Crushed Samples Research Articles

Laterite Sampling Preparation for Gold Exploration Survey at Western Burkina Faso, Northern Extension of the Lawra Belt

Laterite samples were divided into three and each sample was prepared differently for Au analysis using FA-AAS. The sample-type was identified based on the preparation end-material. The laterite sub sample types were field sample-sieved, field sample crushed and raw field sample-unprocessed. The Au analysis on these sub-samples showed 67% of the field sieved samples from the entire laterite samples had significant Au assays, 25% for the crushed field samples, 8% of both sieved and crushed samples had equal Au geochemical levels from KSG 009 samples. The raw field samples unprocessed returned insignificant Au assays. The study found field sieved samples of < 125 um size fraction to be the best sample preparation method for laterite samples and conclude that it should be employed to detect concealed Au mineralization in laterite capping terrains in the savannah regions.

Existing approaches to tight rock laboratory petrophysics: a critical review

A review of the existing methods for tight rock porosity, saturation, and permeability determination was performed taking into account that these methods should be applicable for Bazhenov formation evaluation. The following methods were considered: Archimedes mercury immersion; mercury displacement; caliper; helium pycnometry on crushed samples; nuclear magnetic resonance; modified retort method; modified Dean-Stark extraction; pulse decay method; and pressure decay test on crushed samples. The applicability of the pressure decay test on a crushed sample for Bazhenov formation evaluation is checked experimentally with the SMP-200 commercial permeameter. All the above listed methods were combined into five protocols for tight rock petrophysical evaluation. These protocols were analyzed and compared according to the following criteria: accuracy of the results; usage experience; time of measurements; easiness of interpretation; reliability and safety; price. The obtained results revealed that the most effective protocol is the one that includes pressure pulse on a core plug for permeability determination, He pycnometry and modified retort analysis on crushed samples for porosity and saturation determination. As there were cases when the proposed protocol was less effective vs. other protocols, a special scheme was suggested in order to choose the most effective protocol for tight rock petrophysical properties evaluation in definite conditions.

Specific Detection of Klebsiella variicola and K. oxytoca by Loop-Mediated Isothermal Amplification

Klebsiella spp. are opportunistic pathogens with clinical, veterinary and plant-associated isolates. A previous study showed that bacterial ooze from wetwood of severely declined ironwood trees in Guam contained Ralstonia solanacearum, Klebsiella variicola and K. oxytoca. In this study, Loop-Mediated Isothermal Amplification (LAMP) detected K. variicola and K. oxytoca specifically, using unique primer sets designed individually for each organism. Each LAMP detected its target specifically, while showing negative results for non-target bacteria and negative controls. LAMP detected Klebsiella in inoculated-ironwood stem tissues and bacterial ooze. Due to the presence of plant inhibitors, different sampling protocols were tested. Soaking plant tissue samples to allow diffusion of bacteria into solution, followed by boiling, provided optimum detection of Klebsiella directly from plant samples. False negatives obtained when using crushed plant samples were eliminated by including an enrichment step, involving plating and 12-h incubation. DGGE (denaturing gradient gel electrophoresis) and a colony-blot immunoassay using a Klebsiella-specific antibody also detected Klebsiella in inoculated ironwood. DGGE bands and antibody crossreactions from closely related enterobacters showed the potential for false positive results. The nature of LAMP makes it ideal for point-of-care testing, and when combined with the specificity of the LAMP primers developed in this study, demonstrates its potential as a routine field test for Klebsiella in ironwood in Guam, as well as clinical and veterinary diagnosis of Klebsiella infection. Additionally, the regions targeted for detection in this study have application across all forms of molecular-based diagnostics.

