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Recycling of High Ferrous Bauxite Reducing Slag for Synthesis of CaAl_2Si_2O_8-Al_2O_3-CaAl_(12)O_(19) Composite

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Journal of Iron and Steel Research International 2016年第12期23卷 1255-1261页

作者： Ying-yi ZHANG Yuan-hong QI zong-shu zou College of Materials Science and Engineering Chongqing University State Key Laboratory of Advanced Steel Processes and Products Central Iron and Steel Research Institute School of Metallurgy Northeastern University

CaAl2 Si2 O8- Al2 O3- CaAl12 O19）（CAS2- Al2 O3 -CA6 ） composite was synthesized through reaction sintering alumina and bauxite reducing slag. The CAS2-Al2 O3-CA5 composite was mainly composed of α-Al2O3 , CAS2 , and CA6. Gehlenite （Ca2 Al2 SiO7 , C2 AS） phase was effectively transformed to CASe and CA6 through high-temperature reaction sintering under weak oxidizing atmosphere at 1400 ℃for 4 h. SEM （scanning electron microscopy） and EDS （energy dispersive spectroscopy） analysis indicated that black and needle-shaped Al2O3, rhombic or irregular polygonal shaped FeAl2O4 , and glassy phase Ca2 Al2 SiO7 disappeared after the reaction sintering. The light gray and flaky hexagon crystals of CaAl12 O19 （10 μm） and the grainy particles of Al2O3 （2-7 μm） were observed in the CASe-Al2 O3-CA6 composite. The gray crystals of CASe act as the binding phase and are distributed around CA6 and Al2O3. CAS2-Al2O3-CA6 composite exhibits high refractoriness and service temperature, which are 1 650 ℃ and 1 450 ℃, respectively. Reaction sintering of alumina and bauxite reducing slag is a feasible method for the synthesis of CAS2-Al2 O3-CA6 composite.

关键词： calcium hexaluminate composite reaction sintering bauxite reducing slag phase transformation

Numerical simulation of Marangoni effect induced by species transfer across iron droplet–molten slag interface

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Journal of Iron and Steel Research International 2023年第6期30卷 1109-1116页

作者： Ming-ming Li Zhen-qiang Wu Lin Li zong-shu zou Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgical Engineering Liaoning Institute of Science and TechnologyBenxi 117004LiaoningChina

A mathematical model accounting for unsteady mass transfer across interface of a stationary iron droplet immersed into molten slag was established through the volume of fluid coupled with level set *** Marangoni effect induced by mass transfer was reproduced successfully,and the hydrodynamic instability phenomena at the interface,such as the Marangoni convection flow,the evolution of the interfacial tension during the mass transfer,and the influence of Marangoni effect on the mass transfer rate,were *** results show that the Marangoni convection flow develops quickly and behaves as an ordered structure in the forms of four pairs of the convection cell at the edge of the droplet once the oxygen transfer across the interface *** average convection flow velocity along the interface is high,even more than 0.025 m/s,depending on the droplet diameter,which facilitates the mass *** Marangoni convection flow of the large droplet develops more easily than that of the small droplet,and the larger the droplet diameter is,the higher the convection flow velocity and the mass transfer rate ***,it is shown that the droplet diameter influences the impacting region of the Marangoni convection flow and its duration period.

关键词： Interfacial mass transfer Interfacial tension Marangoni effect Droplet Numerical simulation

Recovery of iron and calcium aluminate slag from high-ferrous bauxite by high-temperature reduction and smelting process

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International Journal of Minerals,Metallurgy and Materials 2016年第8期23卷 881-890页

作者： Ying-yi Zhang Wei Lü Yuan-hong Qi zong-shu zou College of Materials Science and Engineering Chongqing University State Key Laboratory of Advance Steel Processes and Products Central Iron and Steel Research Institute School of Material and Metallurgy Northeastern University

A high-temperature reduction and smelting process was used to recover iron and calcium aluminate slag from high-ferrous bauxite. The effects of w（CaO）/w（SiO_2） ratio, anthracite ratio, and reduction temperature and time on the recovery and size of iron nuggets and on the Al_2O_3 grade of the calcium aluminate slag were investigated through thermodynamic calculations and experiments. The optimized process conditions were the bauxite/anthracite/slaked lime weight ratio of 100：16.17：59.37, reduction temperature of 1450°C and reduction time of 20 min. Under these conditions, high-quality iron nuggets and calcium aluminate slag were obtained. The largest size and the highest recovery rate of iron nuggets were 11.42 mm and 92.79wt%, respectively. The calcium aluminate slag mainly comprised Ca_2 SiO_4 and Ca_（12）Al_（14）O_（33）, with small amounts of Fe Al_2O_4, CaAl_2O_4, and Ca_2Al_2SiO_7.

