In the carbonate industry,deep decarbonization strategies are necessary to effectively remediate CO_(2).These strategies mainly include both sustainable energy supplies and the conversion of CO_(2)in downstream proces...In the carbonate industry,deep decarbonization strategies are necessary to effectively remediate CO_(2).These strategies mainly include both sustainable energy supplies and the conversion of CO_(2)in downstream processes.This study developed a coupled process of biomass chemical looping H2 production and reductive calcination of CaCO_(3).Firstly,a mass and energy balance of the coupled process was established in Aspen Plus.Following this,process optimization and energy integration were implemented to provide optimized operation conditions.Lastly,a life cycle assessment was carried out to assess the carbon footprint of the coupled process.Results reveal that the decomposition temperature of CaCO_(3)in an H_(2)atmosphere can be reduced to 780℃(generally around 900℃),and the conversion of CO_(2)from CaCO_(3)decomposition reached 81.33%with an H2:CO ratio of 2.49 in gaseous products.By optimizing systemic energy through heat integration,an energy efficiency of 86.30%was achieved.Additionally,the carbon footprint analysis revealed that the process with energy integration had a low global warming potential(GWP)of-2.624 kg·kg^(-1)(CO_(2)/CaO).Conclusively,this work performed a systematic analysis of introducing biomass-derived H_(2)into CaCO_(3)calcination and demonstrated the positive role of reductive calcination using green H_(2)in mitigating CO_(2)emissions within the carbonate industry.展开更多
The preparation of cementitious materials by replacing part of the cement with activated coal gangue is of great significance to the cement industry in terms of carbon reduction and coal-based solid waste utilization....The preparation of cementitious materials by replacing part of the cement with activated coal gangue is of great significance to the cement industry in terms of carbon reduction and coal-based solid waste utilization.For this paper,cementitious material was prepared by firing activated coal gangue under suspension conditions and batching it with limestone powder using Inner Mongolia coal gangue as raw material.The optimal ratio was determined by testing the strength changes of the cementitious material at 3,7,and 28 days of hydration,and the hydration process and mechanism were explored by combining the pore structure,heat of hydration,chemical composition,phase composition,and microscopic morphological characteristics of the hydration products.The results showed that the active materials formulated from activated gangue and limestone powder can be used to prepare cementitious materials with good performance at the level of 30%–50%replacement of cement.The optimal ratio was 30%replacement of cement,and the mass ratio of calcined gangue to limestone powder was 2:1.The 3 days compressive strength of this ratio was 28.8 MPa,which was only slightly lower than that of cement.However,the 28 days compressive strength of samples reached 67.5 MPa,which was much higher than that of the reference cement.In the hydration of this cementitious material,not only does the activated coal gangue react with the Ca(OH)_(2)formed by hydration to form C–S–H gel,but CaCO3 also participates in the reaction to form a new phase of carbon aluminate,and the two effects together promote the development of the later strength of the samples.This paper can provide a reference for carbon reduction in the cement production process and comprehensive utilization of coal gangue.展开更多
Montmorillonite and clinoptilolite zeolite were used as representative materials to prepare calcined clay-cement binary cementitious materials in order to study the effect of calcination treatment on the activation of...Montmorillonite and clinoptilolite zeolite were used as representative materials to prepare calcined clay-cement binary cementitious materials in order to study the effect of calcination treatment on the activation of clay minerals and the activity difference between layered and framed clays in this research.The influence of different calcined clay content(2%,4%,6%,8%,10%)on the fluidity,compressive strength,microstructure,phase change,and hydration heat of cement-based materials were analyzed.The calcined clay improves the fluidity of cement-based materials as compared with the uncalcined group.The addition of calcined montmorillonite(CMT)improves the development of mechanical strength,and the optimal compressive strength reaches 85 MPa at 28 days with 8%CMT.However,the activity of calcined clinoptilolite zeolite(CZL)is weak with few reaction sites,which slightly reduced the mechanical strength as compared to the blank sample.The addition of CMT changes the microscopic morphology of hydration products such as C-S-H and C-A-H,leading to the formation and transformation of ettringite in the early stage.It promotes the gradual polymerization of Si-O bonds into Si-O-Si bonds simultaneously,which accelerates the early hydration process.However,CZL acts mainly as a filling function in the cementitious system.In brief,CMT as an admixture can improve the mechanical properties of cement,but CZL has little effect.This work provides a guideline for the applications of calcined clay in cement,considering the influence of clay type on workability and mechanical strength.展开更多
The application of high-sulfur petroleum coke after desulfurization in aluminum electrolysis anodes is an important development trend. However, removing sulfur from high-sulfur petroleum coke is still a significant ch...The application of high-sulfur petroleum coke after desulfurization in aluminum electrolysis anodes is an important development trend. However, removing sulfur from high-sulfur petroleum coke is still a significant challenge.This study proposes alkali calcining and reflux washing to examine the impacts of temperature, particle size, the mass ratio of Na_(2)CO_(3) to NaOH, and total sodium addition on the desulfurization efficiency and mechanism. The results show that the desulfurization rate increases with increasing temperature, increasing total sodium content, and decreasing particle size. The addition of alkali can significantly reduce the opening-ring reaction temperature of thiophene and convert organic sulfur into inorganic sulfur(Na_(2)S). Three washing methods were compared, and reflux washing was selected to separate inorganic sulfur(Na_(2)S) from calcined petroleum coke. The sulfur content in petroleum coke decreased from 7.29% to 1.90%, with a desulfurization rate of 80.13% under optimal conditions. The petroleum coke was analyzed before and after desulfurization using X-Ray diffraction(XRD), Scanning Electron Microscopy(SEM), Infrared Spectroscopy(IR), Thermogravimetric Analysis and Differential Scanning Calorimetry(TG-DSC), Gaschromatography-mass Spectrometry(GC-MS). The results show that thiophene and benzothiophene in petroleum coke are decomposed and converted into octane and ethyl cyclohexane. These new observations are expected to provide further understanding and guidance for the utilization of highsulfur petroleum coke.展开更多
