Heavy Carbonate Research Articles

Immobilization of Cadmium Via Ureolytic Bacteria Isolated from Greywater Waste and Horse Faeces

With the constant growth of technology and pollution caused by urban expansion, heavy metal contamination has become an alarming concern. The performance of Microbial induced carbonate precipitation technology in immobilizing heavy metal has been demonstrated by several researchers. While various studies have successfully isolated ureolytic bacteria from a variety of sources, there are very limited studies that have focused on isolating them from local waste sources, specifically Greywater and Horse Faeces for MICP application, which benefits in terms of economical, sustainability, and efficiency for engineering purposes. The study aims to investigate the effect of urease-producing bacteria derived from Greywater and horse faeces on heavy metal immobilization. The methods include collecting waste samples, isolating and subculturing of ureolytic bacteria, testing the physiological characteristics of ureolytic bacteria, examining the tolerance test and evaluating heavy metal removal efficacy through Atomic Absorption Spectrophotometry (AAS) analysis, and last but not least, Scanning Electron Microscopy (SEM) and Energy-Dispersive X-ray (EDX) analyses of morphological and mineralogical properties of biominerals formed after heavy metal immobilization treatment. The study found that bacteria from Greywater were more effective at heavy metal immobilization than those from Horse Faeces. Additionally, AAS analysis indicates the greywater-derived bacteria from the residential area sample's exceptional competence in Cd2+ removal, with a significant 80.19% removal rate exceeding the horse faeces bacteria sample's removal rate of 65.26%. The morphological analysis confirmed the presence of heavy metal carbonate in treated heavy metal samples, as well as presenting insight into the effectiveness and application of local ureolytic bacteria's potential for heavy metal toxicity degradation.

In situ combustion performance in heavy oil carbonate reservoirs: A triple-porosity numerical model

This study aims to address the challenges of oil recovery in highly heterogeneous carbonate reservoirs by employing a novel triple-porosity numerical model approach for in-situ combustion (ISC). The primary focus is on the performance of ISC within isolated vuggy pore spaces, a characteristic feature of such reservoirs. By simulating triple-porosity through artificially induced vuggs, core matrix, and fractures, we evaluated the feasibility of the ISC technique for heavy oil recovery in a dolomite reservoir using a combustion tube setup.The numerical model, calibrated through history matching, incorporates an extended kinetic reaction scheme to better represent high-temperature oxidation processes. Experimental and simulation results show a strong correlation in temperature profiles, ignition timing, and fluid production, effectively reproducing the observed gas compositions. This integrated experimental and numerical approach demonstrates the potential for applying ISC in triple-porosity systems, offering valuable insights for field-scale implementations in similarly complex carbonate reservoirs. The novelty of this research lies in its comprehensive modeling of the first ISC experiment in a triple-porosity framework, providing a deeper understanding of the interactions between matrix, fracture, and vugg networks, and paving the way for enhanced oil recovery (EOR) strategies in challenging reservoir environments.

Significantly improved sintering shrinkage of heavy calcium carbonate ceramic cores by binder jetting using Al powder additive

In this study, the ceramic cores were printed with heavy calcium carbonate (HCC, CaMg(CO3)2) powder as raw material and Al powder as additive by binder jetting (BJ). The ceramic cores were impregnated with nano-ZrO2 dispersion solution and then sintered at high temperature to prepare the ceramic cores with low sintering shrinkage. The effects of different Al powder contents (20 wt%∼40 wt%) on the properties and sintering shrinkage of the ceramic cores were studied. It was found that with the increase of Al powder content (20 wt%∼40 wt%), the bending strength of the ceramic core gradually decreased from 35.82 MPa to 11.89 MPa, and the porosity continuously increased from 8.94 % to 46.4 %. The sintering shrinkage rate of the ceramic core also gradually decreased, and even slightly expanded. This is because the oxidation of the Al powder to Al2O3 produced a large volume expansion, and the Al2O3 reacted with the CaO and MgO generated by the decomposition of HCC to produce calcium hexaluminate (CA6), calcium dialuminate (CA2), MgAl2O4 (MA) and other substances, and these reaction processes also produced a certain volume expansion. When the amount of the Al powder was 40 %, the dimensional change rates of X, Y and Z axis of the ceramic core were 2.48 %, 2.35 % and −0.6 %, respectively. Compared with the ceramic core without Al powder, the sintering shrinkage rate decreased by 91.2 %, and the dimensional accuracy of the ceramic core was improved significantly. By observing the microstructure of the ceramic cores, it is found that various substances inside the ceramic core formed a network distribution structure, which achieved a good toughening effect and ensured that the ceramic core had a good bending strength under large porosity.