Economic Optimization of Horizontal-Well Completions in Unconventional Reservoirs

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 168612, ’Economic Optimization of Horizontal-Well Completions in Unconventional Reservoirs,’ by R.D. Barree, SPE, Barree &amp; Associates; S.A. Cox, SPE, PetroEdge Energy III; J.L. Miskimins, SPE, and J.V. Gilbert, SPE, Barree &amp; Associates; and M.W. Conway, SPE, Core Laboratories, prepared for the 2014 SPE Hydraulic Fracturing Technology Conference, The Woodlands, Texas, USA, 4-6 February. The paper has not been peer reviewed. This paper presents methods for production forecasting that give reasonable post-treatment predictions that have been found to be useful for economic planning. The proposed methodology provides an economically viable plan for optimizing lateral length, fracture spacing, and treatment design. The methodology focuses on the post-simulation effective reservoir volume. Results show that increasing apparent fracture length rarely affects long-term recovery. Likewise, adding more fractures within the same reservoir volume may increase early-time production rate and decline rate without contacting more reservoir volume or adding to long-term recovery. Introduction Industrywide, there appear to be several basic assumptions that govern expectations about recovery generated through horizontal-well stimulation in unconventional reservoirs. Depending on the basic belief system applied, dramatically different, even diametrically opposed, recommendations result. The first belief is that core-derived permeability values, usually from crushed samples, represent overall reservoir flow capacity accurately. This assumption frequently controls post-treatment expectations regarding treatment size, spacing of perforation clusters (fracture-initiation points), or number of treatment stages and most significant aspects of completion design. However, core permeabilities do not represent the overall reservoir flow capacities, something that diagnostic fracture injection tests (DFITs) or production analysis does achieve by measuring the integrated-system permeability, including any secondary fracture enhancement, including existing natural fractures and shear and extensional fracture enhancement developed during the stimulation process. The assumption that crushed-core-derived matrix permeability describes the system flow capacity is generally accompanied by the industry’s second belief, that created or seismically imaged fracture length represents the effective flowing length of the hydraulic fractures. The combination of these two beliefs is used by the industry to explain the observed production behavior in many models. In other words, belief in one requires belief in the other. However, field observations and many years of laboratory work strongly support the conclusion that effective fracture length is much smaller than the created or imaged length and that fracture cleanup is driven by the reservoir flow capacity. In very-low-permeability and low-pressure systems, the effective fracture length is limited by cleanup (flowing length) rather than by conductivity.

On the Potential of Tomographic Methods when Applied to Compacted Crushed Rock Salt

Compacted crushed rock salt is considered as potential backfill material in repositories for nuclear waste. To evaluate the sealing properties of this material knowledge concerning the nature of the pore space is of eminent interest. Here, the pore microstructures of crushed rock salt samples with different compaction states were investigated by X-ray (XCT) computed tomography and Focused Ion Beam nanotomography (FIB-nt). Based on these methods the pore microstructures were reconstructed and quantitatively analyzed with respect to porosity, connectivity and percolation properties. Regarding pores with radii $$> 4\,\upmu \hbox {m}$$ , porosity differs substantially in the two analyzed samples ( $$\phi = 0.01$$ and 0.10). The pore microstructures are considered isotropic in connectivity and percolation threshold. Using two finite-scaling schemes we found percolation thresholds with critical porosities $$\phi _{c} > 0.05$$ . Based on statistical considerations, the millimeter size samples that can be analyzed by XCT are large enough to provide a meaningful picture of the pore geometry related to macroporosity. The samples contain also a small fraction (i.e. $$< 0.01$$ ) of pores with radii $$< 1\,\upmu \hbox {m}$$ , which were resolved by FIB-nt. Often these pores can be found along grain boundaries. These pores are granular shaped and are not connected to each other. Typical samples size that can be analyzed by FIB-nt is on the order of tens of microns, which turned out to be too small to provide representative geometric information unless an effort is made that involves several FIB-nt realizations per sample.

Advances in Understanding Wettability of Gas Shales

Recent experiments show the strong water uptake of gas shales which are strongly oil-wet based on contact angle measurements.1,2 Clay hydration, microfracture induction, lamination, and osmotic effect are collectively responsible for the excess water uptake. However, the previous measurements are not sufficient to isolate the above factors nor to explain why the bulk of shale samples can hardly imbibe the oil which completely spreads on their surface. To answer the remaining questions, we measure and compare spontaneous imbibition of oil and water into the crushed packs of the similar shales. In contrast to the intact samples, the crushed samples consistently imbibe more oil than water. The comparative study suggests that the connected pore network of the intact samples is water wet while the majority of rock including poorly connected pores is oil-wet. This argument is backed by complete spreading of oil on fresh surfaces of the rock. In contrast to the artificial pores of crushed rock, the existing pore...