The world’s total fossil fuel consumption has been significantly increasing with consequential increased environmental catastrophes. A hunt for an alternate energy source was stimulated. Biofuel is a plausible option...The world’s total fossil fuel consumption has been significantly increasing with consequential increased environmental catastrophes. A hunt for an alternate energy source was stimulated. Biofuel is a plausible option in this pursuit due to its ideal qualities which included but are not limited to renewability and environmental friendliness. However, the pump price of biodiesel is still very high due mainly to the high cost of the production of the commodity which is influenced by the feedstock and the homogeneous nature of catalyst used. Heterogeneous catalyst was prepared by using Pila globosa sea snail shells prepared by calcination (CP8) and by acid activation (PTW1M). Hydnocapus weightiana seed oil (Non-edible feedstock) was extracted using the soxhlet extraction method and was used for biofuel production with a methanol oil ratio of 3:1. Agitation speed 800, 600 rmp, reaction temperatures of 70°C, 60°C, catalyst concentration (3.00, 2.00 wt%) and reaction time (70 and 60 min) was maintained for CP8 and PTW1M respectively. The rate of the reaction followed a reversible second-order reaction rate. Re-usability accessed. From TGA analysis, the best calcination temperature was 800°C. SEM results showed improved surface morphology after calcination, especially for CP8. FTIR analysis showed the elimination of volatiles and formation of CaO and CaO<sub>4</sub>Te after calcination. The reaction rate constant at different temperatures was 0.0287 at 30°C, 0.1200 at 50°C and 0.1142 at 70°C and activation energy of the ethyl ester was 49.49 KJ/mol. Using CP8. Most of the fuel properties met with ASTM 6751 standard. The result of the re-usability showed that the biodiesel yield declined as follows: 92, 86, 80, 73 and 69 % for CP8 and 85, 84, 81, 76, 65. For PTW1M. After the fifth regeneration cycle, both CP8 and PTW1M samples of Pila globosa sea snail shell catalyst proved effective in transesterification reaction of Hydnocapus weightiana seed oil using ethanol. It was observed that the calcined catalyst (CP8) showed a superior catalytic performance.展开更多
Ordinary Portland Cement (OPC) is by mass the largest manufactured product on Earth, responsible for approximately 6% - 8% of global anthropogenic carbon dioxide emissions (CO<sub>2</sub>) and 35% of indus...Ordinary Portland Cement (OPC) is by mass the largest manufactured product on Earth, responsible for approximately 6% - 8% of global anthropogenic carbon dioxide emissions (CO<sub>2</sub>) and 35% of industrial CO<sub>2</sub> emissions. On average 0.8 to 0.9 ton of CO<sub>2</sub> is emitted to produce one ton of OPC. In this paper, partial substitution of clinker (30% - 35%) by the calcined clay-limestone mixture was investigated in order to produce an eco-cement (LC3). Analyzes by XRF, XRD and ATG/ATD have characterized different components, determined the calcination temperature and selected the right clay which can act as effective Supplementary Cementitious Material (SCM). Mechanical tests on mortar carried out over a period of 90 days. The WBCSD/WRI “Greenhouse Gas Protocol” methodology then allowed the calculation of CO<sub>2</sub> emissions into the atmosphere. Three types of clay are available in the Songololo Region. The kaolinite is the principal clay mineral and its content varies from 27% to 34%. The sum of kaolinite and amorphous phase which enable clay to react with cementitious material ranges from 57% to 60%. The SiO<sub>2</sub> content ranges from 33% to 76%, the Alumina content from 12% to 20% so that the ratio Al<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> is on the higher side (0.17 - 0.53). The calcination window is between 750°C and 850°C and the best clay which can act as SCM identified. The clinker’s substitution reduced CO<sub>2</sub> emissions from 0.824 ton of CO<sub>2</sub> for one ton of OPC to 0.640 ton of CO<sub>2</sub> for one ton of LC3, means 22% less emissions. The compressive strengths developed by LC3 vary from 8.91 to 57.6 MPa (Day 1 to Day 90), exceed those of references 32.5 cement and are close to 42.5 cement. In view of the results, LC3 cement can be considered for industrial trials.展开更多
This paper presents a study of the potential use of iron mining tailings as artificial pozzolan (metakaolin) after their submission to thermal treatment via calcination in a flash furnace. The research consists of the...This paper presents a study of the potential use of iron mining tailings as artificial pozzolan (metakaolin) after their submission to thermal treatment via calcination in a flash furnace. The research consists of the characterization of the tailings before and after calcination, chemical, mineralogical, thermogravimetric, and mechanical strength analyses were conducted. The results were compared with those for commonly used pozzolans, metakaolin, and similarities were identified. The study of the morphology of the particles before and after calcination was conducted through analyses of images obtained by scanning electronic microscope. The pozzolanic activity of the fine mining tailings calcined with flash technology was evaluated in uniaxial compression trials, which showed excellent results.展开更多
As the coal combustion behaviors are rather complex in the cement industry, the traditional assessment method cannot be directly applied to evaluate the quality of coal. Based on the thermal analysis tests of more tha...As the coal combustion behaviors are rather complex in the cement industry, the traditional assessment method cannot be directly applied to evaluate the quality of coal. Based on the thermal analysis tests of more than 80 kinds of anthracite and bituminous coal, three evaluation parameters, namely, burning intensity (I), average capacity of heat release (Q), and general burning index (S) are presented, combining with the consideration of application and calciner types in the cement industry. Taking these three parameters into consideration together is necessary. Experimental results show that the coal with higher S, lower I and higher Q can be rated as the best for the calciner in the cement industry. The quantitative indexes are given to evaluate the bituminous coal and anthracite in this paper. This new assessment method has implications for the design of calciner in the cement industry.展开更多
