Mechanical Properties Of Minerals Research Articles

Mechanical properties of minerals in lunar and HED meteorites from nanoindentation testing: Implications for space mining

AbstractThis study analyzes the mechanical and elemental properties of lunar meteorites DHOFAR 1084, JAH 838, NWA 11444, and HED meteorite NWA 6013. Utilizing microscale rock mechanics experiments, that is, nanoindentation testing, this research reveals significant heterogeneity in both mechanical and elemental attributes across the mineral samples. Olivines, pyroxene, feldspar, and spinel demonstrate similar compositional and mechanical characteristics. Conversely, other silicate and oxide minerals display variations in their mechanical properties. Terrestrial olivines subjected to nanoindentation tests exhibit increased hardness and a higher Young's modulus than their lunar counterparts. A linear correlation is observed between the H/Er ratio and both plastic and elastic energies. Additionally, the alignment of mineral phases along a constant H/Er ratio suggests variations in local porosity. This study also highlights the need for further research focusing on porosity, phase insertions within the matrix, and structural orientations to refine our understanding of these mechanical characteristics. The findings have direct implications for in situ resource utilization strategies and future state‐of‐the‐art impact models. This comprehensive characterization serves as a foundational resource for future research efforts in space science and mining.

Application of AFM on Identifying Mechanical Properties of Individual Minerals and Surface Properties of Crack with High Resolution in Shale

Improving the resolution and accuracy of the mechanical properties of organic-rich shale is very important. The results can reveal the mechanical properties of shale from micro scale and serve as a guide for the design of hydraulic fracture optimization parameters. This study introduced an advanced technique to obtain the mechanical properties of shale with high resolution (58.6 nm/pixel) by combining SEM, EDS, and Atomic Force Microscopy (AFM). To locate the target area in SEM and AFM accurately, a positioning technique that uses special distributions of pyrite was established. AFM PeakForce QNM mode was selected due to its advantages at capturing topography and mechanical properties in material. Results illustrated the ability of AFM to obtain the mechanical properties (modulus) of individual mineral components in shale, the detailed topography of crack, and mechanical properties of minerals in a specific area. In particular, the mechanical properties of minerals around crack explained the layered distribution of minerals around the fractures, and the cracks developed in the clay mineral layer was detected. This article demonstrates the great potential application of AFM in shale.

Microcracking behavior and damage mechanism of granite subjected to high temperature based on CT-GBM numerical simulation

Studying the high-temperature impact on microcracking behavior of granite is of great significance to geothermal energy extraction and deep engineering disaster prevention. Therefore, a thermo-mechanical coupled numerical model of granite is established based on computed tomography and grain-based model (CT-GBM) to investigate the impact of high temperature upon microcracking behavior of granite, and to further discuss the thermal damage mechanism. The results show that the thermal damage of granite mainly develops in the form of tensile failure. The development of intra grain cracks can be roughly divided into three periods featuring quiet (room temperature ∼ 300℃), stable development (300℃∼450℃) and unstable development (450℃∼600℃). The development of grain boundary cracks first appeared at the feldspar-quartz grain boundary, but the feldspar-feldspar grain boundary cracks prevail at high temperature (above 332℃) due to the large proportion of feldspar in granite. The phenomenon of stress concentration in granite under high temperature becomes growingly obvious with the increase of temperature, and such phenomenon is more obvious in grain boundaries than in mineral grains, which is the reason of microcracking and prevail of grain boundary cracks. In addition, the thermal damage degree of mineral grains and grain boundaries is described quantitatively through the self-defined crack coefficient. It is discovered that under the joint influence of thermal expansion characteristics and mechanical properties of minerals, the damage of grain boundaries between different minerals is more serious than that in identical minerals, and the damage of quartz grain is more serious than that of feldspar and mica.

Comparative Study on Mineral-Scale Microcrack Propagation of Shale under Different Loading Methods

Producing a sufficient volume of multiscale crack networks is key to enhancing recovery of shale gas. The formation of crack network largely depends on initiation and propagation of microcracks. To reveal the influence of different loading methods on the propagation of mineral-scale microcracks, this study used the Voronoi tessellation technique to establish a cohesive zone model of shale mineral distribution and applied six different boundary conditions to represent different loading methods. Crack path characteristics, rupture characteristics, continuous crack propagation and turning, and en echelon intermittent crack propagation under different loading methods were compared and analyzed. The essence of different loading methods affecting the length and complexity of cracks was the spreading range of tensile microcracks. The mechanical properties of minerals led to dissimilarities in continuous crack propagation and turning. The formation and propagation of en echelon intermittent fractures of different scales were mainly impacted by the heterogeneity of minerals and mineral aggregates. The spreading direction and connection form of en echelon intermittent fractures were mainly affected by the loading method. Conclusions arising from mineral-scale simulations contribute to understanding the mechanism of microcrack propagation resulting from different loading methods, and these conclusions have a guiding significance to enhanced shale gas recovery.

