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The high-temperature zone of the sintering bed is the crucial area for material change and structural remodeling, and the heat is provided by coke combustion. Understanding how fuel combustion affects bed structure is of great significance to optimize sintering parameters and sintering quality. In this study, sintering pot tests were carried out under three coke ratios of 4.5%, 5.0% and 5.5%, and liquid nitrogen was used to quench the high-temperature zone sintering. The clear internal structure of the high-temperature zone sinter was obtained using X-ray computed tomography (XCT). Results show that with the increase of coke ratio, the porosity in the high-temperature zone decreases from 54.29% to 51.04% and 48.07%, and the number of terminal nodes, branch nodes and segments of the pore skeleton decreases by 51.6%, 55.2% and 53.1% respectively. The pores in the high-temperature zone are fully fused and developed. • Liquid nitrogen was used to quench the high-temperature zone of the sinter. • The structure of high-temperature zone was reconstructed completely with X-ray computed tomography. • The quantitative and morphological characteristics of pores were deeply analyzed. • The increase of coke ratio promotes the remodeling of sintering bed structure. [ABSTRACT FROM AUTHOR]

Using a clean fuel produced by electrolysis named Brown gas to assist sintering in the iron ore sintering process was proposed to reduce coke consumption and carbon emissions. The effect of additional injection of Brown gas on the combustion characteristics and the quality of the sintered ore were explored. An optimal fuel ratio was investigated by gradually reducing the coke ratio based on Brown gas injection. The experimental results show that additional injection of Brown gas improves the thermal mode of the sintering bed, improves fuel combustion efficiency, prolongs the duration time of melting temperature, and the sintered ore yield and shatter strength first increases and then decreases, reaching the maximum value at an injection concentration of 2%. Based on a Brown gas injection concentration of 2%, the coke ratio can be reduced from 4.5% to 4% without affecting the quality of the sintered ore. As the coke ratio further decreases to 3.5%, the quality of the sintered ore deteriorates even if the Brown gas injection concentration increases to 3%. Based on a 2% Brown gas injection, the consumption of coke can be reduced by 11.1%, and the carbon emissions during the sintering process can be reduced by 11.1%. • The feasibility of a clean fuel named Brown gas to assist in sintering was verified. • Brown gas injection improves fuel combustion efficiency and sintered ore quality. • The optimal Brown gas additional injection concentration is 2% vol. • The coke consumption can reduce by 11.1% based on a 2% Brown gas injection. [ABSTRACT FROM AUTHOR]

• Ammonia injection significantly improves fuel combustion efficiency. • Inject ammonia in the early sintering stage is more conducive to improving the sinter ore yield and strength. • Ammonia segregation injection improves the heat distribution uniformity of the sintering bed. • The optimal segregation degree for ammonia injection is 0.042%/min. To reduce solid fuel consumption and carbon emissions during iron ore sintering, ammonia injection-assisted sintering was proposed, and its feasibility was verified through sinter pot experiments. The effects of ammonia injection stages and segregation degrees on the sintering characteristics were investigated based on the uneven heat distribution in the sintering bed. The results show that ammonia injection improves fuel combustion efficiency, sinter bed temperature and melting quantity index. The sinter ore strength and yield were improved, and the effect of injecting ammonia in the early sintering stage was more significant. When the ammonia injection segregation degree is 0.042 %/min, the sinter ore yield and tumbler index increase from 61.93% and 49.4% to 68.85% and 58.8%, respectively, the average fuel combustion efficiency increases from 89.02% to 92.30%. When the segregation degree increases from 0 to 0.125 %/min, the standard deviation of the uniformity coefficient of the high-temperature index first decreases and then increases, reaching the minimum value when the segregation degree is 0.042 %/min. A segregation degree of 0.042 %/min can achieve the most uniform heat distribution in the sintering bed and the best sinter ore quality, which provides a reference for applying ammonia injection-assisted sintering in industrial production. [ABSTRACT FROM AUTHOR]

A divided fuel addition method combining coke and biochar was proposed to optimize the fuel distribution in the iron ore sintering process. The combustion behavior of biochar and sinter quality is improved by increasing the proportion of coke in the upper layer and the substitution proportion of biochar in the lower layer. Results show that the duration time of melting temperature and melting quantity index of the upper and lower layers after divided fuel addition is significantly higher than those without delamination. The sinter yield and tumbler index significantly increased from 55.26% and 50.37% to 65.61% and 56.47% when the biochar substitution ratio was 50%. The comprehensive sintering index shows that the appropriate replacement proportion of biochar can be increased from 40% to 50% by dividing fuel addition. The maximum replacement ratio of biochar increased by 25%, significantly reducing coke consumption and carbon emissions during the iron ore sintering process. • A divided fuel addition method combining coke and biochar was proposed to optimize the fuel distribution. • The thermal characteristics of the upper and lower layers are compared. • The sinter quality significantly improved by dividing fuel addition. • The appropriate replacement proportion of biochar can be increased from 40% to 50% by dividing fuel addition. [ABSTRACT FROM AUTHOR]