Quartz Sand Samples Research Articles

Research on 4N8 High-Purity Quartz Purification Technology Prepared Using Vein Quartz from Pakistan

This study investigates the potential of two quartz vein ores from the Hunza District, Gilgit-Baltistan, Pakistan, as raw materials to obtain 4N8 high-purity quartz (HPQ) sand. Various quartz purification processes were examined, including ore calcination, water quenching, flotation, sand calcination, acid leaching, and chlorination roasting. Analytical techniques such as optical microscopy, Raman spectroscopy, and inductively coupled plasma spectroscopy were employed to analyze the microstructure, inclusion characteristics, and chemical composition of both the quartz raw ore and the processed quartz sand. Microscopic observation reveals that the PK-AML quartz raw ore has relatively high purity, the secondary fluid inclusions are arranged in a directional–linear manner or developed along crystal micro-cracks, and most intracrystalline regions exhibit low inclusion contents, while the PK-JTLT quartz raw ore contains a certain number of melt inclusions. The two processed quartz sand samples exhibit a smooth surface with extremely low fluid inclusion content. A comparative analysis of different purification processes shows that quartz sand calcination has a higher impurity removal rate than ore calcination. After crushing the raw ore into sand, the particles become finer with a larger specific surface area. Quartz sand calcination maximally exposes the inclusions and lattice impurity elements within the quartz, facilitating subsequent impurity removal through acid leaching. Following the processes of crushing, ultrasonic desliming, flotation, sand calcination, water quenching, acid leaching, and chlorination roasting, the SiO2 content of PK-AML processed quartz sand is 99.998 wt.%, with only a small amount of Ti and Li remaining, and a total impurity element content of 20.83 µg·g−1. This meets the standard requirements for crucible preparation in industrial applications, making this vein quartz suitable for producing high-end HPQ products. In contrast, the overall purity of PK-JTLT quartz is lower, and the high contents of impurity elements such as Li, Al, and Ti are difficult to remove via purification experiments. The SiO2 content of PK-JTLT processed quartz sand is 99.991 wt.%, which is applied to higher-quality glass products such as photovoltaic glass, electronic glass, and optical glass, thus presenting broad prospects for application.

Diffraction, spectroscopic and microscopic studies of the sand from the amber deposit

QUARTZ sand plays a crucial role in the production of float glass, as it is the main source of silicon dioxide, which is necessary for the production of glass. The research was conducted on two samples of QUARTZ sand from the Oleksiivka amber deposit. The aim of this study was to investigate the morphology and chemical composition of QUARTZ sand samples. The identification methods such as infrared spectroscopy, X-ray diffraction, and electron microscopy with the Energy Dispersive X-ray Spectrometer detector were presented. Applied methods allowed to identify crystalline phases and non-crystalline components of the tested samples.

Understanding the effects of permafrost degradation through a multiphysics approach

Permafrost is a multiphase porous media that can host matter in all three states (solid, liquid, and gas). The equilibrium between the states of matter within the pore space is largely driven by salinity, pressure, and temperature. The complex interactions between the different thermodynamic processes can lead to a complex pore system that is altered at each subsequent thaw and freeze cycle. The dynamic changes imposed on this porous media alter the mechanical and electrical properties of the samples. These changes can thus be quantified and monitored using ultrasonic and electrical resistivity measurements. The experimental results presented in this work document the impacts of a thawing event on unconsolidated quartz sand samples that are partially saturated with a brine solution. The electrical resistivity and ultrasonic data are acquired simultaneously throughout the experiment, and the spatiotemporal changes within the solid matrix are captured by time-lapse X-ray computed tomography (CT). A total of 39 different samples are investigated. The two independent variables chosen for this study are the grain size and the salinity of the brines. The results indicate a clear transition in electrical and elastic properties as the material in the pore space transitions between two different states. Further results indicate that these transitions are the result of the alteration of the pore network itself. In addition, the study of P-wave velocity, ice fraction, and X-ray CT of two different types of ice that coexist within the pore network is documented. Given the distinct impact of two different types of ice on this cryogenic porous media, it is imperative to thoroughly comprehend the existence of different ice types before undertaking the electroelastic investigation of permafrost.