A significant amount of aluminum dross is available as a waste in foundry industries in Bangladesh. In this study, alumina was ex- tracted from aluminum dross collected from two foundry industries situated in Dhamrai ...A significant amount of aluminum dross is available as a waste in foundry industries in Bangladesh. In this study, alumina was ex- tracted from aluminum dross collected from two foundry industries situated in Dhamrai and Manikgang, near the capital city, Dhaka. Alu- minum dross samples were found to approximately contain 75wt% A1203 and 12wt% SIO2. An acid dissolution process was used to recover the alumina value from the dross. The effects of various parameters, e.g., temperature, acid concentration, and leaching time, on the extrac- tion of alumina were studied to optimize the dissolution process. First, AI(OH)3 was produced in the form of a gel. Calcination of the AI(OH)3 gel at 1000℃, 1200℃, and 1400℃ for 2 h produced O-AlcOa, (t~+O)-A1203, and u-alumina powder, respectively. Thermal charac- terization of the AI(OH)3 gel was performed by thermogravimetric/differential thermal analysis (TG/DTA) and differential scanning calo- rimetry (DSC). The phases and crystallite size of the alumina were determined by X-ray diffraction analysis. The dimensions of the alumina were found to be on the nano level. The chemical compositions of the aluminum dross and alumina were determined by X-ray fluorescence (XRF) spectroscopy. The microstructure and morphology of the alumina were studied with scanning electron microscopy. The purity of the alumina extracted in this study was found to be 99.0%. Thus, it is expected that the obtained alumina powders can be potentially utilized as biomaterials.展开更多
A spherical-like Ni_(0.6)Co_(0.2)Mn_(0.2)(OH)_2 precursor was tuned homogeneously to synthesize LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 as a cathode material for lithium-ion batteries.The effects of calcination temperature on t...A spherical-like Ni_(0.6)Co_(0.2)Mn_(0.2)(OH)_2 precursor was tuned homogeneously to synthesize LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 as a cathode material for lithium-ion batteries.The effects of calcination temperature on the crystal structure,morphology,and the electrochemical performance of the as-prepared LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 were investigated in detail.The as-prepared material was characterized by X-ray diffraction,scanning electron microscopy,laser particle size analysis,charge–discharge tests,and cyclic voltammetry measurements.The results show that the spherical-like LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 material obtained by calcination at 900°C displayed the most significant layered structure among samples calcined at various temperatures,with a particle size of approximately 10 μm.It delivered an initial discharge capacity of 189.2 m Ah×g^(-1) at 0.2C with a capacity retention of 94.0% after 100 cycles between 2.7 and 4.3 V.The as-prepared cathode material also exhibited good rate performance,with a discharge capacity of 119.6 m Ah×g^(-1) at 5C.Furthermore,within the cut-off voltage ranges from 2.7 to 4.3,4.4,and 4.5 V,the initial discharge capacities of the calcined samples were 170.7,180.9,and 192.8 m Ah×g^(-1),respectively,at a rate of 1C.The corresponding retentions were 86.8%,80.3%,and 74.4% after 200 cycles,respectively.展开更多
Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried ...Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried out over coral reef-like Ni/Al2O3 catalysts in a continuous flow type fixed-bed reactor.The structure and properties of the fresh and used catalysts were studied by SEM,N2 adsorption-desorption,XRD,H2-TPR,O2-TPO,TG and ICP-AES techniques.The results showed that the coral reef-like Ni/Al2O3 catalysts exhibited better activity than the conventional Ni/Al2O3-H2O catalysts.The activities of coral reef-like catalysts were in the order of Ni/Al2O3-673Ni/Al2O3-573Ni/Al2O3- 473Ni/Al2O3-773.Ni/Al2O3-673-EG catalyst showed not only good activity and improved stability but also superior resistance to carbon deposition,sintering,and Ni loss.Under the reaction conditions of CO/H2(molar ratio)=1:3,593 K,atmospheric pressure and a GHSV of 2500 h-1,CH4 selectivity was 84.7%,and the CO conversion reached 98.2%.展开更多
Muscovite mineral was roasted in different conditions.Rubidium leaching rate was a standard to examine the impact of various factors on calcination effect,including the agent types,roasting time,mass ratio,and roastin...Muscovite mineral was roasted in different conditions.Rubidium leaching rate was a standard to examine the impact of various factors on calcination effect,including the agent types,roasting time,mass ratio,and roasting temperature.The results indicate that the best agent is the combination of sodium chloride and calcium chloride,and its mass ratio of muscovite/NaCl/CaCl2is1.00:0.25:0.25.Calcined at 850℃ for 30 min,the rubidium leaching rate is up to 90.12%.The reaction of muscovite ore with the chlorinating agent CaCl2was studied by TG/DSC,and the surface morphology before and after leaching was characterized by SEM.Rubidium chloride products can be obtained using t-BAMBP extraction,hydrochloric acid re-extraction,and purification.展开更多
Trace Na sources, extraction dynamics of trace Na, and influences of calcination temperature on quartz lattice, fluid inclusions, and muscovite were studied in detail herein for trace Na extraction from the quartz ore...Trace Na sources, extraction dynamics of trace Na, and influences of calcination temperature on quartz lattice, fluid inclusions, and muscovite were studied in detail herein for trace Na extraction from the quartz ore with water leaching at 90℃. Experimental results suggested that the trace Na sources included quartz lattice, fluid inclusions, and muscovite. The extraction rate of the trace Na in quartz ores can reach 31.0wt% after calcination at 900℃ for 5 h and water leaching at 90℃ for 24 h. The extraction process consisting of the dissolution of unfree Na and diffusion of free Na was dominated by calcination temperature. Calcination at 900℃ for 5 h was effective for extraction of the trace Na in fluid inclusions and muscovite. The extraction of the trace Na was mainly affected by the decrepitation of fluid inclusions when the calcination temperature ranged from 400 to 600℃ and by the damage of muscovite when the calcination temperature ranged from 600 to 900℃. Based on the extraction rates at different calcination temperatures, approximately 20.1wt% of the trace Na occurred in fluid inclusions, approximately 10.9wt% existed in muscovite, and 69.0wt% mainly occurred in quartz lattice.展开更多
Effects of different heat treatment temperatures on properties of Chinese calcined flint clay based plastic refractories were investigated using Chinese calcined flint clay as starting material, aluminum sulfate and f...Effects of different heat treatment temperatures on properties of Chinese calcined flint clay based plastic refractories were investigated using Chinese calcined flint clay as starting material, aluminum sulfate and fireclay as binding system. The results showed that with temperature rising, Chinese calcined flint clay based plastic refractories shrinked firstly and then expanded. The modulus of rupture (MOR) and the cold crushing strength (CCS) inereased firstly and then decreased from 110 ℃ to 600 ℃ , then increased obviously. Thermal expansion coefficient increased from 110 ℃ to 760 ℃, decreased from 760 ℃ to 1 300 ℃ , and increased from 1 300 ℃ to1500 ℃.展开更多
