The iron ore sintering process is the main source of SO_2 emissions in the iron and steel industry. In our previous research, we proposed a novel technology for reducing SO_2 emissions in the flue gas in the iron ore ...The iron ore sintering process is the main source of SO_2 emissions in the iron and steel industry. In our previous research, we proposed a novel technology for reducing SO_2 emissions in the flue gas in the iron ore sintering process by adding urea at a given distance from the sintering grate bar. In this paper, a pilot-scale experiment was carried out in a commercial sintering plant. The results showed that, compared to the SO_2 concentration in flue gas without urea addition, the SO_2 concentration decreased substantially from 694.2 to 108.0 mg/m^3 when 0.10wt% urea was added. NH_3 decomposed by urea reacted with SO_2 to produce（NH_4）_2SO_4, decreasing the SO_2 concentration in the flue gas.展开更多
It is of great significance for cleaner production to substitute bio-energy for fossil fuels in iron ore sintering. However, with the replacement ratio increasing, the consistency of heat front and flame front is brok...It is of great significance for cleaner production to substitute bio-energy for fossil fuels in iron ore sintering. However, with the replacement ratio increasing, the consistency of heat front and flame front is broken, and the thermal utilizing efficiency of fuel is reduced, which results in the decrease of yield and tumble index of sinter. Circulating flue gas to sintering bed as biochar replacing 40% coke, CO in flue gas can be reused so as to increase the thermal utilizing efficiency of fuels, and the consistency of two fronts is recovered for the circulating flue gas containing certain CO2, H2 O and lower O2, which contributes to increasing the maximum temperature, extending the high temperature duration time of sintering bed, and results in improving the output and quality of sinter. In the condition of circulating 40% flue gas, the sintering with biomass fuels is strengthened, and the sintering indexes with biomass fuel replacing 40% coke breeze are comparative to those of using coke breeze completely.展开更多
Waste selective catalytic reduction(SCR)catalyst as a hazardous waste has a significant impact on the environment and human health.In present study,a novel technology for thermal treatment of waste SCR catalyst was pr...Waste selective catalytic reduction(SCR)catalyst as a hazardous waste has a significant impact on the environment and human health.In present study,a novel technology for thermal treatment of waste SCR catalyst was proposed by adding it to sinter mix for iron ore sintering.The influences of coke rate on the flame front propagation,sinter microstructure,and sinter quality during sintering co-processing the waste SCR catalyst process were studied.In situ tests results indicated the maximum sintering bed temperature increased at higher coke rate,indicating more liquid phase generated and higher airflow resistance.The sintering time was longer and the calculated flame front speed dropped at higher coke rate.Sinter microstructure results found the coalescence and reshaping of bubbles were more fully with increasing coke rate.The porosity dropped from 35.28%to 25.66%,the pore average diameter of large pores decreased from 383.76μm to 311.43μm.With increasing coke rate,the sinter indexes of tumbler index,productivity,and yield,increased from 33.2%,9.2 t·m^(-2)·d^(-1),28.9%to 58.0%,36.0 t·m^(-2)·d^(-1),68.9%,respectively.Finally,a comprehensive index was introduced to systematically assess the influence of coke rate on sinter quality,which rose from 100 to 200 when coke rate was increased from 3.5%(mass)to 5.5%(mass).展开更多
The energy consumption of iron ore sintering process is about 10%- 15%of the total of iron and steel industry.Therefore,it is of great significance to take effective measures to reduce the energy consumption in the ir...The energy consumption of iron ore sintering process is about 10%- 15%of the total of iron and steel industry.Therefore,it is of great significance to take effective measures to reduce the energy consumption in the iron ore sintering process to reduce the costs of sintering product and cut down the emissions of harmful gases,such as CO_2 and SO_2.In this study,the technology development of saving energy and reducing emission in iron ore sintering process was reviewed and discussed;some new directions and measures of saving energy were presented for the sintering process in the future.展开更多
Sinter body strength, which reflects the strength of sinter, plays an important role in the improvement of sinter. In this study, the sinter body strengths of iron ores were measured using a microsintering method. The...Sinter body strength, which reflects the strength of sinter, plays an important role in the improvement of sinter. In this study, the sinter body strengths of iron ores were measured using a microsintering method. The relationship between the chemical composition and sinter body strength was discussed. Moreover, sinter-pot tests were performed. The effects of sinter body strength on the sintering indexes were then elucidated, and the bottom limit of sinter body strength of blending ores was confirmed. In the results, the compressive strengths（CSs） of iron ores are observed to decrease with the increasing of the contents of loss on ignition（LOI）, SiO 2, and Al2O3; however, LOI of less than 3wt% does not substantially influence the CSs of fine ores. In the case of similar mineral composition, the porosity, in particular, the ratio between the number of large pores and the total number of pores, strongly influences the sinter body strength. With an increase of the blending-ore CSs used in sinter-pot tests, the yield, productivity, and tumbler strength increase, and the solid fuel consumption decreases. The CSs of the blending ores only slightly affect the sintering time. The CS bottom limit of the blending ores is 310 N. When the CSs of the blending ores increase by 10%, the yield, productivity, and tumbler index increase by 1.9%, 2.8%, and 2.0%, respectively, and the solid fuel consumption decreases by 1.9%.展开更多
