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Journal of Iron and Steel Research(International) 2020年第7期27卷 770-781页

作者： Feng Zhang De-qing Zhu Jian Pan Zheng-qi Guo Meng-jie Xu School of Minerals Processing and Bioengineering Central South UniversityChangsha 410083HunanChina Sinosteel Equipment&Engineering Co. Ltd.Beijing 100000China

For improving the strength of pellets made of ultrafine and super-high-grade magnetite concentrates,the influence of basicity(CaO/SiO2 ratio)on the roasting and consolidation of pellets was investigated.The results showed that with the basicity of pellets increasing from 0.09 to 0.60,the compressive strength of both preheated and roasted pellets achieved an evident improvement from 502 and 2519 to 549 and 3096 N/pellet,respectively;meanwhile,the roasting time decreased from 15 to 9.min.The low-viscosity liquid phases were easily generated in fired pellets at the basicity range of 0.40-0.60 under the roasting temperature of 1240℃,filled the voids between hematite particles and tightened the bonding among particles,effectively restraining the generation of concentric cracks and decreasing the porosity of fired pellets;low-viscosity liquid phases facilitated the solid diffusion of hematite,leading to the formation of coarse hematite crystals and thicker connecting necks.

关键词： basicity Consolidation Ultrafine and super-high-grade magnetite concentrate Fired pellet Compressive strength Liquid phase

Optimization of PGNAA device and algorithm for testing basicity index of sinter mixture

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Nuclear Science and Techniques 2021年第1期32卷 46-57页

作者： Long Zhao Xu Xu Jing-Bin Lu Ya-Lin Gong Qing-Feng Song Qing-Min Shang Wei Zhang De-You Yin Yan-Feng Li College of Physics Jilin UniversityChangchun 130012China Dandong Dongfang Measurement and Control Technology Co. LtdDandong 118002China

Sinter is the main raw material in the blast furnace iron-making process,and basicity(CaO/SiO2)is an important quality index of sinter.Prompt gamma neutron activation analysis is a multi-elemental online detection technology that has been successfully applied in cement,coal,etc.Compared with cement as a raw material,sinter exhibits poor moderation ability and a large neutron absorption cross section.Therefore,cement detection devices are not suitable for sinter mixture detection.In this study,a prompt gamma neutron activation analysis equipment used for testing cement was re-optimized to render it suitable for measuring a sinter mixture.Using Monte Carlo simulation,the comprehensive detection efficiency of the detection device improved by 71.52%.Because of the gamma-ray self-shielding effect of the sinter mixture,the detection errors of CaO and SiO2 are significant.By applying the gamma-ray self-shielding correction algorithm,the detection accuracies improved,and their linear correlation coefficients R2 exceeded 0.99.Furthermore,by applying an improved analyzer to a sintering plant,the first-grade product rate of the factory increased by 4.64%.

关键词： Prompt gamma neutron activation analysis Sinter basicity Monte Carlo simulation

Effects of ferrosilicon alloy,Si content of steel,and slag basicity on compositions of inclusions during ladle furnace refining of Al-killed steel

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Journal of Iron and Steel Research(International) 2020年第9期27卷 1011-1017页

作者： Jian-fei Xu Kun-peng Wang Ying Wang Zhi-dong Qu Xing-kuang Tu Zenith Steel Group Co. Ltd.Changzhou 213000JiangsuChina

