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It is generally accepted that the softening–melting properties of ferrous burden play a vital role in optimizing the shape and position of cohesive zone. The effect of quaternary basicity and atmosphere on softening, melting and permeation temperatures of primary slag based on magnesium flux pellet was investigated by visualization method. The mechanisms were analyzed utilizing thermodynamic calculation, X-ray diffraction analysis and electron probe microanalysis. The results indicated that the softening and melting temperatures of oxide samples increased by approximately 120 °C with increasing quaternary basicity from 0.3 to 1.2 owing to the formation of slag phases with high melting point and solid Fe. Meanwhile, the difference between softening and melting temperatures decreased from 21 to 11 °C. The permeation temperature was not affected by the quaternary basicity and fluctuated around a level of 1250 °C, given that the permeation temperature depends on the wettability between slag and coke bed. On the other hand, as the ratios of CO/CO2 varied from 3/7 to 7/3, there were no significant differences in either the softening or melting temperatures, whereas the permeation temperature was increased from 1239 to 1271 °C since the reduction of FeO-bearing phases to solid Fe could decrease the wettability between slag and coke bed.

The effect of MnO and substituting CaO with BaO on the sulfide capacity of CaO-SiO2-MgO-Al2O3-BaO-MnO slag was studied at 1773 K using the gas–slag equilibration technique. The relationship between the sulfide capacity and sulfur partition ratio in equilibrium based on the present slag was discussed. The results indicate when the CaO/SiO2 ratio and other components stay fixed; the sulfide capacity increases with MnO content increasing from 0 to 3 wt pct, which is not only due to an increase of oxygen ion activity but also to the decrease of the activity coefficient of sulfur ions. With the equal mass substitution of CaO with BaO, the free oxygen ions and corrected optical basicity decrease, and the slag structure tends to be complicated because of the compensation effect of Ba2+ for [AlO4]5− tetrahedron uniting. Furthermore, the reduced level of $$ { \log }a_{{{\text{O}}^{2 - } }} $$ is greater than that of $$ \log f_{{S^{2 - } }} $$ , ultimately leading to a decrease of sulfide capacity. In addition, the sulfur partition ratio is obtained from the sulfide capacity in equilibrium and shows a similar changing trend between them as a function of slag composition.

The flux pellets as the burden materials of blast furnace have been widely investigated and used. However, its research and practical applications keep slowly developing in China due to the histori...

The global warming promotes the steel industry to replace part of coke by injecting hydrogen-rich fuel into the blast furnace to reduce CO2 emissions and energy consumption. In this paper, the inje...

At present, the continuous accumulation of the flue gas desulfurization (FGD) gypsum in steel plants leads to the serious environmental issues and resource waste. To achieve green and sustainable development for the steel industry, it is significant to improve the usage of by-product gypsum. Employing the sintering FGD gypsum, ferric oxide, and graphite carbon as raw materials, the effects of the carbon content, reaction time, and molar ratio of CaO to Fe2O3 on the desulfurization rate of gypsum were studied based on the orthogonal experiment. The results show that the order of the three influencing factors on the desulfurization rate of FGD gypsum is: molar ratio of CaO to Fe2O3 > reaction time > carbon content. Under the optimal conditions of 20 wt.% carbon content, 4 h reaction time, and 1:1 molar ratio of CaO to Fe2O3, the desulfurization rate of desulfurization gypsum is 95.79%, and 97.57 wt.% of calcium ferrite appears in the solid product, which can be used as sintering additive to increase the economic benefits of enterprises and realize the green ecological development mode of internal generation and internal digestion of solid waste in iron and steel enterprises.

The gasification reactivity and kinetic parameters of coal chars for non-isothermal steam gasification were investigated. One kind of lignite and three kinds of bituminous coals were used as the samples, and their coal ranks follow the ascending order: XB KL > ZJ > GD. Through systematically analyzing factors affecting gasification reactivity, it was ascertained that the gasification reactivity is mostly determined by the carbonaceous structure. The gasification reactivity is inversely proportional to the coal rank, and the higher the coal rank, the lower the gasification reactivity. A new kinetic model was proposed to calculate the kinetic parameters, in which the reaction order was considered as an unknown kinetic parameter. The reaction order n follows the ascending order: XB

The recent progress and development of ironmaking in China as of 2019 was introduced. China has achieved a remarkable progress in eliminating outdated production capacity of steel industry, accompl...