Development and application of artificial hydraulic lime for Chinese architectural heritage restorations

Lime is commonly employed in the restoration of historic buildings due to its strength properties, which align well with the demands of architectural heritage conservation. However, recent shortages in high-quality limestone raw materials and the commercial inclusion of finely ground limestone powder in hydrated lime powder have led to significant challenges. These include low initial strength, pronounced shrinkage and cracking, and poor resistance to frost. Although natural hydraulic lime (NHL) offers moderate strength, its high cost presents an obstacle to widespread use in architectural heritage restoration. Three types of artificial hydraulic lime (AHL) — AHL1, AHL2, and AHL3 — were prepared with the objective of low cost and easy scalability. These were formulated by incorporating white cement (WC), blast furnace slag powder (BFSP), heavy calcium carbonate powder (HCCP), and industrial-grade white sugar (WS) into industrial-grade hydrated lime powder (IHLP). To align the setting time of the AHLs with the requirements of traditional builders, WS was incorporated as a retarding agent. The addition of WC, BFSP, and HCCP to IHLP resulted in enhancements over IHLP in several key aspects: compressive strength, pore structure post-hardening, dry shrinkage rate, and frost resistance. This approach will enhance the restoration quality of architectural heritage in China, leading to fewer repeated repairs and significant savings in manpower and material costs. Ultimately, AHL2 was applied in the restoration of the Confucius Temple, proving its efficacy and alignment with traditional construction requirements. This research provides valuable theoretical and practical insights for enhancing the preservation of architectural heritage.

An Enzyme-Induced Carbonate Precipitation Method for Zn2+, Ni2+, and Cr(VI) Remediation: An Experimental and Simulation Study

Heavy metal contamination has long been a tough challenge. Recently, enzyme-induced carbonate precipitation (EICP) has been proposed to handle this problem. This paper aims to explore the efficacy, process, and mechanisms of EICP using crude sword bean urease extracts to remediate Zn2+, Ni2+, and Cr(VI) contamination. A series of liquid batch tests and geochemical simulations, as well as microscopic analyses, were conducted. The liquid batch test results show that Zn2+, Ni2+, and Cr(VI) can be effectively immobilized by the EICP method, and the highest immobilization percentage was observed for Zn2+, reaching up to 99%. Ni2+ and Cr(VI) were immobilized at 62.4% and 24.4%, respectively. Additionally, the immobilization percentage of heavy metals increased with the concentration of added Ca2+. The simulation results and XRD results reveal that the organic molecules in crude sword bean urease can promote ZnCO3, Zn(OH)2, Zn5(CO3)2(OH)6, and NiCO3 precipitation. The FTIR and SEM-EDS results provide evidence for heavy metal adsorption by the functional groups in crude urease and calcium carbonate. The liquid batch test results, as well as the simulation results and the microscopic analysis results, indicate that the mechanism of EICP in heavy metal remediation can be summarized as biomineralization to form heavy metal carbonate precipitates and metal hydroxide precipitates, adsorption by calcium carbonate, and adsorption or complexation or promoting nucleation by organic molecules.

Enhancing Hydraulic Lime Mortar with Metakaolin: A Study on Improving Restoration Materials for Historic Buildings.