To obtain solid Al2O3 or MgO·Al2O3 inclusions in ladle furnace(LF)refining process and achieve ultra-low total oxygen content in steel through subsequent Ruhrstahl Heraeus degassing,the effects of ferrosilicon alloy,Si content of steel,and slag basicity on the compositions of inclusions during LF refining were investigated in Al-killed steel.Al2O3 inclusions could be transformed into CaO-Al2O3-MgO-CaS inclusions after adding ferrosilicon alloy in the LF refining process as this alloy contains some CaSi alloy impurities.The addition of all ferrosilicon alloys required for the steel in the tapping process could eliminate the influence of Ca in ferrosilicon alloy on the compositions of inclusions.Si in liquid steel had a significant influence on the compositions of inclusions during LF refining when CaO-Al2O3-SiO2-MgO slag with high basicity of 7.0 was used.This was because[Ca]produced by the reaction of CaO and[Al]could be consumed more readily by SiO2 in Si-free steel than in Si-containing steel,which was confirmed by the difference of total calcium content between Si-free and Si-containing steels.As a result,Al2O3 and MgO·Al2O3 inclusions were retained in Si-free steel,whereas calcium aluminate inclusions were found in Si-containing steel.For CaO-Al2O3-SiO2-MgO slag with low basicity of 2.8,Al2O3 and MgO·Al2O3 inclusions were obtained after LF refining in Si-containing steel when all ferrosilicon alloys required for the steel were added in the tapping process.This was because the reaction of CaO and[Al]was weak,and residual[Ca]in the steel could be rapidly consumed by SiO2 in low-basicity slag owing to the low activity of CaO and high activity of SiO2,leading to a low total calcium content of 0.0003%in Si-containing steel.

关键词： Inclusion Ferrosilicon alloy Si content basicity LF refining

Effect of w(MgO)/w(Al_(2)O_(3)) ratio and basicity on microstructure and metallurgical properties of blast furnace slag

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Journal of Iron and Steel Research(International) 2021年第10期28卷 1223-1232页

作者： Wei-guo Kong Ji-hui Liu Yao-wei Yu Xin-mei Hou Zhi-jun He School of Materials and Metallurgy University of Science and Technology LiaoningAnshan114051LiaoningChina State Key Laboratory of Advanced Special Steel Shanghai Key Laboratory of Advanced FerrometallurgySchool of Materials Science and EngineeringShanghai UniversityShanghai200444China

The CaO–SiO_(2)–Al_(2)O_(3)–MgO system is the main component unit in the slag formation process in blast furnace smelting.Its structural changes directly affect the high-temperature metallurgical properties of slag.Molecular dynamics simulations were thus conducted to analyze the microstructure changes of the quaternary slag system under different basicities and w(MgO)/w(Al_(2)O_(3))ratios.The changes in w(MgO)/w(Al_(2)O_(3))ratio and basicity could affect the stability of each ion-oxygen.Increasing the basicity and w(MgO)/w(Al_(2)O_(3))ratio,the average coordination number of O surrounding Si atom only changed a little and remained approximately 4,indicating that Si exists as a stable structure of the[SiO4]4−tetrahedron in the slag structure,while the average coordination number of O surrounding Al atom changed greatly from 4 to 6,which indicated that the Al existence form could be transformed from[AlO_(4)]^(5−) tetrahedron to[AlO_(5)]^(7−) pentahedron and[AlO_(6)]^(9−) octahedron.Also,the diffusion rate of ions was accelerated with the increase in w(MgO)/w(Al_(2)O_(3))ratio and basicity.Moreover,the self-diffusion coefficients of each ion were obtained,and the magnitudes were observed to be in the following order:Mg^(2+)>Ca^(2+)>Al^(3+)>Si^(4+).The calculation and analysis of the slag viscosity and activation energy of viscous flow under different basicities and w(MgO)/w(Al_(2)O_(3))ratios revealed that the metallurgical properties of slag at high temperature depend on the flow-unit diffusivity and the microstructure stability,simultaneously,the basicity should be controlled between 1.0 and 1.2,and the w(MgO)/w(Al_(2)O_(3))ratio could be controlled between 0.45 and 0.55.

关键词： Blast furnace slag Microstructure basicity w(MgO)/w(Al_(2)O_(3))ratio Molecular dynamics

Phosphate enrichment mechanism in CaO–SiO_2–FeO–Fe_2O_3–P_2O_5 steelmaking slags with lower binary basicity

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International Journal of Minerals,Metallurgy and Materials 2016年第5期23卷 520-533页

作者： Jin-yan Li Mei Zhang Min Guo Xue-min Yang State Key Laboratory of Advanced Metallurgy School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083China Key Laboratory of Green Process and Engineering Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China

