Abstract:As an important secondary resource of the iron and steel industry,blast furnace smelting dust is rich in valuable metals such as zinc and also contains potentially toxic elements.Its efficient and clean recycling is economically valuable and contributes to environmental protection.Hydrometallurgy has become a research hotspot in the field of dust recycling due to its operational flexibility,high selectivity,low energy consumption,and environmental compatibility.This paper reviews the research progress in zinc leaching technology,systematically analyzes the process characteristics and main bottlenecks of acid,alkaline,and ammonia leaching methods,discusses the innovative approaches such as physical field enhancement and process coupling,and anticipates future directions for technology development.The results show that the efficiency of acid leaching of zinc can reach 80％-95％,but it has poor adaptability to highly alkaline and silica-alumina-rich materials,and is often accompanied by the co-solubilization of impurities such as Fe3+and Al3+,which increase the difficulty of subsequent purification.The alkali method exhibits excellent selectivity for zinc oxide.However,its leaching rate stability is system-dependent,and its capacity for amphoteric metals is limited.Additionally,equipment corrosion remains a challenge.The ammonia method achieves high selectivity through the formation of zinc-ammonia complexes,with a leaching rate of 85％-92％,and the dissolution rate of impurity elements such as Fe and Al is below 5％.However,challenges related to ammonia evaporation loss and the complexity of its recycling and reuse limit its application prospects.In recent years,physical field enhancement technologies(e.g.,ultrasonic,microwave,and electric fields)have effectively improved zinc leaching efficiency by modulating reaction kinetics and optimizing mineral phase transformations.For example,ultrasonic cavitation enhances interfacial mass transfer through mechanical vibration and cavitation effects,significantly shortening the reaction time.The magnetic field promotes the transformation of ferromagnetic mineral phases,enhancing the selective release of valuable metals.The electric field guides electron migration,enabling the preferential dissolution of specific metals.In addition,the combined use of innovative processes such as multi-stage countercurrent leaching and ionic liquid extraction has enhanced both the recovery rate and purity of zinc.However,technical challenges remain,such as the complex chemical speciation of zinc in dust(e.g.,iron zincate,zinc silicate)and the need for optimizing system energy efficiency.In the future,efforts should integrate the design of mineral phase reconstruction with the development of green leaching agents.A closed-loop recycling process should be established,along with the construction of a multi-technology synergy and intelligent control system.These efforts aim to achieve high efficiency,low carbon emissions,and economic upgrading of hydrometallurgy,while promoting the resource utilization and sustainable development of metallurgical solid waste.Ultimately,this will help achieve the synergistic goals of minimization,resource recovery,and harmlessness.

Abstract:The removal of hydrogen sulfide(H2S)from blast furnace gas is crucial for achieving ultra-low emissions in the iron and steel industry.After passing through the top gas recovery turbine(TRT)unit,the blast furnace gas temperature typically ranges from 50 to 80 ℃.Ferric hydroxide(α-FeOOH)exhibits high activity at low temperatures,making it an ideal adsorbent for H2S after water treatment.α-FeOOH was doped with Zn2+at different molar ratios(1％,5％,and 11％)via co-precipitation crystallization.A combined fixed-bed and gas chromatography platform was used to evaluate the H2S adsorption capacity in the simulated blast furnace gas atmosphere.The results showed that the H2S adsorption capacity increased to 292.2 mg/g,a 137％ improvement.The physical and chemical properties of the adsorbents were characterized using BET,EPR,and XPS.The results indicated a significant increase in the specific surface area of the Zn/FeOOH samples,rising by approximately 60％.This enhancement leads to more reaction interfaces available for H2S adsorption,providing additional active sites for H2S molecules,which is crucial for improving sulfur capacity.Additionally,the pore volume increased by about 