Experimental study on the influences of cutter geometry and material on scraper wear during shield TBM tunnelling in abrasive sandy ground

When shield TBM tunnelling in abrasive sandy ground, the rational design of cutter parameters is critical to reduce tool wear and improve tunnelling efficiency. However, the influence mechanism of cutter parameters on scraper wear remains unclear due to the lack of a reliable test method. Geometry and material optimisation are often based on subjective experience, which is unfavourable for improving scraper geological adaptability. In the present study, the newly developed WHU-SAT soil abrasion test was used to evaluate the variation in scraper wear with cutter geometry, material and hardness. The influence mechanism of cutter parameters on scraper wear has been revealed according to the scratch characteristics of the scraper surface. Cutter geometry and material parameters have been optimised to reduce scraper wear. The results indicate that the variation in scraper wear with cutter geometry is related to the cutting resistance, frictional resistance and stress distribution. An appropriate increase in the front angle (or back angle) reduces the cutting resistance (or frictional resistance), while an excessive increase in the front angle (or back angle) reduces the edge angle and causes stress concentration. The optimal front angle, back angle and edge angle for quartz sand samples are α = 25°, β = 10° and γ = 55°, respectively. The wear resistance of the modelled scrapers made of different metal materials is related to the chemical elements and microstructure. The wear resistances of the modelled scrapers made of 45#, 06Cr19Ni10, 42CrMo4 and 40CrNiMoA are 0.569, 0.661, 0.691 and 0.728 times those made of WC-Co, respectively. When the alloy hardness is less than 47 HRC (or greater than 58 HRC), scraper wear decreases slowly with increasing alloy hardness as the scratch depth of the particle asperity on the metal surface stabilizes at a high (or low) level. However, when the alloy hardness is between 47 HRC and 58 HRC, scraper wear decreases rapidly with increasing alloy hardness as the scratch depth transitions from high to low levels. The sensitive hardness interval and recommended hardness interval for quartz sand are [47, 58] and [58, 62], respectively. The present study provides a reference for optimising scraper parameters and improving cutterhead adaptability in abrasive sandy ground tunnelling.

Natural thermometers in concrete: Stability and reliability verification of inclusion decrepitation thermoacoustic thermometry

The fire-exposure temperature of concrete directly determines the degree of damage to its microstructure and the performance of concrete. Therefore, an accurate assessment of the fire-exposure temperature of concrete is crucial. But to date, there is not yet an accurate, practical, and effective method for measuring the internal temperature of concrete after fire. Based on the discovery that fluid inclusions in concrete act as natural thermometers, this paper investigates the scientific principles and experimental evidence of the decrepitation thermometry of inclusions. By extracting quartz sand samples from the interiors of concrete members after a fire and performing an inclusion decrepitation test on these samples, the maximum fire-exposure temperature of concrete can be determined with a high degree of accuracy. The test results reveal that the natural sand used in construction typically contains fluid inclusions, indicating that the necessary conditions for inclusion decrepitation thermometry are satisfied for concrete structures. In this study, standard quartz sand samples were configured, and inclusion decrepitation temperature measurements were conducted after subjecting the samples to different heating rates, cooling methods, thermostatic durations, and standing times after fire. The test results indicate that the impact of the aforementioned factors on the inclusion decrepitation temperature measurement is not evident. The maximum relative error between all temperature measurement results and the actual heating temperature is <10 %, and the average relative error is <2.5 %. The experimental results show that fluid inclusions are natural thermometers in concrete. After a fire, the maximum temperature experienced in the concrete can be quantitatively assessed using the initial decrepitation temperature of the inclusion. This method possesses the advantages of being a scientific test method and providing accurate temperature measurements without any indirect analysis or calculation using simple test equipment, sample preparation, and operation.

Experimental study on the effect of particle breakage on the shear characteristics of large-displacement soil exposed to heat treatment

Ring shear tests were performed in this study to investigate the large-displacement shear characteristics of quartz sand samples subjected to different degrees of volume effect and high temperature. The influencing principles of normal stress, temperature, and particle breakage on the large-displacement shear characteristics of the specimens were obtained. The influencing mechanism was further elucidated with reference to a previous study. On the basis of an analysis of the similarities and differences between the large-displacement shear behavior of samples before and after exposure to a temperature of 800 °C, we believe that samples impacted by temperature, particle breakage, and normal stress exhibit strain softening under large-displacement shear behavior that has an upper limit of approximately 600 kPa after heat treatment. Meanwhile, the high temperature affects the shear characteristics of the basal facies of a landslide by influencing the rock and soil breakage. The difference in the interlocking forces caused by the particle shape and breakage and the resulting fluctuation of the shear stress are further discussed.

