Blast Furnace Coke Research Articles

Впровадження технології трамбування на діючих коксових батареях

DOI: 10.31081/1681-309X-2024-0-2-14-28 Specialty 161. U.D.C. 662.74.2 IMPLEMENTATION OF TAMPING TECHNOLOGY AT OPERATING COKE OVEN BATTERIES © S.O. Kravchenko, Ph.D. in Technical Sciences (STATE ENTERPRISE "STATE INSTITUTE FOR DESIGNING ENTERPRISES OF COKE OVEN AND BY-PRODUCT PLANTS'' (SE "GIPROKOKS''), 61002, 60 Sumska str., Kharkiv, Ukraine), D.V. Miroshnychenko, Doctor of Technical Sciences (National Technical University "Kharkiv Polytechnic Institute", 2, Kyrpychova str., Kharkiv, 61002, Ukraine), V.V. Koval, Ph.D. in Technical Sciences (STATE ENTERPRISE “UKRAINIAN STATE RESEARCH INSTITUTE FOR CARBOCHEMISTRY (UKHIN)”, 7 Vesnina str., Kharkiv, 61023, Ukraine), M.O. Solovyov, Ph.D. in Technical Sciences, S.Y. Abdullin, S.G. Grankin (SE "GIPROKOKS'') The article is devoted to verification of ensuring the appropriate economy and efficiency of coke production while reducing the level of consumption of scarce raw materials in order to optimise production in the current conditions of a coke-chemical enterprise. It is shown that the production of blast furnace coke using the technology of tamping the coal charge allows the use of a large amount of cheap gas coal without reducing the quality of the resulting blast furnace coke. However, despite the fact that this coking technology has been in use for a long time, the literature data on the impact of increasing the loading density on coke quality parameters is insufficient, contradictory and outdated. This article describes the main technical solutions for the conversion of an existing coke oven battery from the bulk coking chamber loading technology to the tamped coal cake loading technology and presents the results for the reconstructed coke oven battery. This project was developed and implemented by SE “GIPROKOKS” and HuDe. The economic and technological indicators of coke quality as a result of the conversion of the existing coke oven battery to the technology of loading a tamped coal cake were considered and compared with the parameters of its operation using the technology of bulk loading of coking chambers. It is shown that during the control period of observations (19 months) of the enterprise's operation, the mechanical strength of M25 coke increased on average from 85.2 to 87.4 %; post-reaction strength CSR – from 48.9 to 53.9 %; at the same time, the abrasion index M10 decreased from 8.0 to 5.9 %, and the reactivity CRI – from 38.0 to 37.2 %, respectively, when working using the tamping technology compared to the bulk method. In addition, the coke obtained by using the charge tamping method is characterised by lower values of ash and total sulphur content. Keywords: coke oven battery, charging, bulk (gravity) method, tamping technology, coal cake, coke properties. Corresponding author S.O. Kravchenko, e-mail: sa_kravchenko@giprokoks.com

