High Clay Content Research Articles

Assessment of phytotoxicity of potable water treatment plant sludge-bound compost pellets on seed germination of radish (Raphanus sativus L.)

Maintenance of compost pellet stability highly depends on the binding materials used. Potable water treatment plant sludge (WTPS) has the potential to be used as a binding material due to its high content of clay, organic matter, and nutrients. Compost and WTPS may contain heavy metals, toxic compounds, salts, and growth inhibitors and they may be phytotoxic to the plants. The present study aimed to assess the phytotoxicity of different pelleted compost using a seed germination bioassay of Raphanus sativus L. Pellet aqueous extracts (PAEs) were prepared from four types of compost pellets (T1: commercial compost pellet, T2: commercial integrated pellet, T3: WTPS-bound compost pellet, T4: WTPS-bound integrated pellet). The dilution sequence of PAEs at 50% and 100% concentrations were tested for seed germination in Petri dishes in a randomized design with three replicates. pH, EC, and selected heavy metal concentrations (Al3+, Zn2+, Cu2+, and Cr6+) were determined in PAEs. Relative Seed Germination % (RSG%), Relative Radicle Growth % (RRG%), and Germination Index (GI) were calculated for all the treatments after 72 hours. RSG%, RRG%, and GI showed negative correlation with EC. PAEs of T2 showed high phytotoxicity, while T4 showed less phytotoxicity at the 100% concentration level, whereas other treatments did not show any signs of phytotoxicity. All the PAEs at 50% concentration level were free from phytotoxicity. Hence, 10% WTPS on a w/w basis can be used as a binding material in pelletizing loose compost.

Modeling of modulus and strength in void-containing clay platelet/cellulose nanocomposites by unit cell approach

Clay platelets/cellulose nanofibril nanocomposites are recyclable engineering materials of interest for sustainable development. There is substantial experimental data for mechanical properties, but modeling efforts are scarce. Here, a conceptual unit cell with voids was used in finite element modeling. Predictions for the in-plane modulus taking voids into account were more accurate than the classical rule of mixtures. Simulations also reveal that the cellulosic matrix undergoes shear and tensile deformation with inclined fracture located near the end of platelets for low clay content while predicting brittle tensile failure for high clay content. The results from the unit cell approach provide improved understanding of experimental observations, supporting the strive to better understand mechanisms of deformation and fracture.

A geospatial assessment of soil properties to identify the potential for crop rotation in rice systems

Crop rotation is one strategy for adapting agroecosystems to a framework that balances ecological diversity, sustainability, and food production. The Sacramento Valley, one of the most productive rice growing regions in the US, faces sustainability challenges including increasing herbicide resistant weed pressure and water use restrictions. Increasing crop diversity may help address these challenges, but this region has unique soil attributes including high clay content, salinity, alkalinity, and cemented subsurface layers, and the degree to which these soil properties influence crop rotation decisions remain unclear. The objectives of this study were to quantify the extent of crop rotation in this region, compare soil properties for rotated and continuous rice fields, and assess the potential for expanding rotations based on the geographic coverage of influential soil variables. Using satellite derived land cover data for 2007–2021, our analysis shows that only ∼5000 ha are in rotation with rice, while 220,000 ha are in continuous rice production. This land cover information is fused with SSURGO soil maps in a spatial random forest model. The modeling approach indicates that fields with soil pH between 6.5 and 8, EC between 0.5 and 2 (ds m-1), and saturated hydraulic conductivity less than 2 (μm s-1) are more likely to be rotated. However, we estimate that only 11% of the continuous rice area has all three of these soil properties combined, suggesting soil limitations are an important constraint. This research highlights a method for evaluating land use decisions in relation to spatial variability of soil properties to better understand barriers to agroecological diversification.