Effects of membrane compliance on the normal-scale triaxial cyclic liquefaction test results of saturated coral sand

Correctly evaluating the membrane penetration and compliance effects in the element liquefaction test of saturated coral sand is important for test result applications. Therefore, the penetration volume measurement and triaxial cyclic liquefaction testing of saturated coral sand and quartz sand samples with the same grading and relative density were conducted for relatively loose and dense states, and the liquefaction resistance test results before and after membrane compliance correction were analyzed. The results showed that under the same conditions, the influence of the penetration and compliance of coral sand samples was more significant than that of the quartz sand samples. The general practice of ignoring the effect of membrane compliance in normal-scale triaxial tests is inapplicable in coral sand tests and will result in relatively unsafe analysis results.

Relationship between Induced Polarization Relaxation Time and Hydraulic Characteristics of Water-Bearing Sand

The induced polarization method has become a popular method for evaluating formation permeability characteristics in recent years because of its sensitivity to water and water-bearing porous media. In particular, the induced polarization relaxation time can reflect the macroscopic characteristics of the porous media of rock and soil. Therefore, in order to study the relationship between relaxation time and permeability, eight quartz sand samples of different grain sizes were used to simulate water-bearing sand layers under different geological conditions, and the induced polarization experiment and the Darcy seepage experiment were carried out on the same sand sample. The experimental results show that relaxation time and permeability are closely correlated with the grain size of quartz sand samples. According to the experimental data, the power function equation is a better fit for describing the relationship between permeability and relaxation time. It is worth noting that the equations obtained are only empirical equations for quartz sand samples, and they may not be applicable to all geological conditions.

Experimental study on the effect of particle size on the shear characteristics of large-displacement soil exposed to heat treatment: Shear fluctuation and heat degradation

The shear characteristics of soil on the basal face of a landslide body have important implications on landslide dynamics. In this study, ring-shear tests were carried out on quartz sand to study the shear characteristics of soil particle materials on the basal facies. Quartz sand samples of different particle sizes (0.25–1 mm) were treated at high temperature (20–800 °C) to determine the influence of temperature and particle size distribution (PSD) on their shear characteristics at different shear speeds. The shear characteristics of the samples were analyzed, including the shear stress, shear stress fluctuation, density variation, and degree of fragmentation. The results show that the amplitude of shear stress fluctuation increases with increasing shear velocity. It can be determined that the smaller the particle size, the greater the residual shear strength. Elevated temperature has a certain influence on the quartz sand and the shear characteristics (e.g., shear stress) exhibit a low degree of deterioration. The dilatancy and compaction mechanism of the samples under large displacement shearing is further discussed.

Breakage Characteristics of Quartz Sand Based on Ring Shear Tests: Implications for the Fragmentation Processes of Rock Avalanches

To investigate the effects of internal shear fragmentation on dry granular flow, in this study a series of ring shear tests were performed on quartz sand samples under different normal stresses (100 kPa, 200 kPa, and 300 kPa), shear displacements (3 m, 5 m, 10m, 15 m, and 20 m), and shear rates (30 deg min−1, 60 deg min−1, and 90 deg min−1). Next, the grain‐size distributions, fractal dimensions, and microcharacteristics of the quartz sand before and after the experiments were compared and analyzed. The study results show that grain breakage under shearing preferentially occurs at the edges of the particles and forms a bimodal distribution in frequency grain‐size distribution curves, which is consistent with observations of rock avalanches. The fine particles prevent the coarse particles from breaking, in turn leading to the ultimate grain‐size distribution and stable fractal dimension (2.61) of quartz sand at relatively small shear displacements compared with the travel distance of rock avalanches. The results of this study suggest that the fragmentation of rock avalanches during the shear spread stage may be far less significant than previously believed. Therefore, the fragmentation effect is not considered to be a major factor of the hypermobility in the late stage of rock avalanches.