This study investigates the enhancement of hydraulic lime mortar (HLM) using varying contents of metakaolin (MK) to improve its application in the restoration of historic buildings. Samples from historic structures were analyzed, and the effects of different MK contents on the physical and mechanical properties of HLM were examined. The reaction mechanism and microstructural changes were evaluated using XRD and SEM analysis. The results indicated that increasing MK levels in HLM led to a decrease in fluidity, with fluidity reducing by 4.8% at 12% MK. The addition of MK increased water consumption for standard consistency by 5.4% and shortened the final setting time by 10.2%. MK consumption promoted secondary hydration, enhancing compressive strength by up to 98.1% and flexural strength by up to 55.1%, and increasing bonding strength by 26.9%. The density of HLM improved with MK addition, slightly reducing moisture content by 4.5% and water absorption by 4.6%, while the water vapor transmission properties decreased by 50.9%, indicating reduced porosity. The elastic modulus of the mortar increased significantly from 2.19 GPa to 7.88 GPa with the addition of MK, enhancing rigidity and crack resistance. The optimal blend for restoration materials was found to be 9.0% MK and 25.0% heavy calcium carbonate and was characterized by moderate mechanical strength, enhanced early strength, commendable permeability, minimal risk of cracking, and ease of application. This blend is highly suitable for the rehabilitation of historic structures.

Exploring in-situ combustion effects on reservoir properties of heavy oil carbonate reservoir

Laboratory modeling of in-situ combustion is crucial for understanding the potential success of field trials in thermal enhanced oil recovery (EOR) and is a vital precursor to scaling the technology for field applications. The high combustion temperatures, reaching up to 480 °C, induce significant petrophysical alterations of the rock, an often overlooked aspect in thermal EOR projects. Quantifying these changes is essential for potentially repurposing thermally treated, depleted reservoirs for CO2 storage.In this study, we depart from conventional combustion experiments that use crushed core, opting instead to analyze the thermal effects on reservoir properties of carbonate rocks using consolidated samples. This technique maintains the intrinsic porosity and permeability, revealing combustion's impact on porosity and mineralogical alterations, with a comparative analysis of these properties pre- and post-combustion. We characterize porosity and pore geometry evolution using low-field nuclear magnetic resonance, X-ray micro-computed tomography, and low-temperature nitrogen adsorption. Mineral composition of the rock and grain-pore scale alterations are analyzed by scanning electron microscopy and X-ray diffraction.The analysis shows a significant increase in carbonate rocks’ porosity, pore size and mineral alterations, and a transition from mixed-wet to a strongly water-wet state. Total porosity of rock samples increased in average for 15%–20%, and formation of new pores is registered at the scale of 1–30 μm size. High-temperature exposure results in the calcite and dolomite decomposition, calcite dissolution and formation of new minerals—anhydrite and fluorite. Increased microporosity and the shift to strongly water-wet rock state improve the prospects for capillary and residual CO2 trapping with greater capacity. Consequently, these findings highlight the importance of laboratory in-situ combustion modeling on consolidated rock over tests that use crushed core, and indicate that depleted combustion stimulated reservoirs may prove to be viable candidates for CO2 storage.

Red mud modified phosphogypsum based self-leveling mortar: Hydration mechanism, heavy metal migration law and spatial distribution characteristics

In the production processes of phosphoric acid and alumina, chemical enterprises generate solid waste such as red mud (RM), phosphogypsum (PG), and fly ash (FA). The environmentally friendly utilization of these waste materials is of crucial significance. Therefore, this study focuses on investigating the impact of collaborative modification using diverse solid wastes on the macroscopic properties and internal microstructure of self-leveling mortar. Through a careful selection process, the optimal ratio for red mud and phosphogypsum self-leveling mortar(RPSM) has been identified during the research. This study not only provides substantial support for the effective utilization of solid waste but also contributes to the improvement of overall performance and structural characteristics of the mortar. Based on this, the hydration characteristics, leaching patterns, and spatial distribution characteristics of heavy metals in RPSM were evaluated. The research revealed that the optimal ratios of RM, PG, FA, PC, river sand, and heavy calcium carbonate powder in RPSM were 20.7%, 13.8%, 17.1%, 13.8%, 17.3%, and 17.3%, respectively. Under a water-binder ratio of 0.18, the flexural and compressive strength of the mortar specimens after 14 d of curing can reach 4.3 and 31.6 MPa. Through comprehensive analysis and discussion of the performance, microstructure, and dynamics of the hydration process of RPSM, the main processes of mortar hydration were elucidated. Environmental risk assessments indicated no environmental risks from heavy metals in RPSM. Human health risk assessment suggested carcinogenic risks from Cr and Cd in RPSM through oral exposure, leading to restrictions on the content of characteristic heavy metals in different application scenarios. Furthermore, fitting results of the release kinetics of heavy metals indicated that the leaching of heavy metals in RPSM can be well fitted with kinetic models, allowing the determination of the optimal safe age of RPSM containing harmful heavy metals. Finally, using interpolation and vertical distribution simulation by software such as ArcGIS, the spatial distribution characteristics of heavy metals in RPSM during use were analyzed. The research can supply fundamental academic support for the recycling of solid wastes like RM and the control of environmental risks associated with heavy metal leaching in building materials.

