Amount Of Fine Particles Research Articles

Numerical Study of the Movement of Single Fine Particles in Porous Media Based on LBM-DEM

The fine particle liquid–solid flow in porous media is involved in many industrial processes such as oil exploitation, geothermal reinjection and particle filtration. Understanding the migration characteristics of single fine particles in liquid–solid flow in porous media can provide micro-detailed explanations for the fine particle liquid–solid flow in porous media. In this paper, an existing lattice Boltzmann method–discrete element method (LBM-DEM) is improved by introducing a new boundary thickening direct forcing (BTDF) immersed boundary method (IBM) to replace the classical IBM. The new method is used to investigate the migrations of one, two or three fine particles in a flow field in porous media and the reactions of one, two or three fine particles on the flow field. It is found that the movement distance of a fine particle in porous media does not show a linear correlation with the fine particle’s density. A fine particle with a higher density may move a shorter distance and then stagnates. Although a fine particle with a smaller diameter has a better following performance in a flow field, it is also likely to be stranded in a low-infiltration area in porous media. Under the same increase ratio, the increase in the diameter of a fine particle causes an increased pressure drop of the liquid–solid flow. In some cases, the increase in the quantity of fine particles can intensify the disturbance of fine particles on the flow field, improving the movement of fine particles.

Hydraulic Backfill Consolidation in Underground Mine Stopes

This paper highlights the importance of considering hydraulic backfill consolidation and wet arching when determining the stresses in underground mine stopes and acting on the barricade. The wet arching is introduced here as an arching effect during consolidation. Most studies consider hydraulic backfill consolidation as an instantaneous process and ignore its effects on stress within the stope and acting on the barricade. Mainly the reasons would be the granular behaviour and higher permeability of mine tailings used for hydraulic backfills. Yet, recent laboratory experiments and tests carried out under this study show that the consolidation is slow enough to significantly affect the hydraulic backfill stresses. According to the literature, hydraulic backfills have a considerable amount of fine particles which can slow down the consolidation process as evident in the tests. The paper discusses available stress variation between dry and wet fills while demonstrating its significance and requirements for further studies in consolidation and wet arching. Another important factor ignored in the literature is the hydraulic backfill property variations which were evident in tests carried out in this study. The results suggest segregation occurs within the fill which follows property variations over depth and considerably influences stresses. These effects must be considered when determining the stresses within the fill and developing a hydraulic backfill stress model.

Optimisation of particle distribution and performance in three-layer tubular particleboards using response surface methodology

To explore the impact of manufacturing parameters on the modulus of rupture (MOR), internal bond strength (IB), and 24-h water absorption thickness swelling (24 h TS) of tubular particleboards, the geometry of the particles and the combination and distribution of the particles were investigated and integrated with response surface modeling (RSM). The results show that coarse particles with high aspect ratios form the network skeleton structure of tubular particleboards and provide the basic mechanical strength of the panels. The addition of an appropriate amount of fine particles can reduce the internal voids of the board and improve its mechanical strength. In addition, the surface fine particles flowed from the gaps of the coarse particles to the interior of the boards, making the boards more compact, which was conducive to improving the modulus of rupture and internal bond strength of the tubular particleboards. It was also found that the tube spacing limited the distribution of particles of different sizes, and regulating the tube spacing could lead to boards with good performance. According to the response surface data, the derived mathematical model of the second-order response function has an R2 of 0.954 for MOR, 0.956 for IB, and 0.923 for 24 h TS. The results predicted by the RSM are close to the experimental results when the fine particle content (FoC) in the core layer is 39.35 %, the surface particle content (Sf) is 37.45 %, the tube spacing (TD) is 18.81 mm, the MOR of the tubular particle board is 17.47 MPa, the IB is 0.70 MPa, and the 24 h Ts is 7.30 %. The optimized tubular particleboard has a thermal conductivity of 38.89 mW m−1K−1, which provides efficient thermal insulation. The RSM is important in the development and structural optimization field.