Lithology and Lithofacies Characteristics of Deeply Buried Clastic Reservoirs in Alternating Wet-arid Climate and its Hydrocarbon Significance

There have been series of HPHT (high temperature and high pressure) reservoirs with good quality and high productivity discovered in the Triassic Skagerrak Formation in the Central Graben of the UK North Sea. The bottlenecks for further E&P activity are the complicated depositional facies and high reservoir heterogeneity. The main reservoir space is a mixed porosity network composed of primary pores, micro-pores, secondary pores, secondary micro-pores and micro-fractures. Reservoirs of the Skagerrak Formation have greatly varied lateral connectivity as well as poor vertical connectivity. In the case of sufficiently high pressure differentials, hydrocarbon can be fed from high-potential area to low-potential area. There is no simple linear relationship between depth and reservoir quality. The primary depositional texture (grain size/sorting/clay content, etc.) linked to facies has a fundamental control on reservoir quality. Clean and well sorted cross laminated sandstone has the best reservoir quality, while the reservoir quality of planar laminated sandstone decreased due to increased degree of compaction caused by mica drapes. The reservoir quality of the fine-grained ripple cross laminated sandstone is even poorer than that of the planar laminated sandstone, due to abundant mica and clay drapes. Mottled bioturbated sandstone is fine grained with high clay content, which is more muddy because of containing burrows and insect larva. Pedoturbated sandstone has the poorest reservoir quality due to severe dolomite cementation. The dominant detrital material of the Skagerrak Formation is feldspar that provides abundant secondary porosity by alteration and dissolution. Chlorite coats are commonly developed and stained with residual oil or bitumen, which clearly inhibits quartz cementation and feldspar overgrowth. The presence of these clay coats contributes to the preservation of anomalously high porosity at depth in the cleaner and coarser grained fluvial channel facies. The Skagerrak formation facies is a dryland fluvial-lacustrine depositional system which is controlled by fluctuations of depositional base level due to salt mobilisation. The Skagerrak formation consists of several cycles that are vertically separated by lacustrine mudstone. The reservoir permeability system is composed of active fluvial channel sandstones, terminal splay sandstones, abandoned fluvial channel sandstones, minor channel sandstones connecting fluvial channel and terminal splay, as well as low-permeability faults, while the active fluvial channel sandstone is the “sweet spot”. The analysis of controls on deeply buried reservoir quality is significant to precisely predict “sweet spot” in the Skagerrak Formation.

Salinization and Solonetsization of Soils in River Valleys of the Kulunda Plain

The surface of the Kulunda Plain is dissected by a system of ancient wide valleys, former runoff hollows, which have a very small slope (less than 1°). Rivers flow along these weakly expressed valleys, redistributing readily soluble salts throughout the territory. The regime of these rivers is characterized by a sharp and high flood wave and low (up to complete drying) runoff in the summer. The purpose of this work is to study the ion-salt system of soils of ancient runoff troughs of the Kulunda Plain, groundwater and river waters in order to identify modern processes of soil salinization. During floods, river water feeds close-lying groundwater, influencing its chemical composition. Studies of three key sites in the valleys of the Bagan (Novosibirsk region), Burla and Kulunda (Altai Territory) rivers took place in 2021–2022. Ground waters of varying degrees of mineralization (from 3.4 to 63.0 g/l) and lie close to the surface (2–5 m), which causes a wide distribution of saline hydromorphic soils in the study area. Differences in the salt state of soils in different valleys, groundwater and river waters are discussed. The degree of salinization of soils depended on their granulometric composition. The high content of physical clay contributed to the rise of salts with groundwater and their accumulation in the soil profile. A large amount of exchangeable sodium in the soil absorbing complex of the studied soils (more than 3–5 cm (eq)/kg), the predominance of easily soluble sodium salts in the soil solution with its low mineralization, as well as the alkaline reaction of the soil medium indicates the manifestation of the process of soil salinization.

