共查询到20条相似文献，搜索用时 31 毫秒
1.
The cavitation and cavitation-ablation mechanisms of formation of mineral nano-and microspherules in hydrothermal fluids are considered. The formation conditions of nano-and microspherules were studied with regard to the depth of host rock occurrence on the basis of the theory describing the cavitation mechanism. It is shown that the temperature and pressure of hydrothermal fluid as functions of the depth of host rock occurrence may markedly affect the dimensions of cavitation bubbles, the temperature within them at the moment of greatest compression, and the time of bubble collapse in the fluid. the dimensions of nano-and microspherules produced by cavitation depend only slightly on the depth of host rock occurrence and are mainly controlled by the thermophysical properties of their constituents. Characteristic dimensions of nanospherules formed as a result of ablation from the surface of overheated material have been obtained. 相似文献
2.
E. M. Galimov G. A. Karpov V. S. Sevast’yanov S. N. Shilobreeva A. P. Maksimov 《Geochemistry International》2016,54(10):829-833
The origin of diamonds in the lava and ash of the recent Tolbachik eruption of 2012–2013 (Kamchatka) is enigmatic. The mineralogy of the host rocks provides no evidence for the existence of the high pressure that is necessary for diamond formation. The analysis of carbon isotope systematics showed a similarity between the diamonds and dispersed carbon from the Tolbachik lava, which could serve as a primary material for diamond synthesis. There are grounds to believe that the formation of Tolbachik diamonds was related to fluid dynamics. Based on the obtained results, it was suggested that Tolbachik microdiamonds were formed as a result of cavitation during the rapid movement of volcanic fluid. The possibility of cavitation-induced diamond formation was previously theoretically substantiated by us and confirmed experimentally. During cavitation, ultrahigh pressure is generated locally (in collapsing bubbles), while the external pressure is not critical for diamond synthesis. The conditions of the occurrence of cavitation are rather common in geologic processes. Therefore, microdiamonds of such an origin may be much more abundant in nature than was supposed previously. 相似文献
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2008年10月和2009年10月在祁连山老虎沟12号冰川积累区采集了2个雪坑样品, 通过样品中δ18O、可溶性离子、不溶性微粒的变化特点划分了雪坑季节. 2008年雪坑季节变化信号明显, 而2009年雪坑不明显, 微粒浓度、Ca2+与Mg2+含量在春季较高. 离子平衡、pH值、电导率及同期气象记录观测资料均显示, 2009年雪坑受淋溶影响较大. 淋溶强烈时, 受融水造成的粉尘溶解及离子淋溶的影响, 雪坑中微粒与Ca2+、Mg2+变化趋势不甚一致; 与Ca2+相比, Mg2+变化能够较好表征微粒的变化; d>5 μm的微粒可能更易于溶解迁移. 通过分析室内雪冰样品在液态下的变化, 发现伴随静置过程微粒的质量浓度呈下降的趋势, 期间Ca2+、Mg2+却呈现增加的变化, 可能与碳酸盐矿物的溶解有关. 相似文献
5.
《International Journal of Mineral Processing》2005,77(1):1-45
The properties of thin liquid films (TLF) are of paramount significance for colloidal disperse systems, and a number of industrial processes, including froth flotation. In flotation, the bubble–particle attachment is controlled by the thinning and rupture of the intervening liquid film between an air bubble and a mineral particle. The froth evolution and its transient stability are also a function of the drainage and rupture of liquid films between air bubbles. Surface-active substances (surfactants) are used as flotation reagents to control the behavior of the liquid films. This paper presents a review of our research in the area of surfactant adsorption, surface forces and liquid films. It mainly focuses on the validation, application and extension of the Stefan–Reynolds theory on the liquid drainage. The extension of the Stefan–Reynolds theory comprises surface forces (disjoining pressure), surface tension variation, caused by the adsorption and diffusion of surfactants. Both the experimental and theoretical results are mostly related to the free (foam) films formed between two bubbles but can be principally extended to emulsion films between two oil drops and wetting films between an air bubble and a solid surface. 相似文献
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Pan Yaoxiang 《岩土力学》1985,6(1):59-66
Since two membranes and a hydraulic cavity are introduced, the pressure cell with secondary membrane has a transitive loss. The paper analyses transitive loss theoretically and gives a unified formula in the following cases: (1) Under uncompressible liquid; (2) Under compressible liquid; (3) With air bubbles in force transfer cavities. A few calculations for circular membranes are made. The relation between allowable air bubble ratio and allowable transitive loss is also given in this paper. Both theoretical and experimental results prove that the high air bubble ratio is one of the bad linearity at low pressure. 相似文献
8.