Mesostructural Mechanism of Hydraulic Gradient Fluctuations Affecting Internal Instability Using Transparent Soil

Abstract For internally unstable soil, fine particles might migrate in the pore channels of its coarse matrix because of seepage flow, and fluctuations in the hydraulic gradient might promote this migration. To reveal the mechanism for this behavior, simulation testing using transparent soil was employed to visualize the soil mesostructure and particle migration process. Three gap-graded transparent soils with internal stability ranging from unstable to marginally stable and stable were made by mixing different amounts of fine particles. First, comparative seepage tests were conducted on the three soils under steady and fluctuating hydraulic conditions. The effect of hydraulic fluctuations depends on the internal stability of the soil. For the internally unstable or marginally stable soils, hydraulic fluctuations promoted internal instability, whereas for the internally stable soil, small applied hydraulic fluctuations had negligible effects on the measured hydraulic characteristics. Particle bridging during the migration process was used to explain the different behaviors. To verify this concept, a two-stage seepage test was performed, and a three-dimensional digital mesostructural model of the specimen was reconstructed based on continuously scanned images of cross sections. The comparison of the digital models at different stages provided visual evidence of particle bridging. It clearly showed that fine particles bridged at some pore constrictions, and the bridges remained intact during the first steady seepage stage and blocked particle migration paths. During the subsequent fluctuating seepage stage, these particle bridges disappeared, and particle migration resumed.

Influence of process parameters on the formation of inhalable fiber dust during shredding for mechanical recycling of fiber‐reinforced organo sheets

AbstractShredding is a major process step in mechanical recycling, as the plastic scrap needs to be cut into small pieces for further processing. It will be melted and finally injection‐molded to form new plastic parts. Also for fiber‐reinforced thermoplastics, the mechanical recycling process is an ecofriendly process because all resources are reused. One challenge during the shredding of fiber‐reinforced plastics is the fiber dust formation. The fiber dust disturbs the following production processes, and the fiber fragments can be alveolar and thus potentially toxic. Therefore, it is a major aim of this research to optimize the cutting process by investigating the effect of different shredding parameters on the alveolar fiber dust formation. Three different continuous fiber‐reinforced thermoplastic organo sheets (PP with glass fibers, PA6 with glass fibers, PA66 with carbon fibers) are shredded while the parameters of throughput, rotational speed, screen size and feedstock size are varied. The results show no clear effect of the throughput either on the amount of fine particles nor on the number of short fibers after removal of the plastic matrix for all materials. Reducing the screen size in the cutting mill leads to a large increase in the amount of fine particles and on the number of short fiber fragments. Additionally, the rotational speed has a large impact on the amount of fine particles. With increasing rotational speed, the number of fine particles rises, whereas there is no major effect on the fiber length distribution. The investigations relating the rotational speed are valid for all materials, throughput, screen sizes and feedstock sizes. Decreasing the feedstock size leads to an increasing amount of fine particles with no change in fiber length distribution for the glass fiber‐reinforced organo sheets. For the carbon fiber‐reinforced materials, it does not lead to any change in the amount of fiber dust but to an increase in shorter fibers. Thus this parameter seems to be material dependent. Images taken by a scanning electron microscope show alveolar fiber dust fragments in the ground material of all samples.

Study of features of texture and structure evolution during hot rolling in a continuous group of stands of aluminum alloy 6016

The article presents the study results of texture and microstructure evolution during automotive 6016 aluminum alloy hot rolling in the multi-stand continuous hot rolling mill. Optical microscopy, scanning electron microscopy, X-ray structure analysis were applied for examinations. 6016 alloy is noted for specific features of structure and texture formation. The peculiarities are due to the high value of the stacking fault energy and a small amount of intermetallic particles of the second phase. The texture in the form of four incomplete pole figures {111}, {200}, {220} and {311} was investigated by the “reflection” method using a DRON-7 X-ray diffractometer in CoKα radiation. When rolling in a continuous group of stands, the coiling temperature level into a coil is 315 oC at a logarithmic deformation of 2.7 and a deformation rate in the last pass of 70 s-1 is insufficient for complete recrystallization during self-annealing. Annealing the hot rolled coil at 425 oC results in a sharp cubic texture. The amount of fine particles in alloy 6016 is very small; therefore, the main mechanism for suppressing recrystallization is an intense recovery process caused by a high stacking fault energy. The specific features are driven by high stacking fault value and low amount of the second phase intermetallic particles. The obtained data could be useful for thermomechanical treatment processes improvement, crystalline texture evolution modelling and 6ХХХ group alloys improvement.The research was conducted on the expences of the Russian Scientific Fund's grant, the project № 21-19-00548, https://rscf.ru/project/21-19-00548/.