Zinc extraction residue,a solid waste generated from the treatment of zinc-containing dust in rotary kilns,is commonly stockpiled in steel companies for extended periods.It poses significant disposal challenges and en...Zinc extraction residue,a solid waste generated from the treatment of zinc-containing dust in rotary kilns,is commonly stockpiled in steel companies for extended periods.It poses significant disposal challenges and environmental pollution risks.So far,research on the treatment of zinc extraction residues has been slow,inadequate,and sporadic.For this gap,a novel approach was proposed to effectively treat the zinc extraction residue via the iron ore sintering process.It was feasible to add 1 wt.%of zinc extraction residues to the sintering raw materials.The more adequate mineralization reaction resulted in higher yield and tumbler indexes,despite a slight decrease in sintering speed.Although this may result in a slight decrease in sintering speed,the more complete mineralization reaction leads to improved sintering yield and tumbler index.Interestingly,the addition of zinc extraction residues reduced the CO and NO_(x) concentrations in the sintering flue gas.Thus,the iron ore sintering process provided a viable solution for resource utilization and environmentally friendly treatment of zinc extraction residues.展开更多
Benzene is a typical component of volatile organic compounds(VOCs)in the iron ore sintering flue gas.The combustion behavior of benzene directly affects the emission of VOCs in iron ore sintering process.The effects o...Benzene is a typical component of volatile organic compounds(VOCs)in the iron ore sintering flue gas.The combustion behavior of benzene directly affects the emission of VOCs in iron ore sintering process.The effects of temperature,benzene,and oxygen concentrations on the conversion ratio of benzene were investigated by experiments and numerical simulation.The experiments were carried out in a tube reactor at temperatures of 773-1098 K,benzene concentrations of 0.01-0.03 vol.%,and oxygen concentrations of 10-21 vol.%.The numerical simulation was performed with the plug flow model in the CHEMKIN program based on a kinetic model that consists of 132 chemical species and 772 elementary step-like reactions.The experimental results reveal that increasing the temperature and benzene concentration could signifi-cantly promote benzene combustion.It is attributed to the increase in the reaction rates of all steps in the pathway for forming CO_(2)and H_(2)O.In addition,due to the large equivalent ratio of oxygen to benzene,the conversion ratio of benzene remained constant at different oxygen concentrations.The simulation results were in good agreement with the experimental results and indicated that six elementary reactions dominated the formations of CO_(2)and H_(2)O.The oxidations of C_(6)H_(5)O,CO,and C_(5)H_(4)O intermediates to CO_(2)were the limiting steps in the reaction pathways.展开更多
To better understand the evolution characteristics of bed porous structure during iron ore sintering,X-ray computed tomography scanning technology was used to analyze the pore parameters in different areas of the sint...To better understand the evolution characteristics of bed porous structure during iron ore sintering,X-ray computed tomography scanning technology was used to analyze the pore parameters in different areas of the sintering bed.A pore skeleton structure model was established to study the characteristics of the airflow channels in different zones.The absolute permeability of different areas was calculated through simulation,and the corresponding streamline and pressure drop distribution were analyzed.The results show that the porosity of raw material zone,high-temperature zone,and sintered zone increases gradually,which are 37.69%,46.41%,and 55.57%,respectively.The absolute permeability calculation results of the raw material zone and sintered zones are 792.49μm^(2) and 20560.80μm^(2),while the tortuosity is 1.77 and 1.45,respectively.Compared with the raw material zone,the flow streamline in the sintered zone is thicker and denser,the airflow resistance and the pressure drop are minor.展开更多
The emission of dioxins from the iron ore sintering process is the largest emission source of dioxins, and the reduction in dioxin emission from the iron ore sintering process to the environment is increasingly import...The emission of dioxins from the iron ore sintering process is the largest emission source of dioxins, and the reduction in dioxin emission from the iron ore sintering process to the environment is increasingly important. Three approaches to control the emission of dioxins were reviewed： source control, process control, and terminal control. Among them, two terminal control technologies, activated carbon adsorption and selective reduction technology, were discussed in detail. Following a comparison of the reduction technologies, the terminal control method was indicated as the key technology to achieve good control of dioxins during the sintering process. For the technical characteristics of the sintering process and flue gas, multiple methods should be collectively considered, and the most suitable method may be addition of inhibitors ＋ ultra-clean dust collection （electrostatic precipitation/bag filter） ＋ desulphurization ＋ selective catalytic reduction to sufficiently remove multiple pollutants, which provides a direction for the cooperative disposal of flue gas pollutants in future.展开更多
