Crushed Samples Research Articles

Image processing and neural network technique for size characterization of gravel particles

Particle size is considered one of the significant characteristics used in geotechnical practices. Traditionally, sieve analysis is utilized for coarse-grained soil. However, this method could be time consuming and take much effort, especially for large scale infrastructure projects. This paper presents an efficient method for estimating gravel particle characterization utilizing image processing and artificial neural network technique (IPNN). The proposed algorithm is performed by utilizing particle boundary delineation and shape feature extraction to train a neural network model for estimating gravel size distribution curve. It is found that excellent agreement exists between the results obtained from conventional sieve analysis and neural analysis for gravel soil particles with maximum difference in passing percentages up to only 3.70%. The proposed technique shows satisfactory results for crushed stone samples with maximum difference in passing percentages about 10.90% mainly in large diameter particles. The presented technique (IPNN) could offer a promising alternative technique for material quality control process especially in large scale projects.

An experimental investigation into crashworthiness of filament wound intra-yarn hybrid glass/jute epoxy composites tubes under quasi-static axial and lateral compression

The increasing demand for sustainable materials in the automotive industry has driven the research towards exploration of natural fiber composites for crash structures. This study investigates the quasi-static axial and lateral crushing behavior of hybrid glass/jute fiber epoxy tubes. Intra-yarn hybrid mixing ratios of jute and glass fibers were tested to evaluate the feasibility of using natural fibers as eco-friendly alternatives to traditional synthetic composites. A total of five different configurations were fabricated using filament winding process. The experimental results were analyzed for collapsing behavior, failure modes, and energy absorption characteristics. The hybrid epoxy tubes revealed fiber-matrix fracturing, local buckling, and delamination as three primary failure modes under crushing tests. The hybrid configuration with 25 % jute fiber and 75 % glass fiber demonstrated optimal crashworthiness performance, achieving the highest specific energy absorption (SEA) values of 15.85 J/g under axial loading and 2.96 J/g under lateral loading. The configurations with higher jute content of 50 % and 75 %, showed decreasing SEA and crush force efficiency (CFE) values, with brittle fracturing and delamination as dominant failure modes, indicating a trade-off between weight and energy absorption efficiency. The neat glass fiber configuration maintained nearly consistent CFE values of 0.55 and 0.56, between axial and lateral loadings respectively, demonstrating isotropic behavior in energy absorption. Conversely, the neat jute fiber configuration improved SEA to 12.14 J/g under axial loading but exhibited significant limitations under lateral loading, with SEA decreasing to 0.69 J/g. Visual examination of crushed samples highlighted local buckling in GF configurations and brittle fracturing in hybrid and neat jute fiber configurations. The scanning electron microscope (SEM) analysis provided detailed insights into the microstructural characteristics and failure mechanisms, highlighting the inter-laminar debonding between the jute and glass fibers in hybrid configuration. By evaluating the combined effects of hybridization and loading conditions, the present study contributes to developing eco-friendly and efficient materials for automotive safety, aligning with industry sustainability goals.

Physico-mechanical properties of halite and gypsum–mudstone crushed rock backfills of the Mercia Mudstone Group

Permanent disposal of radioactive waste in deep geological repositories (DGRs) relies on engineered barriers, such as crushed rock backfills, to ensure that wastes are isolated and contained. The performance of crushed rock backfill, during construction, operation and closure, relies on optimizing its mechanical properties. This paper explores how density and composition influence the strength of (i) crushed halite and (ii) crushed gypsum–mudstone mixtures of the Triassic Mercia Mudstone Group, which is a potential DGR host rock in the UK. Unconfined compressive strength (UCS) testing of compacted halite demonstrated that strength correlated with compaction density, with UCS increasing from 220 kPa at a density of 1.72 g cm −3 up to 6600 kPa at the maximum achieved density of 1.83 g cm −3 . Direct shear testing revealed an angle of internal friction for crushed halite samples of 39°–40° at a density of 1.5 g cm −3 . Direct shear testing of gypsum–mudstone composites from 100% gypsum to 100% mudstone revealed that higher gypsum percentages provide greater frictional shearing resistance, whilst higher mudstone percentages promote more cohesive strength. Data are also presented on bulk materials characterization by X-ray fluorescence (XRF), scanning electron microscopy with energy-dispersive spectrometry (SEM-EDS) and optical microscopy. This research provides insights into how the strength properties of compacted crushed halite and gypsiferous mudstone backfills can be engineered through control of density and composition.

