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Modelling Effect of Circulation Flow Rate on Inclusion Removal in RH Degasser

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Journal of Iron and Steel Research International 2016年第12期23卷 1243-1248页

作者： shu-guo zheng miao-yong zhu School of Metallurgy Northeastern University

Based on the similarity principles, a 1 ： 7 scale physical model was established to study the behavior of molten steel flow and inclusion removal in a 145 t Rheinsahl-Heraeus （RH） degasser. On the basis of the quantitative measurements of the circulation flow rate and inclusion removal under various lifting gas flow rates, the effect of circulation flow rate on inclusion removal was investigated in the RH degasser. The inclusion removal rate shows the trend of first increase and then decrease twice with increasing the circulation flow rate when the circulation flow rates are smaller than 104.7 L/min. Whereas, the inclusion removal rate increases again with the further increase in circu- lation flow rate when the circulation flow rate is larger than 104.7 L/min. At lower circulation flow rates, inclusions are mainly removed by Stokes flotation to the slag/steel interface after inclusions are transferred near the slag/steel interface by the circulation flow. At higher circulation flow rates, the collision and aggregation of inclusions improves the inclusion removal efficiency. With the further increase in the circulation flow rate, inclusions are mainly removed by following the turbulent fluctuation （turbulent diffusion） to the slag/steel interface after inclusions are transferred near the slag/steel interface by the circulation flow.

关键词： RH degasser lifting gas flow rate circulation flow rate inclusion removal physical modelling

Optimization of flow control devices in a tenstrand billet caster tundish

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China Foundry 2016年第6期13卷 414-421页

作者： shu-guo zheng miao-yong zhu School of Metallurgy Northeastern University

The physical model of a ten-strand billet caster tundish was established to study the effects of various flow control devices on the melt flow. Before and after the optimization of the melt flow, the inclusion removal in the tundish was evaluated by plant trials. The physical modeling results show that when combined with a baffle, the turbulence inhibitor, instead of the impact pad, can significantly improve the melt flow. A turbulence inhibitor with a longer length of inner cavity and without an extending lip at the top of the sidewall seems to be efficient in the improvement of the melt flow. Various types and designs of baffles all influence the flow characteristics significantly. The "V" type baffles are better than the straight baffles for flow control. The "V" type baffle with four inclined holes at the sidewall away from the stopper rods is better in melt flow control than the one with one inclined hole at each sidewall. The combination of a well-designed turbulence inhibitor and an appropriate baffle shows high efficiency on improving the melt flow and an optimal proposal was presented. Plant trials indicate that, compared with the original tundish configuration in prototype, the inclusions reduce by 42% and the inclusion distribution of individual strands is more similar with the optimal one. The optimal tundish configuration effectively improves the melt flow in the ten-strand billet caster tundish.

关键词： billet continuous casting ten-strand caster tundish flow control device physical modeling plant trials

Flow Characteristics and Inclusion Removal in a Ten-strand Continuous Casting Tundish:Physical Modelling and Industrial Trials

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Journal of Iron and Steel Research International 2016年第2期23卷 92-97页

作者： shu-guo zheng miao-yong zhu Ye-lian ZHOU Wang SU School of Metallurgy Northeastern University

The flow characteristics and inclusion removal in a ten-strand continuous casting tundish were investigated with physical modelling and industrial trials. The results show that, among the strands, the strand with the mini mum dimensionless time of the first appearance of tracer at the tundish exit appears to be the worst one for inclusion removal, while the strand with the maximum dimensionless mean residence time shows the best inclusion removal efficiency. The inclusion number decreases with increasing inclusion size for all strands. The inclusion number distri bution among strands is the same for all inclusion sizes and the descending order of inclusion number is basically con sistent with the ascending order of dimensionless mean residence time among individual strands. However, when the strand with the minimum dimensionless time of the first appearance of tracer at the tundish exit is not the same one with the minimum dimensionless mean residence time, the former seems to be inferior to the latter for inclusion re moval.

