Analysis of compressive strength and microstructure during mineralization process of flux based pellets
NI Jie1, SHI Xuefeng1, BAI Chenchen1, ZHANG Yuzhu1, LIU Lianji2, XIAO Hong2
1. School of Metallurgy and Energy, North China University of Technology, Tangshan 063210, Hebei, China; 2. Office of the Chief Engineer, Tangshan Iron and Steel Group Co., Ltd., Tangshan 063011, Hebei, China
Abstract：The compressive strength of the pellets is one of the main indicators to measure whether the pellets can enter the blast furnace smelting, and the compressive strength of the pellets is determined by the mineral composition and microstructure of the pellet. Zhongguan iron ore is used as the basic pelletizing raw material, and low-silica flux pellets are prepared by calcium and magnesium additives. By systematically studying the microstructure and mineral distribution morphology of pellets under different MgO content, alkalinity and SiO2 content, the change law of compressive strength of low silicon flux pellets was revealed. The results show that increasing the roasting temperature and alkalinity can effectively improve the compressive strength of pellets. When the SiO2 content was low, the pellets are mainly consolidated by hematite crystals, and the strength change is not obvious. When the mass percent of SiO2 increased to 3.5% and 4.0%, respectively, the hematite crystals were gradually interconnected into pieces, and the crystals gradually became coarse and compact, the structural strength was strong, and the compressive strength of the pellets increased. With the increase of alkalinity, hematite recrystallization is better, there are few granular alone and the crystals are interconnected into blocks, magnetite is reduced, the liquid phase of low silicon flux pellets increases during the roasting process, and the liquid phase of calcium ferrite system appears to increase the strength of the pellets. With the increase of MgO percentage, more Mg2+ entered the magnetite phase, which made up for the lattice defect, and the magnesium ferrite content increased and appeared needle-like or flake distribution in hematite, which inhibited the formation of liquid phase during the roasting process, and made the pores inside the pellet smaller during the cooling process, thereby improving the density of the pellet and enhancing the strength of the pellet. The content of MgO continued to increase, the content of magnetite and glass phase increased, and the content of hematite and calcium ferrite decreased relatively. And because the increase of Fe3O4 will reduce the conjunctive performance of Fe2O3, and eventually lead to the decrease of the compressive strength of the pellets. The above studies provide theoretical guidance and reference for the exploration of low silica magnesium flux pellets.
倪杰, 师学峰, 白晨晨, 张玉柱, 刘连继, 肖洪. 熔剂性球团成矿过程抗压强度及微观结构分析[J]. 钢铁, 2024, 59(2): 36-43.
NI Jie, SHI Xuefeng, BAI Chenchen, ZHANG Yuzhu, LIU Lianji, XIAO Hong. Analysis of compressive strength and microstructure during mineralization process of flux based pellets[J]. Iron and Steel, 2024, 59(2): 36-43.