Mechanical Characterization of Heterogeneous Polycrystalline Rocks Using Nanoindentation Method in Combination with Generalized Means Method

ABSTRACTThe mechanical characterization of rocks is important in engineering design and analysis of rock-related structures. In the current researches, rocks are classified as heterogeneous materials with anisotropic behavior, and advanced methods such as combined experimental-numerical approach are developed to characterize the behavior of rocks. In this study, the nanoindentation experiment in conjunction with the generalized means method is used to determine the Young’s modulus and hardness of eight different polycrystalline granite rocks. In the first step, the Young’s modulus and hardness of granites’ constituents are determined through nanoindentation tests on pure granite minerals. Then, the properties of granites are determined using generalized means method by considering the mechanical properties of minerals, their volume fractions and an empirical constant called the microstructural coefficient. Accurate results with less than 3% error are obtained for 62.5% of the granite samples. The generalized means is introduced as a simple and effective method to characterize the mechanical properties of heterogeneous polycrystalline rocks.

Effects of mineral composition on the fracture propagation of tight sandstones in the Zizhou area, east Ordos Basin, China

To reveal the effect of mineral composition on fracture propagation of sandstones, a series of experiments were performed on quartz arenite and sublitharenite. Two fracture propagation mechanisms were identified in sandstones: intragranular and intergranular fractures. As determined by the mechanical properties of minerals, grain fracturing occurred in a majority of detrital quartz and a small amount of quartz cement, feldspars and carbonate cement, exhibiting typical brittle behavior and forming intragranular fractures. Due to the residual space between brittle detrital grains, which act as “flaws” in the sandstones that could initiate a stress concentration, the intergranular fractures occurred only between brittle grains. As cement are situated at the contact locations between detrital grains, mechanical properties and the occurrence of cement played an important role in intergranular fracture propagation. No intergranular fractures occurred between detrital quartz cemented by clay or carbonate, while quartz overgrowths did not hinder the propagation of intergranular fractures.

Efficiency of X-ray radiometric separation in preliminary concentration of ore

One of the efficient approaches to improvement of mineral processing technologies is the enhancement of ore pre-treatment with preliminary concentration. A promising dressing technique is X-ray fluorescent separation applied to various minerals to date. This process efficiency depends on various factors connected with characteristics of minerals to be processed, dressability of minerals in the preliminary concentration, geological characteristics, physical and mechanical properties of minerals, specifics of the pre-treatment circuits and modes, as well as with features of X-ray fluorescent separation. The research is aimed to study the influence of the factors which govern expediency and application condition of X-ray fluorescent separation for the preliminary concentration of mineral raw materials. The research methods were modeling of hypothetical ore grading with respect to the content of ore components with plotting of limit curves of separation, testing on X-ray fluorescent separator SRF-100L, theoretical analysis of formulas for calculating ultimate dressability indices as well as analytical calculations of particle size distribution and quality of complex ore separation by the ore separation plant circuit. The research has found that efficiency of the preliminary concentration grows with the lower content of useful component in raw material and with higher degree of dissociation of this component. Efficiency of using ore separation plant circuit in the preliminary concentration depends on the ore hardness and on drilling-and-blasting design, as well as on the circuit and modes of crushing and screening at the ore separation plant, including the number of the machine sorting classes accepted in the circuit. The preliminary concentration technologies with X-ray fluorescent separation should be developed with regard to the influence exerted on the ore separation efficiency by the material constitution of ore and dissociation of mineral phases to sizes suitable for the preliminary concentration, grain size composition of the material before separation, which depends on the parameters of mining, drilling-and-blasting and pre-treatment with crushing and screening, as well as on the ore separation plant circuit and machine sorting classes. The research results are applicable to development of the preliminary ore concentration technologies with X-ray fluorescent separation

Effect of Thermal Treatment on the Basic Friction Angle of Rock Joint

There is a growing demand of knowledge on the behavior of rock masses after thermal treatment in both academic and practical aspects due to the high demand of construction of underground structures under the high-temperature environment. The peak shear strength of rock joints has a significant role in evaluating the stability problems of surrounding rocks. However, there is a lack of information about the temperature-dependent nature of the basic friction angle of rock joints, which serves as an essential parameter to evaluate the peak shear strength. The present study experimentally investigates the influences of temperature magnitude (20, 200, 400, 600, and 800 °C) on the basic friction angle of granite, marble, and red sandstone joints. The basic friction angles of the three kinds of rock joints exhibit linear trends with the increase in the treatment temperature. The basic friction angles of granite and red sandstone joints increase with the increase in the treatment temperature, while the values for marble joints continually decrease. The mechanisms for the thermally altered variations in the basic friction angle of rock joint are mainly related to dehydration process, uneven expansion of mineral grains, thermally weakened asperities distributed on the surfaces, and change in physical and mechanical properties of minerals. In addition, other test conditions, including tilting rate, specimen size, repetition number, and cooling rate, are also analyzed. The present study provides useful data in establishing a peak shear strength criterion for rock joints by considering the temperature effect.

