Fine Slag Research Articles

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.

Mechanical activation of coal gasification fine slag and mechanical and thermal properties of coal gasification fine slag–poly(vinyl chloride) composites

To facilitate the high-value utilization of activate coal gasification fine slag (CGFS), a wet mechanical activation process was used. As a result of this treatment, CGFS samples with different particle size distributions were obtained. The effects of mechanical activation on various physical and chemical properties of CGFS were investigated, including its particle size distribution, mineral composition, specific surface area, pore size, crystallinity, particle morphology, chemical bonding, and binding energy. Poly(vinyl chloride) (PVC)/CGFS composites were prepared via a melt blending process, and their mechanical and thermal properties were evaluated. It was found that with increasing levels of mechanical activation, the CGFS particle size distribution became more concentrated and the particle spacing became more uniform. With the increasing mechanical activation, the crystallinity was found to decrease and the content of amorphous mineral matter (such as SiO2 and Al2O3) increased. The observed increase in specific surface area and decrease in average pore diameter due to the mechanical activation was seen to lead to an increase in the number of active sites. The produced PVC/CGFS composite materials were found to exhibit good mechanical properties and dynamic thermal stability. The thermal stability of the PVC composites was also found to improve relative to the composites produced without the use of mechanical activation.

Dodecylamine enhanced coal gasification fine slag flotation and its molecular dynamics simulation

Coal gasification fine slag (CGFS) is produced by the raw gas flow through the top of the gasifier, and is formed after preliminary washing and purification, precipitation, and dehydration. The CGFS cannot be directly used as building materials or in other industries because of its higher ignition loss than the standard of building mixed raw materials. Neither can it be used for direct combustion because of low carbon content, high moisture content and low calorific value. Currently, its treatment is mainly landfill-based disposal which causes environmental pollution and carbon resources waste. The utilization of CGFS is becoming increasingly urgent and its premise is the separation of ash material and residual carbon. Froth flotation is a common method used for separating fine materials. In this study, kerosene (D1) and a dodecylamine-kerosene mixture (D2) were used as collectors and the flotation performance of CGFS sampled from Ningxia Coal Industry Company was investigated. The results indicate that D2 is better than D1 in that it gives higher yield of concentrate, ash of tailings, and combustible recovery. Pore structure analysis (BET) and scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) were used to characterize the flotation products, which provided a basis for the separate utilization of carbon ash from CGFS. In this paper, a certain percentage of functional groups were grafted onto graphene based on the results of XPS analysis to replace the residual carbon model, and the D2 collector is proved to be more efficient than D1 by two models. Molecular dynamics (MD) simulations was used to simulate the adsorption morphology of D1 and D2 on the surface of residual carbon and the adsorption morphology of D2 on the surface of residual carbon with four functional groups. The results show that D2 has stronger adsorption energy with residual carbon than D1, and the electrostatic forces play a certain role. The adsorption energy of D2 with four functional groups decreases from carboxyl, carbonyl, hydroxyl, to ether bonds. Some dodecylamine molecules help kerosene to form smaller oil droplets that act on the carbon residue surface through van der Waals (vdW) force and electrostatic force, while other dodecylamine molecules form hydrogen bonds with oxygen-containing functional groups on the carbon surface to cover some hydrophilic points. This significantly increases the hydrophobicity of the residual carbon and enhances its flotation effect.

Estimation of hot metal desulfurization by intermediate and final blast-furnace slag when using pellets of different basicity in blast-furnace charge

n the process of blast-furnace smelting, up to 90% of coke sulfur is captured by the iron ore charge, accumulating in hot metal in the amount that was absorbed from the gas phase. Desulphurization of cast iron occurs when it interacts first with the intermediate, and at the final stage, with the final blast-furnace slag. In this regard, it is of interest to evaluate the desulfurizing properties of the intermediate and final slag, which affect the sulfur content in hot metal. Melting mixtures of pellets of different basicity and sinter in a blast furnace leads to the formation of primary and intermediate slags of different chemical composition. When smelting hot metal in blast furnaces, mainly unfluxed pel-lets and fluxed sinter are used. In the course of the study, mixtures of sinter and pellets of different basicity were pre-pared, which ensured the production of final blast-furnace slag with a basicity of CaO/SiO2 = 1.15 units. The mixtures were reduced and melted in graphite crucibles with the smelting products filtered through a coke nozzle. The coeffi-cients of sulfur distribution between intermediate slag and hot metal obtained from iron ore charge with different basicity of sinter and pellets were determined. The lowest sulfur distribution coefficient between the intermediate slag and hot metal is observed when the basicity of the pellets is in the range of 0.5‒1.2 units. To increase the desulfurization capacity of the intermediate slag, it is advisable to use unfluxed and fluxed pellets with a basicity of 0.25 units in the blast-furnace charge and an sinter with a basicity of 1.78‒1.87 units. Studies of the kinetics of the interaction of hot metal and final blast-furnace slag have shown that the final slag provides a high degree of desulfurization of hot metal during their interaction for 1 hour or more