As the emission control regulations get stricter,the NO;reduction in the sintering process becomes an important environmental concern owing to its role in the formation of photochemical smog and acid rain.The NOxemiss...As the emission control regulations get stricter,the NO;reduction in the sintering process becomes an important environmental concern owing to its role in the formation of photochemical smog and acid rain.The NOxemissions from the sintering machine account for 48% of total amount from the iron and steel industry.Thus,it is essential to reduce NO;emissions from the sintering machine,for the achievement of clean production of sinter.Ca-Fe oxides,serving as the main binding phase in the sinter,are therefore used as additives into the sintering mixture to reduce NOxemissions.The results show that the NO;reduction ratio achieves 27.76% with 8% Ca-Fe oxides additives since the Ca-Fe oxides can advance the ignition and inhibit the nitrogen oxidation compared with the conventional condition.Meanwhile,the existence of Ca-Fe oxides was beneficial to the sinter quality since they were typical low melting point compounds.The optimal mass fraction of Ca-Fe oxides additives should be less than 8%since the permeability of sintering bed was significantly decreased with a further increase of the Ca-Fe oxides fines,inhibiting the mineralization reaction of sintering mixture.Additionally,the appropriate particle size can be obtained when mixing an equal amount of Ca-Fe oxides additives of-0.5 mm and 0.5-3.0 mm in size.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
Canadian iron concentrate(CIC)can elevate the ferrous grade and lower the contents of gangue components and harmful elements in the sinter.To understand high-temperature characteristics of CIC and typical iron ore,the...Canadian iron concentrate(CIC)can elevate the ferrous grade and lower the contents of gangue components and harmful elements in the sinter.To understand high-temperature characteristics of CIC and typical iron ore,the formation of the melt was calculated mainly through FactSage 7.2,and melt fluidity(MF)test for iron ore fines and penetration characteristic test of CIC melt into iron ore nuclei were carried out via micro-sintering method.The results show that hematite,calcium ferrites,dicalcium silicate,and magnetite take part in the formation of the melt in N2.The formation temperature of the liquid for CIC is higher than that for hematite/limonite ore.The MF of CIC is lower than that of hematite/limonite ore fines.The MF of hematite/limonite ore fines is dominated by the liquid amount and melt viscosity.The penetration depth(PD)of CIC melt into limonite ore nuclei is smaller than that into hematite ore nuclei.The PD is related to the reaction ability of the nuclei with the melt.Based on above results,sinter pot tests were conducted.The result shows that in the base ore blends including two hematite ores and two limonite ores,adding CIC deteriorates the sintering indexes.Increasing the proportion of high-MF and small-PD hematite ore can significantly improve the sintering indexes.10 mass%is a suit-able proportion for adding CIC in ore blends.展开更多
The strength properties of green sinter beds,including the Young’s modulus and maximum bed strain,were evaluated using uniaxial compression tests.The green-sinter-bed samples were scanned using X-ray computed tomogra...The strength properties of green sinter beds,including the Young’s modulus and maximum bed strain,were evaluated using uniaxial compression tests.The green-sinter-bed samples were scanned using X-ray computed tomography(XCT),and the geometry characteristics of the granules were quantified by XCT image analysis.The orthogonal array method was applied to determine the concomitant effects of the moisture,hydrated lime,and concentrate contents on the bed strength characteristics.Less bed strain was observed when the granules had a thin adhering layer and increased interlock contacts,which had a great capacity to resist the applied load collectively.The optimal combination for decreasing the bed maximum strain was 5.8%moisture,2%hydrated lime,and 0%concentrate.The moisture and concentrate contents were the most significant factors determining the green bed strength.Increasing the moisture and concentrate contents produced granules with a thicker and more deformable adhering layer,resulting in a more compact bed.The addition of hydrated lime inhibited rearrangement,deformation,and fracture of the granules in green sinter bed during compression.展开更多
The activated carbon injection-circulating fluidized bed（ACI-CFB）-bag filter coupling technique was studied in an iron ore sintering plant. For comparison, the removal efficiencies under the conditions without or wi...The activated carbon injection-circulating fluidized bed（ACI-CFB）-bag filter coupling technique was studied in an iron ore sintering plant. For comparison, the removal efficiencies under the conditions without or with ACI technology were both evaluated. It was found that the polychlorinated dibenzo-p-dioxins and dibenzofuran（PCDD/F） removal efficiency for total international toxic equivalence quantity（I-TEQ） concentration was improved from 91.61% to 97.36% when ACI was employed, revealing that ACI was very conducive to further controlling the PCDD/F emissions. Detailed congener distributions of PCDD/Fs in the gas-phase and particle-phase of the Inlet and Outlet samples were determined. Additionally, the PCDD/F distribution for the Fly ash-with ACI sample of was also studied.展开更多
A model of iron ore sintering was built with consideration of fuel combustion, catalysis of sinter mixture as well as formation of melt and mineral, which was verified via sintering pot tests and showed a good fit to ...A model of iron ore sintering was built with consideration of fuel combustion, catalysis of sinter mixture as well as formation of melt and mineral, which was verified via sintering pot tests and showed a good fit to the experi- mental results. The effect of bed depth on temperature was reflected by the residence time in high-temperature zone, rather than the top value of the temperature, which was weakened by melt formation as well as hematite decomposi- tion. Moreover, the effect of bed depth, fuel content and distribution on sintering process was different, which was reflected by temperature profiles and the rule of calcium ferrite formation. The formation of melt as well as magnetite was a process which was decided by kinetic factors, while the formation of calcium ferrite was related to fuel blend- ing conditions, which is determined by thermodynamics when the fuel ratio inside sinter granules is low or fuel con- tent is high, otherwise, it is determined by kinetics.展开更多
