Ryo Inoue

• Tohoku University

In Japan, approximately 14 million tons of steelmaking slag were generated in FY2023. Owing to its excellent mechanical properties, steelmaking slag has been primarily used in construction materials, such as roadbeds. However, these applications are predicted to decrease, making it necessary to find new ways to utilize the slag. Steelmaking slag co...

When using steel scraps containing Cr and Mn as raw materials in electric arc furnace (EAF) steelmaking, EAF steelmaking slag containing Cr2O3 and MnO is inevitably produced as a by-product. Since Cr and Mn are valuable elements, it is economically and environmentally important to recover by reduction of EAF slag and reuse those elements into steel...

The quality of iron ore is expected to change, and blast furnace raw materials will diversify in the future as ores are pretreated to improve ore quality. Furthermore, an increase in the proportion of hydrogen-based reducing agents is necessary to satisfy the demand for carbon neutrality. Therefore, the capacity of blast furnace operations to adapt...

Steelmaking slag contains a considerable amount of phosphorus, which is widely used in human society. Phosphorus recovered from steelmaking slag will provide a new resource, and reusing the steelmaking slag, from which phosphorus has been removed, in the steel manufacturing process reduces the total slag volume. In this study, phosphorus was separa...

To improve the stability of hydrogen-enriched reduction operations in blast furnaces, it is necessary to maintain gas permeability in the cohesive zone. The reduced and produced metallic iron phases contribute to the strength of the iron ore in the cohesive zone. However, the form of the iron produced and its evaluation method have not been establi...

Since it has been urgently demanded to secure the secondary phosphorus resources domestically in addition to the establishment of a stable supplying path of phosphate ore from overseas, the recovery of phosphorus from steelmaking slags is attracting attention. The phosphorus-enriched slag obtained by dephosphorizing the high phosphorus hot metal, w...

The recovery rate of iron is reduced if iron particles suspended in the refining slag do not sediment. The sedimentation rate of particle iron in the foaming slag is slower than in the slag in the single-phase liquid. Iron particles are especially likely to remain in the foaming slag. To predict the sedimentation rate of iron particles in the slag,...

The recovery rate of iron is reduced if iron particles suspended in the refining slag do not sediment. The sedimentation rate of particle iron in the foaming slag is slower than in the slag in the single-phase liquid. Iron particles are especially likely to remain in the foaming slag. To predict the sedimentation rate of iron particles in the slag,...

Since 10 million tons of steelmaking slag, which contains a few percent of phosphorus, are annually produced, the phosphorus amount in the slag is equivalent to the annual import volume of phosphorus rock in Japan. Therefore, the steelmaking slag is attracting attention as a potential phosphorus resources. Phosphorus-concentrated slag obtained by t...

It is important to clarify the behavior of elements in the reaction between molten CaO–SiO 2 –Fe t O–Al 2 O 3 slag and liquid metal during the remelting of Cu scrap. To estimate the desirable slag composition for retaining Sn in metal, the effects of the slag basicity and the concentrations of Fe t O and Al 2 O 3 on the SnO activity coefficient wer...

Since it has been urgently demanded to secure the secondary phosphorus resources domestically in addition to the establishment of a stable supplying path of phosphate ore from overseas, the recovery of phosphorus from steelmaking slags is attracting attention. The phosphorus-enriched slag obtained by dephosphorizing the high phosphorus hot metal, w...

The hold‐up of molten pig iron and slag melt in the coke packed bed of blast furnace (BF) causes a decrease of void between coke lumps and inhibits gas permeability. Smooth dripping of those liquids in the coke bed is desirable to keep the productivity of BF. Herein, the conditions for smooth flowing of molten iron on coke surface are calrified, an...

It is expected that phosphorus-concentrated slag produced by using the pyro-reaction between high phosphorus hot metal, which was prepared by the reduction of usual steelmaking slag with a small amount of hot metal, and oxidizing slag can become an important phosphorus resource instead of phosphate rock. For separating phosphorus from the phosphoru...

Since 10 million tons of steelmaking slag, which contains a few percent of phosphorus, are annually produced, the phosphorus amount in the slag is equivalent to the annual import volume of phosphorus rock in Japan. Therefore, the steelmaking slag is attracting attention as a potential phosphorus resources. Phosphorus-concentrated slag obtained by t...

