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1.
A technique has been devised for major element whole rock analysis using the electron microprobe. Rock powders are fused on a strip heater using a low voltage, high amperage source and quenched to form a glass bead in a container pressurized with argon. Sample weights of 20 mg to ~ 300 μg with run times of 20–60 sec produce sufficient material for analysis. Analyses of the fused samples compare favorably with those achieved by X-ray fluorescence and neutron activation for major elements in a wide range of silicate rock compositions. Analytical errors for major element concentrations are generally 5% or less. Alkali losses for Rb are ~10% at the 20 ppm level as determined by isotope dilution mass spectrometry. Sodium determinations compare favorably with those obtained by neutron activation analysis.  相似文献   

2.
A rapid X-ray fluorescence technique has been developed to determine the BPL (Ca3(PO4)2 or Bone Phosphate of Lime) content of various streams in Florida phosphate beneficiation and in supporting laboratory flotation experiments. The method, which requires simple sample preparation, a 100-sec counting, and has an accuracy of better than 2% BPL (0.4% P), employs an Fe55 radioactive source and a room temperature detector to analyze for calcium. The BPL values, which can not be obtained readily and directly because of the weak fluorescence of phosphorus, are instead derived from a close correlation found to exist between the phosphorus and calcium concentrations.  相似文献   

3.
A new microscope vacuum heating stage and gas analyzer has been developed for measurement of H2O, CO2, SO2, and noncondensable gas (H2, CO, N2, Ar, CH4, etc.) evolved from samples, particularly natural glass, at temperatures up to 1280°C. The gas evolved upon heating to 1280δC is collected in a liquid nitrogen cold trap. Gas components are identified by the characteristic vapor pressure and temperature ranges over which solid and vapor are in equilibrium during sublimation of individual components. The masses of CO2, SO2, and H2O derived from samples and blanks are calculated using the ideal gas law, the molecular weights of the components, and the gauge constant (i.e. the ratio of the number of moles of a gas to its partial pressure in the constant volume). Results obtained by repeated determinations of H2O, CO2, and SO2 evolved from a submarine basaltic glass from Kilauea volcano, Hawaii, (average sample mass = 3 × 10?3 g) gave probable errors for the determinations of H2O (0.23%), CO2 (0.025%), and S (0.071%) equal to 4, 10, and 8% respectively, of the concentrations. Determinations of H2O in smaller samples of H2O-poor basaltic pumice show a linear proportionality (0.063%) between the measured H2O and the sample mass over the range 0.1 × 10?6 to 1.7 × 10?6 g H2O. Comparisons of H2O determinations by this technique with those obtained by Penfield, gas chromatic, microcoulometric, and vacuum fusion techniques used elsewhere show reasonably good agreement. Determinations of SO2 by this technique agree reasonably well X-ray fluorescence and electron microprobe determinations of sulfur. Determinations of CO2 by the present technique are reproducible but cannot be compared directly to measurements made in other labs because of differences in samples analyzed. The principle advantages of this analytical technique are the very small sample required, the simultaneous determination of H2O, CO2, SO2 and noncondensable gas, the avoidance of calibration procedures dependent on chemical standards, and the visual observations that can be made during sample outgassing.  相似文献   

4.
核技术在东坪金矿勘查中的应用与研究   总被引：2，自引：0，他引：2  
葛良全  门春茂 《铀矿地质》1995,11(6):357-361
核技术用于金矿勘查的方法主要有Ｘ射线荧光法、γ能谱法、氡（射气）法、中子活化分析法等。本文论述了核技术勘查金矿的地质、地球化学依据、物理基础和方法技术。实践表明：以γ能谱方法（Ｋ，Ｋ／Ｔｈ为参数）可圈定与金矿化有关的钾化蚀变带；以Ｘ射线荧光法可确定含金矿脉的位置，原位划分金矿体边界；中子活化分析法（ＲＥＥ）可揭示深部盲矿体。  相似文献   

5.
A new X-ray diffraction method has been developed whereby the weight percentages of aragonite and low and high-magnesium calcite are determined from the integrated peak areas of samples. Peak areas are measured by a step scanning method. The weight percentages of MgCO3 in calcite are determined from the angular position of the calcite peak. This technique uses a direct calculation method which simplifies the preparation of the samples and the calibration processes and increases the quality of the results. The fully automatic method uses a desk-top computer to guide the diffractometer and to carry out the necessary calculations. Tests on precision and accuracy of the method indicate that results with less than ± 4% error (mineral %) and ± 0.6% error (MgCO3%) are obtainable for all samples even those with a low (10%) carbonate content.  相似文献   

