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Effect of Al_(2)O_(3)/SiO_(2) mass ratio and CaO content on viscosity and structure of slag for pyrometallurgical processing of spent automotive catalysts

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Journal of Iron and Steel Research(International) 2024年第3期31卷 608-621页

作者： Zhe Wang Qi-long Wei Cheng-bin Shi Zhan-cheng Guo State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

The effect of Al_(2)O_(3)/SiO_(2) mass ratio and CaO content on the viscosity and structure of the CaO-Al_(2)O_(3)-SiO_(2)-6MgO-1.5ZrO_(2)-1.5CeO_(2) slag was investigated.The results show that with the increase in Al_(2)O_(3)/SiO_(2) mass ratio,the viscous flow units within the slag gradually change from Si-O-Si to Al-O-Al and Al-O-Si.Furthermore,the substitution of Al_(2)O_(3) for SiO_(2) leads to the transformation of Si-O bonds towards weaker Al-O bonds,which weaken the bond strength of the aluminosilicate networks,thus leading to a decrease in the viscosity of slag.The increase in CaO content effectively promotes the depolymerization of the aluminosilicate networks,resulting in a significant decrease in the viscosity of the slag.The slag with Al_(2)O_(3)/SiO_(2) of 0.7-1.5 and CaO of 30 wt.%shows promise as the reference slag system for the Fe-collection smelting of spent automotive catalysts due to its good comprehensive performance.

关键词： Aluminosilicate slag Al_(2)O_(3)/SiO_(2)mass ratio CaO content Viscosity Slag structure

New steelmaking process based on clean deoxidation technology

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International Journal of Minerals,metallurgy and Materials 2024年第6期31卷 1249-1262页

作者： Zhongliang Wang Yanping Bao State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

After the converter steelmaking process,a considerable number of ferroalloys are needed to remove dissolved oxygen from the molten steel,but it also forms a lot of oxide inclusions that cannot be completely removed.At the same time,it increases the carbon emis-sions in the steel production process.After years of research,our team have developed a series of clean deoxidation technologies,includ-ing carbon deoxidation,hydrogen deoxidation,and waste plastic deoxidation of molten steel to address the aforementioned issues.In this study,thermodynamic calculations and laboratory experiments were employed to verify that carbon and hydrogen can reduce the total oxygen content in the molten steel melt to below 5×10^(-6) and 10×10^(-6),respectively.An analysis of the deoxidation mechanisms and ef-fects of polyethylene and polypropylene was also conducted.In addition,the applications of carbon deoxidation technology in different steels with the hot-state experiment and industrial production were discussed carefully.The carbon deoxidation experimental results of different steels were as follows:(1)the oxygen content of bearing steel was effectively controlled at 6.3×10^(-6) and the inclusion number density was lowered by 74.73%compared to aluminum deoxidized bearing steel;(2)the oxygen content in gear steel was reduced to 7.7×10^(-6) and a 54.49%reduction of inclusion number density was achieved with almost no inclusions larger than 5μm from the average level of industry gear steels;(3)a total oxygen content of M2 high-speed steel was as low as 3.7×10^(-6).In industrial production practice,car-bon deoxidation technique was applied in the final deoxidation stage for non-aluminum deoxidized bearing steel,and it yielded excellent results that the oxygen content was reduced to below 8×10^(-6) and the oxide inclusions in the steel mainly consist of silicates,along with small amounts of spinel and calcium aluminate.

关键词： clean deoxidation carbon deoxidation hydrogen deoxidation waste plastics deoxidation

Development and prospects of molten steel deoxidation in steelmaking process

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International Journal of Minerals,metallurgy and Materials 2024年第1期31卷 18-32页

作者： Zhongliang Wang Yanping Bao State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

In the long traditional process of steelmaking,excess oxygen is blown into the converter,and alloying elements are used for deoxidation.This inevitably results in excessive deoxidation of products remaining within the steel liquid,affecting the cleanliness of the steel.With the increasing requirements for steel performance,reducing the oxygen content in the steel liquid and ensuring its high cleanliness is necessary.After more than a hundred years of development,the total oxygen content in steel has been reduced from approximately 100×10^(-6)to approximately 10×10^(-6),and it can be controlled below 5×10^(-6)in some steel grades.A relatively stable and mature deoxidation technology has been formed,but further reducing the oxygen content in steel is no longer significant for improving steel quality.Our research team developed a deoxidation technology for bearing steel by optimizing the entire conventional process.The technology combines silicon–manganese predeoxidation,ladle furnace diffusion deoxidation,and vacuum final deoxidation.We successfully conducted industrial experiments and produced interstitial-free steel with natural decarbonization predeoxidation.Non-aluminum deoxidation was found to control the oxygen content in bearing steel to between 4×10^(-6) and 8×10^(-6),altering the type of inclusions,eliminating large particle Ds-type inclusions,improving the flowability of the steel liquid,and deriving a higher fatigue life.The natural decarbonization predeoxidation of interstitial-free steel reduced aluminum consumption and production costs and significantly improved the quality of cast billets.