Steelmaking slags are reused for civil engineering and roadbed materials. When the slag containing Cr oxide is reused, there is a slight case of toxic Cr⁶⁺ elution from the mineral phase containing CrO3 into the environment. Therefore, in order to effectively utilize slag as resources, the development of a technology to suppress Cr elution is urgen...

The conventional recovery technology is not economically viable due to the low rare metal concentration in industrial scraps. It is expected that iron- and steelmaking process can recover rare metals as a high-concentration ore substitute. For efficient enrichment of rare earth metal (REM) in this process, the establishment of the thermodynamic val...

Iron droplet that entrapped in the refining slag reduces the yield of iron, so it is necessary to accurately estimate the settling rate of iron particle in the slag. However, since slag is a solid-liquid coexisting fluid, the sedimentation rate of iron particle cannot be derived even using the Stokes’ equation based on the viscosity of the liquid p...

The expansion phenomenon, which is a major issue when using steelmaking slag as a roadbed material and civil engineering material, is caused by the volume expansion during hydration of free CaO (undissolved CaO and precipitated CaO) and free MgO (undissolved MgO and precipitated MgO) contained in steelmaking slag. From the weight change of MgO reag...

During the mass recycling of spent lithium-ion battery (LIB) packs, the packs that have not been disassembled are heat-treated to remove organic substances; further, the valuable metals obtained in the burnt product are recovered in the leaching process. Numerous methods have been reported for the efficient recovery of valuable metals in the leachi...

The refractory lining in a furnace is always damaged and peels off when spent lithium-ion secondary batteries (LIB) are pyro-processed in a rotary kiln. To develop highly durable refractories and to elucidate the erosion behavior, various analyses such as scanning electron microscopy/energy dispersive X-ray spectroscopy, laser-induced breakdown spe...

Purpose: In present work, the mineral phases in chromium-containing slags were identified, and the formation mechanisms of Cr(VI) in Cr2O3-containing mineral phases were discussed. Design/methodology/approach: In steelmaking slag containing chromium, chromium is mainly present as spinel phases such as MgCr2O4 and (Mg,Fe)Cr2O4. When these Cr(III) ox...

Chromium is an essential element which contributes to our life activity. However, since the hexavalent chromium causes health damage, its content in water is strictly limited below 0.05 mg/L as the aqueous and soil environment standard values in Japan. The development of high-efficient stabilization method of the steelmaking slags containing chromi...

Owing to powder accumulation in the packed bed, the permeability of gas and liquid deteriorates, which decrease throughput of the blast furnace. Powder in the moving bed has a large effect on the productivity and efficiency of the blast furnace process when operating with low coke rate and using high-reactivity coke. Therefore, an investigation on...

To mitigate CO2 emission from a blast furnace, the use of H2 as a reducing agent is considered to be a prominent method. Reduction of iron ore was reported to be improved by H2 addition. In the present research, reduction in a sinter-packed bed by CO and H2 was carried out under various oxygen partial pressures, and the influence of reduction atmos...

Clusters of Al2O3 inclusions in a liquid stainless steel (18/8) and in a clogged ZrO2 nozzle after casting were studied during a pilot plant trial. Samples were taken from the melt at different holding times after an addition of 0.1 mass% Al. The characteristics (composition, size, number, and morphology) of clusters and clustered inclusions in the...

In ironmaking high temperature processes, solid, liquid, and gas phases coexist and interact one another. The gas flow in a packed bed containing liquid and powder depends on their distributions, and the packing structure. Some parts of the liquid and powder phases passing through of the packed bed accumulate. Excessive accumulation may clog the ga...

With the aim to decrease the reducing agent rate in blast furnace, the use of ferro coke containing metallic iron as a catalyst was proposed. This new burden material is expected to lower thermal reserve zone temperature. For the production of ferro coke, the use of a vertical coke oven is examined to realize the optimum carbonizing process. In thi...

In Japan, 15 million tons of steelmaking slag is produced annually as a by-product of the steelmaking process. It is known that steelmaking slag has specific properties to decrease hydrogen sulfide in seawater. To date, however, the specific mechanism is still unknown. This is the first report that explains the process of the slag reducing the hydr...