Investigation on pre-weakening and crushing of phosphate ore using high voltage electric pulses

Mechanical size reduction processes in the mineral processing industry are energy intensive. In this study, a novel High Voltage Electric Pulses Crusher (HVEPC) was designed and developed to pre-weaken and crush a phosphate ore. To compare the effectiveness of the new HVEPC in crushing with the conventional crushers, several rock samples of a phosphate ore were used and the effect of the capacitor, the voltage level and voltage rise time on the phosphate ore breakage was investigated. Comparing the particle size distribution of the crushed samples using both the HVEPC and the conventional crushers revealed the difference between their breakage mechanisms. The final results showed that applying the high voltage pulses at specific energy of 3–5kWh/t could significantly increase and extend the cracks and microcrakcs inside the rocks and consequently lead to decline in the Bond crushability and Abrasion indices of the crushed samples by 10.6% and 28.1%, respectively.

Experimental investigation on porosity reduction of a coarsely crushed rock layer subject to vertically cyclic loading

The long-term cyclic loadings from traffic and maintenance may weaken the occurrence of buoyancy-driven natural convection of the pore air in the coarsely crushed rock layer during winter months and the effectiveness of cooling down the embankment and underlying foundation soils, thus resulting in instability and failure of the highway/railway embankment structure. Obviously, successful application of the coarsely crushed rock embankments in cold regions has to study both theoretically and experimentally the impact of cyclic loadings on the particle shape, grain size distribution and rearrangement of the crushed rock aggregates and the porosity variation of coarsely crushed rock layer. Therefore, some experiments on the crushed rock samples with dimensions of 75×75×87cm under vertically cyclic loadings have been carried out. Three coarsely crushed rock samples with initial grain sizes of 16–40, 25–50 and 50–80mm were used to measure the related parameters to study their variations in cooling capability after the vertically cyclic loadings, respectively. The experimental approach on examining the particle shape and grain size distribution variations and the rearrangement of the crushed rock aggregates and the porosity reduction of the crushed rock layer under vertically cyclic loadings is developed. The porosities of three crushed rock samples with vibrating loading cycles have been measured using the water flooding approach.The results show that the cyclic vibrating loadings can cause the breakage and abrasion of the particles and their edges in the coarsely crushed rock layer and the particles also tend to be rounding and non-angular. These result in rearranging of particles and decreasing of particle size and increasing of fines content in the coarsely crushed rock layer, thus reducing the porosity of the crushed rock layer. Compared with the initial average porosities before cyclic loading, the reduction rates of final average porosity in three crushed rock samples after cyclic loading with 18,000cycles reach to 6.53, 7.45 and 8.08% corresponding to initial grain sizes of 16–40, 25–50 and 50–80mm, respectively. These reduction rates of the final average porosities in the vibrated crushed rock samples after cyclic loading increase relatively with increasing of an initial grain size. Under such conditions, the long-term cyclic loadings from traffic and maintenance can weaken the effectiveness of cooling down the embankment and underlying foundation soils due to natural convection in the coarsely crushed rock layer during winter months.

Assessing the efficacy of dyes extracted from some local plants for colouring cotton fabrics

Natural dyes from plant, animal and mineral sources have been used for centuries across the world. This study however, describes art studio quasi experiments conducted with the leaves, barks, seeds, roots, and fruit pods of 21 local plants to ascertain their potential for yielding dyes that would colour cotton fabrics and withstand frequent laundering. The methodology involved boiling the crushed leaf samples or chopped woody samples for between 15 and 30 minutes, draining the liquor into a plastic bowl, immersing the test cotton fabric and dyeing it hot or cold. With the exception of Adansonia digitata dye which was too weak to stain the fabric and Bixa orellana dye which was not colourfast and faded beyond recognition within six weeks, the other 19 plants yielded highly coloured, light- and wash-fast dyes of varying strengths, suggesting their feasibility for teaching basic skills in tie-dyeing, batik, watercolour painting and printmaking, which constitute integral aspects of the Visual Arts curriculum in Ghana. The study identified sodium carbonate as an effective mordant for improving the colour, strength and fastness of the brown Bridelia ferruginea dye which is the backbone of the indigenous textiles industry.Keywords: Natural dye, local plants, colour work, visual arts curriculum, Ghana

Loading capacity strengthening to cement-stabilised crushed gravel using reinforced wire mesh

