Natural Granite Research Articles

Trace element (Be, Zn, Ga, Rb, Nb, Cs, Ta, W) partitioning between mica and Li-rich granitic melt: Experimental approach and implications for W mineralization

Mica is the most important carrier of rare alkalis (Li, Rb and Cs) and volatiles, and also a major host of rare metals such as Sn, W, Nb and Ta. Thus, the knowledge of trace element partitioning between mica and silicate melt is crucial to understand enrichment mechanisms of ore metals in evolved silicic systems. However, experimental data are scarce, mainly because the synthesis of large mica grains which can be analyzed with laser ablation techniques is challenging. To address this issue, we conducted two-step experiments, using a high-temperature step at 800 °C, and a low-temperature step at 600 °C with a temperature cycling interval of 30 °C, and variable run durations from 21 to 60 days. The experimental products, at 600 °C, 200 MPa, are mainly composed of mica and alkali feldspars. Ferroholmquistite (Fhlm; a Li-bearing amphibole) was also observed in the Li-bearing systems.Beryllium, Zn and Cs are highly incompatible in all run products with mineral/melt partitioning of mineral/meltDBe between 0.01 and 0.08, mineral/meltDZn between < 0.01 and 0.24 and mineral/meltDCs between <0.01 and 0.19. Gallium is mildly incompatible in mica and feldspars with mica/meltDGa, K-feld/meltDGa and Na-feld/meltDGa of 0.24–0.35, 0.60–0.67 and 0.69–0.72, respectively, whereas Fhlm/meltDGa is nearly 1. Rubidium is characterized by a slight enrichment in mica and K-rich feldspar with respect to melt. Niobium and Ta are highly incompatible in feldspars, while they are compatible in ferroholmquistite. Li-mica crystallization would cause Nb/Ta fractionation with mica/meltDNb and mica/meltDTa of 4.46 and 0.88, respectively. Tungsten is preferentially incorporated in Li-rich mica with mica/meltDW > 22. The strong partitioning of W into Li-rich mica implies that minor Li-rich mica fractionation (>5 %) will strongly deplete W in the residual melt, thus inhibiting transfer to the magmatic fluid at the magmatic-hydrothermal transition. Based on the observed mineral/meltD value, a multi-stage quantitative fractionation model for the behavior of metals during the crystallization of Li-bearing granitic magmas was developed. The results suggest that crystal fractionation is an effective mechanism that could further enrich Be, Ga, Rb, Cs, Nb and Ta in residual melts. Li-rich mica and muscovite are more effective in causing Nb/Ta fractionation as compared with biotite. The very low Nb/Ta ratios found in natural granite may have resulted via extreme, i.e., >99 wt% of fractional crystallization, even if without the precipitation of columbite-group minerals or increasing hydrothermal activity. Due to the very high Li-mica/meltDW value, water saturation in the melt and subsequent magmatic fluid exsolution should occur before Li-mica starts to crystallize to avoid W sequestration in the magma. At 175 MPa, the efficiency of extracting W from Li-poor granitic system is at least 15 % higher than that from Li-rich granitic system. Li-poor granitic systems are thus expected to have a greater W-mineralization potential than Li-rich system, which is consistent with the fact that most parental magmas of large/giant W deposits are Li-poor in composition.

Plastic deformation effect on contact behaviour in granular materials

Contact tests on machined and natural granite showed that extensive plastic deformation which extends to the core shape is happening before the cross-over from the behaviour of an elastic rough surface to the Hertzian behaviour of an elastic smooth contact when all asperities have yielded in the surface. The plastic deformation, which was found to take place when the estimated maximum stresses at the contact reaches about 0.6 of the material hardness, affects the behaviour during normal loading as the material will start to deform at constant stiffness after reaching these stresses. The plastic deformation during lateral loading also affects the applicability of lateral loading models. The data yielded a much lower lateral stiffness which is around one order of magnitude less than that predicted by the available contact models.

