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The paper proposes a biomass cross-upgrading process that combines hydrothermal carbonization and pyrolysis to produce high-quality blast furnace injection fuel. The results showed that after upgrading, the volatile content of biochar ranged from 16.19% to 45.35%, and the alkali metal content, ash content, and specific surface area were significantly reduced. The optimal route for biochar production is hydrothermal carbonization–pyrolysis (P-HC), resulting in biochar with a higher calorific value, C=C structure, and increased graphitization degree. The apparent activation energy ( E ) of the sample ranges from 199.1 to 324.8 kJ/mol, with P-HC having an E of 277.8 kJ/mol, lower than that of raw biomass, primary biochar, and anthracite. This makes P-HC more suitable for blast furnace injection fuel. Additionally, the paper proposes a path for P-HC injection in blast furnaces and calculates potential environmental benefits. P-HC offers the highest potential for carbon emission reduction, capable of reducing emissions by 96.04 kg/t when replacing 40wt% coal injection.

N,N-dimethylformamide’s (DMF) participation in domino reactions has been developed. Starting from substituted halogenobenzenes and selenium powder, versatile biologically active Se-phenyl dimethylcarbamoselenoate derivatives were efficiently synthesized under mild reaction conditions. The reaction mechanism was studied using control experiments. These protocols involve a wider substrate scope and provide an economical approach toward C–selenium bond formation.

The use of magnetite-based iron ore fines by means of fluidized bed technology has become a promising route to produce direct reduced iron. The significant influence of a prior oxidation treatment, which occurs in the preheating stage, on the subsequent fluidization and reduction behavior was observed in our previous study. As a result, it is important to investigate the oxidation of magnetite-based iron ore fines for an optimization of the proposed route. Three magnetite-based iron ore brands were analyzed. The oxidation characteristics are investigated based on thermogravimetric analysis. The surface morphology, structural evolution, and phase transformation were studied with a scanning electron microscope, an optical light microscope, and a high-temperature-X-ray diffraction (HT-XRD), respectively. The three samples showed different oxidation capacity indexes (OCIs) but similar TG-DTG curves. The oxidation rate peaks at around 330 °C and 550 °C indicated the formation of γ-Fe2O3 and α-Fe2O3. The hematite phase shows a particular growth habit. The oxidation first occurs at the surface, forming gridlike hematite structures, and then extends to the inside, resulting in hematite needles. The specific surface area and pore volume decrease significantly due to the sintering effect during oxidation.

Magnetite-based iron ore usually shows a high sticking tendency and a poor reducibility in the fluidized bed because of its dense structure. To enhance the fluidization and reduction behaviors of magnetite-based iron ore during hydrogen-induced fluidized bed reduction, the effect of a prior oxidation treatment is investigated. The results show that the untreated magnetite-based iron ore cannot be fluidized successfully in the tested temperature range between 600 °C and 800 °C. At 600 °C reduction temperature, the de-fluidization can be avoided by a prior oxidation treatment. At higher reduction temperatures, the fluidization behavior can be further improved by an addition of 0.5 wt pct MgO. Magnesiowüstite (FexMg1−xO) is formed, which decreases the contact chance of the sticky surface between particles. Regarding to the reduction rate, a prior partial oxidation is more beneficial compared to deep oxidation. The kinetic analysis shows that MgO could promote the initial reaction. The reaction rate limiting step is no longer diffusion but chemical reaction for prior partly oxidized samples. A prior partial oxidation combined with an addition of MgO is considered to be a promising pretreatment method for a successful processing of magnetite-based iron ore.

This study evaluated how raw-material compounding strategies affect the high-temperature compressive strength of ferro-coke. Ferro-coke was prepared using varying additions of iron-carbon-containing dust (ICD) and different gasification temperatures. High-temperature experiments were conducted to study the reactivity (CRI) and hot strength of ferro-coke, and fracture morphologies were examined by microscopy and Micro-CT. The results show that both the increase in ICD addition amount and gasification temperature would increase the reactivity and decrease the high temperature of ferro-coke. As ICD addition increased from 5% to 20%, the reactivity of the ferro-coke rose from 58.70% to 76.32%, and high-temperature strength decreased from 3260 N to 1954 N at 800 °C. This trend is attributed to catalytic components in ICD (e.g., Fe, Zn), which would accelerate gasification, increase porosity, and reduce high-temperature strength. Similarly, increasing the gasification temperature from 1000 °C to 1200 °C enhanced reactivity from 51.95% to 65.51%, but the hot strength was reduced. The higher carbon gasification rate at elevated temperature increases porosity and weakens the coke matrix, lowering compressive strength.

The utilization of iron coke provides a green pathway for low-carbon ironmaking. To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification, the effect of iron ore on the microstructure of iron coke was investigated. Furthermore, a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric method. The findings indicate that compared to coke, iron coke exhibits an augmentation in micropores and specific surface area, and the micropores further extend and interconnect. This provides more adsorption sites for CO 2 molecules during the gasification process, resulting in a reduction in the initial gasification temperature of iron coke. Accelerating the heating rate in non-isothermal gasification can enhance the reactivity of iron coke. The metallic iron reduced from iron ore is embedded in the carbon matrix, reducing the orderliness of the carbon structure, which is primarily responsible for the heightened reactivity of the carbon atoms. The kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore structure. Moreover, as the proportion of iron ore increases, the activation energy for the carbon gasification gradually decreases, from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.