Hydroxyl silicone oil grafting onto a rough thermoplastic polyurethane surface created durable super-hydrophobicity

Indwelling medical catheters are frequently utilized in medical procedures, but they are highly susceptible to infection, posing a vital challenge for both health workers and patients. In this study, the superhydrophobic micro-nanostructure surface was constructed on the surface of thermoplastic polyurethane (TPU) membrane using heavy calcium carbonate (CaCO3) template. To decrease the surface free energy, hydroxyl silicone oil was grafted onto the surface, forming a super-hydrophobic surface. The water contact angle (WCA) increased from 91.1° to 143 ± 3° when the concentration of heavy calcium CaCO3 was 20% (weight-to-volume (w/v)). However, the increased WCA was unstable and tended to decrease over time. After grafting hydroxyl silicone oil, the WCA rose to 152.05 ± 1.62° and remained consistently high for a period of 30 min. Attenuated total reflection infrared spectroscopy (ATR-FTIR) analysis revealed a chemical crosslinking between silicone oil and the surface of TPU. Furthermore, Scanning electron microscope (SEM) image showed the presence of numerous nanoparticles on the micro surface. Atomic force microscope (AFM) testing indicated a significant improvement in surface roughness. This method of creating a hydrophobic surface demonstrated several advantages, including resistance to cell, bacterial, protein, and platelet adhesion and good biosecurity. Therefore, it holds promising potential for application in the development of TPU-based medical catheters with antibacterial properties.

Study on Proportioning Scheme of Coal System Rocky Similar Material Based on Orthogonal Test.

Similar materials play an important role in model testing. In order to meet the demand for similar materials in modeling tests, such as those on coal mining, coal system rocky similar materials were formulated using yellow sand as a coarse aggregate, heavy calcium carbonate as a fine aggregate, and cement and gypsum as binders. Based on the orthogonal experimental design method, four influencing factors, namely the aggregate-binder ratio, heavy calcium carbonate content, cement-gypsum ratio, and moisture content, were selected. Each factor was designed at five levels. Through weighing, uniaxial compression, Brazilian splitting, and variable-angle plate shear tests on 225 specimens under 25 different ratios, five physico-mechanical property indicators of the material, including density, compressive strength, tensile strength, cohesion, and internal friction angle, were obtained under different ratios. The test results indicate that the similar materials formulated with the above raw materials had a wide range of mechanical properties, which met the simulation needs of different types of coal rocks, such as main coking coal, anthracite, shale, etc., in the similar model test. Range analysis was adopted to analyze the sensitivities to each factor, which showed that the density and internal friction angle of similar materials are mainly controlled by the aggregate-binder ratio; the cement-gypsum ratio mainly controls the compressive strength, tensile strength, and cohesion of the material. Analysis of variance (ANOVA) was adopted to analyze the sensitivities to each factor, which showed that the aggregate-binder ratio had a highly significant effect on the density of the material, the cement-gypsum ratio had a highly significant effect on the compressive and tensile strength of the material, the cement-gypsum ratio had a significant effect on the cohesion and density of the material, and the moisture content had a significant effect on the compressive strength of the material. The remaining factors did not significantly affect the material parameters. The results of this study can provide some reference for the selection of coal system rocky similar materials in subsequent physical modeling tests.