116％,mitigating the pore blockage typically caused by reaction products.All Zn/FeOOH samples displayed characteristic peaks associated with oxygen vacancies at g=2.002,with the Zn/FeOOH-11 sample showing the highest intensity of the oxygen vacancies.This suggests that Zn doping considerably boosts the oxygen vacancies within the material.The introduction of Zn2+ions into the α-FeOOH lattice creates local stress and distortion due to the mismatch in ionic radius and charge between Zn2+and Fe3+.This mismatch facilitates the escape of oxygen atoms,resulting in the formation of oxygen vacancies;these vacancies serve as active sites for the adsorption and activation of H2S molecules,thereby enhancing the catalytic activity of the material.Furthermore,the proportion of monohydroxyl groups in Zn-doped α-FeOOH increased to 36％.These monohydroxyl groups are pivotal for improving sulfur capacity,as they are highly active and can form hydrogen bonds with H2S molecules,further enhancing their adsorption on the material surface.In situ infrared spectroscopy analysis revealed that Zn functions as a catalyst component and also directly interacts with H2S to form ZnS.This Zn doping enhances the catalytic performance of α-FeOOH and influences the types of sulfur products generated.The alterations in structure and surface properties significantly enhance the adsorption and conversion capacity of Zn/FeOOH materials for H2S,providing a reference for increasing the sulfur capacity of the adsorbent and enhancing blast furnace gas purification technologies.

Abstract:China is the world's largest producer of steel and chemicals,the production of which heavily relies on coal resources.Although China's steel industry has made considerable progress in reducing energy consumption,the total annual energy consumption continues to rise due to the industrial scale and increased production capacities.The"Carbon Peak and Carbon Neutrality"initiative has accelerated China's energy revolution,driving the development of emerging energy sources and the construction of a modern energy system.Due to limitations in energy resources,it is difficult for China's steel industry to adopt electric arc furnaces(EAFs)on a large scale in the short term.The traditional blast furnace/basic oxygen furnace(BF-BOF)integrated steelmaking route is characterized by a high-carbon energy structure,a significant crude steel output,and complex carbon emission mechanisms.This process also produces steel mill gases,primarily composed of coke oven gas(COG),blast furnace gas(BFG),and Linz-Donawitz gas(LDG).Currently,steel mill gases are primarily used as fuels,a practice with relatively low energy conversion efficiency.However,the hydrogen,carbon monoxide,carbon dioxide,and methane within these gases represent valuable sources for chemical production.Through continuous technological advancements in recovering surplus steel mill gases for use in chemical manufacturing,the steel and chemical industries can collaborate to achieve energy conservation,emission reduction,and sustainable development.This study examines the generation and utilization of gases across various steel production processes in the context of China's energy structure and the development status of its steel and chemical industries.It also reviews domestic and international cases of integrated steel-chemical production and gas resource utilization,analyzes the current state and potential for synthesizing chemical products from steel mill gases,and proposes strategies to accelerate the adoption of new steel-chemical integration technologies.The ultimate goal is to establish a novel,sustainable industrial ecosystem,with the steel industry as the foundation,in synergy with the chemical industry.Achieving the long-term goal of"Carbon Peak and Carbon Neutrality"in China's steel industry will depend on advancing hydrogen metallurgy,carbon capture,utilization,and storage(CCUS)technologies,along with institutional reforms and policy support.In addition,the application and development of life cycle assessment(LCA)research can track the carbon footprint of the steel industry in more detail and systematically analyze its energy consumption and environmental impact.However,systematic LCA analyses of China's steel industry are still limited.Overall,realizing China's carbon neutrality objectives will require broader cross-disciplinary approaches and innovative strategies.