[1] 王晓磊, 师学峰, 胡长庆, 等. w(MgO)对镁质酸性球团制备及冶金性能的影响[J]. 烧结球团, 2020, 45(1): 35. (WANG X L, SHI X F, HU C Q, et al. Effect of w(MgO) on the preparation and metallurgical properties of magnesium acidic pellets[J]. Sintering and Pelletizing, 2020, 45(1):35.) [2] 周明顺, 尚策, 赵东明, 等. 鞍钢炼铁原料准备新技术与新工艺自主创新与展望[J]. 鞍钢技术, 2019(6): 1. (ZHOU M S, SHANG C, ZHAO D M, et al. Independent innovation of new technology and new process for preparing ironmaking raw materials in ansteel and their outlook[J]. Angang Technology, 2019(6): 1.) [3] 易可. 国内外高炉球团矿使用比例[J]. 烧结球团, 2008, 33(4): 53. (YI K. Pelletizing production with using mixture of BF gas and BOF gas in JIUGANG[J]. Sintering and Pelletizing, 2008, 33(4): 53.) [4] 胡守景. 熔剂性球团矿生产的理论与技术[J]. 城市建设理论研究(电子版), 2020, 324(6): 40. (HU S J. Theory and technology of flux pellet production[J]. Theoretical Research in Urban Construction, 2020, 324 (6): 40.) [5] 于洪军,路明,王兴锋,等.铁矿粉粒度组成对球团矿性能影响的研究进展[J].冶金能源,2022,41(1):21. (YU H J,LU M, WANG X F, et al.Research progress on the effect of iron fine particle size on pellet properties[J]. Energy for Metallurgical Industry,2022,41(1):21.) [6] 薄胜岳, 胡长庆, 师学峰, 等. 镁质熔剂性球团矿发展现状及展望[J]. 华北理工大学学报(自然科学版), 2021, 43(3): 40. (BO S Y, HU C Q, SHI X F, et al. Development and prospect of magnesium flux pellets[J]. Journal of North China University of Science and Technology(Natural Science), 2021, 43(3): 40.) [7] DISHWAR R K, MANDAL A K, SINHA O P. Studies on highly fluxed iron ore pellets hardened at 1 100 ℃ to 1 200 ℃[J]. Metallurgical and Materials Transactions B, 2019, 50(2): 617. [8] 刘然, 张智峰, 刘小杰, 等. 低碳绿色炼铁技术发展动态及展望[J]. 钢铁, 2022, 57(5): 1. (LIU R, ZHANG Z F, LIU X J, et al. Development trend and prospect of low carbon green ironmaking technology[J]. Iron and Steel, 2022, 57(5):1.) [9] 王新东, 金永龙. 高炉使用高比例球团的战略思考与球团生产的试验研究[J]. 钢铁, 2021, 56(5): 7. (WANG X D, JIN Y L. Strategy analysis and testing study of high ratio of pellet utilized in blast furnace[J]. Iron and Steel, 2021, 56(5): 7.) [10] 汪书朝. 熔剂性球团生产过程回转窑内温度场和流场分布数值模拟[D]. 唐山:华北理工大学, 2019. (WANG S C. Numerical Simulation of Temperature Field and Flow Field Distribution in Rotary Kiln during Flux Pellet Production[D].Tangshan:North China University of Science and Technology,2019.) [11] 王海风, 裴元东, 张春霞, 等. 中国钢铁工业烧结/球团工序绿色发展工程科技战略及对策[J]. 钢铁, 2016, 51(1): 1. (WANG H F, PEI Y D, ZHANG C X, et al. Green development of sintering/pellet procedure in China iron and steel industry[J]. Iron and Steel, 2016, 51(1): 1.) [12] 胡启晨. 传统高炉炼铁流程面临的问题和应对策略[J]. 河北冶金, 2017(12): 28. (HU Q C. Problems and counter measures for the traditional blast furnace iron aking process[J]. Hebei Metallurgy, 2017(12): 28.) [13] 邢奕, 张文伯, 苏伟, 等. 中国钢铁行业超低排放之路[J]. 工程科学学报, 2021, 43(1): 1. (XING Y, ZHANG W B, SU W, et al. Research of ultra-low emission technologies of the iron and steel industry in China[J]. Chinese Journal of Engineering, 2021, 43(1): 1.) [14] 黄导, 陈丽云, 张临峰, 等. 推进节能环保技术管理升级 促进钢铁工业绿色转型[J]. 钢铁, 2015, 50(12): 1. (HUANG D, CHEN L Y, ZHANG L F, et al. Boost the upgrade of energy conservation and environmental protection technology management and promote the green transformation of iron and steel industry[J]. Iron and Steel, 2015, 50(12): 1.) [15] 张福明, 程相锋, 银光宇, 等. 国内外低碳绿色炼铁技术的发展[J]. 炼铁, 2021, 40(5): 1. (ZHANG F M, CHENG X F, YIN G Y, et al. Development of low-carbon green ironmaking technology at home and abroad[J]. Ironmaking, 2021, 40(5): 1.) [16] 王新东, 金永龙. “双碳”背景下高炉使用高比例球团的展望[J]. 过程工程学报, 2022, 22(10): 1379. (WANG X D, JIN Y L. Prospect on high ratio pellet utilized in blast furnace under the background of carbon peaking and carbon neutrality[J]. The Chinese Journal of Process Engineering, 2022, 22(10): 1379.) [17] 许满兴, 张玉兰. 新世纪我国球团矿生产技术现状及发展趋势[J]. 烧结球团, 2017, 42(2): 25. (XU M X, ZHANG Y L. Analysis of pellet technology and production of China in 21 st century[J]. Sintering and Pelletizing, 2017, 42(2): 25.) [18] 于立梅, 张若鹏, 任翠英. 钢铁行业低碳发展标准体系建设研究[J]. 中国冶金, 2021, 31(9): 135. (YU L M, ZHANG R P, REN C Y. Research on establishing standards system of low- carbon development for iron and steel industry[J]. China Metallurgy, 2021, 31(9): 135.) [19] 徐子轩,姜鑫,何佳,等.钙质熔剂对熔剂性球团矿强度的影响[J].