Effect Of Mineralogy Research Articles

Effect of Mineralogy on the Beneficiation of REE from Heavy Mineral Sands: The Case of Nea Peramos, Kavala, Northern Greece

Beneficiation of a rare earth element (REE) ore from heavy mineral (HM) sands by particle size classification in conjunction with high-intensity magnetic separation (HIMS) was investigated. The HM sands of Nea Peramos, Kavala, Northern Greece, contain high concentrations of REE accommodated mainly in silicate minerals, such as allanite. However, the potential of the Northern Greek placer for REE exploitation has not been fully evaluated due to limited on-shore and off-shore exploration drilling data. Characterization of the magnetic separation fractions using XRD and bulk ICP-MS chemical analysis showed that the magnetic products at high intensities were strongly enriched in the light REE (LREE), relative to the non-magnetic fraction. Allanite and titanite are the major host mineral for REE in the magnetic products but mainly allanite controls the REE budget due its high concentration in LREE. SEM/EDS and ICP-MS analysis of the different particle size fractions showed LREE enrichment in the fractions −0.425 + 0.212 mm, and a maximum enrichment in the −0.425 + 0.300 mm. The maximum enrichment is achieved after magnetic separation of the particle size fractions. Mass balance calculations showed that the maximum REE recovery is achieved after magnetic separation of each particle size fraction separately, i.e., 92 wt.% La, 91 wt.% Ce, and 87 wt.% Nd. This new information can contribute to the optimization of beneficiation process to be applied for REE recovery from HM black sands.

Laboratory observation of velocity anisotropy affected by clays and microcracks in artificial clay-rich shale samples

Clays play important roles in velocity anisotropy. Unlike brittle minerals, e.g., quartz, ductile clays are commonly more easily affected by mechanical compaction. Hence, clays tend to have a platy structure that might introduce significant velocity anisotropy. Cracks developed in clay-rich shales also have substantial influences on the shale elastic anisotropy and hydraulic stimulation. However, crack developments are sometimes unknown, and the effects of clays and cracks are ambiguous due to the complexity of shale properties. In this study, we construct artificial clay-rich shale samples which contain 40% clays by weight (kaolinite, smectite, and illite, respectively). The artificial shale samples are cored into shale-90 samples (along the bedding-parallel direction) and shale-0 samples (along the bedding-normal direction), and the P- wave and S- wave velocities are measured as the axis pressure (Pa) increases from 15 MPa to 50 MPa, while the confining pressure (Pc) remains at 15 MPa. We evaluate the slopes of the fitting line of velocity versus pressure, and estimate the crack density. We analyze the velocity anisotropy effect from clays and cracks based on laboratory experiments. Clays with an apparent platy grain structure (e.g., illite) introduce higher anisotropy, indicating that velocity anisotropy is dependent on the clay lamination structure. The comparison suggests that the mineralogy effects are the dominant factors in the anisotropy of clay-rich artificial shale samples, and the microcrack effects further enhance the velocity anisotropy.

Effect of Mineralogy on Reduction Behaviour of Iron Ore Pellets

The present study deals with impact of gangue amount (Al2O3, SiO2) in iron ores on reduction of its pellets for production of sponge iron. Iron ore pellets were reduced isothermally with noncoking coal fines in the range of 1123 - 1273 K with a time interval of 15, 30,45,60,90 and 120 min. As the temperature rose from 1123 to 1223 K, the reducibility index of iron ore pellets increased and then decreased at temperature 1273 K. All iron ore pellets shows complete reduction at temperatures of 1173 and 1223 K within 120 minutes. The reduction results clearly show that the reducibility of the pellets depends on the initial mineralogy of the ore. It was also observed that the reducibility decreased as gangue content (Al2O3 + SiO2) increases. The activation energy of the pellets decreased from 46.54 and 49.13 kJ/mol when the gangue content increased. The pellets were metallographically characterized before and after reduction to identify phase transformations. Examination of the SEM microphotographs revealed that Whisker shape of iron grains were formed during the reduction process and clear porous structure was observed.

