The iron and steel production was accompanied by the emission of gaseous and solid phases, containing greenhouse gases and metal pollutants, respectively, constituting environmentally harmful by-products. In this work, waste blast furnace slag containing available alkaline oxides CaO and MgO was used to prepare via the method of co-precipitation and hydrothermal crystallization for carbon capture. The maximum CO2 adsorption capacity of the production reached 4.88 mmol center dot g(-1) under conditions of 75 vol% CO2 and 873 K. The CO2 adsorption process could be accurately described via the Avrami order kinetic model and Fractional order kinetic model with fitting degree exceeding 0.99. The Avrami kinetic model (A3) was identified as the most suitable for describing the CO2 desorption behavior. Additionally, the heating rate exerted little effect on the desorption rate but significantly shortened the desorption completion time. Chemical reactions and CO2 diffusion were identified as sequential limiting factors in the adsorption process, and the underlying reaction mechanism was further elucidated. To address the large volumes of solid slag, this work conducted a feasibility of using solid slag derivatives for flue gas capture, providing theoretical support for subsequent practical application.

Metallurgical slag contains numerous valuable components, but its low utilisation rate has caused significant environmental issues. The synthesis of a slag-based CO2 adsorbent was beneficial for treating solid waste and achieving the carbon peak target of the iron and steel industry. In this study, layered double oxides synthesized from blast furnace slag were employed for CO2 adsorption, and the adsorption performance and industrial application stability were investigated. The breakthrough time and adsorption capacity of adsorbent were 13.67 min and 2.44 mmol‧g-1, respectively. The concurrent adsorption of SO2 affected CO2 adsorption, whereas H2O(g) contributed to the two adsorption processes. Therefore, research on the antisulfur modification of layered double oxides and flue gas desulfurization is necessary for decarbonisation. Considering the effect of multicomponent flue gas on the adsorbent, the number of service cycles of the adsorbent should theoretically not exceed 6, resulting in preferable regeneration performance such that the adsorption capacity reaches 65% of the initial condition within that range. Finally, this novel work offered an innovative path for achieving high-value-added utilisation of blast furnace slag and carbon reduction in the iron and steel industry.

The efficient utilization of the coke oven gas and recovery of steel slag waste heat were difficult problem for iron and steel industry. An innovative integrated technology was put forward to produce syngas by CO2/H2O(g) co-assist coke oven gas reforming reaction with steel slag. A thermodynamic analysis based on the Gibbs free energy and exergy-exergy analysis were conducted for providing the theory guidance of practical application. The syngas could be obtained with main components of H2 and CO under the temperature of 1173 K and 0.10 MPa with different CO2/H2O(g). By adjusting the CO2/H2O(g) addition ratio, the yields of H2 and CO in the equilibrium syngas could be tuned to synthesize organic products. The system of coke oven gas reforming reaction with steel slag had well energy and exergy efficiency. The integrated energy efficiency and exergy efficiency were higher than 77 % and 71 %, respectively. The avoidable exergy loss was significantly greater than the unavoidable exergy loss. Economic feasibility of the technology was analyzed and the resulted significant economic benefits. The systematic research and development of CO2/H2O(g) co-assist coke oven gas reforming with steel slag could facilitate the efficient utilization of by-product and heat energy in the iron and steel industry.

The escalating demanded for Zn and environmental imperatives for sustainable resource management had intensified the focus on recovering Zn from Zn-containing dust generated in iron and steel industry. This review comprehensively examined the formation mechanisms, physical and chemical properties of typical Zn-containing dust and evaluated the current and emerging technologies for Zn recovery. Physical method like magnetic separation and hydrocyclones were preliminary treatments with low Zn enrichment. Hydrometallurgical method showed selectivity in metal dissolution but suffered from corrosion issues. Pyrometallurgical method exceled in high-temperature Zn recovery at the cost of energy and CO2 emissions. Emerging technologies such as microwave and vacuum methods provided eco-friendly alternatives but required further development. Coupling method was presented as a synergistic strategy to enhance Zn recovery efficiency and purity, although with increased operational complexity and costs. Future research directions were identified to optimize existing methods and develop new technologies to achieve implementability, intersectionality, economic viability and intelligent control. This review emphasized the need for a subtle understanding of Zn-containing dust properties and development of innovative, efficient, environmentally friendly treatment technologies to support transition to a circular economy.

