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Reduction Behaviors of Pellets Under Different Reducing Potentials

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Journal of Iron and Steel Research International 2013年第12期20卷 12-18页

作者： ZUO Xiao-jian WANG Jing-song AN Xiu-wei SHE xue-feng xue qing-guo State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing

Owing to the change of gas composition in top gas recycling-oxygen blast furnaces compared with tradi- tional blast furnace, many attentions are attracted to the research on iron oxide reduction again. In order to study the influence of H2 and CO on the reduction behavior of pellets, experiments were conducted with H2-N2, CO N2 or H2-CO gas mixtures at 1 173 K by measuring the mass loss, respectively. It was found that the reduction degree in creased with increasing the ratio of H2 or CO in the gas mixture, but the reduction with hydrogen was faster than that with carbon monoxide. The reduction degree could reach 96. 720/00 after 65 rain for the reduction with 50~ H2 ＋ 50% N2, while it is only 53.37~ for the reduction with 50~ COq-50~ N2. The addition of hydrogen to carbon monoxide will accelerate the reduction because the hydrogen molecules are more easily chemisorbed and reacted with iron oxide than carbon monoxide. A scanning electron microscope was used to characterize the structures of reduced samples. Dense structure of iron was obtained in the reduction with hydrogen while the structure of iron showed many small fragments for the reduction with carbon monoxide. At the later stage of reduction with the gas mixtures containing carbon monoxide, the reduction curves showed a descending trend because the rate of carbon deposition caused by the thermal decomposition of carbon monoxide was faster than the rate of oxygen loss. Compared with the reduction with CO-N2 and H2 CO gas mixtures, H2 gas could enhance the carbon deposition while N2 gas would re- duce this phenomenon. The results of X-ray diffraction and chemical analysis demonstrated that the carbons are mainly in the form of cementite （FeaC） and graphite in reduced sample.

关键词： reduction pellet hydrogen carbon monoxide carbon deposition

Reduction Characteristics and Kinetics of Bayanobo Complex Iron Ore Carbon Bearing Pellets

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Journal of Iron and Steel Research International 2013年第5期20卷 28-33页

作者： DING Yin-gui WANG Jing-song SHE xue-feng WANG Guang xue qing-guo State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing

The kinetics of isothermal reduction of the carbon bearing pellets, which were mainly composed of Bayanobo complex iron ore and pulverized coal, was investigated by thermogravimetry at the temperature of 1 273-1 673 K. The effects of xC/xO and the atmospheres on the extent of reduction also were investigated. The results indicate that the fractional reaction increased proportionally with temperature increasing and heating temperature is the significant influence factor to the reaction of carbon bearing pellets. The optimum xC/xO is 1.2 and the effect of atmosphere on the reduction of iron oxides is almost negligible. The results can be interpreted that the reaction was initially controlled by a mixed controlled mechanism of carbon gasification and interface chemical reaction, and in the later stage, interface chemical reaction became the rate-controlling step. Apparent activation energy values of reduction at different levels of fractional reaction were calculated. Before F （fraction of reaction）=0.5, the apparent activation energy ranges from 66.39 to 75.64 kJ/mol, while after F=0.5, the apparent activation energy is 80.98 to 85.37 kJ/mol.

关键词： Bayanobo complex iron ore carbon bearing pellet thermogravimetry apparent activation energy

Softening and Melting Behavior of Mixed Burden for Oxygen Blast Furnace

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Journal of Iron and Steel Research International 2013年第5期20卷 11-16页

作者： AN Xiu-wei WANG Jing-song LAN Rong-zong HAN Yi-hua xue qing-guo State Key Laboratory of Advanced Metallurgy School of Metallurgical and Ecological Engineering University of Science and Technology Beijing

The behaviors of mixed burden in the cohesive zone of oxygen blast furnace were studied by softening and melting tests, and the influence of reducing gas and burden basicity on the softening and melting behaviors of mixed burden was also investigated. The results indicated that the softening range became wide, however, the melting range narrowed sharply in the atmosphere of oxygen blast furnace. The permeability of burden in the oxygen blast furnace was obviously improved comparing with the conventional blast furnace. In addition, the content of sulphur in the dripping iron of oxygen blast furnace was much lower than that of conventional blast furnace, however, the content of carbon increased. An optimum basicity of burden, which could lead to the appearance of the narrower melting range and better permeability of burden, was obtained in the atmosphere of oxygen blast furnace.