6.
New isotope dilution results are presented for Rb and Sr concentrations in U.S.G.S. standard rocks and NBS-70a K-feldspar. The results (based on at least five analyses of each rock), are generally accurate to ± 0.5% and resolve discrepancies in previously published data. X-ray fluorescence analyses of the same samples yield Rb and Sr determinations which are only accurate to ± 5%, but Rb/Sr ratios which are as precise and in excellent agreement with the isotope dilution values. It is concluded that X.R.F. determination of Rb/Sr ratios is perfectly suitable for whole-rock Rb1bSr geochronology.87Sr86Sr ratios have been determined on G-2, GSP-1, BCR-1 and AGV-1 as well as the Eimer and Amend SrCO3 standard.  相似文献   

7.
This review for the year 2003 deals with three relatively well-established, mature, analytical techniques (neutron activation analysis, atomic absorption spectrometry and X-ray fluorescence spectrometry) that nevertheless remain very important for the characterisation of geological and environmental samples. Developments in neutron activation analysis included modification to the technique in relation to the determination of platinum-group elements, as well as consideration of sample size in ore grade estimation. A considerable body of literature was published on the application of atomic absorption spectrometry in the analysis of environmental samples. Many of these proposed technical and methodological improvements, notably in extraction procedures. X-ray fluorescence spectrometry saw developments in in situ analysis, synchrotron micro-XRF (μ-SRXRF) and a confocal X-ray set-up for 3D elemental imaging. XRF technologies were used in the analysis of geological samples, reference materials, glasses, solutes and environmental materials.  相似文献   

8.
Heterogeneity effects often limit the accuracy of synchrotron X-ray fluorescence microprobe elemental analysis data to ± 30%. The difference in matrix mass absorption at Kα and Kβ fluorescence energies of a particular element can be exploited to yield information on the average depth-position of the element or account for heterogeneity effects. Using this technique, the heterogeneous distribution of Cu in a simple layered sample could be resolved to a 2 × 2 × 10 (x, y, z, where z is the depth coordinate) micrometer scale; a depth-resolution limit was determined for the first transition metal series and several other elements in calcite and iron oxide matrices. For complex heterogeneous systems, determination of average element depth may be computationally limited but the influence of heterogeneity on fluorescence data may still be assessed. We used this method to compare solid-state diffusion with sample heterogeneity across the Ni-serpentine/calcite boundary of a rock from Panoche Creek, California. We previously reported that Ni fluorescence data may indicate solid state diffusion; in fact, sample heterogeneity in the depth dimension can also explain the Ni fluorescence data. Depth heterogeneity in samples can lead to misinterpretation of synchrotron X-ray microprobe results unless care is taken to account for the influence of heterogeneity on fluorescence data.  相似文献   

9.
Twelve samples of Nigerian laterites were obtained from Ilorin, a rapidly growing urban center, and capital of Kwara State, Nigeria. Three varieties of laterites (clay, gravel and crust) were identified and subjected to mineralogical, chemical and geotechnical analyses which included: identification of clay and non-clay minerals by X-ray diffraction (XRD) techniques; chemical composition by X-ray fluorescence spectrometer analysis; pH of soil in water; moisture contents and specific gravity determinations, grain size analysis; compaction test by Harvard Compaction Apparatus and unconfined compressive strength determination.The laterite soil samples are composed of kaolinite and illite clay minerals with some quartz and feldspar. They were found to be rich in SiO2 (45%) Fe2O3, (16%) and Al203 (10%).These soils yielded maximum strength when compacted on the dry side of their optimum moisture content (OMC).The soils are not expected to perform very well as concrete aggregates since they contain high amounts of SiO2 and Fe2O3. These oxides are known to have deleterious effects on construction materials, particularly concrete aggregates.  相似文献   

10.
Abundances of O, Si, Al and Mn have been determined in Luna 20 fines sample 22001,9 by instrumental neutron activation analysis. The abundances of O, Si and Al are among the highest we have observed in lunar samples and reflect a highlands origin for much of this regolith sample. The Luna 20 abundances reported here most closely resemble those we have determined in four samples of two Apollo 16 fines, rock 14310, and a clast from breccia 15459. The Luna 20 OSi ratio of 1.96 ± 0.05 is similar to that in most other lunar samples, but the AlSi ratio of 0.532 ± 0.024 is exceeded only by our data on the Apollo 16 fines. This AlSi ratio is in agreement with the value of 0.55 ± 0.06 determined by the remote X-ray fluorescence experiment for the highlands between Mare Crisium and Mare Smythii which lie near the Luna 20 site (Adleret al., 1972).  相似文献   

