Clay Inclusions Research Articles

Novel low-carbon eco-concrete filled-FRP tubes under axial compression: Experimental behavior and analytical model

Concrete is essential in global construction but significantly contributes to carbon emissions, primarily due to cement production. The cement industry is adopting low-carbon practices, such as using supplementary cementitious materials (SCMs) to reduce emissions. Concrete prepared with calcined clay can achieve a carbon reduction effect of approximately 30 % compared to ordinary cement. Current studies highlight the reuse of kaolin clay, the predominant constituent of engineering sediment in Shenzhen, China, providing raw materials for sustainable low-carbon and eco-friendly concrete. However, high substitution rates of calcined clay can compromise concrete strength, posing a challenge for the application in load-bearing structures. This study proposed a novel low-carbon eco-friendly concrete (i.e., using calcined clay as supplementary cementitious materials) filled into FRP tubes (i.e., Low-Carbon Eco-Concrete-Filled FRP Tubes, termed LCE-CFFTs) aiming to enhance substitution rates of calcined clay and to improve compressive strength and ductility. This paper provides a detailed description of the preparation method, chemical reaction process, chemical composition, and microstructure of calcined clay. Experimental tests investigated the axial compressive performance of LCE-CFFTs, considering calcined clay substitution rates and FRP thickness as key parameters. The experimental work and theoretical analysis indicated that: the inclusion of 10 % and 40 % calcined clay led to a reduction in carbon emissions, resulting in a decrement of 5.8 % and 23.3 %, respectively; confinement provided by FRP tubes mitigated the reduction in axial compressive strength resulting from calcined clay inclusion, particularly evident at higher substitution rates (40 %); the effect of FRP tube confinement in improving peak stress and axial performance of LCE-CFFTs became more pronounced with higher calcined clay substitution rates; to more accurately predict the axial compressive behavior of LCE-CFFTs of this study, it is essential to consider the biaxial stress-strain state of filament-wound FRP tubes.

Energy- efficient cementitious mortar containing clay based shape-stable phase change material: Development, characterization and temperature controlling performance

The need for buildings to ensure a comfortable thermal environment is increasing, leading to a surge in energy consumption. This study proposes an innovative approach to tackle thermal energy storage challenges in buildings by formulating a unique cementitious mortar containing a shape-stable composite of Saudi Arabian natural clay and methyl stearate phase change material (PCM). The inclusion of natural clay, chosen for its cost-effectiveness and eco-friendliness, addresses the issue of methyl stearate leakage—a common concern with PCM usage. Despite PCM incorporation, the mixture maintains desirable fluidity and consistency, albeit with a slightly reduced dry unit weight and compressive strength. Differential scanning calorimetry analysis defines key characteristics of the resulting shape-stable NC/MS composite PCM, including a melting point of 33.81°C and a latent heat storage capacity of 56.15 J/g. Empirical testing demonstrates the efficacy of the natural clay/PCM composite in temperature moderation. During periods of elevated external temperatures, the NC/PCM specimen effectively lowers room-center temperatures by up to 4°C and sustains a cooler environment compared to the control room for almost 8 hours. Additionally, the composite PCM limits the maximum increase in room center temperature post-sunset to only 2.49°C, showcasing its capability in stabilizing indoor temperatures. This innovative PCM composite responds dynamically to ambient temperature variations, transitioning between solid and liquid states to release stored latent heat, consequently reducing building heating and cooling loads, enhancing energy efficiency. The natural clay/PCM composite presents a promising solution for advancing building thermal energy storage systems, aligning with energy efficiency and sustainable design objectives.