Effects of mineralogy on pore structure and fluid flow capacity of deeply buried sandstone reservoirs with a case study in the Junggar Basin

Integrated experiments including porosity, permeability, casting thin section (CTS), scanning electron microscopy (SEM), pressure-controlled mercury porosimetry (PCP), rate-controlled mercury porosimetry (RCP), nuclear magnetic resonance (NMR), and X-ray diffraction (XRD) are conducted to investigate the impacts of mineralogy on the pore structure and fluid flow capacity of the deeply buried sandstone in the Jurassic Sangonghe Formation of the Junggar Basin. The results indicate that the heterogeneous deeply buried sandstone is rich in quartz (54.2%), feldspar (25.1%), and clay (14.2%), with dominant kaolinite and chlorite cementation. The reservoir has a variable overall pore-throat diameter distribution with three peaks in the ranges 0.01–1, 10–80, and 200–1000 μm. Pores are tri-fractal and can be divided into micropores, mesopores, and macropores. The movable porosity is primarily contributed by intergranular and intragranular pores and widely ranges from 1.75 to 8.24%. Most of the fluids are movable in intergranular pores but are irreducible in intragranular pores. Correlation analyses indicate that quartz benefits the intergranular porosity preservation, increasing pore size and macropores porosity, and reducing heterogeneities of the macropores, micropores, and pore system. Feldspar exhibits poorly opposite influences due to the simultaneous clay precipitation and complex roles of feldspar dissolution in the microporosity. All of the clay minerals act as destructions to intergranular porosity, enhancing the mesopores and micropores porosities, reducing the pore size, and increasing the heterogeneities of the macropores, micropores, and pore system. Quartz is favorable for the fluid flow capacity of deeply buried sandstone, but feldspar and clay play negative roles. The reversed impacts of quartz and feldspar lay in their opposite controls on pore size. Both pore size and hydrophilia should be taken into account when considering the effects of clay. This negative effect is associated with types, contents, hydrophilic degrees of clay minerals, in which I/S and illite exhibit the strongest influences. The fluid flow in the intergranular and intragranular pores is generally enhanced by higher quartz content, and reduced by higher clay content.

Investigating effects of temperature and confining pressure on dynamic elastic properties and permeability—An experimental study

Unconventional reservoirs refer to hydrocarbon reservoirs that require special stimulation treatments, such as hydraulic fracturing, to economically produce hydrocarbon. These reservoirs are tight with very low permeability, less than 0.1 milli Darcy (0.1 mD). Shale oil and shale gas reservoirs are prime examples of unconventional reservoirs. Effects of temperature on unconventional reservoirs’ dynamic elastic properties and permeability are usually overlooked during laboratory measurements and reservoir simulations leading to erroneous results and unsuccessful stimulation operations.To investigate effects of temperature and confining pressure on dynamic elastic properties and permeability of unconventional core samples, two series of experiment were conducted on outcrop core samples from three prominent unconventional basins (Barnett, Wolfcamp, and Eagle Ford) in the United States. In the first set of experiments, eleven unsaturated outcrop core samples (four Barnett, four Eagle Ford, and three Wolfcamp) were used to assess effects of temperature and confining pressure on their dynamic elastic properties. In the second set of the experiments, seven core samples (two Barnett, two Eagle Ford, and three Wolfcamp) were used to study effect of temperature on their permeability at a constant confining pressure. Also, X-ray diffraction (XRD) analysis was conducted on core samples to determine the mineral compositions them. The results were then used to study effect of mineralogy on the rock samples’ dynamic elastic properties and permeability.The results of this experimental study show that increase in temperature makes the core samples more ductile and less permeable. The results also demonstrate that the degree of the effect of the temperature on the dynamic elastic properties of the samples is directly related to the presence and volume of the clay minerals.

A chronosequence study of purple paddy soils with respect to improving ammonium and potassium fertilization management

