The appropriate content and distribution of sinter moisture play an important role in the granulation of iron ores. In this study, the effects of porosity, size distribution, and particle shape on the water absorption...The appropriate content and distribution of sinter moisture play an important role in the granulation of iron ores. In this study, the effects of porosity, size distribution, and particle shape on the water absorption rate （WAR） of four types of iron ores were analyzed by using the immersion method and capillary water absorption method. In addition, the mechanism underlying the water absorption process in iron ores was unraveled. It is found that the WARs of iron ores decrease quickly with the increase in water absorption time at the initial stages of water absorption. With further increase in absorption time, the WARs decrease gradually, until near 0. Iron ores with higher porosity, smaller particle size, and plate-like structure have the higher WARs. Compared with pores in the single-particle iron ore, voids among particles in the multi-particle iron oxide play an important role at the initial stages of water absorption. The water absorption mechanism of all single-particle and multi-particle iron ores analyzed in this study includes four steps, wherein the first three steps play a significant role in the sintering pro-cess.展开更多
The present work was done in order to develop and find out suitable conversion methods for coconut husk wastes into value-added products. It is well-known that coconuts husk waste is hydrophobic therefore ethanol with...The present work was done in order to develop and find out suitable conversion methods for coconut husk wastes into value-added products. It is well-known that coconuts husk waste is hydrophobic therefore ethanol with different doses was used as a surfactant to enhance the removal efficiency. Treated samples at different adsorbent amounts, sintering temperatures & sintering time, stirring time, pH, and solution temperatures for color removal of Methylene Blue (MB) & Rhodamine B (RhB) and ammonium concentration were evaluated by using UV-Visible Spectroscopy. At 300°C, results showed complete removal for MB and more than 75% for RhB, whereas removal of ammonium ion reached around 52% when sintering product from husk waste was used. Further investigation was carried out for ammonium ion to understand the desorption kinetic behaviors and isotherm models. Kinetics indicated that desorption of ammonium ion followed pseudo-first order equation. Adsorption thermodynamic parameters such as ΔG, ΔH, and ΔS followed Van’t Hoff plot for adsorption and found to be negative which indicated that the adsorption process for ammonium onto coconut husk was physical, spontaneous and exothermic.展开更多
The cold sintering process(CSP)is a green and innovative method of material densification at low temperatures(<350°C).The traditional CSP entails the addition of liquid phases as a solvent to achieve material ...The cold sintering process(CSP)is a green and innovative method of material densification at low temperatures(<350°C).The traditional CSP entails the addition of liquid phases as a solvent to achieve material densification through the dissolution-precipitation mechanism.However,it is difficult to realize for materials with low solubility.To address this challenge,a universal cold sintering method without the addition of liquid phases has been proposed in this work.The addition of a special polyester-polymer assisted the densification of insoluble ceramics,and hydroxyapatite(HA)and Al_(2)O_(3)were successfully sintered below 100°C,achieving 95-100%densities in a short time(5-20 min).This achievement can be attributed to the low glass transition temperature and the abundance of active sites(C=O)of the polyester-polymer.The denser ceramics exhibited enhanced mechanical properties,with the compression strength of polymer-assisted CSP HA increasing by 147.3%compared to the nanoparticles.Additionally,serving as an advanced bone substitute material,HA underwent quantitative analysis using the CCK-8 method and assessed the impact of polymer presence on cell proliferation and cytotoxicity.Meanwhile,a tight bonding between the polymer and ceramic materials was achieved during CSP,providing a generalized method for designing multifunctional ceramic-polymer.展开更多
Iron and steel industry is one of the main sources of air pollution emissions in China.The sintering process is an important link in the blast furnace ironmaking process,but it is also accompanied by a large number of...Iron and steel industry is one of the main sources of air pollution emissions in China.The sintering process is an important link in the blast furnace ironmaking process,but it is also accompanied by a large number of pollutants.Under the background of ultra-low emissions,iron and steel enterprises urgently need to upgrade their existing processes to address the existing process in practical application problems.In this study,a steel group in Gansu Province was taken as an example.By comparing and analyzing the pollutant emission characteristics before and after the ultra-low emission retrofit,the collaborative control effect of the combined process on SO_(2),NO_(x),particulate matter,and dioxins after the new retrofit was systematically evaluated.The results show that after the retrofit,the concentrations of particulate matter,SO_(2) and NO_(x) have dropped to near-zero levels,and the dioxin removal efficiency has reached 98.87%,with all indicators being better than the national ultra-low emission standards.The study confirms that the optimal combination of multi-pollutant collaborative treatment technologies is the key to achieving efficient emission reduction,among which selective catalytic reduction technology has a particularly significant synergistic removal effect on NO_(x) and dioxins.This study provides an important technical reference and practical basis for the ultra-low emission retrofit of the steel industry,and has important guiding significance for promoting the green retrofit of the industry.Its ultra-low emission retrofit is of great significance for achieving green and low-carbon development.展开更多
The use of high entropy alloy as a binder for tungsten heavy alloys offers potential advantages.The 95W-5CoCrFeMnNi alloys(95W-HEAs)were prepared via powder metallurgy at sintering temperatures of 1400−1550℃.The micr...The use of high entropy alloy as a binder for tungsten heavy alloys offers potential advantages.The 95W-5CoCrFeMnNi alloys(95W-HEAs)were prepared via powder metallurgy at sintering temperatures of 1400−1550℃.The microstructure analysis revealed that the tungsten phase in 95W-HEAs exhibited a nearly spherical morphology in the HEA binder matrix and the formation of a Cr−Mn oxide mixed phase was observed.The sintering temperature exerted a significant influence on the relative density,grain size,W−W contiguity,and mechanical properties of the alloys.The optimal performance was achieved when sintering at 1450℃,yielding a relative density of 96.61%,a W−W contiguity of 0.528,an average grain size of 18.97μm,a compressive strength of 2234.82 MPa,and a hardness of HV 400.6.The activation energy for the diffusion of tungsten in the liquid phase formed by HEA binder was calculated to be 354.514 kJ/mol,highlighting its role in controlling grain growth.展开更多