The addition of silica to steelmaking slags to decrease the binary basicity can promote phosphate enrichment in quenched slag samples. In this study, we experimentally investigated phosphate enrichment behavior in CaO-SiO2-FeO-Fe203-P205 slags with a P205 content of 5.00% and the binary basicity B ranging from 1.0 to 2.0, where the （%Fe/O）/（%CaO） mass percentage ratio was maintained at 0.955. The experimental results are explained by the defined enrichment degree c, of solid solution 2CaO·SiO2-3CaO·P205 （C2S-C3P）, where R_C2S-C3P is a component of the developed ion and molecule coexistence theory （IMCT）-Ni model for calculating the mass action concentrations Ni of structural units in the slags on the basis of the IMCT. The asymmetrically inverse V-shaped relation be- tween phosphate enrichment and binary basicity B was observed to be correlated in the slags under applied two-stage cooling conditions. The maximum content of PROs in the C2S-C3P solid solution reached approximately 30.0% when the binary basicity B was controlled at 1.3.

关键词： phosphates enrichment mechanisms steelmaking slags basicity

Effect of basicity on metallurgical properties of magnesium fluxed pellets

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Journal of Iron and Steel Research(International) 2020年第3期27卷 239-247页

作者： Jie Li Hai-fei An Wei-xing Liu Ai-min Yang Man-sheng Chu College of Metallurgy and Energy North China University of Science and TechnologyTangshan 063000.HebeiChina Hebei Key Laboratory of Data Science and Applications North China University of Science and TechnologyTangshan 063000HebeiChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina

Magnesium fluxed pellets are the focus of blast furnace burden research for reducing environmental load.The pelletizing,roasting and metallurgical properties of a Chinese fine magnetite ore with the addition of magnesium flux were experimentally tested,and the effects of basicity on the consolidation behavior,compressive strength,and reducibility of magnesium fluxed pellets were systematically clarified.Then,the mechanisms were analyzed by means of thermodynamics calculation and scanning electron microscopy-energy-dispersive spectrometry analysis methods.The results show that the consolidation behavior of magnesium fluxed pellets during roasting process was obviously promoted with increasing the basicity of the magnesium fluxed pellets.The compressive strength increased firstly and then decreased,reaching the maximum value of 2352 N/pellet with the basicity of 1.0.The reduction degree increased gradually with enhancing the basicity owing to the fact that the decomposition of the added CaCO^could increase the porosity of pellets,thereby increasing the CO diffusion in pellet during reduction.Simultaneously,the reduction swelling index was improved with increasing the basicity because the generated calcium feirite could effectively suppress the growth of iron whiskers.

关键词： Magnesium fluxed pellet basicity Compressive strength Reduction degree Reduction swelling

Influence of basicity on metallurgical performances of fired super high-grade magnetite pellets in hydrogen-rich gases

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Journal of Iron and Steel Research(International) 2021年第10期28卷 1212-1222页

作者： Feng Zhang De-qing Zhu Jian Pan Zheng-qi Guo Meng-jie Xu College of Materials and Metallurgy Guizhou UniversityGuiyang550025GuizhouChina School of Minerals Processing and Bioengineering Central South UniversityChangsha410083HunanChina Sinosteel Equipment&Engineering Co. Ltd.Beijing100080China

The influence of basicity on the metallurgical performances and reduction characteristics of fired super high-grade magnetite pellets under the simulated shaft furnace gas conditions was investigated.The fired pellets in the basicity range of 0.09(natural basicity)to 1.00 show superior reducibility and low-temperature disintegration performance.However,in the basicity range of 0.20–0.80,the abnormal swelling of the fired pellets occurs.Improving basicity from 0.09 to 0.40 promotes the generation of low melting point slag phases and lower porosity of fired pellets,and accelerates the growth and densification of hematite crystals,impeding the reduction of hematite particles and the formation of metallic iron shell.In addition,the slags that distribute between the hematite particles absorb the reduction stresses by increased distances between the particles during the reduction process,which leads to the large reduction swelling of pellets.