Application and efficacy of beidellite clay for the adsorption and detoxification of deoxynivalenol (vomitoxin)

The incidence of mycotoxin occurrence throughout the entire lifespan of some agricultural products could be due to climatic conditions and environmental factors (including high temperature, drought, and heavy rainfall) that enhance growth of fungi. Deoxynivalenol (DON) which is also referred to as vomitoxin is a mycotoxin produced from many Fusarium species. DON ranks high among the prominent mycotoxins in cereal products and is a ubiquitous toxin in livestock feeds. DON's adverse effects present major health challenges in both livestock and humans. The use of natural sorbents including smectite clays, is an economically feasible strategy to mitigate mycotoxin toxicities. Previous studies have demonstrated the potential of edible clays as protective components of human food and animal feed to alleviate toxicity associated with short-term exposure to mycotoxins including DON. Hence, this study was designed to investigate the sorption mechanisms of DON onto the binding surfaces of beidellite clay, assessing essential binding parameters such as enthalpy, free energy, binding capacity, affinity, and plateau surface density. These markers were used to predict availability of DON under the experimental conditions. Furthermore, the protection of beidellite clay against DON-induced toxicity was carried out using living organisms susceptible to DON toxicity, including Hydra vulgaris and Lemna minor. These studies investigated the dose-dependent detoxification of DON by 0.05–2 % inclusion of beidellite. Beidellite exhibited more than 75 % protection in Lemna minor and 53 % in Hydra vulgaris validating that this clay is effective in detoxifying DON. During emergencies, or after disasters, inclusion of edible clay like beidellite in food, water or capsules could reduce bioavailability of DON and halt potential exposures to humans and animals.

Optimizing properties of clayey soil using lime and waste marble powder: a sustainable approach for engineering applications

Several studies have explored the potential of waste marble powder (WMP) and lime (LM) as solutions for issues associated with clayey soils. While WMP enhances mechanical properties and addresses environmental concerns, LM effectively improves soil characteristics. This research investigates the efficacy of LM and WMP, both individually and in combination, in addressing challenges specific to clayey soils in Bouzaroura El Bouni, Algeria. These soils typically exhibit low load-bearing capacity, poor permeability, and erosion susceptibility. LM demonstrates promise in enhancing soil properties, while WMP not only addresses environmental concerns but also enhances mechanical characteristics, providing a dual benefit. The study utilizes a three-variable experiment employing Response Surface Methodology (RSM) Box-Behnken Design, with variations in clay content (88%–100%), LM treatment (1.5%–9%), and WMP inclusion (1.5%–9%). Statistical analysis, including ANOVA, reveals significant patterns with p-values <5%. Functional relationships between input variables (clay, LM, and WMP) and output variables (cohesion, friction angle, and unconfined compressive strength) are expressed through high determination coefficients (R2 = 99.84%, 77.83%, and 96.78%, respectively). Numerical optimization identifies optimal mixtures with desirability close to one (0.899–0.908), indicating successful achievement of the objective with 88% clay content, 3% LM, and 6% WMP. This study provides valuable insights into optimizing clay soil behavior for environmental sustainability and engineering applications, emphasizing the potential of LM and WMP as strategic additives.

Liquefaction susceptibility of clayey sands under saturated and partially saturated conditions

Experiences from previous earthquake events have indicated that sands containing non-plastic (silt) or plastic (clay) fines are susceptible to liquefaction. These experiences underline the need for improving the fundamental understanding of the seismic behaviour of silty and clayey sands and for developing appropriate methods to evaluate their liquefaction potential. This paper presents an attempt to elucidate the integrated effects of fines (non-plastic silt and plastic clay) inclusion and degree of saturation on the cyclic behaviour and liquefaction resistance of sands based on systematic experiments. One of the notable findings of the study is that, apart from the familiar mode of cyclic mobility, clayey sand can also undergo flow-type failure under either fully or partially saturated conditions. The unified correlation between the cyclic resistance ratio and the state parameter (ψ), established earlier for clean and silty sand in the framework of critical state soil mechanics, is found to work for clayey sand as well. Furthermore, it is shown that the impact of saturation on the cyclic strength of clean and clayey sands can be reasonably characterised using the compression wave velocity normalised by the shear wave velocity.

Nanobrick Wall Multilayer Thin Films with High Dielectric Breakdown Strength.