Powder paving is an intermediate process of selective laser sintering(SLS).The dimensional accuracy and mechanical properties of sintered components are directly affected by the quality of the powder paving process,wh...Powder paving is an intermediate process of selective laser sintering(SLS).The dimensional accuracy and mechanical properties of sintered components are directly affected by the quality of the powder paving process,which is closely related to the flow characteristics of the powder and the process parameters of powder paving.This study investigated the simulation and optimization of the nylon powder paving in SLS by combining a discrete-element-method numerical simulation with a process test.A dynamic model was established to describe the flow and paving process of nylon powder at a preheating temperature considering mesoscopic van der Waals and electrostatic forces.The effects of the physical parameters and ambient temperature on the flow characteristics of nylon powder were analyzed,and the intrinsic relationship between the physical parameters of nylon powder,the process parameters of powder paving,and the quality of the powder paving were explored.A multi-objective regression model of the quality of powder paving was established using the response surface methodology,and a genetic algorithm was adopted to optimize the quality of the powder paving.A scientific and intelligent database of the nylon powder paving process in SLS was constructed by matching the process parameters of powder paving and physical parameters of the nylon powder,and the level of the SLS process was improved.展开更多
This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C s...This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C significantly improved the mechanical properties, including a notable 18.2% increase in hardness(HV 332). Fretting wear tests against 316L stainless steel(SS316L) balls demonstrated a 20wt%–22wt% reduction in wear volume in the Ti6Al4V/Ti C composites compared with the monolithic alloy. Microstructural analysis revealed that Ti C reinforcement controlled the grain orientation and reduced the β-phase content, which contributed to enhanced mechanical properties. The monolithic alloy exhibited a Widmanstätten lamellar microstructure, while increasing the Ti C content modified the wear mechanisms from ploughing and adhesion(0–0.5wt%) to pitting and abrasion(1wt%–2.5wt%). At higher reinforcement levels, the formation of a robust oxide layer through tribo-oxide treatment effectively reduced the wear volume by minimizing the abrasive effects and plastic deformation. This study highlights the potential of SPS-mediated Ti C reinforcement as a transformative approach for improving the performance of Ti6Al4V alloys, paving the way for advanced medical applications.展开更多
Coke oven gas(COG)and natural gas(NG),both high-calorific by-products derived from the steel industry,have gained prominence as alternative fuels in the sintering process,thereby supporting dual objectives of emission...Coke oven gas(COG)and natural gas(NG),both high-calorific by-products derived from the steel industry,have gained prominence as alternative fuels in the sintering process,thereby supporting dual objectives of emission reduction and carbon neutrality.While existing research on hydrogen-rich gas injection has predominantly concentrated on conventional thin-bed sintering,investigations into its application within thick-bed sintering remain comparatively scarce.Thick-bed sintering,recognized for enhancing energy efficiency and increasing sinter output,encounters challenges such as uneven heat distribution and diminished permeability,which can negatively impact process efficiency and product quality.To address these issues,sinter pot experiments were conducted to assess the effects of NG and COG injection on thick-bed sintering performance.Findings reveal that NG injection in thick beds mirrors the behavior observed in conventional thin-bed sintering,effectively optimizing the process and achieving a carbon reduction potential exceeding 10%.In contrast,COG injection in thick-bed conditions demonstrates notable differences,substantially lowering the solid fuel consumption rate but detrimentally affecting sinter strength and overall production.However,by optimizing the timing of COG injection,it is feasible to improve sinter yield while concurrently reducing solid fuel usage.These outcomes provide valuable insights for the advancement of gas injection technologies in thick-bed sintering,thereby contributing to energy conservation and emission mitigation efforts within the sintering industry.展开更多
Sintering is a critical process in steel production that facilitates the efficient utilization of iron ore resources.However,compared to advanced sintering technologies,China’s sintering methods still exhibit high en...Sintering is a critical process in steel production that facilitates the efficient utilization of iron ore resources.However,compared to advanced sintering technologies,China’s sintering methods still exhibit high energy consumption,with typical solid fuel consumption for sintering of about 55 kg/t.In response,a pellet sintering process has been developed and its behavior has been investigated at sintering bed heights of 750 and 1500 mm.Additionally,a technical and economic comparison with traditional sintering methods has been conducted.The results indicate that at a bed height of 750 mm,the pellet sintering method can significantly reduce solid fuel consumption by approximately 30.82%,dropping from 70.75 to 48.95 kg/t.Additionally,the coke rate decreased from 4.55%to 3.20%,and harmful emissions in the flue gas were also reduced.As the bed height increases to 1500 mm,sintering performance improves even further.The coke rate is reduced to 3.00%,and solid fuel consumption decreases to 41.27 kg/t,approaching the world’s advanced level(≤40 kg/t).Technical and economic analysis also indicates that adopting the pellet sintering process can lower sintering costs by about 2.18 dollars/t.展开更多
A pre-reduction sintering process with flue gas recirculation(PSP_(fsg)-FGR)was developed to mitigate alkalis harm to the blast furnace and reduce the flue gas emission in the whole ironmaking process.The results indi...A pre-reduction sintering process with flue gas recirculation(PSP_(fsg)-FGR)was developed to mitigate alkalis harm to the blast furnace and reduce the flue gas emission in the whole ironmaking process.The results indicated that the pre-reduction sintering process(PSP)can effectively remove 58.02%of K and 30.68%of Na from raw mixtures and improve yield and tumbler index to 74.40%and 68.69%,respectively.Moreover,PSP was conducive to reducing NO_(x) and SO_(2)emissions and simultaneously increasing CO content in flue gas.Circulating CO-containing flue gas to sintering bed effectively recycled CO and further improved K and Na removal ratio to 74.11%and 32.92%,respectively.Microstructural analysis revealed that the pre-reduced sinter mainly consisted of magnetite,wustite and a small quantity of metallic iron,and very few silicate glass phase was also formed.This process can simultaneously realize alkali metal elements removal as well as flue gas emission reduction from the integrated ironmaking process.展开更多
By means of the synthetic approach of non－polar or weak polar oil－sorbed polymers，the gel sorption resin（GSR） and the multiporous sorption resin（MSR） were prepared．The structure of the resins，sorption power...By means of the synthetic approach of non－polar or weak polar oil－sorbed polymers，the gel sorption resin（GSR） and the multiporous sorption resin（MSR） were prepared．The structure of the resins，sorption power，sorption speed，desorption，and sorption of organic compounds from sewage，exhaust gas and soil were discussed．Moreover，the resins were used to decrease LOD and BOD5 values of water waste from sewage factory．Theyare a klndof potential materials for environmental control．展开更多