关键词： multistrand continuous casting tundish flow characteristics inclusion removal physical modelling in-dustrial trial

Characteristic Parameters for Dendritic Microstructure of Solidification During Slab Continuous Casting

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Journal of Iron and Steel Research International 2009年第1期16卷 17-21页

作者： guo Wei zhu miao-yong School of Materials and Metallurgy Northeastern University Shenyang 110004 Liaoning China

The operating conditions during the continuous casting process have a great effect on the microstructure of slab solidification, including primary and secondary dendritic arm spacing. On the basis of the analysis of available work, a revised expression for describing secondary dendritic arm spacing during solidification of slab continuous casting was presented, and the relation between the ratio of primary dendritic arm spacing to secondary dendritic arm spacing and the cooling rate was obtained.

关键词： slab continuous casting dendritic solidification microstructure dendritic arm spacing

Quality control for bloom casting of YQ450NQR1 steel

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International Journal of Minerals,Metallurgy and Materials 2009年第1期16卷 32-36页

作者： yong Chen guo-rong Wu miao-yong zhu Materials and Metallurgy School Northeastern University Shenyang 110004 China Department of Material Research Panzhihua Iron and Steel Research Institute Panzhihua 617000 China

To reduce surface depression of a bloom, the primary cooling intensity was decreased, and the water distribution of mold wide and narrow faces was optimized. The length of secondary cooling zones and the specific water flow were increased, and the water flow distribution among the secondary cooling zones was adjusted to eliminate central defects, such as center looseness, central segregation, and center line cracks. The operation showed that the proportion of surface depression decreased from 37.22% to 2.87%, whereas the proportion of center looseness for 〈1.0 increased from 79.71% to 90.70%, the proportion of central segregation for 〈0.5 increased from 1.45% to 44.19%, and the proportion of center line cracks that are free increased from 39.13% to 62.79%. The qualified blooms are delivered to produce 310 Z-beam, whose yield strength is greater than 450 MPa.

关键词： corrosion resistant steel atmospheric corrosion bloom casting primary cooling secondary cooling quality control

Risk assessment of heavy metal contaminated soil in the vicinity of a lead/zinc mine

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Journal of Environmental Sciences 2005年第6期17卷 881-885页

作者： LI Jing XIE zheng-miao zhu yong-guan Ravi Naidu Institute for Soil and Water Resources and Environment Zhejiang University Hangzhou 310029 China Research Centre for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China Centre for Environmental Risk Assessment and Remediation University of South Australia Mawson Lakes SA 5095 Australia

Heavy metal contamination of soils through anthropogenic activities is a widespread and serious problem confronting scientists and regulators throughout the world. In this study we investigated the distribution, chemical species and availability of lead, zinc, cadmium and copper in nine surface（0 to 20 cm） soils from near an abandoned lead/zinc mine tailings located in Shaoxing, Zhejiang, China. Total heavy metal contents ranged from 5271 to 16369 mg/kg for Pb, 387 to 1221 mg/kg for Zn, 3.0 to 9.3 mg/kg for Cd and 65 to 206 mg/kg for Cu. In general, all heavy metals exceeded China National Standards for Soil Environmental Quality of Heavy Metals by a factor of 3-65 times. Comparison of the heavy metal concentrations（Pb, Zn, Cd and Cu） with clay content revealed a strongly significant relationship while significant relationship（ P 〈 0.001 ） was also obtained between Cd ＋ Zn and Pb ＋ Cu. Solid phase speciation of the soils using Tessier procedure showed that the heavy metals were distributed in the order： residual 〉〉 organically complexed-Fe-Mn oxides occluded 〉 carbonate bound 〉 exchangeable 〉 water soluble. In the organic matter fraction, the ratio of Pb（29.1% ） to its total concentration in the soils was higher than those of Zn（4.70% ）, Cd（3.16% ） and Cu（9.50% ）. The percentages of the water soluble and the exchangeable fractions of Pb（1.80% ） and Cd（2.74% ） were markedly greater than those of Zn（0.10% ） and Cu（0.15% ）, suggesting that Pb and Cd are relatively more mobile and hence more toxic in the contaminated soils. Strongly significant relationships between H20-Pb, H20-Zn and H20-Cu, strong positive correlations between H20-Pb, H20-Zn, H20-Cu and organic matter in soil were found. The content of H20-Pb, H20-Zn, H20-Cu was negatively correlated with pH values. The similar negative relationships between pH values and exchangeable heavy metals were also recorded. It is suggested that increasing soil pH or liming the soil could decrease bioavailability of heavy met