The iron oxide(FeO)content had a significant impact on both the metallurgical properties of sintered ores and the economic indicators of the sintering process.Precisely predicting FeO content possessed substantial pot...The iron oxide(FeO)content had a significant impact on both the metallurgical properties of sintered ores and the economic indicators of the sintering process.Precisely predicting FeO content possessed substantial potential for enhancing the quality of sintered ore and optimizing the sintering process.A multi-model integrated prediction framework for FeO content during the iron ore sintering process was presented.By applying the affinity propagation clustering algorithm,different working conditions were efficiently classified and the support vector machine algorithm was utilized to identify these conditions.Comparison of several models under different working conditions was carried out.The regression prediction model characterized by high precision and robust stability was selected.The model was integrated into the comprehensive multi-model framework.The precision,reliability and credibility of the model were validated through actual production data,yielding an impressive accuracy of 94.57%and a minimal absolute error of 0.13 in FeO content prediction.The real-time prediction of FeO content provided excellent guidance for on-site sinter production.展开更多
Resistance in iron ore undergoes a sharp change of up to several orders of magnitude when the sintered solid phase changes to liquid phase.In view of the insufficiency of existing assimilation detection methods,a timi...Resistance in iron ore undergoes a sharp change of up to several orders of magnitude when the sintered solid phase changes to liquid phase.In view of the insufficiency of existing assimilation detection methods,a timing-of-assimilation reaction is proposed,which was judged by continuously detecting the changes in resistance at the reaction interface.Effects of pole position and additional amounts of iron ore on assimilation reaction timing were investigated.The results showed that the suitable depth of pole groove was about 2 mm,and there was no obvious impact when the distance of the poles changed from 4 to 6 mm,or the amount of iron ore changed from 0.4 to 0.6 g.The temperature of sudden change of resistance in the temperature-resistant image was considered to be the lowest assimilation temperature of iron ore.The accuracy of this resistance method was clarified by X-ray diffraction,optical microscope,and scanning electron microscope/energy dispersive spectrometer(SEM/EDS)analyses.展开更多
The influence of ammonia and Brown gas injection on the iron ore sintering characteristics was explored through sintering pot experiments based on biochar substitution to increase biochar substitution proportion and r...The influence of ammonia and Brown gas injection on the iron ore sintering characteristics was explored through sintering pot experiments based on biochar substitution to increase biochar substitution proportion and reduce fossil energy consumption.By dividing the high-temperature stage of the sintering bed,the heating rate and cooling rate were calculated,and the reasons for poor sintering quality under a high biochar substitution ratio were explored.The results showed that under the 40%biochar substitution ratio,the cooling rate of the sintering bed significantly increased,the high-temperature duration time was short,and the sintering quality deteriorated severely.Additional injection of 0.5–1%vol ammonia or 1–2%vol Brown gas can reduce the cooling rate,prolong the high-temperature duration,and optimize the sintering quality.Based on 1%vol ammonia or 2%vol Brown gas injection,reducing the proportion of biochar with equal calorific value further increases the sintering comprehensive index,which means that using 1%vol ammonia or 2%vol Brown gas injection to assist sintering can reduce the proportion of coke usage to 60%,while the proportion of biochar substitution is 33.76%and 32.47%,respectively.The research results provide an effective solution for low-carbon sintering.展开更多
Process control is an effective approach to reduce the NOx emission from sintering flue gas.The effects of different materials adhered on coke breeze on NOx emission characteristics and sintering performance were stud...Process control is an effective approach to reduce the NOx emission from sintering flue gas.The effects of different materials adhered on coke breeze on NOx emission characteristics and sintering performance were studied.Results showed that the coke breeze adhered with the mixture of CaO and Fe2O3 or calcium ferrite significantly lowers the NOx emission concentration and conversion ratio of fuel-N to NOx.Pretreating the coke with the mixture of lime slurry and iron ore fines helped to improve the granulation effect,and optimize the carbon distribution in granules.When the mass ratio of coke breeze,quick lime,water and iron ore fines was 2:1:1:1,the average NOx emission concentration was decreased from 220 mg/m3 to 166 mg/m3,and the conversion ratio of fuel-N was reduced from 54.2%to 40.9%.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.U1260101 and 51504003)the Project of Science and Technology Development of Anhui Province,China (No.1501041126)
文摘The iron ore sintering process is the main source of SO_2 emissions in the iron and steel industry. In our previous research, we proposed a novel technology for reducing SO_2 emissions in the flue gas in the iron ore sintering process by adding urea at a given distance from the sintering grate bar. In this paper, a pilot-scale experiment was carried out in a commercial sintering plant. The results showed that, compared to the SO_2 concentration in flue gas without urea addition, the SO_2 concentration decreased substantially from 694.2 to 108.0 mg/m^3 when 0.10wt% urea was added. NH_3 decomposed by urea reacted with SO_2 to produce（NH_4）_2SO_4, decreasing the SO_2 concentration in the flue gas.