During the sintering process of iron ore,a large amount of nitrogen oxides is generated,for which there is currently no efficient and economical treatment process.Therefore,it is necessary to implement process control...During the sintering process of iron ore,a large amount of nitrogen oxides is generated,for which there is currently no efficient and economical treatment process.Therefore,it is necessary to implement process control in sintering production to keep the mass concentration of NO_(x)in sintering flue gas at a low level.Through industrial trials at sintering sites,methods such as correlation analysis,path analysis,and multiple linear regression were applied to analyze the influence of various factors on NO emissions during the sintering process.The results indicate that negative correlations exist between nitrogen monoxide(NO)emissions and negative pressure,permeability index,O_(2) concentration,CO concentration,and flue gas temperature.Conversely,positive correlations exist between NO emissions and dust concentration,water vapor volume fraction,and sintering bed speed.Among these factors,O_(2) concentration and dust concentration are identified as the most significant influencing factors on NO emissions.By analyzing the masses and modes of influence of different factors,the mechanisms of action of each factor were obtained.Specifically,O_(2) concentration,dust concentration,permeability index,CO concentration,and flue gas temperature play a direct dominant role in NO emissions during the sintering process,while water vapor volume fraction,sintering trolley speed,and negative pressure have an indirect effect.A predictive model for NO mass concentration in flue gas was established with an accuracy rate of 91.6%,showing consistent overall trends with actual values.Finally,denitrification strategies for sintering industrial production were proposed,along with prospects for preliminary denitrification of sintering flue gas using fluidized bed conditions in the duct.展开更多
Volatile organic compounds(VOCs)present significant risks to both human health and the environment.As a result,there has been increasing research on their formation processes,emission patterns,and emission reduction t...Volatile organic compounds(VOCs)present significant risks to both human health and the environment.As a result,there has been increasing research on their formation processes,emission patterns,and emission reduction technologies.Sintered ore,a key raw material in ironmaking,requires substantial amounts of fossil fuels such as coal and coke in its production,leading to significant VOC emissions.However,research on VOC emission patterns during the sintering process remains limited.Thus,the influence of factors such as moisture content in the sintering mixture,fuel type,fuel ratio,and coal-to-coke ratio on VOC emissions was investigated through sintering cup experiments.Additionally,the reaction pathways of hydrocarbons within the sintering bed were analyzed using temperature distribution and thermodynamic calculations.In the sintering process using coke powder,the emissions of total volatile organic compounds and non-methane hydrocarbons per ton of sintered ore are 18.78 and 11.14 g,respectively,whereas emissions from coal are substantially higher at 378.27 and 32.55 g.VOC emissions exhibit a linear correlation with the total volatile matter input during sintering,with most VOCs originating from volatile matter.The improved heat transfer conditions reduce the preheating zone thickness,allowing more VOCs to remain in the high-temperature region.展开更多
Steel rolling sludge,an oil-containing waste generated during steel production,was difficult to manage.Prolonged storage poses significant environmental and health hazards.Most steel enterprises in China use steel rol...Steel rolling sludge,an oil-containing waste generated during steel production,was difficult to manage.Prolonged storage poses significant environmental and health hazards.Most steel enterprises in China use steel rolling sludge directly as a raw material for sintering.However,its adhesive nature caused poor mixing with other materials,affecting the quality of the sinter.Herein,the incorporation of steel rolling sludge incineration slag into the sintering process was investigated for experimental purposes.The results indicated that adding 1%incinerated steel rolling sludge to the sintering raw material was feasible.At this proportion,both the yield and the tumbler index of the sinter have improved,primarily due to the oxidation reaction of Fe_(3)O_(4)present in the steel rolling sludge incineration slag during the sintering process,which significantly increases the sensible heat of the sinter and enhances the sintering mineralization reaction.Notably,the addition of steel rolling sludge incineration slag reduced dioxin concentrations in the sintering flue gas.Although CO,NO_(x),and SO_(2)emission concentrations slightly increased,the existing flue gas treatment system effectively controlled their emissions.展开更多
Yttrium hydride(YH_(x))is a highly promising neutron moderator material for nuclear reactors,known for its exceptional thermal stability and high hydrogen content.This study investigated the sintering mechanism and mi...Yttrium hydride(YH_(x))is a highly promising neutron moderator material for nuclear reactors,known for its exceptional thermal stability and high hydrogen content.This study investigated the sintering mechanism and microstructural evolution of YH_(x)monoliths processed by spark plasma sintering(SPS),with the effects of temperature,duration,and pressure.The results indicate that the sintering process can be divided into five stages:formation of sintering necks,rapid densification,anti-densification,recrystallization,and grain growth.The anti-densification behavior is attributed to hydrogen desorption,phase transformation-induced volumetric contraction,and vacancy coalescence from hydrogen migration,leaving residual pores and lattice defects.Furthermore,increasing the sintering temperature and duration promotes recrystallization and grain growth,whereas elevated pressure effectively suppresses grain boundary migration.This research establishes fundamental processing-structure correlations critical for optimizing YHx moderators in nuclear applications.展开更多
Sinter is the core raw material for blast furnaces.Flue pressure,which is an important state parameter,affects sinter quality.In this paper,flue pressure prediction and optimization were studied based on the shapley a...Sinter is the core raw material for blast furnaces.Flue pressure,which is an important state parameter,affects sinter quality.In this paper,flue pressure prediction and optimization were studied based on the shapley additive explanation(SHAP)to predict the flue pressure and take targeted adjustment measures.First,the sintering process data were collected and processed.A flue pressure prediction model was then constructed after comparing different feature selection methods and model algorithms using SHAP+extremely random-ized trees(ET).The prediction accuracy of the model within the error range of±0.25 kPa was 92.63%.SHAP analysis was employed to improve the interpretability of the prediction model.The effects of various sintering operation parameters on flue pressure,the relation-ship between the numerical range of key operation parameters and flue pressure,the effect of operation parameter combinations on flue pressure,and the prediction process of the flue pressure prediction model on a single sample were analyzed.A flue pressure optimization module was also constructed and analyzed when the prediction satisfied the judgment conditions.The operating parameter combination was then pushed.The flue pressure was increased by 5.87%during the verification process,achieving a good optimization effect.展开更多
