completely digest resistant minerals in bauxite samples in a short period of time (5 hr). Unlike conventional bomb digestion with HF/HNO3, the white precipitates and the semi‐transparent gels present in the NH4HF2 and NH4F digestion methods could be efficiently dissolved by evaporation with HClO4. Based on these three optimised digestion methods, thirty‐seven trace elements including REEs in ten bauxite reference materials (RMs) were determined by ICP‐MS. The data obtained showed excellent inter‐method reproducibility (agreement within 5% for REEs). The relative standard deviation (% RSD) for most elements was < 6%. The concentrations of trace elements in the ten bauxite RMs showed agreement with the limited certified (Li, V, Cr, Cu, Zn, Ga, Sr, Zr and Pb) and information values (Co, Ba, Ce and Hf) available. New trace element data for the ten RMs are provided, some of which for the first time. 相似文献
9.
桂西田阳堆积型铝土矿矿物学及地球化学 总被引：1，自引：0，他引：1
[摘 要]桂西田阳堆积型铝土矿产于第四纪红土层中。本文通过对桂西田阳第四系堆积型铝土矿进行一系列矿物学与地球化学研究,探索铝土矿的物质来源。矿物学分析显示铝土矿石中主要矿物为硬水铝石、赤铁矿和锐钛矿,含有少量高岭石、鲕绿泥石、三水铝石、针铁矿、金红石、伊利石、蒙脱石和石英等。地球化学分析显示,组成铝土矿石的主要化学组分有Al2O3、Fe2O3、SiO2、TiO2、FeO 和H2O+;微量元素分析显示,铝土矿石相对地壳和原始地幔富集B、Li、Ga、Zr、Hf、Nb、Ta、W、Th、U 等元素,而亏损Ni、Cr 等元素。矿石中明显富集稀土元素,稀土总量变化大,轻重稀土分异明显,轻稀土元素富集明显;矿石具有明显的铈异常和铕异常,且铕异常相对稳定,为一致的负异常。元素相关性分析显示常量元素间相关性较差;部分微量元素如Zr、Hf、Nb 和Ta 间呈现出较高的正相关性。通过Zr/ Hf、Nb/ Ta 图解、Eu/ Eu* - TiO2/ Al2O3图解和Zr-Cr-Ga 图解综合分析显示铝土矿物质来源复杂,底板碳酸盐岩和周围火成岩都为铝土矿提供物源。 相似文献
10.
H. A. Das J. Zonderhuis H. W. van der Marel 《Contributions to Mineralogy and Petrology》1971,32(3):231-244
Scandium, aluminium and iron contents of a considerable number of rocks, minerals and sediments for various origin are given. They have been obtained by instrumental neutron activation analysis.The concentrations of these elements in rocks and minerals are very variable. However the Fe/Sc and Al/Sc ratios for the finer particles of sediments from different origins are fairly constant. At a spec. surf. of 100 m2/g is found 0.2 to 0.3 × 104 for Fe/Sc and 0.60 to 0.95 × 104 for Al/Sc (mol).In the coarser sediments there is a considerable influence of particle size. Consequently when Sc-contents of sediments are compared for classification purposes, their spec. surf. or granulometric composition should be determined as well. 相似文献
11.
Roles of adhered Paenibacillus polymyxa in the dissolution and flotation of bauxite: a dialytic investigation 总被引：1，自引：0，他引：1
Bio-related techniques have been proved to be efficient and specific in eliminating impure minerals such as goethite, hematite
and kaolinite from aluminum hydroxides in bauxite processing. In this study, the bacterium Paenibacillus polymyxa (P. polymyxa) mediated dissolution and flotation of bauxite were experimentally investigated. To disclose the contribution of adhered
bacteria to these two processes, comparative experiments were designed, with one (and the other not) being dialyzed to prevent
cells from contacting with bauxite. The results show that all the release rates of Al, Fe and Si are accelerated by the involvement
of bacteria during 11 experimental days. More Al, Si and especially Fe are leached out in contact trial than in dialysis trial,
and simultaneously, a large amount of Si-enriched flocs are formed. Further analysis indicates that with the adhesion of P. polymyxa and high molecular weight metabolites, Fe minerals are much more dissolvable than kaolinite. However, kaolinite can be floated
easily with the mediation of adhered bacteria and metabolites. This study suggests that in bauxite biobeneficiation, sufficient
contact between microbes and bauxite can facilitate the elimination of impurities such as iron and silicon. 相似文献
12.
定量遥感找矿是遥感大数据在找矿应用中的一项前沿技术。本文采用多元回归分析方法,通过对多组不同数量地表铝土矿样本进行遥感建模与反演实验,探索样本量对定量遥感建模的影响。实验中,首先以地表采样获得的Al2O3、SiO2含量分析结果作为样本数据,再根据样本位置从Landsat 8遥感数据中分别读取1~7个波段反射率数据,然后利用SPSS软件,将Al2O3、SiO2含量与相应的1~7波段反射率进行多元回归分析,并分别建立Al2O3、SiO2含量遥感定量反演模型。为了得到最佳反演模型,随机选出6批不同数量的样本进行建模实验,每批样本大约2/3用于建模,其余1/3用于模型检验。实验结果表明:随着样本量增加,模型的判定系数(R2)均呈先快速升高后缓慢下降的趋势,反演结果的均方根误差则与之相反。当样本量为50左右时,判定系数取得极大值,均方根误差取得极小值,总体具有偏态分布特征。最后,利用遥感影像对样本量为50时建立的模型进行反演验证,研究区地表Al2O3、SiO2含量的反演结果与实际情况吻合得很好,从而证实了该建模方法具有可靠性,可以进一步推广使用。 相似文献
13.