Reservoir Quality Related to Diagenetic Development in the Carbonate Mishrif Formation: A Case Study from the X Oilfield, Southern Iraq

The Middle Cretaceous Mishrif Formation is considered as the main productive reservoir, southern of Iraq. The rudist-bearing productive zones are characterized by high heterogeneity due to the effects of diagenesis and the depositional environment. The Mishrif Formation represents a carbonate succession which deposited through the Middle Cretaceous (Cenomanian-Early Turonian) within the main retrogressive depositional period succession. This research is identifying the effect of each diagenetic process on the reservoir properties by using the utility of core data and thin sections collaborated with the well logs data along the wells X-46, X-41 and X-42 in the X oilfield. The Mishrif Formation have been subjected into various diagenetic processes such as micritization, neomorphism, dissolution, cementation, dolomitization and pressure solution or stylolitization. Effect of eight diagenetic processes have been recognized in the Mishrif Formation, these processes have affected constructively and destructively on the reservoir quality of the Mishrif Formation; dissolution and fractures have been affected positively, while micritization, cementation, dolomitization, compaction, bioturbation and neomorphism have a negative affect. The porosity logs (Neutron, Density and Sonic) and Gamma ray log are interpreted to find the porosity and clay content to determine the reservoir quality. The porosity results show a wide variation, the primary porosity is decreased in the well X-46 at the depth of 2300-2450 due to the cementation while the secondary porosity is enhanced due to the dissolution and fractures. In well X-42, at the depth of 2225-2400 m there is an increasing in the porosity due to the increasing of grains to clay ratio, while in the X-42 at the middle to the upper parts, the porosity is very low due to cementation, compaction and micritization processes as well as the high content of clay. In general, the porosity is enhanced in the reefal zones due to the geometry nature of the pore throat which increasing both of the effective porosity and permeability.

Major contributions of agricultural management practices to topsoil organic carbon distribution and accumulation in croplands of East China over three decades

Multiple natural and anthropogenic factors jointly drive the spatial distribution of soil organic carbon (SOC) and its dynamics in croplands. Among these factors, agricultural management practices have caused considerable impacts. Previous studies on the driving factors of SOC in croplands have provided significant understanding on this matter. However, whether and how the effects and interplay of these drivers change over time is often unknown, especially agricultural activities. To measure the effects of agricultural management practices on the spatial distribution and temporal change of SOC incorporating the network relationships with other natural drivers at the regional scale, we conducted partial least squares path analysis on the topsoil organic carbon content using two historical soil datasets from cropland samples in East China obtained during the 1980s and the 2010s. Eight indicators and their temporal changes reflecting climate, agricultural management, and edaphic conditions were used to quantify the driving mechanisms of the spatial distribution and temporal change of SOC. The drivers of SOC distribution showed that high SOC was mostly distributed in soils with a relatively low pH and high clay content in warm humid climates. High SOC was associated with the application of N fertilizer, crop residue input, and agricultural machinery in the 1980s and 2010s. The effect of N fertilization on SOC distribution increased from the 1980s to the 2010s, whereas the total edaphic effects significantly decreased from 0.62 to 0.25 (P < 0.01). Regarding the drivers of SOC change over the three decades, the edaphic effects presented the strongest effect (path coefficient of 0.74, P < 0.01), including the negative effects of topsoil acidity and baseline SOC level, as well as the positive effects of total nitrogen (TN) and clay content change. Croplands with lower intensity of management practices in the 1980s generally attained more development in agricultural modernization, which led to a considerable SOC increase. Our research revealed the importance of agricultural management practices on the spatial distribution and temporal change of cropland SOC at the regional scale. The results emphasize the need to measure the changing driving mechanisms of SOC dynamics. The findings indicate that indicators reflecting the effects of agricultural management practices should be included in digital mapping and process-based modeling of soil carbon at different spatiotemporal scales to improve prediction accuracy.