Abstract:Against the backdrop of China's"Dual Carbon",CO emission reduction technologies are crucial in the sintering process.We employed Computational Fluid Dynamics(CFD)to develop separate models for the combustion of fuel particles and for sintering machines.Numerical simulations were conducted to study the effects of oxygen concentration on fuel particle combustion and the combustion process within the sintering bed.For fuel particles,increasing oxygen concentration effectively improves conditions for complete combustion,enhances fuel combustion efficiency,and reduces CO emissions.Higher oxygen levels promote more thorough oxidation reactions,ensuring a greater proportion of fuel conversion to carbon dioxide(CO2)rather than carbon monoxide(CO).However,the influence of oxygen concentration on fuel combustion behavior during sintering is more complex.Internal fuel combustion in the sintering bed is simultaneously affected by heat transfer and oxygen concentration within the material layer.Increasing oxygen concentration leads to a lower fuel ignition point,extending the high-temperature zone and increasing oxygen consumption due to incomplete combustion.When the increase in oxygen concentration is small,the proportion of incomplete fuel combustion increases.This is because the additional oxygen initially promotes faster ignition but does not sufficiently support complete combustion throughout the sintering bed layer.Consequently,when the oxygen concentration reaches 23％,the sintering combustion efficiency decreases to 94.4％,the sintering temperature drops,and the CO concentration in the combustion products increases.This phenomenon highlights the delicate balance between oxygen availability and combustion dynamics during sintering;insufficient oxygen results in incomplete combustion and increased CO emissions.Further oxygen concentration increases,combined with rising layer temperature,optimize the kinetic conditions for CO secondary combustion.This indicates that excess oxygen supports initial combustion and facilitates further CO oxidation to CO2 in the high-temperature regions of the sintering bed.Consequently,the sintering combustion efficiency improves,and the CO emission concentration decreases.When the oxygen concentration is increased to above 27％,the combustion efficiency exceeds 94.9％,significantly optimizing fuel utilization efficiency during sintering and reducing CO emission concentration in the sintering flue gas.This indicates a threshold oxygen concentration beyond which the benefits of enhanced combustion efficiency and reduced emissions become pronounced.These findings highlight the importance of carefully controlling oxygen levels during sintering to achieve both energy efficiency and environmental goals.This study provides valuable insights into how oxygen concentration improves combustion efficiency and reduces emissions during sintering,contributing to energy efficiency and environmental protection in industrial applications.

Abstract:Developing low-temperature catalytic mineralization technology has become an important research direction for the treatment of volatile organic pollutants(VOCs).Using toluene as the model pollutant,we combine MnO2,which has both catalytic oxidation activity and microwave absorption ability,with microwave irradiation to mineralize toluene into CO2 and H2O at low temperatures ranging from 100 ℃ to 200℃.Four different crystalline phases of MnO2 catalysts(α-MnO2,β-MnO2,δ-MnO2,and γ-MnO2)were successfully synthesized by the hydrothermal method.The catalytic oxidation activity and microwave utilization potential of the different catalysts were evaluated quantitatively,considering both physicochemical and microwave properties.XRD results confirm the successful synthesis of the four distinct crystalline phases.SEM and BET results show that δ-MnO2 has a higher specific surface area(115.3 m2/g)and larger pore volume(0.458 cm/g)due to its porous structure.Through the heating experiment,it was found that 8-MnO2 shows better microwave conversion ability.When the microwave output power was 400 W,600 s was required for δ-MnO2 to rise from room temperature to 300 ℃,which was lower than that of α-MnO2,β-MnO2,and γ-MnO2.Combined with the vector network test results,we found that δ-MnO2 exhibits the strongest reflection loss,impedance matching,and maximum attenuation constant,indicating better microwave absorption and utilization ability.By comparing the mineralization performance under microwave irradiation,we conclude that the crystalline structure significantly affects the catalytic activity of MnO2.δ-MnO2 exhibits a superior low-temperature mineralization performance,achieving complete mineralization temperature at 195℃with a gas hourly space velocity(GHSV)of 18 000 h-1.The order of toluene mineralization activity is determined to be:δ-MnO2＞α-MnO2＞γ-MnO2＞β-MnO2.Moreover,δ-MnO2 shows an outstanding stability,whose toluene mineralization efficiency remains stable with increasing reaction time.Moreover,we used GC-MS to analyze the degradation products of toluene at different catalytic temperatures.GC-MS results reveal that the main by-products of toluene degradation are esters,ketones,and other organic compounds.The type of toluene degradation by-products decreases as the reaction temperature increases.At a temperature of 200 ℃,toluene is completely oxidized to CO2 and H2O without the generation of organic products.Through comprehensive characterization,analysis of electromagnetic properties,and experimental results,we found that the excellent low-temperature oxidation characteristics of δ-MnO2 are related to its unique microstructure,including crystallinity,specific surface area,pore volume,and pore size.The rich void structure of δ-MnO2 enhances the absorption and attenuation of microwaves,exhibiting optimal microwave absorption and utilization properties.