Technology for Producing Fine Tungsten Carbide Powders

The article shows the advantage of electric arc synthesis and subsequent centrifugal spraying of tungsten carbide to obtain a high-quality highly dispersed powder. A tungsten electrode (anode) is fed to the surface of a rotating graphite electrode (cathode) until an electric arc occurs between the electrodes, and the cathode is made in the form of a ring. The angular speed of rotation of the annular graphite electrode is set in accordance with the calculated ratio, which provides fine-dispersed centrifugal atomization of the molten product particles. To prevent intense evaporation of tungsten and the formation of an excessive amount of fine particles, the power of the electric arc for melting the anode is limited to a set value.As a result, the uniformity of the powder increases and the dispersion of the particles of the main fraction decreases.

Sedimentation Behavior of Organic, Inorganic, and Composite Flocculant-Treated Waste Slurry from Construction Works

The disposal of waste slurry from construction engineering is attracting more and more attention due to the thorny issues related to high water content (dewatering is difficult and time-consuming). The use of chemical flocculants is proposed in this study, and organic, inorganic, and composite flocculant are designed to identify the characteristics and efficiency of slurry-water separation. The influence of flocculant type and dosage on slurry settlement and its associated mechanisms are studied by a set of sedimentation column, particle size distribution, and scanning electron microscopy (SEM) tests. The experimental results prove that organic, inorganic, and composite flocculants can promote the efficiency of slurry-water separation, although inorganic flocculants may perform relatively worse in comparison with organic and composite flocculants. The conditioning performance of organic flocculants is sequentially anionic polyacrylamide (APAM) > polyacrylamide (PAM) > amphoteric polyacrylamide (ACPAM) > cationic polyacrylamide (CPAM), while their optimum dosage is 300, 300, 400, and 400 mg/L, respectively. The combined formulation of APAM+FeCl3 improves the conditioning of slurry owing to the charge neutralization, net capturing, and sweeping ability. The flocculating effect causes an aggregation of fine particles, and this induces a decrease in the amount of fine particles and an increase in the fraction of coarse flocs. The SEM results prove that the slurry particles tend to be arranged in a parallel manner and the flocculant induces an agglomeration of fine particles owning to a series of physicochemical reactions. The previous discussions can provide an experimental framework for the development of slurry-water separation technology on waste slurry from construction works.

Effects of particle size and additives on the formation of fine particulate matter during sludge incineration

ABSTRACT With the development of urbanization and industrialization, vast plenty of sewage sludge was produced. Incineration has been becoming the mainstream disposal method due to its many advantages. However, the problem of fine particulate matter produced from the incineration process made a restriction on the development of this method. In this study, the effects of temperature, particle size, and calcium-based additives (CaO) on the generation characteristics and micrographs of fine particulate matter were investigated via a lab-scale fluidized bed. The results revealed that the fine particulate matter showed a bimodal distribution and the two peaks was located at around 0.5 μm and 5 μm, respectively. With the increasing of temperature from 750°C to 950°C, the mass concentration of PM0.5 increased by 12.88 mg/g, while PM5 increased by 57.79 mg/g, which indicated as the temperature increases, the crushing degree of minerals and coke particles is more intense, which further leads to an increase in the amount of fine particles. The number of fine particles increased when the feed size getting smaller, which showed an intense link to the feed size. That was because the smaller the particle size, the more severe the degree of crushing, and the greater the number of fine particles formed after crushing. Furthermore, the results also found that CaO can be used as a good binder between particles to promote the growth and agglomeration of fine particles and inhibit the generation of fine particles. When the additive ratio was 3%, 6%, and 9%, the mass concentration of PM0.3 decreased by 53.7%, 63.5%, and 86.1%, while the mass concentration of PM3 decreased by 43.9%, 74.7%, and 91.7%. Therefore, CaO can be used to reduce the production of fine particles in practical engineering applications.

The influence of the cataclastic matrix on the petrophysical properties of deformation bands in arkosic sandstones

This study investigates how the intensity of the cataclasis deformation mechanism influences petrophysical properties, such as pore diameter, grain size, porosity, and permeability, in deformation bands of arkosic sandstones and conglomerates affected by normal fault zones in the Rio do Peixe Basin, Brazil. We analysed in detail the cataclastic matrix within the deformation bands, defined as the amount of fine particles (<1000 μm) generated by grain crushing that surrounds the coarse particles. We collected data in deformation bands exhibiting different textures such as protocataclastic, cataclastic, and ultracataclastic textures, and we performed structural, microstructural, and petrophysical analyses to establish the geometry, temporal relations, kinematics evolution, and deformation mechanism responsible for the formation and evolution of the deformation bands. Deformation bands evolved progressively with increasing grain comminution, which results in different cataclastic textures within a normal fault zone. These textures influence petrophysical properties, mainly porosity. For example, an increase in the cataclastic matrix generates a decrease in macropores, affecting the pore access. The arkosic and arkosic-lithic sandstones present a more selective intragranular fracturing of feldspar grains than of quartz grains. This fact indicates some degree of mineralogical control on the grain size distribution and porosity. As a result, in the ultracataclastic textures, quartz clasts are relatively well preserved, and feldspar grains are almost completely destroyed. Our study indicates that it is possible to estimate the relative porosity reduction of deformation bands by analysing the amount of cataclastic matrix. These results could greatly influence our understanding of the reservoir properties in faulted arkosic sandstones.