Detection and Characterization of Active Microbial Cells in Salt Cavern Brine

Salt caverns have been used for decades as natural gas storage facilities and are now target of large-scale underground H2 storage to secure national energy transition goals. Contrary to CH4, H2 is a universal electron donor for microbial anaerobic respiration. Suitable electron acceptors are sulfate and carbonate, which dissolve from gypsum, anhydrite and lime that can make up 10 % of subsurface salt formations. Whilst sulfate reduction is inherently linked to the formation of H2S, microbial CO2 reduction can generate acetate, which can be used as carbon source by diverse microorganisms. Thus, supporting other microbial side effects, such as H2S formation, clogging and H2 consumption. However, microbial diversity and activity in salt caverns are selectively controlled by salt concentrations close to saturation and limited availability of organic carbon. If these conditions allow for microbial activity was investigated in our study. To circumvent long enrichment times associated with high salinity and limited nutrient availability, we used a stable isotope labelling approach combined with nano-scale secondary ion mass spectrometry analysis (SIP-nanoSIMS) to investigate H2-dependant microbial activity in two brine samples and compared them with that of an extremely halophilic enrichment culture (MP-32). Heavy carbonate and water (13CO2 and 2H2O) served as tracers for microbial activity. Microbial H2 consumption was additionally investigated in microcosm experiments with brine and rock salt over a period of 200 days. Setups with MP-32 served as a positive control. Subsequently, MP-32 was selected for metagenome sequencing to explore potential metabolic pathways and strategies for osmoadaptation. Analysis of the microbial community composition in brine revealed that members of the Desulfohalobiaceae, Halobacteria and Halanaerobiales were present in all caverns and their relative abundance increased during incubation with H2 as electron donor although sulfate reduction was not observed. But incubation with H2 resulted in an increased uptake of 13C from 13CO2 in 1.6 to 3.6 % of the cells compared to incubations without H2. Uptake of 2H from 2H2O was detected in 20 to 30 % of the cells and was higher when H2 was not offered as an electron donor. Similar results were obtained from the enrichment culture MP-32, which was grown in medium with reduced salinity compared to the salt cavern brine. Uptake of 13C was 10-fold higher when incubated with H2 and nearly all cells incorporated 2H with and without H2. A total of eight metagenome-assembled genomes (MAGs) with a completion of more than 90 % could be recovered from MP-32. Two of them belonged to Desulfohalobiaceae and can be characterized as autotrophic sulfate reducers by means of the Acetyl-Coenzyme A pathway that compensate osmotic stress by synthesizing small organic molecules. Collectively, our findings provide a new approach to study microbial activity that is strongly impacted by high salinity and an improved understanding of their genomic potential.

High-value application of inorganic–organic surface modification coal gasification fine slag as alternative for calcium carbonate in poly(vinyl chloride) composites

To attain high-value utilization of coal gasification fine slag (CGFS), a mechanical-chemical activation treatment for CGFS was presented in this study. Heavy calcium carbonate (CC) was employed as an equivalent filler. The findings demonstrate that the maximum tensile strength and maximum flexural strength of the Poly(vinyl chloride) PVC/MCS (modified CGFS) composite materials reach 47.74 MPa and 28.8 MPa, which are 12.3% and 55.2% higher than that of PVC, and 14.6% and 13.4% higher than that of PVC/CC with the same amount of CC, respectively. Thermal properties reveal that the PVC/MCS composites have high-temperature thermal stability, and the final residual mass reaches 29.16%, which is 37.9% higher than that of PVC/CC. Therefore, MCS exhibits the potential to serve as a substitute for CC in the PVC market.

The stable isotope (C, O, S) record of Paleoproterozoic marbles, Scotland

Paleoproterozoic marbles occur widely in NW Scotland. The isotopically heavy carbonate carbon ( δ 13 C >3‰) in marbles that characterizes the worldwide Lomagundi–Jatuli Event (2.3–2.05 Ga) is recognized in the Laurentian Foreland, the Moine Nappe and the Sgurr Beag Nappe, over a 150 km transect across the Caledonian thrust belt. A light oxygen isotope composition distinguishes marbles that have been sheared and retrogressed by ingress of meteoric water, possibly during both Laxfordian and Caledonian orogenesis. The shearing of marbles also contributed to graphite formation (mean δ 13 C −7.2‰). Pyrite in the marbles contains isotopically heavy sulfur, typical of Paleoproterozoic diagenetic sulfides precipitated from low-sulfate seawater. These data show that the c. 2 Ga marbles in Scotland are a high-quality archive of information on their depositional and post-depositional history. The data emphasize a continuum of a Paleoproterozoic marble–graphite–sulfide-bearing assemblage from eastern Canada and Greenland through Scotland to Scandinavia.