The characterization of nonmetallic inclusions is of importance for the production of clean steel in order to improve the mechanical properties. In this respect, a three-dimensional (3D) investigation is considered to be useful for an accurate evaluation of size, number, morphology of inclusions, and elementary distribution in each inclusion partic...

The estimation of fine inclusion particles is required in order to clarify its effect on the miniaturization of steel grain. In this study, the stability of ZrO2, Ti2O3, TiAl2O5, Ce2O3, and CeS particles during extraction was examined using acid, halogen-methanol, and nonaqueous electrolytes. ZrO2, Ti2O3, and TiAl2O5 particles hardly dissolved in 4...

Reduction of the reducing agent aiming at the mitigation of carbon dioxide emissions decreases the gas permeability in blast furnace. Favorable control of burden distribution and optimization of packed bed might mitigate decreasing permeability. Especially, decreasing thickness of cohesive zone would be effective. In present study, the influence of...

A low coke rate operation in blast furnace is desired to decrease the carbon input and mitigate global warming problem. However, low coke rate operation tends to cause the gas permeability to deteriorate. The mixing of small-size coke (nut coke) including high reactivity coke in ore layer is considered to be a promising way to improve permeability...

To decrease the reducing agent ratio in the blast furnace, various measures such as mixed charging are being pursued. Coke mixed charging is considered to improve permeability in the cohesive zone and the reducing behavior of ore particles. Conventionally, these researches were frequently carried out with a small packed bed. However, the informatio...

The liquid dripping under the cohesive zone influences gas flow and permeability in the lower part of the blast furnace, and it is closely related to blast furnace productivity and operational stability. Especially, liquid distribution and hold-up in the coke packed bed can be mentioned as important phenomena regarding the liquid dripping. Although...

The ratio of equiaxed grains on a cross section and the size of equiaxed grains in a Fe-20 mass% Cr alloy deoxidised with Ti/M (M = Zr or Ce) were studied as function of nitrogen content and particle characteristics such as size distribution, morphology and composition. Fe-20 mass% Cr alloys were melted at 1 600 degrees C, deoxidised, and cooled to...

The effect of TiN crystallization on the solidification structure of Ti-added ferritic stainless steel were studied in Ti/Mg, Ti/Ca, Ti/Mg/Al, Ti/Ca/Al, Al/Ti/Ca and Ti/Mg(Ca)/Ca(Mg) deoxidations carried out at 1 600 degrees C using an Fe-17.5(11)%Cr-0.25%Mn-0.20%Si-0.2 to 0.3%Ti-0.01%C-0.003 to 0.04% N alloy on a mass percent basis. Compositional...

Low reducing agent operation of the blast furnace has an important role in mitigating carbon dioxide emissions in the steel works. Low reducing agent operation results in a low coke rate in the blast furnace. In low coke rate operation, the permeability in the blast furnace is considered to change remarkably due to the increase in the ore-to-coke (...

The liquid flow in the packed bed strongly affects the productivity and operational stability of the blast furnace. It is controlled by the physical properties and wettability of the melt and the structure of the packed bed. However, this is a difficult object of analysis, as melt properties and conditions in the furnace are inhomogeneous. In this...

For the sake of reduction of reducing agent in blast furnace, the use of ferro coke containing metallic iron as a catalyst was proposed to control the thermal reserve zone temperature. To produce ferro coke, the vertical type of coke oven is used to realize the optimum carbonizing process. In the vertical type coke oven, it is estimated that each p...

Single (Ti and Mg) and multiple (Ti/M: M=Mg, Ca, Zr or Ce and Ti/M/M': Ti/Mg/Al, Al/Mg/Ti, Al/Ti/Ca, Ti/ Al(Ca)/Ca(Al), Ti/Mg(Ca)/Ca(Mg), Ti/Zr/Ca(Mg) or Ti/Ce/(Ca) deoxidations were carried out at 1 600°C to study the effect of TiN crystallization on the solidification structure in an Fe-17.5(11)%Cr-0.25%Mn-0.20%Si-0.2 to 0.3%Ti-0.01%C alloy conta...

To realize CO 2 capture and storage, many methods for CO 2 sequestration should be investigated from a long-term viewpoint. The development of novel CO 2 absorbent material is considered to be a candidate for the effective CO 2 sequestration. Investigation of CO 2 absorbent material is usually based on the experiment with following thermodynamic an...