The high-value utilization of low-rank coal would allow for expanding energy sources, improving energy efficiencies, and alleviating environmental issues. In order to use low-rank coal effectively, the hypercoals (HPCs) were co-extracted from two types of low-rank coal and biomass via N-methyl-2-purrolidinone (NMP) under mild conditions. The structures of the HPCs and residues were characterized by proximate and ultimate analysis, Raman spectra, and Fourier transform infrared (FT-IR) spectra. The carbon structure changes within the raw coals and HPCs were discussed. The individual thermal dissolution of Xibu (XB) coal, Guandi (GD) coal, and the biomass demonstrated that the biomass provided the lowest thermal dissolution yield Y1 and the highest thermal soluble yield Y2 at 280°C, and the ash content of three HPCs decreased as the extraction temperature rose. Co-thermal extractions in NMP at various coal/biomass mass ratios were performed, demonstrating a positive synergic effect for Y2 in the whole coal/biomass mass ratios. The maximum value of Y2 was 52.25wt% for XB coal obtained with a XB coal/biomass of 50wt% biomass. The maximum value of Y2 was 50.77wt% for GD coal obtained with a GD coal/biomass of 1:4. The difference for the optimal coal/biomass mass ratios between XB and GD coals could be attributed to the different co-extraction mechanisms for this two type coals.

Blast furnace ironmaking process is the most mature and highly effective process for producing liquid iron. Blast furnace is a gas–solid and gas–solid–liquid countercurrent reactor, and maintaining gas permeability is the precondition of smooth production. Therefore, improving the gas permeability throughout the blast furnace remains a hot issue which is concerned by many metallurgical scholars. According to the research results of many scholars, the dominant factors influencing the gas permeability of different locations in the blast furnace (locations are distinguished according to the morphology change of the burdens) were reviewed. And the strategies for improving the gas permeability of different locations in the blast furnace were summarized based on these dominant influencing factors, such as suppressing the low-temperature reduction degradation of sinter in the lump zone, improving the indirect reduction degree and suppressing the interaction between different burdens. It is hoped to provide both theoretical and practical values for guiding the blast furnace so as to improve smooth operation and smelting efficiency.

Rapid technological advancements and increasing demand for the efficient utilisation of global resources have promoted the design and development of sustainable anode materials to achieve batteries with high specific capacities and excellent rate capability for energy-storage devices. Herein, a high-performance MnO nitrogen-doped carbon anode material for lithium-ion battery based on coffee residues, potassium permanganate, and urea is presented. MnO and N are uniformly embedded inside the carbon material, connected by N–Mn bonds. The introduction of N not only hinders the aggregation of Mn nanoparticles generated during lithiation, but also enhances the electrochemical activity of carbon and improves the electrical conductivity for better reaction kinetics. These benefitting factors promote the high reversible specific capacity of 768 mA h g−1 at the current density of 0.3 A g−1, as well as superior cyclic and stability performance. The demonstrated high-performance and low-cost anode material also provides a sustainable route for the high-value-added utilisation of waste biomass.

The microstructure of coke has an important influence on its thermal properties. The solution loss reactions of coke in CO2 and H2O atmospheres were investigated by in situ observation. The results showed that the isotropic components had a more vigorous reaction than the anisotropic components, and the solution loss reaction of the fine-grained mosaic structure was faster than that of the coarse-grained mosaic structure under the CO2 and H2O atmospheres. The coarse-grained mosaic structure and the flowing structure had a relatively higher anti-erosion ability in the CO2 atmosphere than in the H2O atmosphere, and there was no distinct difference in the solution loss of the isotropic structure under the CO2 and H2O atmospheres. The electron probe microanalysis showed that the Al–Si–Fe compounds in the carbon matrix had positive influence on the solution loss reaction of the anisotropic structure. The iron compounds were able to destroy the pore walls of coke and accelerate the solution loss rate of coke.

The steel industry accounts for 5% of the world's total energy consumption and contributes 6% of the world's anthropogenic CO2 emissions. The control of CO2 emissions has become increasingl...

The temperature field distribution of the upper part of a blast furnace (BF) is the result of the combination of charge distribution and gas flow. It is of great significance for both researchers and operators to study the thermal state and the phenomenon of the BF. The graphite box method is used in this study to obtain the temperature field distribution in the upper part of a 125 m(3) BE. Graphite boxes with a variety of different melting point metals were loaded into the BF with the charge. And the temperature field distribution was obtained after the boxes were taken out with position and temperature information during the dissection process. The results illustrate that the graphite boxes are unevenly distributed in the BF, which was related to the distribution of BF materials. Furthermore, the temperature field distribution is asymmetric, and the isotherms present an irregular "W" shape, which is caused mainly by the simultaneous development of the edge airflow and the central airflow. Moreover, the shape of the softening and melting zone observed in the dissection process has a good correspondence with the temperature field. We concluded that the deflection of the temperature field and the softening and melting zone is related to the strong gas flow in the direction of No. 3 tuyere, the existence of accretion in the hearth, and the filling of refractory materials in tuyeres before blowing out.