由于二次膜压力盒具有两个承压膜和充有传力液的腔室,因而二次膜压力盒存在着传力损耗。本文从理论上对压力盒的传力损耗进行了分析,并对以下三种情况进行了讨论: (1) 传力液不可压缩(2) 传力液可压缩; (3) 传力腔内含有气泡。文中列出了传力损耗ε的统一计算公式,并按圆形膜片做了计算。最后给出了容许气泡率A_L与容许传力损耗ε_L之间的关系。理论和实验研究结果都证明含气率高是压力盒低压端线性度不好的原因之一。 相似文献
9.
A. Yu. Ozerov 《Petrology》2009,17(7):653-668
Processes in the feeders of basaltic volcanoes during Strombolian-type eruptions were examined with the use of a complex apparatus
for modeling basaltic eruptions (CAMBE), which was designed and manufactured by the authors for this purpose. The experimental
setup consists of modeling and registering units and has a height of 18 m. It was designed with regard for the geometric dimensions
of a natural feeding volcanic system: the ratio of the inner diameter of the feeder to its height is approximately 1: 1000.
CAMBE was the first modeling equipment making possible passing a flow of gas-saturated liquid through the conduit, which allowed
us to study the nucleation of gas bubbles, their growth, coalescence, transformations of the gas structures, and the kinetics
of the gas phase. The experiments were carried out in a manner that made it possible to eliminate effects of structural barriers
and fluctuations in the liquid flow velocity. As a result of the experiments, a new (previously unknown) regime in the flow
of two-phase systems through a vertical conduit was discovered: the cluster regime, which is characterized by systematically
alternating dense accumulations of gas bubbles (bubble clusters) and liquid devoid of a free gas phase. It is demonstrated
that the liquid, bubbly, cluster, and slug regimes systematically grade into one another and are polymorphic modifications
of gas-saturated liquids moving through vertical conduits. Our data led us to propose a new model for the gas-hydrodynamic
movement of magmatic melt through the conduit of a basaltic volcano: depending on the gas-hydrodynamic regime in the volcanic
vent, various types of eruptive activity (up to explosions) may take place. The analyses of basaltic magma explosions allowed
us to describe them from a new standpoint and recognize the following four major modes of their manifestations at the surface:
(1) weak ash explosions early during the cluster regime, (2) strong ash explosions during the mature cluster regime, (3) bomb
explosions during the slug regime, (4) bomb grading to ash explosions during the slug regime associated with trains of small
bubbles. 相似文献
10.
Simon M. Iveson 《国际地质力学数值与分析法杂志》2003,27(7):627-632
Pietruszczak and coworkers (Internat. J. Numer. Anal. Methods Geomech. 1994; 18 (2):93–105; Comput. Geotech. 1991; 12 ( ):55–71) have presented a continuum‐based model for predicting the dynamic mechanical response of partially saturated granular media with viscous interstitial liquids. In their model they assume that the gas phase is distributed uniformly throughout the medium as discrete spherical air bubbles occupying the voids between the particles. However, their derivation of the air pressure inside these gas bubbles is inconsistent with their stated assumptions. In addition the resultant dependence of gas pressure on liquid saturation lies outside of the plausible range of possible values for discrete air bubbles. This results in an over‐prediction of the average bulk modulus of the void phase. Corrected equations are presented. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
11.
The mineral field structure of a complex placer is a set of features reflecting the distribution and correlation of useful
and accompanying placer-forming minerals, their variation trends, the ordering degree of mineral assemblages, inhomogeneity
levels, etc. The mineral field structure is one of the most important characteristics of polymineral placers. Along with other
properties, it allows one to judge the regional and local formation condition of a placer and to assign it to a certain dynamic
class. The informativeness of this parameter increases if the mineral field inhomogeneity of complex placers is estimated
using various statistical models, in particular, the method of major components, which is one of the modifications of the
factor analysis. This method allows one to restore the structure of such a multifactor system as mineral assemblages of complex
heavy-mineral placers. This analysis yields particularly interesting results in the reconstruction of formation environments
of fossil placers that have lost connection with the recent topography (Devonian gold-diamond-rare metal placers in the middle
Timan region and Mesozoic-Cenozoic titanium-zirconium placers in northern Kazakhstan). It is demonstrated that the mineral
field of a proximal polymineral placer is extremely disordered; its mineral assemblages primarily reflect the provenance rock
composition and only insignificantly the formation environment of the placer itself. The mineral field of a complex coastal-marine
placer of heavy minerals (CMP), in contrast, reflects practically exclusively the lithodynamic situation within the shoreline
zone, including an influence of local factors. Only in exceptional cases, the inhomogeneity of the mineral field of a certain
CMP reflects an additional influence of rocks of the source area. 相似文献
12.