Вплив добавок на показники якості коксу

DOI: 10.31081/1681-309X-2024-0-2-3-14 Specialty 161. U.D.C. 662.7:552.57 INFLUENCE OF ADDITIVES ON COKE QUALITY PARAMETERS © D.V. Miroshnychenko, Doctor of Technical Sciences, O.I. Zelenskii, Ph.D. in Technical Sciences (National Technical University "Kharkiv Polytechnic Institute", 2, Kyrpychova str., Kharkiv, 61002, Ukraine), O.L. Borysenko, Ph.D. in Technical Sciences, V.V. Koval, Ph.D. in Technical Sciences (State Enterprise “Ukrainian State Research Institute for Carbochemistry (UKHIN)”, 7 Vesnina str., Kharkiv, 61023, Ukraine), E.L. Solovyov (NTU “KhPI”), S.V. Pyshyev, Doctor of Technical Sciences (Lviv Polytechnic National University, 12, S. Bandera Str., Lviv, 79013, Ukraine) The article is devoted to the study of the possibility of identifying the influence of various additives on the quality of laboratory coke, including the electrical resistance of its structure. Inorganic powders of silicon and silicon carbide (carborundum), as well as an organic additive of petroleum coke, were used as charge modifiers. It is shown that the use of inorganic powder additives will be especially relevant for coal charges with poor coking properties. The obtained results show that the introduction of non-sintering inorganic additives in the amount of 0.125 to 0.5 % by weight allows regulating the processes in the plastic state in order to increase the strength of coke. In particular, the addition of SiC leads to a significant increase in the hot strength index (CSR) and a decrease in the reactivity index (CRI). The improvement of these coke parameters using SiC additives was confirmed by the analysis of other physical and chemical properties of coke. The specific effect of such a modification on coke quality depends on the grade composition of the coal charge. The data presented in the article indicate an increase in the degree of orderliness of the coke structure and the appearance of a larger number of nanostructures when petroleum coke additive is introduced into coal blends in the amount of 5 % by weight. Such modification of the charge also leads to an increase in the yield of gross coke by 1.2-1.3 %; an increase in the total sulphur content in coke by 0.15-0.23 %; a decrease in the ash content of coke by 0.2-0.3 %; deterioration of mechanical strength (P25 – оby 0.1-0.6 %; I10 - by 0.1-0.2 %) and coke strength after reaction (CSR – by 0.6-1.0 %), coke reactivity (CRI – by 0.2-0.3 %), as well as structural strength (SS – by 0.3-0.4 %), abrasive hardness (AH – by 0.7-1.0 mg) and resistivity (ρ – by 0.002-0.007 Ohm×cm). Due to the positive impact of Svyato-Varvarinskaya coal on the quality of blast furnace coke, the quality of coke produced with a higher share of this coal in the charge is improving. On the other hand, when using a coal charge characterised by the lowest content of the aforementioned coal, the quality of the coke produced is rapidly decreasing. Keywords: coal charge, blast furnace coke, quality, modification, additives, petroleum coke, silicon carbide. Corresponding author O.L. Borysenko, e-mail: zd@ukhin.org.ua

Ефективність використання коксу із заданими значеннями питомого електричного опору

DOI: 10.31081/1681-309X-2024-0-2-28-32 Specialty161, 051. U.D.C. 661.66.2:537.311/.312 EFFICIENCY OF COKE UTILISATION WITH SPECIFIED VALUES OF ELECTRICAL RESISTIVITY © V.V. Vladymirenko, N.M. Dyakova (National Technical University "Kharkiv Polytechnic Institute", 2, Kyrpychova str., Kharkiv, 61002, Ukraine), I.V. Shulga, Ph.D. in Technical Sciences, (State Enterprise “Ukrainian State Research Institute for Carbochemistry (UKHIN)”, 7 Vesnina str., Kharkiv, 61023, Ukraine) The article shows that ensuring the specified values of coke resistivity for different directions of its use allows achieving a positive effect in metallurgical production. It is noted that the resistivity of coke for modern blast furnaces using pulverised coal should be minimal. This is ensured by the proper final coking temperature, which makes it possible to obtain coke with the required level of readiness – the final temperature should be at least 1100 оС. This reduces not only the specific electrical resistance of coke, but also its reactivity. The post-reaction strength of the coke is also significantly increased. This makes it possible to reduce coke consumption for pig iron production and increase the productivity of blast furnaces. As a result, it can be achieved the generation of an additional profit of UAH 377.20 per ton of coke. The resistivity of ferroalloy coke, unlike blast furnace coke, should be as high as possible, which will increase the amount of heat generated in the electric circuit of ferroalloy furnaces and used for endothermic reduction reactions. Therefore, lower coke readiness and lower final coking temperatures are sufficient to produce ferroalloy coke. The use of such coke makes it possible to increase the productivity of electric furnaces for smelting ferroalloys and reduce the consumption of raw materials and electricity. According to the results presented in this article, the additional profit is 4741.37 UAH per ton of coke. The weighted average efficiency of the use of coke with given values of resistivity in the national economy, determined by the volume of coke use in various industries, is 464.48 UAH per ton of coke. Keywords: coal coke, electrical resistivity, post-reaction strength, blast furnace production, ferroalloy production, economic efficiency. Corresponding author I.V. Shulga, e-mail: ko@ukhin.org.ua

