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1.
Instrumental neutron activation in geoanalysis 总被引：1，自引：0，他引：1
Theoretical aspects of instrumental neutron activation analysis (INAA) are discussed. Various applications of INAA to exploration geochemistry are described demonstrating its capabilities and its limitations.Cost, turnaround time, high sensitivity for certain elements, the non-destructive nature of analysis and its precision and accuracy have combined to make INAA an indispensible method for multielement determination on virtually all geological matrices. Humus, vegetation, heavy minerals, lake bottom sediments as well as rocks and soils comprise the major sample types analyzed by INAA. As many as 50 elements can be determined routinely and easily by INAA. 相似文献
2.
M.I. Brittan 《International Journal of Mineral Processing》1975,2(4):321-331
Most leaching reactions involving low-grade ores are typified by highly nonlinear kinetics which reflects variability in the rate-limiting reaction mechanism whether it be chemical or transport or a combination of both. In characterizing leaching data mathematically, classical kinetic treatments are too limited while rigorous representation of all the physicochemical rate-influencing factors in real ores would be impractical.A variable activation energy model is postulated which is a compromise between these two extremes. In it the rate-limiting effects are lumped together as an Arrhenius activation energy barrier which is related to the conversion. During reaction the more reactive or accessible valuable constituent particles will tend to react first leaving behind progressively more refractory material. The model analogue of this is an increase in the activation energy and hence a decrease in the reaction rate “constant” as the conversion increases. The influence on the leaching rate of reactant concentrations is handled by classical mass-action effects.Applications describing the characterization of both base metal (copper) and precious metal (gold) leaching cases are presented. 相似文献
3.
《International Geology Review》2012,54(12):1473-1479
4.
U. Kramar 《Geochimica et cosmochimica acta》1980,44(2):379-382
This paper deals with the disturbance of INAA trace element determinations in rocks by second order activation. The degree of error in the determination of Gd by Eu in rocks is checked by experiments and compared with results of computer evaluations. The consequence of the Dy-interference for the determination of Ho was also calculated. Hints to avoid these interferences are given. 相似文献
5.
《岩土力学》2017,(11):3163-3172
华北地区深部开采矿井,高地应力作用下煤层采动诱发断层活化引起的承压水突涌是矿井水害的主要形式之一,借助相似材料模拟试验台,通过自主设计的试验装置和试验方法,以五沟煤矿F13断层为工程背景,研究承压水上煤层开采的覆岩运动破坏形态、底板裂隙发育扩展特征、断层带应力和结构演化规律,再现断层活化导水全过程。以工作面距断层带的距离为时间参照,采动诱发断层活化导水存在4个明显阶段:断层带应力超限屈服、断层带拉裂延展、两盘错动滑移、承压水导升。以承压水沿断层带的导升高度为基准,寻找承压水导升高度的相关性因素:工作面距断层带的距离与导升高度近似呈负线性关系;水压力、断层带宽度与导升高度具有正相关性,试验过程中水压力与导升高度的相关性呈现强-弱-强的变化趋势;根据试验结果和规律设计断层防水煤柱宽度为40 m,现场观察未出现明显突漏水现象、效果良好。研究成果对于揭示断层活化突水机制、指导矿井防治水具有一定的意义。 相似文献
6.
煤岩显微组分的活化能研究 总被引：4，自引：2，他引：4
热解反应中活化能（E）与生烃率的关系是煤（干酪根）结构组成的反映，这就如同指纹一样，在成熟度相同的条件下，不同的显微组分其动力特征不同。煤及显微组分化学结构的确定目前地球化学研究领域中的一个难点。利用岩石热解（Rock-Eval）、热解气相色谱（PY－GC）以及开放体系下热模拟方法，对树皮体、镜质体和丝质体不同生烃率所对应的活化能进行测定和计算，在此基础上对上述组分的化学结构进行探讨。结果显示，三种组分的生烃率－活化能关系图以及由此所反映的化学结构明显不同：树皮体热解生烃主要集中在低活化能区，其化学结构相对较为单一，主要由脂族结构组成，芳香结构及杂原子官能团相对较少；镜质体的生烃活化能稍高，其结构比树皮体要复杂些，以烷基苯和甲氧基苯为主；丝质体生烃主要集中在高活化能区，化学结构更为复杂些，除以烷基及甲氧基苯为主外，还含有一定数量的杂原子官能团以及短链脂肪烃。另外，上述三种组分的平均活化能明显不同，其中树皮体的最低，丝质体的最高，镜质体的介于两者中间。因此，生油门限也存在很大差别，在相同的热演经条件下，三者的生烃顺序依次为树皮体→镜质体→丝质体。 相似文献
7.