Investigation of thermal and strength characteristics of a natural backfill composite inspired by synergistic biochar–biopolymer amendment of clay loam

Thermally active structures such as crude oil pipelines and high-power voltage cables are usually embedded within local soils for their substructural stability. Based on site requirements, soils are amended with synthetic cementitious materials to improve their strength. However, synthetic binders such as cementation, geo-polymerization, and bio-cementation undermine thermal insulation while improving strength. Moreover, commonly used synthetic binders such as cement and lime are extremely harmful to the geoenvironment due to their hyper-alkalinity and high carbon footprint. Therefore, this study proposes a novel backfill composite consisting of clay loam, biochar, and biopolymer for superior thermal insulation and strength characteristics. Local soil containing high clay content was chosen due to its low thermal conductivity and potential to form stable hydrogen bonding with the biopolymer. The clay loam is amended with 2.5% to 7.5% ( w/ w) biochar and 0.5% to 1.5% ( w/ w) of biopolymer and their various combinations. Out of nine soil–biochar–biopolymer composites devised in the current study, six composites exhibited superior strength and lowered thermal conductivity than the plain soil in both conditions, i.e., optimum moisture state and upon drying. The findings of this study establish the synergistic attributes of biopolymer and biochar amendment for developing a high-strength thermal-insulating soil composite.

Influence of small-scale spatial variability of soil properties on yield formation of winter wheat

BackgroundWith the increasing development of sophisticated precision farming techniques, high-resolution application maps are frequently discussed as a key factor in increasing yield potential. However, yield potential maps based on multiple soil properties measurements are rarely part of current farming practices. Furthermore, small-scale differences in soil properties have not been taken into account.MethodsTo investigate the impact of soil property changes at high resolution on yield, a field trial has been divided into a sampling grid of 42 plots. The soil properties in each plot were determined at three soil depths. Grain yield and yield formation of winter wheat were analyzed at two sites.ResultsMultiple regression analyses of soil properties with yield measures showed that the soil contents of organic carbon, silt, and clay in the top and subsoil explained 45–46% of the variability in grain yield. However, an increasing clay content in the topsoil correlated positively with grain yield and tiller density. In contrast, a higher clay content in the subsoil led to a decrease in grain yield. A cluster analysis of soil texture was deployed to evaluate whether the soil´s small-scale differences caused crucial differences in yield formation. Significant differences in soil organic carbon, yield, and yield formation were observed among clusters in each soil depth.ConclusionThese results show that small-scale lateral and vertical differences in soil properties can strongly impact crop yields and should be considered to improve site-specific cropping techniques further.

Higher microbial C use efficiency in paddy than in adjacent upland soils: evidence from continental scale

Regularly flooded rice paddies usually show greater soil organic C and microbial-derived C contents than adjacent upland counterparts, but the soil microbial physiological traits under these two different land uses spanning regions remain unclear. Here, we collected 40 pairs of adjacent paddy and upland soils from four different climates (mid temperate, warm temperate, subtropics, and tropics) across eastern China to determine the microbial growth, respiration, and C use efficiency using the 18O-H2O incubation method. Upland soils from warmer climates exhibited lower microbial growth but higher respiration normalized to microbial biomass C (qGrowth and qRespiration, respectively) than those from cooler climates, since the lower soil pH and higher clay content in warmer climates induced a shift from microbial growth to respiration. Whereas, paddy soils from warmer climates had consistently lower qGrowth and qRespiration than cooler climates, probably due to the long term water-logged condition decreased the sensitivity of microbial metabolism in response to lower pH. Paddy soils had higher qGrowth, but lower qRespiration than upland soils, resulting in a greater C use efficiency regardless of climate zones. The difference in microbial C use efficiency between paddy and upland soils was positively correlated to their difference in soil organic C content. From the perspective of microbial C metabolism, the greater organic C accumulation in paddy than that in upland soils is attributed to the weaker microbial uptake of organic C and stronger microbial anabolism under the water-logged condition.

The role of clay minerals in the preservation of Precambrian organic-walled microfossils.