An in-depth understanding of co-pyrolysis interaction mechanisms is essential for efficient conversion of raw materials and optimizing the regulation of products. Herein, the interaction between enzymatically hydrolyzed lignin (EHL) and waste tires (WT) during co-pyrolysis was investigated using a novel strategy which combines principal component analysis (PCA) and characterization analysis (e.g., FT-ICR-MS, GC-MS, EPR, and so on). Results indicated that cooperative interactions were observed during the co-pyrolysis of EHL and WT, resulting in measured activation energy lower than theoretical calculation. PCA indicated that co-pyrolysis interaction primarily occurred at 345-470 degrees C and was controlled by WT. The contribution of co-pyrolysis to the activation energy and radical spin concentration was most significant with WT blending ratio of 25 %, while the contribution to the bio-oil yield was most significant when the ratio was 50 %. The mechanism analysis indicated that radical-mediated interactions are the key factors influencing the formation of pyrolysis products. Co-pyrolysis improved the bio-oil quality. When a small amount of WT was blended, the co-pyrolysis was manifested as WT-generated hydrocarbon radicals attacking the chemical sites of EHL-derived aromatic rings to form aromatic compounds with fatty structures. When a large amount of WT was blended, it was manifested as sufficient hydrocarbon radicals promoting the demethylation and dehydration of phenolic compounds to form aromatic compounds through hydrogen transfer. Notably, the aromatics content increased significantly from 0.64 % to 18.67 % when WT blending ratio was 75 %. The findings reveal the co-pyrolysis interaction mechanism from the perspective of free radicals and provide a theoretical basis for the targeted regulation of pyrolysis products.

For meeting requirements of "green steel" and "circular economy", there was great potential and value to synthesize CO2 adsorbent with low price and excellent performance by using multiple solid wastes. In this study, a novel method was proposed to synthesize zeolite by blast furnace slag. CO2 adsorption isotherm, thermodynamic and kinetic were investigated comprehensively. Zeolite exhibited favorable physical and chemical structure. Sips model was more suitable to describe isotherm of CO2 adsorption. CO2 adsorption process of zeolite was a spontaneous adsorption process without additional energy need, which could be determined as physisorption process. Four kinetic models were used to fit experimental data. CO2 adsorption by slag-derived zeolite was complicated multi-path adsorption involving adsorption sites and activity. Film diffusion and intraparticle diffusion were rate-limiting steps for CO2 adsorption by slag-derived zeolite. Generally, it was economically and environmentally beneficial to synthesize zeolite from blast furnace slag to achieve CO2 adsorption.

Iron and steel industry production played an important in construction, machinery manufacturing, aviation and military, as well as generated the huge CO2 emission and environmental pollution. However, a large amount of waste heat resources produced by production units were waste, and the utilization efficiency was only about 50 %. Especially, the utilization efficiency of high-quality slag waste heat was only about 35 %. Therefore, the recovery of waste heat from slag into beneficial resources along with the iron and steel production was to improve the consumption of energy, carbon emission and environmental pollution. This review paper was to aim at giving an overview of the latest technology of slag waste heat recovery by chemical method. Firstly, the mechanism, parameters and equipment of energetic carbon material conversion driven by waste heat were discussed detailed. Secondly, the technology of direction carbonation with hot slag were explored and elaborated as comprehensively as possible. Furthermore, the waste heat using to improve the slag properties and produce high value-added materials were summarized from the aspect of slag resource utilization. Ultimately, problems existing in the development of slag waste heat utilization by chemical method were analyzed and suggested the future direction and challenges. This paper aiming to pave the way for the slag waste heat recovery by chemical method while supporting the industrial application and enhancing the role in the fight against carbon emission reduction for iron and steel industry.

Climate change posed the greatest threat to human sustainable development, and reducing carbon emissions was a pressing issue for all humanity. Among the most energy-intensive and carbon emissions industries, the iron and steel industry (ISI) represented almost 5% of energy consumption and 7% carbon emissions around the world. The ISI faced severe challenges from the “relative constraints” of carbon emissions intensity to the “absolute constrains” of total carbon emissions. Waste heat played an indispensable role in the low-carbon development of ISI. The heat contained in the blast furnace slag (BFS) was considerable, and it was an important position to be occupied. In recent decades, the proposal and development of dry centrifugal granulation (DCG) technology had provided researchers with great encouragement and brought the dawn to overcome the problem of slag waste heat recovery. This technology had been hailed as one of the most suitable technologies to boost sustainable transition of the ISI. This paper provided a detailed review of DCG technology including granulation characteristics of BFS, flight and impingement behavior of slag particles, slag transformation in granulation chamber, waste heat recovery process, etc. Furthermore, the implementation and technical characteristics of semi- and industrialization implementation for DCG technology were explored and elaborated as comprehensively as possible. Ultimately, the problems existing in the development of this technology were analyzed, and suggested the future direction and challenges. This paper aiming to pave the way for the waste heat recovery of BFS while supporting the market penetration and enhancing the role in the fight against climate change for ISI.