More recent public discourse has taken place regarding the potential correlation between seismic activity and hydraulic fracturing in shale gas reservoirs. Public fears about the risk of seismicity stem mainly from past earthquakes induced by conventional deep injections because the two types of projects share similar mechanisms of rock failure and fault activation. Although previous earthquake risks associated with fluid injection were not serious, the situation would be far more problematic if hydraulic fracturing in a shale gas reservoir triggered a similar-sized earthquake due to potential environmental issues. In fact, almost all documented injection-induced earthquakes have been associated with long-duration and high-volume injection rather than short-term (hours) pressurization (e.g., hydraulic fracturing). In general, hydraulic fracturing operations mostly induce microseismic events through rock failure and activation of small fractures. Although shale reservoirs in tectonically active zones pose a high risk of inducing large-magnitude seismic activities, the internal geological conditions and external stimulation conditions are impossible to be satisfied simultaneously to trigger activation of an entire fault and to result in a destructive earthquake during hydraulic fracturing operations. 相似文献
8.
The sorption of arsenate on modified-natural zeolites was investigated at varying chemical pretreatment. Zeolites were used
extensively for water softening, however, a few arsenic studies have been conducted with zeolites. Arsenic pollution of the
environment has received renewed attention due to toxicological evidence of its potential health hazards to humans. The ability
of modified natural zeolites (stilbite and laumontite) to remove inorganic anion was investigated. The zeolites used in this
work are stilbite-laumontite from Zeolitic Zone of the Corda Formation. Experiments were conducted to evaluate the relationships
of the arsenate in the modified natural zeolites. Laboratory experiments were conducted examining the effect of the sorption
of cationic surfactants and coagulant on stilbite-laumontite mixtures and on the subsequent sorption of arsenate by modified
zeolites. Removal of arsenate using hexadecyltrimethylammonium (HDTMA)-modified zeolites was satisfactory whereas ethylhexadecyldimethylammonium
(EHDDMA) and ALUM-modified zeolites were not removed with the same efficiency. 相似文献
9.
采用高压水热活化法对预先烧制的粉煤灰进行碱溶实验,探讨钙硅摩尔比、碱液浓度、液固比、苛性比、反应温度、反应时间等影响因素对于氧化铝溶出率的影响。考虑到氧化铝溶出率及反应成本等各方面因素,得出氧化铝溶出的适宜条件。结果表明:碱溶条件下,钙硅摩尔比为1.0,溶液碱浓度为350 g/L,液固比为10∶1,苛性比为14,反应温度280℃,活化时间为2 h。通过氧化铝溶出工艺条件的优化,可使氧化铝提取率达到95%以上。 相似文献
10.
The adsorption of copper ions on synthetic sphalerites of various iron contents was measured using a radiotracer technique. The correlation of Cu2+ ions adsorption with the pH of solution, the iron content of the solid and the degree of surface oxidation of synthetic sphalerite were determined. The experiments proved that oxidation of the surface of the sphalerite samples caused a decrease in Cu2+ ions sorption with the exception of samples of iron containing sphalerite. Acidity of the solution affected the adsorption of Cu2+ ions by deoxidized sphalerite surfaces, whereas the adsorption on oxidized surfaces did not depend on the pH. 相似文献
11.
坡缕石粘土的酸化机理及其影响因素 总被引：3，自引：1，他引：3
酸化生产活性坡缕石粘土,对于提高其品位和高效利用有重要意义。坡缕石粘土酸化机理及影响因素研究对其高效利用具有重要理论意义和实践价值。本文综述了酸化坡缕石粘土矿物组分、矿物学、比表面和孔道变化的特征以及酸化的主要影响因素等,并就坡缕石粘土酸化过程中存在的问题及研究方向做了简要论述。 相似文献
12.