Current thermally conductive and electrically insulating insulation systems are struggling to meet the needs of modern electronics due to increasing heat generation and power densities. Little research has focused on creating insulation systems that excel at both dissipating heat and withstanding high voltages (i.e., have both high thermal conductivity and a high breakdown strength). Herein, a polyelectrolyte-based multilayer nanocomposite is demonstrated to be a thermally conductive high-voltage insulation. Through inclusion of both boehmite and vermiculite clay, the breakdown strength of the nanocomposite was increased by ≈115%. It was also found that this unique nanocomposite has an increase in its breakdown strength, modulus, and hydrophobicity when exposed to elevated temperatures. This readily scalable insulation exhibits a remarkable combination of breakdown strength (250 kV/mm) and thermal conductivity (0.16 W m-1 K-1) for a polyelectrolyte-based nanocomposite. This dual clay insulation is a step toward meeting the needs of the next generation of high-performance insulation systems.

PVDF/Clay Spheres Obtained through Phase Inversion for Cu Ion Removal.

In this study, spheres of poly (vinylidene fluoride)/clay were synthesized using an easy dripping method (also known as phase inversion). The spheres were characterized by scanning electron microscopy, X-ray diffraction, and thermal analysis. Finally, application tests were carried out using commercial cachaça, a popular alcoholic beverage in Brazil. The SEM images revealed that during the solvent exchange process for sphere formation, PVDF tends to form a three-layered structure with a low-porosity intermediate layer. However, the inclusion of clay was observed to reduce this layer and also widen the pores in the surface layer. The results of the batch adsorption tests showed that the composite with 30% clay content in relation to the mass of PVDF was the most effective among those tested, with the removal of 32.4% and 46.8% of the total copper present in the aqueous and ethanolic media, respectively. The adsorption of copper from cachaça in columns containing cut spheres resulted in adsorption indexes above 50% for samples with different copper concentrations. Such removal indices fit the samples within the current Brazilian legislation. Adsorption isotherm tests indicate that the data fit better to the BET model.

An Improved Model for Estimation of Mechanical Properties of Polymer-Clay Nano-Composites

Polymer-clay nanocomposites are more popular in many industries and applications due to improved mechanical and gas barrier properties over pure polymers and classical polymer-based composites. The mechanism by which clay platelets, with thicknesses in the nanometer range, as opposed to the hundred-nanometer range in the other two dimensions, introduce the mechanical and other properties improvement can be attributed to their high efficiency in creating discontinuities to flows through the bulk matrix polymer material. However, the extent of this improvement depends on the success of separation or achieving full exfoliation of the clay platelets through the bulk matrix. Since such full exfoliation is not achievable experimentally, the aspect ratio of the filler particles is not a simple value that mathematical models employ to describe mechanical properties. In this work, a modification is proposed to improve such models by using relationships utilizing different concentrations of varying filler platelets thicknesses. The improvements in elastic tensile modulus are discussed with consideration of the effect of clay platelet inclusions geometry as depicted through the proposed modification to considered models to capture the effect of nano-platelets on the properties of the composite.

Utilization of Kenaf Core Fiber – Marine Clay Mixture as a Landfill Liner Material

Nowadays, leachate production is a big concern and causes a serious hazard to the soil and groundwater which causes the subsurface soil to be polluted as a result of the loss of soil quality and environmental pollution. This study aims to study the potential of using kenaf core fiber and marine clay mixtures as improved landfill liner material. Relevant laboratory tests such as atterberg limit test, specific gravity test, and particle size distribution were performed to examine basic geotechnical properties of marine clay soil collected from Batu Kawan, Penang. Besides that, compaction test and hydraulic conductivity test were carried out for soil mixed with kenaf core fiber to determine the strength and permeability characteristics. The results found that the marine clay has significantly adequate physical properties to be used as a landfill liner. The permeability test for marine clay soil inclusion of kenaf core fibre indicated that the hydraulic conductivity of the samples admixture for 0%, 4%, 8%, and 12% ranged between 6.68 × 10-9 and 1.57 × 10-8 m/s. Compaction of marine clay mix kenaf core fibre samples resulted in maximum dry density, ρdmax that ranged between 0.936 and 1.595 g/cm3 and optimum moisture content, wopt that ranged between 19.8% and 24%. Hence the inclusion of kenaf core fiber in marine clay soil improves the maximum dry density value, decrease permeability of marine clay and could be potentially used for landfill liner material.