Al2O3 greatly influences the formation of complex calcium ferrite, which is the main binder and iron-bearing phase in sinter. Experiments were carried out in air at 1200 °C with different amounts of Al2O3 mixed with CaO·Fe2O3 (calcium ferrite). The samples contained two phases: CaFe2O4 and Ca3.18Fe15.38Al1.34O28 (CFA). The results showed that the morphology of the complex calcium ferrite was massive (w(Al2O3) = 0 pct), columnar and plate-like (w(Al2O3) = 0.5 and 1 pct), and acicular and plate-like (w(Al2O3) = 2, 3, and 5 pct). A small amount of Al2O3 solid solution in CaFe2O4 increased the preferred orientation of the crystal. The gradual increase in Al2O3 in the sintered samples caused the complex calcium ferrite composition to be closer to that of silico-ferrite of calcium and aluminum (acicular SFCA-I). When Al2O3 dissolved into calcium ferrite, complex calcium ferrite was formed, which increased the hardness of the sample. The fracture toughness of the sample increased with increasing Al2O3 content from 0 to 2 pct, possibly due to a decrease in grain size. When the Al2O3 content exceeded 3 pct, Al2O3 dissolved into calcium ferrite and decreased the fracture toughness of the sample.

Oxygen blast furnace is an important transformation method for the low-carbon and green development of traditional blast furnaces. This paper establishes a multi-zone mass and heat balance model and computational fluid dynamics model to study the influence of different hydrogen-rich gas composition on the smelting parameters, raceway state and combustion behavior of oxygen blast furnaces. The results show that the higher gas injection temperature can increase its physical heat, thereby reducing the coke ratio and improving the gas utilization rate. Furthermore, the injection amount of CH 4 and H 2 increases, resulting in lower raceway temperature and the direct reduction degree in the furnace, which can still meet the smelting requirements at lower raceway temperatures in actual production. Meanwhile, due to the oxygen competition relationship between coal and hydrogen-rich gas, as the proportion of CH 4 and H 2 injection increases, the coal burnout rate decreases. This research provides a theoretical basis for the regulation of low-carbon and high-efficiency oxygen blast furnace gas injection components.

Ferro-coke is prepared by the slight coking of coal and iron ore. It is a new type of fuel used for blast furnace ironmaking for the purpose of energy saving and emission reduction. However, with the increase of iron ore content, the metallurgical properties of ferro-coke gradually deteriorate. To fabricate high-strength ferro-coke, coal tar pitch was used as a binder in this study. The microstructure, cold drum strength, thermal crushing strength, gasification reactivity and gasification kinetics of this modified ferro-coke were systematically studied and compared with those of gas-coal coke and ferro-coke without binder. The results showed that the coal tar pitch could reduce the porosity of ferro-coke by 4.57 pct, enhance the adhesion of carbon matrix to minerals and increase the microcrystalline structure of ferro-coke. The cold drum strength of ferro-coke increased from 28.04 to 86.34 pct after adding coal tar pitch, while the thermal strength of ferro-coke during the gasification process rose by only 100 N. The coal tar pitch had little effect on the gasification reactivity of ferro-coke, so the activation energy of modified ferro-coke was still low. The first-principle calculation results revealed that the promotion of Fe on the ferro-coke gasification was attributed to the reducing role of Fe on the reaction energy of ketone group decomposition.

Exploring appropriate carbonisation process parameters is important for optimising the recycling of waste bamboo chopsticks as an alternative solid fuel for traditional ironmaking. The purpose of this research was to reveal the influence of the pyrolysis temperature on the structural features and combustion behaviour of waste bamboo chopstick chars. The fixed carbon content of waste bamboo chopstick chars increased from 46.57% to 82.83% and the volatile content decreased from 56.43% to 6.86% with pyrolysis temperature increasing from 573 to 973 K. At the same time, the O/C and H/C values gradually decreased from 0.23 to 0.08 and from 0.05 to 0.02, respectively. The surface area of waste bamboo chopstick chars first increased sharply from 2.15 m2/g at 773 K to 11.04 m2/g at 873 K, and then decreased to 1.96 m2/g at 973 K. The combustion behaviour had a close relationship with the pore structure of waste bamboo chopstick chars, and the best combustion properties were exhibited at a pyrolysis temperature of 873 K. It was found that volumetric model was the most suitable model for describing the combustion process of waste bamboo chopstick chars pyrolysed below 673 K, while random pore model was the best one for the chars pyrolysed above 673 K. The combustion activation energies of the waste bamboo chopstick chars ranged from 116.89 to 156.07 kJ/mol. There was an obvious kinetic compensation effect during the combustion.