Blast furnace slag, a main by-product of ironmaking process, contained high-quality sensible heat, accounting for almost 30 % of total energy consumption in iron and steel industry. This paper proposed CO2 coal gasification method aimed at recovering waste heat from blast furnace slag. Based on Gibbs free energy minimization, influence of temperature, CO2/C, pressure and steam were investigated. Under optimal operating conditions at 1023-1198 K, CO2/C of 1.5-2.0 and atmospheric pressure, total amount of syngas was 2.78 kmol, with 67.1 % CO and 8.79 % H2. Addition of steam could adjust compositions of syngas. H2/CO of syngas reached 1.0, 1.5 and 2.0 when H2O(g)/CO2 were 1.45/0.55, 1.73/0.27 and 1.95/0.05, which could be used as organic raw materials for chemical industry. Meanwhile, energy and exergy efficiencies of coal gasification were found to be 63.84 % and 62.58 %, respectively, under optimal operating conditions. For different syngas products, when H2O(g)/CO2 was 1.95/0.05, exergy loss was the lowest, with internal and external exergy loss amounting to 31.80 % and 2.16 % respectively. These works provided theoretical guidance on use of the coal gasification reaction for recovering waste heat from blast furnace slag and contributed to the achievement of the strategic goal of CO2 energy saving and emission reduction.

A novel thermodynamic equilibrium model for coke oven gas reforming reaction with steel slag was developed and the influence of operating parameters on the integrated process were investigated. The sensitivity analysis revealed that the optimal condition for the reforming reaction was the temperature of 1073 similar to 1173 K, CO2/C of 1.5-2.0 and atmospheric pressure. When the temperature reached 1073 K, H-2 and CO yield exceeded 107.75 kmol and 50.21 kmol, respectively. Meanwhile, the comparison of tar removal condition in the coke oven gas reforming reaction with/without steel slag were conducted. The yield of tar decreased from 2.45 x 10(-3) mu mol to 6.27 x 10(-7) mu mol. Furthermore, the influence of steel slag components on coke oven gas reforming reaction were considered at the range of slag basicity (2.0-5.0) and FeO content (18%-24%). The increase of FeO content was benefited to the conversion of tar components with the C6H6 decreased from 1.96 x 10(-6)mu mol to 6.27 x 10(-7) mu mol. Finally, the mechanism of coke oven gas reforming reaction with steel slag was established. This study offered valuable insights into improving coke oven gas reforming reaction with steel slag and provided the guidance of experiment and industrial production.

To further unlock the circular economy potential of iron and steel industry and achieve peak carbon and carbon neutrality targets, this study provides a comprehensive analysis of the high value-added use of blast furnace slag (BFS) for the synthesis of X-type zeolite. The thermodynamic and dissolution behaviors during acid leaching are investigated through theoretical analysis, identifying the optimal pH is 0-1.63 and Eh is- 1.01-2.00 V. Experiments determine that there are obvious improvement in silica gel leaching ratio at 353 K, 4 mol & sdot;L-1- 1 HCl and V (HCl):m(slag) ratio of 12:1. Obtained silica gel has 91.56% whiteness and 86.86% SiO2. 2 . The optimal conditions for X-type zeolite synthesis are crystallization at 363 K for 6 h, with n(SiO2):n(Al2O3), 2 ):n(Al 2 O 3 ), n(Na2O):n(SiO2) 2 O):n(SiO 2 ) and n (H2O):n(Na2O) 2 O):n(Na 2 O) establishes as 2.8, 2.8 and 45 respectively and resulting material has high crystallinity, purity of crystals and excellent performance. Furthermore, the mechanism is elucidated from the perspective of micro- structural and molecular level. Economic evaluation along with carbon tax assessment indicated that it is economically beneficial both in direct profit and potential CO2 2 capture. These findings emphasize the feasibility, efficacy and economy of X-type zeolite synthesis from BFS, which contributes to turning waste into treasure and promoting the concept of "Green steel".