Anca Avram Daniela Constantin Daniel Veres Szabolcs Kelemen Igor Obreht Ulrich Hambach Slobodan B. Marković Alida Timar-Gabor 《Boreas: An International Journal of Quaternary Research》2020,49(3):615-633
The loess–palaeosol sequence of Batajnica (Vojvodina region, Serbia) is considered as one of the most complete and thickest terrestrial palaeoclimate archives for the Middle and Late Pleistocene. In order to achieve a numerical chronology for this profile, four sets of ages were obtained on 18 individual samples. Equivalent doses were determined using the SAR protocol on fine (4–11 μm) and coarse (63–90 μm) quartz fractions, as well as on polymineral fine grains by using two elevated temperature infrared stimulation methods, pIRIR290 and pIRIR225. We show that the upper age limit of coarse quartz OSL and polymineral pIRIR290 and pIRIR225 techniques is restricted to the Last Glacial/Interglacial cycle due to the field saturation of the natural signals. Luminescence ages on coarse quartz, pIRIR225 and pIRIR290 polymineral fine grains are in general agreement. Fine quartz ages are systematically lower than the coarse quartz and pIRIR ages, the degree of underestimation increasing with age. Comparison between natural and laboratory dose response curves indicate the age range over which each protocol provides reliable ages. For fine and coarse quartz, the natural and laboratory dose response curves overlap up to ~150 and ~250 Gy, respectively, suggesting that the SAR protocol provides reliable ages up to c. 50 ka on fine quartz and c. 100 ka on coarse quartz. Using the pIRIR225 and pIRIR290 protocols, equivalent doses up to ~400 Gy can be determined, beyond which in the case of the former the natural dose response curve slightly overestimates the laboratory dose response curve. Our results suggest that the choice of the mineral and luminescence technique to be used for dating loess sediments should take into consideration the reported limited reliability. 相似文献
13.
W.J. Phillips 《Lithos》1973,6(3):235-244
Attention is drawn to the nomenclature of spheroidal structures, and the textures are interpreted in terms of central, marginal or disseminated crystal nucleation. The essential physical characteristics of the nucleation and growth of crystals, bubbles of a low density gaseous phase, and globules of liquid with a density comparable with that of the magma are described. It seems likely that crystallization within an immiscible liquid fraction would proceed from disseminated nuclei thus producing a rock texture, rather than a cavity filling texture developed from marginal nucleation which is a characteristics of crystallization within gas cavities. Structures of mineralogical features which clearly indicate early liquid immiscibility or subsequent retrograde boiling are rarely preserved because of the nature of the processes, but it is suggested that both processes play a greater part in the formation of certain igneous rocks than in generally realized. 相似文献
14.
The behaviour of quasi-saturated materials is important to consider when designing cuttings and embankments in which earthwork materials are compacted to the optimum proctor density. Under this condition, the in-pore gaseous phase takes the form of air pockets and bubbles embedded within the liquid phase, which significantly affects the overall behaviour of the soil. The assessment of highly saturated soils thus requires a precise understanding of hydro-chemo-mechanical couplings between the entrapped air, the in-pore liquid and the solid skeleton. This paper presents a fully coupled poromechanical model that separates the kinematics and the mechanical behaviours of the phases in their interactions with each other (e.g., liquid water, dissolved air, gaseous air and solid matrix). The assumptions about the entrapped air behaviour are defined from a bibliographic study, and linear elastic behaviour is used for both the liquid phase and the solid skeleton. The model is implemented in the FEM code COMSOL and is subsequently used to simulate oedometric tests under different loading paths: undrained compression or imposed liquid pressure variation at constant stress. The behaviour, which shows a continuous transition from unsaturated to saturated, is logical and consistent with available experimental data. 相似文献
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利用原型监测成果分析和介绍了葛洲坝一号船闸反孤形输水阀门空化特性.通过对噪声信号分析,阐述了几种运行方式下阀门底缘空化及顶缝空化特性,首次揭示阀门开启之初底缘和底板之间也可能出现缝隙空化.介绍了空化对门后水流压力和对阀门启门力脉动的影响,分析了空化低频噪声和阀门振动的相互关系. 相似文献
17.