Poor permeability and low sintering productivity restrict the development of high-bed sintering.An efficient method of the double-layer sintering process(DLSP)was proposed to achieve high-bed sintering and solve the a...Poor permeability and low sintering productivity restrict the development of high-bed sintering.An efficient method of the double-layer sintering process(DLSP)was proposed to achieve high-bed sintering and solve the aforementioned problems.Theoretical calculation and sintering pot experiments were implemented to investigate the double-layer sintering process.Traditional sintering process and DLSP were compared in terms of sintering indices,metallurgical properties and morphology characterization.Under the condition of traditional sintering process,DLSP successfully realized fast velocity and highly productive sintering of 1000-mm high bed.After the sintering bed is charged and ignited twice,the air permeability of the bed has been greatly improved.Sintering time is shortened significantly by simultaneous sintering of the upper and lower feed layers.Under the condition of bed height proportion of 350/650 mm and pre-sintering time of 20 min,the yield,tumbler strength,productivity and solid fuel consumption are 69.96%,65.87%,1.71 t(m^(2)h)^(-1)and 56.71 kg/t,respectively.Magnetite,hematite,calcium ferrite and complex calcium ferrite are the main phases of DLSP products.The metallurgical properties of DSLP products meet the requirement of ironmaking.It indicates that DLSP is an effective method to solve the disadvantages of bad permeability and low sintering productivity in high-bed sintering.展开更多
The challenge of low temperature and rapid diffusion bonding of a Ni-based superalloy was hereby addressed by using a Ni nano-coating and a spark plasma sintering(SPS).It successfully produced a Nibased superalloy joi...The challenge of low temperature and rapid diffusion bonding of a Ni-based superalloy was hereby addressed by using a Ni nano-coating and a spark plasma sintering(SPS).It successfully produced a Nibased superalloy joint with 337 MPa shear strength at 500℃ for 30 min,which is approximately 400℃ lower than the traditional hot pressure diffusion bonding(HPDB)temperature.The microstructure and mechanical properties of the joints were systematically investigated.It is revealed that the pulsed current and ultra-fine grains(19 nm)in the Ni nano-coating could significantly facilitate voids closure.The voids closure mechanisms involved(i)pulsed current strengthened plastic deformation,(ii)pulsed current strengthened surface source diffusion,(iii)pulsed current strengthened bonding interface diffusion,(iv)grain growth dividing the initial large voids into nano-voids,and(v)massive grain boundaries(GBs),lattice defects,and local high-temperature strengthened GBs diffusion.Furthermore,the GBs migration across the interface was investigated,and the results revealed that the GBs migration and fine grains(350 nm)near the bonding interface together increased the joint strength.展开更多
As the bed depth increases,sintering yield increases,but the productivity decreases.To reveal the reasons for the decrease in productivity and explore targeted solutions,the bed resistance of mixtures,wet zone,and com...As the bed depth increases,sintering yield increases,but the productivity decreases.To reveal the reasons for the decrease in productivity and explore targeted solutions,the bed resistance of mixtures,wet zone,and combustion zone was analyzed in the laboratory.The results showed that the decreased porosity of mixture resulted in the increased bed resistance by 160.56%when the bed depth increased from 600 to 1000 mm.After improving porosity of 1%by adding loosening bars with optimized size and distribution,the bed resistance decreased,and the productivity increased by 5%.The increase in bed depth increased the thickness of the wet zone from 120 to 680 mm and the resistance from 1.56 to 8.83 kPa.By using a three-stage intensive mixer and pre-adding water for granulation,the moisture of mixture was reduced by 0.6%,and the sintering productivity increased by 4%.Besides,the high bed resistance is mainly caused by the increase in the thickness of the combustion zone from 31.9 to 132.7 mm,and the bed resistance increased from 0.70 to 5.62 kPa.The bed resistance of the combustion zone at 900 mm was increased by 90.51%compared to 700 mm.After optimization of the distribution of coke breeze,the thickness of combustion zone at the lower layer decreased from 132.7 to 106.84 mm and permeability improved significantly.展开更多
A key component of future lunar missions is the concept of in-situ resource utilization(ISRU),which involves the use of local resources to support human missions and reduce dependence on Earth-based supplies.This pape...A key component of future lunar missions is the concept of in-situ resource utilization(ISRU),which involves the use of local resources to support human missions and reduce dependence on Earth-based supplies.This paper investigates the thermal processing capability of lunar regolith without the addition of binders,with a focus on large-scale applications for the construction of lunar habitats and infrastructure.The study used a simulant of lunar regolith found on the Schr?dinger Basin in the South Pole region.This regolith simulant consists of20 wt%basalt and 80 wt%anorthosite.Experiments were conducted using a high power CO_(2)laser to sinter and melt the regolith in a 80 mm diameter laser spot to evaluate the effectiveness of direct large area thermal processing.Results indicated that sintering begins at approximately 1180℃and reaches full melt at temperatures above 1360℃.Sintering experiments with this material revealed the formation of dense samples up to 11 mm thick,while melting experiments successfully produced larger samples by overlapping molten layers and additive manufacturing up to 50 mm thick.The energy efficiency of the sintering and melting processes was compared.The melting process was about 10 times more energy efficient than sintering in terms of material consolidation,demonstrating the promising potential of laser melting technologies of anorthosite-rich regolith for the production of structural elements.展开更多
基金financially supported by the National Natural Science Foundation of China(No.U1260202)the Fundamental Research Funds for the Central Universities(No.FRF-MP-12-003B)
文摘The appropriate content and distribution of sinter moisture play an important role in the granulation of iron ores. In this study, the effects of porosity, size distribution, and particle shape on the water absorption rate （WAR） of four types of iron ores were analyzed by using the immersion method and capillary water absorption method. In addition, the mechanism underlying the water absorption process in iron ores was unraveled. It is found that the WARs of iron ores decrease quickly with the increase in water absorption time at the initial stages of water absorption. With further increase in absorption time, the WARs decrease gradually, until near 0. Iron ores with higher porosity, smaller particle size, and plate-like structure have the higher WARs. Compared with pores in the single-particle iron ore, voids among particles in the multi-particle iron oxide play an important role at the initial stages of water absorption. The water absorption mechanism of all single-particle and multi-particle iron ores analyzed in this study includes four steps, wherein the first three steps play a significant role in the sintering pro-cess.
