Decarbonization options of the iron and steelmaking industry based on a three-dimensional analysis

Decarbonization is a critical issue for peaking CO_(2) emissions of energy-intensive industries,such as the iron and steel industry.The decarbonization options of China’s ironmaking and steelmaking sector were discussed based on a systematic three-dimensional low-carbon analysis from the aspects of resource utilization(Y),energy utilization(Q),and energy cleanliness which is evaluated by a process general emission factor(PGEF)on all the related processes,including the current blast furnace(BF)-basic oxygen furnace(BOF)integrated process and the specific sub-processes,as well as the electric arc furnace(EAF)process,typical direct reduction(DR)process,and smelting reduction(SR)process.The study indicates that the three-dimensional aspects,particularly the energy structure,should be comprehensively considered to quantitatively evaluate the decarbonization road map based on novel technologies or processes.Promoting scrap utilization(improvement of Y)and the substitution of carbon-based energy(improvement of PGEF)in particular is critical.In terms of process scale,promoting the development of the scrap-based EAF or DR-EAF process is highly encouraged because of their lower PGEF.The three-dimensional method is expected to extend to other processes or industries,such as the cement production and thermal electricity generation industries.

Investigation of the kinetic mechanism of the demanganization reaction between carbon-saturated liquid iron and CaF2–CaO–SiO2-based slags

The demanganization reaction kinetics of carbon-saturated liquid iron with an eight-component slag consisting of CaO–SiO2–MgO–FeO–MnO–Al2O3–TiO2–CaF2 was investigated at 1553, 1623, and 1673 K in this study. The rate-controlling step（RCS） for the demanganization reaction with regard to the hot metal pretreatment conditions was studied via kinetics analysis based on the fundamental equation of heterogeneous reaction kinetics. From the temperature dependence of the mass transfer coefficient of a transition-metal oxide（MnO）, the apparent activation energy of the demanganization reaction was estimated to be 189.46 kJ·mol^–1 in the current study, which indicated that the mass transfer of MnO in the molten slag controlled the overall rate of the demanganization reaction. The calculated apparent activation energy was slightly lower than the values reported in the literature for mass transfer in a slag phase. This difference was attributed to an increase in the ＂specific reaction interface＂（SRI） value, either as a result of turbulence at the reaction interface or a decrease of the absolute amount of slag phase during sampling, and to the addition of calcium fluoride to the slag.

Synergetic pathways of water-energy-carbon in ecologically vulnerable regions aiming for carbon neutrality:a case study of Shaanxi,China

Synergetic energy-water-carbon pathways are key issues to be tackled under carbon-neutral target and high-quality development worldwide,especially in ecologically vulnerable regions(EVRs).In this study,to explore the synergistic pathways in an EVR,a water-energy-carbon assessment(WECA)model was built,and the synergistic effects of water-energy-carbon were comprehensively and quantitatively analyzed under various scenarios of regional transition.Shaanxi Province was chosen as the representative EVR,and Lower challenge(LEC)and Greater challenge(GER)scenarios of zerocarbon transition were set considering the technological maturity and regional energy characteristics.The results showed that there were limited effects under the zero-carbon transition of the entire region on reducing water withdrawals and improving the water quality.In the LEC scenario,the energy demand and CO_(2) emissions of Shaanxi in 2060 will decrease by 70.9%and 99.4%,respectively,whereas the water withdrawal and freshwater aquatic ecotoxicity potential(FAETP)will only decrease by 8.9%and 1.6%,respectively.This could be attributed to the stronger demand for electricity in the energy demand sector caused by industrial transition measures.The GER scenario showed significant growth in water withdrawals(16.0%)and FAETP(36.0%)because of additional biomass demand.To promote the synergetic development of regional transition,EVRs should urgently promote zero-carbon technologies(especially solar and wind power technologies)between 2020 and 2060 and dry cooling technology for power generation before 2030.In particular,a cautious attitude toward the biomass energy with carbon capture and storage technology in EVRs is strongly recommended.

Recovery rates of iron, nickel, and chromium via iron-bath reduction of stainless steel dust briquettes based on corundum crucible erosion balance analysis

The leaching of chromium from stainless steel dust （SSD） is deleterious to the environment. To address this issue, the reduction of SSD briquettes can be employed to effectively extract chromium. The recovery rates of iron, chromium, and nickel via ironbath reduction of SSD briquettes were determined using X-ray fluorescence spectroscopy, X-ray diffraction, and scanning electron microscopy measurements. First, the effects of basicity and contents of silicon, iron, CaF2, and carbon on the recovery rates of the three metals were analyzed using the slag amount prediction model, which was originally established from the A1203 balance of corundum crucible erosion behavior. Second, the effect of feeding mode, i.e., whether steel scrap and SSD briquettes were simultaneously added, on the recovery rates was discussed in detail. Third, the iron-bath reduction of SSD briquettes was thermodynamically analyzed. The results indicated that the recovery rates of the three metals are greater than 95% those of using a basicity of 1.5 and 6.0% CaF2, 15% carbon, and 7% ferrosilicon. The recovery rate of chromium increases twofold with the addition of ferrosilicon. The feeding mode of adding briquettes and steel scrap simultaneously is better for recovery of metals and separation of the metal and slag than the feeding mode of adding steel scrap firstly and then briquettes.