基金Projects(51174253,51304245) supported by National Natural Science Foundation of China
文摘It is of great significance for cleaner production to substitute bio-energy for fossil fuels in iron ore sintering. However, with the replacement ratio increasing, the consistency of heat front and flame front is broken, and the thermal utilizing efficiency of fuel is reduced, which results in the decrease of yield and tumble index of sinter. Circulating flue gas to sintering bed as biochar replacing 40% coke, CO in flue gas can be reused so as to increase the thermal utilizing efficiency of fuels, and the consistency of two fronts is recovered for the circulating flue gas containing certain CO2, H2 O and lower O2, which contributes to increasing the maximum temperature, extending the high temperature duration time of sintering bed, and results in improving the output and quality of sinter. In the condition of circulating 40% flue gas, the sintering with biomass fuels is strengthened, and the sintering indexes with biomass fuel replacing 40% coke breeze are comparative to those of using coke breeze completely.
基金supported by the National Natural Science Foundation of China(52036008).
文摘Waste selective catalytic reduction(SCR)catalyst as a hazardous waste has a significant impact on the environment and human health.In present study,a novel technology for thermal treatment of waste SCR catalyst was proposed by adding it to sinter mix for iron ore sintering.The influences of coke rate on the flame front propagation,sinter microstructure,and sinter quality during sintering co-processing the waste SCR catalyst process were studied.In situ tests results indicated the maximum sintering bed temperature increased at higher coke rate,indicating more liquid phase generated and higher airflow resistance.The sintering time was longer and the calculated flame front speed dropped at higher coke rate.Sinter microstructure results found the coalescence and reshaping of bubbles were more fully with increasing coke rate.The porosity dropped from 35.28%to 25.66%,the pore average diameter of large pores decreased from 383.76μm to 311.43μm.With increasing coke rate,the sinter indexes of tumbler index,productivity,and yield,increased from 33.2%,9.2 t·m^(-2)·d^(-1),28.9%to 58.0%,36.0 t·m^(-2)·d^(-1),68.9%,respectively.Finally,a comprehensive index was introduced to systematically assess the influence of coke rate on sinter quality,which rose from 100 to 200 when coke rate was increased from 3.5%(mass)to 5.5%(mass).
文摘The energy consumption of iron ore sintering process is about 10%- 15%of the total of iron and steel industry.Therefore,it is of great significance to take effective measures to reduce the energy consumption in the iron ore sintering process to reduce the costs of sintering product and cut down the emissions of harmful gases,such as CO_2 and SO_2.In this study,the technology development of saving energy and reducing emission in iron ore sintering process was reviewed and discussed;some new directions and measures of saving energy were presented for the sintering process in the future.
基金financially supported by the Fundamental Research Funds for the Central Universities of China (No. FRF-IC-14-006)
文摘Sinter body strength, which reflects the strength of sinter, plays an important role in the improvement of sinter. In this study, the sinter body strengths of iron ores were measured using a microsintering method. The relationship between the chemical composition and sinter body strength was discussed. Moreover, sinter-pot tests were performed. The effects of sinter body strength on the sintering indexes were then elucidated, and the bottom limit of sinter body strength of blending ores was confirmed. In the results, the compressive strengths（CSs） of iron ores are observed to decrease with the increasing of the contents of loss on ignition（LOI）, SiO 2, and Al2O3; however, LOI of less than 3wt% does not substantially influence the CSs of fine ores. In the case of similar mineral composition, the porosity, in particular, the ratio between the number of large pores and the total number of pores, strongly influences the sinter body strength. With an increase of the blending-ore CSs used in sinter-pot tests, the yield, productivity, and tumbler strength increase, and the solid fuel consumption decreases. The CSs of the blending ores only slightly affect the sintering time. The CS bottom limit of the blending ores is 310 N. When the CSs of the blending ores increase by 10%, the yield, productivity, and tumbler index increase by 1.9%, 2.8%, and 2.0%, respectively, and the solid fuel consumption decreases by 1.9%.