Analysis of damage to structures as a result of soil suffusion

The article presents problems involving the impact of uncontrolled soil moisture on the characteristics of soil ground and, consequently, on the entire building structure. The article investigates problems related to the phenomenon of suffusion. The authors analyzed several characteristic consequences of the phenomenon. All the cases were documented by photographs included in the paper. The authors attempted to analyze the reasons for the current state of all analyzed objects. The task was not easy, because in many of these cases, no detailed documentation was available. It was also not possible to access the geological and soil documentation pertaining to the area of those building structures. The authors attempted to model the phenomenon of suffusion. The results of particle size testing of different soil samples were used for that purpose. The developed suffusion model was verified based on the analysis of the hypothetical soil behavior, containing various amounts of fine particles. It was demonstrated that in many of the analyzed cases, large subsidence of soil ground may occur. In addition, failure mode of the analyzed, hypothetical wall was proposed, assuming that it is exposed to subsidence effected by suffusion. The detailed analysis of internal forces in the wall, carried out for various computational situations, demonstrated that the estimated values of soil subsidence can provide explanation of wall scratches and cracks observed in the analyzed buildings.

Evaluation of conifer and broad-leaved barriers in intercepting particulate matters in a wind tunnel

ABSTRACT Fugitive dust is an important source of particulate matters (PM) emission in the air. Vegetation barriers (VBs) can be an effective way to mitigate PM from fugitive dust sources. It is meaningful to choose appropriate plants to establish VBs that can efficiently capture PM from various sources. This study was conducted to establish comparable and repeatable conditions to evaluate the capability of different VB species in mitigating PM emission from certain fugitive dust source. The airflow around two VBs and their PM interception mechanism was studied in a wind tunnel with simulated PM emission source of animal feeding operations. The species used for the two VBs were conifers represented by Pinus Sylvestris var. mongolica Litv. (PS) and the broad-leaved species represented by Syringa Oblate Lindl. (SOL). The results showed that the interception efficiency of the PS vegetation barrier was only slightly lower than that of SOL vegetation, while the PS had a lower effect on the wind speed at the similar leaf surface area. On the other hand, there were a large number of disordered “ridged” stripes on the microscopic structure of the hydrophilic leaves of SOL and PS, and a large amount of fine particles deposited on the leaves were observed, indicating that the microscopic geometric surface structure increased the deposition efficiency of the particles. These findings help to better understand the potential of tree species to reduce PM in environments. Implications: To evaluate the capability of different VB species in mitigating PM emission from certain fugitive dust source, airflow around the two VBs and their PM interception mechanisms were studied in wind tunnels with comparable and repeatable conditions. The results showed that the interception efficiency of the Pinus Sylvestris var. mongolica Litv. (PS) was only slightly lower than that of the Syringa Oblate Lindl. (SOL) vegetation, while the PS had a lowering effect on the wind speed at the same low leaf surface area. Microscopic analysis of leaves surface indicated that the microscopic characteristics increased the deposition efficiency of the particles.

Experimental investigation on the characteristics of tire wear particles under different non-vehicle operating parameters

Tire wear particles are an important non-exhaust contributor of urban particulate matter, which could cause environmental pollution and threaten human health. In this paper, tire-road rolling wear experiments were carried out using a self-made test rig. The size distribution and generation mechanism of wear particles under different non-vehicle operating parameters (treadwear, road roughness and relative humidity) were investigated. The results show that the size of the tire wear particles is an approximately normal distribution in most cases, and tires with good wear resistance produce fewer particles. The quantity of fine particles (<10 μm) is much higher under water lubricating. Temperature has a strong influence on the particle size and even changes the wear mechanism. The high temperature increases the probability of large particles. Additionally, high temperature produces more tire wear particles and further increases the surface wear during the rapid rise of the tread temperature. The major wear mechanisms of the tire rubber are abrasive wear and fatigue wear, which significantly influence the particle size. Furthermore, this study can provide basic data for the reduction of the secondary hazards of tire wear particles.

