The production of furfural and xylose from corn cob hydrolysis generates significant residues. Utilizing these residues in blast furnace (BF) injection could reduce costs and fossil CO<inf>2</inf> emissions in the ironmaking process. This study analyzed the physicochemical and combustion behaviors of hydrolyzed corn cob residues from six biomass chemical enterprises. The residues mainly contain cellulose and lignin, resulting in high volatile matter, low fixed carbon, and energy density. They retain a loose, porous structure with oxygen-rich surfaces, enhancing combustion performance. However, high alkali metal content limits their BF injection application. Combustion kinetics revealed a two-stage process corresponding to cellulose and lignin combustion, with activation energies ranging from 24.6 to 53.3 kJ/mol for cellulose and 8.8–27.3 kJ/mol for lignin. Increasing heating rates elevate activation energies due to enhanced molecular motion and reaction participation. These insights provide valuable guidance for integrating biomass waste into ironmaking, supporting cost reduction and carbon neutrality in the steel industry. Replacing 30 % of the daily injection agent in a medium-sized blast furnace with corn cob hydrolyzed residue can reduce fuel costs by approximately 30 %, equivalent to savings of about RMB 10 per ton of hot iron. For a steel plant with an annual output of 3 million tons, this translates to annual savings of approximately RMB 10–15 million.

The disposal of pharmaceutical sludge (PS) involves relatively high technical risks. This study explores the hydrothermal carbonization (HTC) process for converting PS into valuable carbonaceous materials. By varying the temperature and holding time of HTC, the carbonaceous structure of the products, the migration and transformation behavior of metals, the fuel properties, as well as the reaction mechanism were analyzed. The results indicate that with the increase in holding time, volatile matter content decreases while ash content increases. As temperature rises, volatile matter also decreases, accompanied by an increase in ash content. Holding time has a minimal impact on the role of Fe in promoting the HTC process, whereas temperature exerts a more significant effect. The change in Zn content is slight when holding time varies, and it reaches its maximum when the temperature reaches 215 degrees C. Longer holding time and higher temperature reduce C=C and C-O bonds, while enhancing aromatization and graphitization, resulting in a more stable coal-like structure similar to lignite. Overall, HTC effectively modifies the physicochemical properties of PS, which holds great significance for the resource recovery of PS.

To tackle global energy and environmental challenges, address the unclear gasification mechanism of lignin in CO2/H2O environments, this study uses reactive molecular dynamics simulations to investigate lignin gasification rules and mechanisms. A lignin system was simulated across a temperature gradient of 2000-3500 K via LAMMPS to elucidate molecular evolution, solid-liquid-gas phase transitions, and intrinsic reaction pathways. The results show that temperature is the core driving factor for lignin gasification. With the increase in temperature, C-C and C-H bonds continuously cleave; C-O bonds first decrease due to initial decomposition and then increase due to the enhanced formation of CO, which promotes the conversion of lignin from solid phase to liquid phase and further to gas phase. At high temperatures, the gas phase becomes the dominant product. Key findings reveal fundamentally different regulatory effects between the 2 atm: the CO2 atmosphere exhibits higher reactivity and preferentially attacks C-C bonds, leading to thorough solid-liquid conversion at low temperatures, and generating a high yield of CO (approximately 1180 molecules) at 3500 K. Conversely, the H2O atmosphere has low initial reactivity, preferentially attacks C-O bonds, and requires higher temperature (>2600 K) to accelerate reactions. Moreover, thermal decomposition dominates at high temperatures, resulting in the gas phase yield of the H2O atmosphere surpassing that of the CO2 atmosphere. Mechanistically, CO2 promotes CO formation through C-C bond cleavage and water-gas shift reaction, whereas H2O promotes H2 formation through water-gas reaction and hydroxyl group interaction. By uncovering these distinct intrinsic mechanisms, this study highlights specific applications for biomass gasification technology. It provides theoretical guidelines for tailoring gasification parameters to selectively produce specific high-purity CO or H2-rich syngas, thereby directly assisting in the design of high-efficiency biomass conversion reactors and facilitating the high-value utilization of lignin.