I. V. Belyatinskaya V. I. Feldman V. V. Milyavsky T. I. Borodina G. E. Valyano A. A. Belyakov 《Moscow University Geology Bulletin》2010,65(5):289-300
In this work the patterns of shock-metamorphic transformations of rock-forming minerals (amphibole, plagioclase, and clinopyroxene)
in layered crystalline schists (Southern Ural) appeared as a result of planar shockwave loading of rocks. Comparison of the
data obtained with those of diaplect transformations of the above-listed minerals in the field and as a result of experiments
with convergent spherical shockwaves for this rock revealed essential differences between transformations. The formation of
polymineral shock-thermal apoamphibole and apoclinopyroxene aggregates that were typical for the conditions of spherical shockwave
compression was not observed during stage shockwave compression, even at 52 GPa. 相似文献
18.
《Quaternary Science Reviews》2003,22(10-13):1131-1138
In this investigation we evaluate several proposed optically stimulated luminescence single-aliquot regeneration (OSL SAR) procedures to determine which technique has the greatest potential to yield accurate ages for samples collected from tuff-derived alluvial sediments within the narrow, sharply incised canyon systems of the Pajarito Plateau of northern New Mexico. The SAR data collection methods evaluated are: infrared-stimulated luminescence (IRSL), post-IR blue-OSL, IRSL with TL annealing cycles on polymineral fine-grains, and blue-OSL on quartz fine sand. A single-grain laser luminescence (SGLL) procedure for quartz sand is also evaluated. Age estimates obtained from these methods are compared with radiocarbon, soil PDI (profile development index), and IRSL multi-aliquot additive dose (MAAD) age constraints. Our results indicate that the modal De of quartz sand SGLL dose distributions yield ages that are consistent with radiocarbon and PDI age constraints for the tuff derived sediments in this investigation and appears to be the most promising method for studies in this area. Additionally, two fine-grained polymineral methods, IRSL SAR and traditional IRSL MAAD, produced ages that were generally in agreement with the SGLL ages and with available 14C and PDI age constraints. At the present stage of research, we advocate using quartz sand SGLL in conjunction with IRSL SAR or even IRSL MAAD for polymineral fine-grains to provide the most robust and reliable luminescence age data sets for tuff-derived sediments. 相似文献
19.
现代冰川雪冰中的微粒是重建过去气候环境变化的一项重要替代性指标。根据前人对极地冰盖和山地冰川冰芯及雪坑样品中的微粒粒径、矿物特征和含量变化等研究成果,讨论了微粒粒径变化,微粒与火山活动、大气气溶胶的关系,以及冰芯测年、微粒来源等相关分析,认为微粒中的代表性矿物、火山玻璃、粗糙系数和粒径分布可作为确定微粒源区的指标;微粒含量的变化与大气环流、气温高低及干湿程度密切相关,微粒含量的高值对应冷干气候,反之为暖湿;大气环流加强时,微粒含量增加,反之减少。微粒研究还能获得如火山活动、人类影响等特殊事件的信息。 相似文献
20.
Conventional and non-conventional flotation for mineral processing and for water (and wastewaters) treatment and reuse (or recycling) is rapidly broadening their applications in the mining field. Conventional flotation assisted with microbubbles (30–100 μm) finds application in the recovery of fine mineral particles (< 13 μm) and flotation with these fine bubbles is being used as a solid/liquid separation to remove pollutants. The injection of small bubbles to conventional coarse bubbles flotation cells usually leads to general improvements of the separation parameters, especially for the ultrafines (< 5 μm) ore particles. Results obtained are believed to occur by enhancing the capture of particles by bubbles, one of the main drawbacks in fine ore flotation. It is believed that by decreasing the bubble size distribution (through the injection of small bubbles), increases the bubble surface flux and the fines capture. DAF or dissolved air flotation with microbubbles, treating water, wastewater and domestic sewage is known for a number of years and is now gradually entering in the mining environmental area. This technology offers, in most cases, advantages over settling, filtration, precipitation, or adsorption onto natural and synthetic adsorbents. The targets are the removal of oils (emulsified or not), ions (heavy metals and anions) and the reuse or recirculation of the process waters. Advantages include better treated water quality, rapid start up, high rate operation, and a thicker sludge. New applications are found in the mining vehicles washing water treatment and reuse, AMD (acid mining drainage) neutralization and high rate solids/water separation by flotation with microbubbles. This work reviews some recent applications of the use of microbubbles to assist the recovery of very small mineral particles and for the removal of pollutants from mining wastewaters. Emphasis is given to the design features of innovative devices showing the potential of conventional and unconventional DAF flotation. 相似文献