“In situ” studies on cokes drilled from tuyere to deadman in a large-scale working blast furnace

The properties and deterioration of coke have a significant impact on the thermal efficiency, fuel consumption, and CO2 emissions of blast furnace. Coke sample drilling is one of the effective ways to investigate coke behaviors in a working blast furnace. However, previous coke sample drilling process involved compressed coke, which cannot accurately reflect the actual condition of coke in blast furnace. Therefore, “in situ” coke samples were drilled for three times from tuyere to deadman in their original positions within a large-scale working blast furnace in the present work. The results show that the coke particle size degradation reaches 85.36 % in the 0–5 m zone at the tuyere level. The proportion of coke size less than 3 mm increases sharply along the tuyere direction, and a new method of calculating the depth of the tuyere raceway zone is proposed for the first time. The study based on the grey relational analysis shows that the depth of the raceway is closely related to the blast volume and the blast kinetic energy. Main factors causing the degradation of coke in the tuyere level are fully revealed in different regions. It is suggested to reduce CaO and alkali metals brought in blast furnace in order to protect coke.

Influence chemical composition of the coal mineral substance on the thermochemical properties blast furnace coke

Influence chemical composition of the coal mineral substance on the thermochemical properties blast furnace coke

Preparation of Formed Coke for Blast Furnace Using Kraft Lignin as a Binder

Preparation of Formed Coke for Blast Furnace Using Kraft Lignin as a Binder

Study on the reduction of Fe2O3 pellets by CO-CO2 and H2-H2O: Reaction kinetics and pore network model

The steel industry contributes to creating an environmentally friendly society by providing high-quality steel and working to develop low-carbon processes. Using hydrogen produced from renewable energy to replace part of coke in blast furnaces is one of the measures to reduce fossil carbon dioxide emissions in the process of steelmaking. In this paper, a series of reduction experiments of Fe2O3 pellets at different temperatures were carried out under three conditions of hydrogen-rich in blast furnace. The variation law between reduction degree and apparent activation energy was calculated. The result shows that when the reduction degree reaches 11% and 70%, the apparent activation energy reaches the peak, which are 38.9 kJ/mol and 19.5 kJ/mol, respectively. This suggests that the reduction process is affected by two or more mechanisms. Then, on the basis of the typical single interface reaction kinetics model, the multistep reduction kinetics model of hydrogen-rich reduction Fe2O3 pellets was established. In addition, based on the results of industrial computerized tomography (CT) analysis, the three-dimensional pore network model and velocity model of Fe2O3 pellets after reduction were established. The coupling relationship between the fractal dimension of pellet pores and reduction atmosphere was studied by introducing fractal theory. Under hydrogen-rich reduction condition, the volume fractal dimension of pore structure of Fe2O3 pellets increases from 2.41 to 2.58. Therefore, the pore structure formed by hydrogen-rich reduction is conducive to the diffusion of reducing gas in the pellet, so as to improve the reduction degree of pellet.

Mechanistic insights and kinetics of torrefaction of pine wood biomasses using solid-state NMR

The purpose of this study is to investigate the potential use of torrefied biomass of the genus Pinus, in the form of wood bark (CC), chips (CV) and wood pellets (PP), as substitutes for metallurgical coke to reduce the high CO2 emissions from the use of metallurgical coke in blast furnaces. Thermogravimetric analysis were used to optimize the torrefaction temperature (250 °C or 290 °C), residence time (30 or 60 min) under inert atmosphere. All of the torrefied biomasses were analyzed to determine physical and chemical characteristics (proximate analyses, ultimate analyses, higher calorific value (HHV), Fourier transform infrared spectroscopy (FTIR) and ss-NMR. The composition of condensable and non-condensable gases formed during torrefaction process were also measured. The results showed that the two most promising biomasses were CV and PP torrefied at a temperature of 290 °C at a residence time of 30 min. The kinetics of torrefaction was analyzed by solid state ss-NMR characterization of the torrefied biomass at different time reactions and temperature (250–290 °C) under inert atmosphere, and followed a pseudo-first order kinetic model. The kinetics of evolution of ss-NMR signals related to C-1 of cellulose; C-4 of cellulose in ordered cellulose; C-4 of cellulose in disordered/amorphous cellulose; C-6 of cellulose, and carbon atoms of methoxyl groups in lignins, at different temperatures were used to estimate the activation energy, and values in the range 11–25 kJ mol−1 were obtained.