Low reducing agent operation of large blast furnace has attracted a special attention from the background of the global warming. Because the coke ratio is reduced in this operation, causing a huge local ventilation resistance that causes operational problems, it has become increasingly necessary to understand the operation of blast furnace based on...

Since the cohesive zone has a great influence on the gas flow in the blast furnace, modeling of the cohesive zone is considered to be an important subject. In the cohesive zone, the softening and melting behavior of ore particles is affected by the load from the upper layer and the temperature distribution, and the pressure drop of the ore layer in...

Currently in Japan, 15 million tons of steelmaking slag as a by-product of the steelmaking process is produced annually. More than 60% of the steelmaking slag is used in civil construction. steelmaking slag has special properties which are presently under-exploited. Therefore, research into the greater utilization of the special characteristics of...

Wettability of a solid by a liquid plays a key role in achieving the purpose of the process in moving bed-type reactors. In recent years, particle method has been proposed for the design of processes which include multiphase flows. Using this method, it is possible to analyze a free surface flow without explicitly tracking the interface. Although s...

In order to improve the process control during the steelmaking process, it is essential to obtain knowledge, as well as interpret information, on the characteristics of non-metallic inclusions in liquid steel samples. The purpose of the present study is to evaluate the effect of different sampling conditions on the inclusion characteristics. The ch...

Some aspects for the application of Laser Ablation-Inductively Coupled Plasma Mass Spectrometry (LAICP- MS) are considered and discussed from the viewpoint of the rapid analysis of oxide inclusions in metal samples. The inclusion characteristics in Fe-10% Ni alloy samples such as number, size and particle size distribution obtained by LA-ICP-MS met...

Extraction of inclusion particles from a metal matrix allows for accurate three-dimensional estimation of their morphology, size, and composition. In this study, the stability of MgO and MgAl 2O 4 particles was examined using acid, halogen-methanol, and nonaqueous electrolytes. These particles hardly dissolved in a 2% TEA-Ba (2 v/v% triethanolamine...

Supply of Fe ions is considered to be effective for the growth of kelp (a kind of seaweed). In the present research, a demonstration experiment in which seaweed beds/shoals were formed using a mixture of steelmaking slag and dredged soil was carried out in a marine area of Kawasaki City, Japan. The average strength of the mound for seaweed beds, wh...

Shaft gas injection of reducing gas in the blast furnace is one of favorable ways to greatly decrease CO2 emissions from steel works, and this approach is used for the top gas recycling and oxygen blast furnace processes. In these processes, the penetration effect of the gas injected from the auxiliary tuyeres is important for attaining effective g...

Increased reactivity of the reducing agent is desired for the blast furnace operation with a low reducing agent. In the present study, the catalytic effects of iron, calcium oxide, and a multi component oxide melt on the gasification reaction of reducing agent were investigated. The addition of Fe, and CaO enhanced the gasification reaction. The ca...

Blast furnace technology is currently aiming at low reducing agent operation so as to decrease CO2 emissions. At the same time, the inner volume of blast furnaces has frequently been enlarged so as to increase production rate in some countries, including Japan. Operating conditions designed for low reducing agent in a large blast furnace tend to ca...

The microstructure and toughness in Fe–0.04%C–1.85%Mn–0.03%Si–0.018%Nb steel deoxidized with Ti and Zr have been studied as functions of particle characteristics, austenite grain size and soluble Ti and Zr contents using a simulated HAZ (heat affected zone) thermal cycle (peak temperature, 1400°C; peak holding time, 60 s; time of cooling from 800 t...

Some rare metal elements such as Mn, Nb and V are contained along with P in iron ore. As a resource strategy in Japan, the possibility of efficient recovery of these elements as byproducts of steel in conventional iron and steelmaking processes has been discussed. It was clarified that rare metals can be easily transferred to molten pig iron in a b...

As an initial stage of the creation of a new solid material for carbon dioxide capture and storage (CCS), the behaviors of CO2 absorption and desorption were investigated in terms of Li2O-TiO2 compounds. The LiTiO4 specimen began to absorb CO2 at 250°C with the formation of Li2TiO3 and Li 2CO3 phases. The absorption rate was significantly enhanced...

