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• Injection parameters of H 2 -rich gas over sintering process were optimized. • Experiment and numerical simulation were used to elucidate function mechanism. • A novel method on hydrogen-rich energy application in practical plants was developed. H 2 -rich gas has been widely regarded as a promising energy to substitute fossil energy in iron ore sintering process for CO 2 reduction. This investigation mainly focused on researching the influences of H 2 -rich gas injection parameters over sintering bed on sintering performance, and elucidated the potential function mechanism through both experiment and numerical simulation. Results indicated that increasing injection concentration and prolonging injection time within a proper range improved sinter quality, and the recommended value was 0.6∼0.8 % and 8 min, respectively. Injecting H 2 -rich gas at earlier sintering stages achieved greater improvement in sintering quality compared with the ones injecting at later sintering stages, and the recommended injection area was 5∼13min. Both experiment and numerical simulation results indicated that injecting H 2 -rich improved the thermal patterns of sintering bed, with extended high-temperature areas for increasing the generation of high-strength calcium ferrite. Especially when injecting H 2 -rich gas under the recommended parameters, the heat distribution in sintering bed was optimized and the sintering quality of upper sintering layer was obviously improved. Finally, an injection method for guiding the industrial application with its essence to inject H 2 -rich at earlier sintering stages was proposed. The research findings provide a promising way for the efficient utilization of clean energy in iron ore sintering plants. [ABSTRACT FROM AUTHOR]

Surface ignition is the first and also the important step for iron ore sintering, which provides the initial source of energy to trigger the whole reactions. This investigation mainly focused on revealing the relationship between surface ignition and sintering performance, and elucidated the deep mechanism. Results indicate that the quality of sinter in the surface layer can be effectively improved by adjusting the ignition parameters. The preferred ignition parameters include ignition temperature of 1050 °C, ignition duration of 1 min and heat preservation of 1−2 min. The function mechanism of improved sinter quality is attributed to the increased high temperature duration for minerals melting, the enlarged melting zone, and the decreased cooling velocity. These changes facilitate the formation of enough adhesive phase of calcium ferrite, more of which generated in acicular morphology with high mechanical strength. Optimizing the ignition process reduced the solid fuel consumption due to the improved sintering performance, which then decreased the emission of NO and SO 2. The research findings are of great significance for providing a guide for the design of desirable ignition system and making further contributions to energy conservation and emission reduction during sintering. [ABSTRACT FROM AUTHOR]

Hydrogen-rich gas and steam are widely regarded to be of great potential to mitigate CO 2 emissions in iron ore sintering, these gases can regulate heat distribution in the sintering machines by replacing fossil fuels. However, most sintering machines only use one of the gases as the injecting medium, the potential of this technology has not been developed. In this paper, a multiple gaseous medium injection method contained natural gas and steam was experimentally investigated to solving this problem. Sintering tests were arranged to study the appropriate scheme of coupling injection and its influence on the sintering process, and the flue gas analyzer was used to detect the composition of the sintering flue gas in real time. Better sintering indexes were achieved by injecting the above two gaseous medium when the coke breeze ratio is unchanged, the results show that when 0.8 vol% natural gas is injected into the 4–14min, 0.15 vol% steam is injected into the 10–14 min, and 0.25 vol% steam is injected into the 15–18 min of sintering, the sintering yield increases by 2.42%, and the tumbler index increases by 2.72%. Under the above parameters, the coke breeze ratio can be reduced by 12.99%, the average NOx emissions decreased by 19.5%, and the average CO emissions decreased by 36.96% in the coupling injection interval (4–18min). After calculating the amount of coke breeze and natural gas in the optimal coupling injection sintering, CO 2 emissions decreased by 7.66%, about 17.15 kg/t -sinter. Moreover, the PFR model was used to simulate the associated gas phase reaction after coupling injection which shows H 2 O significantly reduced CO emissions and change the reduction pathway of NO. Generally, sintering fuel consumption and greenhouse gas emissions have also been reduced, providing theoretical support for the change of iron ore sintering energy structure. [Display omitted] • Natural gas and steam coupling injection in iron ore sintering for the first time. • The energy structure is optimized to partial replace fossil fuel with gas-based fuel. • The heat distribution and sintering speed after coupling injecting are analyzed. • PFR model shows the NO reduction pathway will change when steam is present. • CO 2 emission can be reduced by 91400 t/year with coupling injection sintering. [ABSTRACT FROM AUTHOR]