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Cement production may involve excessive use of natural resources and have negative environmental impacts, as energy consumption and CO2 emissions can cause air pollution and climate change. Cement kiln dust (CKD), a by-product waste material, is also a primary issue associated with cement production. Utilizing CKD in mining applications is a pathway to eco-sustainable solutions. Cemented paste backfill (CPB) made with mine tailings is an efficient method for void backfilling in underground mines. Therefore, this study investigated the eco-sustainable utilization of CKD as a co-binder material that can partially replace cement in CPB prepared with copper tailings. At 7, 14, 28, 56, and 90-day curing times, the experimental campaign measured the physical and mechanical parameters of the cured CPB samples, including density, UCS, and elastic modulus (stiffness). Additionally, the CPB-cured mixes were analyzed using XRF, X-ray XRD, SEM, and EDX techniques to link the mineral phases and microstructure to mechanical performance. Four proportions (5, 10, 15, and 20%) of CKD represented in 75 samples were prepared to replace ordinary Portland cement (OPC) in the CPB mixtures, in addition to the reference mix (control) with 0% CKD. As all combinations exceed the compressive strength of CPB required for achieving stability in underground mines, the results showed that CKD could be utilized advantageously as a partial substitute for OPC with a proportion of up to 20% in the CPB mixture. When tested after 90 days, the combination modified with 5% CKD exhibited comparatively higher compressive strength than the control mixture. [ABSTRACT FROM AUTHOR]

Soft soil concerns, due to high compressibility and low bearing capacity, prompted an investigation into stabilizing clay soil. Traditionally, binder including cement or lime has been used as stabilizers though a current requirement of alternatives is stem from environmental concerns. The study focused on the viability of using a novel binary activated blended binder composed of environmentally friendly materials, namely ground granulated blast furnace slag (GGBS) activated by cement kiln dust (CKD). The experimental work included investigating the impact of the developed binders on the Atterberg limits, standard Proctor compaction, California Bearing Ratio (CBR), unconfined compressive strength (UCS), and field-emission scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy. CBR tests were conducted after 7 days of curing or soaking, while UCS and SEM analyses were conducted after 7 and 28 days of curing. A fixed binder ratio of 9% was maintained, with GGBS blended at 25%, 50%, and 75% with CKD. For comparison, samples of untreated and treated soils with unary binders from GGBS and CKD were also prepared. Results indicated that activated binders notably decreased soil plasticity and maximum dry density, while elevating optimum moisture content, CBR, and UCS, especially in later stages of treated soil and unary GGBS binder. Unary CKD binder exhibited a similar trend to activated binders. The activating of 25% GGBS with 75% CKD provided the optimum binder which increased the mechanical strengths by about 6 times than untreated soil. SEM revealed substantial formations of C-S-H and C-A-H gel, along with ettringite, intensifying with time. This research provides viable outcomes for stabilizing clay soil using environmentally friendly binders, demonstrating significant improvements in soil properties, particularly when using the binary activated blended binder consisting of GGBS and CKD. [ABSTRACT FROM AUTHOR]

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In this work, cement kiln dust (CKD) will be studied as an unconventional filler for ethylene-propylene-diene terpolymer (EPDM) rubber as an alternative to silica, which is widely used as filler for many types of rubber. (EPDM)/CKD rubber composites were fabricated using ionizing radiation. EPDM rubber was blended with different portions of cement-kiln dust 5, 10, 15, 20, 25, and 30 phr (phr = parts per hundred rubber). The prepared composites were cured by exposing to different doses of gamma rays up to 150 kGy to enhance the crosslinking of the EPDM rubber. The thermo-mechanical properties of the EPDM/CKD and EPDM/Si composites were investigated as a function of irradiation dose. The results showed a significant improvement in elongation and tensile strength by incorporating cement dust into EPDM rubber up to 20 phr, which is not significantly different from composites incorporated with silica. Gamma irradiation significantly improved the properties of all formulations. [ABSTRACT FROM AUTHOR]

This article introduces a novel multiple-cycle generation system for efficient heat recovery at high and low temperatures. The system is modeled and optimized using the M2EP analysis method (mass, energy, exergy, and performance) and the particle swarm optimization algorithm. The multigeneration system produces electricity, cold, domestic hot water, and biogas by utilizing Kalina cycles, diffusion–absorption refrigeration machines, and high-performance heat exchangers by harnessing waste heat from cement kiln exhaust gases. The Kalina cycle is employed for electricity generation, wherein the H2O+NH3 mixture, heated by hot water, circulates through heat exchangers. Downstream of the Kalina cycle, the refrigeration machine generates cold by evaporating the strong solution of the H2O+NH3 mixture. Hydrogen circulates in the diffusion–absorption refrigerator (DAR) circuit, facilitating the exchange between the evaporator and the absorber. The domestic hot water and biogas production systems operate at lower temperatures (around 45 °C). The simulation results for the Kalina cycle indicate an electrical energy production of 2565.03 kW, with a release of usable energy (residual gases) estimated at 7368.20 kW and a thermal efficiency of 22.15%. Exergy destruction is highest at heat exchanger 1, accounting for 26% of the total. A coefficient of performance of 0.268 and an evaporator temperature of 10.57 °C were obtained for the DAR cycle. The absorber contributes the most to energy exchanges, comprising 37% of the entire circuit. Summarizing the potential for valorizing waste heat from cement kilns, this article lays the foundation for future research. [ABSTRACT FROM AUTHOR]

In this study, this process has been modeled and optimized using the design of experiment technique and response surface methodology (RSM). The RSM was employed to optimize the combustion process in the cement kiln. Kiln feed (X1 = 160–190 t h−1), fan speed (X2 = 840–870 rpm), kiln rotational speed (X3 = 2.8–3.4 rpm), kiln fuel rate (X4 = 3800–4150 L h−1), calciner fuel rate (X5 = 5700–6200 L h−1), pressure of kiln inlet (X6 = 98–102 Pa), and limestone saturation factor (LSF) (X7 = 94–95.8 %) as independent variables were investigated. The carbon monoxide and the kiln body temperature in RSM were considered as response variables. The absolute average error in the model predictions for the combustion process in the cement kiln, for the kiln body's temperature, is about 1.6 % and for carbon monoxide is about 15.5 %. [ABSTRACT FROM AUTHOR]