Characterization and drying kinetics of iron ore pellet feed and sinter feed

The moisture content of iron ore must be suitable for safe handling and transporting operations. Here, the characterization and drying kinetics of iron ore concentrates were presented and recommendations for the design of dryers were discussed. Pellet feed and sinter feed showed a high amount of fine particles (8–20% dp <10 µm) and a low pore volume (Vpore <10 µm). An ample period for drying at constant rate was observed (critical moisture around 5%), indicating that drying processes aiming at a moderate moisture reduction could be performed within this period. These findings contribute to the design of dryers and support economic operations.

Suitability of recycled concrete aggregates from precast panel buildings deconstructed at expired lifespan for structural use

Abstract This paper presents experimental research conducted to verify the suitability of a specific type of recycled aggregate concrete (RAC) for structural use. The recycled concrete aggregates (RCA) used in the RAC mixtures considered here were obtained from precast panels taken from high-rise buildings, which are typical residential structures in former Eastern Bloc countries of the European continent. Precast panels from these buildings are often considered to be unsuitable sources for structural RAC mainly on account of their poor material base and the low-skilled construction workforce and questionable quality control involved in their production. The scope of testing was determined according to guidelines stated in the EN 206-1 standard. During the execution of the tests, the following characteristics were determined for the RCA: particle size distribution; amount of fine particles; particle density; water absorption; shape index and Los Angeles abrasion resistance. Afterwards, RAC specimens were prepared on the basis of recipes developed in accordance with the EN 12390 standard, and underwent tests which evaluated the following properties: slump; air content; fresh concrete density; compressive strength; flexural strength; hardened concrete density and water absorption. The gained test results show the technical suitability of the tested RCA sources for producing medium strength structural RAC. The obtained RCA water absorption values are relatively high compared to natural aggregate (NA), and the 28-day strengths exhibited by most of the RAC specimens are one class lower than the target values. In spite of these deficiencies, the tested RCA still can be classified as suitable for medium strength structural RAC provided that these predispositions are taken into account during recipe design. The necessity to test the properties of RCA, as soon as its source is taken into consideration, reduces possibilities for general conclusions. Nevertheless, the paper provides concrete manufacturers with practically applicable information for the processing of precast panels from deconstructed buildings, gathering a suitable RCA and the production of structural RAC.

The macroscopic mechanisms and associated atmospheric precursor environmental capacities that lead to secondary fine particle pollution

This paper establishes the kinetic equations in atmospheric chemistry that describe the macroscopic mechanisms of secondary fine particle pollution generated by precursors during atmospheric self-purification. The dynamic and static solutions of these equations can be applied to calculate quantitative relationships between the concentration ratio of precursors and secondary fine particles as well as the physical clearance power of the atmosphere, chemical reaction rate, and the scale of a contaminated area. The dynamic solution presented here therefore corresponds with a theoretical formula for calculating the overall rate constant for the oxidation reaction of reducing pollutants in the actual atmosphere based on their local concentrations and meteorological monitoring data. In addition, the static solution presented in this paper reveals the functional relationship between the concentration of secondary fine particles and precursor emission rate as well as atmospheric self-purification capacity. This result can be applied to determine the atmospheric environmental capacity of a precursor. Hourly records collected over the last 40 years from 378 weather stations in mainland China as well as the spatiotemporal distribution sequence of overall oxidation reaction rates from precursors show that when the reference concentration limit of secondary fine particles is 100 μmol m-3, the atmospheric environmental capacity of total precursors can be calculated as 24890×1010 mol yr-1. Thus, when the annual average concentration limit of given fine particles is 35 μg m-3 and the ratio of sulfate and nitrate to 30% and 20% of the total amount of fine particles, the capacities of SO2, NOx and NH3 are 1255, 1344, and 832 (1010g yr-1), respectively. The clearance density of precursors for different return periods across mainland China under above conditions are also provided in this study.