HyperCoal was prepared from low-rank coal via high-temperature solvent extraction with N-methylpyrrolidone as an extraction solvent and a liquid-to-solid ratio of 50 mL/g in a high-temperature and high-pressure reactor. When HyperCoal was used as a binder and pulverized coal was used as the raw material, the compressive strength of the hot-pressed briquettes (each with a diameter of 20 mm and mass of 5 g) under different conditions was studied using a hot-pressing mold and a high-temperature furnace. The compressive strength of the hot-pressed briquettes was substantially improved and reached 436 N when the holding time period was 15 min, the hot-pressing temperature was 673 K, and the HyperCoal content, was 15wt%. Changes in the carbonaceous structure, as reflected by the intensity ratio between the Raman G- and D-bands (IG/ID), strongly affected the compressive strength of hot-pressed briquettes prepared at different hot-pressing temperatures. Compared with cold-pressed briquettes, hot-pressed briquettes have many advantages, including high compressive strength, low ash content, high moisture resistance, and good thermal stability; thus, we expect that hot-pressed briquettes will have broad application prospects.

Low-carbon operation, especially low-coke-rate operation, is very important for low CO2 emission in blast furnace ironmaking. Maintaining the permeability of the cohesive zone is required u...

Four types of coals, KL, XB, ZS and GD with different coal ranks, were dissolved with the organic solvent N-methyl-2-pyrrolidone at 350 °C and around 3.0 MPa pressure to obtain thermal soluble constituents (TSCs). The yield, component and maceral group were investigated as well as their coking properties, including caking index and thermoplasticity. The results indicated that the yields of the four coals were of the following order: KL > XB > ZS > GD. Based on the yield and the vitrinite content, coals were ranked from high to low. The ash contents of TSCs were significantly less than that of raw coals, and the TSCs contain more light components, leading to an increase in volatile matter. The patterns of Fourier transform infrared spectroscopy indicated that carbonyl was enriched in TSCs. Regarding the maceral group, TSCs were mainly composed of vitrinite which is the main reactive material and converts into binder phase in cokemaking process. Higher caking index values and fluidity were obtained in TSCs compared with the raw coals. The coking experiments with different amounts of TSCs addition were carried out. The results demonstrated that the proper TSCs addition could enhance the coke strength due to its high caking index and good fluidity.

Carbon dissolution from solid fuels used in a COREX gasifier was investigated in a high-temperature furnace to investigate the influences of temperature, carbon structure and ash properties of solid fuels into molten iron on carbon dissolution behavior. The results showed that the final carbon content of molten iron and dissolution reaction rate of carbon increased as the temperature increased. However, the dissolution behavior of different solid fuels varied with their properties. At the same temperature, the dissolution reaction rate of solid fuel from high to low was coke, semi-coke and lump coal. The apparent reaction rate constants of solid fuel were calculated using the piecewise fitting method based on the experimental data. The analyzed results showed that the dissolution rates of solid fuels had a good correlation with their microcrystalline structures. Moreover, the carbon crystallite structures of solid fuels used in COREX had greater influence on dissolution behavior than their ash properties.

The effect of MnO and CaO substitution for BaO on the viscosity and structure of CaO-SiO2-MgO-Al2O3-BaO-MnO slag was investigated using the rotating cylinder method and the structure was analyzed by employing FT-IR and XPS. The results showed that the viscosity at various temperatures decreased gradually when MnO content increased from 0wt% to 3wt%, and increased with BaO content rising from 0wt% to 5wt%, which was consistent with the corrected optical basicity (Λcorr). The activation energy for viscous flow (Eη) showed the similar trend. FT-IR and XPS spectra analysis indicated that both [SiO4]-tetrahedral and [AlO4]-tetrahedral were influenced by MnO and BaO content. The [SiO4]-tetrahedral and [AlO4]-tetrahedral network structures were depolymerized due to an increase in the relative fraction of free oxygen (O2−) and decrease of bridging oxygen (O0) with the increasing MnO content. As a larger amount of CaO was substituted by BaO, the trough depth of [SiO4]-tetrahedral and [AlO4]-tetrahedral bands became deeper, indicating the complexity of network structure and polymerization degree of slag increased, which led to an increase in viscosity.