Study on phase evolution and mechanical properties of reconstructed granite

In this paper, reconstructed granite with enhanced mechanical properties is prepared by re-melting and re-sintering granite wastes based on the formation process of natural granite. The sintering process, phase composition, and mechanical properties are deeply investigated. The optimal synthesizing process is sintering granite wastes at 1090 °C for 2 h with a preloading pressure of 25 MPa. Reconstruction results in excellent mechanical properties with a Vickers hardness of 5.30 GPa, a bending strength of 64.84 MPa, and an elastic modulus of 68.77 GPa, which are superior to those of natural granite (Vickers hardness of 3.64 GPa, bending strength of 23.40 MPa, and elastic modulus of 58.77 GPa). The sintering process plays a decisive role in improving the mechanical properties, which not only regulate the phase composition and refine the grain size but also effectively decrease the formation of cracks. This work not only clarified the mechanism between the phase evolution and mechanical properties of reconstructed granite but also proposed a viable way to dispose granite wastes for natural resource recycling.

Structure and performance sensitivity to simulated An4+ waste doping in a high-silicon glasses-ceramics

Inspired by the long-term stability of natural radioactive rocks, a kind of high-silicon granite has been proposed as a potential aluminosilicate glass-ceramics matrix for actinide waste disposal. With the characteristic of secondary diagenesis, the loading capacity of the natural granite to simulated waste (CeO2) is 8 wt.%, reached through doping induced O/Si ratio increase. By adjusting the critical Al/Si ratio in the matrix, the loading capacity increases to 20 wt.%. Both the reductive Fe3O4 and thermal defects in CeO2 cause the valence change of Ce in the reaction. As a charge compensator, most Ce ions were hidden in a shelf-like aluminosilicate glass network, while part of reduced Ce ions exists in Ce2Si2O7 ceramic.

Experimental Evidence for Shear‐Induced Melting and Generation of Stishovite in Granite at Low (&lt;18 GPa) Shock Pressure

AbstractKnowledge of the shock behavior of planetary materials is essential to interpret shock metamorphism documented in rocks at hypervelocity impact structures on Earth, in meteorites, and in samples retrieved in space missions. Although our understanding of shock metamorphism has improved considerably within the last decades, the effects of friction and plastic deformation on shock metamorphism of complex, polycrystalline, non‐porous rocks are poorly constrained. Here, we report on shock‐recovery experiments in which natural granite was dynamically compressed to 0.5–18 GPa by singular, hemispherically decaying shock fronts. We then combine petrographic observations of shocked samples that retained their pre‐impact stratigraphy with distributions of peak pressures, temperatures, and volumetric strain rates obtained from numerical modeling to systematically investigate progressive shock metamorphism of granite. We find that the progressive shock metamorphism of granite observed here is mainly consistent with current classification schemes. However, we also find that intense shear deformation during shock compression and release causes the formation of highly localized melt veins at peak pressures as low as 6 GPa, which is an order of magnitude lower than currently thought. We also find that melt veins formed in quartz grains compressed to &gt;10–12 GPa contain the high‐pressure silica polymorph stishovite. Our results illustrate the significance of shear and plastic deformation during hypervelocity impact and bear on our understanding of how melt veins containing high‐pressure polymorphs form in moderately shocked terrestrial impactites or meteorites.

Multiscale structural characterizations of anisotropic natural granite residual soil

While the anisotropy of sedimentary soil—particularly the underlying role of soil structure—is well understood, similar knowledge about granite residual soil formed by weathering is scarce. In particular, the evolution of soil structure during the hollow cylinder torsional shear tests (among the most appropriate for studying soil strength anisotropy) remains largely unknown. This study systematically investigates the multiscale structural properties of granite residual soil using stereo microscopy, scanning electron microscopy, energy-dispersive spectrometry, and computed tomography. Furthermore, the structural evolution during hollow cylinder torsional shear tests is traced. Results indicate the strength anisotropy of residual soil is associated with horizontal fissures which cause low shear strength when the soil is sheared with a principal stress direction of 45°. The cementation via Fe is characterized by a uniform distribution. Different evolutionary patterns are observed for soils within the shear band, inside the necking area, and in other regions. It is not always the case that particles are rearranged with their long axis perpendicular to the major principal stress. This study improves the understanding of natural residual soil structure and provides some insights into its anisotropic behavior.