As main by-product in iron and steel industry, high value-added utilization of blast furnace slag had received extensive attention. In this paper, a novelty technology was proposed for using blast furnace slag as raw material to obtain excellent CO2 adsorbent-layered double oxides. The characteristics of layered double hydroxides and layered double oxides were investigated in detailed. Most notably, the laminate structure of layered double hydroxides collapsed and the pore structure, particle size distribution and functional groups of the sample had been greatly changed. The layered double oxides were occupied by phases of CaO, Ca12Al14O32Cl2 and MgO. The transformation mechanism of the layered double oxides preparation was obtained. In addition, CO2 concentration and temperature influencing on CO2 adsorption of layered double oxides were studied and established a suitable kinetic model. The optimal kinetic mechanism model of CO2 adsorption by layered double oxides was PSO. The activation energy and pre-exponential factors were 56.88 kJ‧mol-1 and 12.26 min-1, respectively. Ultimately, CO2 adsorption capacity comparison and preliminary economic evaluation were conducted to assess the industrial feasibility of this technology. This work achieved the goals between CO2 reduction and high value-added utilization of solid waste in iron and steel industry.

In this work, the direction of allothermal coal pyrolysis reaction was driven by the waste heat of blast furnace slag. The structure features of the coal char mixed with/without slag was characterized by BET and SEM. The experiments of thermogravimetric analyzer were conducted to obtain the coal pyrolysis characteristics. The kinetic parameters of coal pyrolysis reaction were extracted using the reaction model based on the Arrhenius law and Li Chung-Hsiung method. The BET and SEM results showed that the slag addition could improve the structure features of the coal char effectively. The specific surface area, pore volume & size increased significantly. With the slag addition, characteristic temperatures of pyrolysis reaction did not change obviously. Peak temperature and final temperature increased by approximate 3.38 K and 5.55 K, respectively. However, the maximum weight reduce and pyrolysis characteristic index were enhanced dramatically. A single three-order reaction model was used to deduce the coal pyrolysis reaction successfully. The activation energy of the coal pyrolysis reaction decreased from 116.31 kJ center dot mol(-1) to 90.67 kJ center dot mol(-1), and the pre-exponential factor decreased from 6606.19 min(-1) to 2457.91 min(-1). Overall, slag provided the heat for the pyrolysis reaction and acted as the catalyst.

The resource utilization of blast furnace slag was the research hotspot at home and abroad. This study aimed to obtain hydrotalcite-like compounds from slag using co-precipitation method. The optimum process conditions for the synthesis of hydrotalcite-like compounds were investigated using single-factor in a self-designed laboratory-scale system. Furthermore, the synthesis mechanism of hydrotalcite-like compounds was established. The pH of 11.5, precipitation temperature of 343 K, crystallization temperature of 383 K, and crystallization duration of 6- 10 h were shown to be the optimum process conditions for the synthesis of hydrotalcite-like compounds. The leachate formed a typical crystal layered structure of hydrotalcite-like compounds under optimum process conditions through chemical reactions between compounds and sufficient crystallization. The completion of this work provided a new technological path for the utilization of blast furnace slag, which was more conducive to the energy saving and emission reduction of the iron and steel industry.

With the aim of utilizing blast furnace slag in the iron and steel industry at low cost, pollution free, refinement, and high value added, an entirely subversive technical route was presented, which was a novel synergistic utilization of slag to produce zeolite and hydrotalcite-like compounds. The object of this study is to obtain the optimal operating conditions for producing the intermediate product-silica gel. Furthermore, the kinetic characteristic and mechanism of slag leaching reaction were explored. The results suggested that the optimal leaching reaction conditions were achieved at 353 K, 120 min and hydrochloric acid concentration of 4 mol·L−1. Under these conditions, the slag leaching ratio reached up to 95.66% and about 0.38 g silica gel could be obtained from 1 g slag. The quality of silica gel completely satisfied the requirement of industrial standards. Then, the kinetic analysis of slag leaching reaction was conducted, and the leaching rate was controlled by shrinking core model (R3) with the apparent activation energy of 18.69 kJ·mol−1. Meanwhile, the thermodynamic parameters such as ΔH≠ and ΔS≠ were investigated by using the Eyring equation. Ultimately, the mechanism of slag leaching reaction was discussed, and relevant crucial governing equations were derived.