关键词： oxygen blast furnace softening melting mixed burden basicity reduction degree

Comprehensive Utilization of Paigeite Ore Using Iron Nugget Making Process

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Journal of Iron and Steel Research International 2012年第6期19卷 9-13页

作者： DING Yin-gui WANG Jing-song WANG Guang MA Sai xue qing-guo State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

The feasibility of paigeite ore treatment with iron nugget making process is proved. The isothermal reduc- tion experiments at laboratory scale were carried out, using carbon bearing pellets which were made of boron contai- ning iron concentrate and pulverized coal mainly, from 1 623 to 1 723 K with different heating time. The results indi- cated that iron nugget making process depends mainly on heating time and temperature. And the iron nugget and slag can separate in a clean manner at 1 673 K for 15 min. For the iron nugget, the C content is 3.57% （mass percent） and B is 0. 065~ （mass percent）. The B203 content of slag is 20.01~/00, and the boron was concentrated into one phase which is identified as suanite （Mg2BaOs） during the solidification. With an extraction ratio of 80~ under the atmospheric conditions, the activity of boron in slag is good. The boron-rich slag can be used to extract boric or boric acid and alleviate the shortage of boron resource. Through series of calculation and analysis related, it can be conclu- ded that the recovery ratio of Fe and boron are about 98% and 97% respectively. The results show that this method is feasible and effective on the utilization of paigeite ore.

关键词： boron containing iron concentrate carbon bearing pellets iron nugget boron-rich slag

Effect of slag composition on kinetic behavior of deep deoxidation of 5 wt.% Si high-silicon austenitic stainless steel

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Journal of Iron and Steel Research International 2024年第8期31卷 1873-1885页

作者： Guan-xiong Dou Han-jie guo Jing guo xue-cheng Peng qing-yun Chen School of Metallurgical and Ecological Engineering University of Science and Technology Beijing(USTB)Beijing 100083China Beijing Key Laboratory of Special Melting and Preparation of High-End Metal Materials Beijing 100083China

Based on a thermodynamic study of 5 wt.%Si high-silicon austenitic stainless steel(SS-5Si)smelting using CaF_(2)-CaO-Al_(2)0_(3)-Mg-Si0_(2) slag to obtain a low oxygen content of less than 10×10^(-4) wt.%,a kinetic mass transfer model for deep deoxidation was established through laboratory studies,and the effects of slag components and temperature on deoxidation during the slag-steel reaction process of sS-5Si were systematically *** experimental data verified the accuracy of the model *** results showed that the final oxygen content in the steel at 1873 K was mainly controlled by the oxygen content derived from the activity of SiO_(2) regulated by the[Si]-[O]equilibrium reaction in the slag system;in particular,when the slag basicity R(R=w(CaO)/w(SiO2),where w(CaO)and w(SiO_(2))are the contents of CaO and SiO_(2) in the slag,respectively)is 3,the Al2O3 content in the slag needs to be less than 2.7%.The mass transfer rate equation for the kinetics of the deoxidation reaction revealed that the mass transfer of oxygen in the liquid metal is the rate-controlling step under different slag conditions at 1873 K,and the oxygen transfer coefficient ko.m increases with increasing the slag basicity from 4.0×10^(-6)m s^(-1)(R=1)to 4.3×10^(-5) m s^(-1)(R=3).ko.m values at R=2 and R=3 are almost the same,indicating that high slag basicity has little *** integral of the mass transfer rate equation for the deoxidation reaction of SS-5Si under different slag conditions is *** total oxygen content of the molten steel decreases with increasing basicity from an initial content of 22×10^(-4) to 3.2×10^(-4) wt.%(R=3),consistent with the change in ko.m with slag *** R=2,the slag-steel reaction takes 15 min to reach equilibrium(w[O]=5.5×10^(-4) wt.%),whereas at R=3,the slag-steel reaction takes 30 min to reach equilibrium(w[0]=3.2×10^(-4) wt.%).Considering the depth of deoxidation and reaction time of SS-5Si smelting,it is recommended the slag b

关键词： Slag-steel reaction Kinetics Rate-controlling step Deep deoxidation Transfer coefficient

Exploring a new path of green and efficient utilization of sinter return fine to produce composite pellets

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Journal of Iron and Steel Research International 2024年第7期31卷 1610-1622页

作者： Yan-biao Chen Wen-guo Liu Hao guo Jing-song Wang qing-guo xue Hai-bin Zuo State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China MCC Capital Engineering and Research Incorporation Limited Beijing 100176China

Efficient utilization of sinter return fine is an important measure to reduce cost,increase efficiency,save energy and reduce emission.A new path of green and efficient utilization of return fine was proposed to produce composite *** metallurgical properties of composite pellets under the condition of hydrogen-rich blast furnace were *** experimental results indicate that the coated concentrate was consolidated for the composite pellets through normal Fe_(2)O_(3) *** the surface of core return fine,the liquid phase formed due to its low-melting point,assimilated the adjacent concentrate,and then consolidated with the temperature *** with regular pellets,the com-pressive strength and reduction swelling index of composite pellets were decreased,but the reducibility index and softening-melting properties were *** addition,the reduction degradation index of composite pellets was sig-nificantly higher than that of ***,adding composite pellets was conducive to indirect reduction in blast furnace,reducing fuel ratio and improving production *** to the effect of the roasting system on the metallurgical properties,the roasting temperature and time were determined as 1250℃and 30 min,*** composite pellets can be produced under the traditional pelletizing process.