关键词： Ultrafine high-grade magnetite concentrate basicity Metallurgical performance Reduction behavior Gas-based shaft furnace direct reduction Fired pellet

Desulfurization ability of refining slag with medium basicity

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International Journal of Minerals,Metallurgy and Materials 2014年第12期21卷 1160-1166页

作者： Hui-xiang Yu Xin-hua Wang Mao Wang Wan-jun Wang State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

The desulfurization ability of refining slag with relative lower basicity （B） and Al2O3 content （B = 3.5-5.0; 20wt%-25wt% Al2O3） was studied. Firstly, the component activities and sulfide capacity （Cs） of the slag were calculated. Then slag-metal equilibrium experiments were carried out to measure the equilibrium sulfur distribution （Ls）. Based on the laboratorial experiments, slag composition was optimized for a better desulfurization ability, which was verified by industrial trials in a steel plant. The obtained results indicated that an MgO-saturated CaO-Al2O3-SiO2-MgO system with the basicity of about 3.5-5.0 and the Al2O3 content in the range of 20wt%-25wt% has high activity of CaO （αCaO）, with no deterioration of Cs compared with conventional desulfurization slag. The measured Ls between high-strength low-alloyed （HSLA） steel and slag with a basicity of about 3.5 and an Al2O3 content of about 20wt% and between HSLA steel and slag with a basicity of about 5.0 and an Al2O3 content of about 25wt% is 350 and 275, respectively. The new slag with a basicity of about 3.5-5.0 and an Al2O3 content of about 20wt% has strong desulfurization ability. In particular, the key for high-efficiency desulfurization is to keep oxygen potential in the reaction system as low as possible, which was also verified by industrial trials.

关键词： high-strength steel low alloyed steel refining slag basicity desulfurization thermodynamic calculations

Effect of basicity and Al2O3 on viscosity of ferronickel smelting slag

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Journal of Iron and Steel Research(International) 2020年第12期27卷 1400-1406页

作者： Yong-feng Chen Xue-ming Lv Zheng-de Pang Xue-wei Lv Wuhu Xinxing Ductile Iron Pipes Co. Ltd.Wuhu 241000AnhuiChina Pangang Group Research Institute Co. Ltd.Panzhihua 617000SichuanChina Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials Chongqing UniversityChongqing 400044China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China

The effect of the Al2O3 content and basicity (the molar ratio of MgO to SiO2) on the viscosity of a SiO2-MgO-FeOAl2O3-CaO slag was studied to fully understand the smelting process of the ferronickel alloy. Experimental results show that the slag is a mixture of liquid and solid phases at the experimental temperature. The viscosity decreased as the basicity increased and increased as the Al2O3 content increased. To determine the effect of the Al2O3 content and basicity on the structure of the molten slag, Raman spectroscopy was performed on the slag sample, which was quenched from the high temperature with water. The Raman spectra showed that the fractions of the polymerization structural units decreased significantly as the basicity of the slag increased, resulting in a decrease in the apparent viscosity. However, Al2O3 acts as a network former in the slag system, thereby making the slag structure further polymerized and increasing the viscosity.

关键词： Nickel laterite ore Slag structure Viscosity basicity Ferronickel smelting slag

Behavior of phosphorus enrichment in dephosphorization slag at low temperature and low basicity

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International Journal of Minerals,Metallurgy and Materials 2021年第1期28卷 66-75页

作者： Ge-fan Ye Jian Yang Run-hao Zhang Wen-kui Yang Han Sun State Key Laboratory of Advanced Special Steel School of Materials Science and EngineeringShanghai UniversityShanghai 200444China

At low basicity and low temperature, the dephosphorization behavior and phosphorus distribution ratio(LP) between slag and molten steel in the double slag and remaining slag process were studied with a 180 t basic oxygen furnace industrial experiment.The dephosphorization slags with different basicities were quantitatively analyzed.At the lower basicity range of 0.9–2.59, both LP and dephosphorization ratio were increased as the basicity of dephosphorization slag increased.Dephosphorization slag consisted of dark gray P-rich, light gray liquid slag,and white Fe-rich phases.With increasing basicity, not only did the morphologies of different phases in the dephosphorization slag change greatly, but the area fractions and P2O5 content of the P-rich phase also increased.The transfer route of P during dephosphorization can be deduced as hot metal → liquid slag phase + Fe-rich phase → P-rich phase.

关键词： dephosphorization basicity phosphorus-rich phase slag converter steelmaking