文摘The present work was done in order to develop and find out suitable conversion methods for coconut husk wastes into value-added products. It is well-known that coconuts husk waste is hydrophobic therefore ethanol with different doses was used as a surfactant to enhance the removal efficiency. Treated samples at different adsorbent amounts, sintering temperatures & sintering time, stirring time, pH, and solution temperatures for color removal of Methylene Blue (MB) & Rhodamine B (RhB) and ammonium concentration were evaluated by using UV-Visible Spectroscopy. At 300°C, results showed complete removal for MB and more than 75% for RhB, whereas removal of ammonium ion reached around 52% when sintering product from husk waste was used. Further investigation was carried out for ammonium ion to understand the desorption kinetic behaviors and isotherm models. Kinetics indicated that desorption of ammonium ion followed pseudo-first order equation. Adsorption thermodynamic parameters such as ΔG, ΔH, and ΔS followed Van’t Hoff plot for adsorption and found to be negative which indicated that the adsorption process for ammonium onto coconut husk was physical, spontaneous and exothermic.
基金supported by the Jilin Provincial Natural Science Foundation(No.20240101118JC)the funds of Medical+X cross innovation team granted by medical department of Jilin University(No.2022JBGS07)+1 种基金the Jilin Province Science and Technology development project(No.20210101437JC)the WU JIEPING Medical Foundation(No.320.6750.2023-3-20 to TGM)。
文摘The cold sintering process(CSP)is a green and innovative method of material densification at low temperatures(<350°C).The traditional CSP entails the addition of liquid phases as a solvent to achieve material densification through the dissolution-precipitation mechanism.However,it is difficult to realize for materials with low solubility.To address this challenge,a universal cold sintering method without the addition of liquid phases has been proposed in this work.The addition of a special polyester-polymer assisted the densification of insoluble ceramics,and hydroxyapatite(HA)and Al_(2)O_(3)were successfully sintered below 100°C,achieving 95-100%densities in a short time(5-20 min).This achievement can be attributed to the low glass transition temperature and the abundance of active sites(C=O)of the polyester-polymer.The denser ceramics exhibited enhanced mechanical properties,with the compression strength of polymer-assisted CSP HA increasing by 147.3%compared to the nanoparticles.Additionally,serving as an advanced bone substitute material,HA underwent quantitative analysis using the CCK-8 method and assessed the impact of polymer presence on cell proliferation and cytotoxicity.Meanwhile,a tight bonding between the polymer and ceramic materials was achieved during CSP,providing a generalized method for designing multifunctional ceramic-polymer.
基金supported by the Key Research and Development Program of Gansu Province(22YF7FA070)the National Natural Science Foundation of China(22406076,22466026)the Basic Research Project of Yunnan Province(202301BE070001-017,202401CF070139,202401AS070085)。
文摘Iron and steel industry is one of the main sources of air pollution emissions in China.The sintering process is an important link in the blast furnace ironmaking process,but it is also accompanied by a large number of pollutants.Under the background of ultra-low emissions,iron and steel enterprises urgently need to upgrade their existing processes to address the existing process in practical application problems.In this study,a steel group in Gansu Province was taken as an example.By comparing and analyzing the pollutant emission characteristics before and after the ultra-low emission retrofit,the collaborative control effect of the combined process on SO_(2),NO_(x),particulate matter,and dioxins after the new retrofit was systematically evaluated.The results show that after the retrofit,the concentrations of particulate matter,SO_(2) and NO_(x) have dropped to near-zero levels,and the dioxin removal efficiency has reached 98.87%,with all indicators being better than the national ultra-low emission standards.The study confirms that the optimal combination of multi-pollutant collaborative treatment technologies is the key to achieving efficient emission reduction,among which selective catalytic reduction technology has a particularly significant synergistic removal effect on NO_(x) and dioxins.This study provides an important technical reference and practical basis for the ultra-low emission retrofit of the steel industry,and has important guiding significance for promoting the green retrofit of the industry.Its ultra-low emission retrofit is of great significance for achieving green and low-carbon development.
基金supported by the National Natural Science Foundation of China(No.51874368)。
文摘The use of high entropy alloy as a binder for tungsten heavy alloys offers potential advantages.The 95W-5CoCrFeMnNi alloys(95W-HEAs)were prepared via powder metallurgy at sintering temperatures of 1400−1550℃.The microstructure analysis revealed that the tungsten phase in 95W-HEAs exhibited a nearly spherical morphology in the HEA binder matrix and the formation of a Cr−Mn oxide mixed phase was observed.The sintering temperature exerted a significant influence on the relative density,grain size,W−W contiguity,and mechanical properties of the alloys.The optimal performance was achieved when sintering at 1450℃,yielding a relative density of 96.61%,a W−W contiguity of 0.528,an average grain size of 18.97μm,a compressive strength of 2234.82 MPa,and a hardness of HV 400.6.The activation energy for the diffusion of tungsten in the liquid phase formed by HEA binder was calculated to be 354.514 kJ/mol,highlighting its role in controlling grain growth.