基金supported by the National Natural Science Foundation of China (52204331)Natural Science Foundation of Anhui Province Youth Project (2208085QE145)Open Fund of Key Laboratory of Metallurgical Emission Reduction and Resource Utilization,Ministry of Education (JKF20-03).
文摘Zinc extraction residue,a solid waste generated from the treatment of zinc-containing dust in rotary kilns,is commonly stockpiled in steel companies for extended periods.It poses significant disposal challenges and environmental pollution risks.So far,research on the treatment of zinc extraction residues has been slow,inadequate,and sporadic.For this gap,a novel approach was proposed to effectively treat the zinc extraction residue via the iron ore sintering process.It was feasible to add 1 wt.%of zinc extraction residues to the sintering raw materials.The more adequate mineralization reaction resulted in higher yield and tumbler indexes,despite a slight decrease in sintering speed.Although this may result in a slight decrease in sintering speed,the more complete mineralization reaction leads to improved sintering yield and tumbler index.Interestingly,the addition of zinc extraction residues reduced the CO and NO_(x) concentrations in the sintering flue gas.Thus,the iron ore sintering process provided a viable solution for resource utilization and environmentally friendly treatment of zinc extraction residues.
基金This work was supported by the National Natural Science Foundation of China(Nos.51904127 and 51166004)Key R&D Program of Jiangxi Province(Nos.20202BBGL73117 and 20201BBE51013)+2 种基金Nanchang Key Laboratory(No.2021-NCZDSY-020)Pilot Demonstration Project for the Contract Responsibility System of the Provincial Science and Technology Plan Project of Jiangxi Academy of Sciences(Nos.2021YSBG21015,2022YSBG50010 and 2023YSTZX02)Open Project of Jiangxi Zhongke Ecological Civilization Innovation Research Institute(No.JXZK-2020-01).
文摘Benzene is a typical component of volatile organic compounds(VOCs)in the iron ore sintering flue gas.The combustion behavior of benzene directly affects the emission of VOCs in iron ore sintering process.The effects of temperature,benzene,and oxygen concentrations on the conversion ratio of benzene were investigated by experiments and numerical simulation.The experiments were carried out in a tube reactor at temperatures of 773-1098 K,benzene concentrations of 0.01-0.03 vol.%,and oxygen concentrations of 10-21 vol.%.The numerical simulation was performed with the plug flow model in the CHEMKIN program based on a kinetic model that consists of 132 chemical species and 772 elementary step-like reactions.The experimental results reveal that increasing the temperature and benzene concentration could signifi-cantly promote benzene combustion.It is attributed to the increase in the reaction rates of all steps in the pathway for forming CO_(2)and H_(2)O.In addition,due to the large equivalent ratio of oxygen to benzene,the conversion ratio of benzene remained constant at different oxygen concentrations.The simulation results were in good agreement with the experimental results and indicated that six elementary reactions dominated the formations of CO_(2)and H_(2)O.The oxidations of C_(6)H_(5)O,CO,and C_(5)H_(4)O intermediates to CO_(2)were the limiting steps in the reaction pathways.
基金supported by National Natural Science Foundation of China (grant No.52036008).
文摘To better understand the evolution characteristics of bed porous structure during iron ore sintering,X-ray computed tomography scanning technology was used to analyze the pore parameters in different areas of the sintering bed.A pore skeleton structure model was established to study the characteristics of the airflow channels in different zones.The absolute permeability of different areas was calculated through simulation,and the corresponding streamline and pressure drop distribution were analyzed.The results show that the porosity of raw material zone,high-temperature zone,and sintered zone increases gradually,which are 37.69%,46.41%,and 55.57%,respectively.The absolute permeability calculation results of the raw material zone and sintered zones are 792.49μm^(2) and 20560.80μm^(2),while the tortuosity is 1.77 and 1.45,respectively.Compared with the raw material zone,the flow streamline in the sintered zone is thicker and denser,the airflow resistance and the pressure drop are minor.
基金The authors acknowledge financial support from the Key Project of National Natural Science Foundation of China（U1660206） and General Program of National Natural Science Foundation of China （51674002）.
文摘The emission of dioxins from the iron ore sintering process is the largest emission source of dioxins, and the reduction in dioxin emission from the iron ore sintering process to the environment is increasingly important. Three approaches to control the emission of dioxins were reviewed： source control, process control, and terminal control. Among them, two terminal control technologies, activated carbon adsorption and selective reduction technology, were discussed in detail. Following a comparison of the reduction technologies, the terminal control method was indicated as the key technology to achieve good control of dioxins during the sintering process. For the technical characteristics of the sintering process and flue gas, multiple methods should be collectively considered, and the most suitable method may be addition of inhibitors ＋ ultra-clean dust collection （electrostatic precipitation/bag filter） ＋ desulphurization ＋ selective catalytic reduction to sufficiently remove multiple pollutants, which provides a direction for the cooperative disposal of flue gas pollutants in future.