Morphostructural, Chemical and Genetic Features of Native Gold in Brown Coals from the Yerkovetsky Deposit, Far East Russia

We studied the morphostructural features and chemical composition of micron and submicron particles of native gold from brown coals and overcoal sediments of the Yerkovetsky deposit (Zeya-Bureya sedimentary basin, Far East Russia). The samples of coal and host rocks in the form of thin sections, as well as coal particles and grains of native gold obtained during the process of dispersion and the fractionation of loose and crushed samples divided according to size and density, were analyzed using scanning electron microscopy in combination with X-ray microanalysis, involving various visualization modes. It was revealed that native gold is syngenetic with the mineralization of brown coals, and microphases dispersed in the minerals of overcoal loose and sandy-clay sediments were the source of native gold. In coal, gold is accumulated at the stages of formation (alluvial and eolian, including terrigenous and ionogenic subtypes) and the diagenesis of coal deposits (ground-infiltration subtype). A significant part of the mineralization process of coals and the formation of microparticles of native gold was contributed to by the descending water infiltration of polycomponent colloid solutions. During the dehydration of hydroxysiliconized iron-based hydrogels, mineral phases have an unstable composition and floccular structure and contain submicron gold particles. The coatings of all gold microparticles have identical origin and composition. Coal beds that border host rocks are an open system with a constant inflow of the substance, which leads to the gradual formation of polycomponent aggregated particles in micro cavities. Part of the gold in coals occurs as sulfur-bearing complexes dissolved in pore water. The key factor in the migration and deposition of gold in coals is the inorganic substances involved in the processes of coal mineralization. Organic substances play a more passive role and have medium-forming, fractionating (colloid, molecular, and ionic sieves), and accumulation functions.

Study of the Internal Rebreaking Characteristics of Crushed Gangue in Mine Goaf during Compression

The deformation and re-crushing characteristics of different lithological caving crushed gangues in mine goaf directly affect the overburden strata movement, which significantly affects the surface subsidence of mining goaf. The effect of particle size on the re-crushing characteristics of different lithological caving crushed gangues in mine goaf is investigated in this study based on an innovative compression–AE (acoustic emission) measuring method. The results showed the following: (1) The compression deformation was divided into three stages: rapid, slow, and stable compaction. With the increase in axial pressure, the large particle skeletons were destroyed, medium particles were displaced and slid, and small particles filled the pores. (2) For singular lithologies, stress was positively correlated with pressure, and porosity was negatively correlated with stress. The composite sample was between the singular gangue samples. (3) The fractal dimension of crushed gangue samples was exponentially related to the proportion of gangue in singular and combined lithologies. (4) The cumulative AE count and energy of the combined lithological gangue samples were between those of the singular samples. The research results provide a theoretical foundation for further research into the characteristics of the overlying strata, surface movement, and safety management of the goaf.

Influence of Cold Work on the Efficiency of Vibratory Machining

The aim of the article was to determine the impact of crushed condition (work hardening) on the effectiveness of the vibratory machining. The vibratory machining processing was carried out in two steps. The first step consisted of mechanical abrasion and remove oxides from the surface of the workpieces with abrasive media. While in the second step, smoothing - polishing with metal media was performed. Vibratory polishing also strengthened the treated surfaces. The test results were compared for samples in the crushed state (work hardening, plastic processing) and samples subjected to recrystallization annealing heat treatment. Mass losses, changes in the geometric structure of the surface and changes in the hardness of the machining surfaces were analyzed. Samples subjected to recrystallization, as compared to the samples in the state after work hardening-plastic working, are characterized by a slightly higher arithmetic mean surface roughness and lower surface hardness than for analogous processes for samples not subjected to heat treatment. Heat treatment of annealing allows to remove the effects of crushing and thus it is possible to obtain larger mass losses. Smaller burrs dimensions were obtained for samples after the heat treatment – annealing than after work hardening.