Purple paddy soils cover about 66% of the paddy soils in Sichuan Basin. Complex interactions made the effects of potassium fertilizer application on NH4+ adsorption more complicated and the behavior of NH4+ and K+ interaction in purple paddy soils has rarely been evaluated. We hypothesize that correct management of these soils can enhance the efficiency of ammonium and potassium fertilizers. In order to determine correct management methods, it is important to understand the interaction of main nutrient cations NH4+ and K+ and maturation hydroponics in purple paddy soils with different paddy cultivation times. A purple paddy soil chronosequence with cultivation history from 0 to 300 years was studied to understand the respective effects of SOM and mineralogy on NH4+ and K+ sorption behavior by adsorption experiments using samples both before and after H2O2 oxidation. The study shows that maturation hydroponics influenced NH4+ and K+ adsorption mainly through changing clay mineralogy and enhancing SOM accumulation. SOM and smectite play positive effects for NH4+ adsorption. The K+ adsorption, however, is mainly affected by the smectite changes. The adsorption percentages are obviously higher at 25–50 mg L−1 for each NH4+ solution and higher at 50–100 mg L−1 for each K+ solution. When ammonium and potassium were applied together, NH4+ and K+ adsorption are mutually weakened. In addition, the percentage of K+ adsorption increased from 49.7–57.7% for the 100 mg L−1 K+ solution to 50.9–58.5% for the 200 mg L−1 K+ solution at 200 mg L−1 of added NH4+. SOM enrichments could be a positive way to improve the ammonium fertilizer utilization efficiency in purple paddy soils. Potassium may be more vulnerable to loss at low K+ concentrations given that ammonium and potassium fertilizers were applied together and it should be separately applied to enhance the utilization efficiency of applied fertilizer.

Effect of rock mineralogy on mortar expansion

Alkali-silica reaction (ASR) is among one of the most important damaging mechanisms in concrete, depending primarily on aggregates which contain reactive minerals. However, expansion in concrete may not directly relate to the reactive minerals. This study aims to investigate the influence of ASR and the expansion of mortar bars depending on aggregate type containing various components such as quartz, clay minerals (montmorillonite and kaolinite) and micas (muscovite and biotite). In this study, the accelerated mortar bar tests (AMBT) were performed in two conditions (mortar bars in the same and sole NaOH solutions). Petrographic thin section studies, X-ray diffraction (XRD) analysis (Rietveld method), scanning electron microscopy (SEM) and chemical analyses were carried out. This study showed that quartzite bars led to increase in expansion values of mortar bars in diabase-1 and andesite when these were in the same NaOH solution. However, three samples (basalt, quartzite and claystone) were found having ASR expansion based on the AMBT when the special molds were used for each sample. SEM study revealed that samples which exhibit highest expansions according to AMBT had a generally rough surface and acicular microstructures in or around the micro-cracks. Basalt and quartzite showed more variable in major oxides than those of other samples based on the chemical analyses, SEM studies and AMBT. This study revealed that the highest expansions were observed to source not only from reactive aggregates but also from alteration products (silicification, chloritization, sericitization and argillisation), phyllosilicates (muscovite, biotite and vermiculite) and clays (montmorillonite and kaolinite).

Characteristics of tight oil sandstone reservoirs: a case study from the Upper Triassic Chang 7 Member in Zhenyuan area, Ordos Basin, China

Tight oil reservoirs account for a large portion of hydrocarbon resources in continental basins. The Chang 7 Member of the Upper Triassic Yanchang Formation in the Ordos Basin is a well-known high-quality source rock in China and considerable petroleum resources have been found in its tight oil sandstone reservoirs. This study uses thin sections, constant-rate mercury injection, mercury injection, scanning electron microscopy, and the fractal dimension to study its mineral compositions and pore structure and to discuss the effects of cement mineralogy and pore structure on reservoir physical property. Tight oil sandstone reservoirs in Chang 7 Member mainly consist of gray and grayish green medium-fine-grained lithic arkose, feldspathic litharenite, and litharenite. Feldspar dissolved pores are the most developed pores in the reservoirs, followed by intergranular pores and lithic dissolved pores. Throats of the reservoirs are mainly in pore shrinkage type, neck type, sheet type, and bent sheet type. The tight oil sandstone reservoirs have complex pore structure and with the increasing radius, the structure of throats becomes simpler, while the structure of pores becomes more complex. According to median radius of pore-throat, the maximum mercury intrusion saturation, and extrusion efficiency, the reservoirs can be divided into three types: micro throat-high mercury intrusion saturation type with high physical property, adsorptive throat-medium mercury intrusion saturation type with medium physical property, and micro adsorptive throat-low mercury intrusion saturation type with low physical property. Ferrocalcite and illite are the main cements reducing reservoir physical property, while chlorite cement can protect the reservoir physical property to some extent. In microscopic pore structure parameters, except pore-throat skewness, median radius of pore-throat, pore-throat ratio, pore-throat sorting coefficient, and the fractal dimension of big pore-throats, can affect reservoir physical property.