关键词： bauxite reduction smelting recovery rate calcium aluminate slag

Reduction and melting behavior of carbon composite lateritic bauxite pellets

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International Journal of Minerals,Metallurgy and Materials 2015年第4期22卷 381-388页

作者： Ying-yi Zhang Jie Zhao Yuan-hong Qi Xiang-li Cheng zong-shu zou State Key Laboratory of Advance Steel Processes and Products Central Iron and Steel Research Institute School of Material and Metallurgy Northeast University

Direct reduction of low-grade lateritic bauxite was studied at high temperature to recover Fe and beneficiate AlzO3 slag. The re- sults show that a metallization rate of 97.9% and a nugget recovery rate of 85.1% can be achieved when the reducing and melting tempera- tures are 1350 and 1480℃, respectively. Moreover, a higher-grade calcium aluminate slag （A1203 = 50.52wt%） can also be obtained, which is mainly composed of ct-A1203, hercynite （FeAI：O4）, and gehlenite （Ca2A12SiO7）. In addition, high-quality iron nuggets have been produced from low-grade lateritic bauxite. The nugget is mainly composed of iron （93.82wt%） and carbon （3.86wt%）, with almost no gangue （slag）.

关键词： bauxite ore pellets direct reduction process melting behavior metallization

Effect of screw casing structure on descending of burdens in COREX shaft furnace

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Journal of Iron and Steel Research International 2017年第1期24卷 18-26页

作者： Zi-long Qiu Zhi-guo Luo Heng Zhou Ren Chen Feng Wang zong-shu zou College of Metallurgy Northeastern University College of Metallurgy Engineering Liaoning Institute of Science and Technology

COREX shaft furnace（SF）is a typical screw feeder with a storage container coupled with eight screw casings and *** structure of screw casing plays an important role in the moving behavior of burdens,stress distribution,abrasive wear of screws,and energy consumption during the operation of ***,a three-dimensional semi-cylindrical model of actual size of COREX-3000 SF was established based on discrete element method to investigate the influences of screw casing *** results show that the increase in the gap between the outside of screw flight and screw casing is beneficial for the smooth operation of SF,resulting in uniform descending velocity along the radius of SF in the lower part,decreasing the size of recirculation region,and alleviating stress concentration in the screw ***,raising the gap appropriately is also beneficial to weaken screw abrasive wear,decrease energy consumption,and then prolong the service life of the ***,enlarging the gap also leads to more undesired high temperature reduction gas into the SF from melter gasifier,thereby deteriorating the operation of ***,an ideal distance exists between the outside of the screw flight and the screw casing,which is suggested to be equal to the average of particle diameter.

关键词： COREX shaft furnace Screw casing structure Discrete element method Recirculation structure Screw abrasive wear

Influence of Screw Design on Burden Descending Velocity and Particle Segregation in COREX Shaft Furnace

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Journal of Iron and Steel Research International 2016年第6期23卷 516-524页

作者： Hai-feng LI Heng ZHOU Tao ZHANG Yang YOU zong-shu zou Wan-ren XU School of Metallurgy Northeastern University Baoshan Iron and Steel Co. Ltd.

COREX shaft furnace（SF）is an industrial system that employs screw feeders;thus,the burden descending velocity and particle segregation in the SF can be directly affected by the design of screw.A three-dimensional actual size model of COREX-3000 SF was established using the discrete element *** types of burdens,including pellet,ore,flux and coke,were considered in this *** this consideration,the effect of screw design on solid flow was *** showed that,in the base case,burdens fell primarily down from the first flight of the *** burden descending velocities were nearly uniform in the peripheral direction and decreased along the radial *** addition,the normalized particle size increased in the center area and decreased in the wall *** the flight diameter of screw benefited an even flow pattern and restrained the rolling tendency of burden from the edge to center *** optimized case was also proposed,in which a uniform solid flow profile could be obtained and the evenness of descending velocity along the radius could be greatly improved.