Mass exchange in two-layer medium moving through the narrow cylindrical channel

This work further develops previous studies devoted to numerical modeling of diffuse mass transfer in narrow pore channels. The problem of diffusion in a two-layer liquid moving through narrow cylindrical channel, into which a neutral component, which does not interact with heterogeneous inclusions, diffuses, is considered. The dispersion carrier fluid moves close to the wal, while a reologically complicated two-phase medium occupies most of the channel. During the flow of a fine-dispersed concentrated suspension in a quasi-balanced condition, the reological properties of the medium were accepted as parameters of some homogenous liquid, which can be deemed an adequate approximation. This model can be used for some situations of flow in the chanal of fluid bodies which are capillary-porous and broken, such as those that contain muddy or clay inclusions. Similar mathematical models can be applied to paste sliding flows because of poor capillary fluid fixation. In this paper, two cases are considered. In the first scenario, a portion of the channel midsection is exceeded by the diffusing component. In the second, this component in the same location exits the channel. The non-stable problem is numerically solved before the creation of the stationary state. The installation procedure was monitored up to the fifth decimal digit. The resulting solution determines the concentration fields of the diffuse component. It is demonstrated that distribution of the diffuse component concentration in the working area is influenced by the rate of the medium speed; diffuse flow through the wall, and effective diffusion coefficient. In this work, the case is considered when there is no interaction between the diffusing component and the dispersed medium. However, the interaction of these components of the medium in soils, biological systems, and natural layers containing organic inclusions is of great interest. Therefore, accounting of adsorption properties of the dispersed medium in relation to the elements involved in mass exchange can be in the focus of future study. Taking into account large-scale metabolic processes, such as those in blood in the veins, is crucial in many practically significant circumstances.

Вплив мінеральної речовини вугільних частинок на обводнення кам'яновугільних смол.

INFLUENCE OF MINERAL MATTER OF COAL PARTICLES ON COAL TAR WATERING © L.P. Bannikov, PhD in Technіcal Sciences (State Enterprise "Ukrainian State Scientific Research Institute of Coal Chemistry (UKHIN), 7 Vesnina str., Kharkiv, 61023, Ukraine), N.V. Mukina (PJSC “ArcelorMittal Kryvyi Rih”, 1 Ordzhonikidze St., Krivoy Rog, Dnepropetrovsk region, 50095, Ukraine) The mineral part of the coal matter can serve as an important indicator of surface phenomena occurring during separation and preparation for processing of coal tar. Moreover, the analysis of the mineral part of coal tar and pitch during further processing shows that the ratio SiO2/Al2O3 does not change. This makes it possible to determine by the value of the ratio the belonging of the clay component of the mineral part of coking coals to montmorillonite, if the ratio is in the range from 2 to 5,5 (typical case ≈3,3). It is determined that the flotation concentrate yield and selectivity for the coal-montmorillonite system are lower than for the coal-kaolinite system, which is explained in terms of the theory of lyophobic colloid stability. The reasons for the deterioration of flotation due to the presence of bentonite in the mineral part of coal are considered, which is extended to the conditions of formation of coal tar emulsions stabilized by mineral-coal particles. It is shown that the absence of bentonite (montmorillonite) inclusions should be considered a typical case of the composition of the mineral part of coal. The results of determining the composition of the ash isolated from a sample of resin with a high degree of watering showed that in the analyzed case, the high stability of the "water-in-tar" emulsion is due to the presence of bentonite inclusions. To confirm the feasibility of determining the ratio of SiO2/Al2O3 ash substances as an indicator of the influence of the mineral part of coal on the surface phenomena occurring in coal tar and its products, the case of atypical deposits during the filtration of coal electrode pitch before the formation of pellets was investigated. The analysis of sediments from the pitch melt revealed that the SiO2/Al2O3 ratio was 2.7-3.2. Keywords: coal matter, mineral part, clay inclusions, montmorillonite, surface phenomena, flotation, stabilization of «water–in–tar» emulsion. Corresponding author Bannikov Leonid P., e-mail: ukhinbannikov@gmail.com