Experimental determination of the dew point pressure for bulk and confined gas mixtures using an isochoric apparatus

A robust high precision experimental approach to determine the Dew Point Pressure (DPP) of the gas condensates in a nano-porous medium is presented in this study. Gas condensate reservoirs have been the center of attention for numerous numerical and experimental studies for decades. Therefore, accurate measurement of DPP is crucial in developing long-term production plans for these reservoirs. This paper presents for the first time a proof of concept for a procedure to study the effect of the pore size distribution on the degree and direction of the shift in the saturation pressure of hydrocarbon gas mixtures under confinement over a relevant range of pressures and temperatures.Isochoric method, an indirect high-precision way of phase transition point determination, is commonly used in other disciplines where a clear non-visual determination of phase transition of a fixed volume of fluid is needed. This study provides an insight into using this approach for determining DPP of gas mixtures inside and outside of the porous media. A semi-automated apparatus for measuring and monitoring equilibrium conditions along with fluid properties is designed based on the isochoric method. The apparatus provides constant volume, variable pressure (0–104 bar), and variable temperature (290–410 K) experimental conditions. Pressure and temperature measurements provide a way to detect the phase transition point along the constant-mole-constant-volume line based on the change in the slope of this line at the phase transition point. A packed bed of BaTiO3 nanoparticles, providing a homogenous porous medium with pores of 1–70 nm is used as a representative nano-scale porous medium. The synthesized porous medium is very helpful in uncoupling the effect of pore size from the effect of mineralogy on the observed deviations in behavior, providing a volume more than 1000 times larger than the typical nano channels.The result is a set of isochoric lines for bulk and confined sample, plotted on the mixture's corresponding phase envelope to demonstrate the change in the saturation pressure. Phase envelopes (P-T diagrams) of the same mixture using different equations of state are created and the accuracy of each of these equations of state in providing an estimate of the experimentally detected DPP is discussed. Many attempts in explaining the shift in saturation pressures of the reservoir fluid confined in the narrow pores of unconventional reservoirs compared to those of the bulk can be found in the literature. However, there are some contradictions between the predicted behavior using different mathematical approaches. Experimental data could be substantially helpful in both validating the models and improving the understanding of the fluid behavior in these formations. Contrary to what many published models proposed, our results show that confinement effect shifts the DPP towards higher values compared to the bulk for a fixed temperature in the retrograde region. Capillary condensation is identified as the main source of the deviations observed in the behavior of fluids inside the nanopores. We evaluated some published models, including those based on EoS modifications, by comparing those to the experimental results which provides a quantification of their accuracy in estimating saturation pressure values for the confined mixtures.

The effect of mineralogy and textural characteristics on the strength of crystalline igneous rocks using image-based textural quantification

The attempts made to understand and quantify the relationship between rock texture and engineering properties have been accompanied by some ambiguities and uncertainties, and the majority of the approaches, though focusing on particular rock types, have not been so successful for even the same rock types from other regions. This study, therefore, was aimed to investigate the relationship between the texture and strength properties of a wide range of crystalline igneous rocks along with more aspects of textural analysis. For this purpose, fifteen fresh samples of crystalline igneous rocks belonging to the stone quarries of the NW Iran were collected and subjected to compressive and tensile strength tests (UCS and BTS). Thin sections of the samples were used to prepare the full mosaic image layers in three different optical conditions. About 18,000 mineral grains were manually traced on the processed images and the obtained vector data was used for the quantification of various textural parameters including size metrics, shape descriptors, microfabric indices and mineral content. Different phase considerations (full-phasic, monophasic, multiphasic and phase-ratio) were applied to derive the textural characteristics of the individual and multiple minerals and their proportional ratio. Finally, simple linear regression analysis was performed to evaluate the relationship between the texture and strength properties. The results indicated that the newly developed quartz to feldspar size ratio (QFSR) indicator was the only textural parameter that could be significantly correlated with both compressive and tensile strength in a wide range of rock types. The results also highlighted the fact that the role of quartz and feldspar encountered with different rock failure mechanisms could be different; In fact, the tensile strength was obviously affected by the size and content of K-feldspar, while the compressive strength showed a more complicated mechanism and seemed to be controlled by the interference effects of plagioclase and quartz textural properties. Furthermore, the study indicated that the influence of grain size on the rock strength was more important than the grain shape or mineral content.