Use of Nut Coke in Blast Furnace

Use of Nut Coke in Blast Furnace

Effect of coke reactivity on softening-melting and dripping behaviors of sinter

ABSTRACT The use of high reactivity coke in blast furnaces is an important direction for low-carbon development. In this study, we investigated the effect of coke reactivity on the softening-melting behaviors of the sinter. The results show that the gasification temperature of coke decreased with increasing coke reactivity. With increasing coke reactivity from 24.75% to 45.11%, the initial melting temperature rose from 1294°C to 1312°C, the dripping temperature dropped from 1522°C to 1507°C and the melting region decreased from 228°C to 195°C, respectively. The cohesive zone shifted downward and the thickness narrowed. The permeability index and highest differential pressure dropped from 1219.67 KPa·°C to 607.61 KPa·°C and from 7.0962 KPa to 4.8523 KPa, respectively. Coke with high reactivity can improve the gas permeability of burden. The gas utilization ratio in the softening-melting and dripping processes of the sinter raised by about 2% with increasing coke reactivity.

Gasification and kinetic study on metallurgical cokes in CO2-N2-H2O and CO2-N2 atmosphere

ABSTRACT A high-temperature gas-solid reaction device was used to simulate the gasification of coke in a hydrogen-rich blast furnace, with the gasification reaction of water/anhydrous bulk cokes studied. CO2 and H2O effects on coke gasification kinetics were analyzed in CO2-N2-H2O and CO2-N2 with the experimental temperature of 1173–1523 K, the CO2 content of 15–60%, and the H2O content of 15%. Compared with those of CO2-N2, the gasification reaction rate and carbon conversion rate of cokes in the CO2-N2-H2O mixture were significantly higher. Carbon conversion rates of the CO2-N2-H2O mixture at different temperatures were about 30% higher than those of CO2-N2 on average, and the gasification reaction rate was about 50% higher on average. There were two temperature regions for gasifying cokes in CO2-N2-H2O and CO2-N2 mixtures. At 1,273 K, the gasification reaction is transformed into diffusion control, which is from chemical reaction control. The aggravation of coke gasification by H2O generated after hydrogen reduction of iron ores was mainly reflected at the lower temperature. Besides, the kinetic model analysis showed that random pore model was optimal in describing the gasification reaction of cokes in CO2-N2-H2O and CO2-N2, and the addition of H2O improved the gasification reaction’s activation energy.

Analysis of the coke distribution characteristics in hearth based on blast furnace dissection

The occurrence state and consumption way of coke in blast furnace hearth are of great significance for efficient utilization of blast furnace fuel and low-carbon smelting. In this study, a 2200m3 blast furnace was dissected and core drilling was used to analyze the distribution characteristics of coke in the hearth systematically. It was found that the phases from the hot side of carbon brick to the hearth center were the hot metal channel, CaS agglomerate, slag‑iron-coke bonding phase, scattered coke along the radial direction. A large number of CaS were first found in the hearth with a radial width of 0.8 m. S and K elements were enriched at the interface between slag-coke and iron-coke, which hindered the carburization reaction and renewal mechanism of coke and was not conducive to its efficient utilization. In addition, the ore phase of the coke interface and interior alkali metal salt jointly led to its cracking. The distribution date and utilization ratio of coke in the hearth were clarified. The average coke size was 31.17 mm and the average voidage of the deadman was 40.99%. The mass loss of coke as reducing agent, heat source and carburizing agent during the decline in the furnace were 28.31%, 59.40% and 12.29% respectively.