Mixtures of variable proportions of kaolin, quartz sand, zeolitic tuff, and cement kiln dust were blended while adding an 8 M sodium hydroxide (NaOH) solution to allow alkali-activation of kaolin and achieve the optimum strength. This study investigated the mineralogy, microstructure, and geotechnical properties of the prepared mixtures. The aim was to produce a sustainable, environmentally friendly landfill liner. The samples were compacted in stainless steel molds to a maximum dry density and optimum moisture content, extruded from the molds, and left to cure in an oven at varying temperatures from 40°C to 80°C for 24 h. The investigations included XRD, SEM, unconfined compressive strength, and hydraulic conductivity tests. Test results showed the development of a hydroxysodalite binder due to the alkali reaction of kaolin, which caused an increase in strength ranging from 20 to 25 MPa depending on the curing temperature. Alkaline activation was effective even at temperatures as low as 40°C. A mixture of 100 units of kaolin, 45 units of sand, 45 units of zeolitic tuff, and 10% by weight cement kiln dust (CKD) with an 8 M sodium hydroxide activator was found to best achieve the required strength and hydraulic conductivity of 10-9 m/s for the landfill liner. The zeolitic tuff with high cation exchange capacity, available in the mixture, absorbs contaminants in the leachate and prevents pollution of the groundwater. The use of cement kiln dust contributes to enhancing strength and solving an acute environmental problem. [ABSTRACT FROM AUTHOR]

The examinations of concrete involved partial substitution of cement with cement kiln dust (CKD) 0, 5, 10, 20 and 30%. The water/cement (w/c) ratio amounted to 0.36. The obtained findings pertaining to open porosity, density, and volumetric density were found to correlate with the capillary action and absorptivity of the analyzed types of concrete. With the maximum addition of CKD, i.e. 30%, open porosity decreased by 35%. In turn, CKD added in the amount of 5% resulted in a slightly reduced addition compressive strength, amounting to 1.3% and 2.1% following 28 days and 56 days of concrete curing, respectively. After 28 days, the differences in strength were greater when the additive was supplied in higher amounts, i.e. 10%, 20%, and 30%, resulting in 6.5%, 13.4%, and 22.9% decrease, respectively, in spite of strength improvement. In terms of flexural and splitting tensile strengths, comparable relations were noted. As far as the frost resistance test results are concerned, the mass losses in all examined concretes were not significant, reaching up to 0.5%. The strength reduction in the case of the first three series of concretes was below 3%. When the CKD addition was increased to 20% and 30%, the value of the dynamic modulus of elasticity Ec,s decreased to a greater degree, by 8.0% and 14.7%, respectively. The hydrophobization effect is best seen in CKD-free concrete. After the impregnation, the loss of mass following the frost test of the samples is reduced by half. With a higher CKD content, the hydrophobization effectiveness is insignificant. The most favourable results were observed for hydrophobization with the oligomer-based preparation A1. [ABSTRACT FROM AUTHOR]

• A life cycle assessment (LCA) of solid recovered fuel (SRF) was conducted. • SRF production process contributes to about 35.6 kg CO 2 -eq per ton. • A maximum of −1752.03 kg CO 2 -eq was obtained with about 80 % of SRF biogenic carbon. • A footprint of −542.09 to −1729.05 kg CO 2 -eq can be found due to coke substitution. • The study recommended SRF production to mitigate the global carbon footprint. Solid recovered fuel (SRF) from non-recyclable waste obtained from source separation and mechanical treatments can replace carbon coke in cement plants, contributing to the carbon neutrality. A life cycle assessment (LCA) of the SRF production from non-recyclable and selected waste was conducted in an Italian mechanical treatment plant to estimate the potential environmental impacts per ton of SRF produced. The analysis would contribute to evaluate the benefits that can be obtained due to coke substitution in best- and worst-case scenarios. The avoided impacts achieved were assessed, together with an evaluation of the variables that can affect the environmental benefits: SRF biogenic carbon content (in percentage of paper and cardboard); transportation distances travelled from the treatment plant to the cement kiln; the renewable energy used in the mechanical facility. On average, about 35.6 kgCO 2 -eq are generated by the SRF transportation and production phase. These impacts are greatly compensated by coke substitution, obtaining a net value of about −1.1 tCO 2 -eq avoided per ton of SRF. On balance, the global warming potential due to SRF production and consumption ranges from about −542 kgCO 2 -eq to about −1729 kgCO 2 -eq. The research recommended the use of SRF to substitute coke in cement kilns also in low densely-populated areas to mitigate environmental impacts and achieve carbon neutrality at a global level. [ABSTRACT FROM AUTHOR]

Silica fume is usually used in UHPC, three times more than that for normal concrete, to enhance mechanical properties and durability. However, silica fume (SF) is an expensive material and has high production costs. This work is aimed at investigating the shrinkage and durability performance of previously developed UHPC mixtures utilizing the two calcareous waste materials, namely limestone powder (LSP) and cement kiln dust (CKD), by partially replacing the silica fume. The optimally selected mixtures of UHPC, having flow and strength above the minimum required, were used for detailed investigation in terms of shrinkage and durability characteristics. The results showed that by replacing SF with up to 20% of LSP and up to 20% of CKD, the mechanical properties of UHPC remained satisfactory compared to the control mixture with 100% SF. However, the ultimate shrinkage was higher for mixtures incorporating LSP or CKD, indicating the need for more volume of steel fibers to compensate for the shrinkage strains. The developed UHPCs also exhibited high resistance against reinforcement corrosion and sulfate attack, making them suitable for use in aggressive exposure conditions. However, special attention needs to be paid to the CKD content, where it is recommended to limit the content of CKD to about 15% or less to control the durability performance of the UHPCs. In addition, the sustainability analysis of developed UHPC mixtures was carried out using the life-cycle assessment and eco-strength intensity index. The results indicated that the UHPC mixtures possess a higher life-cycle and are therefore more sustainable. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co-incineration biodried products in cement kilns were researched. • Combustion performance of biodried products was better than that of sewage sludge. • Heat efficiency of biodried products during co-incineration was 93.7%. • Co-incineration leads to increased SO 2 and NO X emission concentrations. • Biodried product as fuels have greater potential to reduce carbon emissions. The biodrying technology as a pretreatment technology can overcome the limitations of cement kilns co-incineration sewage sludge (SS) on energy consumption. But the impact of SS biodried products on cement kilns and the route carbon reduction potential of biodrying + cement kilns have not been studied. In this study, SS biodrying and cement kiln co-incineration biodried product trials were conducted to highlight the matrix combustion characteristics, and the impact of biodried products on cement kilns (clinker capacity, coal consumption, and pollutant discharge). The carbon emissions of the four scenarios were assessed based on these results. The results showed that water removal rate reached 65.5 % after 11-day biodrying, and the wet-based lower heating value of the biodried product increased by 76.0 % compared with the initial matrix. Comprehensive combustibility index of the biodried product (0.745 × 10−7 %2℃−3min−2) was better than that of SS (0.433 × 10−7 %2℃−3min−2) although a portion of the organic matter was degraded. Cement kiln co-incineration of biodried products (150 t/d) resulted in per tonne of clinker saved 5.61 kg of coal due to the heat utilization efficiency of biodried products reached to 93.7 %. However, it led to an increase in the emission concentrations of NO X and SO 2. Assessment results indicated that the biodrying + cement kiln pathway reduced CO 2 emissions by 385.7 kg/t SS. Biodried products have greater potential to reduce emissions as alternative fuels than as fertilizers. This study indicated the advantages of SS biodrying + cement kiln co-incineration route. [ABSTRACT FROM AUTHOR]