Aiming at the high energy consumption and increased carbon emission problems in the utilization of steel slag magnetic powder sintering, this paper proposes to use cold press molding and then heat treatment process to prepare it into a high-strength agglomerate and put it directly into the blast furnace. Steel slag magnetic powder as the main iron-containing raw materials, with a small amount of iron ore powder to improve the particle size composition, and systematically explore the binder type, moisture addition, molding pressure, particle size composition and heat treatment system on the strength of the agglomerate. The results showed that cement and PSB binder could give better strength of agglomerates at room temperature and high temperature compared with pregelatinized starch, bentonite and water glass; among them, the loss of iron grade of agglomerates prepared by PSB binder was the smallest. The optimized process parameters were: moisture addition of 5%, molding pressure of 87.6 MPa, and heat treatment regime of 600 degrees C-40 min. The compressive strength of steel slag magnetic powder agglomerates prepared under these conditions reaches 2295 N at room temperature, 2 m drop strength about 9 times, and high temperature compressive strength about 2200 N at 700 degrees C, which meets the requirements of blast furnace on the strength of the charge, and provides a feasible way for the high-efficiency and low-carbon utilization of steel slag magnetic powder.

Biomass hydrochar injection into blast furnace is one of the important research topics in the current low-carbon ironmaking process. However, its co-combustion behavior with anthracite in front of blast furnace tuyere and its CO2 emission reduction effect during blast furnace injection are still unclear. In this paper, the elemental composition, microstructure, specific surface area and carbonaceous structure order of biomass hydrochar and anthracite are characterized. The combustion and conversion process of biomass hydrochar and anthracite is studied by thermogravimetric analysis and reaction kinetics model. The results show that compared with anthracite, biomass hydrocahr has the characteristics of higher volatile content, larger specific surface area and lower carbonaceous structure order. With the increase of the biomass hydrochar addition, the combustion curve of the mixture gradually moved to the high temperature region, and the R0.5 increased from 1.53 x 10- 4 to 2.98 x 10-4 s- 1. Among them, the linear relationship between carbonaceous structure order and R0.5 has the highest fitting degree. The Flynn-Wall-Ozawa (FWO) model has a high fit grade, with a maximum activation energy of 195.82 kJ/mol, and the corresponding biochar addition amount is 80 %. Using a mixture of hydrochar (60 %) and anthracite (40 %) in blast furnace injection process can reduce CO2 emissions by about 247.13 kg/tHM. Therefore, the addition of biomass not only effectively promotes the combustion of anthracite, but also achieves the reduction of CO2 emissions.

This study systematically investigates the synergistic co-combustion of biomass hydrochar and coke tar residue (CTR) as sustainable alternatives for blast furnace injection. Hydrochars derived from soybean straw (H-SS) and corncob (H-CC) exhibited high volatiles, low ash, and oxygen-rich functional groups, resembling low-rank coal, while CTR demonstrated high fixed carbon. Structural analyses via scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and Brunauer-Emmett-Teller surface area analysis demonstrated hydrochar's porous morphology and lower graphitization, which enhanced oxygen diffusion and combustion kinetics. Thermogravimetric co-combustion experiments revealed that blending 20% hydrochar with CTR achieved optimal performance, reducing ignition and burnout temperatures while exhibiting the lowest average activation energy calculated by the Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) models. Blast furnace mass-energy calculations further indicated that H-CC-20% reduced CO2 emissions by 12.5 kg/tHM while maintaining stable bosh gas composition and combustion temperatures. This work developed a synergistic approach for achieving waste-to-resource conversion while reducing fossil fuel dependency in ironmaking processes.

This study systematically investigates the impact of externally added waste wood on the reduction behavior of biocarbon-containing pellets during roasting in a rotary kiln. Experimental analyses focused on understanding the effects of key parameters such as carbon addition amount, roasting temperature, and roasting duration on pellet compressive strength, metallization rate, and kiln ring formation. The findings indicate that biochar generated by the pyrolysis of externally added waste wood significantly enhances the reduction reactions in pellets and effectively reduces ring formation tendencies. Industrial computed tomography (CT) was employed to precisely characterize the three-dimensional pore structures of roasted pellets, while scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses provided insights into the microstructural characteristics and crystal structures of pellets, elucidating the microscopic mechanisms by which external carbon addition improves pellet properties and inhibits ring formation. Based on these experimental outcomes, the study proposes optimized process parameters suitable for low-carbon ironmaking technology, offering theoretical and technical support for achieving low-carbon and sustainable transformation in the steel industry.