通过对蛇纹石化学成分、晶体结构及键性的分析，将蛇纹石的活性基团划分为5类，即不饱和Si—O—Si键、O—Si—O键、含镁键类、羟基和氢键，并详细介绍了各类活性基团的特征，尤其对硅氧四面体悬挂键做了介绍。指出正是这些活性基团的存在使蛇纹石具有很高的化学活性和生物活性。纤蛇纹石是一维纳米纤维矿物，易进入生物细胞，并释放出OH^-、Mg^2 、SiO2及Ni^2 等，同时不饱和O—Si—O键发生断裂形成游离氧，由纤蛇纹石形成的这种碱性氧化溶液会严重影响生物机体的正常工作，并使其产生各种病变。 相似文献
13.
Yu. V. Marapulets B. M. Shevtsov I. A. Larionov M. A. Mishchenko A. O. Shcherbina A. A. Solodchuk 《Russian Journal of Pacific Geology》2012,6(6):457-464
The results of geoacoustic emission investigations carried out on the seismoactive Kamchatka Peninsula since 1999 are presented. The experiments are characterized by the application of broadband piezoceramic sound receivers (hydrophones) for recording the emission. The hydrophones were installed at the bottom of natural and artificial water reservoirs. As compared with the standard hydrophones, such receivers allow us to broaden the registration frequency range up to 0.1 Hz–11 kHz. Three-component vector receivers with the same frequency range were used simultaneously to study the spatial structure of the geoacoustic emission and the mode of the medium particle movement in a wave. In the course of the investigations, it was established that anomalies of the geoacoustic emission in the kilohertz frequency range are recorded 1–3 days before strong earthquakes at a distance of a few hundred kilometers from the epicenter. A sharp increase in the amplitude and frequency of the geoacoustic impulses, which resemble microearthquakes in pattern and last from tens of minutes to several hours, is interpreted as an anomaly. Signals at such frequencies cannot propagate from the epicenters of preparing earthquakes and represent the response of the medium at the registration point to the change of its stress-strain state. The stress field created therein determines the primary orientation of the emission sources, which can be assessed by vector-phase methods. The results of the integrated investigations of the geoacoustic emission and the Earth’s surface deformation revealed that anomalies are observed before earthquakes with a considerable increase in the strain rate during both the compression and extension of the near-surface rocks. 相似文献
14.
Eric L. Hoffman 《Journal of Geochemical Exploration》1989,32(1-3)
Various methods are described for the analysis of Au and the Pt-group elements (PGE) using different geochemical media commonly collected by the exploration geochemist. The methods described utilize primarily the Instrumental Neutron Activation Analytical technique (INAA) in use at a commercial INAA laboratory.Rocks and soils are routinely analyzed by using a Pb fire-assay preconcentration on a 20-g sample and then analyzing the resultant Ag dore bead by INAA to a detection limit of 1 ppb. Growing rapidly in popularity is the analysis of a 30-g aliquot of sample for 34 elements including Au, solely by INAA. The elements included provide a wealth of information of a geological nature.Due to the very inhomogeneous nature of Au occurring in heavy-mineral concentrates it is imperative to analyze the whole concentrate. The only method which can provide a multielement analysis and still retain the sample intact is INAA.Biogeochemistry using either humus or vegetation as the sample media is rapidly becoming widely used. INAA provides a very sensitive means of determining Au and 34 other elements rapidly and at relatively low cost.These and other methods using the INAA technique for Au and the Pt-group will be described. 相似文献
15.
The Lanta Khola is a major landslide on the North Sikkim Highway in the Indian state of Sikkim. The abnormally low width-to-length
ratio and slope instability in spite of the gentle surface slope (24°) make this slide unique. Geological, geophysical, and
geotechnical studies reveal that a major Himalayan discontinuity daylights within the slide. At the contact, the schist is
weathered to fine sand and silt with lower shear strength and permeability. The overlying gneiss is less weathered and exposed
at the contact. Surface runoff enters the contact zone through crevices in the overlying gneiss, and debris material is extruded
laterally from within this zone rendering instability, with blocks collapsing and eventually rolling down the slope after
cloud bursts. Numerical modeling of the slide confirms this mechanism of instability. Diversion of runoff, plugging of crevices,
and construction of pipe piles and horizontal drains are suggested as remedial measures. 相似文献
16.