In order to mitigate CO2 emissions from steel industry, decreasing coke rate by shaft gas injection such as top gas recycling is a favorable way. The conception based on oxygen blast furnace is able to bring several profits for intensifying gas reduction and decreasing coke rate by massive coal injection. In these processes, gas injection from auxi...

Low reducing agent operation of the blast furnace is an essential method for mitigating CO(2) emissions in ironmaking. Because the coke rate is reduced in low reducing agent operation, gas permeability tends to deteriorate. Recently, blast furnaces with inner volume larger than 5 000 m(3) have become usual not only in Japan, but also in other Asian...

Carbon capture and storage (CCS) is a key technology for greatly reducing CO, emissions in the long term, and therefore a low-energy CCS process needs to be developed. This study focused on the solid absorption process using basic oxide, and thermodynamically examined the carbonation abilities of various basic oxides and compounds containing CaO, B...

Since the enlargement of blast furnace inner volume is generally carried out two dimensionally, the diameter of the throat, bosh and hearth increase with the inner volume, while the height is kept approximately constant. Due to these changes, blast furnace enlargement influences burden descending behavior and stress distribution in the furnace. The...

Recently, discrete element method (DEM) had been applied for simulation of the blast furnace. For mitigating computation load and precise simulation of blast furnace, the determination of optimum physical parameters in DEM are very important. In the present study, influence of variation of hardness, rolling friction coefficient of particle and desc...

The present investigation intends to elucidate the transient behavior of burden descending, the influence of cohesive zone shape on the solid flow and the stress field through three-dimensional analysis by discrete element method (DEM) in blast furnace. Although many continuum models were developed to analyze the in-furnace phenomena such as solid...

Increasing reactivity of burden for the blast furnace can decrease temperature of the thermal reserve zone and reducing agent for producing pig iron. Carbon iron ore composite is considered to be a candidate of high reactive burden. Reactivity of the carbon iron ore composite can be improved by an increase in reactivity of carbon. It is known that...

Since the solid flow in blast furnace is composed of each particle motion, the discontinuous phenomena of burden descending can be occasionally observed. Understanding of the solid flow is important for blast furnace operation. Discrete Element Method (DEM) can offer the behavior for each particle of burden in the furnace. Three dimensional analysi...

Synopsis : Application of discrete element method (DEM) to blast furnace attracts special interest, because the accurate solid motion analysis in the blast furnace is feasible by DEM. In the previous studies in this area, although the descending velocity and physical parameters of particle in DEM were important factors for accurate solid motion ana...

Production of Fe-Mn alloy from the slag generated in the Mn-removal treatment of cast iron was investigated by using the method of carbon reduction of FeO-Si02-MnO and FeO-Si02-MnO-CaO slags at 1 723 K. In the first stage, almost all the Fe was reduced from the slags, followed by the reduction of Si and Mn Finally, Fe-Mn-Si metal was obtained as a...

Enhancement of reactivity of the burden in the blast furnace can decrease the reducing agent of blast furnace. Besides high reactivity coke, the carbon iron ore composite is considered to be a typical high reactivity burden that can control the thermal reserve zone temperature. Since the reactivity of biomass char is much higher than that of coke,...

Reduction of Green House Gases is an important issue. Steel industry is actively making an effort to reduce carbon dioxide emission. Biomass can be considered as a carbon neutral material and would be an alternative energy for ironmaking. In the present study, optimum biomass utilization in ironmaking process is studied for reducing carbon dioxide...

Japanese steel industry has been promoting significant efforts to decrease CO2 emissions, in addition to the active introduction of a lot of energy-saving processes in the past. Energy saving systems like CDQ in coke oven and TRT in blast furnace have been perfectly introduced into the steel works. The inner volume of the blast furnace in Japan was...

In Japan, blast furnace operating is currently aiming at low reducing agent to decrease carbon dioxide emission from steel works. Moreover, the inner volume of the blast furnace has been frequently enlarged over 5000m3 at the relining. In such a condition, discontinuous and instable phenomena in furnace have been actualized. The precise control of...

Analysis of solid motion in the vicinity of raceway of the blast furnace has been carried out by discrete element method (DEM). The physical properties of particle for DEM calculation are important factors to simulate precisely the solid motion in the blast furnace. In order to represent the feature of burden such as coke in the lower part of the b...

