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International Journal of Minerals,Metallurgy and Materials 2019年第2期26卷 186-193页

作者： Peng Fei Yi Min cheng-jun liu Mao-fa Jiang Key Laboratory for Ecological Metallurgy of Multimetallic Mineral ((Ministry of Education)) School of Metallurgy Northeastern University Key Laboratory for Ecological Metallurgy of Multimetallic Mineral (Ministry of Education)

For the control of surface defects in interstitial-free(IF) steel, quantitative metallographic analyses of near-surface inclusions and surface liquid flow detection via the nail-board tipping method were conducted. The results show that, at casting speeds of 0.8 and 1.0 m/min, a thin liquid mold flux layer forms and non-uniform floating of argon bubbles occurs, inducing the entrainment and subsequent entrapment of the liquid flux; fine inclusion particles of Al_2O_3 can also aggregate at the solidification front. At higher casting speeds of 1.4 and 1.6 m/min, the liquid mold flux can be entrained and carried deeper into the liquid steel pool because of strong level fluctuations of the liquid steel and the flux. The optimal casting speed is approximately 1.2 m/min, with the most favorable surface flow status and, correspondingly, the lowest number of inclusions near the slab surface.

关键词： non-metallic inclusions distribution casting speed surface flow

Structural behavior of F-in mould flux melt of CaO-SiO2-Al2 O3-Na2O-CaF2 system

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Journal of Iron and Steel Research International 2017年第11期24卷 1152-1158页

作者： Qiang Gao Yi Min cheng-jun liu Mao-fa Jiang Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina

The influence of fluorine on the structure of CaO Si（）e-Al2Oa Na2O-CaF2 continuous-casting-type slag was measured by Raman spectroscopy, and the degree of polymerization of mould flux and the structural behavior of F- in the melt were investigated by classifying and quantifying the structural species of F ions. The results exhibit that the main structural units of Si O tetrahedra are Q1, Q1 and Q2, and the actual measured number of non bridging oxygen ions in the [SiO4 ]-tetrahedra （denoted by NBO/T） in creases from 2. 73 to 3.44 with increasing the molar ratio of F to （F＋O）（denoted by XF/X（F-O ） from 0.06 to 0. 19. It means that the degree of polymerization o1 meh structure decreases with an increase in XE/X（F＋O）. In addition, most of F- ions were distributed in Si-O tetrahedra and Al-O tetrahedra. With increasing XF/X（F＋O）, the complex structural units Al-Otetrahedra are gradually replaced hy discrete structural units A1F4 because of the breakage of Al-O bonds in Al-Otetrahedra by F ions, and the SiO （bridging oxygen） bonds of SiO tetrahedra are broken to form [SiOnF1-n]-tetrahedra by F ions coordinating with Si4 ＋ .

关键词： Mould flux F- ion Melt structure Polymerization degree

Microstructural evolution of Al-8.59Zn-2.00Mg-2.44Cu during homogenization

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International Journal of Minerals,Metallurgy and Materials 2014年第12期21卷 1215-1221页

作者： Wen-xiang Shu jun-cheng liu Long-gang Hou Hua Cui jun-tao liu Ji-shan Zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing School of Materials Science and Engineering University of Science and Technology Beijing State Key Laboratory for Fabrication and Processes of Nonferrous Metals General Research Institute for Nonferrous Metals

The microstructural evolution and phase transformations of a high-alloyed Al-Zn-Mg-Cu alloy （Al-8.59Zn-2.00Mg-2.44Cu,wt%） during homogenization were investigated. The results show that the as-cast microstructure mainly contains dendritic α（Al）, non-equilibrium eutectics （α（Al）＋ Mg（Zn,Al,Cu）2）, and the θ （Al2Cu） phase. Neither the T （Al2Mg3Zn3） phase nor the S （Al2CuMg） phase was found in the as-cast alloy. The calculated phase components according to the Scheil model are in agreement with experimental results. During homogenization at 460℃, all of the θ phase and most of the Mg（Zn,Al,Cu）2 phase were dissolved, whereas a portion of the Mg（Zn,Al,Cu）2 phase was transformed into the S phase. The type and amount of residual phases remaining after homogenization at 460℃ for 168 h and by a two-step homogenization process conducted at 460℃ for 24 h and 475℃ for 24 h （460℃/24 h ＋ 475℃/24 h） are in good accord with the calculated phase diagrams. It is concluded that the Al-8.59Zn-2.00Mg-2.44Cu alloy can be homogenized adequately under the 460℃/24 h ＋ 475℃/24 h treatment.