文摘As the emission control regulations get stricter,the NO;reduction in the sintering process becomes an important environmental concern owing to its role in the formation of photochemical smog and acid rain.The NOxemissions from the sintering machine account for 48% of total amount from the iron and steel industry.Thus,it is essential to reduce NO;emissions from the sintering machine,for the achievement of clean production of sinter.Ca-Fe oxides,serving as the main binding phase in the sinter,are therefore used as additives into the sintering mixture to reduce NOxemissions.The results show that the NO;reduction ratio achieves 27.76% with 8% Ca-Fe oxides additives since the Ca-Fe oxides can advance the ignition and inhibit the nitrogen oxidation compared with the conventional condition.Meanwhile,the existence of Ca-Fe oxides was beneficial to the sinter quality since they were typical low melting point compounds.The optimal mass fraction of Ca-Fe oxides additives should be less than 8%since the permeability of sintering bed was significantly decreased with a further increase of the Ca-Fe oxides fines,inhibiting the mineralization reaction of sintering mixture.Additionally,the appropriate particle size can be obtained when mixing an equal amount of Ca-Fe oxides additives of-0.5 mm and 0.5-3.0 mm in size.
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The authors are grateful for the financial support of the Fundamental Research Funds for the Central Universities(Grant No.FRF-IC-18-010).
文摘Canadian iron concentrate(CIC)can elevate the ferrous grade and lower the contents of gangue components and harmful elements in the sinter.To understand high-temperature characteristics of CIC and typical iron ore,the formation of the melt was calculated mainly through FactSage 7.2,and melt fluidity(MF)test for iron ore fines and penetration characteristic test of CIC melt into iron ore nuclei were carried out via micro-sintering method.The results show that hematite,calcium ferrites,dicalcium silicate,and magnetite take part in the formation of the melt in N2.The formation temperature of the liquid for CIC is higher than that for hematite/limonite ore.The MF of CIC is lower than that of hematite/limonite ore fines.The MF of hematite/limonite ore fines is dominated by the liquid amount and melt viscosity.The penetration depth(PD)of CIC melt into limonite ore nuclei is smaller than that into hematite ore nuclei.The PD is related to the reaction ability of the nuclei with the melt.Based on above results,sinter pot tests were conducted.The result shows that in the base ore blends including two hematite ores and two limonite ores,adding CIC deteriorates the sintering indexes.Increasing the proportion of high-MF and small-PD hematite ore can significantly improve the sintering indexes.10 mass%is a suit-able proportion for adding CIC in ore blends.
基金This work was financially supported by the China Postdoctoral Science Foundation(grant No.2018M640557)the National Natural Science Foundation of China(grant No.51906212)the National Natural Science Foundation of China(grant No.52036008).
文摘The strength properties of green sinter beds,including the Young’s modulus and maximum bed strain,were evaluated using uniaxial compression tests.The green-sinter-bed samples were scanned using X-ray computed tomography(XCT),and the geometry characteristics of the granules were quantified by XCT image analysis.The orthogonal array method was applied to determine the concomitant effects of the moisture,hydrated lime,and concentrate contents on the bed strength characteristics.Less bed strain was observed when the granules had a thin adhering layer and increased interlock contacts,which had a great capacity to resist the applied load collectively.The optimal combination for decreasing the bed maximum strain was 5.8%moisture,2%hydrated lime,and 0%concentrate.The moisture and concentrate contents were the most significant factors determining the green bed strength.Increasing the moisture and concentrate contents produced granules with a thicker and more deformable adhering layer,resulting in a more compact bed.The addition of hydrated lime inhibited rearrangement,deformation,and fracture of the granules in green sinter bed during compression.
基金supported by the State 863 Project(No.2013AA065102,2012AA062501)the National Natural Science Foundation of China(No.21207132)
文摘The activated carbon injection-circulating fluidized bed（ACI-CFB）-bag filter coupling technique was studied in an iron ore sintering plant. For comparison, the removal efficiencies under the conditions without or with ACI technology were both evaluated. It was found that the polychlorinated dibenzo-p-dioxins and dibenzofuran（PCDD/F） removal efficiency for total international toxic equivalence quantity（I-TEQ） concentration was improved from 91.61% to 97.36% when ACI was employed, revealing that ACI was very conducive to further controlling the PCDD/F emissions. Detailed congener distributions of PCDD/Fs in the gas-phase and particle-phase of the Inlet and Outlet samples were determined. Additionally, the PCDD/F distribution for the Fly ash-with ACI sample of was also studied.