关键词： Sinter Return fine Composite pellet Roasting system Metallurgical property Hydrogen-rich blast furnace

The molecular genetics of PI3K/PTEN/AKT/mTOR pathway in the malformations of cortical development

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Genes & Diseases 2024年第5期11卷 252-271页

作者： qing Ma Guang Chen Ying Li Zhenming guo xue Zhang NHC and CAMS Key Laboratory of Molecular Probe and Targeted Theranostics Harbin Medical UniversityHarbinHeilongjiang 150000China Department of Urology The Fourth Hospital of Harbin Medical UniversityHarbinHeilongjiang 150000China Department of Child and Adolescent Health School of Public HealthHarbin Medical UniversityHarbinHeilongjiang 150000China Institute for Regenerative Medicine Shanghai East HospitalFrontier Science Center for Stem Cell ResearchSchool of Life Sciences and TechnologyTongji UniversityShanghai 200120China

Malformations of cortical development(MCD)are a group of developmental disorders characterized by abnormal cortical structures caused by genetic or harmful environmental *** kinds of MCD are caused by genetic *** is the common cause of intellectual disability and intractable *** rapid advances in imaging and sequencing technologies,the diagnostic rate of MCD has been increasing,and many potential genes causing MCD have been successively ***,the high genetic heterogeneity of MCD makes it challenging to understand the molecular pathogenesis of MCD and to identify effective targeted ***,in this review,we outline important events of cortical *** we illustrate the progress of molecular genetic studies about MCD focusing on the PI3K/PTEN/AKT/mTOR ***,we briefly discuss the diagnostic methods,disease models,and therapeutic strategies for *** information will facilitate further research on *** the role of the PI3K/PTEN/AKT/mTOR pathway in MCD could lead to a novel strategy for treating MCD-related diseases.

关键词： Epilepsy Gene mutation Genetics Malformations of cortical development PI3K/PTEN/AKT/mTOR pathway

Improving mathematical model of burden distribution and correcting chute angle to cope with fluctuation of stock line

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Journal of Iron and Steel Research International 2024年第2期31卷 342-356页

作者： Jian-sheng Chen Wen-guo Liu Hao guo Wang Ding qing-guo xue Jing-song Wang Hai-bin Zuo State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing100083China MCC Capital Engineering&Research Incorporation Limited Beijing100176China Hunan Valin Xiangtan Iron and Steel Co. Ltd.Xiangtan411101HunanChina

Accurate evaluations of the burden distribution are of critical importance to stabilize the operation of blast *** mathematical model and discrete element method(DEM)are two attractive methods for predicting burden *** on DEM,the initial velocities of the pellet,sinter,and coke were calculated,and the velocity attenuations of the above three particles between the burden and the chute were *** initial velocity and velocity attenuation were applied to a mathematical model for improving the ***,based on the improved model,a scheme for rectifying the chute angles was proposed to address the fluctuation of the stock line and maintain a stable burden *** validity of the scheme was confirmed via a stable burden distribution under different stock *** mathematical model has been successfully applied to evaluate the online burden distribution and cope with the fluctuation of the stock line.

关键词： Burden distribution Mathematical model Discrete element method Velocity attenuation Stock line fluctuation

The impact of climate change on forest fire danger rating in China’s boreal forest

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Journal of Forestry Research 2011年第2期22卷 249-257页

作者： YANG Guang DI xue-ying guo qing-xi SHU Zhan ZENG Tao YU Hong-zhou WANG Chao College of Forestry Northeast Forestry University Harbin 150040 P.R.China.

The Great Xing＇an Mountains boreal forests were focused on in the northeastern *** simulated future climate scenarios of IPCC SRES A2a and B2a for both the baseline period of 1961-1990 and the future scenario periods were downscaled by the Delta Method and the Weather Generator to produce daily weather *** the verification with local weather and fire data,the Canadian Forest Fire Weather Index System was used to assess the forest fire weather situation under climate change in the study *** increasing trend of fire weather severity was found over the 21st century in the study region under the both future climate change scenarios,compared to the 1961-1990 baseline *** annual mean/maximum fire weather index was predicted to rise continuously during 2010-2099,and by the end of the 21st century it is predicted to rise by 22%-52% across much of China＇s boreal *** significant increases were predicted in the spring from of April to June and in the summer from July to *** the summer,the fire weather index was predicted to be higher than the current index by as much as 148% by the end of the 21st *** the scenarios of SRES A2a and B2a,both the chance of extremely high fire danger occurrence and the number of days of extremely high fire danger occurrence was predicted to increase in the study *** is anticipated that the number of extremely high fire danger days would increase from 44 days in 1980s to 53-75 days by the end of the 21st century.

关键词： climate change wildfire boreal forest fire weather species West Africa