Cement kiln dust (CKD) is a by-product of cement production, which has the shortcomings of low utilization and high-temperature activation. This study combined CKD and slag as precursors for preparing pastes through quicklime activation under ambient conditions. The effects of quicklime and CKD content on the workability (flowability and setting time), macro-mechanical properties, and micro-structure of the CKD-slag binders were analyzed. The experimental results showed that the rapid precipitation of Ca2+, Si4+, and Al3+ ions from the CKD provided more nucleation sites for the formation of calcium aluminosilicate hydrate (C-(A)-S-H) gel and enhanced the reactivity of the binder system under the influence of the activator (CaO). The specimens had the highest unconfined compressive strength (UCS) (24.6 MPa) after 28 days with 10% quicklime content and 60% CKD content; scanning electron microscopy with energy-dispersive X-ray (SEM-EDX) analysis showed that the Ca/Si ratio of the C-(A)-S-H gel was minimized, leading to a denser microstructure and better binding ability under this mixing proportion. Therefore, this study may provide novel binder materials with a high proportion of CKD under ambient conditions. [ABSTRACT FROM AUTHOR]

Nitrogen oxide emissions have attracted much attention due to their impact on the atmospheric environment and human health. Combined with NO removal in the cement production process, coal gasification slag was used to prepare denitrification materials to decompose NO in cement kilns without the addition of reducing agents. Denitrification materials were synthesized by a chemical precipitation method at different pH. The denitrification mechanism was proposed in this study. The results indicated that the denitrification material prepared at a pH of 7 exhibited the best denitrification performance. The NO decomposition rate first increased and then decreased below 400°C, and then increased as the temperature increased, reaching over 97% above 700°C. In the low-temperature range, Fe(II) was assumed to be active species, and the absorbed NO on the Fe(II) site obtained an electron, which promoted the decomposition of NO. In the high-temperature range, besides the active element Fe, the residual carbon in the coal gasification slag was prone to oxidation-reduction reactions, reducing nitric oxide to nitrogen. A new waste-to-value concept is introduced in this study, which promotes green technology for sustainable development. [ABSTRACT FROM AUTHOR]

Environmental issues, such as global warming and pollution, could be solved by reducing the carbon dioxide (CO2) footprint on the surrounding atmosphere. Utilizing by-products as a cement substitute in cement production, such as cement kiln dust (CKD), could reduce CO2 emissions from burning raw materials in cement plants. This study investigated the effect of cement kiln dust on cement mortar's physical, flow, and mechanical properties. Cement was replaced with CKD up to 100% (by weight of dry cement). The optimum content of CKD was determined based on compressive strength; loss on ignition (LOI); and chloride (Cl), sulfate (SO3), and magnesium oxide (MgO) contents. Standard sand with a maximum diameter of 2 mm was used in this study, with a sand-to-binder ratio (s/b) of 3∶1. Three different models—multiexpression programming (MEP), nonlinear regression (NLR), and an artificial neural network (ANN)—were employed for estimating the compressive strength of CKD-modified cement mortar using the present study data (110 data sets) and 152 data collected from other research studies. The compressive strength of cement mortar was predicted as a function of water-to-binder ratio (w/b), sand-to-binder ratio, cement kiln dust content, silicon dioxide content in the binder, calcium oxide content in the binder, the maximum aggregate diameter (MDA), and curing ages (t). Based on the statistical assessments, the ANN models outperformed the MEP and NLR models in the testing phase. According to the sensitivity analysis, curing time is the most critical parameter affecting the compressive strength of CKD-modified cement mortar, and the SiO2 content percentage affected the compressive strength more than did the CaO content percentage. [ABSTRACT FROM AUTHOR]

In the new, dry-process method of cement production, the temperature of cement rotary kiln sintering zone is a key factor in ensuring the quality of cement clinker. Based on the auto-regressive with extra inputs model, a finite control set model predictive control with soft constraint of the generalized triangular interval is proposed in this paper for the characteristics of a cement rotary kiln calcination system with multi-variable, multi-time delay, bounded disturbance, and slow dynamic process. Simulation experiments show that the steady-state error of the control algorithm proposed in this paper is smaller with better anti-disturbance performance than that of the traditional reference-trajectory-constrained, predictive control algorithm. [ABSTRACT FROM AUTHOR]

This paper explores the energy-intensive cement industry, focusing on a plant in Greece and its mill and kiln unit. The data utilized include manipulated, non-manipulated, and uncontrolled variables. The non-manipulated variables are computed based on the machine learning (ML) models and selected by the minimum value of the normalized root mean square error (NRMSE) across nine (9) methods. In case the distribution of the data displayed in the user interface changes, the user should trigger the retrain of the AI models to ensure their accuracy and robustness. To form the objective function, the expert user should define the desired weight for each manipulated or non-manipulated variable through the user interface (UI), along with its corresponding constraints or target value. The user selects the variables involved in the objective function based on the optimization strategy, and the evaluation is based on the comparison of the optimized and the active value of the objective function. The differential evolution (DE) method optimizes the objective function that is formed by the linear combination of the selected variables. The results indicate that using DE improves the operation of both the cement mill and kiln, yielding a lower objective function value compared to the current values. [ABSTRACT FROM AUTHOR]