关键词： steel deoxidation deoxidizer metallurgical equipment bearing steel IF steel

Preparation of gangue ceramsite by sintering pot test and potential analysis of waste heat recovery from flue gas

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Journal of Iron and Steel Research(International) 2023年第7期30卷 1401-1410页

作者： Yi Huang Xiang-jie Duan Yu Li Wei Zhang State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

Preparation of ceramsite from solid waste based on the sintering process is a new technology and had a high efficiency in improving producing capability, decreasing consumption of liquefied petroleum gas (LPG), and recovering waste heat of flue gas. An experiment sintering gangue ceramsite was conducted in a 25 kg scale sintering pot with a 100 cm height. The combustion characteristics, phase transformation, and the release profile of SO_(2)^(*) (SO and/or SO_(2)) and NO_(x)^(*) (N_(2)O, NO, and/or NO_(2)) of gangue ceramsite during the sintering process were studied by X-ray diffraction analysis, X-ray fluorescence spectrometry, thermogravimetry–differential thermogravimetry–differential scanning calorimetry, and measurement of physical properties of ceramsite and gas components of flue gas. The results showed that the gangue ceramsite had excellent properties, and its compressive strength and water absorption were 8.2–9.6 MPa and 8.9%–9.8%, respectively, far exceeding the requirement of standard (GB/T 17431.1–2010). The ignition temperature of gangue ceramsite was 443 ℃, and the ignition loss was 14.60 mass% at 1000 ℃. Kaolinite and calcite disappeared at 600 and 800 ℃, respectively. Albite disappeared and mullite formed at 1000 ℃. Two peaks of SO_(2)^(*) emissions emerged in the range of 311–346 mg m^(-3) near 500 ℃ of upper layer ceramsite and 420–489 mg m^(-3) near 1000 ℃ of lower layer ceramsite, respectively. NO_(x)^(*) emissions peak emerged in the range of 227–258 mg m^(-3) near 550 ℃ of the upper layer ceramsite, which was related to the oxidation of sulfide and the combustion of LPG. Gangue is a direct heat source for sintering of ceramsite as well. During sintering process, the heat of flue gas above and below 400 ℃ accounts for 55.9% and 30.0% of the all-output heat, respectively, and was potentially used for producing waste-heat steam or electricity as by-products and drying raw materials during its own initial sintering process, which can realize combined mass and heat utilization for the gangue an

关键词： Gangue ceramsite Cogeneration SO_(2)^(*) NO_(x)^(*) Flue gas waste heat

Mathematical model of burden distribution in bell-less top blast furnace

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Journal of Iron and Steel Research(International) 2023年第2期30卷 216-226页

作者： Jian-sheng Chen Hai-bin Zuo Jing-xiu Wang Qing-guo Xue Jing-song Wang State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing100083China

The burden distribution in the shaft of blast furnace is known to affect the gas distribution,heat transfer,and chemical reactions inside the furnace.However,the internal layer structure of burden in the shaft cannot be directly measured.Hence,a mathematical model for evaluating burden profile and layer structure was established.A sensitivity analysis based on the model was implemented to elucidate the effect of some factors on the burden distribution,including the stockline height and the mass of central coke.The results show that the width of funnel zone widens with the increase in stockline height,and the mass percentage of ore to coke in this zone slightly increases.Besides,the mass of central coke shows a significant influence on the width of coke channel,and 2%of batch mass of coke is recommended to implement central coke charging operation.The model has been indirectly verified by the gas temperature in operating blast furnace and successfully applied to online evaluate burden distribution.

关键词： Blast furnace Burden distribution Mathematical model Stockline height Central coke

Formation and evolution of primary carbides in high-carbon martensitic stainless steel

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Journal of Iron and Steel Research(International) 2023年第10期30卷 2000-2009页

作者： Chang Sun Jing Li Jie Zhang Wei Yan Shou-hui Li State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

The micro structure of 10Cr15MoVCo electroslag remelting(ESR)ingot was observed using an optical microscope and a scanning electron microscope.There are differences in the number,size,and distribution of primary carbides in different positions of ESR ingot.The results show that the two-dimensional morphology of primary carbides is blocky,fibrous,and spherulitic.The three-dimensional morphology of primary carbides is blocky,spherulitic,fibrous,and short rods.X-ray diffraction results show that primary carbides are M_(7)C_(3) carbides.Electron backscattered diffraction results indicate that large-sized primary carbides consist of blocky,fibrous,and spherulitic carbides with different orientations.High-tem-perature diffusion annealing experiments show that as the temperature increases,the continuity between primary carbides decreases,and the precipitated secondary carbides disappear.The area fraction of primary carbides is reduced,but the morphology of primary carbide is unchanged.The effect of high-temperature diffusion annealing on the dissolution of M_(7)C_(3) primary carbon compounds in ESR ingot was limited.