Precambrian organic-walled microfossils (OWMs) are primarily preserved in mudstones and shales that are low in total organic carbon (TOC). Recent work suggests that high TOC may hinder OWM preservation, perhaps because it interferes with chemical interactions involving certain clay minerals that inhibit the decay of microorganisms. To test if clay mineralogy controls OWM preservation, and if TOC moderates the effect of clay minerals, we compared OWM preservational quality (measured by pitting on fossil surfaces and the deterioration of wall margins) to TOC, total clay, and specific clay mineral concentrations in 78 shale samples from 11 lithologic units ranging in age from ca. 1650 to 650 million years ago. We found that the probability of finding well-preserved microfossils positively correlates with total clay concentrations and confirmed that it negatively correlates with TOC concentrations. However, we found no evidence that TOC influences the effect of clay mineral concentrations on OWM preservation, supporting an independent role of both factors on preservation. Within the total clay fraction, well-preserved microfossils are more likely to occur in shales with high illite concentrations and low berthierine/chamosite concentrations; however, the magnitude of their effect on preservation is small. Therefore, there is little evidence that bulk clay chemistry is important in OWM preservation. Instead, we propose that OWM preservation is largely regulated by physical properties that isolate organic remains from microbial degradation such as food scarcity (low TOC) and low sediment permeability (high total clay content): low TOC increases the diffusive distances between potential carbon sources and heterotrophic microbes (or their degradative enzymes), while high clay concentrations reduce sediment pore space, thereby limiting the diffusion of oxidants and degradative enzymes to the sites of decay.

Grain-Level Numerical Simulations for the Effective Elasticity of Weakly Cemented Sandstones.

Weakly cemented sandstones are characteristic of loose-bonding contacts, large porosities, and high-clay contents. This study presents a discrete element method (DEM)-based numerical study for the effective elasticity of such rocks that mainly depends on the mechanical behavior of intergranular contact regions. The DEM scheme employs a set of normal and shear springs to phenomenologically describe the mechanical behavior of intergranular finite-sized cements defined by three morphological parameters: cement thickness, bonding radius, and grain radius. Applications to two digital models established in terms of contact-bonding and distant-bonding modes, respectively, where spherical quartz grains are randomly packed together with adding cements under the specified confining pressure, are compared with the theoretical predictions by the contact-bonding and distant-bonding cement theories, which demonstrates a good agreement generally for small contact widths, small contact thicknesses, and large-magnitude moduli, especially for the effective shear modulus. Applications to a series of artificial sandstone samples made in terms of different proportions of quartz grains and clays (a mixture of epoxy and kaolinite) under loose compaction for weak cementation demonstrate a good agreement with ultrasonic measurements. Numerical investigations for the micromechanical characteristics (differential stress fields, force chains, and fabric tensors) of artificial samples subject to applied axial strains demonstrate that the strong mechanical behavior of weakly cemented sandstones tends to appear inside the cohesive aggregates of stiff grains because of their relatively large sizes with loose compaction.

Effects of organic carbon and clay contents on structure‐related properties of arable soils with high clay content