Cyclic catalytic Fe-N doped composite particle electrodes derived from gasification fine slag for non-selective mineralization of organic wastewater

As a typical coal-based solid waste, coal gasification fine slag (GFS) will have an annual discharge of more than 50 million tons in 2025 in China alone. However, the difficulty of its resource utilization lies in the precise separation of carbon and ash due to their complex distribution pattern. There is an urgent need to develop GFS-based materials for comprehensive utilization of carbon and ash. In this study, a combined process of acid leaching and pyrolysis was designed, in which active metal iron was leached from ash and immobilized on the surface of residual carbon in the form of Fe-N-C. The unique structure of Fe-N doped carbon/ash synergistically improved the efficiency of electrocatalytic degradation of organic wastewater by 72.78 ± 1.37%. The hierarchical porous structure of residual carbon considerably enhanced the accessibility of ash catalytic sites. Abundant ash defects and Fe-N active sites promoted the conversion of free radical precursors to reactive oxygen species (ROS). The removal rate of various organic wastewater within 35 min reached more than 100 ± 1.83% %, with excellent electrocatalytic performance and pH adaptability. Fe-NCPE had a high specific surface area (318.36 m2·g−1), orderly graphite phase (002 crystal surface size 1.3 nm), and abundant catalytic sites. We also proposed the catalytic mechanism by combining molecular simulation with experiments. The high adsorption capacity above 24.07 ± 0.12 mg·g−1 ensured the continuous and rapid supply of pollutants and H2O2 near the catalytic site·H2O2 was converted into ROS mainly composed of hydroxyl groups through the valence state change of aluminum or Fenton-like reaction of nitrogen-linked iron. The ROS then attacked organic molecules to degrade pollutants. The above two processes corresponded to two cyclic catalytic reactions. Therefore, this study provides an innovative and promising approach for comprehensive utilization of carbon and ash in GFS.

Improvement of microporous structure and impermeability of cement mortars using fly ash and blast furnace slag under low curing pressures

Low air pressures in high plateau will degrade the impermeability and air void structure of cement mortars. In this study, the feasibility and mechanism of fly ash (FA) and ground granulated blast furnace slag (GGBFS) improving the microporous structure and impermeability of cement mortars under low curing pressure were investigated. Results showed that the slag significantly improved the impermeability and air voids distribution of cement mortars, while the fly ash did not benefit the impermeability, as well as the air void in mixed mortars. The heat releasing rate and hydration product composition of the slag mixed paste were superior to that of the FA. The reduction of Ca(OH)2, gentler hydration rate, and filling effect of fine slag particles are believed to contribute to the improvement of impermeability. The water vapor isotherm sorption test demonstrated that low curing pressure changed the surface characteristics of hydrates, and inhibited the adsorption and desorption process (including the capillary condensation process and ink-bottle effect) with the range of relative humidity (RH) > 40%. Meanwhile, the titting parameters variation certified according to Guggenheim-Anderson-deBoer (GAB) model certified that the addition of slag achieved the same result as increasing curing pressure. Moreover, futher analysis showed that if partial OPC was replaced by slag, it could befinit energy consumption, CO2 emission, and materials cost compared with pure OPC. This study provides an initial evidence for applications of slag in low air pressure conditions.

Environmental, economic and engineering performances of aqueous carbonated steel slag powders as alternative material in cement pastes: Influence of particle size

