Application of high-alumina type calcium ferrite: A new strategy of mineral phase regulation instead of chemical composition regulation in iron ore sintering

Abstract

High-alumina iron ores (Al₂O₃ content > 3.0wt%) are widely utilized in sinter production due to their economic benefits, yet their high alumina content challenges the performance of sinter and the stability of blast furnaces. This study focuses on the application of high-alumina composite calcium ferrites (SFCA) in the sintering of high-alumina iron ores. By prefabricating calcium ferrites, we aimed to substitute phase adjustment for compositional tuning, particularly examining its effects on enhancing sinter quality at 30wt%, 50wt%, and 100wt% replacement ratios of Al₂O₃. Previous work developed two types of high-alumina SFCA (A-type and B-type), with A-type demonstrating superior experimental performance. Our results indicate that increasing the proportion of A-type SFCA in the raw materials leads to higher calcium ferrite and composite calcium ferrite contents, while decreasing the proportions of Al₂O₃, CaO, SiO₂, calcium silicate, and calcium alumino-ferrite (CaAl_xFe_2−xO₄). Scanning electron microscopy (SEM) and mineralogical analyses reveal that sinter substituted with A-type SFCA primarily consists of SFCA and calcium ferraluminate (CFA), with increasing calcium ferrite content and decreasing porosity and silicate content as the substitution ratio increases. Complete substitution of Al₂O₃ with A-type SFCA enhances the compressive strength of the sinters to 22.57 MPa, a 6.76 MPa improvement over traditional methods. With 100wt% substitution, the reducibility reaches 0.85, a 0.33 increase over the baseline (A-type and B-type SFCA are not added). A cost-effective method for SFCA production using high-alumina ores, hazardous waste, and iron-calcium-based solid waste is proposed to lower production costs and promote the recycling of industrial solid waste. A-type SFCA exhibits significant advantages in mechanical properties, reducibility, and melting characteristics, validating its potential in optimizing sinter performance and reducing carbon emissions, thereby laying a theoretical and practical foundation for the industrial application of high-alumina SFCA.

Keywords

sintering / high alumina calcium ferrite / micro-morphology / carbon reduction / industrial preparation

References

[1] Archambo M, Kawatra SK. Red mud: Fundamentals and new avenues for utilization. Miner. Process. Extr. Metall. Rev.. 2021, 42(7): 427

[2] Upadhyay RK, Venkatesh AS. Current strategies and future challenges on exploration, beneficiation and value addition of iron ore resources with special emphasis on iron ores from eastern India. Appl. Earth Sci.. 2006, 115(4): 187

[3] Rao GV, Sharma SK. National steel policy: Challenges before iron ore producers. Trans. Indian Inst. Met.. 2016, 69(1): 107

[4] Zhu DQ, Xue YX, Pan J, et al. . Co-benefits of CO₂ emission reduction and sintering performance improvement of limonitic laterite via hot exhaust-gas recirculation sintering. Powder Technol.. 2020, 373: 727

[5] Y.X. Xue, J. Pan, D.Q Zhu, et al., Improving high-alumina iron ores processing via the investigation of the influence of alumina concentration and type on high-temperature characteristics, Minerals, 10(2020), No. 9, art. No. 802.

[6] ElDeeb AB, Brichkin VN, Kurtenkov RV, Bormotov IS. Extraction of alumina from Kaolin by a combination of pyro- and hydro-metallurgical processes. Appl. Clay Sci.. 2019, 172: 146

[7] Zhang GL, Fan ZX, Zhang X, Xu ZH, Meng Q. Asymmetric alumina-based ultrathin composite ceramic membranes with interfacial modification of black talc nanosheets. Ceram. Int.. 2023, 49(15): 25371

[8] Umadevi T, Deodar AV, Mahapatra PC, Prabhu M, Ranjan M. Influence of alumina on iron ore sinter properties and productivity in the conventional and selective granulation sintering process. Steel Res. Int.. 2009, 80(9): 686

[9] Li TL, Sun CY, Liu XY, Song S, Wang Q. The effects of MgO and Al₂O₃ behaviours on softening–melting properties of high basicity sinter. Ironmaking Steelmaking. 2018, 45(8): 755

[10] Zou Y, Huang A, Gu HZ, Zhang MJ, Lian PF. Effects of particle distribution of matrix on microstructure and slag resistance of lightweight Al₂O₃–MgO castables. Ceram. Int.. 2016, 42(1): 1964

[11] B.P. Sahoo, H.B. Sahu, and D.S. Pradhan, Hydrogeochemistry and surface water quality assessment of IB valley coalfield area, India, Appl. Water Sci., 11(2021), No.9, art. No. 153.

[12] S. Vögele, M. Grajewski, K. Govorukha, and D. Rübbelke, Challenges for the European steel industry: Analysis, possible consequences and impacts on sustainable development, Appl. Energy, 264(2020), art. No. 114633.