基金Supported by National Natural Science Foundation of China(Grant Nos.52375466,51975504)Guangdong Provincial Basic and Applied Basic Research Foundation(Grant No.2022A1515110862)+1 种基金Jiangsu Provincial Key Laboratory of Precision and Micro-Manufacturing Technology(Grant No.JSKL2223K06)Hunan Provincial Excellent Youth Project of Education Department(Grant No.22B0109).
文摘Powder paving is an intermediate process of selective laser sintering(SLS).The dimensional accuracy and mechanical properties of sintered components are directly affected by the quality of the powder paving process,which is closely related to the flow characteristics of the powder and the process parameters of powder paving.This study investigated the simulation and optimization of the nylon powder paving in SLS by combining a discrete-element-method numerical simulation with a process test.A dynamic model was established to describe the flow and paving process of nylon powder at a preheating temperature considering mesoscopic van der Waals and electrostatic forces.The effects of the physical parameters and ambient temperature on the flow characteristics of nylon powder were analyzed,and the intrinsic relationship between the physical parameters of nylon powder,the process parameters of powder paving,and the quality of the powder paving were explored.A multi-objective regression model of the quality of powder paving was established using the response surface methodology,and a genetic algorithm was adopted to optimize the quality of the powder paving.A scientific and intelligent database of the nylon powder paving process in SLS was constructed by matching the process parameters of powder paving and physical parameters of the nylon powder,and the level of the SLS process was improved.
文摘This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C significantly improved the mechanical properties, including a notable 18.2% increase in hardness(HV 332). Fretting wear tests against 316L stainless steel(SS316L) balls demonstrated a 20wt%–22wt% reduction in wear volume in the Ti6Al4V/Ti C composites compared with the monolithic alloy. Microstructural analysis revealed that Ti C reinforcement controlled the grain orientation and reduced the β-phase content, which contributed to enhanced mechanical properties. The monolithic alloy exhibited a Widmanstätten lamellar microstructure, while increasing the Ti C content modified the wear mechanisms from ploughing and adhesion(0–0.5wt%) to pitting and abrasion(1wt%–2.5wt%). At higher reinforcement levels, the formation of a robust oxide layer through tribo-oxide treatment effectively reduced the wear volume by minimizing the abrasive effects and plastic deformation. This study highlights the potential of SPS-mediated Ti C reinforcement as a transformative approach for improving the performance of Ti6Al4V alloys, paving the way for advanced medical applications.
基金supported by the National Natural Science Foundation of China(Grant No.52474347)Postdoctoral Science Foundation of China(Grant No.2024T171095)the Fundamental Research Funds for the Central Universities(Grant No.2024CDJXY003).
文摘Coke oven gas(COG)and natural gas(NG),both high-calorific by-products derived from the steel industry,have gained prominence as alternative fuels in the sintering process,thereby supporting dual objectives of emission reduction and carbon neutrality.While existing research on hydrogen-rich gas injection has predominantly concentrated on conventional thin-bed sintering,investigations into its application within thick-bed sintering remain comparatively scarce.Thick-bed sintering,recognized for enhancing energy efficiency and increasing sinter output,encounters challenges such as uneven heat distribution and diminished permeability,which can negatively impact process efficiency and product quality.To address these issues,sinter pot experiments were conducted to assess the effects of NG and COG injection on thick-bed sintering performance.Findings reveal that NG injection in thick beds mirrors the behavior observed in conventional thin-bed sintering,effectively optimizing the process and achieving a carbon reduction potential exceeding 10%.In contrast,COG injection in thick-bed conditions demonstrates notable differences,substantially lowering the solid fuel consumption rate but detrimentally affecting sinter strength and overall production.However,by optimizing the timing of COG injection,it is feasible to improve sinter yield while concurrently reducing solid fuel usage.These outcomes provide valuable insights for the advancement of gas injection technologies in thick-bed sintering,thereby contributing to energy conservation and emission mitigation efforts within the sintering industry.
基金financially supported by Huxiang Youth Talent Program of Hunan Province(No.2024RC3008)National Natural Science Foundation China(Nos.52274343 and 52474370)National Key R&D Program of China(Nos.2023YFC3903900 and 2023YFC3903904).
文摘Sintering is a critical process in steel production that facilitates the efficient utilization of iron ore resources.However,compared to advanced sintering technologies,China’s sintering methods still exhibit high energy consumption,with typical solid fuel consumption for sintering of about 55 kg/t.In response,a pellet sintering process has been developed and its behavior has been investigated at sintering bed heights of 750 and 1500 mm.Additionally,a technical and economic comparison with traditional sintering methods has been conducted.The results indicate that at a bed height of 750 mm,the pellet sintering method can significantly reduce solid fuel consumption by approximately 30.82%,dropping from 70.75 to 48.95 kg/t.Additionally,the coke rate decreased from 4.55%to 3.20%,and harmful emissions in the flue gas were also reduced.As the bed height increases to 1500 mm,sintering performance improves even further.The coke rate is reduced to 3.00%,and solid fuel consumption decreases to 41.27 kg/t,approaching the world’s advanced level(≤40 kg/t).Technical and economic analysis also indicates that adopting the pellet sintering process can lower sintering costs by about 2.18 dollars/t.
基金Project(52274290)supported by the National Natural Science Foundation of ChinaProject(72088101)supported by the Basic Science Center Project for National Natural Science Foundation of China。
文摘A pre-reduction sintering process with flue gas recirculation(PSP_(fsg)-FGR)was developed to mitigate alkalis harm to the blast furnace and reduce the flue gas emission in the whole ironmaking process.The results indicated that the pre-reduction sintering process(PSP)can effectively remove 58.02%of K and 30.68%of Na from raw mixtures and improve yield and tumbler index to 74.40%and 68.69%,respectively.Moreover,PSP was conducive to reducing NO_(x) and SO_(2)emissions and simultaneously increasing CO content in flue gas.Circulating CO-containing flue gas to sintering bed effectively recycled CO and further improved K and Na removal ratio to 74.11%and 32.92%,respectively.Microstructural analysis revealed that the pre-reduced sinter mainly consisted of magnetite,wustite and a small quantity of metallic iron,and very few silicate glass phase was also formed.This process can simultaneously realize alkali metal elements removal as well as flue gas emission reduction from the integrated ironmaking process.