An Appropriate Approach to Recognize Coke Size Distribution in a Blast Furnace

The size distribution of coke is important in order to decide the burden layer structure and the burden porosity in the shaft of a blast furnace (BF), which fluctuates daily and can be determined by several parameters. It is measured two or three times per shift by screening the raw material. However, the screening method used is random and takes a lot of time and manpower, resulting in the susceptive size distribution of the raw material and delayed operation of the BF. Therefore, in this paper, a new online approach used to measure the size distribution of particles was selected through comparison. Four common algorithms were used to detect the coke particles from images, including the Marker-based Watershed (MW), Histogram of Oriented Gradient + Support Vector Machine (HOG + SVM), Faster Region-based Convolutional Neural Networks (Faster R-CNN), and You Only Look Once (YOLOv3). The results show that the MW and HOG + SVM were not suitable for coke image detection. The average mean average precisions (mAPs) of Faster R-CNN and YOLOv3 were 93.391% and 91.348%, respectively, which meet the requirements of coke particle recognition. However, the YOLOv3 (5.419 fps) was selected as the final coke particle image detection algorithm, which is about 4.3 times faster than the average detection speed of Faster RCNN (1.269 fps). After this, the YOLOv3 and screening were used to detect 100 coke images and to generate particle size distribution statistics. The results show that the two methods are basically consistent. YOLOv3 can be used in the online measurement of BF coke. This research, which is of important value, provides a basis for the online measurement of the particle size distribution of raw material in a BF.

Multi-scale relationship between coke gasification kinetics and its microstructure evolution in the blast furnace

There is a precise theoretical correspondence between the microscopic chemistry and physical structure of coke and its apparent rate constantkreaand pore diffusion coefficientDeffof carbon loss process, and a certain precise mathematical relationship betweenkrea/Deffand the degradation gradient or degradation behavior of coke in blast furnace should exist. This is the key basis for predicting and evaluating coke degradation behavior in blast furnace through coke microstructure. In this work, the evolution relationship between the chemical and physical structure of coke and the macroscopic kinetic parameterskrea,Deffwas studied by gasification experiment of coke with different particle sizes. The results show that with the deepening of coke solution loss, minerals gradually precipitate on the surface of coke, and play a catalytic role in the process of solution loss, resulting in a decrease in activation energy and an increase inkrea. At this point, the micropores in coke expand and merge into mesopores and macropores, the diffusion path of CO2molecule decreases, the diffusion activation energy decreases, andDeffincreases gradually. In the middle and late period of solution loss, the active components in coke are consumed and the ash in coke is precipitated, which increases the activation energy and decreases thekrea. Moreover, the number of macropores in coke is further increased, and the tortuous degree of porous structure is greatly reduced, which leads to the decrease of diffusion activation energy and the increase ofDeff.krea/Deffrepresents the gradient reaction ability of coke on the macro level. The higher thekrea/Deffvalue, the greater the reaction gradient of coke under the same conditions, which further affects the degradation gradient and degradation behavior of coke in the blast furnace.

ВИКОРИСТАННЯ ПОКАЗНИКА ПИТОМОГО ЕЛЕКТРИЧНОГО ОПОРУ ДЛЯ ОЦІНКИ ГОТОВНОСТІ КОКСУ (огляд)

The article provides a review of scientific information on the use of the resistivity index to assess the readiness of coke, which is ultimately determined by the degree of orderliness of the macromolecular structure in the form of graphite-like blocks. In this process, coke acquires semiconductor properties and its resistivity decreases. Coke for modern blast furnaces using pulverized coal should have a minimum resistivity of 0.1 ohm∙cm or less. For other applications (in particular, in ferroalloy production), the resistivity of coke should be higher. It has been shown that the most acceptable method for an objective assessment of the resistivity is the two-probe method of measuring the resistivity of coke powder, a representative sample for which is obtained with minimal time and labor. The main factor that affects the resistivity of the coke produced is the final coking temperature, i.e. this characteristic is indeed an objective indicator of coke readiness. With the increase of the final coking temperature, the supramolecular structure of coke is streamlined, which in a certain way approaches the structure of graphite, and this leads to a decrease in the resistivity of coke. It is concluded that it is necessary to theoretically analyze the processes that lead to changes in the electrical conductivity of coke. This will make it possible to reasonably determine the nature of the dependence of the coke resistivity on the final coking temperature. Determination of the numerical parameters of this dependence, in turn, will make it possible to establish a rational level of the final temperature for coke production for various applications, which is of great practical importance. Keywords:hard coal coke, electrical resistivity, coke readiness, blast furnace coke, ferroalloy coke. Corresponding author І.V. Shulga, e-mail: ko@ukhin.org.ua