Al2O3-SiC-SiO2-C composite refractories are interesting potential blast furnace hearth lining materials that feature several advantageous properties. In this study, the corrosion resistance of a novel Al2O3-SiC-SiO2-C composite refractory to blast furnace slag was investigated by adopting a rotating immersion method (25 r/min) at 1450–1550 °C and comparing it against a conventional corundum-based refractory at 1550 °C as a benchmark. The results showed that the apparent activation energy of Al2O3-SiC-SiO2-C composite refractory over the dissolution process in the slag is 150.4 kJ/mol. Dissolution of the Al2O3 and 3Al2O3·2SiO2 phases appeared to be the main cause of Al2O3-SiC-SiO2-C composite refractory corrosion. High-melting-point compounds in the slag layer formed a protective layer which mitigated the corrosion. The novel Al2O3-SiC-SiO2-C composite refractory is better suited to blast furnace hearth lining than the conventional corundum-based refractory, because the carbon phase and SiC phase in the material are not readily wetted by the blast furnace slag and therefore are more resistant to slag penetration. Higher melting point phases also may crystallize on the hot face of the hearth lining due to the high thermal conductivity of the Al2O3-SiC-SiO2-C composite refractory, promoting a more stable protective layer.

Al 2 O 3 -SiC-SiO 2 -C refractories are widely used as blast furnace hearth lining but have low oxidation resistance in the presence of CO 2 . Carbon composite brick is a newly developed Al 2 O 3 -SiC-SiO 2 -C refractory that may function better in the blast furnace hearth due to improved erosion-resistance and high thermal conductivity. In this study, the oxidation behavior and kinetics of carbon composite brick, carbon brick, and corundum brick were investigated in CO 2 atmosphere. The results show the oxidation resistance of carbon composite brick was better than that of carbon brick but worse than that of corundum brick. SiC functions as an antioxidant to play an important role in the oxidation process. For carbon composite brick, the oxidation activation energy was 141.72 kJ/mol at the step controlled by the interface reaction and 161.24 kJ/mol at the step controlled by gas diffusion. Carbon composite brick exhibits improved thermal conductivity and oxidation resistance relative to carbon brick and corundum brick that should allow improved performance in blast furnace hearth lining.

During blast furnace ironmaking, MgO flux is added to the sinter or pellets to reduce the viscosity and improve the desulfurization capacity of the slag. The distribution of total MgO addition between the sinter and pellets affects the interaction between the ferrous burdens. Inappropriate interaction between different burdens promotes the formation of an excessive amount of low-melting-point liquid phases, which reduces the permeability of the cohesive zone. In this study, the effect of MgO on the interaction between the sinter and pellets was visualized during heating and further investigated using thermodynamic calculations. A new concept named the distribution index of MgO was proposed for optimizing the MgO distribution between the sinter and pellets. A trade-off between the permeability and interaction between burdens in the cohesive zone was observed, which can be addressed by postponing the interaction between burdens to a higher temperature (i.e., a lower part of the cohesive zone).

The original version of this article unfortunately contained mistakes. Equation 1 and Tables 1 and 2 were incorrect. The corrected equation and tables are given below.

A novel process for boron enrichment and extraction from ludwigite based on iron nugget technology was proposed. The key steps of this novel process, which include boron and iron separation, crystallization of boron-rich slag, and elucidation of the boron extraction behavior of boron-rich slag by acid leaching, were performed at the laboratory. The results indicated that 95.7% of the total boron could be enriched into the slag phase, thereby forming a boron-rich slag during the iron and slag melting separation process. Suanite and kotoite were observed to be the boron-containing crystalline phases, and the boron extraction properties of the boron-rich slag depended on the amounts and grain sizes of these minerals. When the boron-rich slag was slowly cooled to 1100°C, the slag crystallized well and the efficiency of extraction of boron (EEB) of the slag was the highest observed in the present study. The boron extraction property of the slow-cooled boron-rich slag obtained in this study was much better than that of szaibelyite ore under the conditions of 80% of theoretical sulfuric acid amount, leaching time of 30 min, leaching temperature of 40°C, and liquid-to-solid ratio of 8 mL/g.