We aim in this research at synthesizing high-purity aluminium titanate with sludge from the aluminium profile factory by shock cooling method, and mainly discuss the effect of calcining reaction temperature and holdin...We aim in this research at synthesizing high-purity aluminium titanate with sludge from the aluminium profile factory by shock cooling method, and mainly discuss the effect of calcining reaction temperature and holding time on crystalline, microstructure and content of aluminum titanate materials to determine the preferred calcining temperature and holding time. XRD and SEM methods were utilized to characterize the crystalline and microstructure of each specimen, Rietveld Quantification software was used for the determination of different crystalline contents of specimens, and Philips plus software was applied to determine the cell parameters of aluminium titanate in different specimens. According to the experimental results, preferred calcining temperature is determined as 1400℃ and preferred holding time is 2 h, at which the grains of aluminum titanate grow completely and the purity of aluminum titanate is 97.2wt%.展开更多
Mullite and corundum co-bonded SiC-based composite ceramics(SiC-mullite-Al2O3)were prepared by using SiC,calcined bauxite and kaolin via pressureless carbon-buried sintering.The low-cost SiC-based composite ceramics d...Mullite and corundum co-bonded SiC-based composite ceramics(SiC-mullite-Al2O3)were prepared by using SiC,calcined bauxite and kaolin via pressureless carbon-buried sintering.The low-cost SiC-based composite ceramics designed in this study are expected to be used as thermal storage materials in solar thermal power generation based on the high density and excellent thermal shock resistance.The influences of calcined bauxite addition and sintering temperature on the microstructures,phase compositions,and physical properties of the samples were investigated.Results demonstrated that the introduction of calcined bauxite containing two bonding phases greatly reduced the lowest sintering temperature to 1400℃.The SiC-mullite Al2O3 composite with 40 wt%calcined bauxite sintered at 1500℃exhibited optimum performance.The density and bending strength were 2.27 g·cm^-3 and 77.05 MPa.The bending strength increased by 24.58%and no cracks were observed after 30 thermal shock cycles,while general clay would reduce the thermal shock resistance of SiC.The SiC-mullite-Al2O3 composites with satisfied performance are expected to be used as thermal storage materials in solar thermal power generation systems.展开更多
To enable the utilization of low-grade and high-sulfur bauxite, the suspension calcination was used to remove the sulfur and the activate silica minerals, and the calcinated bauxite was subjected to a desilication pro...To enable the utilization of low-grade and high-sulfur bauxite, the suspension calcination was used to remove the sulfur and the activate silica minerals, and the calcinated bauxite was subjected to a desilication process in Na OH solution under atmospheric pressure. The desulfurization and desilication properties and mineralogical evolution were studied by X-ray diffraction, thermogravimetry–differential thermal analysis, scanning electron microscopy, and FactSage methods. The results demonstrate that the suspension calcination method is efficient for sulfur removal: 84.21% of S was removed after calcination at 1000°C for 2 min. During the calcination process, diaspore and pyrite were transferred to α-Al2O3, magnetite, and hematite. The phase transformation of pyrite follows the order FeS2 → Fe3O4 → Fe2O3, and the iron oxides and silica were converted into iron silicate. In the alkali-soluble desilication process, the optimum condition was an alkali solution concentration of 110 g/L, a reaction time of 20 min, and a reaction temperature of 95°C. The corresponding desilication ratio and alumina loss ratio were 44.9% and 2.4%, respectively, and the alumina-to-silica mass ratio of the concentrate was 7.9. The Al2O3·2SiO2, SiO2, and Al2O3 formed during the calcination process could react with Na OH solution, and their activity decreased in the order of Al2O3·2 SiO2, SiO2, and Al2O3.展开更多
A series of x (Fe,Ni)/Al2O3 catalysts (x = 2-12 wt%) were prepared using incipient wetness method and studied for the conversion of synthesis gas to light olefins.6 wt%(Fe,Ni)/Al2O3 catalyst was found to be the ...A series of x (Fe,Ni)/Al2O3 catalysts (x = 2-12 wt%) were prepared using incipient wetness method and studied for the conversion of synthesis gas to light olefins.6 wt%(Fe,Ni)/Al2O3 catalyst was found to be the optimal catalyst for the production of C2-C4 olefins.The effects of calcination behaviors and operational conditions on the catalytic performance of the optimal catalyst were investigated.The best operational conditions were molar feed ratio H2/CO = 2/1,T = 260 ℃,gas hourly space velocity (GHSV) = 2600 h^-1 and the pressure of 3 bar.Character-izations of both precursors and catalysts were carried out using X-ray diffraction (XRD),temperature-programmed reduction (TPR),scanning electron microscopy (SEM),N2-adsorption-desorption measurement,thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC).展开更多
In this study,selective dealumination of Beta zeolites was performed through partially removing the templating agent in Beta zeolites by calcination and then removing the aluminum on the external surface of Beta zeoli...In this study,selective dealumination of Beta zeolites was performed through partially removing the templating agent in Beta zeolites by calcination and then removing the aluminum on the external surface of Beta zeolites with acid treatment.Hydrocracking catalysts were prepared by loading WO_(3)onto these dealuminated Beta zeolites.It was shown that the surface SiO_(2)/Al_(2)O_(3)of selectively dealuminated Beta zeolites was higher than that of conventionally dealuminated samples for the same bulk SiO_(2)/Al_(2)O_(3),and the hydrogenation activity of the catalyst of the selectively dealuminated Beta zeolites was lower than that of conventionally dealuminated Beta zeolites.The experimental results for tetralin hydrocracking to BTX showed that the catalysts based on the selectively dealuminated Beta zeolites had higher BTX selectivity and lower coke formation rate than that the catalysts based on the conventionally dealuminated Beta zeolites.展开更多
基金support from the National Natural Science Foundation of China(21978128,91934302)partial support from the State Key Laboratory of Materials-oriented Chemical Engineering(ZK202006)also acknowledged.Additionallysupported by the“Cultivation Program for The Excellent Doctoral Dissertation of Nanjing Tech University(3800124701)”.