Settlement and non-uniform deformation of frozen soil subgrade introduce fatal cracks on semi-rigid base asphalt pavements. This research aims to use reinforced wire mesh to reduce serious cracks on semi-rigid asphalt pavements in frozen regions. Three impact factors, diameter and interval as well as two types of wire mesh have been analysed by loading tests. Results have shown that after setting the reinforced wire mesh: (a) failure load and displacement of the cement-stabilised crushed gravel samples have been improved; (b) diameter and interval of the wire mesh have interactive impacts on reinforced sample load capacity; (c) the reinforced wire mesh can limit cracks by redistributing stress in the specimen; and (d) the multiple linear regression model well reflects the variation of loading properties; the results make sense from the statistics view as well. Results also represent that the strengthened wire mesh can help spread out the applied load, and increase the overall loading capacity of cement-stabilised crushed gravel. The results provided a reference for semi-rigid base asphalt pavement cracks caused by non-uniform deformation on frozen soil subgrade as well as guidelines for construction and maintenance in frozen regions.

Tocopherols in cocoa butter obtained from cocoa bean roasted in different forms and under various process parameters

Obtaining good quality chocolate strongly depends on raw material, i.e. cocoa beans. The processing of cocoa beans consists of some important steps, including fermentation, drying fermented beans and roasting. Traditionally roasting is performed on whole beans but currently, roasting crushed cocoa beans or cocoa liquor becomes more and more popular. Many biologically active compounds may be found in the cocoa beans, including tocopherols. This work investigates the influence of the constant or variable roasting process parameters (temperature, velocity and relative humidity of roasting air) on the tocopherol concentration in cocoa butter (CB) extracted from cocoa beans originating from Togo and roasted in two different forms, namely as whole and crushed beans. Whole cocoa beans were roasted to a 2% moisture content and crushed cocoa beans were firstly partially dried which further enables easier dehusking, then ground, dehusked and roasted until their humidity decreased to around 2%. Roasting resulted in lowering the content of individual tocopherols in analyzed material. The degree of degradation of tocopherols in CBs was different, depending on the form of roasted beans from which these CBs were extracted. Higher concentrations were determined in CBs extracted from beans roasted in the form of crushed samples comparing to CBs obtained from beans roasted as a whole. The study investigates different roasting parameters of crushed beans, none of which drastically lowered the concentration of tocopherols in extracted CBs. Their concentration in CBs extracted from whole beans was, on the other hand, influenced by roasting air parameters. In case of whole beans roasted under constant parameters, application of 150°C proved to be more favorable than roasting at 135°C, as well as application of “dry” air and 1m/s roasting air velocity. Discussing the variable roasting process parameters, in case of applied roasting temperature it is more favorable to change it from 150°C to 135°C, than the other way round. Changing the relative humidity of roasting air from 5 to 0.3%, lower degradation of tocopherols in CB occurs when the process is conducted at 150°C. It may be further concluded that a direct dependence between the velocity of roasting air varied during the process and the concentration of tocopherols in extracted CB may not be indicated. In conclusion, it is stated that the temperature of the air applied during the roasting process has the decisive influence on the tocopherol content in CBs extracted from cocoa beans subjected to the process.

Impregnation of Crushed Stone with Bitumenous Compounds Using Propane/Butane Impregnation Process Carried out in Supercritical Fluid Conditions

An efficient technology of impregnation of carbonate crushed stone by oil-product based on SCF-impregnation process usage with propane/butane solvent was developed. Regular impregnation throughout the volume of crushed stone sample is achieved. As a result of the appliance of proposed technology, the humidity of the treated crushed stone samples decreased down to 0.54%.

Extraction of copper from small electronic devices populated on discarded PCBs

With the technological development, the demand for electric and electronic equipment (EEE) is increasing rapidly worldwide. Printed circuit boards (PCBs) is one of the essential parts of all the EEEs which contains large number of small components for different applications. Huge amount of such small components are generated during PCBs production as well as after its end of life. Recycling and reuse of these devices from waste circuit boards is essential to conserve the resources and avoid environmental problem. Present study shows the recovery of valuable copper from small electronic devices such as capacitor, LED, MOSFET etc populated on discarded PCBs. The crushed samples were leached using nitric acid. 99% copper dissolution was observed at elevated temperature, pulp density of 15g/L in 60 min with stirring speed of 300 rpm. The metals or its salt can be further produced from the leach liquor by the process of precipitation, evaporation, solvent extraction etc.