Water retention characteristics of iron ore fines

Evaluations of water retention characteristics of typical iron ore fines (IOF) were presented, which was part of experimental works for the estimation of liquefaction potential of IOF heaps. The water retention tests were conducted in a suction range from 0.1 to 106kPa on two IOFs and two artificial soils with various testing techniques. It is observed that water retention characteristic curves of one IOF (IOF-B) converge in terms of the relationship between suction (S) and water content (w) regardless densities of specimens when S exceeds a threshold value (Sth). Based on this finding, water retention characteristics are divided into density and materials affected zones. It is also found that IOFs generally have higher water retention ability than the two artificial soils, from which discussion is made on the effect of specific surface area and mineralogy on water retention characteristics of IOF. Finally, water retention characteristics are linked to compaction curves, from which, with the consideration that degree of saturation at peaks of compaction curves is relatively constant, a safety margin of a recently proposed regulation for maritime transportation of IOF is discussed.

On the intrinsic behaviour of decomposed volcanic rocks

The intrinsic behaviour of soils is very essential and the mechanical behaviour of reconstituted soils depends mainly on its intrinsic properties. The separate role played by particle shape, particle mineralogy and grading on the mechanical behaviour of soils resulting from weathered igneous rocks have not been extensively studied. The effects of particle shape, particle mineralogy and grading on the mechanics of decomposed volcanics have been systematically investigated through one-dimensional compression and triaxial tests. This was achieved by using samples of different weathering degrees. The results indicate that the influence of particle mineralogy on the one-dimensional compression behaviour is relatively small compared to grading. There is effect of grading on the shearing behaviour, and it is less pronounced than in compression. There is slight effect of grading at a small strain level. Generally, grading has a notable influence on the mechanical behaviour of volcanic saprolites, and it is more important than particle mineralogy for volcanic saprolites.

Impact of surface roughness on wettability of oil-brine-calcite system at sub-pore scale

Wettability alternation appears to be an important physicochemical process in carbonate reservoirs during low salinity water flooding. Contact angle measurement is widely used as a simple and direct method to demonstrate wettability alteration by low salinity water. The effect of various parameters, e.g., brine salinity, oil composition, and rock mineralogy on contact angle have been well documented. However, uncertainty over effect of rock surface roughness on contact angle of oil-brine-calcite is a major impediment to upscaling laboratory results and predicting wettability at field scale, knowing oil-brine-rock interaction is governed by electrostatic forces. We thus measured contact angle of oil on calcite substrates with different surface roughness (17 nm, 366 nm, and 943 nm), in high and low salinity brines. Moreover, we compared our experimental results with contact angles predicted by Wenzel's equation.Contact angle results show that in high salinity brine, contact angles decreased from 170° to 134° (36° decrease) with increasing surface roughness from 17 to 943 nm, suggesting a less hydrophobic system. Similar correlation between contact angles and surface roughness was observed in low salinity brine. Nevertheless, contact angles only slightly decreased from 117° to 101° (16° decrease) in low salinity brine, suggesting the effect of surface roughness on contact angle is more subtle in low salinity condition. We also found that for oil-brine-calcite system, the correlation between contact angle and surface roughness contradicts the trend predicted by Wenzel's equation. This is largely because the surface forces that govern oil-brine-calcite interactions are not captured by Wenzel's equation. Therefore, we hypothesize that at pore-scale level, wettability alteration by low salinity brine will likely be more subtle than that shown by contact angles when performed on smooth substrates (at sub-pore scale). To predict contact angle at pore-scale, surface roughness and surface forces governing oil-brine-calcite interactions need to be considered. The findings of this research will provide further insight into water-assisted EOR in carbonate reservoirs.