Al2O3–SiC–SiO2–C composites are widely used in ironmaking operations due to their favorable erosion-resistance. In the present paper, the oxidation behavior and kinetics of Al2O3–SiC–SiO2–C composites in air are investigated in terms of a theoretical analysis associated with the experimental data. Furthermore, the effects of temperature on the oxidation reaction are discussed. The results show that the oxidation of Al2O3–SiC–SiO2–C composites is mainly caused by atmospheric oxygen reacting with C and SiC in the materials. At 1200 °C, a protective layer can be found on the material surface due to the formation of the mullite phase. Predictions from the Chou model are in agreement with the experimental data. The characteristic oxidation time which indicates anti-oxidation properties for Al2O3–SiC–SiO2–C composites at 1000 °C and 1200 °C are 142.41 min and 264.89 min, respectively, indicating that the material at 1200 °C is more resistant to oxidation due to the formation of a protective layer on the surface.

Oxidation of carbon is one of the main problems in alumina–carbon based refractory. In this paper, the oxidation behaviors of novel carbon composite brick and traditional carbon brick were investigated by non-isothermal and isothermal experiments, and the samples after oxidation were examined by SEM and EDS analysis. The results show that the oxidation resistance of carbon composite brick is better than that of carbon brick. At 800−1200 °C, the oxidation kinetics of carbon brick follows the linear rate law, which belongs to non-protective oxidation, and the oxidation activation is 5586.76 J/mol. However, the oxidation kinetics of carbon composite brick follows the parabolic rate law, which belongs to protective oxidation. The compressive strength decreases with the increasing mass loss after oxidation due to the carbon loss, so for carbon composite brick which has less content of carbon the oxidation resistance is better than that of carbon brick. Furthermore, the existence of SiC in the surface of carbon composite brick is another reason for its good oxidation resistance.

Reduction of hematite pellets using H2-CO mixtures with a wide range of H2/CO by molar (1:0, 3:1, 1:1, 1:3, and 0:1) at different reducing temperatures (1073, 1173, and 1273 K) was conducted in a program reducing furnace. Based on an unreacted core model, the effective diffusion coefficient and reaction rate constant in several cases were determined, and then the rate-control step and transition were analyzed. In the results, the effective diffusion coefficient and reaction rate constant increase with the rise in temperature or hydrogen content. Reduction of iron oxide pellets using an H2-CO mixture is a compound control system; the reaction rate is dominated by chemical reaction at the very beginning, competition during the reduction process subsequently, and internal gas diffusion at the end. At low hydrogen content, increasing temperature takes the transition point of the rate-control step to a high reduction degree, but at high hydrogen content, the effect of temperature on the transition point weakens.

This study investigated the isothermal gasification reactivity of biomass char (BC) and coal char (CC) blended at mass ratios of 1:3, 1:1, and 3:1 via isothermal thermogravimetric analysis (TGA) at 900, 950, and 1000°C under CO2. With an increase in BC blending ratio, there were an increase in gasification rate and a shortening of gasification time. This could be attributed to the high specific surface area of BC and the high uniformity of carbon structures in CC when compared to those in BC. Three representative gas-solid kinetic models, namely, the volumetric model (VM), grain model (GM), and random pore model (RPM), were applied to describe the reaction behavior of the char. Among them, the RPM model was considered the best model to describe the reactivity of the char gasification reaction. The activation energy of BC and CC isothermal gasification as determined using the RPM model was found to be 126.7 kJ/mol and 210.2 kJ/mol, respectively. The activation energy was minimum (123.1 kJ/mol) for the BC blending ratio of 75%. Synergistic effect manifested at all mass ratios of the blended char, which increased with the gasification temperature.

The influences of the time, temperature and atmosphere on the reduction swelling of oxidized pellets were investigated by single factor experiments. The mechanisms of reduction swelling of oxidized pellets were analyzed and investigated by SEM (scanning electron microscopy) and XRD (X-ray diffractometer) analysis. The results show that the change rules of reduction swelling index of oxidized pellets in different reduction atmospheres are very similar. With the increase of reduction time, the reduction swelling index moves up firstly and then down. When the reduction temperature is above 900 °C, α-quartz turns into α-tridymite, and the transition generates additional volume expansion effect. The reduction swelling index changes faster in H2 atmosphere than in CO atmosphere. Increasing H2 content in the reduction atmosphere is useful to decrease the reduction swelling index, but it is also easy to cause oxidized pellets cracking.