文摘In the carbonate industry,deep decarbonization strategies are necessary to effectively remediate CO_(2).These strategies mainly include both sustainable energy supplies and the conversion of CO_(2)in downstream processes.This study developed a coupled process of biomass chemical looping H2 production and reductive calcination of CaCO_(3).Firstly,a mass and energy balance of the coupled process was established in Aspen Plus.Following this,process optimization and energy integration were implemented to provide optimized operation conditions.Lastly,a life cycle assessment was carried out to assess the carbon footprint of the coupled process.Results reveal that the decomposition temperature of CaCO_(3)in an H_(2)atmosphere can be reduced to 780℃(generally around 900℃),and the conversion of CO_(2)from CaCO_(3)decomposition reached 81.33%with an H2:CO ratio of 2.49 in gaseous products.By optimizing systemic energy through heat integration,an energy efficiency of 86.30%was achieved.Additionally,the carbon footprint analysis revealed that the process with energy integration had a low global warming potential(GWP)of-2.624 kg·kg^(-1)(CO_(2)/CaO).Conclusively,this work performed a systematic analysis of introducing biomass-derived H_(2)into CaCO_(3)calcination and demonstrated the positive role of reductive calcination using green H_(2)in mitigating CO_(2)emissions within the carbonate industry.
基金funded by the National Natural Science Foundation of China Projects(Grant No.51672207).
文摘The preparation of cementitious materials by replacing part of the cement with activated coal gangue is of great significance to the cement industry in terms of carbon reduction and coal-based solid waste utilization.For this paper,cementitious material was prepared by firing activated coal gangue under suspension conditions and batching it with limestone powder using Inner Mongolia coal gangue as raw material.The optimal ratio was determined by testing the strength changes of the cementitious material at 3,7,and 28 days of hydration,and the hydration process and mechanism were explored by combining the pore structure,heat of hydration,chemical composition,phase composition,and microscopic morphological characteristics of the hydration products.The results showed that the active materials formulated from activated gangue and limestone powder can be used to prepare cementitious materials with good performance at the level of 30%–50%replacement of cement.The optimal ratio was 30%replacement of cement,and the mass ratio of calcined gangue to limestone powder was 2:1.The 3 days compressive strength of this ratio was 28.8 MPa,which was only slightly lower than that of cement.However,the 28 days compressive strength of samples reached 67.5 MPa,which was much higher than that of the reference cement.In the hydration of this cementitious material,not only does the activated coal gangue react with the Ca(OH)_(2)formed by hydration to form C–S–H gel,but CaCO3 also participates in the reaction to form a new phase of carbon aluminate,and the two effects together promote the development of the later strength of the samples.This paper can provide a reference for carbon reduction in the cement production process and comprehensive utilization of coal gangue.
基金The research presented in this paper was supported by National Natural Science Foundation of China(Grant No.52272031)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan),and the Opening Fund of Guangxi Key Laboratory of New Energy and Building Energy Saving(Grant No.19-J-22-2)+3 种基金Key Research and Development Program of Hubei Province(Grant No.2020BAB065)Key Research and Development Program of Jiangxi Province(Grant No.20201BBG71011)Fundamental Research Funds for the Central Universities,CHD(Grant No.300102211506)Opening Fund of Key Laboratory of Advanced Building Materials of Anhui Province(Grant No.JZCL001KF).
文摘Montmorillonite and clinoptilolite zeolite were used as representative materials to prepare calcined clay-cement binary cementitious materials in order to study the effect of calcination treatment on the activation of clay minerals and the activity difference between layered and framed clays in this research.The influence of different calcined clay content(2%,4%,6%,8%,10%)on the fluidity,compressive strength,microstructure,phase change,and hydration heat of cement-based materials were analyzed.The calcined clay improves the fluidity of cement-based materials as compared with the uncalcined group.The addition of calcined montmorillonite(CMT)improves the development of mechanical strength,and the optimal compressive strength reaches 85 MPa at 28 days with 8%CMT.However,the activity of calcined clinoptilolite zeolite(CZL)is weak with few reaction sites,which slightly reduced the mechanical strength as compared to the blank sample.The addition of CMT changes the microscopic morphology of hydration products such as C-S-H and C-A-H,leading to the formation and transformation of ettringite in the early stage.It promotes the gradual polymerization of Si-O bonds into Si-O-Si bonds simultaneously,which accelerates the early hydration process.However,CZL acts mainly as a filling function in the cementitious system.In brief,CMT as an admixture can improve the mechanical properties of cement,but CZL has little effect.This work provides a guideline for the applications of calcined clay in cement,considering the influence of clay type on workability and mechanical strength.