Palynofacies analysis and depositional environment of the upper Triassic Kurra Chine Formation: integrated by samples from sarta and Tawke oil fields and outcrop samples from sirwan valley in the kurdistan region, northern Iraq

Palynofacies (PF) analysis was conducted on 34 crushed samples of the Upper Triassic Kurra Chine Formation. These samples were collected from one outcrop sample and two production wells in northern Iraq. A 10μm nylon mesh sieve was used for the concentration of palynomorphs. Four palynofacies types were found in this study. PF1 was characterized primarily by amorphous organic matter (AOM), suggesting a distal suboxic-anoxic depositional environment. PF2 comprised of AOM, along with some Phytoclasts and palynomorphs, indicating a distal dysoxic-oxic shelf depositional environment. PF3 displayed an increasing volume of palynomorphs, signifying a distal dysoxic-anoxic shelf depositional environment. PF4 predominantly consisted of palynomorphs and Phytoclasts, representing a mud-dominated oxic shelf (distal shelf) depositional environment. Kerogen types were identified as type II, which is oil-prone in three palynofacies, and type III which is gas-prone in one palynofacies.

Non-Destructive Analysis Using Near-Infrared Spectroscopy to Predict Albumin, Globulin, Glutelin, and Total Protein Content in Sunflower Seeds

This pilot study explores the potential of near-infrared spectroscopy (NIRS) for predicting sunflower seed protein content, focusing on both crushed and husked samples to address agricultural sustainability concerns. Sunflower seeds are renowned for their richness in both oil and protein content. The important role of sunflower seeds in the food and feed industries underscores the importance of using precise analytical tools to determine their composition. In essence, the nature of the hull of sunflower seeds, which skews the interaction between the seed and light, necessitates a sophisticated analysis. This study analyzes 326 samples using a near-infrared spectrometer to develop robust partial least squares (PLS) models. High accuracy is achieved in predicting total protein for crushed samples (r²c = 0.97, RMSEC 0.54%, RPDc 6; r²p = 0.78, RMSEP 1.24%, RPDp 2.1). Extending the scope to husked samples, promising results emerge for crude protein prediction (r²c = 0.93, RMSEC 0.86%, RPDc 3.9; r²cv = 0.83, RMSECV 1.39%, RPDcv 2.4). Additionally, this study delves into protein fractions (globulin, albumin, and glutelin) in crushed seeds, adding depth to the analysis. In conclusion, NIR spectroscopy proves valuable for rapid prescreening in breeding, especially when working with hulled grains, offering non-destructive efficiency and predictive accuracy in agricultural analysis. The novel exploration of protein fractions in sunflower seeds further enhances this study’s importance, providing a valuable contribution to the field and underscoring the practical applications of NIR spectroscopy in sustainable agriculture. In conclusion, the opacity of sunflower seed hulls poses challenges in infrared spectroscopy, limiting light penetration and accuracy. Dehulled seeds are preferred for reliable results, overcoming hull-related limitations. Although grinding provides the advantages of uniformity and reproducibility for near-infrared (NIR) spectroscopy, the preference for dehulled grains persists. The practical need for accurate analysis in agriculture and breeding drives the choice of spectroscopy on dehulled seeds, allowing for replanting.

A DEM-CFD Approach for Predicting Pressure Drop Through Packed Bed of Crushed Rocks

Predicting the pressure drop over a packed bed of air-crushed rocks is a crucial parameter for a solar storage system to be economically viable. The selection of the blower and the estimation of the total capacity of the storage system are highly dependent on it. There are various parameters that influence the air flow through the bed, such as the shapes and sizes of the crushed rocks, which affect the packing density and particle arrangement. In this paper, the crushed rock was represented by an ellipsoidal shape with the same volume and aspect ratio as the average of randomly collected crushed rock samples to investigate the pressure drop through the packed bed. Simulation models were developed to assist in driving a pressure drop correlation as well as the effect of particles' orientation on pressure drop. For simulation, a Discrete Element Model (DEM) was used to generate the particles and Computational Fluid Dynamics (CFD) to simulate the flow over the particles. To validate the DEM/CFD models, experiments consisting of a packed bed of ellipsoidal particles and crushed rocks were developed. Consequently, an equation based on the porous media approach was proposed to predict the pressure drop, and the correlation was found to underestimate the pressure drop through the crushed rock by less than 20% in the horizontal flow.