关键词： aluminum alloys homogenization microstructural evolution phase composition thermodynamic calculations

Formation and evolution behavior of inclusions in Al-killed resulfurized free-cutting steel with magnesium treatment

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Journal of Iron and Steel Research International 2020年第6期27卷 631-642页

作者： Qing-song Zhang Yi Min Jiu-jian Xu cheng-jun liu Key Laboratory for Ecological Metallurgy of Multimetallic Ores(Ministry of Education) Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang110819LiaoningChina

To reveal the formation and evolution behavior of inclusions during magnesium treatment and resulfurization in Al-killed free-cutting steel, both laboratory experiments and thermodynamic calculations were carried out. The extracted samples were polished and analyzed by scanning electron microscopy and energy-dispersive spectroscopy. The results indicated that MgO formed immediately and then transferred to MgO·Al2O3 with the homogenization of [Mg] in steel in the case of low magnesium addition (w[Mg] < 0.0020%). However, MgO would keep stable in the case of high magnesium addition (w[Mg] ≥ 0.0020%). In the process of resulfurization, the addition of sulfur forced the transformation of MgO to MgO·Al2O3 accompanied with the formation of MgS if the mass fraction of [S] in steel was in the range 0.15%-0.70%. MgS precipi-tated as a solid solution containing a quantity of MnS, and the composition of the sulfide solution was calculated to be (Mg0.85Mn0.15)S when the mass fraction of [Mn] was 1.2%. The formation mechanisms of inclusions after magnesium and sulfur additions were discussed comprehensively, and proper models for the evolution of inclusions were set up.

关键词： Magnesium treatment Resulfurization Inclusion Thermodynamics Free-cutting steel

Review on monitoring and prevention technologies of splashing induced by inappropriate slag foaming in BOF

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Journal of Iron and Steel Research International 2023年第9期30卷 1661-1674页

作者： Rui-fang Wang Bo Zhang cheng-jun liu Mao-fa Jiang Key Laboratory for Ecological Metallurgy of Multimetallic Ores(Ministry of Education) Northeastern UniversityShenyang 110819LiaoningChina School of Metallurgy Northeastern UniversityShenyang 110819LiaoningChina State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization Baotou Research Institute of Rare EarthsBaotou 014030Inner MongoliaChina

Basic oxygen steelmaking(BOS)is the most frequently used method to produce molten steel,which is being developed to meet the requirements of being safe,efficient,clean,and *** the BOS process,splashing events cause undesirable consequences,such as casualties,low efficiency,environmental pollution,and uncontrollable *** causes of three types of splashing(eruptive,foaming,and metallic splashing)were unraveled and it is concluded that inappropriate foaming is the root cause of splashing.A variety of monitoring techniques for splashing have been developed to measure real-time slag foaming in a basic oxygen furnace(BOF).The audiometry technique with flexible operation and high accuracy was comprehensively introduced with a practical *** on the formation mechanisms,the countermeasures for the three types of splashing were proposed to regulate slag foaming in a BOF by integrating diverse measures in terms of raw materials,slag forming,blowing pattern,and the use of splashing regulating *** work should emphasise an automatic action for these prevention measures in response to the splashing risk from the monitoring technology,promoting the progress of intelligent steelmaking.