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51964031 and 52164039)。
文摘The application of high-sulfur petroleum coke after desulfurization in aluminum electrolysis anodes is an important development trend. However, removing sulfur from high-sulfur petroleum coke is still a significant challenge.This study proposes alkali calcining and reflux washing to examine the impacts of temperature, particle size, the mass ratio of Na_(2)CO_(3) to NaOH, and total sodium addition on the desulfurization efficiency and mechanism. The results show that the desulfurization rate increases with increasing temperature, increasing total sodium content, and decreasing particle size. The addition of alkali can significantly reduce the opening-ring reaction temperature of thiophene and convert organic sulfur into inorganic sulfur(Na_(2)S). Three washing methods were compared, and reflux washing was selected to separate inorganic sulfur(Na_(2)S) from calcined petroleum coke. The sulfur content in petroleum coke decreased from 7.29% to 1.90%, with a desulfurization rate of 80.13% under optimal conditions. The petroleum coke was analyzed before and after desulfurization using X-Ray diffraction(XRD), Scanning Electron Microscopy(SEM), Infrared Spectroscopy(IR), Thermogravimetric Analysis and Differential Scanning Calorimetry(TG-DSC), Gaschromatography-mass Spectrometry(GC-MS). The results show that thiophene and benzothiophene in petroleum coke are decomposed and converted into octane and ethyl cyclohexane. These new observations are expected to provide further understanding and guidance for the utilization of highsulfur petroleum coke.
文摘The world’s total fossil fuel consumption has been significantly increasing with consequential increased environmental catastrophes. A hunt for an alternate energy source was stimulated. Biofuel is a plausible option in this pursuit due to its ideal qualities which included but are not limited to renewability and environmental friendliness. However, the pump price of biodiesel is still very high due mainly to the high cost of the production of the commodity which is influenced by the feedstock and the homogeneous nature of catalyst used. Heterogeneous catalyst was prepared by using Pila globosa sea snail shells prepared by calcination (CP8) and by acid activation (PTW1M). Hydnocapus weightiana seed oil (Non-edible feedstock) was extracted using the soxhlet extraction method and was used for biofuel production with a methanol oil ratio of 3:1. Agitation speed 800, 600 rmp, reaction temperatures of 70°C, 60°C, catalyst concentration (3.00, 2.00 wt%) and reaction time (70 and 60 min) was maintained for CP8 and PTW1M respectively. The rate of the reaction followed a reversible second-order reaction rate. Re-usability accessed. From TGA analysis, the best calcination temperature was 800°C. SEM results showed improved surface morphology after calcination, especially for CP8. FTIR analysis showed the elimination of volatiles and formation of CaO and CaO<sub>4</sub>Te after calcination. The reaction rate constant at different temperatures was 0.0287 at 30°C, 0.1200 at 50°C and 0.1142 at 70°C and activation energy of the ethyl ester was 49.49 KJ/mol. Using CP8. Most of the fuel properties met with ASTM 6751 standard. The result of the re-usability showed that the biodiesel yield declined as follows: 92, 86, 80, 73 and 69 % for CP8 and 85, 84, 81, 76, 65. For PTW1M. After the fifth regeneration cycle, both CP8 and PTW1M samples of Pila globosa sea snail shell catalyst proved effective in transesterification reaction of Hydnocapus weightiana seed oil using ethanol. It was observed that the calcined catalyst (CP8) showed a superior catalytic performance.
文摘Ordinary Portland Cement (OPC) is by mass the largest manufactured product on Earth, responsible for approximately 6% - 8% of global anthropogenic carbon dioxide emissions (CO<sub>2</sub>) and 35% of industrial CO<sub>2</sub> emissions. On average 0.8 to 0.9 ton of CO<sub>2</sub> is emitted to produce one ton of OPC. In this paper, partial substitution of clinker (30% - 35%) by the calcined clay-limestone mixture was investigated in order to produce an eco-cement (LC3). Analyzes by XRF, XRD and ATG/ATD have characterized different components, determined the calcination temperature and selected the right clay which can act as effective Supplementary Cementitious Material (SCM). Mechanical tests on mortar carried out over a period of 90 days. The WBCSD/WRI “Greenhouse Gas Protocol” methodology then allowed the calculation of CO<sub>2</sub> emissions into the atmosphere. Three types of clay are available in the Songololo Region. The kaolinite is the principal clay mineral and its content varies from 27% to 34%. The sum of kaolinite and amorphous phase which enable clay to react with cementitious material ranges from 57% to 60%. The SiO<sub>2</sub> content ranges from 33% to 76%, the Alumina content from 12% to 20% so that the ratio Al<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> is on the higher side (0.17 - 0.53). The calcination window is between 750°C and 850°C and the best clay which can act as SCM identified. The clinker’s substitution reduced CO<sub>2</sub> emissions from 0.824 ton of CO<sub>2</sub> for one ton of OPC to 0.640 ton of CO<sub>2</sub> for one ton of LC3, means 22% less emissions. The compressive strengths developed by LC3 vary from 8.91 to 57.6 MPa (Day 1 to Day 90), exceed those of references 32.5 cement and are close to 42.5 cement. In view of the results, LC3 cement can be considered for industrial trials.
文摘This paper presents a study of the potential use of iron mining tailings as artificial pozzolan (metakaolin) after their submission to thermal treatment via calcination in a flash furnace. The research consists of the characterization of the tailings before and after calcination, chemical, mineralogical, thermogravimetric, and mechanical strength analyses were conducted. The results were compared with those for commonly used pozzolans, metakaolin, and similarities were identified. The study of the morphology of the particles before and after calcination was conducted through analyses of images obtained by scanning electronic microscope. The pozzolanic activity of the fine mining tailings calcined with flash technology was evaluated in uniaxial compression trials, which showed excellent results.
文摘As the coal combustion behaviors are rather complex in the cement industry, the traditional assessment method cannot be directly applied to evaluate the quality of coal. Based on the thermal analysis tests of more than 80 kinds of anthracite and bituminous coal, three evaluation parameters, namely, burning intensity (I), average capacity of heat release (Q), and general burning index (S) are presented, combining with the consideration of application and calciner types in the cement industry. Taking these three parameters into consideration together is necessary. Experimental results show that the coal with higher S, lower I and higher Q can be rated as the best for the calciner in the cement industry. The quantitative indexes are given to evaluate the bituminous coal and anthracite in this paper. This new assessment method has implications for the design of calciner in the cement industry.