Spent Foundry Sand (SFS)-Gum Arabic Admixed Concrete: X-Ray Diffraction, Microstructure, Acid and Sulphate Analysis

Concrete sustainability studies have opened opportunities in the use, and understanding of the characteristics, and performances of supplementary cementing materials (SCMs) using modern methods of investigation. The effect of spent foundry sand (SFS) with replacement levels of 10 and 20 % by wt. % of the fine aggregate (FA), 0.5 % dosage of gum Arabic (GA) on concrete, and its performance in acid and sulfate medium are presented. The investigations are carried out using crushed compressive strength test samples, prepared using a mix of 1: 3: 5, and cured for 28 days in water. The XRD analysis studied the crystalline and mineral phases of the concrete, the SEM-EDS analysis, the morphology (texture) and structural characteristics of the concrete samples, while the Acid and Sulphate analysis to understand the effects of these media on SFS-GA concrete. The results show that SFS and GA have acceptable characteristics for quality concrete. The XRD and SEM results show marked transformations in the crystalline and mineral phases, the morphology and structural characteristics of the hydration products of the concrete samples, because of the addition of GA and SFS, respectively. The performances of the concrete samples with GA and SFS, in the HNO3 medium show better performances than in the H2SO4 medium and better performances in Na2SO4 than in the MgSO4 medium with acceptable characteristics for quality concrete. The XRD and SEM results show marked transformations in the crystalline and mineral phases, the morphology and structural characteristics of the hydration products of the concrete samples, because of the addition of GA and SFS, respectively. The performances of the concrete samples with GA and SFS, in the HNO3 medium, show better performances than in the H2SO4 medium and better performances in Na2SO4 than in the MgSO4 medium

Comparative Study of the Rosin-Rammler and Gates-Gaudin-Schuhmann Particle Size Distribution Models for Microwave-Assisted Crushing Analysis

Microwaves selectively heat dielectric minerals within the ore particles during a relatively brief exposure period, inducing thermal stresses that generate cracks, thereby diminishing the structural integrity of the ore particles. The immediate effect of employing this technique is an alteration in the particle size distribution (PSD) of the comminution product. In this research, two types of diamond-bearing kimberlite ore underwent microwave irradiation before the crushing process. The microwave experimentation was carried out utilizing a multi-variable power system with a maximum capacity of 15 kW, within a single-mode cavity structure. The exposure time was adjustable to vary the input microwave energy, which ranged from 6 kJ to 270 kJ. Three distinct narrow feed size classes were examined: -31.5 +16 mm, -16 +6.7 mm, and -31.5 +6.7 mm. Each sample weighed five hundred grams. Both the microwave-treated samples and the untreated samples (as-received) were subjected to crushing using a single-roll crusher. The PSD of the crushed product was determined through a standard sieving test and subsequently analyzed using empirical PSD models. These models are advantageous for enhancing the accuracy of PSD analysis by linearizing datasets that often exhibit skewness towards the distribution's tail end. Two widely recognized empirical PSD models, the Rosin-Rammler (RR) and Gates-Gaudin-Schuhmann (GGS) models, were employed to assess how microwave pre-treatment influences the PSD of the crushed product. Various comparative parameters derived from these models, such as the P50, distribution uniformity (DP), and critical fine sizes, were evaluated for both untreated crushed samples and the samples treated with microwaves. The findings indicated that crushed products treated with microwaves generally displayed improved alignment with both PSD models in comparison to the untreated samples. Notably, the GGS model exhibited marginally higher overall r-squared values compared to the RR model. Moreover, the microwave-treated samples showcased a slightly coarser and more uniform PSD when contrasted with the untreated counterparts. Among the various microwave energy inputs tested, the lowest input at the highest power level yielded the most substantial increments in P50 and DP. Simultaneously, it led to the most significant reduction in fractions corresponding to critical fine sizes.