The low reactivity and volume expansion issue of steel slag limits its application as alternative to cement. Studies demonstrated that aqueous carbonation (AC) can enhance the cementitious properties of finely sized steel slag as a cementitious supplementary material (SCM). However, the impact of particle size on the CO2 uptake capacity and its association of performance of carbonated steel slag remains unexplored. This study aims to optimize the grinding levels by examining the fineness of the steel slag used as SCM to reduce the high-energy consumption while maintaining the CO2 sequestration and properties of SCM. The results show that reducing the size of steel slag is favorable for CO2 sequestration (particle size 22.4–112.6 μm corresponds to sequestration of ∼88.5–37.9 kg CO2/t steel slag) and improve the leaching of Mg ions for mineralization. The life cycle assessment shows that the global warming potential of AC of steel slag is ∼96.2–24.9 kg CO2-eq/t steel slag, which can offset the carbon emissions due to further grinding. The 28-day compressive strength of the cement pastes blended with finer carbonated steel slag was also relatively higher due to the formation of mono-carboaluminates and stabilization of ettringite in facilitating the bond strength between the carbonated steel slag particle and the cement paste matrix. According to 3E (engineering, environmental and economic) triangle model, 22.4 μm steel slag powder showed the best comprehensive performance, including an increased revenue of 40.8 CNY/ton steel slag.

Flow Properties of Entrained Flow Gasifier Fine Slag and Network Structure of its Molten Slag

Flow Properties of Entrained Flow Gasifier Fine Slag and Network Structure of its Molten Slag

Promotion of hydrophobic-hydrophilic separation of coal gasification fine slag through ultrasonic pre-treatment

Coal gasification fine slag (CGFS) is a solid waste byproduct generated during the coal gasification process. However, the high content of residual carbon hinders its potential for resource utilization. The urgent need for an efficient carbon extraction and ash reduction technology is evident. Hydrophobic–hydrophilic separation (HHS) is a technology that enriches hydrophobic particles in the oil phase while hydrophilic particles are in the water phase by stirring, and the different hydrophobic particles are separated by the separation of the oil and water phases. The molecular dynamics simulations revealed that the adsorption of n-heptane onto the residual carbon surface occurred spontaneously and was primarily driven by van der Waals forces. Ultrasonic pre-treatment pulp could enhance the effect of HHS. The fluctuation in tailings ash did not exceed 2% while the concentrate ash was reduced from 31.81% to 18.93% with a continual increase in ultrasonic power. The application of ultrasonic treatment on CGFS facilitated the separation of Carbon-ash molten state, as well as the elimination of ash materials particles residing within the pores of the residual carbon matrix and on its surface. Notably, many residual carbon particles are concentrated in the particle size range of 0.045–0 mm. The heightened hydrophobicity exhibited by particles within this size range enhanced the capture of oil droplets, thereby promoting the efficiency of HHS. This research aims to provide technical support and theoretical foundation for utilizing ultrasonic pretreatment as a means to enhance the HHS efficiency of CGFS.

Ontology Framework for Sustainability Evaluation of Cement–Steel-Slag-Stabilized Soft Soil Based on Life Cycle Assessment Approach

Steel slag has become a promising supplementary cementitious material for soft soil stabilization. However, there is a lack of research on the integrated assessment of cement–steel-slag-stabilized soft soils (SCSs) from the performance, environmental, and economic perspectives. In this study, an ontology framework for the sustainable evaluation of SCSs was developed based on the life cycle assessment (LCA) approach, which combined a knowledge base with semantic web rules to achieve an automated decision design for soft soil stabilization, considering comprehensive benefits. The ontology framework was applied to a marine soft soil stabilization case to verify its scientificity and practicability and to evaluate the influence of the fineness, carbonation degree, and substitution ratio of steel slag on the sustainability of SCSs. The results show that, when compared to pure-cement-stabilized soil (S-C), using 10% and 20% of fine steel slag carbonated for 18 h (FSS-C-18h) as cement substitutes can significantly reduce carbon emissions and costs while achieving a similar strength performance as S-C, demonstrating the feasibility of steel slag as a sustainable supplementary cementitious material for soft soil stabilization.

A clean process for preparing ferrosilicon alloy from coal gasification fine slag by carbothermal reduction processing

The unreasonable treatment method of coal gasification fine slag (CGFS) in the industry has led to a serious waste of resources and environmental pollution, so it is of great significance to solve the problem. In this study, ferrosilicon alloy was successfully prepared from CGFS by carbothermal reduction processing, and the transformation of powdered CGFS to SiC-(Al2O3-CaO-SiO2) composite material was realized by the high-temperature vitrification process. The highest yield of ferrosilicon alloy was 35.23 % and the main compositions of the alloy were Si: 32.10 wt%, Fe: 60.52 wt%, Al: 1.93 wt%, Ca: 0.87 wt%, Ti: 2.56 wt% under the optimal smelting parameters: smelting temperature: 1800 °C; carbon content: 80 % of the theoretical value; holding time: 15 min. The final product slag was a mixed glass phase of SiC and Al2O3-CaO-SiO2, which can be used as raw material in ceramic materials preparation. Whether SiC is generated in large quantities has an important influence on the smelting process because the melted oxide will adhere to the SiC whiskers and limit the carbothermal reduction reaction. This work provides a theoretical foundation for the large-scale and high-value utilization of CGFS.