A Study on Characteristics of Unsaturated Sandy Soils Based on the CT Scanning Method

In the hydrologic cycle, sandy soils play the role of a connecting reservoir of surface water and groundwater, particularly in arid areas. Therefore, to provide water conservation and ecological environment protection, it is important to study the soil water behavior in the unsaturated zone. At present, the CT-scan method is commonly used to study the soil hydraulic properties. In the field of materials science, the industrial CT high-resolution instruments are applied for quantitative research on the porous microstructure and fluid filtration law in sandy soils. In this study, we have studied five samples of sand scans of the quartz sand and CUGB coarse sand types. The industrial-type CT instrument XTH225ST was used for the sample microstructure scanning. In order to identify water: air, and solid particle distribution of the sample cross section, and to analyze the particle size distribution and moisture content, the scanned images were processed using the VG-Studio and ImageJ software. Comparing the CT-scan results of the four quartz sand samples, it can be concluded that the optimal particle size, ranges from 1 to 2 mm. According to the porosity quantitative analysis, with decrease in the particle size, the total porosity grate soil sample increases. After applying the image recognition and VG- Studio software, we can see that for different particle sizes of the sand sample, the average pore size increases with increase in the particle size. To study the moisture absorption and desorption phenomenon, two samples of the CUGB coarse sand are experimentally studied. The particle size of the samples range: from 1 to 2 mm. The CT scanning analysis is used to obtain the unsaturated characteristic curve of the soil when the moisture content reaches stability. Due to the lag phenomenon, the characteristic curve of the soil moisture has an obvious “loop,” or hysteresis, shape. As shown by a 3D modeling, the distribution of capillary water in the sand column is complex, and the water flow forms multiple winding paths, like “worms” creeping in the soil. The CT-scan method is used to overcome the limitations of the traditional experimental methods and to evaluate the relationship between the moisture content and the matrix suction. The obtained characteristic curve of soil moisture can be used to improve the efficiency of technological operations. The CT-scan method provides a new way of evaluating the water distribution characteristics of unsaturated soil.

Water resistance of structured sand-sodium-silicate mixtures

Purpose. To establish regularities of changes in sand-sodium-silicate mixtures (SSSM) relative water resistance, structured by steam-microwave solidification method (SMS), on their structuring parameters and sodium silicate solute (SSS) dissolution conditions. Methodology. Technical purity water, SSS with 2.83.0 silicate modulus, quartz sand with 0.23 mm average particle size were used in this work. Studies were carried out on quartz sand samples, which were preliminarily cladded with 0.52.5% (by weight) SSS and structured by SMS method. The fracture time of structured mixtures was evaluated on cubic specimens with 20 mm rib length, which were immersed in water at different temperatures. Findings. Changes in SSSM water resistance in water regularities depending on their manufacturing, use and storage conditions were established. Recommendations for SSSM rods removal from castings in water were developed. Originality. For the first time, it has been established that relative water resistance of the SSSM structured by SMS method decreases along with increase in water temperature in which it is destroyed. Depending on SSS mass used for quartz sand cladding in range 0.52.5%, water resistance dependence on treatment in steam-microwave environment with 27 minutes running time acquires an inversion character with inversion point `3.1 minutes into the processing. For the first time, it has been discovered that in boiling water the relative water resistance of SSSM, structured by SMS-process and having preheating, monotonically increases with preheating temperature rising from 100 to 600 , sharply increases when heated to 600700 and practically becomes absolute after preliminarily preheating to higher temperatures. Practical value. Research results will be useful in concepts of processes accompanying destruction of structured sands with water-soluble binders expanding, as well as in technologies and equipment development designed for SSS rods and mold rests removing from castings.

Validation of a thermo-hydro-mechanical model of freezing of water-saturated soil based on laboratory tests results