ТИПОМОРФНЫЕ ПРИЗНАКИ САМОРОДНОГО ЗОЛОТА РОССЫПИ РЧ. ЛЕВЫЙ УЛАХАН ХАПТАСЫННААХ И ЕГО ВЕРОЯТНЫЕ КОРЕННЫЕ ИСТОЧНИКИ (АНАБАРСКИЙ ЩИТ)

The paper deals with studied typomorphic features of placer gold of the Left Ulakhan Haptasynnakh River, drainage rocks of the central Billakhskaya tectonofluid zone of the Anabar Shield, aimed at identifying its indicator signs and probable indigenous sources. The predominance of poorly rounded, mainly angular-cloddy individuals with rough pitted-lumpy surface, often with coatings of variable aluminosilicate composition, with small accretions of quartz and potassium feldspar, as well as a fraction >0.5 mm to 40% allowed the studied gold to be attributed to the autochthonous type. The study of nearby sulphidized rocks of the Haptasynnaakh zone showed that an ore mineralization is represented by a variety of mineral forms. The main ore mineral is pyrite. A wide range of telluride minerals was identified with predominance of silver and bismuth tellurides. For the first time, medium-high-grade gold of lamellar and rod-shaped forms was distinguished from crushed samples of mineralized rocks. Comparative analysis of the mineral inclusions composition in poorly rounded placer gold with a wide variation in gold fineness of the Left Ulakhan Haptasynnaakh and mineral parageneses of ores of the Haptasynnaakh ore zone allows researchers to assert that the zone ore manifestations are indigenous sources of the studied gold. The discovery of gold with an ore appearance of fraction >0.5 mm in the placer suggests the presence of mineralization of its coarser fractions in relatively deep horizons. This fact determines positive prospects for further study of the territory.

Glass-Containing Matrices Based on Borosilicate Glasses for the Immobilization of Radioactive Wastes

Glass-containing materials are widely considered among the most reliable materials for the immobilization of radioactive waste materials. The present work considers the synthesis of glass–ceramic and glass crystalline composite materials based on borosilicate glasses. The synthesis of glass–ceramic materials was carried out by a gradual temperature decrease, followed by crystallization for several hours. Sintering of crushed samples with crystalline components was carried out as an alternative procedure. Porous glasses were produced from glass melts by quenching. After impregnating the resulting porous materials with aqueous solutions of cesium nitrate, compaction of the glass was carried out to form glass crystalline composites. The thermochemical characteristics of the parent glasses were determined using the differential scanning calorimetry method. The phase composition and structure of the glass-containing materials were determined using X-ray phase analysis, X-ray spectral microanalysis, and Raman spectroscopy.

Rapid Detection of Total Viable Count in Intact Beef Dishes Based on NIR Hyperspectral Hybrid Model

The total viable count (TVC) of bacteria is an important index to evaluate the freshness and safety of dishes. To improve the accuracy and robustness of spectroscopic detection of total viable bacteria count in a complex system, a new method based on a near-infrared (NIR) hyperspectral hybrid model and Support Vector Machine (SVM) algorithms was developed to directly determine the total viable count in intact beef dish samples in this study. Diffuse reflectance data of intact and crushed samples were tested by NIR hyperspectral and processed using Multiplicative Scattering Correction (MSC) and Competitive Adaptive Reweighted Sampling (CARS). Kennard–Stone (KS) and Samples Set Partitioning Based on Joint X-Y Distance (SPXY) algorithms were used to select the optimal number of standard samples transferred by the model combined with root mean square error. The crushed samples were transferred into the complete samples prediction model through the Direct Standardization (DS) algorithm. The spectral hybrid model of crushed samples and full samples was established. The results showed that the Determination Coefficient of Calibration (RP2) value of the total samples prediction set increased from 0.5088 to 0.8068, and the value of the Root Mean Square Error of Prediction (RMSEP) decreased from 0.2454 to 0.1691 log10 CFU/g. After establishing the hybrid model, the RMSEP value decreased by 9.23% more than before, and the values of Relative Percent Deviation (RPD) and Reaction Error Relation (RER) increased by 12.12% and 10.09, respectively. The results of this study showed that TVC instewed beef samples can be non-destructively determined based on the DS model transfer method combined with the hybrid model strategy. This study provided a reference for solving the problem of poor accuracy and reliability of prediction models in heterogeneous samples.