Steel furnace slag aggregate for railway ballast: assessment of abrasion evolution by close-range photogrammetry

Electric Arc Furnace steel slag aggregate has potential for wider application in transport infrastructures. However, the use of steel slag aggregate in the railway ballast layer, as an alternative to natural high quality crushed rock, is still restricted in some countries. This is not consistent with the current sustainable construction paradigm. To demonstrate the potential of this material, in this study the authors characterized its morphology and performance, carrying out quantitative analyses on the abrasion and 3D morphology evolution of particles submitted to micro-Deval testing. The slag particles showed higher angularity and surface texture indices than a natural granite used as reference; retained these characteristics longer; and yielded comparable or lower surface wear. These findings support the potential use of slag aggregate as an alternative to railway ballast material.

A natural granite based glass-ceramics matrix for immobilizing simulated An3+ waste

Based on the chemical composition and secondary diagenetic property, one type of natural aluminosilicate was proposed as an immobilization matrix for the simulated An3+ waste (Nd2O3). The results show that sintering at 1500 °C for 6 h can be used as a prerequisite for the preparation of the waste form. The loading content of Nd2O3 in the waste form dominated by the glass-ceramic structure can reach 16 wt.%. In this system, as a glass modifier, Nd2O3 improves the mechanical properties of the sample by adjusting the density of Si-O skeleton or by participating in the construction of glass-ceramics. Among them, Nd3+ attaches to the glass network as a charge compensator, or participates in the crystal. The normalized elemental release rate of Nd is maintained at the order of 10−5 or below, and approaches equilibrium after 28 days, indicating that the sample own considerable resistance to the harsh environment.

Experimental Crystallization of the Beauvoir Granite as a Model for the Evolution of Variscan Rare Metal Magmas

Abstract New experiments on the strongly peraluminous, Li-, P- and F-rich Beauvoir granite (Massif Central, France) provide a basis for understanding crystallization and chemical fractionation in Variscan rare metal magmas. Crystallization experiments were performed on two natural granite compositions under H2O-saturated conditions at 100, 200, and 300 MPa, from 540°C to 700°C and between ~NNO + 3 and NNO-1.4. Experimental charges were examined by SEM and their products (glasses and crystals) analyzed for major elements by EMPA. Trace element concentrations in selected glasses were determined by LA ICP-MS. Despite experimental durations commonly exceeding 1000 h and some up to 4000 h, kinetic problems were encountered in particular in the 100 MPa charges whereas, at 200 and 300 MPa, results consistent with previous melting experiments were obtained. Beauvoir melts crystallize quartz, plagioclase, K-feldspar and mica as major phases. At NNO-1.4, mica is a biotite, whereas it is a Li-mica between ~NNO+3 and NNO-1. Apatite, Fe-Ti oxides, either hematite or magnetite, topaz, amblygonite, cassiterite and columbite-tantalite appear as accessory phases between ~NNO + 3 and NNO + 1. Experimental plagioclases are albitic (An &amp;lt;4.5 mol%) and more Ca and K-rich than natural albites in the granite whereas experimental K-feldspars are more sodic (Ab &amp;lt;45 mol%) than the natural crystals. The less evolved starting melt crystallized Li phengites whereas the most evolved yielded Li-, F-rich micas near the polylithionite-zinnwaldite series, similar to natural micas in the granite. Equilibrium crystallization increases A/CNK, F and P and concentrates Li, Be, B, Rb, Cs, W, U in the melt. Nb and Ta are also enriched, their behavior being controlled by the solubility of columbite-tantalite in the melt. Other elements are either unchanged (Mn, Zn, Ti) or depleted (Sr, Pb) during magmatic fractionation. Sn is concentrated in Li-mica and hematite, and it behaves compatibly at high fO2. Beauvoir melts crystallize at very low temperatures, below 670°C for the two compositions studied and solidus temperatures, determined from previous melting experiments and confirmed by the new crystallization experiments, are near 550°C. The experiments demonstrate that most of the mineralogical and geochemical characteristics that make the Beauvoir granite distinctive result from magmatic rather than hydrothermal post-magmatic processes. Albitic plagioclase, Li-mica, topaz, and amblygonite are of magmatic origin. Glass major element compositions suggest that the two granite samples represent crystallized liquids. Trace element fractionations for most elements at Beauvoir can be accounted for by magmatic crystallization–differentiation processes. Implications for the mineralogy, fO2, volatile concentrations, crystallization and conditions of emplacement, fractionation mechanisms and origin of the Beauvoir granite are discussed.