Frequency-dependent P-wave anelasticity due to multiscale (fractal) heterogeneities in rocks

Understanding the effect that multiscale heterogeneities have on the wave responses of rocks at different frequencies is essential in the interpretation of seismic data. In fact, the behaviors of ultrasonic and seismic waves differ because the experiments involve different spatial scales. Then, a solution is to apply a theory that establishes a relation between the wave properties at different frequency bands considering a size range of heterogeneities. To investigate this problem, we have measured the compressional wave (P-wave) anelasticity (velocity and attenuation) of tight reservoir rocks at ultrasonic, sonic and seismic frequencies. The wave behavior as a function of porosity or clay content shows a consistent trend. With increasing confining pressure, the effect of porosity on attenuation decreases, while that of clay content gradually becomes important. To interpret the data, we propose a double-fractal poroelasticity model by incorporating the self-similarity characteristics of cracks and clay minerals. The comparison between the experimental data and model results reveals the fractality of the clay inclusions and cracks, with radii range of [10−6, 10−1.5] m and [10−6, 10−3.1] m, respectively, which is responsible for the anelastic behavior of the waves on a wide frequency band.

The effect of differential mineral shrinkage on crack formation and network geometry

Rock, concrete, and other engineered materials are often composed of several minerals that change volumetrically in response to variations in the moisture content of the local environment. Such differential shrinkage is caused by varying shrinkage rates between mineral compositions during dehydration. Using both 3D X-ray imaging of geo-architected samples and peridynamic (PD) numerical simulations, we show that the spatial distribution of the clay affects the crack network geometry with distributed clay particles yielding the most complex crack networks and percent damage (99.56%), along with a 60% reduction in material strength. We also demonstrate that crack formation, growth, coalescence, and distribution during dehydration, are controlled by the differential shrinkage rates between a highly shrinkable clay and a homogeneous mortar matrix. Sensitivity tests performed with the PD models show a clay shrinkage parameter of 0.4 yields considerable damage, and reductions in the parameter can result in a significant reduction in fracturing and an increase in material strength. Additionally, isolated clay inclusions induced localized fracturing predominantly due to debonding between the clay and matrix. These insights indicate differential shrinkage is a source of potential failure in natural and engineered barriers used to sequester anthropogenic waste.

Electrokinetic delivery of permanganate in clay inclusions for targeted contaminant degradation

The use of electrokinetics (EK) has great potential to deliver reactants in impervious porous media, thus overcoming some of the challenges in the remediation of contaminants trapped in low-permeability zones. In this work we experimentally investigate electrokinetic transport in heterogeneous porous media consisting of a sandy matrix with a target clay inclusion. We demonstrate the efficient EK-delivery of permanganate in the target clay zone (transport velocity 0.3–0.5 m day−1) and its reactivity with Methylene Blue, a positively charged contaminant trapped within the inclusion. The delivery method was optimized using a KH2PO4/K2HPO4 buffer to attenuate the effect of electrolysis reactions in the electrode chambers, thus mitigating the propagation of pH fronts and preventing the phenomenon of permanganate stalling. The experiments showed that the buffer electrical conductivity greatly impacts the potential gradient in the heterogeneous porous medium with implications on the observed rates of electrokinetic transport (variation up to 40%). The reactive experiments provided direct evidence of the permanganate penetration within the clay and of its capability to degrade the target immobilized contaminant. The experimental results were analyzed using a process-based model, elucidating the governing transport mechanisms and highlighting the effect of different mass transfer processes on conservative and reactive electrokinetic transport.