AbstractUnderstanding of factors governing soil structural features is necessary for managing key processes affecting crop productivity and environmental impacts of agriculture, for example, soil water balance, aeration, and root penetration. Organic matter is known to act as a major binding agent in soil aggregation and thus constitutes a central pillar in soil structure formation. However, knowledge of the structural role of organic matter or carbon (OC) in soils highly rich in clay‐sized particles (&lt;0.002 mm) is limited. In this study, the effects of clay and OC contents on aggregate stability, water holding capacity, near‐saturated hydraulic conductivity, total porosity, and pore size distribution were assessed in cultivated fields with high clay content located in private crop production farms in southern Finland. Significant positive correlations were found between OC content and proportion of water stable aggregates and specific pore sizes from the range of 30 μm up to 1 mm diameter determined by image analysis. Porosities on a smaller size range derived from water retention measurements likewise showed a positive correlation with OC in &lt;0.2 μm sizes. On the range of 0.2–1 μm, a negative relationship was observed, which induced a negative effect of OC on soil plant available water reserves. In line with the positive correlation between OC and larger soil pores, free water, representing the amount of water that can be drained by gravity, exhibited a positive relationship with OC suggesting that OC content can enhance aeration of soils with high clay content. Compared to OC, clay content tended to have an adverse effect on soil structural properties. Clay correlated negatively with pores larger than 30 μm, free water content, and extrapolated field saturated hydraulic conductivity. Further, our imaging results showed how saturated hydraulic conductivity was controlled by pore morphology, and there was a power law relationship between the conductivity and critical pore diameter. in agreement with the percolation theory. Overall, the structural impacts and hydrological implications of OC and clay in heavy clay soils vary by pore size ranges and their emergent practical impacts are thus not straightforward.

Permeability of High Clay Content Dredger Fill Treated by Step Vacuum Preloading: Pore Distribution Analysis

In this study, the step vacuum preloading method was used to reinforce high clay content dredger fill in the laboratory. The pore structures and permeability characteristics of dredger fill under different vacuum pressures were tested. The correlation between the pore structure parameters and permeability coefficient was analyzed using the grey T’s correlation analysis method. The research results indicate that the pore ratio, large pore (the diameter with a range of 4–40 μm) content, and permeability coefficient of dredger fill decreased with the increase in vacuum pressures, but the decrease rates of the pore ratio were different at various sampling locations. The contents of micropores (the diameter with a range of &lt;0.04 μm) and small pores (the diameter with a range of 0.04–0.4 μm) increased with the increase in vacuum pressure. The results of the correlation analysis showed that a large pore content had a strong correlation with the permeability coefficient and could be used to describe the permeability characteristics of soil. The research results can provide reference for the improvement of the reinforcement method and for the evaluation of the reinforcement effect of dredger fill in engineering practice.

Factors driving PPCPs uptake by crops after wastewater irrigation and human health implications

Currently, water scarcity affects more than three billion people. Nevertheless, the volume of treated wastewater discharged into the environment is estimated to exceed 100 m3 per inhabitant/year. These water resources are regularly used in agriculture worldwide to overcome water shortages. Such a practice, however, entails the uptake of waterborne pollutants, such as pharmaceuticals and personal care products (PPCPs), by crops and their further access to the food web, constituting an additional route of human exposure to PPCPs, with potential health outcomes.In this study, the occurrence of 56 PPCPs in tomatoes, lettuce, and carrot, together with soil and irrigation water, was evaluated using a QuEChERS-based methodology for extraction and LC-MS/MS for analysis. The influence of the selected cultivation conditions on the plant uptake levels of PPCPs was assessed. Two irrigation water qualities (secondary and tertiary treatment effluents), two soil compositions (sandy and clayey), two irrigation systems (dripping and sprinkling), and three crop types (lettuce, tomato, and carrot) were tested. Carrots showed the highest load of PPCPs (7787 ng/g dw), followed by tomatoes (1692 ng/g dw) and lettuces (1248 ng/g dw). The most translocated PPCPs were norfluoxetine (fluoxetine antidepressant main metabolite) (521 ng/g dw), and the anti-inflammatory diclofenac (360 ng/g dw). Nine PPCPs, are reported to be accumulated in crops for the first time. Water quality was the most important factor for reducing PPCPs' plant uptake. Overall, the best conditions for reducing PPCP uptake by crops were irrigation with reclaimed water by sprinkling in soils with higher clay content. The risk assessment performed revealed that the crops' consumption posed no risk to human health. This study serves as the first comprehensive assessment of the relevance of diverse cultivation factors on PPCPs’ plant uptake under field agricultural practices.