关键词： Steelmaking Splashing Slag foaming Monitoring Prevention

Growth behavior of spinel in stainless steel slag during cooling process

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Journal of Iron and Steel Research International 2018年第11期25卷 1131-1139页

作者： Long-hu Cao cheng-jun liu Qing Zhao Mao-fa Jiang Key Laboratory for Ecological Metallurgy of Multimetallic Ores (Ministry of Education) Northeastern University Shenyang 110819LiaoningChina School of Metallurgy Northeastern University Shenyang 110819LiaoningChina

Spinel is an appropriate phase for sequestrating chromium in stainless steel slag to prevent chromium from polluting,and the crystal size of spinel has a significant effect on the stability of chromium and the extraction efficiency of *** enrichment behavior of chromium in spinel during cooling process was investigated,and the growth process of spinel was studied based on the crystal size distribution *** results showed that the enrichment degree of chromium in spinel increased from 88.5% to nearly 100% during the cooling process from 1773 to 1573 K at a rate of 5 K/*** mean diameter of spinel in stainless steel slag had an obvious growth in the cooling process,and a rapid growth of spinel occurred during the cooling process from 1623 to 1523 *** results indicated that the leaching amount of chro- mium could reduce to less than 0.01 mg/L by controlling the cooling *** growth mechanism of spinel was investigated and proposed to consist of two stages:in the first stage,the spinel was in the surface-controlled growth with a decaying nucleation rate from 1773 to 1573 K,and in the second stage,the growth mechanism was transformed to supply- controlled Ostwald ripening-below 1573 K.

关键词： Stainless steel slag Spinel Chromium Growth mechanism Crystal size distribution

Decomposition mechanism of chromite in sulfuric acid–dichromic acid solution

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International Journal of Minerals,Metallurgy and Materials 2017年第12期24卷 1361-1369页

作者： Qing Zhao cheng-jun liu Bao-kuan Li Mao-fa Jiang Key Laboratory for Ecological Metallurgy of Multimetallic Ores(Ministry of Education) Northeastern UniversityShenyang 110819China School of Metallurgy Northeastern UniversityShenyang 110819China

The sulfuric acid leaching process is regarded as a promising, cleaner method to prepare trivalent chromium products from chromite; however, the decomposition mechanism of the ore is poorly understood. In this work, binary spinels of Mg–Al, Mg–Fe, and Mg–Cr in the powdered and lump states were synthesized and used as raw materials to investigate the decomposition mechanism of chromite in sulfuric acid–dichromic acid solution. The leaching yields of metallic elements and the changes in morphology of the spinel were studied. The experimental results showed that the three spinels were stable in sulfuric acid solution and that dichromic acid had little influence on the decomposition behavior of the Mg–Al spinel and Mg–Fe spinel because Mg^(2+), Al^(3+), and Fe^(3+) in spinels cannot be oxidized by Cr^(6+). However, in the case of the Mg–Cr spinel, dichromic acid substantially promoted the decomposition efficiency and functioned as a catalyst. The decomposition mechanism of chromite in sulfuric acid–dichromic acid solution was illustrated on the basis of the findings of this study.

关键词： hydrometallurgy chromite sulfuric acid leaching spinel decomposition mechanism

Effect of Al2O3 modification on enrichment and stabilization of chromium in stainless steel slag

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Journal of Iron and Steel Research International 2017年第3期24卷 258-265页

作者： Long-hu Cao cheng-jun liu Qing Zhao Mao-fa Jiang Key Laboratory for Ecological Metallurgy of Multimetallic Mineral (Ministry of Education) Northeastern University Shenyang 110819 Liaoning China

Spinel phase is considered to be the optimal phase for stabilization of chromium in stainless steel *** order to restrain chromium leaching from slag for the effective environmental protection,Al2O3 was utilized for the modification treatment,and the effects on the enrichment and stabilization of chromium were investigated. The mineral phases and the existence state of chromium in slag with various Al2O3 contents at different basicities（ w（CaO）/w（SiO2） were analyzed by scanning electron microscopy-energy dispersive spectroscopy（ SEM-EDS） and X-ray diffraction（ XRD）. The results showed that chromium mainly existed in the glass and spinel phases at basicity of 1. 0 and 1. 5. As the slag basicity increased to 2. 0,chromium was also found in periclase phase. Al2O3 in the stainless steel slag reacted with MgO and Cr2O3,which could generate the Al-rich Mg（CrxAl（1- x））2O4 solid solution. Moreover,the addition of Al2O3 was favorable to reduce the solubility of chromium oxide in liquid phase and suppress the precipitation of periclase phase. The experimental results demonstrated that Al2O3 modification has a positive influence on the enrichment and the stabilization of chromium in the stainless steel slag.