Effect of Coke Reaction Index on Reduction and Permeability of Ore Layer in Blast Furnace Lumpy Zone Under Non-Isothermal Condition

Reasonable control on CRI（coke reaction index）is one of the key factors for BF（blast furnace）low-carbon smelting.However,there are contrary opinions.One is increasing CRI to improve reaction efficiency in BF and the other is decreasing CRI to suppress coke degradation in furnace.Different methods are adopted to realize effective catalysis（increasing CRI）and passivation（decreasing CRI）of coke.Simulation tests of coke in BF lumpy zone under gradual temperature rising have been done.Effect of CRI on gas composition,ore reduction,burden column permeability and heat reserve zone′s temperature under non-isothermal condition are studied.Then combined with iron making calculations,a novel BF operation suggestion is proposed as coke nut with small size be catalyzed and mixed with ore while skeletal coke with large size be passivated and separately charged into BF.

Effect of Nickel on Formation Mechanisms of Silico-ferrite of Calcium and Aluminum(SFCA)

Under the pressures of both the de＇crease of high-grade high quality iron ore resources and the increase of raw material costs, the iron and steel enter＇prises in China turn to adopt iron ores which contain special elements such as nickel, manganese, etc. in the sintering blend. Anaiytica｜ reagents were used for sintering experiments, and the sinters were analyzed with X-ray diffraction, s6ailning electron microscopy and mineralogical microscopy to study the effect of nickel on the silico ferrite of calcium and aluminum （SF（＇A） bonding phase formation during sinte- ring. The results indicated that SFCA was divided into nickel containing and nickel-free areas due to the presence of nickel. The increasing content of nickel would greatly reduce the content of SFCA and promote the formation of calcium aluminum silicate. A great deal of Fe2 Oa participated in the crystal transition to Fe3 O3 , reducing the a mount of Fe2O2 involved in the formation of calcium ferrite. When the blending ratio of NiO, which is used to provide the nickel in the sintering process, is less than 3 % , the calcium ferrite is in substantially interleaving cot rosion with hematite and magnetite. Both the porosity and silicate glass phase content are low, which contributes to the sintering production.

Resource utilization of flue gas calcium-based desulfurization ash:a comprehensive review

Calcium-based desulfurization ash(CDA)is mainly produced in dry and semi-dry flue gas desulfurization processes.The property of CDA is extremely unstable because its main component,calcium sulfite,makes it difficult to be directly applied to the field of building materials.The modification of desulfurization ash can be realized by high-temperature oxidation and wet oxidation.After modification,CDA can be widely used in building materials.Hydrothermal oxidation has broad development prospects because it can complete the oxidation of CDA and the removal of impurity elements at the same time.CDA can be used to prepare high value-added products of calcium sulfate whiskers and ecological rubber fillers.

Critical assessment of mixing thermodynamic functions of Fe-Al binary melts based on atom-molecule coexistence theory

In order to further verify the accuracy and feasibility of the calculated mass action concentrations Ni of Al and Fe by the developed atom and molecule coexistence theory(AMCT)model,i.e.,AMCT-N,model,for representing activities aR,i of Al and Fe in Fe-Al binary melts reported in the first part of the serial studies,the molar mixing thermodynamic functions of Fe-Al binary melts over a temperature range from 1823 to 1973 K have been calculated based on Ni of Al and Fe as well as the effect of temperature on activity coefficients 7,of Al and Fe as■lnγj/■T=■ln(Ni/xi)/dT by the developed AMCTN-Ni model,where T is absolute temperature and.v,is the mole fraction of element i or compound i in metallic melts.The reported molar mixing thermodynamic functions of Fe-Al binary melts as well as the reported excess molar mixing thermodynamic functions of Fe-Al binary melts relative to ideal solution as a basis from the available literatures have been critically assessed and applied as criteria to verify the developed AMCT-Al,model.The effect of changing temperature onγi of Al and Fe,i.e.,activity coefficient gradients■lnγAl/■T and■lnγFe/■T,which are two indispensable parameters to calculate the molar mixing thermodynamic functions of Fe-Al binary melts,can be accurately obtained by the developed AMCT-Ni,model and expressed by the cubic polynomial functions.Not only the partial molar mixing thermodynamic functions of Al and Fe in Fe-Al binary melts but also the integral molar mixing thermodynamic functions of Fe-Al binary melts can be accurately calculated by the developed AMCT-Al,model.Furthermore,the excess partial and integral molar mixing thermodynamic functions of Fe-Al binary melts relative to ideal solution as a basis can also be precisely calculated by the developed AMCT-Ni,model.