关键词： screw COREX descending burden normalized radius Velocity segregation torque pellet

Medium oxygen enriched blast furnace with top gas recycling strategy

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Journal of Iron and Steel Research International 2017年第8期24卷 778-786页

作者： Wei Zhang Zheng-liang Xue Ju-hua Zhang Wei Wang Chang-gui Cheng zong-shu zou The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081HubeiChina School of Metallurgy Northeastern UniversityShenyang 110004LiaoningChina

Top gas recycling oxygen blast furnace（TGR-OBF）process is a promising ironmaking *** biggest challenge of the TGR-OBF in operation is the dramatic decrease of top gas volume（per ton hot metal）,which once led to hanging-up and shutdowns in practice of the *** order to avoid this weakness,the strategy of medium oxygen blast furnace was *** maneuverable zone of the TGR-OBF was determined by the top gas volume,which should not be far from the data of the traditional blast *** deviation of ±12.5% was used,and then the maneuverable blast oxygen content is from 0.30 to 0.47 according to the *** flame temperature and the top gas volume have no much difference compared to those of the traditional blast *** minimum carbon consumption of 357 kg per ton hot metal in the maneuverable zone occurs at the oxygen content of 0.30（fuel saving of 14%）.In the unsteady evolution,the N2 accumulation could approach nearly zero after the recycling reached 6 *** far,some TGR-OBF industrial trials have been carried out in different countries,but the method of medium oxygen enriched TGR-OBF has not been implemented,because the accumulation of N2 was worried *** presented strategy of medium oxygen enriched TGR-OBF is applicable and the strategy with good operational performance is strongly suggested as a forerunner of the full oxygen blast furnace.

关键词： Oxygen blast furnace Top gas recycling Top gas volume Carbon consumption Operation Emission Optimization

Influence of Cohesive Zone Shape on Solid Flow in COREX Melter Gasifier by Discrete Element Method

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Journal of Iron and Steel Research International 2015年第4期22卷 304-310页

作者： Li-hao HAN Zhi-guo LUO Heng ZHOU zong-shu zou Yu-zhu ZHANG School of Materials and Metallurgy Northeastern University College of Metallurgy and Energy Hebei United University

Based on the principle of discrete element method （DEM）, a 2D slot model of a COREX melter gasifier was established to analyze the influence of cohesive zone shape on solid flow, including mass distribution, velocity distribution, normal force distribution and porosity distribution at a microscopic level. The results show that the co- hesive zone shape almost does not affect the particle movement in the upper shaft and deadman shape. The particles in the lower central bottom experience large normal force to support the particles above them, while particles around the raceway and in the fast flow zone exhibit weak force network. The porosity distribution was also examined under three kinds of cohesive zones. Like the velocity distribution, the whole packed bed can be divided into four main re- gions. With the increase of cohesive zone position, the low porosity region located in the root of cohesive zone increa- ses. And the porosity distribution becomes asymmetric in the case of biased cohesive zone.

关键词： COREX melter gasifier discrete element method porosity distribution cohesive zone shape solid flow

DEM Simulation of Solid Flow Including Asymmetric Phenomena in COREX Shaft Furnace

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Journal of Iron and Steel Research International 2015年第12期22卷 1098-1106页

作者： Zhi-guo LUO Heng ZHOU Tao ZHANG Yang YOU Hai-feng LI zong-shu zou School of Materials and Metallurgy Northeastern University Key Laboratory of Ecological Utilization of Multi-metallic Mineral of Education Ministry Northeastern University

Based on the principles of the discrete element method （DEM）, a scaled-down model was established to analyze burden descending behavior, including asymmetric phenomena, throughout an entire COREX shaft furnace （SF）. The applicability of the DEM model was validated by determining its accordance with a previous experiment. The effects of discharge rate and abnormal conditions on solid flow were described in terms of solid flow pattern and microscopic analysis. Results confirmed that the solid flow of the COREX SF can be divided into four different flow regions; the largest normal force exists at the top of the man-made dead zone, and the weak force network exists in the funnel flow region. The basic solid flow profile was identified as a clear Flat→U→W type. Increasing the dis- charge rate decreased the quasi-stagnant zone size, but did not affect the macroscopic motion of particles or the shape of patterns above the bustle. For asymmetric conditions, in which particles were discharged at different rates, the solid flow patterns were asymmetric. Under an abnormal condition where no particles were discharged from the left outlet, a sizeable stagnant zone was formed opposite to the working outlet, and ＂motionless＂ particles located in the left stagnant zone showed potential to increase the period of static contacts and sticking effect.

关键词： COREX shaft furnace solid flow discrete element method asymmetric phenomena