Preparation of low-cost high strength soluble ceramic cores using heavy calcium carbonate by binder jetting and vacuum impregnation

Binder jetting method was used for printing ceramic green body using heavy calcium carbonate (HCC) processed from dolomite consisting of CaMg(CO3)2 as raw material, and the nano-ZrO2 dispersion was used to vacuum impregnate the ceramic green body. After sintering, the low-cost high strength soluble ceramic core was obtained. The CaO generated after the decomposition of the HCC reacted with the ZrO2 at high temperature to form CaZrO3. This reaction reduced the porosity of the ceramic core, thereby improving its bending strength by 317.6%. The CaZrO3 formed made the sintered ceramic core have certain hydration resistance due to the insolubility of the CaZrO3, extending the use time of the ceramic core. The CaO and MgO generated after the decomposition of the HCC also ensured the good solubility of the ceramic core. This study provides a new method for the preparation of the low-cost high strength soluble ceramic cores by additive manufacturing method.

The relationship of nitrogen nutrition conditions with the productivity of Tamasha potatoes

The article presents the results of three-year (2015-2017) studies research on the influence of nitrogen nutrition conditions on the productivity and quality of potatoes variety Tamasha. The studies were carried out on dark brown heavy loamy carbonate soils of Central Kazakhstan with a humus content of 2.73-2.79 %, total nitrogen - 0.147-0.172 %, total phosphorus - 0.20-0.25 %, with a high level of availability of mobile phosphorus and potassium, low content of nitrate nitrogen, slightly alkaline reaction of soil solution. Studies have shown a high responsiveness of potatoes to nitrogen fertilizers. According to the results of the research, a high correlation between potato productivity and the nitrate nitrogen content in the soil (R=0.85-0.96) was revealed, the optimal level of nitrate nitrogen in the 0-40 cm soil layer was determined for Tamasha potatoes - 17-19 mg/kg. The increased nitrogen content of nitrates in the soil slightly reduced the starchiness of potatoes.

Impact of Heavy Metal and Carbonate on Geotechnical Properties of Sand-Bentonite Mixtures

Impact of Heavy Metal and Carbonate on Geotechnical Properties of Sand-Bentonite Mixtures

Effect of industrial-grade heavy calcium carbonate powder on properties of white high-strength concrete

In order to reduce costs and improve whiteness, industrial-grade heavy calcium carbonate powder (IHCP) is used in white high-strength concrete (WHSC), the influence of IHCP on the workability, whiteness, mechanical properties, chloride ion impermeability, carbonation resistance and shrinkage properties of WHSC is systematically studied, and then the related mechanism were explored by means of XRD, TG-DTG and MIP. The results reveal that IHCP can improve the workability, whiteness and mechanical properties of WHSC, and the more IHCP incorporated, the more obvious the improvement. While IHCP can reduce the impermeability and carbonation resistance of WHSC, and the more the IHCP incorporating, the more obvious the reduction. A low content of IHCP can effectively reduce the drying shrinkage of WHSC, and with the increase of IHCP content, the drying shrinkage of WHSC quickly increases to around without IHCP. Increasing the fineness of IHCP has limited effect on the performance of WHSC, but it will greatly increase the grinding cost of IHCP and the raw material cost of WHSC. WHSC containing 15% of 850 m2/kg IHCP has the highest cost performance.