[13] Sabat KC. Hematite reduction by hydrogen plasma: Where are we now?. Int. J. Miner. Metall. Mater.. 2022, 29(10): 1932

[14] Nidheesh PV, Kumar MS. An overview of environmental sustainability in cement and steel production. J. Cleaner Prod.. 2019, 231: 856

[15] Yuan XY, Liu MD. Comprehensive utilization of high alumina iron ore resources. Mod. Min.. 2017, 33(2): 110

[16] Yu WT, Zuo HB, Zhang JL, Zhang T, et al. . Carpenter JS, Bai CG, Escobedo JP, et al. . The Effects of High Al₂O₃ on the Metallurgical Properties of Sinter. Characterization of Minerals, Metals, and Materials 2015. 2015, Cham, Springer: 419

[17] Wu Y. Effect of Al₂O₃ content of sinter on its properties. Res. Iron Steel. 2005, 33(6): 5

[18] R. Mežibrický, T. Csanádi, G. Habler, M. Fröhlichová, J. Dusza, and R. Abart, Synthesis and mechanical testing of calcium aluminosilicoferrite crystals with high alumina content, Metals, 9(2019), No. 8, art. No. 906.

[19] Ramanathan P, Baskar I, Muthupriya P, Venkatasubramani R. Performance of self-compacting concrete containing different mineral admixtures. KSCE J. Civ. Eng.. 2013, 17(2): 465

[20] Hou Y, Zhang S, Dang J, Guo J, Zhou HH, Lü XW. Viscosity and structure relationship with equimolar substitution of CaO with MgO in the CaO–MgO–Al₂O₃–SiO₂ slag melts. Int. J. Miner. Metall. Mater.. 2025, 32(1): 70

[21] Sanderson RA, Cann GM, Provis JL. The effect of blast-furnace slag particle size on the hydration of slag–Portland cement grouts at elevated temperatures. Adv. Cem. Res.. 2018, 30(8): 337

[22] H.M. Tang, Z.W. Peng, R. Tian, et al., Recycling of platinum-group metals from spent automotive catalysts by smelting, J. Environ. Chem. Eng., 10(2022), No. 6, art. No. 108709.

[23] Lü XW, Yan ZM, Pang ZD, Bai CG, Liang D, Xie H. Effect of Al₂O₃ on physicochemical properties and structure of blast furnace slag: Review. Iron Steel. 2020, 55(2): 1

[24] Jiang X, She FM, Han HS, Long F, Zheng HY, Gao QJ. Analysis and application of sectional control of w(MgO)/w(Al₂O₃) in blast furnace slag. Iron Steel. 2019, 54(10): 12

[25] Gupta S, French D, Sakurovs R, et al. . Minerals and iron-making reactions in blast furnaces. Prog. Energy Combust. Sci.. 2008, 34(2): 155

[26] Sarkar R, Sohn HY. Interaction of ferrous oxide with alumina refractory under flash ironmaking conditions. Ceram. Int.. 2019, 45(12): 15417

[27] Fernández-González D, Ruiz-Bustinza Í, Mochón J, González-Gasca C, Verdeja LF. Iron ore sintering: Process. Miner. Process. Extr. Metall. Rev.. 2017, 38(4): 215

[28] Pollock CJ. Great mining camps of Canada 6. Geology and history of the Wabana iron mines, Bell Island, Newfoundland. Geosci. Can.. 2019, 46(2): 69

[29] Liao JF, Zhao BJ. Phase equilibrium studies of titanomagnetite and ilmenite smelting slags. Int. J. Miner. Metall. Mater.. 2022, 29(12): 2162

[30] Zhao QC, Wang XH, Gong HL, Liu BB, Luo BC, Li LT. The properties of Al₂O₃ coated fine-grain temperature stable BaTiO₃-based ceramics sintered in reducing atmosphere. J. Am. Ceram. Soc.. 2018, 101(3): 1245

[31] Wang HY, Cao ZP, Wang JY, Wang ZR, Chen J, Shen LT. Alkali methods for alumina extraction from the byproducts of high alumina coal: A Review. Min. Metall. Explor.. 2023, 40(5): 1681

[32] Chang RD, Ding CY, Jiang F, et al. . High-alumina type calcium ferrite: A new mineral phase for low-carbon ironmaking in the future. Int. J. Miner. Metall. Mater.. 2025, 32(10): 2456

[33] Li G. Research on Sintering Technology of Vanadium Titanomagnetite with the Preformed Calcium Ferrite. 2022, Chongqing, Chongqing University: 138

[34] Guo J, Berbano SS, Guo HZ, Baker AL, Lanagan MT, Randall CA. Cold sintering process of composites: Bridging the processing temperature gap of ceramic and polymer materials. Adv. Funct. Mater.. 2016, 26(39): 7115

[35] Wang CW, Ping WW, Bai Q, et al. . A general method to synthesize and sinter bulk ceramics in seconds. Science. 2020, 368(6490): 521

[36] Guillon O, Gonzalez-Julian J, Dargatz B, et al. . Field-assisted sintering technology/spark plasma sintering: Mechanisms, materials, and technology developments. Adv. Eng. Mater.. 2014, 16(7): 830

[37] Munir ZA, Quach DV, Ohyanagi M. Electric current activation of sintering: a review of the pulsed electric current sintering process. J. Am. Ceram. Soc.. 2011, 94(1): 1

[38] Jenck JF, Frank A, Droescher MJ. Products and processes for a sustainable chemical industry: A review of achievements and prospects. Green Chem.. 2004, 6(11): 544

[39] J. Chapman, A.E. Ismail, and C.Z. Dinu, Industrial applications of enzymes: Recent advances, techniques, and outlooks, Catalysts, 8(2018), No. 6, art. No. 238.

[40] Arcadi A. Alternative synthetic methods through new developments in catalysis by gold. Chem. Rev.. 2008, 108(8): 3266

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