An Approach of Laser-Induced Breakdown Spectroscopy to Detect Toxic Metals in Crushed Ice Ball

This paper deals the application of laser-induced breakdown spectroscopy (LIBS) to toxic metals used as pigment in crushed ice-ball samples. The present work highlights the advantages of LIBS as in situ, real-time analytical tool for rapid detection of toxic or heavy metals like lead (Pb) and chromium (Cr) and non toxic elements like carbon (C), nitrogen (N), magnesium (Mg), calcium (Ca), sodium (Na), and potassium (K) in crushed ice-ball of different colors (red, green, yellow, pale yellow, and orange) collected from five different areas, with minimal sample preparation. For rapid surveillance of toxic metals we have used multivariate analysis, that is, principal component analysis (PCA) with the LIBS spectral data of ice-ball samples. This study suggests that LIBS coupled with PCA may be an instant diagnostic tool for identification and classification of adulterated and nonadulterated samples.

Laboratory Measurement of Sorption Isotherm Under Confining Stress With Pore-Volume Effects

Summary For unconventional gas resources such as coal and organic-rich shale, sorbed phase is an important component of storage and transport calculations. Routine measurements of sorption are, however, performed separately from the porosity and permeability measurements. In this work, a new gas-storage measurement technique is proposed that combines the porosity and sorption measurements. Because the measurement is performed by use of core plugs under confining stress, it allows investigating the storage capacity for varying effective stress and incorporating the storage data into a subsequent permeability measurement under the same conditions. During the construction of the sorption isotherm in the laboratory with the volumetric (gas expansion) method, at each pressure step, the sorbed gas taken up by the sample reduces the pore volume (PV) of the sample. As a result, the initially determined PV at low pressure must be corrected at the beginning and at the end of the pressure step. This correction can be performed relatively easily during the routine sorption measurements with the crushed samples; however, it is a challenging task with core plugs under confining stress because at each pressure step the PV could also change as a result of pore compressibility. Our approach is based on a new analytical model of total gas storability developed to interpret the measured multiple-step pressure data on a graphical domain in which the storage-parameter estimation can be performed fast and accurately with a straight line. The approach considers both the compressibility and the sorbed-phase effects on the porosity and the sorption parameters. Experimental storage data of shale and coal samples with varying total organic content (TOC) and maturity are used to demonstrate the applicability of the analytical method to the measurements. The results show that the sorption measurements can be performed with increased accuracy and relatively fast. The work is important for organic-rich sample characterization in the laboratory, and for gas-in-place and transport calculations.

Process Conditions Governing Mechanical Expression of Shea Butter from Crushed Shea Kernel under Uni-Axial Compression

Mechanical expression of shea butter from shea kernel (Vitelaria paradoxa) was studied using a 43factorial experiment under a Randomized Complete Block Design. The mechanical expression rig comprised an instrumented pistoncylinder assembly in conjunction with a Universal Testing Machine (UTM). Shea butter was mechanically expressed through the perforated base of the press cage cylinder when crushed shea kernel was subjected to uniaxial compressive loading by the UTM. The process conditions were heating temperatures of 50, 70, 90 and 110 °C; applied pressures of 1.5, 2.9, 5.8 and 8.8 MPa and loading speeds of 2.50, 5.00, 7.50 and 10.00 mm min-1. Heating of the crushed shea kernel samples prior to shea butter extraction was achieved by a temperaturecontrolled band heater enfolding the press cage cylinder. Results showed that a maximum oil yield of 35.10 %, a maximum oil recovery efficiency of 58.50 % and a minimum process loss of 2.83 % were obtained at a heating temperature of about 70 °C, an applied pressure of about 8.8 MPa and a loading speed of about 2.50 mm min-1.