Accelerated carbonation of ball-milling modified MSWI fly ash: Migration and stabilization of heavy metals

Mechanical ball-milling is an effective technique to reduce particle size, increase lattice defects, and enhance the activity of materials. After mechanical ball-milling modification, an accelerated carbonation technology of municipal solid waste incineration fly ash (FA) was proposed. The effects of ball-milling on carbonation efficiency, heavy metals stabilization, and heavy metals leaching characteristics were investigated. The results showed that the initial carbonation efficiency of ball-milled FA (MFA) was higher than that of the original FA (OFA) because of the in-situ carbonation reaction and the stability of Pb, Cu, and Cd in MFA was improved. The carbonation reaction of MFA was conducted thoroughly by the elevated ionic strength and mass transfer efficiency. The surface of carbonated OFA (COFA) and carbonated MFA (CMFA) stacked calcium carbonation in loose strips and compact spherical respectively, relating to the initial morphology. The dechlorination of CMFA was superior to COFA because the more in-depth carbonation eluted the chlorine from Friedel’s salt. The leaching concentrations of heavy metals in CMFA were lower than those in COFA, especially the immobilization efficiency of Pb and Zn reached 99.8 % and 98.5 %, respectively, contributed by the conversion of the Pb and Zn from ionic hydroxides to stable carbonates. Due to the low acid neutralization capacity of CMFA, when the pH dropped from 7 to 5, the heavy metals carbonate chemical precipitation dissolved, and the effect of calcium carbonation on heavy metals wrapping and adsorption disappeared, therefore the subsequent disposal of CMFA should avoid an acidic environment.

Effect of modified heavy calcium carbonate on properties of crumb rubber modified asphalt binder

ABSTRACT High-temperature rutting is one of the common forms of pavement damage. To further improve the high temperature performance of crumb rubber modified asphalt (CRMA) pavement, heavy calcium carbonate (HCC) modified by sodium pyrophosphate was combined with crumb rubber to prepare composite modified asphalt binder. Their physical properties, viscoelastic properties and chemical composition were investigated through conventional physical tests, DSR, FTIR and fluorescence microscopes. The results show that with the increase of HCC content, the mixing and compaction temperatures of composite modified asphalt binders continued to increase. Further, the high temperature performance and fatigue resistance of binders were better than the original CRMA, due to the enhanced lipophilicity of HCC after modification. It can be found from the FTIR spectrum that the addition of HCC only existed in physical action. However, excessive HCC would cause agglomeration of the asphalt matrix, so the optimum dosage of HCC was determined to be 4%.

RETRACTED ARTICLE: Improvement of seismic data quality and recognition of fault discontinuities through seismic data conditioning applications: a case study of Issaran oil field, Gulf of Suez, Egypt

Obtaining high-quality seismic imaging in shallow heterogeneous carbonate reservoirs with complicated structural regimes, such as the Issaran field, is difficult. Issaran field is a heavy oil shallow heterogeneous fractured carbonate reservoirs located in the Gulf of Suez of Egypt. It has many geological factors that affect image quality and pose numerous challenges. In addition, the seismic data was acquired more than 12 years ago, with narrow azimuth and short offsets. As a result, the fault zones are not sharply defined. Furthermore, the seismic data was processed about 10 years ago. The signal-to-noise ratio is relatively poor due to the random and coherent noises. A robust data conditioning workflow for noise suppression and fault discontinuity sharpening is used to improve the post-stack seismic data quality. In this context, a steering dataset was generated, and a dip-steered median filter (DSMF), a dip-steered diffusion filter, and a fault enhancement filter (FEF) were applied to sharpen the discontinuities. Structural attributes were evaluated, to investigate how the newly applied data conditioning affects the clarity of fault patterns. Furthermore, multiple physical attributes were extracted, including instantaneous phase, instantaneous frequency, and RMS amplitude to better understand the reservoir stratigraphic heterogeneity. The application of DSMF is useful in removing the residual random noises. The FEF-similarity attribute revealed small-scale faults with a 50-foot vertical throw. The physical attributes proved that the Issaran carbonate facies is controlled by structure. Moreover, the RMS amplitude attribute helped in distinguishing between porous and non-porous dolomite facies. As imaging quality has significantly improved, the applied seismic data conditioning workflow is beneficial for the field development in Issaran field. It is also suggested that this data conditioning workflow be applied in other heterogeneous carbonate reservoirs with complex structures around the world.