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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.

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Metallurgical coke is an important raw material for blast furnaces. Specifically, temperature and CO2 significantly affect its metallurgical behavior. In this study, the influence of temperature and CO2 on the high-temperature behavior of three metallurgical coke samples, used in blast furnaces of different volumes, was investigated. The carbon structure and pore structure of the coke samples were analyzed. The results indicated that as the temperature increased from 1100 to 1500 °C, the weight loss ratio increased 10-fold and the drum strength decreased to approximately 80% in Ar. Under a CO2 atmosphere, as the temperature increased from 1100 to 1300 °C, the reactivity index increased from 20 to 70%, and the strength after reaction exhibited the lowest value of 40% at 1250 °C. When the temperature increased from 1100 to 1500 °C, the stacking height of the layer structure Lc of the coke samples increased to ∼5.5 nm. Under the influence of CO2 and temperature, the Lc of the coke samples increased to approximately 4 nm between 1100 and 1300 °C. Furthermore, CO2 slightly affected the carbon structure. The changes in pores under the influence of CO2 and temperature were greater than those under the influence of temperature between 1100 and 1300 °C. Typically, the strength of coke is high when the pore number, roundness, and porosity are low. The strength and microstructure parameters of the coke samples were correlated via multiple regression. The results of the multiple regression showed that the carbon structure and pore number had the highest impact on coke strength, followed by roundness and porosity.

Steel slag is a dense and rock-like byproduct of the steel production process. In China, more than 100 million tons of steel slag is produced each year. [1,2] However, only about 30% of the steel slag is utilized availably. [3,4] The main chemical components of steel slag are calcium oxide (CaO), ferrous oxide (FeO), magnesium oxide (MgO), and silicon dioxide (SiO 2 ). Currently, steel slag is widely used in various fields, such as coarse aggregates in roads and pavements and hydraulic engineering, fine aggregates in concrete, and supplementary cementation materials in blended cement. [5][6][7][8] In contrast, global warming has aroused continuous and widespread concern. CO 2 is the main greenhouse gas resulting in global warming, which is harmful to the balance of the natural ecosystem. [9] In 2019, the CO 2 emissions of China, the United States, Europe, and India were 9809.2, 4766.4, 3995.2, and 2309.1 Mt, respectively. [10] The total CO 2 emission of China accounts for more than 28% of the global total CO 2 output, far higher than other countries. [11] Moreover, China's iron and steel industry emits about 16.02% of the CO 2 produced by the global steel industry, which is one of the largest CO 2 emitters of industry. [12][13][14] Thus, how to effectively reduce CO 2 emission for the iron and steel industry has attracted significant interest. [15][16][17] Effective measures should be made to decrease CO 2 emissions for the iron and steel industry. The long process of blast furnacebasic oxygen furnace is the main process of the Chinese steel industry, accounting for more than 90% of China's crude steel production. [18] Blast furnace ironmaking accounts for over 70% of the energy consumption and about 80% of the CO 2 emission of the whole steel production process. [19] Therefore, blast furnace ironmaking is the key to energy saving and emission reduction in the iron and steel industry.To reduce the CO 2 emissions of the iron and steel industry, some low-carbon blast furnace technologies have been put forward or applied in practice. [20][21][22] Under these circumstances, some studies show that applying composite iron coke to blast furnaces could make the thermal reserve temperature drop, strengthen reduction in furnace, improve smelting efficiency, decrease coke ratio, and finally reduce CO 2 emission. [23][24][25][26] With using composite iron coke instead of 30% coke

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