文摘A significant amount of aluminum dross is available as a waste in foundry industries in Bangladesh. In this study, alumina was ex- tracted from aluminum dross collected from two foundry industries situated in Dhamrai and Manikgang, near the capital city, Dhaka. Alu- minum dross samples were found to approximately contain 75wt% A1203 and 12wt% SIO2. An acid dissolution process was used to recover the alumina value from the dross. The effects of various parameters, e.g., temperature, acid concentration, and leaching time, on the extrac- tion of alumina were studied to optimize the dissolution process. First, AI(OH)3 was produced in the form of a gel. Calcination of the AI(OH)3 gel at 1000℃, 1200℃, and 1400℃ for 2 h produced O-AlcOa, (t~+O)-A1203, and u-alumina powder, respectively. Thermal charac- terization of the AI(OH)3 gel was performed by thermogravimetric/differential thermal analysis (TG/DTA) and differential scanning calo- rimetry (DSC). The phases and crystallite size of the alumina were determined by X-ray diffraction analysis. The dimensions of the alumina were found to be on the nano level. The chemical compositions of the aluminum dross and alumina were determined by X-ray fluorescence (XRF) spectroscopy. The microstructure and morphology of the alumina were studied with scanning electron microscopy. The purity of the alumina extracted in this study was found to be 99.0%. Thus, it is expected that the obtained alumina powders can be potentially utilized as biomaterials.
基金financially supported by NSAF(No.U1530155)Ministry of Science and Technology(MOST)of China,US–China Collaboration on Cutting-edge Technology Development of Electric Vehicle,the Nation Key Basic Research Program of China(No.2015CB251100)Beijing Key Laboratory of Environmental Science and Engineering(No.20131039031)
文摘A spherical-like Ni_(0.6)Co_(0.2)Mn_(0.2)(OH)_2 precursor was tuned homogeneously to synthesize LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 as a cathode material for lithium-ion batteries.The effects of calcination temperature on the crystal structure,morphology,and the electrochemical performance of the as-prepared LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 were investigated in detail.The as-prepared material was characterized by X-ray diffraction,scanning electron microscopy,laser particle size analysis,charge–discharge tests,and cyclic voltammetry measurements.The results show that the spherical-like LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 material obtained by calcination at 900°C displayed the most significant layered structure among samples calcined at various temperatures,with a particle size of approximately 10 μm.It delivered an initial discharge capacity of 189.2 m Ah×g^(-1) at 0.2C with a capacity retention of 94.0% after 100 cycles between 2.7 and 4.3 V.The as-prepared cathode material also exhibited good rate performance,with a discharge capacity of 119.6 m Ah×g^(-1) at 5C.Furthermore,within the cut-off voltage ranges from 2.7 to 4.3,4.4,and 4.5 V,the initial discharge capacities of the calcined samples were 170.7,180.9,and 192.8 m Ah×g^(-1),respectively,at a rate of 1C.The corresponding retentions were 86.8%,80.3%,and 74.4% after 200 cycles,respectively.
基金financially supported by Independent Research Subject from Ministry of Science and Technology of China(No.2008BWZ005)
文摘Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried out over coral reef-like Ni/Al2O3 catalysts in a continuous flow type fixed-bed reactor.The structure and properties of the fresh and used catalysts were studied by SEM,N2 adsorption-desorption,XRD,H2-TPR,O2-TPO,TG and ICP-AES techniques.The results showed that the coral reef-like Ni/Al2O3 catalysts exhibited better activity than the conventional Ni/Al2O3-H2O catalysts.The activities of coral reef-like catalysts were in the order of Ni/Al2O3-673Ni/Al2O3-573Ni/Al2O3- 473Ni/Al2O3-773.Ni/Al2O3-673-EG catalyst showed not only good activity and improved stability but also superior resistance to carbon deposition,sintering,and Ni loss.Under the reaction conditions of CO/H2(molar ratio)=1:3,593 K,atmospheric pressure and a GHSV of 2500 h-1,CH4 selectivity was 84.7%,and the CO conversion reached 98.2%.
基金supported by the Chinese Nonferrous Guilin Research Institute of Geology for Mineral Resource (No.ky20101372000001)
文摘Muscovite mineral was roasted in different conditions.Rubidium leaching rate was a standard to examine the impact of various factors on calcination effect,including the agent types,roasting time,mass ratio,and roasting temperature.The results indicate that the best agent is the combination of sodium chloride and calcium chloride,and its mass ratio of muscovite/NaCl/CaCl2is1.00:0.25:0.25.Calcined at 850℃ for 30 min,the rubidium leaching rate is up to 90.12%.The reaction of muscovite ore with the chlorinating agent CaCl2was studied by TG/DSC,and the surface morphology before and after leaching was characterized by SEM.Rubidium chloride products can be obtained using t-BAMBP extraction,hydrochloric acid re-extraction,and purification.
基金financially supported by the Open Foundation of Engineering Center of Avionics Electrical and Information Network of Guizhou Province Colleges and Universities (No.HKDZ201404)
文摘Trace Na sources, extraction dynamics of trace Na, and influences of calcination temperature on quartz lattice, fluid inclusions, and muscovite were studied in detail herein for trace Na extraction from the quartz ore with water leaching at 90℃. Experimental results suggested that the trace Na sources included quartz lattice, fluid inclusions, and muscovite. The extraction rate of the trace Na in quartz ores can reach 31.0wt% after calcination at 900℃ for 5 h and water leaching at 90℃ for 24 h. The extraction process consisting of the dissolution of unfree Na and diffusion of free Na was dominated by calcination temperature. Calcination at 900℃ for 5 h was effective for extraction of the trace Na in fluid inclusions and muscovite. The extraction of the trace Na was mainly affected by the decrepitation of fluid inclusions when the calcination temperature ranged from 400 to 600℃ and by the damage of muscovite when the calcination temperature ranged from 600 to 900℃. Based on the extraction rates at different calcination temperatures, approximately 20.1wt% of the trace Na occurred in fluid inclusions, approximately 10.9wt% existed in muscovite, and 69.0wt% mainly occurred in quartz lattice.