Sosialisasi Strategi Bisnis Menggunakan Business Model Canvas (BMC) Pada Perusahaan Konstruksi

CV. Marga Jaya Properti started its business in marble, natural granite, granite tile, traso, wood interior and developed in the field of construction services such as construction and renovation services for residential houses, hospitals and places of worship. The high business competition makes it difficult for companies to market which results are decreased sales and decreased production. This activity aims to analyze the business in order to overcome these problems by socializing the business model design using the Business Model Canvas (BMC) method. The BMC method is carried out by observation, literature study and Focus Group Discussion (FGD) between the Team and the experts. Companies must increase marketing activities, increase product added value and increase partnerships. Marketing activities should be carried out both online and offline. Online marketing can be added through online buying and selling forums, google ads, tik tok shop, twitter, email or telegram, while offline marketing can be added by participating in property exhibitions, distributing brochures, holding property webinars, and inviting customer to become marketing. The increase in added value can be done by free consultations for construction service, free delivery product for Bekasi area. The increase partnerships is by adding developers such as developers for handling electricity, water and so on in working on large projects, for example the construction of hospitals. The results of this Activity that are felt by owners and employees are their increased knowledge of business models which can increase marketing, increase sales and increase production.

Ceramic granite production wastes use for enhancement asphalt concrete construction and technical properties

Bitumen concrete construction and technical properties improvement when used as refuse finely-fragmented layer inorganic material formed in production of ceramic granite, ceramic construction material, is conditioned by its phase composition and structure. The set of physicochemical studies has established that the high physical and technical properties of ceramic granite are associated with its microstructure, which presents glassceramic composite consisting of amorphous glass phase permeated with mullite crystals and silica-containing phases of quartz and cristobalite, that provides low material porosity. The density of natural granite containing only β-quartz in an amount of about 35% with its density and the density of other minerals in the granite, in particular field spars, is 2.6… 2.7 g/cm3. The density of ceramic granite decreases due to less dense β-cristobalite, but at the same time its porosity decreases due to glass crystal structure. Use of non-porous refuses of ceramic granite as finely-fragmented inorganic material reduces amount of bitumen in bitumen concrete mixture, increases water resistance, compressive strength, shear resistance of bitumen concrete, which can increase service life of road surface.

Laboratory Hydraulic Fracturing of Large-Scale Granite Characterized by Acoustic Emission Under Different Confining Conditions

Hydraulic fracturing (HF) technology is crucial to form connected fracture network within the low-permeability geothermal reservoir. However, the HF process and failure mechanism in this process are only partly understood. A series of true triaxial hydraulic fracturing tests on large-scale natural granite samples were conducted under different confining conditions, combining with acoustic emission monitoring to evaluate the initiation and propagation of hydraulic fractures. Results show that a main hydro-fracture was formed in three samples during the first fracturing process. Many AE events occurred during the first pump period. The proportion of tensile fractures during the hydraulic fracturing accounted for more than 85% of all fractures. The test results could provide a new understanding of the effect of HF under different stress conditions. And implied that field engineering should pay attention to the initial HF, which may determine the main fracture framework of the field at the first pump procedure.

Preventive maintenance and silica exposure limits integrated in the production planning of a granite processing unit

PurposeThis paper studies the integration of production and maintenance planning for an unreliable production system subject to gradual deterioration. The goal of this planning is to optimize production and maintenance while reducing workers' exposure to silica dust. The objective will therefore be to offer manufacturers a production strategy that minimizes the total cost of production while considering the health of employees.Design/methodology/approachAdequate prevention methods are determined and integrated into the granite transformation production system, which evolves in a stochastic environment. With the failure rate of the dust reduction unit being a function of its degradation state, the authors solve the optimization problem using stochastic dynamic programming in the context of nonhomogeneous Markov chain.FindingsThe resulting planning strategy shows that one can manage stock optimally while ensuring a healthy environment for workers. It ensures that crystalline silica prevention equipment is available and effective and defines the production rate according to a critical threshold, which is a function of the age of the dust reduction unit.Research limitations/implicationsThis article illustrates that it is possible to integrate silica dust reduction measures into production planning while remaining optimal and ensuring the health of operators. In the present study, the machined granite was assumed to be a natural granite, and production takes place in a closed environment.Originality/valueThe originality of this work lies in its development of an optimal joint production and maintenance strategy, which considers limits of exposure to crystalline silica. An optimal production and maintenance control policy considering employees' health is therefore proposed.