文摘By means of the synthetic approach of non－polar or weak polar oil－sorbed polymers，the gel sorption resin（GSR） and the multiporous sorption resin（MSR） were prepared．The structure of the resins，sorption power，sorption speed，desorption，and sorption of organic compounds from sewage，exhaust gas and soil were discussed．Moreover，the resins were used to decrease LOD and BOD5 values of water waste from sewage factory．Theyare a klndof potential materials for environmental control．
基金supported by the National Natural Science Foundation of China(No.51974131)Hebei Outstanding Youth Fund Project(No.E2020209082),Tangshan Key R&D Program project(No.22150232J)Sixth Division Wujiaqu City Science and Technology Plan Project(2410).
文摘During the sintering process of iron ore,a large amount of nitrogen oxides is generated,for which there is currently no efficient and economical treatment process.Therefore,it is necessary to implement process control in sintering production to keep the mass concentration of NO_(x)in sintering flue gas at a low level.Through industrial trials at sintering sites,methods such as correlation analysis,path analysis,and multiple linear regression were applied to analyze the influence of various factors on NO emissions during the sintering process.The results indicate that negative correlations exist between nitrogen monoxide(NO)emissions and negative pressure,permeability index,O_(2) concentration,CO concentration,and flue gas temperature.Conversely,positive correlations exist between NO emissions and dust concentration,water vapor volume fraction,and sintering bed speed.Among these factors,O_(2) concentration and dust concentration are identified as the most significant influencing factors on NO emissions.By analyzing the masses and modes of influence of different factors,the mechanisms of action of each factor were obtained.Specifically,O_(2) concentration,dust concentration,permeability index,CO concentration,and flue gas temperature play a direct dominant role in NO emissions during the sintering process,while water vapor volume fraction,sintering trolley speed,and negative pressure have an indirect effect.A predictive model for NO mass concentration in flue gas was established with an accuracy rate of 91.6%,showing consistent overall trends with actual values.Finally,denitrification strategies for sintering industrial production were proposed,along with prospects for preliminary denitrification of sintering flue gas using fluidized bed conditions in the duct.
基金supported by the National Key Research and Development Program of China(2022YFC3901405)the National Program for Supporting Postdoctoral Researchers of China(GZC20230016)the 2023 Provincial Quality Project Program for Nurturing People in the New Era(Graduate Education)(2023xscx065).
文摘Volatile organic compounds(VOCs)present significant risks to both human health and the environment.As a result,there has been increasing research on their formation processes,emission patterns,and emission reduction technologies.Sintered ore,a key raw material in ironmaking,requires substantial amounts of fossil fuels such as coal and coke in its production,leading to significant VOC emissions.However,research on VOC emission patterns during the sintering process remains limited.Thus,the influence of factors such as moisture content in the sintering mixture,fuel type,fuel ratio,and coal-to-coke ratio on VOC emissions was investigated through sintering cup experiments.Additionally,the reaction pathways of hydrocarbons within the sintering bed were analyzed using temperature distribution and thermodynamic calculations.In the sintering process using coke powder,the emissions of total volatile organic compounds and non-methane hydrocarbons per ton of sintered ore are 18.78 and 11.14 g,respectively,whereas emissions from coal are substantially higher at 378.27 and 32.55 g.VOC emissions exhibit a linear correlation with the total volatile matter input during sintering,with most VOCs originating from volatile matter.The improved heat transfer conditions reduce the preheating zone thickness,allowing more VOCs to remain in the high-temperature region.
基金supported by the National Natural Science Foundation of China(52204331)Natural Science Foundation of Anhui Province Youth Project(2208085QE145)the Open Project Program of Key Laboratory of Metallurgical Emission Reduction&Resources Recycling(Anhui University of Technology),Ministry of Education(JKF20-03).
文摘Steel rolling sludge,an oil-containing waste generated during steel production,was difficult to manage.Prolonged storage poses significant environmental and health hazards.Most steel enterprises in China use steel rolling sludge directly as a raw material for sintering.However,its adhesive nature caused poor mixing with other materials,affecting the quality of the sinter.Herein,the incorporation of steel rolling sludge incineration slag into the sintering process was investigated for experimental purposes.The results indicated that adding 1%incinerated steel rolling sludge to the sintering raw material was feasible.At this proportion,both the yield and the tumbler index of the sinter have improved,primarily due to the oxidation reaction of Fe_(3)O_(4)present in the steel rolling sludge incineration slag during the sintering process,which significantly increases the sensible heat of the sinter and enhances the sintering mineralization reaction.Notably,the addition of steel rolling sludge incineration slag reduced dioxin concentrations in the sintering flue gas.Although CO,NO_(x),and SO_(2)emission concentrations slightly increased,the existing flue gas treatment system effectively controlled their emissions.
基金supported by the Frontier Science Key Program of the Chinese Academy of Sciences(No.QYZDY-SSW-JSC016)Chinese Academy of Sciences President’s International Fellowship Initiative(No.2024VMA0012).
文摘Yttrium hydride(YH_(x))is a highly promising neutron moderator material for nuclear reactors,known for its exceptional thermal stability and high hydrogen content.This study investigated the sintering mechanism and microstructural evolution of YH_(x)monoliths processed by spark plasma sintering(SPS),with the effects of temperature,duration,and pressure.The results indicate that the sintering process can be divided into five stages:formation of sintering necks,rapid densification,anti-densification,recrystallization,and grain growth.The anti-densification behavior is attributed to hydrogen desorption,phase transformation-induced volumetric contraction,and vacancy coalescence from hydrogen migration,leaving residual pores and lattice defects.Furthermore,increasing the sintering temperature and duration promotes recrystallization and grain growth,whereas elevated pressure effectively suppresses grain boundary migration.This research establishes fundamental processing-structure correlations critical for optimizing YHx moderators in nuclear applications.
基金supported by the General Program of the National Natural Science Foundation of China(No.52274326)the China Baowu Low Carbon Metallurgy Innovation Foundation(No.BWLCF202109)the Seventh Batch of Ten Thousand Talents Plan of China(No.ZX20220553).