中国冶金,2023,33(9):11. (XU Z X,JIANG X, HE J,et al. Effects of calcium flux on fluxed pellets strength[J].China Metallurgy,2023,33(9):11.) [20] 张福明. 中国高炉炼铁技术装备发展成就与展望[J]. 钢铁, 2019, 54(11): 1. (ZHANG F M. Prospect and development achievements of blast furnace ironmaking technologies and equipments in China[J]. Iron and Steel, 2019, 54(11): 1.) [21] 王新东, 李建新, 胡启晨. 基于高炉炉料结构优化的源头减排技术及应用[J]. 钢铁, 2019, 54(12): 104. (WANG X D, LI J X, HU Q C. Application practice of source and process sulfur nitrate reduction technology based on optimization of blast furnace charge structure[J]. Iron and Steel, 2019, 54(12): 104.) [22] 李磊, 豆远波, 王宇, 等. 大比例球团矿在包钢2 200 m3高炉的生产实践[J]. 包钢科技, 2022, 48(4): 13. (LI L, DOU Y B, WANG Y, et al. Production practices on large proportion of pellet in 2 200 m3 blast furnace of baotou steel[J]. Science and Technology of Baotou Steel, 2022, 48(4): 13.) [23] 王维兴. 提高高炉炉料中球团矿配比、促进节能减排[J]. 冶金管理, 2018, 355(9): 53. (WANG W X. Increase the ratio of pellets in blast furnace charge to promote energy conservation and emission reduction[J]. China Steel Focus, 2018, 355(9): 53.) [24] 张淑会, 王宝勇, 兰臣臣, 等. 球团矿化学成分控制现状及展望[J]. 钢铁, 2020, 55(8): 19. (ZHANG S H, WANG B Y, LAN C C, et al. Prospects and present status of pellets chemical composition control[J]. Iron and Steel, 2020, 55(8): 19.) [25] 汪书朝, 师学峰, 张巧荣, 等. 镁质球团矿焙烧固结及其机理研究[J]. 钢铁钒钛, 2018, 39(5): 79. (WANG S C,SHI X F,ZHANG Q R, et al. Roasting and induration mechnism in magnesia pellet[J]. Iron Steel Vanadium Titanium,2018, 39(5): 79.) [26] 曲旭东,李坚毅,折媛.碱度对熔剂性球团抗压强度及冶金性能的影响[J].冶金能源,2022,41(1):15.(QU X D,LI J Y,SHE Y.Effect of basicity on the compressive strength and metallurgical properties of fluxed pellets[J]. Energy for Metallurgical Industry,,2022,41(1):15.) [27] 李建鹏, 卢建光, 刘小杰, 等. 球团矿中MgO含量对炉料熔滴性能的影响[J]. 中国冶金, 2022, 32(4): 21. (LI J P, LU J G, LIU X J, et al. Effect of MgO content in pellets on softening-dripping properties of burden in BF[J]. China Metallurgy, 2022, 32(4): 21.) [28] 胡长庆, 王晓磊, 师学峰, 等. 碱度及MgO含量对FeOx-SiO2-CaO-MgO-Al2O3体系矿物组成的影响[J]. 钢铁研究学报, 2020, 32(2): 103. (HU C Q,WANG X L,SHI X F,et al. Effect of alkalinity and MgO content on mineral composition and microstructure of FeOx-SiO2-CaO-MgO-Al2O3 system[J]. Journal of Iron and Steel Research,2020, 32(2): 103.) [29] 王晓磊, 师学峰, 胡长庆, 等. 高硅镁质熔剂性球团焙烧试验研究[J]. 矿产综合利用, 2020(4): 87. (WANG X L, SHI X F, HU C Q, et al. Experimental study on roasting of high silica magnesium flux pellet[J]. Multipurpose Utilization of Mineral Resources, 2020(4): 87.) [30] 王国华,崔雅茹. FexO-SiO2-CaO-MgO-“NiO”系镍渣势函数及分子动力学模拟[J]. 计算物理, 2021, 38(2): 215.(WANG G H, CUI Y R. Potential function and molecular dynamics simulation for FexO-SiO2-CaO-MgO-"NiO" nickel slag[J]. Chinese Journal of Computational Physics, 2021, 38(2): 215.) [31] 李卓, 宗燕兵, 张建良, 等. 高硅镁质熔剂性球团还原历程及冶金性能分析[J]. 钢铁, 2023, 58(3): 34. (LI Z, ZONG Y B, ZHANG J L, et al. Reduction process and metallurgical properties analysis of high silicon magnesia flux pellets[J]. Iron and Steel, 2023, 58(3): 34.) [32] 胡长庆, 王晓磊, 师学峰, 等. MgO及碱度对FeOx-SiO2-CaO-MgO-Al2O3体系液相生成的影响[J]. 钢铁, 2020, 55(4): 27. (HU C Q,WANG X L,SHI X F,et al. Effect of MgO and basicity on liquid phase formation of FeOx-SiO2-CaO-MgO-Al2O3 system[J]. Iron and Steel,2020, 55(4): 27.) [33] 王志星, 师学峰, 胡长庆, 等. MgO和Al2O3含量对铁酸钙生成的影响[J]. 钢铁钒钛, 2018, 39(6): 116. (WANG Z X, SHI X F, HU C Q, et al. Effects of MgO and Al2O3 on the formation of calcium ferrite[J]. Iron Steel Vanadium Titanium, 2018, 39(6): 116.) [34] 吕志义, 陈革, 马利, 等. 不同碱度及含氧化镁球团矿实验研究[J]. 包钢科技, 2003, 30(4): 1. (LÜ Z Y, CHEN G, MA L, et al. Experimental study on different basicity and different magnesia pellet[J]. Science and Technology of Baotou Steel, 2003, 30 (4): 1.)
2024, Vol. 59 