Tuning of Morphology and Surface Properties of Porous Silicones by Chemical Modification

The behavior of materials against water is a key element in many practical applications. Silicones are hydrophobic by nature and can be chemically modified to become hydrophilic or highly hydrophobic, while combining intrinsic surface properties with morphological details may lead to superhydrophobic materials. Chemically modified porous silicones and their surface properties have rarely been investigated. Our aim in this study was to tune the surface properties of porous silicone materials by a combination of chemical modification and emulsion templating The porous silicones were obtained by two cross-linking reactions in toluene–water emulsion, in mild conditions: dehydrocoupling of poly(methylhydrogen)siloxane (PMHS) and dimethyl-methylhydrogensiloxane copolymers and UV-initiated thiol-ene addition on a poly(dimethyl-methylvinyl)siloxane, respectively. Apart from the pores generated by water droplets, in the first process, additional large pores appeared due to hydrogen evolution. Their size and number diminished along with the cross-linking degree; thus, the porosity was tuned by adjusting the composition of the reaction mixture. Chemical modifications were performed in situ to introduce more hydrophobic groups (hexane and trimethylsilane) or hydrophilic groups (thioethanol), modifications that were followed by FT-IR spectroscopy. The inner morphology and powder wetting behavior of the crushed samples were investigated by SEM, tensiometry analyses, and contact angle measurements. The materials showed morphological particularities and surface properties that spanned from hydrophilic to superhydrophobic with lotus or petal effects.

A combined DFT and NPD approach to determine the structure and composition of the ε-phase of tungsten boride

The ε-phase of tungsten boride, conventionally labelled as W2B5, has been identified as a promising candidate for shielding application in spherical tokamak fusion reactors. However, further research has been hindered by a lack of agreement on the structure and even composition of the ε-phase. Here, we identify the stable crystal structure and stoichiometry range of ε tungsten borides through a combination of ab initio simulations and neutron diffraction of isotopically enriched samples. We considered the ability to accommodate hypo-stoichiometry in six published structures of the ε phase. Chemical disorder was modelled using configurational ensembles to account for entropy of non-stoichiometry. We show that two W2B4-x structures (with x=∼0.25 − 0.5), with space group symmetry P63/mmc and P63/mcm, appear to be thermodynamically stable. These candidate compounds have 6.2 − 7.8 at.% less B than the W2B5 composition reported in exiting phase diagrams. We confirm these findings by means of neutron powder diffraction, performed on 11B-enriched arc-melted and crushed samples. Rietveld refinement using the neutron data shows the ε-phase to be better described as W2B3.60(2) (P63/mcm), in keeping with density functional theory (DFT) calculations. Linear change in DFT-derived lattice parameters of the candidates for the ε-phase proposes a simple model to assess the tungsten boride composition by measuring the lattice parameter (e.g. by X-ray diffraction. The simulations also reveal that the material can accommodate a range of stoichiometric variations (via B vacancies) with relatively small stored energy, which is a desirable feature for neutron shielding application.

Neoarchean synkinematic metamorphic peak in the Isua supracrustal belt (West Greenland)

Abstract We present petrological data and seven Lu-Hf garnet–amphibole–whole rock ages obtained from a single garnet-hornblende-mica schist sample from the Isua supracrustal belt (West Greenland). Garnets grew during prograde metamorphism toward regional amphibolite-facies peak conditions, and a mylonitic foliation formed during and after garnet growth. Garnet crystals show typical prograde zoning with no visible traces of a relict garnet generation. They do show various degrees of retrogression. While some crystals are perfectly euhedral with only minor chemical alteration along cracks, others are elongated in the foliation and either grew in this shape or were deformed. Six garnet splits were separated from crushed single crystals and one from a crushed bulk sample. Individual three-point garnet–hornblende–whole rock ages scatter between 2.603 ± 0.018 Ga and 2.432 ± 0.059 Ga for single garnets. The garnet split from the bulk sample defines an age of 2.463 ± 0.031 Ga, the data point farthest from the regression line for all data points (2.551 ± 0.074 Ga, mean square of weighted deviates = 25). We interpret these data to indicate partial retrogression of a Neoarchean garnet population not significantly older than the oldest obtained three-point age. Well-preserved garnet zoning, regional peak temperatures well below the closing temperature of the Lu-Hf system, and the small scatter of Lu-Hf ages preclude an interpretation of the observed metamorphism and deformation as being Eoarchean in age.