Foamed concrete incorporating mineral admixtures and pulverized ceramics: Effect of phase change and mineralogy on strength characteristics

Different microstructural changes occur in cement based materials as a result of the interaction between the aggregate particles and paste matrix, during mixing, compaction and placement. Such intrinsic modifications, in terms of paste density, interfacial transition zone, permeability and others, tend to improve or lessen the strength properties of concrete. This study evaluates the microstructure, mineralogy, phase change and strength characteristics of foamed concrete containing fly ash and pulverized ceramics. Portion of ceramics, which were generated from floor and wall tile wastes, and finer than 4.75 mm sieve, along with fly ash, were used as a partial replacement of river sand and cement, respectively. The foaming agent used was aluminum powder. However, other constituents were kept constant. Samples of 150 mm concrete cubes and 100 × 100 × 500 mm prisms were prepared, and cured in water for 3, 7, and 28 days, for compressive strength and flexural strength determination at the stipulated days. The microstructure, mineralogy and phase change of selected samples were determined using Scanning electron microscope, X-ray diffraction, and Thermogravimetric Analyzer-Differential Scanning Calorimeter, respectively. The ceramics based foamed concrete exhibited lower slump compared to conventional mixture, mainly due to its aggregate higher water absorption capacity. A 100% ceramics based mix gave strength in somewhat closeness to that of conventional mixture, and it was evidently shown by a lower amount of Portlandite (Ca(OH)2) dehydroxylated between 420 and 550 °C burner temperature for this mixture. The study demonstrates the possibility of incorporating ceramics along with mineral admixtures such as fly ash and aluminum powder for production of foamed concrete.

Mineralogical control on the magnetic anisotropy of lavas and ignimbrites: a case study in the Caviahue-Copahue field (Argentina)

SUMMARY Anisotropy of magnetic susceptibility is a petrofabric tool used to estimate the alignment of minerals at the site-scale, the imbrication between the magnetic foliation and the emplacement surface being an indicator of flow direction. However, despite numerous studies examining the flow direction in pyroclastic deposits and lava flows, the effect of magnetic mineralogy and the domain state of ferromagnetic phases on the magnetic fabric remains poorly understood. This paper describes the magnetic mineralogy and its influence on the magnetic fabric of Plio-Pleistocene lava flows and ignimbrites of the Caviahue-Copahue Volcanic Complex in the Andean Southern Volcanic Zone, Argentina. Rock magnetism, anisotropy of magnetic susceptibility and anhysteretic remanent magnetization and petrographic observations were performed on 30 sites of the volcanic complex. Results revealed the extrusive and pyroclastic rocks present varied magnetic mineralogy, formed in different stages of the magmatic evolution. Magnetic mineralogy variations strongly affect the anisotropy of magnetic susceptibility data in volcanic rocks and associated ignimbrites, providing ‘scattered’ fabrics when late Ti-rich titanomagnetite phases dominate the fabric, and ‘inverse’ or ‘intermediate’ fabrics when single-domain grains are present. ‘Normal’ fabrics are typically found when early crystallized pure magnetite is present. Our results highlight the complexity in the interpretation of magnetic anisotropy data in volcanic rocks and ignimbrites.

Rock physics of the Wolfcamp Formation, Delaware Basin

Production from wells in organic-rich shales often shows considerable lateral variation. Reliable predrill methods to characterize the lateral heterogeneity of such reservoirs are required to optimize the trajectory of lateral wells in these low-permeability reservoirs. Petrophysical interpretation of measured well logs provides information on mineral, porosity, and kerogen content. Combining the results of petrophysical analysis with P-wave, S-wave, and density logs allows generation of a probability density function (PDF) for each of the different significant lithofacies. The PDFs are applied to the P- and S-impedance from prestack seismic amplitude variation with offset inversion to predict the spatial variation in the distribution of lithofacies and associated probability for the Wolfcamp Formation in an area covered by a 3D seismic survey in the Delaware Basin, West Texas. An anisotropic rock-physics model for the Wolfcamp Formation allows the effect of complex mineralogy, organic carbon concentration, and porosity on the P- and S-impedance to be investigated. Kerogen inclusions and pores act to increase Thomsen’s anisotropy parameter [Formula: see text] relative to [Formula: see text], and there is a competition between clay matrix anisotropy and inclusion shape anisotropy in determining the anisotropy of the rock. Inclusions with isotropic elastic properties act to decrease the anisotropy due to the dilution effect, but this decrease is partially offset by the increase in anisotropy due to the anisotropic shape of the inclusions. Application of the model to the determination of minimum horizontal stress indicates that kerogen-rich siliceous shales have the lowest value of minimum horizontal stress, whereas silica-rich calcareous shales, mixed siliceous shales, and clay-rich siliceous shales have higher values and may therefore act as barriers for the vertical growth of hydraulic fractures.