The viscous behavior and potassium removal capacity of CaO–SiO2–8wt%MgO–17wt%Al2O3–2.5wt%BaO–K2O slag system with CaO/SiO2 of 1.07 were studied. The effect of K2O content ranging from 0 to 5 wt% on the viscosity, slag structure, apparent activation energy and potassium removal rate of present slag were analyzed. The results showed that with increase of K2O content in slag, the viscosity and apparent activation energy tended to increase. When adding K2O into the present slag, K+ ion rather than Ba2+ could preferentially compensate [AlO4] tetrahedron and more complex network structures would be formed, leading to higher polymerization degree of slag. The potassium removal rate was related to the reduction degree of K+ by carbon, and with rising of temperature and increasing of K2O content there was a decreasing trend for the potassium removal capacity of slag.

Four chars prepared from pulverized coals were subjected to non-isothermal and isothermal combustion tests in a thermogravimetric analysis (TGA) device. Three different test methods, i.e., non-isothermal single heating rate (A), non-isothermal multiple heating rate (B), and isothermal test (C), were conducted to calculate the kinetic parameters of combustion of coal char. The results show that the combustion characteristics of bituminous coal char is better than that of anthracite char, and both increase of heating rate and increase of combustion temperature can obviously improve combustion characteristics of coal char. Activation energies of coal char combustion calculated by different methods are different, with activation energies calculated by methods A, B and C in the range of 103. 12–153. 77, 93. 87–119. 26, and 46. 48–76. 68 kJ/mol, respectively. By using different methods, activation energy of anthracite char is always higher than that of bituminous coal char. In non-isothermal tests, with increase of combustion temperature, the combustion process changed from kinetic control to diffusion control. For isothermal combustion, the combustion process was kinetically controlled at temperature lower than 580 °C for bituminous coal char and at temperature lower than 630 °C for anthracite char.

In order to effectively utilize the high reactivity coke, the gasification characteristics of high and low reactivity cokes were investigated at 1100 °C. Low reactivity coke A and high reactivity coke B were chosen and charged into the reaction tube in two methods. The results indicated that the mass loss ratio of high reactivity coke in mixed cokes was more significant than that of single high reactivity coke in the middle stage of reaction. Nevertheless, the mass loss ratio of low reactivity coke in mixed cokes was less than that of single low reactivity coke. It was mainly attributed to gas diffusion and internal reaction of coke. When high and low reactivity cokes were mixed, the practical average mass loss ratio was nearly the same as the weighted average. The microscopic structures of coke indicated that with the increase of reaction time, the external and internal layers of low reactivity coke reacted more uniformly with CO2, whereas the reaction degree of external layer of high reactivity coke was obviously higher.

According to diferent energy utilization in diferent regions, blast furnace is divided into raceway zone, botom heat exchange zone (BHZ), thermal reserve zone (TRZ), and top heat exchange zone (THZ), and a mathematical model of nitrogen free blast furnace (NF-BF) is established. The optimum process parameters of two kinds of nitrogen free blast furnaces are calculated by the new mathematical model. The results show that for the nitrogen free blast furnace with a single row of tuyeres, the optimum process parameters are coke ratio of 220 kg/t, coal ratio of 193 kg/t, and volume of recycling top gas of 577 m3/t; for two rows of tuyeres, the process parameters are coke ratio of 202 kg/t, coal ratio of 211 kg/t, volume of recycling top gas in upper area of 296 m3/t, and volume of recycling top gas in lower area of 295 m3/t. Energy balances are reached in diferent regions. Theoretical combustion temperature (TCT) in raceway zone is largely afected by diferent processes, and a lower TCT should be adopted for the single row of tuyeres, but for two rows of tuyeres, a higher TCT should be maintained Compared with traditional blast furnace, in NF-BF, the emission of CO2 would be reduced by 45.91% and 49.02% for a single row of tuyeres and two rows of tuyeres, respectively, and combined with CO2 sequestration technology, zero emission of CO2 could be realized.

By using thermogravimetric analysis the process and mechanism of iron ore reduced by biomass char were investigated and compared with those reduced by coal and coke. It is found that biomass char has a higher reactivity. The increase of carbon-to-oxygen mole ratio (C/O) can lead to the enhancement of reaction rate and reduction fraction, but cannot change the temperature and trend of each reaction. The reaction temperature of hematite reduced by biomass char is at least 100 K lower than that reduced by coal and coke, the maximum reaction rate is 1.57 times as high as that of coal, and the final reaction fraction is much higher. Model calculation indicates that the use of burden composed of biomass char and iron ore for blast furnaces can probably decrease the temperature of the thermal reserve zone and reduce the CO equilibrium concentration.