Cement production in the world market is steadily increasing. In 2000, it was 1600 million tons, while as of 2013, the annual amount exceeded 4000 million tons. The burning of cement clinker is associated with the generation of waste. It is estimated that the amount of cement kiln dust (CKD), during combustion, reaches about 15–20%, which means 700 million tons per year. However, not all types of by-products are reusable due to high alkali, sulfate, and chloride contents, which can adversely affect the environment. One environmentally friendly solution may be to use CKD in the production of high-performance concrete (HPC), as a substitute for some of the cement. This paper presents a study of the short- and long-term physical and mechanical properties of HPC with 5%, 10%, 15%, and 20% CKD additives. The experiments determined density, water absorption, porosity, splitting tensile strength, compressive strength, modulus of elasticity, ultrasonic pulse velocity, and evaluated the microstructure of the concrete. The addition of CKD up to 10% caused an increase in the 28- and 730-day compressive strengths, while the values decreased slightly when CKD concentration increased to 20%. Splitting tensile strength decreased proportionally with 5–20% amounts of CKD regardless of HPC age. Porosity, absorbability, and ultrasonic pulse velocity decreased with increasing cement dust, while the bulk density increased for HPC with CKD. Microstructure analyses showed a decrease in the content of calcium silicate hydrate (C–S–H), acceleration of setting, and formation of wider microcracks with an increase in CKD. From the results, it was shown that a 15% percentage addition of CKD can effectively replace cement in the production of HPC and contribute to reducing the amount of by-product from the burning of cement clinker. [ABSTRACT FROM AUTHOR]

High-spatial-resolution NO 2 vertical column densities (VCDs) were retrieved from airborne observations using the low-cost hyperspectral imaging sensor (HIS) at three industrial areas (i.e., Chungnam, Jecheon, and Pohang) in South Korea, where point sources (i.e., power plant, petrochemical complex, steel yard, and cement kiln) with significant NO 2 emissions are located. An innovative and versatile approach for NO 2 VCD retrieval, hereafter referred to as the modified wavelength pair (MWP) method, was developed to overcome the excessively variable radiometric and spectral characteristics of the HIS attributed to the absence of temperature control during the flight. The newly developed MWP method was designed to be insensitive to broadband spectral features, including the spectral dependency of surface and aerosol reflectivity, and can be applied to observations with relatively low spectral resolutions. Moreover, the MWP method can be implemented without requiring precise radiometric calibration of the instrument (i.e., HIS) by utilizing clean-pixel data for non-uniformity corrections and is also less sensitive to the optical properties of the instrument and offers computational cost competitiveness. In the experimental flights using the HIS, NO 2 plumes emitted from steel yards were particularly conspicuous among the various NO 2 point sources, with peak NO 2 VCDs of 2.0 DU (Dobson unit) at Chungnam and 1.8 DU at Pohang. Typical NO 2 VCD uncertainties ranged between 0.025–0.075 DU over the land surface and 0.10–0.15 DU over the ocean surface, and the discrepancy can be attributable to the lower signal-to-noise ratio over the ocean and higher sensitivity of the MWP method to surface reflectance uncertainties under low-albedo conditions. The NO 2 VCDs retrieved from the HIS with the MWP method showed a good correlation with the collocated Tropospheric Monitoring Instrument (TROPOMI) data (r=0.73 , mean absolute error equals 0.106 DU). However, the temporal disparities between the HIS frames and the TROPOMI overpass, their spatial mismatch, and their different observation geometries could limit the correlation. The comparison of TROPOMI and HIS NO 2 VCDs further demonstrated that the satellite sub-grid variability could be intensified near the point sources, with more than a 3-fold increase in HIS NO 2 VCD variability (e.g., difference between 25th and 75th quantiles) over the TROPOMI footprints with NO 2 VCD values exceeding 0.8 DU compared to footprints with NO 2 VCD values below 0.6 DU. [ABSTRACT FROM AUTHOR]

In cement industry, the selection of catalyst temperature window and the inhibition effect of dust composition in flue gas on catalyst are the key issues of flue gas denitrification. In this article, a pilot study with Ce doped V-W/Ti catalyst on the removal of NOx by selective catalytic reduction with ammonia (NH3-SCR) from the cement kiln flue gas was presented. Cement kiln dust loading on catalysts obviously decreased the NO conversion in the absence of SO2 and H2O, while the denitration efficiency restored from 75 to 98% at 280 ℃ after SO2 and H2O introduced into the reaction system, which mainly because the SO2 may enhance the acidic site on the catalyst surface, and prefer to be bonded with the coordinated Ca species, releasing the active sites poisoned by dust. The NH3-temperature programmed desorption (NH3-TPD), X-ray photoelectron spectroscopy (XPS), and H2-temperature programmed reduction (H2-TPR) detections were performed to reveal that the appropriate Ce and W ratios catalyst contributed better denitrification activity. The optimum ratio of Ce doped catalyst was amplified to form the standard honeycomb monomer catalyst, and then, the activity of catalyst was verified on the side line of cement kiln. The effect of temperature and space velocity on denitrification efficiency was investigated, and the denitration efficiency reached to 92.5% at 300℃ and 3000 h−1 space velocity. Moreover, the life of catalyst was verified and predicted by GM (1,1) grey model. The study realized the innovation from the laboratory data rules to the industrial pilot application, providing positive promoting value for the industrial large-scale demonstration application of the catalyst. [ABSTRACT FROM AUTHOR]

The use of high-temperature X-ray diffraction (HT-XRD) to study the mass transfer of raw meal constituents towards forming clinker phases and the occurrence of free lime (calcium oxide), also known as burnability, was assessed. A measuring strategy with temperature ranging from 1000°C to 1450°C was developed and compared with a conventional burnability method. The free lime determined by the methods showed that HT-XRD produced good results for the evaluation of burnability. In addition, HT-XRD revealed the formation of intermediate phases, providing insight into early reactions in a cement kiln. The particle size of quartz was found to affect crystal expansion of the phase at a high temperature, subsequently affecting the formation of silica polymorphs. The different raw meals used in this study also indicate that the formation of different silica polymorphs affects the formation of C2S. The lack of knowledge regarding the influence of β-quartz on the reduction of free lime is highlighted. [ABSTRACT FROM AUTHOR]

This research paper gives the development data obtained for modern modified periclase‐spinel materials that have an increased adaptive ability to preserve the material integrity and the operational reliability of the refractories exposed to the effect of the sign‐alternating high‐gradient and thermal loads. Based on the research done, a concept was developed to improve the heat resistance of the periclase‐spinel materials and it includes both the known mechanisms of absorbing excess energy by cracks that are developed under the action of thermal shocks (in particular, the effect of heterophasicity and creation of a microcracked structure due to the difference in thermal efficiency coefficients (TEC) for different phases) and new mechanisms of the structure‐&‐phase adaptations preserving simultaneously the integrity of modified periclase‐spinel refractories. The use of the developed modified periclase‐spinel refractories results in the energy saving of up to 15 %, reduction of material costs due to the extension of the service life of the lining elements of rotary kilns; reduction of the resources required for the maintenance and an increase in the amount of overhaul sessions. [ABSTRACT FROM AUTHOR]

