Experimental Study on the Strength Distribution and Pore Distribution of Industrial Pellet and DRI

Abstract

Against the backdrop of the “dual-carbon” goals driving the steel industry's transition toward hydrogen metallurgy, the hydrogen-based shaft furnace process has emerged as a focal point due to its low-carbon emissions. This study employs compression testing, mercury intrusion porosimeter, and industrial computed tomography characterization to compare the mechanical properties and pore structures of industrial pellets and direct reduced iron (DRI). The results show that the compressive strength and mass specific breakage energy of DRI are lower than those of pellets, and the breakage characteristic parameters at the same particle size are lower, making it more prone to breakage; the compressive strength of both increases with the increase of particle size, the mass specific breakage energy decreases with the increase of particle size, and the strength growth rate of pellets is faster. In terms of pore structure, pellets are mainly composed of uniform macropores of 3428 nm with a porosity of 22.3%; DRI has a porosity of 48.8%, mainly composed of 3431 nm macropores and 831 nm micropores, with a low tortuosity index, which is conducive to gas diffusion. This study provides parameters and theoretical basis for modeling of burden movement and crushing in shaft furnace.

Keywords

Ironmaking / Pellet / DRI / Compressive strength / Breakage energy / Porosity

Acknowledgement

The authors gratefully acknowledge the financial support provided by the National Natural Science Foundation of China (52374319), the Young Elite Scientists Sponsorship Program by CAST (NO. YESS20230029), the National Youth Talent Support Program (GJRC2023008), the National Natural Science Foundation of China (52204335), the National Natural Science Foundation of China (52174291).

Author Contributions

Z.L.: Project administration, Funding acquisition, Conceptualization. S.L.: Writing—original draft, Methodology, Formal analysis. Y.W.: Writing—review & editing, Funding acquisition. J.Z.: Supervision, Investigation.

Ethics Statement

Not applicable.

Informed Consent Statement

Not applicable.

5Data Availability Statement

Data will be made available on request.

Data Availability Statement

Data will be made available on request.

Funding

This research was funded by the National Natural Science Foundation of China (52374319), the Young Elite Scientists Sponsorship Program by CAST (NO. YESS20230029), the National Youth Talent Support Program (GJRC2023008), the National Natural Science Foundation of China (52204335), the National Natural Science Foundation of China (52174291).

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

References

[1] Holappa L. A general vision for reduction of energy consumption and CO 2 emissions from the steel industry. Metals 2020, 10, 1117.

[2] Flores-Granobles M, Saeys M. Minimizing CO₂ emissions with renewable energy: a comparative study of emerging technologies in the steel industry. Energy Environ. Sci. 2020, 13, 1923-1932.

[3] Rechberger K, Spanlang A, Sasiain Conde A, Wolfmeir H, Harris C. Green hydrogen‐based direct reduction for low‐carbon steelmaking. Steel Res Int. 2020, 91, 2000110.

[4] Duarte PE, Becerra J. Reducing greenhouse gas emissions with Energiron non-selective carbon-free emissions scheme. Stahl und Eisen: Zeitschrift fuer die Herstellung und Verarbeitung von Eisen und Stahl 2011, 131, 85.

[5] Wagner D.Etude expérimentale et modélisation de la réduction du minerai de fer par l’hydrogène. PhD dissertation, Institut National Polytechnique de Lorraine-INPL, Nancy, France, 2008.

[6] Lan C, Sun Q, Wang X, Liu C, Zhang W, Li Y, et al. Metallurgical properties evolution of coke oven gas zero reforming reduction pellet. Iron Steel 2024, 59, 1-16.

[7] Barrios GKP, De Carvalho RM, Kwade A, Tavares LM. Contact parameter estimation for DEM simulation of iron ore pellet handling. Powder Technol. 2013, 248, 84-93.

[8] Barrios GKP, Jiménez-Herrera N, Tavares LM. Simulation of particle bed breakage by slow compression and impact using a DEM particle replacement model. Adv. Powder Technol. 2020, 31, 2749-2758.

[9] Tavares LM, Cavalcanti PP, De Carvalho RM, da Silveira MW, Bianchi M, Otaviano M. Fracture probability and fragment size distribution of fired Iron ore pellets by impact. Powder Technol. 2018, 336, 546-554.

[10] Cavalcanti PP, Petit HA, Thomazini AD, de Carvalho RM, Tavares LM. Modeling of degradation by impact of individual iron ore pellets. Powder Technol. 2021, 378, 795-807.

[11] Boechat FO, De Carvalho RM, Tavares LM. Simulation of mechanical degradation of iron ore pellets in a direct reduction furnace. KONA Powder Particle J. 2018, 35, 216-225.

[12] Cavalcanti PPS. Calibration and Validation of a Mathematical Model of Degradation of Fired Pellets during Transportation and Handling. Master’s thesis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil, 2015.

[13] Boechat FO, Rocha LTD, Carvalho RMD, Jung SM, Tavares LM. Amenability of Reduced Iron Ore Pellets to Mechanical Degradation. ISIJ Int. 2018, 58, 1028-1033.

[14] Petit HA, Boechat FO, De Carvalho RM, Tavares LM. Analysis of impact of mechanical degradation of iron ore pellets on gas flow in a direct reduction furnace using simulation. J. Mat. Res. Technol. 2024, 28, 4540-4550.

[15] Tavares LM, De Carvalho RM. Modeling breakage rates of coarse particles in ball mills. Miner. Eng. 2009, 22, 650-659.

[16] Tavares L. Optimum routes for particle breakage by impact. Powder Technol. 2004, 142, 81-91.

[17] Zhou Q, Pan Y, Zhu C, Wei Y, Yao F, Liu Z. Experimental study on strength distribution of brittle materials at quasistatic state. J. China Coal Soc. 2019, 44, 708-716.

[18] Kim G, Pistorius PC. Strength of direct reduced iron following gas-based reduction and carburization. Metallurg. Mat. Transact. B 2020, 51, 2628-2641.

[19] Deng X-J, Zuo H-B, Xue Q-G, Xue QG, Wang JS. Research on the reaction behavior of pellets in typical atmospheres of shaft furnaces: Reduction swelling and carbon deposition. Powder Technol. 2024, 438, 119629.

[20] Huang Z, Yi L, Jiang T. Mechanisms of strength decrease in the initial reduction of iron ore oxide pellets. Powder Technol. 2012, 221, 284-291.

[21] Kovtun O, Levchenko M, Oldinski E, Gräbner M, Volkova O. Swelling Behavior of Iron Ore Pellets during Reduction in H2 and N2/H 2 Atmospheres at Different Temperatures. Steel Res. Int. 2023, 94, 2300140.

[22] Yang J, Li L, Liang Z, Peng X, Deng X, Li J, et al. Direct reduction of iron ore pellets by H2-CO mixture: An in-situ investigation of the evolution and dynamics of swelling. Mat. Today Commun. 2023, 36, 106940.

[23] Xu C, Zhang J, Liu Z, Wang Y, Li Z, Ma L. A Comprehensive Study of Pore Characteristics, Formation Mechanism and Reliability Analysis with Advanced Characterization Methods Within Pellets. Transact. Indian Inst. Met. 2020, 73, 2503-2510.

[24] Tavares JHR, Da Luz JM, Ribeiro FF. Weathering impacts on iron ore pellets. Caderno Pedagógico 2025, 22, e16669-e16669.