基金Item Sponsored by National Natural Science Foundation of China(50974012)National High Technology Research and Development of China(2006AA06Z125)
文摘A model of iron ore sintering was built with consideration of fuel combustion, catalysis of sinter mixture as well as formation of melt and mineral, which was verified via sintering pot tests and showed a good fit to the experi- mental results. The effect of bed depth on temperature was reflected by the residence time in high-temperature zone, rather than the top value of the temperature, which was weakened by melt formation as well as hematite decomposi- tion. Moreover, the effect of bed depth, fuel content and distribution on sintering process was different, which was reflected by temperature profiles and the rule of calcium ferrite formation. The formation of melt as well as magnetite was a process which was decided by kinetic factors, while the formation of calcium ferrite was related to fuel blend- ing conditions, which is determined by thermodynamics when the fuel ratio inside sinter granules is low or fuel con- tent is high, otherwise, it is determined by kinetics.
基金the National Natural Science Foundation of China(52174325)the Key Research and Development Program of Shaanxi(Grant Nos.2020GY-166 and 2020GY-247)the Shaanxi Provincial Innovation Capacity Support Plan(Grant No.2023-CX-TD-53).
文摘The iron oxide(FeO)content had a significant impact on both the metallurgical properties of sintered ores and the economic indicators of the sintering process.Precisely predicting FeO content possessed substantial potential for enhancing the quality of sintered ore and optimizing the sintering process.A multi-model integrated prediction framework for FeO content during the iron ore sintering process was presented.By applying the affinity propagation clustering algorithm,different working conditions were efficiently classified and the support vector machine algorithm was utilized to identify these conditions.Comparison of several models under different working conditions was carried out.The regression prediction model characterized by high precision and robust stability was selected.The model was integrated into the comprehensive multi-model framework.The precision,reliability and credibility of the model were validated through actual production data,yielding an impressive accuracy of 94.57%and a minimal absolute error of 0.13 in FeO content prediction.The real-time prediction of FeO content provided excellent guidance for on-site sinter production.
基金financially supported by the China Postdoctoral Science Foundation (No. 2019M662130)the National Natural Science Foundation of China (No. 51674002)
文摘Resistance in iron ore undergoes a sharp change of up to several orders of magnitude when the sintered solid phase changes to liquid phase.In view of the insufficiency of existing assimilation detection methods,a timing-of-assimilation reaction is proposed,which was judged by continuously detecting the changes in resistance at the reaction interface.Effects of pole position and additional amounts of iron ore on assimilation reaction timing were investigated.The results showed that the suitable depth of pole groove was about 2 mm,and there was no obvious impact when the distance of the poles changed from 4 to 6 mm,or the amount of iron ore changed from 0.4 to 0.6 g.The temperature of sudden change of resistance in the temperature-resistant image was considered to be the lowest assimilation temperature of iron ore.The accuracy of this resistance method was clarified by X-ray diffraction,optical microscope,and scanning electron microscope/energy dispersive spectrometer(SEM/EDS)analyses.
基金supported by National Natural Science Foundation of China(grant No.52036008).
文摘The influence of ammonia and Brown gas injection on the iron ore sintering characteristics was explored through sintering pot experiments based on biochar substitution to increase biochar substitution proportion and reduce fossil energy consumption.By dividing the high-temperature stage of the sintering bed,the heating rate and cooling rate were calculated,and the reasons for poor sintering quality under a high biochar substitution ratio were explored.The results showed that under the 40%biochar substitution ratio,the cooling rate of the sintering bed significantly increased,the high-temperature duration time was short,and the sintering quality deteriorated severely.Additional injection of 0.5–1%vol ammonia or 1–2%vol Brown gas can reduce the cooling rate,prolong the high-temperature duration,and optimize the sintering quality.Based on 1%vol ammonia or 2%vol Brown gas injection,reducing the proportion of biochar with equal calorific value further increases the sintering comprehensive index,which means that using 1%vol ammonia or 2%vol Brown gas injection to assist sintering can reduce the proportion of coke usage to 60%,while the proportion of biochar substitution is 33.76%and 32.47%,respectively.The research results provide an effective solution for low-carbon sintering.
基金financially supported by the Open Research Fund of Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education,Wuhan University of Science and Technology(No.FMRU201405)the National Natural Science Foundation of China(Nos.51471122 and 51604202)the China Postdoctoral Science Foundation(No.2016M592397)
基金Project(2017YFC0210302)supported by the National Key R&D Program of ChinaProjects(U1660206,U1760107)supported by the National Natural Science Foundation of China
文摘Process control is an effective approach to reduce the NOx emission from sintering flue gas.The effects of different materials adhered on coke breeze on NOx emission characteristics and sintering performance were studied.Results showed that the coke breeze adhered with the mixture of CaO and Fe2O3 or calcium ferrite significantly lowers the NOx emission concentration and conversion ratio of fuel-N to NOx.Pretreating the coke with the mixture of lime slurry and iron ore fines helped to improve the granulation effect,and optimize the carbon distribution in granules.When the mass ratio of coke breeze,quick lime,water and iron ore fines was 2:1:1:1,the average NOx emission concentration was decreased from 220 mg/m3 to 166 mg/m3,and the conversion ratio of fuel-N was reduced from 54.2%to 40.9%.