Calibration procedure of Discrete Element Method (DEM) parameters for wet and sticky bulk materials

The downtimes associated with blockage events in the materials handling sector have prompted the mining industry to optimise its operations to maximise the profitability of fines and lump products. These blockage events are caused by materials with a high clay or moisture content typically referred to as Wet and Sticky Material (WSM). Numerous methods are commonly used to prevent such blockage events, however, in the majority of cases, they are often too late to prevent the downtime of the system. The Discrete Element Method (DEM) is commonly used to predict and visualise the bulk material flow. DEM is capable of replicating the flow of non-cohesive granular materials with reasonable accuracy, however, when cohesive materials are considered the mechanism becomes much more complex. With the advancement of computational power over the last few decades, it is now more practical to simulate WSMs into DEM.This paper evaluates the capability of three cohesion models to simulate WSMs; the Simplified Johnson-Kendall-Roberts (SJKR) model, the Easo Liquid Bridging model and the Edinburgh Elasto-Plastic Adhesion (EEPA) model. A calibration procedure is proposed where the parameters for each cohesion model are discussed in detail. A series of calibration simulations with systematic parameter variation is undertaken to define a set of calibration matrices. These matrices allow the formation of a parameter database, used for the simulation of on-site applications to optimise plant geometry and other operational parameters. Finally, the numerical model was validated using a lab-scale vertical impact testing facility. Individually, in a transfer chute application, it was determined that none of the 3 cohesion models were suited to WSMs; the SJKR and Easo liquid bridging models were unable to replicate the behaviour, and while the EEPA model was able to replicate the behaviour, extensive solve times deemed it impractical for industrial applications. These limitations were overcome through the coupling of the SJKR and Easo Liquid Bridging models.

Experimental study on composite flocculant-electroosmosis combined with segmented solidification treatment of high-water-content slurry

To address the challenges related to high drainage efficiency, energy consumption, and turbidity in traditional electroosmosis methods, particularly for mud with ultra-high water content and high clay content, this study proposes a novel research approach: the combined flocculant-electroosmosis combined with segmented solidification treatment of high-water-content slurry.This study explores the mechanism of action and drainage effect of the composite flocculant-electroosmotic method using a self-developed one-dimensional electroosmosis test device. The test results show that there is an optimal ratio of organic flocculant (anionic polyacrylamide,APAM) and inorganic flocculant (polymeric aluminum chloride,PAC,and anhydrous calcium chloride,CaCl2) combined with the composite flocculant.Compared with the traditional single flocculant-electroosmosis method, the drainage volume of the composite flocculant-electroosmotic combined method is increased by an average of 73.76%. Although the total electroosmotic energy consumption and anode corrosion of the composite flocculant group have increased, the average electroosmotic energy consumption coefficient and anode corrosion coefficient are higher, indicating that the energy consumption coefficient is better than that of the traditional electroosmotic group. Innovatively, segmental solidification was carried out based on the anode corrosion cracks and sudden changes in water content after the completion of electro-osmosis, which yielded excellent reinforcement effects and met the requirements of external transportation and reuse.

A rock physics model in vertical transverse isotropy media and its application to Eagle Ford shale

AbstractShales are rocks with a complex structure. Shales contain high clay content, which constitutes a load‐bearing skeleton. In this study, we present a novel rock physics model to obtain elastic stiffness coefficients of both clays and shales. The robustness of the model is then verified by a field dataset from Eagle Ford shale. We utilize the extended Maxwell homogenization scheme as a rock physics model for transversely isotropic media, which honours the aspect ratio of each inhomogeneity embedded in an effective inclusion domain. Estimated anisotropy parameters ε, γ and δ, on average, are 0.19, 0.29 and 0.04, respectively, based on our modelling results in Eagle Ford shale. Anisotropic modelling results exhibit a good correlation with dipole sonic logs. Both dipole sonic log analysis and rock physics results demonstrate that clay content is the main driver of anisotropy in the field, and there is a direct relationship between clay volume and anisotropy parameters of ε and γ. The method shown here can be readily applied to other unconventional reservoirs.