Preparation of activated carbon adsorption materials derived from coal gasification fine slag via low-temperature air activation

Considering the considerable amount of residual carbon in coal gasification fine slag (CGFS) and the issue of lacking effective treatments, it is imperative to put forward a large-scale, green, and efficient method, achieving quantity reduction and harmless disposal. A kind of activated carbon adsorption material was prepared from CGFS with abundant carbon content (nearly 33.61 wt%) by low-temperature air activation. The CGFS-20 showed the best performance, whose specific surface area and pore volume increased by 21.5% and 7.8%, respectively. It is attributed to the slight oxidation of combustibles (main carbon) and removal of hydrocarbons blocked in pores, which can be further confirmed by FT-IR and pore analysis. In addition, the pores generated through activation are more concentrated in the 1.4–5 nm range. While the proportion of micropores, mesopores, and macropores of different activated samples did not change significantly, implying that the generation and development of pores make it realize a dynamic balance of three pore proportions. The CO2 adsorption of CGFS and CGFS-20 combined with the Langmuir model was investigated and revealed that the theoretical maximum adsorption for CO2 was 21.03 cm3/g.

Kinetic study of mechanical and thermal properties and thermal degradation of PVC composites based on coal gasification fine slag

Coal gasification fine slag (CGFS) is a by-product of gasification process of gasification beds that pollutes the environment. To make the utilization of CGF more efficient, poly (vinyl chloride) (PVC)/CGFS composites were prepared via a melt blending process, and their mechanical and thermal properties were investigated. In order to dig deeper into the decomposition mechanism, the thermal degradation kinetics were systematically analyzed by drawing non-isothermal heat maps based on the Flynn-Wall-Ozawa, Friedman, and Kissinger model-free methods. According to the results, the properties of all tests vary significantly with CGFS content. In particular, at a the CGFS content of 20 phr, the tensile strength (tensile modulus) and flexural strength (flexural modulus) of CGFS-20 were 13.5% (47.8%) and 13.9% (41.6%) higher, respectively, than those of conventional CGFS-0 composites. However, the impact strength decreases with the increase of CGFS content. At the same time, the addition of CGFS suppresses the mass conversion rate and improves the thermal stability of PVC composites at high temperature, and the final residual mass reaches 31%, which is 12.7% higher than that of pure PVC. The kinetic analysis of thermal decomposition shows that CGFS promotes the initial degradation of the composites reduces the activation energy of the reaction, and at the same time endows them with higher thermal stability in the high-temperature phase.

Coal gasification fine slag based multifunctional nanoporous silica microspheres for synergistic adsorption of Pb(II) and Congo red

The discharge of large-scale industrial solid waste and wastewater has caused severe damage to environmental health. In this study, the adsorption behaviors of Pb(II) and Congo Red (CR) dye in single and binary aqueous systems were investigated using novel functionalized nanoporous glass microspheres (NGM). The NGM material was fabricated from coal gasification fine slag (CGFS) by a simple treatment and characterized using TG, BET, XRD, TEM, FT-IR, and XPS to analyze its physicochemical properties. The adsorption experiments showed that the adsorption amounts of DMA-NGM for Pb(II) and CR were 302.39 mg/g and 342.74 mg/g for the single systems, and 372.73 mg/g and 412.93 mg/g for the binary systems, respectively. The increased adsorption capacity was attributed to the synergistic effect of electrostatic attraction and chelation. Furthermore, the pseudo-second-order model and Elovich model could reasonably describe the adsorption of Pb(II) and CR on DMA-NGM. Pb(II) adsorption on DMA-NGM was monolayer adsorption and CR adsorption was multilayer adsorption. In summary, the results demonstrate the potential of efficient and environmentally friendly adsorbents for the resource recovery of CGFS and the processing of printing and dyeing wastewater.