关键词： Stainless steel slag Chromium Spinel Al2O3 modification Enrichment Stabilization

Study on mechanisms of different sulfuric acid leaching technologies of chromite

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International Journal of Minerals,Metallurgy and Materials 2017年第9期24卷 983-990页

作者： Pei-yang Shi cheng-jun liu Qing Zhao Hao-nan Shi Key Laboratory for Ecological Metallurgy of Multimetallic Ores Northeastern University Northeastern University School of Metallurgy Northeastern University Faculty of Chemical Environmentaland Biological Science and TechnologyDalian University of Technology

The extraction of chromate from chromite via the sulfuric acid leaching process has strong potential for practical use because it is a simple and environmentally friendly process. This paper aims to study the sulfuric acid leaching process using chromite as a raw material via either microwave irradiation or in the presence of an oxidizing agent. The results show that the main phases in Pakistan chromite are ferrichromspinel, chrompicotite, hortonolite, and silicate embedded around the spinel phases. Compared with the process with an oxidizing agent, the process involving microwaves has a higher leaching efficiency. When the mass fraction of sulfuric acid was 80% and the leaching time was 20 min, the efficiency could exceed 85%. In addition, the mechanisms of these two technologies fundamentally differ. When the leaching was processed in the presence of an oxidizing agent, the silicate was leached first and then expanded. By contrast, in the case of leaching under microwave irradiation, the chromite was dissolved layer by layer and numerous cracks appeared at the particle surface because of thermal shock. In addition, the silicate phase shrunk instead of expanding.

关键词： chromite leaching mechanisms microwave leaching sulfuric acid microanalysis

Effects of Different Oxidants on HCl-based Pickling Process of 430 Stainless Steel

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Journal of Iron and Steel Research International 2016年第8期23卷 778-783页

作者： Qiong XIE Pei-yang SHI cheng-jun liu Mao-fa JIANG Key Laboratory for Ecological Metallurgy of Multimetallic Mineral of Ministry of Education Northeastern University

To shorten the time required for the pickling process and to enhance the quality of ferritic stainless steel plates,the effects of oxidants including hydrogen peroxide（H2O2）,potassium permanganate（KMnO4）,and potassium chlorate（KClO3）on the pickling behavior in HCl-based electrolyte as well as the surface quality of hot-rolled and blasted 430 stainless steel（430-SS）were *** were conducted using mass-loss tests,microstructure analyses,potentiodynamic polarization curves,and electrochemical impedance spectroscopy *** results showed that the addition of oxidants substantially accelerated the pickling process of 430-SS by enhancing the cathodic reaction rate and reducing the charge transfer *** electrolytes comprising 5-8mass% HCl at a temperature of 40-60 ℃ and at the same concentration within the range from 0to 2mass%,H2O2 was demonstrated to be superior to KMnO4 and KClO3in accelerating the pickling *** surface quality of 430-SS pickled in the presence of H2O2 was better than those of specimens pickled in the presence of KMnO4 and KClO3 when the removal of the oxide layer,intergranular corrosion,and surface roughness were collectively *** 1mass% H2O2 was added,the mass loss rate of 430-SS was increased by 629%and no residual oxide layer or intergranular corrosion was observed on the surface of the steel;in addition,the roughness was only 1.7μm.H2O2 was determined to be a better oxidant than KMnO4 and KClO3 when the pickling process,surface quality,solution recycling,and environment protection were considered as a whole.

关键词： roughness cathodic electrolyte impedance stainless potassium recycling oxidant accelerating immersed