Michele Caputo 《Tectonophysics》1983,91(1-2)
It is found that the results of the experiments made with constant strain-rate give also the creep functions. This is determined with three different assumptions on the creep modelling function, and it is seen that, to find the long-term reaction of the material, experiments with duration longer than that of these already carried out are needed. It is also found that the classic stress-strain relations representing the anelasticity of materials imply stress hardening and possibly fatigue; a method to estimate the number of cycles which could give fatigue is suggested.As an application the creep of polycrystalline halite is obtained finding also its temperature dependence and the relation between the activation energy and the temperature. 相似文献
17.
精确的定量和定年技术——中子活化技术 总被引：2，自引：0，他引：2
精确的定年技术是建立高精度层序地层时间序列的关键,而该项技术的核心是如何精确地确定地层中地层界面的年代和其他可从沉积物序列中分辨出的地质事件的年代,特别是对地层中高频沉积旋回的每个旋回上下界进行定年,并在可能的情况下恢复地层的沉积间断时间,计算地层的沉积速率和沉积周期[1,2]。我国新生代陆相湖盆由于封闭性较高,湖底沉积对气候变化的反映比较敏感,因此湖相沉积物常被当作古气候变化记录的良好载体。通过对湖泊发展史的准确恢复和对其所蕴含的古气候演变规律的深入分析,可为全球变化趋势研究提供可信的科学依据。 相似文献
18.
M. K. Horn 《Mathematical Geology》1970,2(2):131-139
A computer method has been developed that simulates gammaray spectra of geochemical thermal neutron activation experiments.
The input for the simulation includes the designation of rock type, neutron flux, sample volume and density, irradiation time,
time of detection start, duration of monitoring, and number of analyzer channels. The output of the simulation includes either
two-or threedimensional computer drawn plots of the resulting (simulated) gammaray spectra. The threedimensional plots (energy
vs counts per sec vs time of detection) allow the investigator to observe the apparent appearance and disappearance of photo
peaks, annihilation peaks, and pair production peaks of the various isotopes as a function of time. Various combinations of
irradiation, delay, and detection times result in various spectral patterns. The resultant patterns accurately simulate the
real activation experiments run under the same time conditions. The simulated spectra are useful for identifying peaks obtained
from real spectra, helping in radiochemical separation decisions, and, in general, in designing the neutron activation experiment. 相似文献
19.
对同期降水、江河水和地下水的元素组成,使用中子活化分析方法作了对比试验。降水取自分布于8个气候带的11个站,其海拔高程为5～3659m,年平均降水量为50～1571mm。河水取自各主要江河包括内陆河和海岛的12个测站以及3个实验流域,并在其附近采集地下水。降水中共检出35种元素,各站有19～31种元素,同期均有空间分布。河水中共检出39种元素,各河分别有21～31种元素。地下水中共检出35种元素,各站有30～32种元素。对其浓度组成作了由大于1000μg/L至小于0.01μg/L的分级综合。有些元素含量超出所报道的世界淡水浓度范围,小于其最低值,甚或远大于其最高值。 相似文献
20.
采动条件下断层活化易于诱发冲击地压、底板突水等动力地质灾害,如何对采场断层活化引起的一系列动力地质灾害开展超前防治预警,一直是煤矿安全开采面临的科学技术难题。从数值模拟、相似物理模拟及现场测试三个方面,概述国内外采场断层活化方面的研究现状;围绕断层活化的监测预警方法,包括微震监测技术、声发射技术、视电阻率监测技术、光纤监测技术、注水试验等,从方法原理、研究现状、技术特点等方面对现有的主要测试与评价方法进行了总结;结合当前国内断层复杂区的煤炭资源开采,重点分析断层活化诱发的几类典型动力地质灾害形成机制及其内在联系;当前,对于采动诱发下的断层活化多维多尺度全程精细化监测技术等研究工作仍然不足,基于煤矿开采精准化、智能化需求,指出断层复杂区煤层开采研究应向多场耦合、精细化模型构建、多手段综合探查、智能预警等方向发展。认为通过进一步开展断层活化的基础理论、精细化模拟、多维多场多尺度监测预警的技术系统研究,可为煤矿智能化引领下的矿井地质保障工作提供坚实基础。 相似文献