3D Microstructure and Micromechanical Properties of Minerals in Vanadium-Titanium Sinter

Abstract To investigate the structural characteristics and mechanical properties of minerals in vanadium-titanium sinter, the 3D microstructures of the sinter were reconstructed by serial sectioning in conjunction with computer-aided 3D reconstruction techniques The results show that hematite and magnetite in vanadium-titanium sinter will grow along the longitudinal axis direction and act as a scaffold. The size of magnetite crystals in vanadium-titanium sinter is much smaller than that in traditional sinter. The calcium ferrite in vanadium-titanium sinter is columnar-like, while that in traditional sinter is needle-like. The decreasing order of the microhardness value of minerals in the two sinters is hematite, calcium ferrite, magnetite and silicate, while the fracture toughness value from highest to lowest is calcium ferrite, hematite, magnetite and silicate. The comprehensive hardness value and comprehensive fracture toughness value of vanadium-titanium sinter are both less than these of traditional sinter.

Energy characteristics of finely dispersed rock systems

In their genesis, rocks accumulate their energy potential – free energy of rock-forming minerals and the rock in general that is an important criterion of raw material genetic classification for construction materials production. The free energy value for the macrostate of a substance (rock) is atomization energy. The critical surface tension value can be used as an energy characteristic for destroyed rock in a finely dispersed state. If condensed phase surfaces carry no significant electrostatic charge, then main surface forces that determine the interaction between solids are dispersion ones evaluated by the Hamaker constant value. These energy parameters can enable forecasting various physical and mechanical properties of minerals and rocks and thereby increase the efficiency of construction materials production where synthesis is based on the complete rock destruction. Since compared chemical compositions of minerals forming rocks revealed a predominant silicon dioxide content in them, the aim of this paper was to establish a possible relationship between the silicon dioxide content and energy characteristics for finely dispersed rock systems of various genetic types. The selected objects of research were different genesis rocks typically used in the construction materials industry and quartz as a main rock-forming mineral. Test samples of rocks in a finely dispersed state were obtained by dry milling. It is established that an increase in silicon dioxide content in the limestone – quartz series leads to higher atomization energy, specific mass atomization energy and free surface energy with intensified dispersion interaction between particles evaluated by an increase in the Hamaker constant.

A physical basis for the frictional melting of some rock-forming minerals

Under conditions of coseismic slip (0.1–2.0 m s −1) within the upper crust, differences in the shear yield strengths, fracture toughnesses, melting points and, to a lesser extent, thermal conductivities of rock-forming minerals result in a hierarchy of friction melting susceptibilities. In many so-called pseudotachylytes it is observed that phyllosilicates and amphiboles are preferentially consumed to form the melt phase, whilst quartz and feldspar tend to survive as clasts. This can be explained in terms of the disequilibrium “flash” melting of those mineral phases possessing the lower shear yield strengths, fracture toughnesses and thermal conductivities rather than by eutectic melting that would otherwise generate equilibrium minimum melts indicative of igneous processes. At high strain rates typical of coseismic faulting, the mechanical behaviour of minerals is primarily controlled by their fracture toughnesses, with progressive comminution during slip leading to fusion. The friction melting dependence on the mechanical properties of minerals indicates that there may be an important relationship between wall-rock lithology and earthquake magnitude if frictional melting results in fault lubrication.

The effect of hydrogen on oxygen diffusion in quartz: evidence for fast proton transients?

The importance of water in modifying the physico-chemical and mechanical properties of minerals has long been recognized. Water dramatically weakens quartz and enhances oxygen diffusion in silicates at high pressures and temperatures, with important geological consequences, but the underlying mechanisms are poorly understood. Recent attention has focused on the role of H2 and O2 in these mechanisms. Here we report the results of a study of the diffusion of oxygen in quartz at high pressure and temperature in the presence of water and of dry H2 gas, and compare the results with those of experiments in the presence of dry O2 gas. We conclude that oxygen diffusion is inhibited in the presence of dry H2 but enhanced in the presence of H2O, and deduce that fast H+ transients rather than H2 movement may be responsible for oxygen diffusion enhancement in framework silicates. Because of their high mobility, such transients may well be experimentally unquenchable within the silicate framework.