Co-combustion of carbon-rich fraction from coal gasification fine slag and biochar: Gas emission, ash sintering, heavy metals evolutions and environmental risk evaluation

Mixed combustion of carbon-rich fraction (RC) from coal gasification fine slag and corncob char (CC) is an effective way of energy recycling. In this paper, the co-firing performance and kinetics of RC and CC were studied, and gas emission pattern, ash sintering trend and the migration and transformation behavior of heavy metals during combustion were explored. The results showed that the combustion performance was enhanced and the reaction activation energy was reduced during the blends burning. The synergistic effect between co-combustion reactions decreased emissions of gaseous pollutants. With the increasing RC compounding ratio and combustion temperature, the ash sintering tendency weakened. Cr and Ni were mostly enriched in the bottom ash, whereas Cu, Zn, As, Cd, and Pb tended to migrate to fly ash and flue gas. Cu, Zn, As, and Pb were in the form of stable fractions. Temperatures accelerated the chemical forms of Cr, Ni, Cu, Zn, and Cd being transformed into stable fractions. The environmental evaluation index suggested that the potential environmental risks of Cr, Zn, Cd, and As were relatively high. The results of this study provide guidance for the synergistic combustion disposal of double solid waste.

Molecular simulation investigation of pore structure impact on the wettability and flotation efficiency of coal gasification fine slag

Coal gasification slag is a kind of solid waste that exhibits suboptimal resource utilization and contributes to environmental pollution. Flotation is a common method of sorting coal gasification fine slag. However, the adverse influence of the well-developed pores structure of residual carbon on wettability and flotation efficiency is not adequately addressed in the literature. In this research, the adsorption characteristics of water molecules in the residual carbon model with different pore structures were investigated by Grand Canonical Monte Carlo simulation. We employed molecular dynamics simulations and mathematical models to investigate the mechanism of pore water movement. Additionally, the influence of pore structure on the flotation effect of coal gasification fine slag was explored for molecular dynamics simulations and flotation experiments. The results indicated that water molecules were adsorbed and aggregated in the residual carbon pores in the form of clusters. The cluster size decreased as the porosity decreased. Moreover, the same pore model showed an equivalent adsorption of water molecules. The binding effect of residual carbon on water molecules was stronger for smaller pore sizes. However, the simulation and experimental findings demonstrated that the more developed the pore structure of coal gasification fine slag, the lower its flotation efficiency. Finally, various methods of strengthening the flotation of coal gasification fine slag are theoretically verified. The findings of this research elucidate the underlying microscopic mechanism responsible for the adsorption of water molecules by residual carbon pores. Moreover, we explicate the principle of weakening the pore wetting effect and lay a theoretical foundation for developing advanced flotation techniques for coal gasification fine slag. It provides some theoretical guidance and technical support for realizing high-value utilization of coal gasification slag with specific environmental and resource benefits.

Emission characteristics of coal gasification fine slag direct combustion and co-firing with coal

Coal gasification is an effective way to use coal cleanly and efficiently, and coal gasification fine slag is a by-product of coal gasification with high carbon content, large specific surface area, developed pore structure and large output during production. At present, combustion has become an effective way to dispose of coal gasification fine slag on a large scale, and the coal gasification fine slag after combustion treatment can be further used for construction raw materials. In this paper, the emission characteristics of gas-phase pollutants and particulate matter under different combustion temperatures (900 °C, 1100 °C, 1300 °C) and combustion atmosphere (5%, 10%, 21% O2 concentration) are studied with the drop tube furnace experimental system. By co-firing different proportions of coal gasification fine slag (10%, 20%, 30%) and raw coal, the pollutants formation law under co-firing conditions is studied. Scanning electron microscopy-energy spectroscopy (SEM-EDS) is used to characterize the apparent morphology and elemental composition of particulate samples. The measurement results of gas-phase pollutants show that the increase of furnace temperature and O2 concentration can effectively promote combustion and improve burnout characteristics, but the emission of gas-phase pollutants increases. A certain proportion (10%–30%) of coal gasification fine slag is added to the raw coal, which reduces the total emission of gas-phase pollutants (NOx and SOx). Studies on the characteristics of particulate matter formation show that co-firing with coal gasification fine slag in raw coal can effectively reduce submicron particle emission, and the lower fine particle emission is also detected at lower furnace temperature and oxygen concentration. The element analysis of particulate matter formation shows that the Fe, Si and S elements content of submicron particle generated by YL (the coal gasification fine slag generated by water slurry furnace in of Shaanxi Extended China Coal Yulin Energy Chemical Co., Ltd) sample increases significantly with the increase of furnace temperature and O2 concentration, which is the main influencing factor for the increase of submicron particle. With the increase of the mixing ratio of YL sample, the content of major elements such as Fe, K and Mg of submicron particle decreases significantly, which is an important reason why the amount of the submicron particle decreases.