Abstract:The steel industry is one of the most energy-intensive and carbon-emitting sectors worldwide,significantly contributing to environmental challenges.As the world shifts toward more sustainable and eco-friendly industrial practices,there is increasing pressure on the steel industry to adopt technologies that mitigate its environmental impact while enhancing energy efficiency.One promising technology is steel chemical co-production,which effectively addresses these challenges by utilizing by-products such as waste heat,waste gas,and carbon dioxide(CO2)generated during the steelmaking process.This innovative approach is critical for the steel industry's low-carbon transformation and offers a viable path toward green manufacturing.Steel chemical co-production technology focuses on capturing and repurposing by-products generated during steel production.Traditionally,processes like blast furnaces and converters produce substantial amounts of waste heat and gases,much of which remains unutilized,leading to inefficiency and environmental harm.Through co-production technology,these by-products can be converted into valuable forms of energy,such as electricity and heat.A key innovation is the treatment of CO2,which is often released in large quantities during iron ore reduction.By converting CO2 to CO,it can be used as a fuel for further smelting or for generating additional energy,thus closing the loop in steel production.One significant advantage is its potential to reduce CO2 emissions.Steel producers can capture CO2 from various stages of steelmaking,including the blast furnace and converter,and recycle it into usable energy.Reports indicate CO2 emissions can be reduced by over 30％ across the entire steel production process,with reductions of up to 27.25％ specifically during the converter process.This substantially contributes to the industry's overall sustainability goals,achieved through the direct recycling of CO2 and enhanced production system efficiency,thereby decreasing the need for additional energy inputs.The economic viability of steel chemical co-production is another critical factor.While initial investments in advanced co-production technologies may be substantial,long-term benefits are significant.By optimizing energy usage and reducing carbon emissions,steel producers can lower operational costs over time.These savings can offset the initial investment,making the technology economically attractive.Furthermore,as environmental regulations become more stringent and carbon pricing mechanisms are introduced worldwide,steelmakers adopting co-production technologies are likely to benefit from regulatory incentives,such as tax breaks or carbon credits,further enhancing the technology's economic feasibility.In conclusion,steel chemical co-production technology offers a promising solution to the dual challenges of reducing energy consumption and carbon emissions in the steel industry.By recycling CO2 and other by-products,this technology enhances energy efficiency,lowers emissions,and provides an economically viable route for steelmakers to contribute to a more sustainable future.As the technology matures and gains widespread adoption,it will play a crucial role in helping the steel industry meet its environmental and economic challenges,aligning with the broader goals of green and sustainable development.