关键词： M_(7)C_(3)primary carbide Morphology High-temperature diffusion annealing Martensitic stainless steel Evolution

Effects of ZnO,FeO and Fe_(2)O_(3)on the spinel formation,microstructure and physicochemical properties of augite-based glass ceramics

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International Journal of Minerals,metallurgy and Materials 2023年第6期30卷 1207-1216页

作者： Shuai Zhang Yanling Zhang Shaowen Wu State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

Augite-based glass ceramics were synthesised using ZnO,FeO,and Fe_(2)O_(3)as additives,and the spinel formation,matrix structure,crystallisation thermodynamics,and physicochemical properties were investigated.The results showed that oxides resulted in numerous preliminary spinels in the glass matrix.FeO,ZnO,and Fe_(2)O_(3)influenced the formation of spinel,while FeO simplified the glass network.FeO and ZnO promoted bulk crystallisation of the parent glass.After adding oxides,the grains of augite phase were refined,and the relative quantities of augite crystal planes were also influenced.All samples displayed good mechanical properties and chemical stability.The 2wt%ZnO-doping sample displayed the maximum flexural strength(170.3 MPa).Chromium leaching amount values of all the samples were less than the national standard(1.5 mg/L),confirming the safety of the materials.In conclusion,an appropriate amount of zinc-containing raw material is beneficial for the preparation of augite-based glass ceramics.

关键词： spinel network structure thermodynamics microstructure glass ceramics

Single-atom electrocatalyst and gel polymer electrolyte boost the energy density and life of aluminum-sulfur batteries

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Journal of Materials Science & Technology 2023年第21期152卷 86-93页

作者： Zheng Huang Wei Wang Mingyin Kou Haiping Lei Yiwa Luo Shuqiang Jiao State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

Aluminum-sulfur(Al-S)batteries are regarded as a desirable candidate for large-scale energy storage be-cause of their high energy density and abundant natural resources of electrode materials.To address the critical issues of low discharge voltage and rapid capacity decay in Al-S batteries,here an electrocatalyst-assisted gel-polymer electrolyte(GPE)-based Al-S battery is fabricated using platinum nanoparticles deco-rated platinum/nitrogen co-doped graphene(PtNG)as sulfur host for positive electrode and metal-organic frameworks(MOF)filled GPE(MOF@GPE)as solid electrolyte.Pt-based active sites derived from Pt nan-oclusters’surface and atomically dispersed Pt-N_(2) chemical bonds in PtNG can catalyze the decomposition of sulfur and polysulfides in the electrochemical process,greatly accelerating the sulfur redox kinetics.Furthermore,the MOF fillers in MOF@GPE electrolyte significantly inhibit the shuttle effect of polysul-fides,efficiently improving the utilization of sulfur.Consequently,the established Al-S battery delivers a specific capacity of 1009 mAh g^(−1) with a discharge plateau of∼0.95 V,along with a capacity retention of 65% after 300 cycles,revealing ultrahigh energy density and long cycle life.Such a strategy of combin-ing electrocatalyst and MOF-based gel electrolyte affords a fresh plateau for promoting the rechargeable ability of Al-S batteries,advancing remarkable routes for achieving efficient and stable energy storage devices.

关键词： Aluminum-sulfur batteries Gel polymer electrolyte Single atom electrocatalyst Shuttle effect Reaction kinetics

Softening and melting behaviors of ferrous burden in hydrogen-rich blast furnace cohesive zone

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Journal of Iron and Steel Research(International) 2023年第12期30卷 2366-2377页

作者： Bin-bin Lyu Guang Wang Fan Yang Hai-bin Zuo Qing-guo Xue Jing-song Wang State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing100083China

The changes in the softening and melting behaviors of ferrous burden in the cohesive zone and the characteristics of the slag–iron–coke interface in a blast furnace were investigated by simulating an actual blast furnace under hydrogen-rich conditions.According to the variation in the transient shrinkage of the burden under different atmospheres,the shrinkage start temperature of the sinter was higher than that of the pellets.The negative shrinkage rate of the pellets was greater than that of the sinter.Additionally,the softening start temperature in the blast furnace decreased under hydrogen-rich conditions,giving the blast furnace a broader range of softening zones.The softening start temperatures of the pellets and sinter decreased from 1102 to 949℃ and 1152 to 1080℃,respectively.The hydrogen-rich traditional blast furnace conditions narrowed the melting zone temperature range and shifted it toward the high-temperature zone,significantly improving the burden layer permeability.However,under the hydrogen-rich oxygen blast furnace conditions,there were a decrease in the melting start temperature,a shift of the melting zone location to the low-temperature zone,and an increase in the burden layer permeability and pressure difference.A comparison of the slag–iron–coke interface characteristics under different atmospheric conditions showed that the carbon content in metallic iron decreased under hydrogen-rich traditional blast furnace conditions compared with traditional blast furnace conditions.Contrastingly,under hydrogen-rich oxygen blast furnace conditions,the carbon content in metallic iron increased compared with oxygen blast furnace conditions.These findings provide guidance for the development of low-carbon ironmaking processes in blast furnaces.

关键词： Ferrous burden-Hydrogen Softening Melting Cohesive zone Slag-iron-coke interface