In order to utilize blast furnace slag resource at low cost, pollution-free, refinement and high value-added, a novel technical route was proposed to collaboratively produce zeolite and hydrotalcite-like compound. In this study, the changing property of slag in the treatment process was investigated and the thermodynamic and kinetic analyses of the leaching reaction were conducted to prove its feasibility. The silica gel and residue liquid were separated effectively from the slag. Then, 13X zeolite and hydrotalcite-like compound were successfully synthesized from water quenching blast furnace slag using hydrochloric acid treatment followed by hydrothermal method and co-precipitation method. The successful formation of 13X zeolite and hydrotalcite-like compound were obtained effectively with good surface morphology and crystal structure. Mass balance of the blast furnace slag utilization process was established. Meanwhile, these two samples exhibited good behavior of CO2 adsorption capacity and enjoyed a promising market prospect. The maximum adsorption capacities of 13X zeolite and hydrotalcite-like compound were 116.48 mg g(-1) at 313 K and 149.63 mg g(-1) at 873 K, respectively. Finally, the preliminary economic evaluation of the integrated system was conducted, and the economic benefit of 1 kg slag was about 1.281 $.

Based on the black-box model, this paper analyzed the multi-stage slag waste heat recovery system. The exergy efficiency, the exergy loss coefficient and the exergy loss rate were adopted as evaluation indexes to investigate the energy consumption and the weakness of the system. Meanwhile, the performance of waste heat recovery was analyzed by comparing the comprehensive exergy efficiency between the system and other conventional waste heat recovery methods. The results showed that the comprehensive exergy efficiency of the system reached 75.75%, which was much higher than other methods, and the weakness of the system was the subsystem of waste heat boiler. In general, the system recovered the slag waste heat effectively and converted coal to clean syngas through gasification reaction, which had incredible potential in energy saving, emission reduction and consumption reduction.

A novel method that a heat recovery system from blast furnace slag integrated with coal gasification reaction to generate syngas was proposed. The motion characteristic and critical velocity of the coal particles in the molten slag were estimated. Meanwhile, the effects of temperature and steam to coal ratio on coal gasification product distribution and gas characterization were discussed. The results showed that the coal particles (~75 μm) would break through the bondage of bubbles and transport into molten slag when the velocity of coal particles were above 4.20 m·s-1 and the diameter of bubbles were less 6 mm. There had higher gasification efficiency, gas yield production and H2 production by this method. The results suggested that the optimal conditions for slag waste heat recovery were achieved at 1623 K and steam to coal ratio of 2.0. Under these conditions, the gas yield and carbon conversion reached 133.48 mol·kg-1 and 97.81%, respectively. The proposed method enhanced the coal gasification efficiency and recovered the high quality of molten blast furnace slag waste heat effectively, and had important guidance for industrial manufacture.

The high quality waste heat recovery of the molten blast furnace slag was necessary and urgent. In this paper, the flow characteristic of the molten slag reactor was investigated by numerical simulation. Firstly, the three-dimensional model was established for investigating the gas-liquid two-phase flow. The gas-liquid flow was modeled to be turbulent, which was described by the RNG k-ε model, and the interface of gas and liquid was conducted by the VOF model. Secondly, the top-submerged cold experiment system was constructed to validate the accuracy of the simulation model. Thirdly, the bubble behavior, gas phase distribution and molten slag motion were investigated. The bubble in the reactor would go through five stages and the maximum gas fraction reached about 4.87% at 0.75s. Meanwhile, the gas phase distribution and molten slag motion were closely related to the bubble behavior. Ultimately, the matrix analysis method was applied to obtain the optimal parameters of the reactor. The optimal condition improved the flow behavior in the molten BFS reactor significantly. The present results of the simulation provided an insight for the gas-liquid two-phase flow in molten slag reactor, which would provide the theoretical guidance for industrial applications.

In order to recover the waste heat of molten blast furnace slag, a reactor with top-submerged lance was established. The numerical simulation and experiment study of the flow characteristic in the reactor were conducted. The mathematical model of reactor was established and the Euler-Euler model was employed to simulate the gas-liquid flow in molten slag bath. Meanwhile, the experiment results were obtained and compared with the simulation to testify the accuracy of the established model. According to the bubble behavior in bath, there were four stages: initial expansion stage, bubble detachment stage, freedom lift up stage and bubble broken stage. When the flow field in bath fully developed, the gas fraction decreased with the increasing of bath depth. During injection process, the area near the nozzle and lower the bath would first generate two symmetric heliciform flow regime, and then the flow regime in whole bath would become irregular because of bubble lifting up and rupturing. The gas fraction in bath, the average velocity and turbulence energy of slag would decrease before it increased to maximum and then it would keep fluctuate in a range.