The cement industry is the second largest source of global man-made CO2 emissions after the power industry, and the adoption of O2/CO2 combustion technology for cement kilns is of great significance in reducing CO2 emissions. In this paper, the effects of pulverized coal mixed air combustion and pulverized coal mixed O2/CO2 combustion on the velocity field, temperature field, CO2 and NOx concentration distribution in rotary kiln were investigated by CFD technique. The results showed that there is no difference in the velocity distribution between the two atmospheres, and the speed difference between the primary and secondary air creates a re-circulation zone near the burner. The O2/CO2 atmosphere combustion decreased the maximum temperature, but improved the uniformity of the temperature field. The pulverized coal burnout rate under O2/CO2 atmosphere decreased by 3.55% compared to O2/N2 atmosphere. The mole fraction of CO2 at the rotary kiln outlet is 0.08 and 0.93 for O2/N2 and O2/CO2 combustion atmospheres, respectively. It is easier to achieve CO2 aggregation and capture under O2/CO2 atmosphere than under O2/N2. The NOx concentration at O2/CO2 is approximately one half of that at O2/N2, which can save the investment on denitrification equipment. The simulation results reasonably agree with the measured data. The findings of this work will provide a reference for the generalization and application of the O2/CO2 flue gas cycle calcinating cement technology. [ABSTRACT FROM AUTHOR]

Collaborative disposal of sludge has been applied extensively in cement industry kilns, but the influence of organic components in sludge on the selective non-catalytic reduction (SNCR) denitrification is still in highly demanding. This paper focuses the influence of ethanol, n-octane, benzene, and acetone on the SNCR denitrification, and the influence of ethanol are analyzed on SNCR denitrification under different flue gas condition. The result showed that the presence of organic components reduces the reaction temperature of SNCR. When the temperature of SNCR reaction is at 750 ~ 800 ℃, the denitrification rate of four organic components is ethanol > benzene > n-octane > acetone. The optimum denitrification rate on SNCR can reach as high as 90.377% when the reaction condition is the NH3/NO is 1; the ethanol concentration is 1000 ppm; O2 concentration is 2%; and temperature is 750 ℃. The presence of carbon dioxide inhibits the denitrification reaction. With the increase of temperature, the influence of SO2 on the denitrification reaction first increases and then decreases. In this paper, the influence of organic components in sludge on SNCR denitrification will be analyzed, which provides a theoretical basis for the selection of sludge dosing method for cement kiln collaborative disposal. [ABSTRACT FROM AUTHOR]

Waste-to-energy is one of the most effective methods to save energy and reduce carbon emissions in the cement industry. In this study, a novel process of CO 2 reduction coupled with municipal solid waste gasification by recycling flue gas during co-disposal in cement kiln is proposed. The model of MSW gasification by recycling flue gas is developed in Aspen Plus based on Gibbs free energy minimization. Meanwhile, the techno-economic-environmental analysis of the proposed process is also evaluated via taking clinker production capacity of 5000 tones/day as the objective. Results indicate that the low heating value of syngas, the cold gasification efficiency, and total exergy efficiency are respectively 4.42 MJ/m3, 91.96%, and 82.33%, indicating a high energy conversion efficiency is obtained during MSW gasification by recycling flue gas from cement kiln. Moreover, the net present value, internal rate of return, and payback period of the proposed process are in sequence as 86.73 M$, 82.21%, and 2.67 years, assuming the coal price is 150 $/ton. The proposed process can reduce about 172.11 kg eq.CO 2 /ton clinker compared to the traditional cement clinker generation. • MSW gasification by recycling flue gas during co-disposal of cement kiln is proposed. • 82.33% of energy efficiency for MSW gasification is obtained during co-disposal in cement kiln. • The NPV, IRR and PBR of the proposed process are in sequence as 86.73 M$, 82.21% and 2.67 years. • The proposed process can reduce about 172.11 kg eq.CO 2 /ton clinker. [ABSTRACT FROM AUTHOR]

A cement rotary kiln is the main part of the cement production process, which has always attracted many researchers attention. However, this complex nonlinear system has not been modeled efficiently, which can make an appropriate performance, especially in noisy condition. In this work, the type 2 Takagi-Sugeno neuro-fuzzy system (T2TSNFS) is used to identify the cement rotary kiln, and the gradient descent (GD) algorithm is applied for tuning the parameters of antecedent and consequent parts of fuzzy rules. In addition, the optimal inputs of the system are selected by the genetic algorithm (GA) to achieve less complexity in the fuzzy system. The data relating to the Saveh White Cement (SWC) factory is used in the simulations. The results demonstrate that the proposed identifier has an appropriate performance in noisy conditions. Furthermore, in this work, T2TSNFS is evaluated in noisy conditions, which had not been worked out before in related research works. Also, T2TSNFS and type 1 Takagi-Sugeno neuro-fuzzy system (T1TSNFS) are compared. The simulations show that T2TSNFS has more proper performance when the standard deviation of noise increases. [ABSTRACT FROM AUTHOR]

Effective use of natural materials and industrial by products has a direct impact on economy, sustainable environment, and waste management. Poorly graded desert sand (SP) is widely observed in sand dunes and sand seas. Studies were performed to get beneficial use of cement kiln dust (CKD) in soil improvement. But there is a lack of information concerning using of CKD as an improving material for poorly graded sand with the aid of salt water. Salt water is widely available in Egypt from seas and some deep wells, using it will help in saving drink water which suffers from shortage in many countries. The aim of this research is to study the possibility of improving SP using CKD and salt water to be used in backfilling work and subbase layers of roads and pavements. Mixtures of poorly graded sand and various CKD ratios (10%, 20% and 30%) were classified and tested using grain size distribution, compaction, shear strength and California bearing tests. The results were compared with potable water. The results show that adding CKD improves the characteristic properties of SP even with salt water. The study enhances the using of 20% CKD with optimum water content of 9.12% of salt water to have noticeable improvement for SP and to be used efficiently in backfilling and subbase layers. [ABSTRACT FROM AUTHOR]