Effect of rock mineralogy on Hot-CO2 injection for enhanced gas recovery

Conventional gas reservoirs are one of the viable options for CO2 enhanced gas recovery and sequestration. Injection of hot CO2 into depleted reservoirs is expected to improve gas recovery. Static adsorption and core flooding experiments were performed to quantify methane/CO2 adsorption/desorption using different rocks at different temperatures and pressures. Rocks such as shale, tight sandstone, calcite, and dolomite were used. For calcite, theoretical simulations were performed. Though methane desorption has increased when the temperature was raised, the results suggest that the gas recovery has doubled when the temperature has been increased from 50° to 100 °C in conventional reservoirs and from 100° to 150 °C in conventional and unconventional reservoirs. Similar trends were obtained for different rocks with increasing temperature. Core flooding and static adsorption experiments showed matching results. Rock mineralogy affects the adsorption capacity of the rock with shale rock having a 60% higher methane production than sandstone.

Synthesis of Scandium Phosphate after Peroxide Assisted Leaching of Iron Depleted Bauxite Residue (Red Mud) Slags

Anticipated future demand and limited primary sources of Sc highlight the importance of secondary Sc resources such as bauxite residue (red mud). In this study, a process route starting from red mud aiming to recover Sc as a concentrate by a combination of pyrometallurgical and hydrometallurgical processes was developed. Bauxite residue was treated in an electric arc furnace (EAF) for Fe removal as well as slag conditioning with varying flux additions and various cooling conditions. 95% of iron recovery to the metal was achieved. Resulting slags were subjected to identical H2O2 supported H2SO4 leaching conditions at 75 °C. The effect of slag mineralogy and crystallinity on the leaching efficiencies were investigated using XRD and QEMSCAN analysis. As a result of the highly amorphous nature of acidic slags, maximum of 72% Sc leaching was obtained. For leached slags, water quenched basic slag was found to be the most promising condition resulting in an extreme Sc leaching yield of 97% and this slag was selected for the further Sc precipitation. High impurity removal rates and selective Sc separation were achieved with a triple-stage successive precipitation to synthesize a Sc concentrate. Starting from EAF treatment followed by leaching and precipitation, 85% of the initial Sc in the red mud was successfully recovered as Sc phosphate.

Pre-concentration of nickel in laterite ores using physical separation methods

Nickel is an important metal globally with a consumption of about 2 million tons per year. This is supplied from both sulfide and laterite ores, but currently laterites are becoming more attractive for nickel production due to the depletion of high grade nickel sulfide ores. Laterites are generally processed through hydro or pyro-metallurgy and therefore, pre-concentration of nickel before such processes is very important.This paper examines the effects of different physical methods on pre-concentration of nickel in laterite ores. The effect of ore mineralogy on choosing the best strategy to upgrade nickel will be discussed. The findings of this project will help to unlock a substantial volume of nickel with significant value from laterite ores.

Effect of mineralogy on friction-dilation relationships for simulated faults: Implications for permeability evolution in caprock faults

This paper experimentally explores the frictional sliding behavior of two simulated gouges: one, a series of quartz–smectite mixtures, and the other, powdered natural rocks, aiming to evaluate and codify the effect of mineralogy on gouge dilation and frictional strength, stability, and healing. Specifically, velocity-stepping and slide-hold-slide experiments were performed in a double direct shear configuration to analyze frictional constitutive parameters at room temperature, under normal stresses of 10, 20, and 40 ​MPa. Gouge dilation was measured based on the applied step-wise changes in shear velocity. The frictional response of the quartz–smectite mixtures and powdered natural rocks are affected by their phyllosilicate content. Frictional strength and healing rates decrease with increasing phyllosilicate content, and at 20 ​wt.% a transition from velocity-weakening to velocity-strengthening behavior was noted. For both suites of gouges, dilation is positively correlated with frictional strength and healing rates, and negatively correlated with frictional stability. Changes in the permeability of gouge-filled faults were estimated from changes in mean porosity, indexed through measured magnitudes of gouge dilation. This combined analysis implies that the reactivation of caprock faults filled with phyllosilicate-rich gouges may have a strong influence on permeability evolution in caprock faults.