Використання показника питомого електричного опору для оцінки готовності коксу (огляд).

The article provides a review of scientific information on the use of the resistivity index to assess the readiness of coke, which is ultimately determined by the degree of orderliness of the macromolecular structure in the form of graphite-like blocks. In this process, coke acquires semiconductor properties and its resistivity decreases. Coke for modern blast furnaces using pulverized coal should have a minimum resistivity of 0.1 ohm∙cm or less. For other applications (in particular, in ferroalloy production), the resistivity of coke should be higher. It has been shown that the most acceptable method for an objective assessment of the resistivity is the two-probe method of measuring the resistivity of coke powder, a representative sample for which is obtained with minimal time and labor. The main factor that affects the resistivity of the coke produced is the final coking temperature, i.e. this characteristic is indeed an objective indicator of coke readiness. With the increase of the final coking temperature, the supramolecular structure of coke is streamlined, which in a certain way approaches the structure of graphite, and this leads to a decrease in the resistivity of coke. It is concluded that it is necessary to theoretically analyze the processes that lead to changes in the electrical conductivity of coke. This will make it possible to reasonably determine the nature of the dependence of the coke resistivity on the final coking temperature. Determination of the numerical parameters of this dependence, in turn, will make it possible to establish a rational level of the final temperature for coke production for various applications, which is of great practical importance. Keywords:hard coal coke, electrical resistivity, coke readiness, blast furnace coke, ferroalloy coke. Corresponding author І.V. Shulga, e-mail: ko@ukhin.org.ua

Експериментальне дослідження залежності питомого електричного опору коксу від кінцевої температури

The dependence of the resistivity on the final coking temperature was studied on cokes obtained from the charge of one of the leading coke plants in Ukraine in a laboratory furnace designed by SE "UKHIN" with electric heating. The increase in the final temperature naturally contributes to an increase in coke readiness and the degree of orderliness of its structure. This is manifested in an increase in coke strength (increased resistance to grinding forces and post-reaction strength, reduced abrasion), increased coke density and porosity, reduced reactivity, volatile substance yield and specific electrical resistance. The increase in the final temperature contributes to the deepening of thermochemical polycondensation processes of coke formation, which causes the loss of additional low-molecular weight products, resulting in a slight decrease in the yield of gross coke and its sulphur content with a simultaneous increase in ash content. The previously theoretically substantiated hypothesis about the exponential nature of the dependence of the decrease in the specific electric coke with an increase in the final coking temperature was experimentally confirmed. Processing of the obtained experimental data made it possible to determine the numerical characteristics of this dependence, which makes it possible to determine the rational level of final coking temperatures when producing coke for various applications. In particular, to produce coke with a resistivity not exceeding 0.1 ohm∙cm, the final coking temperature should not be less than 957 oC. This is in line with the practice of coke production. To produce blast furnace coke with a lower resistivity, a higher temperature is required, while to produce ferroalloy coke with a higher resistivity, on the contrary, a lower temperature level is sufficient. Keywords: coal coke, electrical resistivity, final coking temperature, coke readiness, blast furnace coke, ferroalloy coke. Corresponding author I.V. Shulga, e-mail: ko@ukhin.org.ua

Simulation of the Effects of Hydrogen Injection on the Main Indicators of Blast Furnace and Carbon Dioxide Emission Reduction by Zero-Dimensional Model