Decreasing the carbon dioxide emission from steel industries is an important issue. It is considered that due to the high reactivity of carbon iron ore composite, it can control the thermal reserve zone temperature and decrease the consumption of reducing agents in blast furnace. In the present study, a reaction model of the carbon iron ore composi...

The particle characteristics such as size distribution, composition and morphology have been studied in an Fe-20mass%Cr alloy as a function of holding time at 1600°C. The alloy was deoxidised with Ti and Ce, followed by holding at 1600°C and cooling to 1400°C and quenching. The inclusion particles were investigated on a surface of film filter with...

Laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) has been used for the determination of the composition and size of oxide particles consisting of SiO2, MnO, Al2O3, MgO and CaO on the surface of a glass or metal sample. The composition and size of multicomponent oxide particles such as MnO-SiO2, CaO-Al2O3 and CaO-Al2O3-MgO eva...

Synopsis : Decrease of carbon dioxide emission is a serious subject in the steel industry. Although low reducing agent operation of blast furnace is a primary method in ironmaking, many different ways should be taken. Utilization of biomass as a carbon-neutral reducing agent is an attractive one for ironmaking. However, since the calorific value is...

Thermodynamics of Zr deoxidation equilibrium in liquid iron has been studied at 1 873 K by using ZrO(2)-9mol% MgO and mullite (3Al(2)O(3)center dot 2SiO(2)) electrolytes coupled with the quantitative alalysis of soluble Zr and insoluble Zr as ZrO(2) by using a potentiostatic electronic extraction method. The soluble 0 content for a given soluble Zr...

In order to clarify the effect of non-uniformly dispersed TiN particles on the inhibition of austenite grain growth at non-steady state, an Fe–1.5%Mn–0.12%Ti–Si(<1.1%)–N(20~130 ppm)–C(0.05 and 0.15%) alloy with and without Mg deoxidation has been cooled from 1873 to 1473 K at 50 or 5 K·min−1, followed by quenching. The austenite grain size distribu...

The crystallization and precipitation of TiC and ZrC in an Fe-0.05 similar to 0.30%C alloy have been studied from the measurement of particles located at interdendritic region and austenite grain boundaries. The particles and gamma grains were observed with the samples quenched at 1673-1743 K and those for holding at 1673 K for 0-180 min. In an Fe-...

Deoxiclation experiments using Ti, Pr and Ti/Pr have been conducted using a Fe-10mass% alloy at 1 600 degrees C. The purpose of the experiments was to study the change of particle size distribution as functions of holding time, difference between the different deoxidation procedures, and amount of deoxiclant added. The Fe-10%Ni alloy was melted in...

A direct combustion method of automobile shredder residue at high temperature is considered to be an effective process, because the volume of residue can be reduced and many valuable metals can be recovered. However, the fly ash containing large amounts of heavy metals and fluorine are generated inevitably by this process. Therefore, the treatment...

It is legally demanded that the wastes containing asbestos should be change to harmless substances completely due to the harmful effects of asbestos fiber on health. The purpose of present research was to construct a safe, reliable and facile technique by using mechano-chemical reaction, which is a non-combustion process and operated in a closed sy...

The inhibition effect of inclusion particles and soluble elements on the austenite grain growth has been studied in Fe-0.05% C and Fe-10% Ni alloys deoxidized by Mn (1.0%) - Si (0.2%), Ti (0.05%), Mg (0.10%), Zr (0.08%) or Ce (0.12%). It is found experimentally that total surface area of grains per unit volume, which is in inverse proportion to the...

The behavior of phosphorous transfer from P2O5-containing CaO-SiO2-FetO slags to 2CaO center dot SiO2 particles homogeneously dispersed in slag has been studied by using a microprobe analysis. The maximum phosphorus distribution ratio between 2CaO center dot SiO2 particle and slag is obtained at the nose composition of 2CaO center dot SiO2 primary...

Dephosphorization of a liquid Fe-5mass%P alloy with a solid-liquid coexisting flux in which 2CaO center dot SiO2 particles (20 to 50 mu m) are uniformly dispersed in CaO-SiO2-FetO slags has been studied at 1 400 degrees C. For the slag with high SiO2 and low T.Fe contents, the change of slag composition is small and the fraction of 2CaO center dot...