文摘Effects of different heat treatment temperatures on properties of Chinese calcined flint clay based plastic refractories were investigated using Chinese calcined flint clay as starting material, aluminum sulfate and fireclay as binding system. The results showed that with temperature rising, Chinese calcined flint clay based plastic refractories shrinked firstly and then expanded. The modulus of rupture (MOR) and the cold crushing strength (CCS) inereased firstly and then decreased from 110 ℃ to 600 ℃ , then increased obviously. Thermal expansion coefficient increased from 110 ℃ to 760 ℃, decreased from 760 ℃ to 1 300 ℃ , and increased from 1 300 ℃ to1500 ℃.
基金supported by the Natural Science Foundation of Fujian Province (No. T08J0129)the Science and Technology Developing Foundation of Fuzhou University (No. 2008-XQ-001)2007-year New Century Talents Supporting Program of Fujian Province (No.XSJRC2007-17)
文摘We aim in this research at synthesizing high-purity aluminium titanate with sludge from the aluminium profile factory by shock cooling method, and mainly discuss the effect of calcining reaction temperature and holding time on crystalline, microstructure and content of aluminum titanate materials to determine the preferred calcining temperature and holding time. XRD and SEM methods were utilized to characterize the crystalline and microstructure of each specimen, Rietveld Quantification software was used for the determination of different crystalline contents of specimens, and Philips plus software was applied to determine the cell parameters of aluminium titanate in different specimens. According to the experimental results, preferred calcining temperature is determined as 1400℃ and preferred holding time is 2 h, at which the grains of aluminum titanate grow completely and the purity of aluminum titanate is 97.2wt%.
基金Funded by the National Key Research and Development Program of Science and Technology of China(No.2018YFB1501002).
文摘Mullite and corundum co-bonded SiC-based composite ceramics(SiC-mullite-Al2O3)were prepared by using SiC,calcined bauxite and kaolin via pressureless carbon-buried sintering.The low-cost SiC-based composite ceramics designed in this study are expected to be used as thermal storage materials in solar thermal power generation based on the high density and excellent thermal shock resistance.The influences of calcined bauxite addition and sintering temperature on the microstructures,phase compositions,and physical properties of the samples were investigated.Results demonstrated that the introduction of calcined bauxite containing two bonding phases greatly reduced the lowest sintering temperature to 1400℃.The SiC-mullite Al2O3 composite with 40 wt%calcined bauxite sintered at 1500℃exhibited optimum performance.The density and bending strength were 2.27 g·cm^-3 and 77.05 MPa.The bending strength increased by 24.58%and no cracks were observed after 30 thermal shock cycles,while general clay would reduce the thermal shock resistance of SiC.The SiC-mullite-Al2O3 composites with satisfied performance are expected to be used as thermal storage materials in solar thermal power generation systems.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.U1812402,51664005,and 51774102)Talents of Guizhou Science and Technology Cooperation Platform(Talent Team Giant[2015]4005,Platform Talent[2017]5788,[2017]5626,and KY(2015)334).
文摘To enable the utilization of low-grade and high-sulfur bauxite, the suspension calcination was used to remove the sulfur and the activate silica minerals, and the calcinated bauxite was subjected to a desilication process in Na OH solution under atmospheric pressure. The desulfurization and desilication properties and mineralogical evolution were studied by X-ray diffraction, thermogravimetry–differential thermal analysis, scanning electron microscopy, and FactSage methods. The results demonstrate that the suspension calcination method is efficient for sulfur removal: 84.21% of S was removed after calcination at 1000°C for 2 min. During the calcination process, diaspore and pyrite were transferred to α-Al2O3, magnetite, and hematite. The phase transformation of pyrite follows the order FeS2 → Fe3O4 → Fe2O3, and the iron oxides and silica were converted into iron silicate. In the alkali-soluble desilication process, the optimum condition was an alkali solution concentration of 110 g/L, a reaction time of 20 min, and a reaction temperature of 95°C. The corresponding desilication ratio and alumina loss ratio were 44.9% and 2.4%, respectively, and the alumina-to-silica mass ratio of the concentrate was 7.9. The Al2O3·2SiO2, SiO2, and Al2O3 formed during the calcination process could react with Na OH solution, and their activity decreased in the order of Al2O3·2 SiO2, SiO2, and Al2O3.
文摘A series of x (Fe,Ni)/Al2O3 catalysts (x = 2-12 wt%) were prepared using incipient wetness method and studied for the conversion of synthesis gas to light olefins.6 wt%(Fe,Ni)/Al2O3 catalyst was found to be the optimal catalyst for the production of C2-C4 olefins.The effects of calcination behaviors and operational conditions on the catalytic performance of the optimal catalyst were investigated.The best operational conditions were molar feed ratio H2/CO = 2/1,T = 260 ℃,gas hourly space velocity (GHSV) = 2600 h^-1 and the pressure of 3 bar.Character-izations of both precursors and catalysts were carried out using X-ray diffraction (XRD),temperature-programmed reduction (TPR),scanning electron microscopy (SEM),N2-adsorption-desorption measurement,thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC).
文摘In this study,selective dealumination of Beta zeolites was performed through partially removing the templating agent in Beta zeolites by calcination and then removing the aluminum on the external surface of Beta zeolites with acid treatment.Hydrocracking catalysts were prepared by loading WO_(3)onto these dealuminated Beta zeolites.It was shown that the surface SiO_(2)/Al_(2)O_(3)of selectively dealuminated Beta zeolites was higher than that of conventionally dealuminated samples for the same bulk SiO_(2)/Al_(2)O_(3),and the hydrogenation activity of the catalyst of the selectively dealuminated Beta zeolites was lower than that of conventionally dealuminated Beta zeolites.The experimental results for tetralin hydrocracking to BTX showed that the catalysts based on the selectively dealuminated Beta zeolites had higher BTX selectivity and lower coke formation rate than that the catalysts based on the conventionally dealuminated Beta zeolites.