11.
粉末压片制样-X射线荧光光谱法测定铁矿石中锌砷锰   总被引：1，自引：1，他引：0  
尹静  黄睿涛 《岩矿测试》2011,30(4):491-493
应用X射线荧光光谱仪测定铁矿石中的锌、砷、锰含量,采用粉末压片法制样,并研究了制样的条件,确定了仪器最佳参数,建立了标准曲线。经国家实物标准铁矿石样品验证,测定值与标准值吻合,三元素的偏差均小于±0.007%;精密度试验表明相对标准偏差(n=10)均小于2.80%。大量实验数据表明,压片制样-X射线荧光光谱法测定锌、砷、锰元素的精密度高,准确可靠。该方法在检测准确度和分析速度上可以满足钢厂生产要求。  相似文献   

12.
We consider the evolution of close binaries resulting in the most intensive explosive phenomena in the stellar Universe—Type Ia supernovae and gamma-ray bursts. For Type Ia supernovae, which represent thermonuclear explosions of carbon-oxygen dwarfs whose masses reach the Chandrasekhar limit during the accretion of matter from the donor star, we derive the conditions for the accumulation of the limiting mass by the degenerate dwarf in the close binary. Accretion onto the degenerate dwarf can be accompanied by supersoft X-ray radiation with luminosity 1–104 L ⊙. Gamma-ray bursts are believe to accompany the formation and rapid evolution of compact accretion-decretion disks during the formation of relativistic objects—black holes and neutron stars. The rapid (～1 M ⊙/s) accretion of matter from these disks onto the central compact relativistic star results in an energy release of ～0.1 M ⊙ c 2 ～ 1053 erg in the form of gamma-rays and neutrinos over a time of 0.1–1000 s. Such disks can form via the collapse of the rapidly rotating cores of Type Ib, Ic supernovae, which are components in extremely close binaries, or alternately due to the collapse of accreting oxygen-neon degenerate dwarfs with the Chandrasekhar mass into neutron stars, or the merging of neutron stars with neutron stars or black holes in close binaries. We present numerical models of the evolution of some close binaries that result in Type Ia supernovae, and also estimate the rates of these supernovae (～0.003/year) and of gamma-ray bursts (～10?4/year) in our Galaxy for various evolutionary scenarios. The collimation of the gamma-ray burst radiation within an opening angle of several degrees “matches” the latter estimate with the observed rate of these events, ～10?7–10?8/year calculated for a galaxy with the mass of our Galaxy.  相似文献   

13.
Sixteen alluvial and terrace soils from Japan and Thailand were separated into six fractions ; an amorphous sesquioxide and combined organic matter fraction, crystalline sesquioxides, clay, silt, fine sand and coarse sand. Content of ten major and minor elements in these six fractions was analyzed; SiO2, A12O3, Fe2O3, MgO, CaO, K2O, TiO2, Rb2O and SrO were determined by X-ray fluorescence spectrometry, and Na2O was determined by neutron activation analysis. The clay, silt, fine sand and coarse sand mineralogy were estimated semi-quantitatively by X-ray diffraction methods.We propose three indices of geochemical maturity for the soils and test their usefulness as measures of the degree of weathering. Three concomitant factors are proposed to measure the relative resistate, hydrolyzate and oxidate nature of the major elements in the soils.  相似文献   

14.
A field-lab technique has been developed to aid in the geochemical exploration for feldspars involving the determination of the K/Na ratio of feldspar samples with recently improved ion-selective electrodes. Feldspar is dissolved in a mixture of m-benzene disulfonic acid and hydrofluoric acid. The solution is neutralized with tetramethylammonium hydroxide in the presence of CDTA. K and Na determinations are then made with ion-selective electrodes in the neutral solution. The precision and accuracy of the technique have been tested and closely approach that of the flame photometer.  相似文献   

15.
The fluorescent pellet method of uranium determination is a recognized, precise, and accurate technique. What may be termed routine procedures are slow, and consequently expensive, for large-scale geochemical surveys. Attempts to develop a more rapid analytical technique result in a lack of precision which is directly proportional to the magnitude of pellet variability and fluorescence quench effects. Experimental data confirm the argument that these variables constitute matrix effects because they affect the optical, or more specifically the absorptive, characteristics of U-bearing pellets. A method is described whereby this optical variation is quantified using IR radiation to measure what may conveniently be called absorption (A). The relationship of A to the fluorescence, F, is illustrated for blank pellets, laboratory standards, and lake-sediment standards. From these data a correction procedure that accounts for variations in pellet weight, and hence thickness, pellet crystallinity and quench effects, is developed. In terms of the most important quenching agent, Fe, the optimum range for such a correction is 0.5–10.0%. Using this technique, one hundred plus samples can be analyzed per working day with a precision and an accuracy of the order of ±5%.  相似文献   