Characterisation of dust emissions from machined engineered stones to understand the hazard for accelerated silicosis

Engineered stones are novel construction materials associated with a recent upsurge in silicosis cases among workers in the stonemason industry. In order to understand the hazard for the short latency of lung disease among stonemasons, we simulated real-time dust exposure scenario by dry-machining engineered stones in controlled conditions, capturing and analysing the respirable dust generated for physical and chemical characteristics. Natural granite and marble were included for comparison. Cutting engineered stones generated high concentrations of very fine particles (< 1 µm) with > 80% respirable crystalline silica content, in the form of quartz and cristobalite. Engineered stones also contained 8–20% resin and 1–8% by weight metal elements. In comparison, natural stones had far lower respirable crystalline silica (4- 30%) and much higher metal content, 29–37%. Natural stone dust emissions also had a smaller surface area than engineered stone, as well as lower surface charge. This study highlighted the physical and chemical variability within engineered stone types as well as between engineered and natural stones. This information will ultimately help understand the unique hazard posed by engineered stone fabrication work and help guide the development of specific engineering control measures targeting lower exposure to respirable crystalline silica.

High immobilizing capacity of natural granite as glass-ceramic matrix to simulated trivalent actinide waste

One kind of natural granite was selected as matrix for loading simulated trivalent actinide waste (Nd2O3) in an attempt to solve the two major problems of nuclear waste and granite waste simultaneously. The results show that the introduced waste ion plays an important role in the structure change of the matrix. After traditional sintering at 1300 °C for 60 min, the granite was a glass-ceramic structure without nuclear waste doping. With 10 mass % of waste doping, the introduced Nd3+ entered the final waste form, the bulk transformed to completely vitrified. With further waste doping, Nd3+ also entered into the crystal lattice and Nd related compounds grew gradually. Nd was uniformly distributed in the final waste form under the maximum doping amount (76 mass %) in the natural granite. The final waste form has enhanced physical stability. The Vickers hardness and density of the samples increased from 6.79 to 10.08 GPa and from 2.11 to 4.13 g cm−3 with the doping of Nd2O3, respectively. This may be a potential way to dispose both granite waste and nuclear waste.

Unveiling the mystery of scale dependence of surface roughness of natural rock joints

Scale dependence of surface roughness of natural rock joints has long been an outstanding issue in rock mechanics. Controversial results were reported by various studies; however, the nature of scale dependency and the underlying mechanism for the conflicting observations remain unclear. Rock joints at different scales characterise two-order asperities, namely, waviness and unevenness; thus understanding how the individual roughness of waviness and unevenness vary as the joint size increases from the laboratory-scale to the large-scale is crucial for revealing the scale effect mystery. Here we digitise three natural granite joint surfaces with the same dimension of 1000 mm × 1000 mm through a high-resolution, three-dimensional scanner. Waviness and unevenness of each rock joint surface are quantitatively separated by selecting an appropriate sampling interval. The respective fractal dimensions of waviness and unevenness of joint surfaces sized from 100 mm × 100 mm to 1000 mm × 1000 mm are estimated through an improved roughness-length method. We find that the fractal dimensions of two-order roughness are scale-dependent but without generalised trends. The stationarity threshold beyond which the scale-dependency of roughness vanishes is absent for all the three joint samples, suggesting that the roughness of natural rock joints be assessed at the specific scale of the rock mass in-situ. We reveal that previous controversial results regarding scale effect are likely due to the composition of the roughness scaling of waviness and unevenness. Thus, accurate stability analysis of rock-engineering projects should consider separate contributions of multi-order asperities across scales to the strength and deformation of jointed rock masses.