Expanding particle size distribution and morphology of aluminium-silicon powders for Laser Beam Melting by dry coating with silica nanoparticles

Current requirements for metal powder in Additive Manufacturing via Laser Beam Melting in powder bed (LBM) that ensure repeatably homogeneous thin layers can be spread and LBM products with high relative density ρrel can be built are high sphericity and particle size distributions (PSD) with limited share of fine particles. The most established LBM powder production method today is delicate and costly inert gas atomization. It yields highly spherical particles with continuous particle size distributions, but two thirds of the atomized powder exceed established LBM size ranges. A novel process route to improve flowability of cohesive metal powders is the coating of micro-sized powder particles with small amounts of nanoparticles. In this article, significant improvements in powder layer smoothness and ρrel of LBM samples are shown by statistical analysis of physical experiments on the example of Al-Si powders dry coated with 0.5 wt% nanoparticular fumed silica SiOx. This setup was chosen because Al is most prone to powder flowability issues in LBM and no new chemical elements are added to the alloy from dry coated SiOx. Particle shape is varied from spherical over ovoidal to irregular using powder atomized with Ar, N and air. Effects of variations of PSD and LBM parameters on ρrel, defect types, microstructure and hardness using powders with and without SiOx are investigated. Because ρrel are skewed towards 100%, ANOVA on ranks is the applicable statistical method. Since the principle of using nanoparticles as spacers between microparticles is based on geometry, it is transferrable to other material systems. This may help for example to increase ρrel of LBM metal matrix composites prepared by mechanical alloying as non-spherical particles with considerable amounts of fine particles. The use of larger percentages of atomized powders in LBM can increase resource efficiency.

The Influence of Fine Particle Content (Cement Together with Sand Particles up to 0.25 mm) on Rheological Properties of Concrete Mixture

The influence of the fine particle content on the rheological properties of the fresh concrete mixture was studied. The change of cement together with sand particles up to 0.25 mm in mixture composition was taken into the consideration. The amount of fine particles in mixture composition varied in the range from 402 to 639 kg per one cubic meter of the concrete mixture. Technological properties of the concrete mixture were established according to the standardized requirements, rheological properties: yield stresses and viscosity of conventional concrete mixture were calculated based on analytical formulas. According to obtained test results, the increase of fine particle content from 481 to 520 kg in mixture reduced the yield stresses from about 557 to 132 Pa. Further increase of fine particle content from 600 to 639 kg showed the rise of yield stress by 3.87 times. On the other hand, the viscosity of concrete mixture gradually decreased (ca. 5.6 times). To sum up, the rheological properties of the concrete mixture were significantly influenced by the content, packing density, fineness, surface texture and particle size distribution of fine particles.

Transient unsaturated flow in the drainage layer of a highway: solution and drainage performance

In order to quickly remove water entering pavement layers so as to mitigate water-induced damage, drainage layers are widely used in highway pavements. This paper introduces a 1-D mathematical model in order to quantify the transient behaviour of the groundwater flow in the drainage layer of highway pavements. The model takes into account the capillary effect and the nonlinear relationship between hydraulic conductivity and saturation. The analytical solution is obtained and validated against the 2-D Richards equation-based model. Then, sensitivity analysis is carried out and the results show that the drainage time is reduced and drainage efficiency is enhanced by capillarity. The drainage capacity (the total water drained from the drainage layer) depends on the water retention curve (e.g. αG in the Gardner equation). In view of material selection, a relatively low value of αG helps improve the drainage capacity of the drainage layer, whereas a suitable amount of fine particles also leads to a better drainage performance. Furthermore, the drainage material with hydraulic properties is recommended in terms of drainage performance improvement and strength requirement. The analytical solution, which is simple and easy to use, provides guidance for assessing the capillary effects on the effectiveness and efficiency of subsurface drainage systems of a highway.

Clayey minerals and clayey soils as possible microorganism repositories

Clay minerals are one of the most abundant and crucial structural materials of the Earth’s crust, playing a significant role in many aspects of life. The present study aims to critically investigate the presence of microorganisms within different clayey soil samples. Microorganisms are ubiquitous by nature due to their natural ability to adapt to different habitats. Bacteria and Archea are the most abundant microorganisms in the soil and serve many important roles like nitrogen fixation. Fungi are also an integral part of the soil micro flora as they serve as food sources to other organisms as well as facilitate as layer organisms with beneficial relationships to plants. The continued evolution of man and subsequent use of clayey soils in areas such as pottery, cosmetics, engineering and geophagia brings into question whether microorganisms are harmful. Soil samples with high amounts of fine particles and colloidal substances were studied while taking into account the identified hydrated aluminosilicates and their roles in bioavailability. The study also investigated the possible types of microbial flora associated with each type of clayey soil as well as their functions within the human body. Considering the diverse origin of these microorganisms, we discuss their modes of attachment to clayey soils with the aim of minimising their transmission to humans.