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Copyright of Clean Coal Technology is the property of Clean Coal Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Regenerated magnesia-calcium brick samples with different aluminium oxide (Al2O3) contents were prepared using spent magnesia-calcium bricks and fused magnesia as the main raw materials and Al2O3 powders as the additive. The phase compositions, microstructures, room temperature, hot flexural strength, and kiln coating adherence of the regenerated samples were investigated. This indicates that the Al2O3 content increased, mainly resulting in the content of tetracalcium aluminoferrite (C4AF) and tricalcium aluminate (C3A) increasing in the regenerated samples. The bulk density, room temperature flexural strength, and kiln coating adherence all increased, whereas the hot flexural strength and corrosion resistance to cement clinker both deteriorated with an increase in the Al2O3 content. This was because, on the one hand, the low melting point phases of C4AF and C3A improved the sinterability of the regenerated samples during the burning stage, and on the other hand, they melted or existed in the liquid phase at the experimental temperature, which degraded the hot flexural strength and corrosion resistance but enhanced the kiln coating adherence as the wettability of the liquid phase. The content of Al2O3 in the regenerated magnesia-calcium brick should not be higher than 1.1 wt.%, considering its comprehensive performance for cement rotary kiln. [ABSTRACT FROM AUTHOR]

NOx emission from the cement industry have received much attention. In order to reduce the NOx emission in cement kilns, nickel slag was used to prepare the non-ammonia denitrification material, and a denitrification mechanism was proposed in this study. The results showed that the denitrification material prepared at pH 7 exhibited the best denitrification performance. At low temperature, the highest denitrification performance was achieved between 200 and 300 °C with a NO decomposition rate of approximately 40%. Then, the NO decomposition rate increased as the temperature increased, reaching over 95% above 700 °C. The physicochemical characteristics showed that the material had the highest specific surface area and the highest relative Fe content, which benefited the denitrification performance. The divalent iron of the denitrification material was considered the active site for the reaction, and trivalent iron was not conducive to denitrification performance at a low temperature range. After the denitrification reaction, the Fe3+/Fe2+ increased from 0.89 to 1.31. The proposed denitrification mechanism was the redox process between divalent iron and trivalent iron. This study not only recycles industrial waste to reduce solid waste pollution but also efficiently removes nitrogen oxides from cement kilns without ammonia. [ABSTRACT FROM AUTHOR]

The research objective is to study the potential use of cement kiln dust to advance the engineering characteristics of black cotton soil (BCS) in India, which covers about 20% of the country's surface area. Cement kiln dust is an industrial waste that is difficult to dispose of and poses environmental risks, and the demand for cement is growing globally. The study aims to use laboratory tests to assess the impact of lime and cement kiln dust on the strength properties of BCS and to mitigate the excessive heave associated with the soil. The research methodology involves conducting Atterberg limit, free swell, compaction, and unconfined compression strength tests on BCS specimens treated with lime in incremental orders of 2% up to 10% of the dry weight of the soil sample. The optimum percentage of lime treated BCS sample treated with CKD in incremental order of 5% to 20% of dry mass of sample. 6% lime content was considered to be the optimum dosage with maximum UCS value for 7, 14 and 60 days and further on addition of CKD to lime treated BCS 6%lime + 15% CKD was found to be the optimum dosage with maximum UCS value for 7, 14 and 60 days. [ABSTRACT FROM AUTHOR]

The disposal of solid waste in dumpsites is getting increased in developing countries due to rapid urbanization. Biomining is an innovative idea to recover valuable resources from legacy waste and usable land from old dumpsites. Various mechanical equipments are employed in the biomining process, out of which the trommel screen plays a major role in sieving the legacy waste into different fractions. Optimization of trommel screen performance in the biomining process is carried out in this project. Feasible operating parameters such as the feed rate of the trommel screen 1 (100 mm) and trommel screen 2 (4 mm) and moisture content of legacy waste were optimized in the Rajapalayam biomining site, Tamil Nadu, India. The characteristics of legacy waste in three different biomining sites, namely, Rajapalayam, Srivilliputhur, and Sivakasi, were analyzed. Results indicate that 9 and 2 m3 h–1 feed rates show more separation efficiency for trommel 1 and 2, respectively. Changing the feed rates to the optimized values is also suggested to get better separating efficiency without compromising the purity and recovery of fractions. The recovery of the underflow fraction is maximum at a moisture content of 1.5% and 5.3% for trommel 1 and trommel 2, respectively. The trommel screen gets clogged for higher and lower values of moisture content so that the recovery of the underflow fraction gets affected. The refuse‐derived fuel (RDF) characteristics meet the standard for reuse in cement kilns, and the bioearth characteristics are not suitable to be used as a soil amendment in its original form due to the unavailability of nutrients such as NPK and elevated C/N ratio. [ABSTRACT FROM AUTHOR]

The high spatial resolution NO2 vertical column densities (VCDs) were measured from the airborne observations using the low-cost Hyperspectral Imaging Sensor (HIS) at three industrial areas (i.e., Chungnam, Jecheon, and Pohang) in Korea, where point sources (i.e., power plant, petrochemical complex, steel yard, and cement Kiln) with significant NO2 emissions are located. An innovative and versatile approach for NO2 VCD retrieval, hereafter referred to as the Modified Wavelength Pair (MWP) method, was developed to overcome the excessively variable radiometric and spectral characteristics of the HIS attributed to the absence of temperature control during the flight. The newly developed MWP method was designed to be insensitive to broadband spectral features, including the spectral dependency of surface and aerosol reflectivity, and can be applied to observations with relatively low spectral resolutions. Moreover, the MWP method can be implemented without requiring precise radiometric calibration of the instrument (i.e., HIS) by utilizing clean pixel data for non-uniformity corrections and is also less sensitive to the optical properties of the instrument and offers computational cost competitiveness. In the experimental flights using the HIS, NO2 plumes emitted from steel yards were particularly conspicuous among the various NO2 point sources, with peak NO2 VCD of 2.0 DU at Chungnam and 1.8 DU at Pohang. The typical NO2 VCD uncertainties ranged between 0.025-0.075 DU over the land surface and 0.10-0.15 DU over the ocean surface, and the discrepancy can be attributable to the lower signal-to-noise ratio over the ocean and higher sensitivity of the MWP method to surface reflectance uncertainties under low-albedo conditions. The NO2 VCDs retrieved from the HIS with the MWP method showed a good correlation with the collocated TROPOMI data (R=0.73, mean absolute error=0.106 DU). However, the temporal disparities between the HIS frames and the TROPOMI overpass, as well as the different observation geometries under complex vertical wind fields, limited the correlation. The comparison of TROPOMI and HIS NO2 VCD further demonstrated that the satellite sub-grid variability could be intensified near the point sources, with more than a threefold increase in HIS NO2 VCD variability (e. g., difference between 25th and 75th quantiles) over the TROPOMI footprints with NO2 VCD values exceeding 0.8 DU compared to footprints with NO2 VCD values below 0.6 DU. [ABSTRACT FROM AUTHOR]