The relationship between inclusion/void orientation and speed in wheel-thrown pots

The activity of wheel-throwing a ceramic vessel is governed by a number of physical forces. These are the rotational kinetic energy (expressed in terms of angular velocity and the moment of inertia) and manual pressures. Given the importance of the potter's wheel worldwide, and the frequently postulated socio-cultural meaning of wheel-throwing in particular, foundational research on the physics behind wheel-throwing has been under-represented, and there is a lack of understanding of the relationship between speed of wheel rotation, lifting speed and the orientation of clay pores or inclusions. The speed of rotation is highly relevant as different wheels can achieve different speeds. Thus, knowing the speed during manufacture may allow scholars to reconstruct the original device, manufacturing technique, and perhaps even the potter's level of skill. Two contrasting views can be found in the literature: a) there is a direct positive relationship between these variables, and that the angle of the inclusions/voids can therefore tell us about the wheel's speed at the time of making the pot and hence the device used; b) because pots are never thrown in one single motion, the angle of inclusions/voids is an averaging of all actions executed by the potter, and thus cannot provide meaningful inferences about speeds or device. Experiments with professional potters were devised to explore the relationship between these variables. They show that the interaction between the various physical forces, clay and potter is complex, leading to a large variance even within the work of a single potter, with finger pressure recognized as a major influencing variable. It is clear that angles of inclusions or voids cannot be used to project backwards to the wheel speed, lifting speed, skill level or device used.

Adsorption and detoxification of glyphosate and aminomethylphosphonic acid by montmorillonite clays.

The co-occurrence of mixtures of glyphosate (GLP) and aminomethylphosphonic acid (AMPA) in contaminated water, soil, sediment, and plants is a cause for concern due to potential threats to the ecosystem and human health. Major routes of exposure include contact with contaminated water and soil and through consumption of crops containing GLP and AMPA residues. Calcium montmorillonite (CM) and acid-processed montmorillonite (APM) clays were investigated for their ability to tightly sorb and detoxify GLP and AMPA mixtures. In vitro adsorption and desorption isotherms and thermodynamic analysis indicated saturable Langmuir binding of both chemicals with high capacities, affinities, enthalpies, and free energies of sorption and low desorption rates. In silico computational modeling indicated that both GLP and AMPA can be readily absorbed onto clay surfaces through electrostatic interactions and hydrogen bonding. The safety and efficacy of the clays were confirmed using well-established living organisms, including an aquatic cnidarian (Hydra vulgaris), a soil nematode (Caenorhabditis elegans), and a floating plant (Lemna minor). Low levels of clay inclusion (0.05% and 0.2%) in the culture medium resulted in increased growth and protection against chemical mixtures based on multiple endpoints. Results indicated that montmorillonite clays may be used to bind mixtures of GLP and AMPA in water, soil, and plants.

Impact of Bentonite Clay on In Situ Pyrolysis vs. Hydrothermal Carbonization of Avocado Pit Biomass

Biofuels produced via thermochemical conversions of waste biomass could be sustainable alternatives to fossil fuels but currently require costly downstream upgrading to be used in existing infrastructure. In this work, we explore how a low-cost, abundant clay mineral, bentonite, could serve as an in situ heterogeneous catalyst for two different thermochemical conversion processes: pyrolysis and hydrothermal carbonization (HTC). Avocado pits were combined with 20 wt% bentonite clay and were pyrolyzed at 600 °C and hydrothermally carbonized at 250 °C, commonly used conditions across the literature. During pyrolysis, bentonite clay promoted Diels–Alder reactions that transformed furans to aromatic compounds, which decreased the bio-oil oxygen content and produced a fuel closer to being suitable for existing infrastructure. The HTC bio-oil without the clay catalyst contained 100% furans, mainly 5-methylfurfural, but in the presence of the clay, approximately 25% of the bio-oil was transformed to 2-methyl-2-cyclopentenone, thereby adding two hydrogen atoms and removing one oxygen. The use of clay in both processes decreased the relative oxygen content of the bio-oils. Proximate analysis of the resulting chars showed an increase in fixed carbon (FC) and a decrease in volatile matter (VM) with clay inclusion. By containing more FC, the HTC-derived char may be more stable than pyrolysis-derived char for environmental applications. The addition of bentonite clay to both processes did not produce significantly different bio-oil yields, such that by adding a clay catalyst, a more valuable bio-oil was produced without reducing the amount of bio-oil recovered.