文摘Sinter is the core raw material for blast furnaces.Flue pressure,which is an important state parameter,affects sinter quality.In this paper,flue pressure prediction and optimization were studied based on the shapley additive explanation(SHAP)to predict the flue pressure and take targeted adjustment measures.First,the sintering process data were collected and processed.A flue pressure prediction model was then constructed after comparing different feature selection methods and model algorithms using SHAP+extremely random-ized trees(ET).The prediction accuracy of the model within the error range of±0.25 kPa was 92.63%.SHAP analysis was employed to improve the interpretability of the prediction model.The effects of various sintering operation parameters on flue pressure,the relation-ship between the numerical range of key operation parameters and flue pressure,the effect of operation parameter combinations on flue pressure,and the prediction process of the flue pressure prediction model on a single sample were analyzed.A flue pressure optimization module was also constructed and analyzed when the prediction satisfied the judgment conditions.The operating parameter combination was then pushed.The flue pressure was increased by 5.87%during the verification process,achieving a good optimization effect.
基金the National Key Research and Development Program of China(2017YFB0304301)the Fundamental Research Funds for the Central Universities of Central South University(No.202044016).
文摘Poor permeability and low sintering productivity restrict the development of high-bed sintering.An efficient method of the double-layer sintering process(DLSP)was proposed to achieve high-bed sintering and solve the aforementioned problems.Theoretical calculation and sintering pot experiments were implemented to investigate the double-layer sintering process.Traditional sintering process and DLSP were compared in terms of sintering indices,metallurgical properties and morphology characterization.Under the condition of traditional sintering process,DLSP successfully realized fast velocity and highly productive sintering of 1000-mm high bed.After the sintering bed is charged and ignited twice,the air permeability of the bed has been greatly improved.Sintering time is shortened significantly by simultaneous sintering of the upper and lower feed layers.Under the condition of bed height proportion of 350/650 mm and pre-sintering time of 20 min,the yield,tumbler strength,productivity and solid fuel consumption are 69.96%,65.87%,1.71 t(m^(2)h)^(-1)and 56.71 kg/t,respectively.Magnetite,hematite,calcium ferrite and complex calcium ferrite are the main phases of DLSP products.The metallurgical properties of DSLP products meet the requirement of ironmaking.It indicates that DLSP is an effective method to solve the disadvantages of bad permeability and low sintering productivity in high-bed sintering.
基金financially supported by the National Nat-ural Science Foundation of China(Nos.U22A20185,52175302,and U21A20128)the National MCF Energy R&D Program(No.2019YFE03100100)the Fundamental Research Funds for the Central Universities(No.2022FRFK060009).
文摘The challenge of low temperature and rapid diffusion bonding of a Ni-based superalloy was hereby addressed by using a Ni nano-coating and a spark plasma sintering(SPS).It successfully produced a Nibased superalloy joint with 337 MPa shear strength at 500℃ for 30 min,which is approximately 400℃ lower than the traditional hot pressure diffusion bonding(HPDB)temperature.The microstructure and mechanical properties of the joints were systematically investigated.It is revealed that the pulsed current and ultra-fine grains(19 nm)in the Ni nano-coating could significantly facilitate voids closure.The voids closure mechanisms involved(i)pulsed current strengthened plastic deformation,(ii)pulsed current strengthened surface source diffusion,(iii)pulsed current strengthened bonding interface diffusion,(iv)grain growth dividing the initial large voids into nano-voids,and(v)massive grain boundaries(GBs),lattice defects,and local high-temperature strengthened GBs diffusion.Furthermore,the GBs migration across the interface was investigated,and the results revealed that the GBs migration and fine grains(350 nm)near the bonding interface together increased the joint strength.
基金supported by the Basic Science Center Project for the National Natural Science Foundation of China(No.72088101)the S&T Program of Hebei(No.23564101D).
文摘As the bed depth increases,sintering yield increases,but the productivity decreases.To reveal the reasons for the decrease in productivity and explore targeted solutions,the bed resistance of mixtures,wet zone,and combustion zone was analyzed in the laboratory.The results showed that the decreased porosity of mixture resulted in the increased bed resistance by 160.56%when the bed depth increased from 600 to 1000 mm.After improving porosity of 1%by adding loosening bars with optimized size and distribution,the bed resistance decreased,and the productivity increased by 5%.The increase in bed depth increased the thickness of the wet zone from 120 to 680 mm and the resistance from 1.56 to 8.83 kPa.By using a three-stage intensive mixer and pre-adding water for granulation,the moisture of mixture was reduced by 0.6%,and the sintering productivity increased by 4%.Besides,the high bed resistance is mainly caused by the increase in the thickness of the combustion zone from 31.9 to 132.7 mm,and the bed resistance increased from 0.70 to 5.62 kPa.The bed resistance of the combustion zone at 900 mm was increased by 90.51%compared to 700 mm.After optimization of the distribution of coke breeze,the thickness of combustion zone at the lower layer decreased from 132.7 to 106.84 mm and permeability improved significantly.
文摘A key component of future lunar missions is the concept of in-situ resource utilization(ISRU),which involves the use of local resources to support human missions and reduce dependence on Earth-based supplies.This paper investigates the thermal processing capability of lunar regolith without the addition of binders,with a focus on large-scale applications for the construction of lunar habitats and infrastructure.The study used a simulant of lunar regolith found on the Schr?dinger Basin in the South Pole region.This regolith simulant consists of20 wt%basalt and 80 wt%anorthosite.Experiments were conducted using a high power CO_(2)laser to sinter and melt the regolith in a 80 mm diameter laser spot to evaluate the effectiveness of direct large area thermal processing.Results indicated that sintering begins at approximately 1180℃and reaches full melt at temperatures above 1360℃.Sintering experiments with this material revealed the formation of dense samples up to 11 mm thick,while melting experiments successfully produced larger samples by overlapping molten layers and additive manufacturing up to 50 mm thick.The energy efficiency of the sintering and melting processes was compared.The melting process was about 10 times more energy efficient than sintering in terms of material consolidation,demonstrating the promising potential of laser melting technologies of anorthosite-rich regolith for the production of structural elements.
