Influence of TiO2 addition on the oxidation induration and reduction behavior of Hongge vanadium titanomagnetite pellets with simulated shaft furnace gases

Li, Wei; Wang, Nan; Fu, Guiqin; Chu, Mansheng; Zhu, Miaoyong

doi:10.1016/j.powtec.2017.12.050

Cited by 28 publications

(8 citation statements)

References 35 publications

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“…The softening–melting–dripping performance indexes were measured by the softening start temperature T 4 , the softening end temperature T 40 , melting temperature T s , dripping temperature T d , and pressure drop Δ P . Figure shows the effect of ABOFG on T 4 , T 40 , T s , T d , softening zone [ T 40 – T 4 ], melting–dripping zone [ T d – T s ], and the position distribution of softening–melting–dripping zone for different experimental conditions of HCVTM pellets.…”

Section: Resultsmentioning

confidence: 99%

“…In addition, T. Li et al studied the mineral elements' migration behaviors and the softening–melting properties of Ti‐bearing high‐basicity sinter. The study of W. Li et al investigated the oxidation induration of Hongge VTM pellets with different TiO 2 additions and its influence on subsequent reduction behavior with simulated shaft furnace gases. The research results of Cheng et al followed the present investigations that the dripping difficulty increased with the increasing TiO 2 contents.…”

Section: Introductionmentioning

confidence: 99%

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The Effect of Abandoned Basic Oxygen Furnace Gas Blowing on the Softening–Melting–Dripping Performance of Full High Cr‐Bearing Vanadia–Titania Magnetite Pellets

Song

Zhang

Cheng

et al. 2019

steel research int.

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It is inevitable to encounter increase in slag thickness, foaming slag, and high iron loss due to excessive formation of titanium carbonitride in blast furnace smelting of full high Cr‐bearing vanadia–titania magnetite (HCVTM). The effects of softening–smelting–dripping properties, the content variation of titanium carbonitride, and mineral element migration process of full HCVTM pellets with abandoned BOF gas (ABOFG) blowing are studied using X‐ray diffraction (XRD), X‐ray fluorescent (XRF), inductively coupled plasma‐atomic emission spectroscopy (ICP‐AES), X‐ray photoelectron spectroscopy (XPS), electron probe microanalysis‐wavelength‐dispersive spectrometer (EPMA‐WDS), and scanning electron microscope‐energy dispersive spectroscopy (SEM‐EDS). ABOFG is a type of neglected byproduct gas resource produced in the steelmaking process with high physical and chemical thermal energies and contains 20–40% CO, 20–30% CO2, 2–5% O2, and 30–50% N2. As the concentration of CO2 in ABOFG increases, the position and height of the cohesive zone decline, and the concentration of titanium carbonitride decreases from 1.424% to 1.035%, which are beneficial to the BF smelting process. In addition, the migration processes of Ti, V, and Cr are also affected, especially Ti tends to enrich in the dripped slag, whereas V and Cr tend to concentrate at the dripped iron.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Effect of Abandoned Basic Oxygen Furnace Gas Blowing on the Softening–Melting–Dripping Performance of Full High Cr‐Bearing Vanadia–Titania Magnetite Pellets

Song

Zhang

Cheng

et al. 2019

steel research int.

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“…It can be surmised that the viscosity of the RS is increased due to the decrease in the content of titanium carbonitride in the residual slag, which reduces the amount of residue and iron loss in the softeningÀmelting zone. [12,23,24] In other words, the injection of ABOFG can make the effect of a slagÀiron separation better. The coke's role in the blast furnace includes charge holder, reducing agent, heating agent, and carbon source.…”

Section: The Slagàiron Separation Effect and Compressive Strength Changes Of Cokementioning

confidence: 99%

Physicochemical Phenomena of CO₂ Injection in Polymetallic Ironmaking

Song

Zhang

Gao

et al. 2021

steel research int.

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Abandoned basic oxygen furnace gas (ABOFG) is a kind of byproduct fuel resource produced in the basic oxygen furnace (BOF) steelmaking process with a high temperature of 1773-1873 K and 20-40% (vol.%) CO and 20-30% (vol.%) CO 2 and is usually ignited and discharged as waste gas (34.7% abandoned rate). The effects and physicochemical phenomena of injecting CO 2 -containing ABOFG into high-Cr-bearing vanadiaÀtitania magnetite ironmaking are investigated. The thermodynamic calculation shows that the ABOFG injection changes the gas partial pressure and the oxygen potential in the slagÀcoke interfaces and suppresses the titanium carbonitride formation. According to the results of soft-eningÀmeltingÀdripping experiments, the content of titanium carbonitride in the high-titanium slag decreases from 2.53% to 1.14% as the CO 2 content in ABOFG increases from 0 to 30%, which is conducive to improving the high-temperature physicochemical properties of molten slag. The recoveries of vanadium and chromium are also improved with the decrease in iron loss. Moreover, the residual coke still maintains a considerable compressive strength with a slight effect from ABOFG injection, which is expected to reduce carbon consumption.