16.
We used neutron activation analysis to determine ten trace elements retained in Abee (E4) samples heated at 400–1000°C for 1 week in a low-pressure (initially ~ 10?5atm H2) environment. Eight elements generally are lost progressively with increasing temperature although gas(es) evolved from the samples apparently affect retention of some elements. In the extreme, ‘open-system’ losses are: Se—23%, Cs—40%; Te—87%; Ag, Bi, In, Tl, Zn— ≥93%. Under these conditions Co is not lost; Ga is lost only at 1000°C. At 900°C elements are lost from Abee chips in the same relative order as from Abee powder but the loss is somewhat less facile. Three of the most mobile elements—Bi, In, Tl—are lost more readily from Abee than from Allende (C3), the only other primitive chondrite studied to date. Assuming that elemental loss is a kinetic process involving mobilization from spherical grains, Bi, In, Se, Tl and Zn have different activation energies at high and low temperatures either because each element was originally present in two different sites or each has more than one loss mechanism (diffusion or desorption) in different temperature ranges.Comparison of elemental abundance patterns, patterns of statistically-significant correlations, factor analysis results and two-element correlation diagrams indicate strong similarities between heated Abee and ‘as-received’ enstatite chondrites for mobile elements. These results are consistent with a two-stage evolutionary model for enstatite chondrites involving condensation of cosmochemically fractionated primitive nebular material and subsequent loss of mobile elements from parent material by metamorphism.  相似文献   

17.
X射线荧光光谱法(XRF)是测定土壤和沉积物中锰的重要方法,具有制样简单、非破坏性测定、检测速度快等优点。目前用于建立工作曲线的土壤和沉积物标准物质的锰含量最高为2490mg/kg,采用XRF法测定受污染土壤和沉积物中的锰含量时易超出工作曲线测定范围。本文将锰标准溶液定量加入到土壤标准物质中,制备锰含量更高的校准样品,工作曲线的测定上限范围由2490mg/kg提高至3780mg/kg。该方法测定不同含量标准物质中锰含量的结果均在认定值范围内,实际样品的加标回收率为97.8%～108.3%,高含量锰的实际样品测定值与电感耦合等离子体发射光谱法测定值的相对偏差小于5.7%,相对标准偏差(RSD)小于0.4%(n=7)。实验结果表明该法测定锰含量高的土壤和沉积物的准确度和精密度良好。  相似文献   

18.
Prompt gamma neutron activation analysis was applied to the determination of the titanium, potassium, samarium and gadolinium contents of nine Geological Survey of Japan (GSJ) reference materials (JB-1, 1a, 2, 3; JA-1, 2, 3; JR-1, 2). Firstly, the values in JB-1 were determined by the standard addition method: pressed powder disks of JB-1 were used for neutron irradiation and gamma-ray measurements, after known quantities of standard reagents had been added. Secondly, the contents of eight other reference materials were determined by comparison methods using JB-1 as the comparative standard. The precision of analyses were obtained by replicate determinations on these samples. The relative standard deviation was generally less than 5%. For most samples, analysed values agreed well (< 5%) with the recommended values.  相似文献   

19.
A technique is presented by which the cut size of a classifier can be estimated without size analyses of the coarse and fine products. Using the corrected solids recovery and the classifier feed size distribution, an indicated d50 size can be determined which is usually within ± 10% of the actual cut size.By computer simulation of the classification process, actual/indicated cut size ratios were determined for a variety of operating conditions. Through the application of these ratios, it has been demonstrated that the d50 of a classifier can be estimated with an accuracy comparable to that obtained through the use of classification curves. The main limitations of this technique are that accurate measurement of the solids content in the slurry streams is required and that no information is obtained concerning the sharpness of separation.  相似文献   

20.
沙乐花岗岩位于滇西思茅地块南涧县南西沙乐乡一带,主要由黑云母二长花岗岩和花岗闪长岩组成,被少量正长斑岩侵入。LA-ICP-MS锆石U-Pb测年得出黑云母二长花岗岩的形成年龄为246.4±2.6Ma,花岗闪长岩的形成年龄为245.7±3.6Ma,表明该花岗岩体的形成时代属于早三叠世。岩石Si O2含量71.44%~76.39%,Al2O3含量12.72%~16.15%,K2O/Na2O=0.1~1.30,均属高钾钙碱性过铝-强过铝花岗岩。根据地球化学特征和微量元素构造判别图解,样品点主要落入"火山弧花岗岩"、"板内花岗岩"区域,少量落入"碰撞花岗岩"区域,表明其形成于俯冲-碰撞岩浆弧转换环境。在Sr-Yb花岗岩分类图解中,主要属常见的低Sr高Yb花岗岩,少数样品属低Sr低Yb花岗岩,其物质来源为含砂质的变质泥质岩。结合锆石定年结果及岩体产出的区域地质背景,认为沙乐花岗岩形成于缅泰马陆块与思茅地块大陆碰撞造山过程的初始阶段,同时表明昌宁-孟连洋碰撞最早时限为早三叠世。  相似文献   

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