Hydrothermal carbonization (HTC) technology converts biomass into a carbon-rich, oxygen-containing solid fuel. Most studies have focused on hydrochar produced under laboratory conditions, leaving a gap in understanding the performance of industrially produced hydrochar. This study comprehensively analyzes three types of industrially produced hydrochar for blast furnace (BF) injection. The results indicate that hydrochar has a higher volatile and lower fixed carbon content. It has a lower high heating value (HHV) than coal and contains more alkali matter. Nevertheless, hydrochar exhibits a better grindability and combustion performance than coal. Blending hydrochar with anthracite significantly enhances the combustion reactivity of the mixture. The theoretical conversion rate calculations reveal a synergistic effect between hydrochar and anthracite during co-combustion. Environmental benefit calculations show that replacing 40% of bituminous coal with hydrochar can reduce CO2 emissions by approximately 145 kg/tHM, which is equivalent to an annual reduction of 528 kton of CO2 and 208 kton of coal in BF operations. While industrially produced hydrochar meets BF injection requirements, its low ignition point and high explosivity necessitate the careful control of the blending ratio.

Against the backdrop of escalating global carbon emissions, the steel industry urgently requires a transition toward green and low-carbon practices. As a conditionally carbon-neutral renewable energy source, biochar holds potential for replacing traditional fossil-based reducing agents. This study aims to investigate the mechanism and performance differences between biochar (wood char, bamboo char) and conventional reducing agents (semi-coke, coke powder, anthracite) in the direct reduction process of carbon-bearing briquettes. Through reduction experiments simulating rotary kiln conditions, combined with analysis of reducing agent gasification characteristics, carbon-to-oxygen (C/O) molar ratio control, X-ray diffraction (XRD), and microstructural examination, the high-temperature behavior of different reducing agents was systematically evaluated. Results indicate that biochar exhibits superior gasification reactivity due to its high specific surface area and developed pore structure: wood char and bamboo char show significantly enhanced reaction rates above 1073 K, approaching complete conversion at 1173 K. In contrast, anthracite and coke powder, characterized by dense structures and low specific surface areas, failed to achieve complete gasification even at 1273 K. Pellets containing bamboo char achieved the highest metallization rate (90.16%) after calcination at 1373 K. The compressive strength of the pellets first decreased and then increased with rising temperature, consistent with the trend in metallization rate. The mechanism analysis indicates that the high reactivity and porous structure of biochar promote rapid CO diffusion and synergistic gas–solid reactions, significantly accelerating the reduction of iron oxides and the formation of metallic iron.

In this paper, the characteristics of low-rank coal for blast furnace injection after hydrothermal carbonization treatment was studied. The impact of the hydrochar injection on human health, energy, environment and other factors was discussed through the life cycle assessment method. Compared with pulverized coal injection, the hydrochar can improve the sustainability of the ecosystem and the healthy development of human beings. The impact on human health dropped from 24.61Pt to 23.73Pt, the ecosystem dropped from 0.53Pt to 0.51Pt, and the energy utilization rate dropped from 0.31Pt to 0.3Pt. Human carcinogenic toxicity, global warming, freshwater ecotoxicity and mineral resource scarcity are the most significant impacts. After using hydrochar, due to the increase of heat in front of the tuyere raceway and the improvement of pulverized coal utilization, the effects of optimizing coal gas flow distribution, improving reduction efficiency and strengthening smelting are achieved, thus reducing the impact of toxicity and greenhouse effect. Changes in freshwater ecotoxicity are mainly related to the sintering process and chemical reactions. The injection of hydrochar can make a positive contribution to the impact of ore resources. Moreover, the uncertainty analysis results show that the accuracy of the current model calculation can eliminate potential error risks. Thus, the application of hydrochar provides a better solution for the innovative, sustainable development and low-carbon production of iron-making process.