Frost heave of freezing water-saturated soils is an important worldwide problem from an engineering point of view. In cold regions, this phenomenon significantly affects foundations of buildings and road pavements. Application of artificial ground freezing to underground construction due to frost heave can cause an undesirable uplift of the ground surface and an increase in pressure acting on a lining and frozen wall. In the present paper, a mathematical model of soil freezing enabling one to predict soil deformation due to phase transformation of pore water into ice is proposed. The model is based on a set of nonlinear equations of water transfer, heat transfer, and equilibrium which are solved relative to porosity, temperature, and displacement variables. Constitutive relations of the poromechanics theory along with Bishop-type effective stress are used to simulate the mechanical behavior of soil during the process of pore water freezing and to evaluate pore pressure depending on a changein porosity and volumetric strain. Moreover, equations of the associated flow rule of plasticity are incorporated into the model to describe an inelastic volumetric expansion of the freezing soil induced by pore ice pressure. The ability of the model to capture essential features of the freezing process of water-saturated soils is demonstrated by numerical simulation of two laboratory tests. For the first test, a comparison between results of the numerical simulation and experimental measurements of variations of temperature and uplift of the top surface of silty clay specimens with time has been conducted. It has been shown that the numerical results are highly consistent with the measurements when the soil specimen is frozen with the growth of a massive cryogenic structure. In the numerical simulation of the second test, the calculated radial deformation of freezing soil is in good agreement with the experimental measurements, obtained by a fiber-optical sensor during the radial freezing of the quartz sand sample in a closed system.

Identifikasi Kandungan Unsur pada Pasir Kuarsa Menggunakan Metode X-Ray Flourescence di Kecamatan Samadua, Aceh Selatan

Quartz sand is a non-metallic natural resource that can be used to develop various kinds of human needs, however, it is necessary to know in advance the amount and elements contained therein. This research will conduct a study related to the amount of element concentration in quartz sand in Samadua District, South Aceh Regency. The research method used in this research is the X-Ray Fluorescence technique. The results showed that the elements found in the quartz sand samples were Si, K, Ca, Ti, V, Cr, Mn, Fe, Cu, Sr, Ba, and Eu. From these results, there are three elements that have the highest concentration, namely the element Si as much as 62%, Ca as much as 15.7%, and element K as much as 13.7%.

A mathematic model for the soil freezing characteristic curve: the roles of adsorption and capillarity

The relationship between the unfrozen water content in frozen soil and negative temperature is defined as the soil freezing characteristic curve (SFCC). The SFCC plays a crucial role in understanding the hydrothermal migration, frost heaving and constitutive relations of frozen soil. The mechanism of the SFCC is less understood, especially in the low-temperature range. Considering the adsorption and capillary action between soil particles and the ice interface, a new SFCC model for saturated frozen soil is proposed from the pore scale. The predicted results of the model show that the unfrozen water content gradually decreases with the increasing particle radius at the same temperature. The SFCC of monodisperse silica microspheres and quartz sand samples were tested based on nuclear magnetic resonance technology. The experimental results were compared with the mathematical model, which showed that the new SFCC model is in good agreement with the experimental results. The new model has a clear physical meaning and can provide a theoretical basis for understanding the phase change process in frozen soils, which is of great significance to the application of the proposed model.

The Study of the Quartz Sand Bio Consolidation Processes as a Result of Carbonate Mineralization by Urolithic Bacteria

The complexity and a large number of variable factors of the bacterial carbonate mineralization process in the cement stone system, which is a polylineal and polydisperse system, has led to the question of each component’s role in bio consolidation processes. For carbonate biomineralization occurring in cement concrete during its restoration, it is impossible to fully describe the bio consolidation mechanism without studying the effect on individual components of the cement system (aggregate and binder). In the environment of quartz sand (the most common type of aggregate in cement concrete) there is no direct source of calcium, which is found in cement stone, which excludes the influence of abiotic factors (alkalinity of the medium) on the calcium carbonate production by bacterial cultures. This article presents the results of the study of carbonate biomineralization by urolithic bacterial cultures in a filler medium, in which quartz sand of three fractions (1.25–0.63; 0.63–0.315; 0.315–0.16) was used to assess degree and intensity of induction processes. As a result of the study, the physical and chemical factors of the bacterial carbonate mineralization process intensification in quartz sand samples were established. The time boundaries of the appearance of a consolidated layer were revealed within two fractions (0.63–0.315 and 0.315–0.16), which are directly related to the penetration depth of the solution with precursors and the bacterial inoculum by the percolation method. The analysis of the cemented layers’ microstructure is carried out, the features of neoplasms are considered. The type of bacterial culture that exhibits the most active cementing properties - Bacillus pumilus (VKM B-23).