Abstract:The by-product thenardite(sodium sulfate),generated during wet flue gas desulfurization,poses significant environmental and land-use challenges due to its inherent chemical properties and low resource recovery efficiency.This study addresses this issue by developing a novel approach that leverages modified ion exchange membranes in the electrodialysis process to optimize the separation efficiency of sulfate and sodium ions,facilitating the resource utilization of thenardite.Cation exchange membranes were enhanced through modification with pyrrole and tetraethyl orthosilicate to improve their mechanical strength and sodium ion migration.Anion exchange membranes were treated with polyethyleneimine and dopamine to optimize their surface structure and increase selective permeability for sulfate ions.Characterization techniques,including Fourier transform infrared spectroscopy(FTIR)and scanning electron microscopy(SEM),revealed that the modified membranes exhibited a significantly enhanced surface negative charge,a more uniform pore distribution,and improved structural compactness.Contact angle measurements indicated that these modifications increased membrane hydrophilicity,thereby increasing ion migration efficiency.Experimental results demonstrated that sodium ion permeability increased by 0.36％for pyrrole-modified cation exchange membranes compared to unmodified membranes,while dopamine-modified anion exchange membranes achieved a 12.57％ improvement in sulfate ion permeability.Further electrodialysis experiments showed that,under an applied voltage of 50 V at room temperature,the combination of modified membranes enabled efficient separation of sulfate and sodium ions,achieving a purity of 99％.Notably,after six testing cycles,the modified membranes exhibited excellent stability in ion selectivity and migration efficiency,meeting the requirements for long-term industrial operation.This study innovatively integrates multiple modification strategies to optimize ion exchange membranes,significantly enhancing the separation efficiency and operational stability of the electrodialysis process for thenardite resource utilization.The findings provide crucial technical support for the green resource recovery of thenardite and offer a reference for the treatment of complex industrial wastewater.

Abstract:Elemental mercury(Hg0)and chlorinated volatile organic compounds(CVOCs),which are highly toxic,exhibit significant migration and transformation capabilities,making them prone to forming various secondary pollutants in the atmosphere.This poses severe threats to human and environmental health,attracting widespread global attention.Despite numerous studies,controlling mercury and CVOCs in industrial flue gas remains a significant research challenge.Notably,there are few reports on the impact of CVOCs on the low-temperature adsorption of Hg0.This study investigated the low-temperature adsorption performance of various common adsorbents for Hg0,specifically assessing the effect of CVOCs using chlorobenzene as a model compound.We prepared three types of materials:activated carbon and its modified materials,sulfide,and metal oxides,and evaluated their Hg0 adsorption activity at low temperature(80-120 ℃).The adsorption performance was ranked as follows:CuS/AC＞CuS＞Mn2O3＞AC＞HCl/AC.Brunauer-Emmett-Teller(BET)analysis indicated no direct relationship between the specific surface area or pore type of the adsorbents and their Hg0 adsorption performance.In contrast,X-ray photoelectron spectroscopy(XPS)results revealed that oxidizing species such as Cu2+,S2-,and Mn3+in CuS and Mn2O3 served as the primary active sites for the chemisorption of Hg0.After adding chlorobenzene,the adsorption performance of CuS/AC and AC remained unchanged,while the other three materials exhibited inhibited performance,particularly Mn2O3,whose adsorption efficiency decreased by over 50％.Hg0 temperature-programmed desorption(TPD)experiments demonstrated that HgS was the predominant form of mercury in CuS/AC and CuS when only mercury was present in the flue gas.In Mn2O3,HgO was the primary form,accompanied by some physically adsorbed mercury,whereas AC only facilitated physical adsorption of Hg0.In HCl/AC,both HgCl2 and physically adsorbed Hg0 were detected.Following the addition of CVOCs,the main form of mercury in CuS remained HgS,while physically adsorbed mercury appeared in CuS/AC.Additionally,Mn2O3 exhibited a new adsorption component,HgCl2.Kinetic analyses indicated that the adsorption process of Hg0 across different adsorbent materials conformed to a pseudo-first-order kinetic model(R2＞0.99),highlighting the dominant role of external diffusion.The presence of chlorobenzene further enhanced the chemisorption of Hg0 by HCl/AC and Mn2O3.Moreover,the Hg0 adsorption capacities of AC,HCl/AC,CuS,and Mn2O3 decreased significantly in the presence of chlorobenzene,dropping from 842.5,573.4,55 505.6,and 3 352.6 μg/g to 730.3,181.7,5 504.1,and 434.0 μg/g,respectively.By exploring the effects of CVOCs on the adsorption of Hg0,this study contributes valua-ble insights for future research on low-temperature co-adsorption methods involving Hg0 and CVOCs.