The high spatial resolution NO2 vertical column densities (VCDs) were measured from the airborne observations using the low-cost Hyperspectral Imaging Sensor (HIS) at three industrial areas (i.e., Chungnam, Jecheon, and Pohang) in Korea, where point sources (i.e., power plant, petrochemical complex, steel yard, and cement Kiln) with significant NO2 emissions are located. An innovative and versatile approach for NO2 VCD retrieval, hereafter referred to as the Modified Wavelength Pair (MWP) method, was developed to overcome the excessively variable radiometric and spectral characteristics of the HIS attributed to the absence of temperature control during the flight. The newly developed MWP method was designed to be insensitive to broadband spectral features, including the spectral dependency of surface and aerosol reflectivity, and can be applied to observations with relatively low spectral resolutions. Moreover, the MWP method can be implemented without requiring precise radiometric calibration of the instrument (i.e., HIS) by utilizing clean pixel data for non-uniformity corrections and is also less sensitive to the optical properties of the instrument and offers computational cost competitiveness. In the experimental flights using the HIS, NO2 plumes emitted from steel yards were particularly conspicuous among the various NO2 point sources, with peak NO2 VCD of 2.0 DU at Chungnam and 1.8 DU at Pohang. The typical NO2 VCD uncertainties ranged between 0.025–0.075 DU over the land surface and 0.10–0.15 DU over the ocean surface, and the discrepancy can be attributable to the lower signal-to-noise ratio over the ocean and higher sensitivity of the MWP method to surface reflectance uncertainties under low-albedo conditions. The NO2 VCDs retrieved from the HIS with the MWP method showed a good correlation with the collocated TROPOMI data (R=0.73, mean absolute error=0.106 DU). However, the temporal disparities between the HIS frames and the TROPOMI overpass, as well as the different observation geometries under complex vertical wind fields, limited the correlation. The comparison of TROPOMI and HIS NO2 VCD further demonstrated that the satellite sub-grid variability could be intensified near the point sources, with more than a threefold increase in HIS NO2 VCD variability (e. g., difference between 25th and 75th quantiles) over the TROPOMI footprints with NO2 VCD values exceeding 0.8 DU compared to footprints with NO2 VCD values below 0.6 DU. [ABSTRACT FROM AUTHOR]

This study investigated the impact of substituting ordinary sand with cement kiln dust (CKD) as sand on the rheological, mechanical characteristics and some aspects of durability of sand concrete, formulated according to the experimental method of SABLOCRETE. Concrete mixtures were prepared with different CKD replacement rates: 0%, 5%, 10%, 15%, and 20%, while the quantities of cement, water, limestone fines, and adjuvant still constant. Different concrete mixtures were tested to measure: density, workability, air content, compressive and flexural strengths. Moreover, capillarity and immersion tests were performed to evaluate water absorption, and resistance to sulfuric acid exposure was assessed to estimate chemical durability. Results demonstrate that substitution rates had a significant influence on the properties of sand concrete. The optimal mechanical performance was around 15% of CKD sand. In contrast, the highest water absorption rates (both by immersion and capillarity), were observed in the concrete with 20% of CKD sand. However, the mass loss due to sulfuric acid, was lower in concrete containing 10% CKD sand. This investigation underlined the role of CKD's proportion in determining the mechanical and durability characteristics of sand concrete, offering valuable insights for sustainable construction practices. [ABSTRACT FROM AUTHOR]

In this study, a kind of CexFeyOz composite with oxygen vacancy structure and strong oxygen storage capacity was prepared by coprecipitation method. Under the condition of no HCl of flue gas, the Hg0 in the flue gas of cement kiln was efficiently and economically removed by using 6–8% oxygen. The results showed that the optimum preparation conditions of the catalyst were Ce-Fe molar ratio of 1–11 and calcination temperature of 550 °C. In addition, the reaction temperature, space velocity, the concentration of O2, SO2, and NO had significant effects on the removal efficiency of Hg0 at different rates. More precisely, at the reaction temperature of 350 °C, low airspeed, high concentration of O2, and low concentration of SO2 and NO, the efficiency reached the highest value. According to XPS results, the elemental valence of the CexFeyOz composite changed after the reaction. The redox pairs of Ce3+-Ce4+ and Fe3+-Fe2+ had the ability to transfer electrons, which enabled more oxygen adsorbed on the catalyst surface to be converted into O2−, leading to the improvement of the oxidation efficiency of Hg0. [ABSTRACT FROM AUTHOR]

Contamination of aquatic ecosystems with radioactive nuclides is significantly threaten the human body. So, finding effective and economical sorbents is significant for uranium elimination from an aqueous solution is important. In this study, Cement kiln dust (CKD) is a solid waste produced during the cement production process was utilized as sorbent for the uranium sorption from an aqueous solution. The maximum adsorption of 156.2 mg g−1 at pH 3.0 which reflects good sorption properties for the CKD. All in all, the displayed data declares that the CKD material possess an extraordinary tendency for U(VI) recovery from aquatic environments. [ABSTRACT FROM AUTHOR]

Digitalizing cement production plants to improve operation parameters' control might reduce energy consumption and increase process sustainabilities. Cement production plants are one of the extremest CO2 emissions, and the rotary kiln is a cement plant's most energy-consuming and energy-wasting unit. Thus, enhancing its operation assessments adsorb attention. Since many factors would affect the clinker production quality and rotary kiln efficiency, controlling those variables is beyond operator capabilities. Constructing a conscious-lab "CL" (developing an explainable artificial intelligence "EAI" model based on the industrial operating dataset) can potentially tackle those critical issues, reduce laboratory costs, save time, improve process maintenance and help for better training operators. As a novel approach, this investigation examined extreme gradient boosting (XGBoost) coupled with SHAP (SHapley Additive exPlanations) "SHAP-XGBoost" for the modeling and prediction of the rotary kiln factors (feed rate and induced draft fan current) based on over 3,000 records collected from the Ilam cement plant. SHAP illustrated the relationships between each record and variables with the rotary kiln factors, demonstrated their correlation magnitude, and ranked them based on their importance. XGBoost accurately (R-square 0.96) could predict the rotary kiln factors where results showed higher exactness than typical EAI models. [ABSTRACT FROM AUTHOR]