桂西地区铝土矿为典型喀斯特型,包括二叠系沉积型和第四系堆积型两亚类。堆积型铝土矿是沉积型铝土矿经抬升、破碎、风化,最后堆积于喀斯特洼地中形成。以平果教美铝土矿为研究对象,探索堆积型铝土矿形成过程中矿物的变化与元素迁移。沉积型矿石的矿物组成包括硬水铝石、鲕绿泥石、锐钛矿及少量针铁矿、金红石和高岭石;堆积型矿石的矿物组成主要为硬水铝石、锐钛矿、高岭石及少量三水铝石和鲕绿泥石。转化过程中堆积型矿石中的硬水铝石含量明显增加,鲕绿泥石含量明显减少。沉积型铝土矿的主要化学组成为Al2O3、SiO2、FeO和TiO2;堆积型为Al2O3、SiO2、TiO2和Fe2O3。两类矿石中元素Zr 、Ba、Nb、V含量均较高,稀土总量变化大,富集轻稀土。质量平衡计算表明堆积型铝土矿形成过程中Al、Ba、Sr、Y等元素增加,而Si、Fe、Ti、Nb、V、Ce等元素减少,其余元素变化不明显。 相似文献
14.
Comparison of Fused Glass Beads and Pressed Powder Pellets for the Quantitative Measurement of Al,Fe, Si and Ti in Bauxite by Laser‐Induced Breakdown Spectroscopy 下载免费PDF全文
下载免费PDF全文 Alexandrina A. C. Carvalho Victoria C. Alves Daniel M. Silvestre Flávio O. Leme Pedro V. Oliveira Cassiana S. Nomura 《Geostandards and Geoanalytical Research》2017,41(4):585-592
Due to matrix interference and sample particle size effects, some of the most important and difficult issues in laser‐induced breakdown spectroscopy (LIBS) analysis are the calibration and quantitative measurement of a complex matrix. This study proposes the use of borate fusion as an alternative sample preparation procedure for the quantitative measurement of Al, Fe, Si and Ti in bauxite by LIBS. Analytical calibration curves were made using bauxite certified reference materials (CRM), and the precision and accuracy of the methods were evaluated by analysing an additional bauxite CRM, using two different approaches: pressed powder pellets and fused glass beads. The borate fusion method was the most suitable sample preparation technique, since particle size effects and matrix interference could be minimised, obtaining better linearity on the analytical calibration curves (r2), and more accurate and more precise results for bauxite analysis. 相似文献
15.
16.
贵州猫场铝土矿成矿环境分析 总被引：1，自引：1，他引：0
黔中隆起后的碳酸盐岩及粘土岩类在长期物理、化学作用下,首先形成红粘土;红粘土进一步风化,而后分解成Al、Fe的氧化物、氢氧化物,在溶坑和溶蚀凹地内初步富集成零星分散的致密状和土状喀斯特型铝土矿,因地形改变再度进入分解破碎,为猫场最终铝土矿的形成提供物质来源—铝土矿碎屑。这些铝土矿碎屑和Al、Fe的氧化物、氢氧化物被地表和地下水以不同形式搬运到猫场十溶蚀湖中,按碎屑、化学、生物沉积规律形成猫场古溶蚀湖沉积铝土矿床。 相似文献
17.
18.
改性铝土矿做净水剂，与市售其它混凝剂比较，具有ＰＨ值适用范围宽，对水中阴阳离子，尤其是对ＳＯ＾２－４的吸附能力强等优点。去除水中的浊度，颜色，ＣＯＤ等同于市售其它混凝剂。 相似文献
19.
Colloidal-sized material from the Patuxent River estuary, Maryland, was analyzed for more than 30 elements by instrumental neutron activation analysis. Sample data from stations ranging in salinity from 0.04 g/kg to 12 g/kg indicate that the winter colloidal material is dominated upstream by poorly crystallized clay minerals and iron oxide, but above a salinity of 10 g/kg, it consists primarily of carbonaceous material. Winter colloidal material decreases non-conservatively seaward from 29 to 0.6 mg/l. The summer colloidal material, however, is carbon-rich throughout the estuary and the amount of colloidal material in the upper water column does not change appreciably with increasing salinity. Many trace elements (Cs, Hf, Rb, Se, Th, V and the REE) covary with Al and probably are associated with the clay component. Other elements (As, Ba, Sb, Se, U and Zn) are considerably enriched relative to Al and may covary with the organic component. The results suggest that the freshwater winter colloidal system is a product of continental weathering processes, whereas the summer colloidal material is derived primarily from estuarine biological processes. 相似文献
20.
广西靖西县新圩铝土矿Ⅶ号矿体矿石热分析 总被引：1，自引：0，他引：1
广西靖西新圩堆积型铝土矿为我国典型的一水铝型铝土矿。以新圩堆积型铝土矿的典型样品为研究对象,通过X衍射分析确定其矿物组成,进一步借助差热(DTA)与热重(TG/DTG)分析,探索铝土矿石加热过程。X衍射分析显示5个铝土矿样品矿物组成主要为硬水铝石、赤铁矿、绿泥石、三水铝石、锐钛矿、金红石、针铁矿以及少量的高岭石。差热(DTA)分析显示铝土矿样品有2个明显的吸热峰,分别为三水铝石和硬水铝石吸热峰;热重(TG/DTG)曲线显示样品分解分为4个阶段,分别为吸附水失去阶段和三水铝石、针铁矿、硬水铝石脱羟基作用阶段。利用热重(TG/DTG)数据分别计算了硬水铝石、三水铝石、针铁矿矿物相对百分含量,与国内外同类型铝土矿矿石热分析特征对比显示具有大体一致的热分析特征。 相似文献