Activation of Diatomaceous Earth Low-Temperature Plasma

In residential and industrial buildings, a special air environment is formed, which contains gas shaped toxic chemical compounds. A significant part of such substances comes from finishing polymer containing materials. Virtually all polymeric materials release certain toxic chemical compounds into the air. The methods and methods of air cleaning are different. One of the ways to solve the problem associated with providing the required standards for the quality of indoor air is the development and use of new efficient building materials using aggregates that have a high sorption capacity. The paper presents the results of a study of the effect of low temperature non-equilibrium plasma on the sorption characteristics of aggregates based on diatomite earth. Studies have been conducted on samples of natural diatomite and quartz sand. When activated by low temperature nonequilibrium plasma, the structure changes, which leads to an increase in the sorption characteristics of the samples under study.

Determination of trace elements in high-purity quartz samples by ICP-OES and ICP-MS: A normal-pressure digestion pretreatment method for eliminating unfavorable substrate Si

The analysis of siliceous matrix samples may adopt a two-step pretreatment, which includes melting with ammonium hydrogen fluoride and redissolving with nitric acid. However, the residual of substrate silicon unfavorable to the determination of trace elements in the samples due to serious matrix effects. Here, a new digestion method using simultaneously both ammonium bifluoride and nitric acid under normal pressure was developed for high-purity quartz sand sample. The digestion pretreatment is a two step process: melting/dissolving with both ammonium bifluoride and nitric acid at 200 °C for 2 h, and evaporating the solution at 250 °C to dryness. As confirmed by XRD analysis, silicates in the sample were converted to (NH4)3SiF6NO3 in the melting/dissolving step. TGA analysis shows that the generated (NH4)3SiF6NO3 could be decomposed and evaporated completely at 250 °C, which ensured a complete removal of silicon by the followed evaporation of the solution at 250 °C. As a result, the followed ICP-OES and ICP-MS analysis needed a solution dilution of only 100 times for the determination of Ca, Mg, Al, Rb, Ba, REE and other trace elements. The new method was applied to the analysis of three certified reference materials, and the results were well consistent with the standard value with RSD% values between 0.62% and 9.73%. Therefore, this method can be applied to the analysis of trace elements in high purity silica-based samples, with the advantages of time-saving, small dilution factor (only 100 times) and low detection limit.

CSRR-Based Microwave Sensor for Dielectric Materials Characterization Applied to Soil Water Content Determination.

A new and compact sensor based on the complementary split-ring resonator (CSRR) structure is proposed to characterize the relative permittivity of various dielectric materials, enabling the determination of soil water content (SWC). The proposed sensor consists of a circular microstrip patch antenna supporting a 3D-printed small cylindrical container made out of Acrylonitrile-Butadiene-Styrene (ABS) filament. The principle of operation is based on the shifting of two of the antenna resonant frequencies caused by changing the relative permittivity of the material under test (MUT). Simulations are performed enabling the development of an empirical model of analysis. The sensitivity of the sensor is investigated and its effectiveness is analyzed by characterizing typical dielectric materials. The proposed sensor, which can be applied to characterize different types of dielectric materials, is used to determine the percentage of water contained in different soil types. Prototypes are fabricated and measured and the obtained results are compared with results from other research works, to validate the proposed sensor effectiveness. Moreover, the sensor was used to determine the percentage of water concentration in quartz sand and red clay samples.

Sample pretreatment for voltammetric determination of Pd - selective separation and preconcentration using Cellex-T

Constant increase of the content of platinum group elements in the environment creates the need for their analysis in natural samples. Especially determination of palladium is challenging: it occurs at ultra-trace levels, analytical techniques offer too high limits of detection and interferences from sample matrix limit the application of some analytical methods. The aim of this work was to propose a complete methodology of Pd determination, with special attention paid to establishing the conditions for efficient decomposition of thiourea. The analysis was performed using ICP MS and/or voltammetry in samples naturally containing traces of Pd. The procedure includes sample digestion in aqua regia, separation of Pd from a complex natural matrix simultaneously with its 10-fold preconcentration (SPE) on anion-exchanger Cellex-T (Pd elution with 0.10 mol L−1 TU in 0.10 mol L−1 HCl). Voltammetric determination of Pd is possible after mineralization of thiourea in conc. nitric acid or the mixture of nitric and perchloric acids. The recovery is very satisfying, reaching more than 90%. The proposed methodology can be applied for quartz sand samples containing at least 2 ppb Pd.