Dynamic Compression Characteristics and Failure Mechanism of Water-Saturated Granite

For Fangshan granite in Beijing, the static compression and dynamic compression tests have been carried out separately under natural air drying and water saturation. It was found that the dynamic compressive strength of water-saturated granite is higher than that of air-dried granite, which is contrary to the result that the strength of water-saturated rock is lower than that of air-dried granite under static load. Furthermore, under the medium strain rate condition, when the strain rate is 85 s−1, the dynamic strength of natural air-dried granite could be increased by nearly 0.5 times compared with its static state. The dynamic strength of water-saturated granite could be increased by nearly 1–2 times compared with its static strength, which shows that water-saturated granite has stronger strain rate sensitivity than natural air-dried granite. Meanwhile, under impact loading, from the perspective of water-bearing granite the Bernoulli effect of fluid, the adhesion effect of free water and the Stefan effect of fluid in water-saturated granite were revealed, and found to be the essential reasons affecting the dynamic strength of water-saturated granite. The dynamic strength in different water-bearing states in the range of medium strain rate could then be analyzed in depth, providing a certain reference value for the strength design of water-bearing rock engineering.

Quantifying the Abundances of Minerals of Granitic Composition Using the Hapke Model of Bidirectional Reflectance

Quantitatively assessing the abundances of the composite minerals in terrestrial granite is crucial to understanding the evolutionary history of the earth’s crust and to mineral exploration as well. Prevalent methods of estimating mineral abundances based on the Hapke model by setting the optical constants of the endmembers ahead of time are no longer applicable to terrestrial granite because of the complexity of natural granite, which leads to remarkable uncertainties in these estimations. In this study, we retrieved specific photometric parameters from the bidirectional reflectance spectra measured at a range of incidence, emergence, and phase angles before they were input into the Hapke model and used to estimate the mineral abundances. Four types of granite samples containing the main granitic minerals (quartz, alkali feldspar, and plagioclase) were used to test the effectiveness of our proposed method. The effects of the particle size and dark minerals on the inversion results using the visible near and shortwave infrared (VNIR-SWIR) wavelengths were also examined. The results show that using the photometric parameters retrieved from multiangle measurements as inputs to the Hapke model can produce accurate estimations of the abundances of quartz, alkali feldspar, and plagioclase in both natural and synthetic granite samples. Furthermore, the results demonstrate that the retrieved particle sizes of the particulate samples are close to the ground measurements. Thus, the proposed approach provides a more accurate and efficient estimation of the compositions of terrestrial granites, making it feasible to quickly assess the abundances of the minerals contained in granite.

An investigation on the deterioration of physical and mechanical properties of granite after cyclic thermal shock

As one of the main thermal storage medium of hot dry rock geothermal resources, granite is often subject to frequent thermal shock during the geothermal exploitation. Grasping the response regularity of granite to thermal shock is of great significance to the construction and long-term reliability evaluation of enhanced geothermal system (EGS). This paper investigated the physical and mechanical properties of granite after 0∼20 thermal shocks, and discussed its internal deterioration mechanism. Combined with ANSYS numerical simulation analysis, the mechanical formation mechanism of thermal cracks that lead to the deterioration of physical and mechanical properties of granite was analyzed. The results show that the first thermal shock tends to cause the severest deterioration to both physical and mechanical properties of granite. But when the number of thermal shocks exceeds 10, the deterioration slows down. The increase in contact thermal resistance between mineral particles after cyclic thermal shock results in a decrease in the thermal conductivity of granite. The enhancement of local stress concentration effect and the increase of local bearing capacity difference of granite after cyclic thermal shock result in the decrease of peak strength and the enhancement of ductility characteristics of granite. Due to the existence of thermal cracks, the granite after cyclic thermal shock has one more path to release the energy stored during the loading process than the natural granite. Therefore, the maximum counts at the beginning of crack propagation and the entire crack propagation stage are smaller than that of the natural granite. During the thermal shock, the huge instantaneous temperature difference between the interior and exterior of granite leads to the formation of thermal stress, which increases rapidly and then disappears gradually. As a result, the interior of granite mainly bears the effect of the vertical compressive thermal stress up to 7.59 MPa, while the exterior of granite mainly bears the effect of vertical tensile thermal stress up to 9.18 MPa. The propagation of some pre-existing micro cracks with proper orientation in the interior of granite and the initiation and propagation of secondary thermal cracks on granite surface are identified as two main causes to the deterioration of the physical and mechanical properties of granite after cyclic thermal shock.

Immobilize CeO2 as simulated nuclear waste in natural magmatic granite: maximum solid solubility

Immobilize CeO2 as simulated nuclear waste in natural magmatic granite: maximum solid solubility