• This review focuses on the cement SCR catalyst of Ca and heavy metal poisoning • This review summarizes the research progress concerning the poisoning mechanism • This review listed five efficient ways to improve the antipoisoning performance • Future research directions for SCR catalysts in cement industry are discussed After the ultralow emission transformation of coal-fired power plants, cement production became China's leading industrial emission source of nitrogen oxides. Flue gas dust contents at the outlet of cement kiln preheaters were as high as 80–100 g/m3, and the calcium oxide content in the dust exceeded 60%. Commercial V 2 O 5 (-WO 3)/TiO 2 catalysts suitable for coal-fired flue gas suffer from alkaline earth metal Ca poisoning of cement kiln flue gas. Recent studies have also identified the poisoning of cement kiln selective catalytic reaction (SCR) catalysts by the heavy metals lead and thallium. Investigation of the poisoning process is the primary basis for analyzing the catalytic lifetime. This review summarizes and analyzes the SCR catalytic mechanism and chronicles the research progress concerning this poisoning mechanism. Based on the catalytic and toxification mechanisms, it can be inferred that improving the anti-poisoning performance of a catalyst enhances its acidity, surface redox performance-active catalytic sites, and shell layer protection. The data provide support in guiding engineering practice and reducing operating costs of SCR plants. Finally, future research directions for SCR denitrification catalysts in the cement industry are discussed. This study provides critical support for the development and optimization of poisoning-resistant SCR denitrification catalysts. [ABSTRACT FROM AUTHOR]

Since the cement industry acts as a significant contributor to carbon emissions in China, China's national emission trading system has announced that it should be included in the system soon. However, current cement carbon accounting methods require high-resolution data from various processes on the production line, making it a cumbersome and costly process. To address this issue, this study explores the feasibility and reliability of using machine learning algorithms to develop electricity–carbon models. These models estimate carbon emissions based solely on electricity data, enabling faster and more cost-effective accounting of carbon in cement production. This study investigates the correlations between electricity data and carbon emissions for a large cement manufacturer in southern China. It compares the performance of models based on the supply of electricity (purchased electricity and waste heat electricity) with those based on the consumption of electricity (electricity used on the grinding machines in the production lines) to identify the key factor for carbon emission calculations. The identified best performing model showed high accuracy, with an R2 of 0.96, an RMSPE of 3.88%, and a MAPE of 2.56%. Based on this, the novel electricity–carbon model has the potential to act as one of the optional methods for carbon emissions accounting in the cement industry and to support carbon emissions data promotion within China's national emission trading systems. [ABSTRACT FROM AUTHOR]

The carbonation of alkaline industrial wastes is a pressing issue that is aimed at reducing CO2 emissions while promoting a circular economy. In this study, we explored the direct aqueous carbonation of steel slag and cement kiln dust in a newly developed pressurized reactor that operated at 15 bar. The goal was to identify the optimal reaction conditions and the most promising by-products that can be reused in their carbonated form, particularly in the construction industry. We proposed a novel, synergistic strategy for managing industrial waste and reducing the use of virgin raw materials among industries located in Lombardy, Italy, specifically Bergamo–Brescia. Our initial findings are highly promising, with argon oxygen decarburization (AOD) slag and black slag (sample 3) producing the best results (70 g CO2/kg slag and 76 g CO2/kg slag, respectively) compared with the other samples. Cement kiln dust (CKD) yielded 48 g CO2/kg CKD. We showed that the high concentration of CaO in the waste facilitated carbonation, while the presence of Fe compounds in large amounts caused the material to be less soluble in water, affecting the homogeneity of the slurry. [ABSTRACT FROM AUTHOR]

Cement kiln dust (CKD) is a residue produced during the manufacture of cement that contains hazardous solid waste of high toxicity that affects the environment and public health. In this study, the possibility of using CKD as a filler in the plastic and rubber industry was studied. The effect of CKD concentration and gamma irradiation dose on the mechanical and physico-chemical properties of the composite containing waste polyethylene/devulcanized rubber/EPDM rubber (named blank) was investigated. Different concentrations of CKD, namely 10, 15, 20, and 30 phr (part per hundred part of composite), were used. The results indicated that this composite (blended with CKD) properties were improved. The most significant improvement was achieved by using CKD concentration of 20 phr at the dose of 100 kGy of gamma irradiation. These findings were demonstrated by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

The cement industry is one of the primary sources producing anthropogenic CO2 emissions. The significant increase in the demand for cement in years has significantly contributed to the increase in carbon emissions. Among numerous CO2 treatment technologies, calcium looping (CaL) is a practical approach to mitigating CO2 emissions. This paper used calcium looping (CaL) to capture CO2 from flue gas in a cement pre-calciner kiln system. The raw material exiting the lowest stage of the preheater is used as a calcium-based adsorbent, and the carbonation reactor is built between the tertiary and secondary preheaters, using the high-temperature flue gas exiting the tertiary preheater to provide heat for the reaction. The CFD (Computational Fluid Dynamics) simulation technology was used to evaluate the rationality of the carbonation reactor and the key factors affecting the carbon removal efficiency of the carbonation reactor. The results indicate that the velocity and pressure fields of the carbonation reactor conform to the general operating rules and are reasonable. The optimal operating speed of particles in the carbonation reactor is 15 m/s, with a separation efficiency of particles of 92.5%, ensuring the smooth discharge of reaction products. The factor analysis of the carbonation reactor shows that when the temperature is 911 K, the mass flow rate of CaO is 2.07 kg/s, and the volume fraction of CO2 is 0.28, the carbonation reaction reaches a chemical equilibrium state, and the carbon removal efficiency is 90%. It should be noted that this carbon removal efficiency is the optimal carbon removal efficiency based on a combination of economic factors. In addition, the influencing factors show a precise sequence: CO2 volume fraction > CaO addition amount > temperature. Finally, we investigated the impact of the addition of the carbonation reactor on the preheater system. The results show that adding the carbonation reactor causes an increase in the flue gas velocity at the outlet of the preheater and a decrease in pressure, reducing the separation efficiency. Although the separation efficiency decreases slightly, the impact on the pre-calciner system is minimal. [ABSTRACT FROM AUTHOR]