关键词： fractionation heavy metal mining tailings risk assessment soil pollution

Control Model of Bloom Dynamic Soft Reduction

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Journal of Iron and Steel Research International 2010年第9期17卷 31-35页

作者： CHEN yong JI Cheng zhu miao-yong WU guo-rong Department of Material Research Panzhihua Iron and Steel Research Institute Panzhihua 617000 Sichuan China School of Materials and Metallurgy Northeastern University Shenyang 110004 Liaoning China

There are significant effects of process parameters on internal qualities of bloom, and these process parameters are as follows. position and reduction amount, reduction distribution, reduction rate, and so on. Developing a control model is the key to apply soft reduction technology successfully. As the research object, 360 mm ×450 mm bloom caster in PISCO （Panzhihua Iron and Steel Co. ） has been studied, and the research method for control model of dynamic soft reduction has been proposed. On the basis of solidification and heat transfer model, the position of soft reduction and reduction distribution of each frame are determined according to the bloom temperature distribution and solid fraction in bloom center calculated. Production practice shows that the ratio of center porosity which is less than or equal to 1.0, increased to 97.27%, ratio of central segregation which is less than or equal to 0.5, increased to 80.91%, and ratio of central carbon segregation index which is more than or equal to 1.10, decreased to 4% with the applying model of dynamic soft reduction.

关键词： bloom continuous casting dynamic soft reduction control model center porosity central segregation

Anti-stroke biologics:from recombinant proteins to stem cells and organoids

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Stroke & Vascular Neurology 2024年第5期9卷 467-480页

作者： zhu-Wei miao Zhi Wang Si-Li zheng shu-Na Wang Chao-Yu miao Department of Pharmacology Second Military Medical University/Naval Medical UniversityShanghaiChina

The use of biologics in various diseases has dramatically increased in recent ***,a cerebrovascular disease,is the second most common cause of death,and the leading cause of disability with high morbidity *** biologics applied in the treatment of acute ischaemic stroke,alteplase is the only thrombolytic ***,current clinical trials show that two recombinant proteins,tenecteplase and non-immunogenic staphylokinase,are most promising as new thrombolytic agents for acute ischaemic stroke *** addition,stem cell-based therapy,which uses stem cells or organoids for stroke treatment,has shown promising results in preclinical and early clinical *** strategies for acute ischaemic stroke mainly rely on the unique properties of undifferentiated cells to facilitate tissue repair and ***,there is a still considerable journey ahead before these approaches become routine clinical *** includes optimising cell delivery methods,determining the ideal cell type and dosage,and addressing long-term safety *** review introduces the current or promising recombinant proteins for thrombolysis therapy in ischaemic stroke and highlights the promise and challenges of stem cells and cerebral organoids in stroke therapy.

关键词： dosage routine treatment

Physical and computational study of a novel submerged entry nozzle design for twin-roll casting process

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Journal of Iron and Steel Research International 2021年第11期28卷 1390-1399页

作者： Mian-guang Xu miao-yong zhu School of Mechanical Engineering Shandong University of TechnologyZibo 255000ShandongChina School of Metallurgy Northeastern UniversityShenyang 100819LiaoningChina

With significant emphasis on reducing the turbulence in the bath and the need for effective distribution of metal along the roller length in twin-roll casting,a novel submerged entry nozzle(SEN)configuration with two“gap regions”was ***“gap regions”of the new SEN divide the bath into two parts,the“upper melt bath”(casting region)and the“lower melt bath”(rolling region).The newly designed SEN was tested by using both full-scale water modeling experiments and numerical *** demonstrated that the turbulence could only be found near the rotating roller ***“gap regions”can make the near-wall flows more *** can also prevent the instabilities in the“upper melt bath”to be transferred to the“lower melt bath”,thus improving the stability of the ***,the novel SEN can stabilize the meniscus where the initial solidification *** is achieved by increasing the SEN immersion depth,which in turn,can enlarge the volume of the upper part of the bath.

关键词： Twin-roll casting Submerged entry nozzle Water model Numerical simulation