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“…As a result, the reduction of the titanomagnetite ores by H2 has the fastest rate. In addition H2 gas does not cause carburization of the reduced iron ores, but this is observed in studies that have used CO or CH4 as the reducing agent [19], [143], [151], [152].…”

Section: Ch4mentioning

confidence: 99%

Reduction of New Zealand Titanomagnetite Ironsand pellets in H2 Gas at High Temperatures

Zhang¹

2021

Preprint

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To reduce the emission of carbon dioxide (CO2) from industrial ironmaking in New Zealand (NZ), it is proposed to perform direct reduction (DR) of NZ titanomagnetite ironsand pellets using H2 gas. In this thesis, the H2 reduction behaviour of pellets made from the NZ ironsand are examined. The aim of the thesis is to understand the reduction mechanism, and develop an analytical kinetic model to describe the reduction progress with time. This has been addressed through a series of reduction experiments in H2 gas. The overall reduction kinetics are examined in a Thermogravimetric analysis system (TGA); the phase evolution during reduction is measured by an in-situ neutron diffraction (ND) method; and the evolution of pellet- and particle-scale morphologies are analysed by scanning electron microscopy (SEM) of quenched samples. Based on the analysis of results from these experiments, the mechanism of the reduction is found to be adequately described by a single interface shrinking core model (SCM). Two different types of pellet are considered in this work: Ar-sintered pellets were sintered in an inert atmosphere to produce pellets containing mainly titanomagnetite (TTM). Pre-oxidised pellets were sintered in air to produce pellets containing mainly titanohematite (TTH). The reduction rate of both types of pellets is found to increase with reduction temperature, H2 gas flow rate, and H2 gas concentration. Above 1143 K, it is found that both types of pellets present a similar reduction rate, while below 1143 K, the reduction of pre-oxidised pellets is much faster than that of Ar-sintered pellets. For both pellets, the maximum reduction degree can reach ~97%. After complete reduction, metallic Fe coexists with other unreduced Fe-Ti-O phases (FeTiO3, TiO2 or pseudobrookite (PSB)/ferro-PSB), which is consistent with the observed reduction degree of < 100%. During reduction of both types of pellets, any TTH present is rapidly reduced first. After this step, TTM is then reduced to FeO, with Ti becoming enriched in the remaining unreduced TTM. FeO is further reduced to metallic Fe, which makes up to ~90% reduction degree. Eventually Ti-enrichment of the TTM leads to a change in the reduction pathway and it instead directly converts to metallic Fe and FeTiO3. Above ~90% reduction degree, reduction of the remaining Fe-Ti-O phases occurs (leading to the formation of TiO2 or PSB/ferro-PSB). The enrichment of Ti in TTM which accompanies the generation of FeO is substantially different from conventional non-titaniferous ores. This enrichment is confirmed by EDS-maps of the particles and stoichiometric calculations of the molar fraction Ti within the TTM phase. This enrichment effect changes the morphology of FeO in the particles, leading to the formation of FeO channels surrounded by Ti-enriched TTM. At the pellet-scale, both types of pellets present a single interface shrinking core phenomenon at higher temperatures. Metallic Fe is generated from pellet surface with a reaction interface moving inwards. However, at lower temperatures this pellet-scale interface becomes less defined in the pellets. Instead, particle-scale reaction fronts are observed. A single interface shrinking core model (SCM) is shown to successfully describe the reduction of pellets for reduction degrees < ~90% at all temperatures studied. However, at reduction degrees > ~90% this model fails. This is attributed to the change in reaction mechanism required to reduce the residual Fe-Ti-O phases that remain dispersed throughout the whole pellet at this stage of the reaction. The single interface SCM indicates that the reduction rate of the Ar-sintered pellets is controlled by the interfacial chemical reaction rate. However, two different temperature regimes are identified. Above 1193 K, the activation energy is calculated to be 41 ± 1 kJ/mol, but below 1193 K the calculated activation energy increases to 89 ± 5 kJ/mol. This change in activation energy appears to be associated with the change of the rate-limiting reaction from FeO → metallic Fe to TTM → FeO. By contrast, the pre-oxidised pellets exhibit mixed control at 1043 K, where a role is played by both the interfacial chemical reaction rate and the diffusion rate through the outer product layer. However, at temperatures of 1143 K and above, the pre-oxidised pellets also exhibit interfacial chemical reaction control, with a single activation energy of 31 ± 1 kJ/mol, which again seems to be consistent the rate-limiting reaction being FeO → metallic Fe. In summary, the findings in this thesis contribute to understanding of the reduction of NZ ironsand pellets in H2 gas, and establish a kinetic model to describe this process. In the future, this information will be applied to develop a prototype H2-DRI shaft reactor for NZ ironsand pellets.

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Influence of TiO2 addition on the oxidation induration and reduction behavior of Hongge vanadium titanomagnetite pellets with simulated shaft furnace gases

Cited by 28 publications

References 35 publications

The Effect of Abandoned Basic Oxygen Furnace Gas Blowing on the Softening–Melting–Dripping Performance of Full High Cr‐Bearing Vanadia–Titania Magnetite Pellets

The Effect of Abandoned Basic Oxygen Furnace Gas Blowing on the Softening–Melting–Dripping Performance of Full High Cr‐Bearing Vanadia–Titania Magnetite Pellets

Physicochemical Phenomena of CO₂ Injection in Polymetallic Ironmaking

Reduction of New Zealand Titanomagnetite Ironsand pellets in H2 Gas at High Temperatures

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Influence of TiO2 addition on the oxidation induration and reduction behavior of Hongge vanadium titanomagnetite pellets with simulated shaft furnace gases

Cited by 28 publications

References 35 publications

The Effect of Abandoned Basic Oxygen Furnace Gas Blowing on the Softening–Melting–Dripping Performance of Full High Cr‐Bearing Vanadia–Titania Magnetite Pellets

The Effect of Abandoned Basic Oxygen Furnace Gas Blowing on the Softening–Melting–Dripping Performance of Full High Cr‐Bearing Vanadia–Titania Magnetite Pellets

Physicochemical Phenomena of CO2 Injection in Polymetallic Ironmaking

Reduction of New Zealand Titanomagnetite Ironsand pellets in H2 Gas at High Temperatures

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Product

Resources

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Physicochemical Phenomena of CO₂ Injection in Polymetallic Ironmaking