No abstract

Gasification reaction behavior of iron coke as well as kinetic parameters is extremely important for its quality evaluation and practical application in an actual blast furnace. However, there are few researches on the gasification behavior of iron coke, especially for iron coke hot briquette (ICHB) prepared by hot briquetting process. In this paper, the gasification reaction behavior of ICHB is experimentally investigated under isothermal conditions. Meanwhile, the kinetic analysis for the gasification process of ICHB and the related mechanism are carried out. The results demonstrate that the increase of the reaction temperature causes the significant rise of the carbon conversion rate and the reaction rate of ICHB, while the post‐reaction strength is evidently decreased. The size degradation of ICHB after reaction is increasingly serious as the reaction temperature goes up, and more pores as well as cracks are generated inside the gasified ICHB. During the gasification, the reduction of iron oxide, the oxidization of metal iron, and the generation reaction of fayalite are concomitantly occurred. The most probable mechanism function is confirmed. Based on this model, the activation energy and pre‐exponential factor are conducted, which are 144.77 kJ mol−1 and 999.37 min−1, respectively.

Utilization of iron carbon agglomerates (ICA) with high reactivity in blast furnace (BF) can reduce fuel ratio and carbon emission by decreasing the temperature of thermal reserve zone, which is considered to be an innovative technology for achieving low-carbon ironmaking. Herein, the influences of coal tar pitch (CTP) as binder on the metallurgical properties of ICA are investigated. The results show that the compressive strength of ICA is first enhanced from 1639 to 3168 N and then reduced to 2243 N with the ratio of CTP increasing from 0% to 11%. Meanwhile, the drum strength (I 600 10 ) of ICA is accelerated from 67.3% to 80.5% and then leveled off. In addition, the reactivity of ICA is mitigated from 65.6% to 58.1% first and then increased to 68.8%, while the post-reaction strength shows an inverse trend. When the ratio of CTP is 5-7%, the mechanical strength, reactivity, and post-reaction of ICA are all at a relatively better levels. For the ICA with adding CTP, the mechanical strength is dependent on the microstructure, pore volume, and specific surface area, whereas the variation of reactivity and post-reaction strength are relevant to the pore structure and carbon crystallites structure.

No abstract

No abstract

Research data are not shared.

The effect of iron carbon agglomerates (ICA) on the reduction of pellet (or sinter) is very important to the smelting efficiency of BF. In this paper, the effect of addition amount of ICA on the reduction of pellets and the isothermal reduction reaction kinetics of pellets-ICA mixture were comprehensively studied. The results show that the addition of ICA among pellets can significantly improve the reduction degree of pellets. There is a synergistic effect between ICA and pellets. All the pellets-ICA mixtures have the same reaction control mechanism: stage 1 is the secondary order chemical reaction F2, and stage 2 is the phase boundary reaction R2 of shrinking core model. As the amount of ICA increases from 15 to 35%, the activation energy of pellets-ICA mixture at stage 1 decreases from 95.53 to 75.21 kJ/mol, and the activation energy at stage 2 increases from 98.18 to 138.34 kJ/mol.

Iron and steel are one of the most important industrial raw materials, and are thus considered as a pillar of the Chinese economy. [1,2] The iron and steel industries play an important role in the national economy of China and are the foundation of its rapid industrialization and urbanization. [3] Steel production and consumption in China were 996.63 and 945.27 million tons in 2019, accounting for 53% and 50% of the world's total steel production and consumption, respectively. [4] However, iron and steel production are one of the most energy-and carbon-intensive processes in the world, and they account for more than 5% of the world's annual energy demand. [5][6][7] It is well known that carbon dioxide emission contributes to climate change and is likely to have an adverse effect on human health. [8] China has proposed the goal of achieving carbon emissions peak by 2030 and will strive to be carbon neutral by 2060. [9] Driven by the carbon neutrality target, a rapid and far-reaching clean iron and steelmaking process is expected. At present, the most common iron and steelmaking process involves a long process, named blast furnace-basic oxygen furnace (BF-BOF), which accounts for 90% of China's steel production and is emissionintensive, mainly owing to its reliance on coal. [4] In the presently used iron and steel production processes, energy consumption and CO 2 emissions mainly derive from the ironmaking process. Therefore, decreasing CO 2 emissions and reducing the energy consumption of the blast furnace used in ironmaking are of great importance for the sustainable development of the steel industry in China. [10] In the long term, hydrogen metallurgy has great potential due to its low-carbon emission levels and high efficiency for iron and steelmaking processes. However, the high cost of green hydrogen production has made it difficult for China to absolutely adopt this process. Above all, decreasing carbon emissions and energy consumption through the update of present BF-BOF processes has important practical implications. In recent years, iron coke has become one of the most popular research directions for low-carbon ironmaking in blast furnaces. [11][12][13][14][15][16] Iron coke, which is also named as ferro coke and iron carbon agglomerates, is one of several innovative highly reactive cokes used as blast furnace burdens. Iron coke is helpful for energy saving, CO 2 emissions reduction, and green production of iron in the ironmaking process because it uses cheap coal resources, is highly reactive in the reduction process (in relation to the reaction rate of coke with CO 2 ), and decreases the thermal reserve zone temperature of the blast furnace. [17][18][19][20] In the iron coke carbonization process, approximately 70% of iron oxides in the iron ore powder added to coal are reduced to metallic iron. [21] Metallic iron helps decrease the starting temperature for gasification because it has a catalytic effect on the gasification process. [22] Besides, the number of pores in iron coke is greater