An optimization method for equivalent bulk permeability of gas shale matrix with crushed samples and re-recognition of the influence of pressure and particle size

The pressure decay (or gas expansion) test with crushed samples has been used to evaluate the matrix permeability of shale and other low-permeability rock for many years. However, there still exist uncertainties relating to particle size and equilibrium pressure. The existing late-stage curve fitting method has the advantage of easy calculation, but the assumption that gas enters particles with a single permeability value is not generally applicable for shale samples, and late-stage analysis may lead to underestimation. This study proposes an optimization method to determine the equivalent bulk permeability that ensures the smallest sum of squares of errors between the forward-predicted pressure decay curve and the measure one. Both the optimization and curve fitting method are applied to two shale samples from the Ordovician Wufeng Formation of two wells in the Sichuan Basin, China with improved apparatus and testing procedures. The optimization method is superior to the curve fitting method in the repeatability and regularity on the change of apparent permeability with pressure. A strong linear relationship between apparent permeability and coefficient of compressibility is established between 3 and 12 bars. The variation of permeability with particle size is more diverse than that is commonly understood and might be nonmonotonic, depending on the change of pore structure during crushing. Change of apparent permeability with pressure (non-Darcy feature) is proposed as a criterion of whether pore structure has changed significantly. It is suggested to measure the variation of permeability with pressure and particle size to obtain a more comprehensive understanding of matrix permeability and pore structure.

Integrated approach for closure correction of mercury injection capillary pressure measurements

Closure correction is a key requirement for a reliable petrophysical evaluation using mercury injection capillary pressure (MICP). The available correction methods rely on identifying deflection points on capillary pressure curves which is often difficult and subjective and requires additional information for macropores that control the closure effect. The proposed approach in this study is novel in terms of integrating the pore-throat size distribution and incremental mercury intrusion data from MICP with porosity from routine core analysis as well as 2D visualization and watershed segmentation from thin section images. The proposed approach allows for lowering the uncertainty in closure correction by incorporating the pore-throat sizes and segmented porosity of the macropores from thin-section images. We tested this approach on samples of the Austin Chalk and Indiana Limestone. The effects of sample size and equilibrium time were also investigated. Identifying the closure pressure is demonstrated to be more difficult on small crushed samples due to the impact of mercury conformance associated with the increased specific surface area. The impact of increasing the equilibrium time is insignificant on relatively permeable Austin Chalk. However, for the tighter Indiana Limestone, conducting fast MICP experiments results in inconsistent and misleading results. We used rate-equilibrium testing at 0.001 μL/g to generate initial-residual curves and evaluate pores accessibility. We show that Austin Chalk pores are fully intruded below 10,000 psia whereas Indiana Limestone requires higher pressure to invade all the pore systems. This study emphasizes the importance of integrating additional information with the MICP data for the closure correction of complex pore systems.

Strength and deformation characteristics of slag crushed stone of coal thermal power plants

Mechanical properties of the slag crushed stone (coarse-grained ASM), formed in the course of coal combustion at Kansk-Achinsk, Kuznetsk coal deposits (in boilers equipped with liquid and dry slag removal facilities) and the application of the slag crushed stone in roadbuilding are considered. In the course of the research, the crushability and the deformation modulus of particular fractions of slag crushed stone samples taken from the dumps of Novosibirsk TPP-3 (that consumes the coal of the Kansk-Achinsk coal mining field) and from Novosibirsk TPP-2 and Seversk TPP (that consume the coal of the Kuznetsk coal mining field) were identified. To assess the factors influencing the mechanical strength of the slag crushed stone, ignition losses, the content of flaky and acicular particles, dust and clay particles and clay lumps was made. The difference in the mechanical strength of samples having different genesis was identified. The graphs obtained in the course of testing were assessed and deformability characteristics were calculated (for materials having different fineness values). The factors influencing the mechanical strength of slag crushed stone were determined. Dependencies between deformation parameters and crushability of the slag crushed stone were obtained. Some mechanical and physical parameters of the slag crushed stone were identified; they were applied to outline potential areas of the slag crushed stone application in road building. The mathematical relationship needed to project the deformation modulus of the slag crushed stone was identified. This relationship will be used to design structures to be made of this material.