The impact of particle size and maceral segregation on char formation in a packed bed combustion unit

Highveld parent coal was crushed into three size fractions, namely: 5mm–75mm, 5mm–53mm, and 5–37.5mm. The crushed samples were subjected as feed coals to heating in a packed-bed reactor to investigate the influence of particle size reduction on char formation and reactivity. Coal petrography was utilized to assess the maceral and char formation distribution of the feed coal samples and their packed-bed combustion unit’s products. The maceral distribution of the feed coal fractions differed from the typical run-of-mine Highveld coal petrographic composition; the smallest size fractions (−53mm and −37.5mm) having the highest vitrinite content. Maceral distribution was further divided into total reactive maceral particles, total inert maceral particles, and total inertinite particles. The −53mm and −37.5mm feed coal samples had the highest total reactive maceral particle content. Inert char particles dominated in the packed-bed combustion unit samples due to high inertinite maceral group content of the Highveld coals. Unexpectedly, the −53mm feed coal sample had higher content of total reactive maceral particles and lower content of total inert maceral particles; whereas the −37.5mm feed coal sample had high content of reactive maceral particles and high content of total inert maceral particles. This variation in maceral group content lead to the −53mm feed coal sample being more reactive (producing more devolatilized and porous chars and thus reacting faster with reactant gases) than the −37.5mm feed coal sample. This was due to inert maceral particles restricting the −37.5mm feed coal sample from fully softening and reacting with reactant gas. This was also this was attributed to variation in volatile propagation of the three particle sizes. This confirms that a feed coal with smaller particle sizes results in different reactivity, char formation, and better heat transfer during combustion than the feed coal with large particle size range. Another important factor that plays a role in combustion is maceral association; it was observed that maceral distribution has a great influence on the char formation and its reactivity more than coal particle size.

Experimental study on adsorption of a new surfactant onto carbonate reservoir samples—application to EOR

AbstractSurfactant flooding aims at lowering the interfacial tensions between the oil and water phases to improve the displacement efficiency during oil recovery. However, surfactant losses due to adsorption on the reservoir rock impairs performance of the chemical flooding, consequently renders the process impractical economically. This article presents adsorption equilibrium and kinetics of Zizyphus Spina Christi (ZSC), a new non‐ionic surfactant, onto carbonate rocks. The adsorption tests were conducted at a temperature range of 28–75°C. A conductivity method was employed in this study to measure CMC parameter and surfactant concentration in the aqueous solutions. The equilibrium conditions for the crushed rock samples were obtained after about 2 days. According to the experimental results, the equilibrium data were well‐fitted by the Freundlich isotherm for carbonate samples. Furthermore, the adsorption process is exothermic and obeys the second‐order kinetic model. Such a systematic investigation is very helpful to select a proper surfactant for EOR application and reservoir stimulation in the petroleum industry.

A newly developed soil abrasion testing method for tunnelling using shield machines

The importance of the effect of ground abrasivity on the performance of a tunnel boring machine (TBM) is important for many tunnelling projects. In recent years, many abrasivity devices have been developed to measure soil abrasivity for specific conditions. In this paper a new device is developed to estimate the abrasivity of the soil for a wide range of site conditions. The device is designed on the basis of simulating the site conditions regarding the ground water, ground stresses and confining pressure of the TBM chamber, and the performance of the rotating cutter-head and pressurized shield tunnelling during its operation. A number of abrasivity tests were carried out on 12 types of crushed rock samples including six sedimentary rocks and six crystalline igneous and metamorphic rocks. The results showed that the abrasivity of the samples increased as equivalent quartz percentages of the sample increased. It was also found that the texture of the samples has a great influence on their abrasivity. To evaluate the performance of the newly developed device, the same samples were tested by other current abrasivity methods including the Cerchar test, Laboratoire Central des Ponts et Chaussées (LCPC) test and soil abrasion test (SAT). Comparisons of the results indicated close correlations, especially with the results for the Cerchar and LCPC devices.

Influence of Pressure on Application of Mercury Injection Capillary Pressure for Determining Coal Compressibility

Mercury injection capillary pressures (MICP) on the coal samples were measured with a variety of pressure regimes. The goal was to compare the effects of different pressure regimes for determining the compressibility of the coal. The two samples were taken from Northeast China. MICP profiles up to 204 MPa were measured on two different crushed samples of the same size. Three linear regimes namely, at 10-40 MPa, 40-100 MPa and P&gt;100 Mpa are defined, corresponding with the diameters of mesopore and microspore. The standard deviations of the compressibility values were less than 20%. The results from the present study suggest that the different pressure regimes affect the compressibility values slightly.