The steel industry accounts for about 7% of the total human carbon dioxide emissions, and faces enormous pressure to reduce emissions, especially the blast furnace (BF) process with high carbon dioxide emissions. BF hydrogen injection is one of the important technical measures for emission reduction. However, there are still few studies on the limit of hydrogen injection in BF and the influences of hydrogen injection on the changes of main indicators of BF. To evaluate the limits of BF hydrogen injection and these effects, this paper introduces in detail the application of Excel MMULT (MINVERSE (zone 1), (zone 2)) function to build BF mass and heat balance model and application of the Generalized Reduced Gradient (GRG) nonlinear optimizer of Excel Solver Add-In for BF operation optimization. The paper simulates the effects of hydrogen injection on the replacement of BF coke and pulverized coal, the reduction of CO₂ emission, the increase of production, and the changes of raceway adiabatic flame temperature (RAFT) and top gas temperature (TGT), the use of blast temperature (BT), and oxygen enrichment for thermal compensation. The possible limits of hydrogen injection are simulated. The influences on BF direct reduction degree (Dr), CO and H₂ utilization rate (ηCO and ηH₂) are also simulated. Further, the influences of hydrogen preheating injection on coke ratio, CO₂ emission reduction and use of BT, oxygen-enrichment for thermal compensation are simulated. The paper comprehensively and quantitatively evaluated the various aspects of BF hydrogen injection. The simulation results show that when hydrogen is injected at room temperature (298 K), under condition of full coke, 1250°C BT, oxygen enrichment and maintaining 1800°C RAFT, the maximum CO₂ emission reduction of the BF can reach ~30%. If the allowable RAFT is 1900°C, the maximum hydrogen injection volume is about 1/3 less than 1800°C, and the maximum CO₂ emission reduction will be ~20%. 1 kg/thm of hydrogen injected can replace about 2 kg/thm of carbon; this value varies with BT and oxygen enrichment rate, but is not affected by the composition of the mixed ore.

Microstructure Evolution Behavior of Blast-Furnace Coke under Different Gasification Reaction Conditions

With the development of large-scale blast-furnace and oxygen-rich coal-injection technology, as well as national green and low-carbon policy requirements, the ironmaking process has increasingly strict requirements for blast-furnace raw materials, such as new and higher requirements for coke quality and thermal performance. In this study, the melting loss reaction in a blast furnace was simulated under laboratory conditions and the microstructure evolution of coke after melting loss under CO2 and CO2 + H2O conditions was studied. The results showed that under a CO2 atmosphere, the specific surface area and pore volume of coke and the number of micropores in coke first increased and then decreased with the increase in reaction time, while the average pore size first decreased from 17.289 to 8.641 nm and then increased to 9.607 nm. In the gasification reaction between CO2 and coke, the relative content of the graphitized structure (IG/IAll) increased first, then decreased and then increased with the increase in reaction time, while the change trends of disordered structure (ID3/IG) and unstable structure (ID4/IG) were opposite to IG/IAll, indicating that coke still tended to be more orderly with the increase in time. In the mixed atmosphere of CO2 and H2O, the specific surface area and IG/IAll of coke increased with the increase in H2O content. However, when the proportion of H2O exceeded 50%, the specific surface area decreased slightly, and the pore-size value corresponding to the peak value in the pore-size distribution curve shifted to the right, and the average pore-size increased in the nanosize range.

Effect of alkali (K/Na) metal vapor on the metallurgical properties of coke in CO2–O2–N2 mixed atmosphere

The mixed injection of CO2 and O2 in blast furnace is a novel method. The effect of alkali metal vapor on coke structure was studied by gas phase adsorption method. XRD, Raman and other characterization methods showed that K/Na metal vapor reacted with carbon matrix to form new minerals, which destroyed the original dense aromatic ring structure of metallurgical coke and reduced the high-temperature properties of metallurgical coke. In this work, the influence mechanism of alkali metals on coke in blast furnace in CO2–O2–N2 mixed atmosphere was studied by thermogravimetric analysis. The dynamic analysis results show that when the heating rate is 5 K min−1, the deviation value of VM is only 0.64%, and the corresponding urcm is 1.4%. Other experimental results show similar results, indicating that the product model (VM) has the best simulation effect on the reaction process of metallurgical coke.