The Leaching of Palladium from Polymetallic Oxide Ores using Alkaline Ferricyanide Solutions

ABSTRACT The present study investigated a novel method of alkaline ferricyanide leaching to extract palladium (Pd) from a Western Australian disseminated platinum-group metal (PGM) oxide ore that bears Ni and Cu. While cyanide has been used to leach Pd, it is well known for its toxicity and large consumption in the presence of base metals. A more benign alternative, in the form of alkaline ferricyanide, is evaluated in this research to serve the combined role of lixiviant and oxidant. Various leaching parameters, such as ferricyanide concentration (1–30 g/L), dissolved oxygen level (up to 25 ppm), pH (10–12), and temperature (20–80°C), were investigated to evaluate Pd extraction. The Pd extraction was found to be the most sensitive to leach temperature with Pd extraction doubling when the temperature was raised from 20°C to 80°C. The highest Pd extraction of 76.1% was achieved at 10 g/L ferricyanide, pH 11, DO 15 ppm, 80°C, and 10% solids. The alkaline ferricyanide leaching system showed high selectivity for Pd over other metals (Pt, Co, Ni, Cu). The co-extractions of base metals (Co, Cu, and Ni) were all below 2%, and that of Pt was below 10% over the range of temperatures investigated. Although conventional cyanidation at a low cyanide consumption (1 kg/t) showed slightly better performance in Pd extraction, the ferricyanide leaching significantly improved the settleability and filterability of the leaching slurry considering the finely ground nature and high-clay content of the lateritic oxide ores. In contrast, the cyanidation leaching slurry was found to filter or settle poorly.

Stabilisasi Tanah Ekspansif Menggunakan Limestones Sebagai Subgrade Perkerasan Jalan Pada Proyek Jalan Tol Seksi 6a Paket Sumedang – Dawuan

The problems that occur in the Toll Road Project Section 6a of the Sumedang – Dawuan package are subgrade soils including expansive soil types. Where the type of expansive soil is a soil type that is not good with very high clay content, expansion and shrinkage. This potential for shrinkage causes less stability in the road construction so that it affects the safety and comfort of traffic. The general technical properties of expansive soils are that they have a fairly high moisture content and low bearing capacity. Because of these properties, expansive soils are classified as poor soils to be used as subgrades. One way to overcome this is by improving the soil or so-called soil stabilization. In this study, the material used for stabilizing the expansive soil is limestone. Limestone or limestone is a carbonate rock that is formed biologically and biochemically.This research was conducted with the aim of knowing the effect of adding limestone to the physical properties of expansive clay and knowing the optimum level of addition of limestone so as to produce a maximum increase in the stability of the road construction subgrade. The research method used is the experimental method. The study was designed with 5 treatments, namely 0%, 25%, 50%, 75% and 100% of the use of limestone on expansive clay soil.The results showed that the use of limestone as a stabilizing agent for clay in the Section 6a of the Sumedang – Dawuan Toll Road Project affects the physical and mechanical properties of the expansive clay. Where the higher the addition of limestone, the smaller the liquid limit (LL), plasticity limit (PL), moisture content and swelling, while for specific gravity, compaction and CBR the higher. The use of limestone in the Toll Road Project Section 6a Sumedang – Dawuan Package optimum 75% with a ratio of 25% expansive clay with a CBR value of 3.75% &lt; 6% (Minimum requirement of CBR value for road pavement subgrade) and produces a development value ( swelling) 3.85% &gt; 1.25% (maximum limit conditions for pavement subgrade swelling). The CBR value and swelling (swelling) do not meet the requirements as a subgrade for road pavement, in accordance with the expressway technical specifications for a minimum subgrade density of 100℅, a minimum CBR of 6℅ and a maximum swelling of 1.25℅.