Characterizing moisture occurrence state in coal gasification fine slag filter cake using low field nuclear magnetic resonance technology

ABSTRACT Gasification fine slag, a carbon-rich solid waste produced during coal gasification, is currently disposed of through conventional landfilling methods. Its high-water content hampers resource utilization by reducing its calorific value. This study employs low field nuclear magnetic resonance (LF-NMR) analysis to investigate the water occurrence states in a filter cake with 70.7% moisture content derived from fine gasification slag of the Ningxia coal water slurry furnace. The analysis reveals that free water constitutes a major proportion (68.28%), while combined and capillary water accounts for 2.62% and 2.33%, respectively. The removal of moisture from the coal gasification fine slag filter cake is significantly affected by the drying temperature. The drying rate initially increases and then decreases with different temperatures. For drying temperatures of 60, 70, 80, 90, and 100°C, the maximum drying rates are achieved at 1.09, 1.23, 2.18, 3.86, and 4.01%/min, respectively, with corresponding durations of 40, 40, 25, 30, and 35 min. The T22 relaxation peak area continually decreases and shifts leftward on the coordinate axis. The behavior of the T23 and T22 peaks follows a similar pattern, indicating that water with higher mobility is easily eliminated during drying, while the T21 peak exhibits a robust signal strength throughout the drying process. At a drying temperature of 100°C, the proportion of free water (A22) decreases from 87.3% to 0, the A23 fluctuates between 0 and 5.3%, and the bound water peak area (A21) increases from 10.4% to 94.7% as drying time prolongs. A relationship model is developed between the moisture content of the coal gasification fine slag filter cake and the total integral area of the LF-NMR test, enabling rapid detection and analysis of the total moisture content and distinct occurrence states in the filter cake.

Study on recovery of residual carbon from coal gasification fine slag and the influence of oxidation on its characteristics

Coal gasification fine slag (CGFS) is a kind of solid waste that is difficult to separate and utilize. In this work, ultrasonic-assisted flotation was used to recover residual carbon (RC) from CGFS. The ultrasonic treatment not only promotes the separation of RC and ash, but also improves the surface hydrophobicity of CGFS. Compared with conventional flotation, the loss on ignition (LOI) of concentrates and flotation perfect index obtained by ultrasonic-assisted flotation were increased by 12.21% and 4.57%, respectively. In addition, the RC was modified by air and steam. The characterization results of the samples show that air oxidation can significantly improve the oxygen-containing groups on the RC surface, especially the CO groups, and steam treatment is more conducive to increase the disorder of carbon microstructure. Furthermore, the textural properties of the RC were developed by air-steam treatment, and the highest specific surface area and pore volume of the oxidized RC were increased by 27.25 times and 6 times than the raw RC, respectively. RC-A2S2 obtained by air-steam alternating treatment had a high CO2 storage capacity of 2.00 mmol/g at 25 °C. The above research results have important reference value for strengthening of CGFS flotation and utilization of RC.

Coal gasification fine slag doped with Fe3O4: High-performance electromagnetic-wave absorbers

The pursuit of electromagnetic absorbers with high-performance characteristics has led to a growing appreciation for easily prepared and environmentally friendly methods. In this study, heterostructured multi-interface Fe3O4@Coal gasification fine slag (CGFS) composites were directly prepared via coprecipitation of Fe3O4 nanoparticles (NPs) and untreated coal gasification fine slag. The composite material was subjected to analysis of its magnetic properties, crystal structure, composition, electromagnetic parameters, and morphology, resulting in the determination that the material achieved a minimal reflection loss (RLmin) of –28.10 dB at 10.00 GHz at a thickness of 2.7 mm (Fe3O4@FS-1). Broadband microwave attenuation covers 4.00 GHz at a thickness of 1.7 mm (Fe3O4@FS-2). The exceptional performance of Fe3O4@CGFS composites in absorbing electromagnetic waves (EMWs) is attributed to a combination of factors, including appropriate impedance matching, dielectric and magnetic losses, and a multi-interface design, resulting in a synergistic effect. The CST simulation clearly indicated that the Fe3O4@FS-1 composite is capable of significantly reducing the radar cross-section value under realistic conditions. The corrosion resistance test results show that the Fe3O4@CGFS composites has good chemical stability. Overall, the high graphite residual carbon content in CGFS provides a foundation for reducing the preparation conditions of EMW absorbers while maintaining superior electromagnetic-wave absorption and dielectric losses, thereby expanding the high-value utilization of CGFS.