A hybrid GA-ANFIS and F-Race tuned harmony search algorithm for Multi-Response optimization of Non-Traditional Machining process

The present study focuses on development of prediction models with respect to various cut quality characteristics such as material removal rate, kerf taper and surface roughness for a well-known non-traditional machining process namely abrasive aqua jet cutting (AAJC) of natural fibre composite laminates through combined taguchi-genetic algorithm (TGA) and adaptive neuro fuzzy inference system (ANFIS). The AAJC experiments are conducted based on box-behnken design methodology by considering jet pressure, stand-off distance, traverse speed and wt% of nano clay inclusion in composites as input parameters. The ANFIS parameters are optimized using a hybrid taguchi-genetic training algorithm. The statistical results of hybrid TGA-ANFIS models shows that they are outperformed in prediction of AAJC parameters when compared with the results of multiple-linear regression models. Further, the optimization of AAJC parameters is carried out using a trained ANFIS network and the F-race tuned harmony search algorithm (HSA). The superlative responses such as MRR of 76.9 g/min, KT of 2.23° and Ra of 3.17 µm are forecasted at the optimum cutting conditions such as jet pressure of 303.08 MPa, stand-off distance of 2.16 mm, traverse speed of 375.64 mm/min, and nano clay wt% of 1.27, respectively. The experimental results show that the error between predicted and actual results are lower than 6%, indicating the feasibility of adopting the proposed F-race parametric tuned HSA in optimization of AAJC process.

A study of the thickening process for fine tailings of gold-bearing ores

Refractory low-grade gold-bearing ores require deep processing with finer preliminary grinding. As a result, finely dispersed products are formed, including fine tailings, which raise particular environmental concerns. The article presents the results of experimental thickening studies for the concentration tailings of gold-bearing ores from the Yuzhno-Nevyanskoe and Panovskoe deposits. The material studied is distinguished by the presence of fine clay inclusions, which reduce the sedimentation rate of slurry solids. The main processing methods are gravity separation in centrifugal concentrators and flotation. Electrokinetic properties of the particle surface, in particular, the x-potential, in the tailings slurries entering the thickening process may be used to predict thickening performance with sufficient accuracy and significantly reduce the number of laboratory experiments. Measured values of the x-potential, electric double layer thickness, and other dielectric properties of the particle surface were used to establish that the most effective sedimentation of the tailings was achieved at a mass fraction of solids in the slurry of up to 25 % and a pH value of at least 10.5. The optimal flocculant feed amount required to increase the slurry sedimentation rate was also established. It is therefore recommended to use the following flocculants for the ore processing tailings of the Yuzhno-Nevyanskoe deposit: Praestol 2510 at more than 10 g/t and Magnaflok 10 at over 20 g/t. Flocculants are not required for thickening the ore processing tailings of the Panovskoe deposit.

Investigations of polyamide nano-composites containing bentonite and organo-modified clays: Mechanical, thermal, structural and processing performances

Abstract Polyamide 6 (PA) matrix was reinforced with Na-activated bentonite, amino functional silane treated bentonite and organo-modified clays at different concentrations. The preparation of composites was carried out using melt-blending method and the test samples were prepared by injection-molding process. Mechanical, thermal, structural and processing investigations of PA based composites were reported performing via tensile, hardness, and impact tests, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction analysis (XRD) and force measurements, respectively. According to mechanical test results, additions of fillers to PA matrix caused slight improvements for tensile strength and modulus parameters. Silane treated BNT exhibited improvement in mechanical results compared to Na-activated bentonite additions. Thermal studies revealed that decomposition and melting temperatures of PA shifted to higher values after inclusion of clay into polymer matrix. Results confirmed that organo-clay and bentonite additions with their lower filling ratios yielded enhancements for the mechanical and thermal performance of polyamide.