Non-spherical Carbon Composite Agglomerates: Lab-scale Manufacture and Quality Assessment

Nakano, Masami; Naito, Masaaki; Higuchi, Kenichi; Morimoto, Koji

doi:10.2355/isijinternational.44.2079

Cited by 37 publications

(22 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Without the carrier gas, since the produced CO gas is difficult to be removed from the reaction site, the direct reductions of Reactions (5), (6) and (7) are somewhat inhibited. When the carrier gas flow rate is as large as 3.3ϫ10…”

Section: Effect Of Carrier Gas Flow Rate On Carbothermicmentioning

confidence: 99%

“…The non-spherical carbon composite agglomerates were also tired in a lab-scale manufacture for recycling steel work dust and improving blast furnace performance. 6) In addition to the new process development, the fundamental studies on the mechanism and kinetics of carbothermic reduction of iron oxide was energetically carried out for the carbon composite iron ore agglomerates. In a simultaneous reaction using a hematite-graphite facing pair, Kashiwaya et al 7) found the starting temperature of gasification decreased from 1 173 to 873 K in the facing pair under CO 2 atmosphere, and to 523 K under CO atmosphere due to the coupling phenomenon of reduction and gasification.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Mechanism of Carbothermic Reduction of Hematite in Hematite–Carbon Composite Pellets

2007

View full text Add to dashboard Cite

Isothermal reduction experiments are carried out to study carbothermic reduction of hematite in hematite-graphite composite pellets. The carbothermic reduction is dominated by the direct reduction at the initial stage of reduction, and it is determined by the indirect reduction together with the carbon solution loss reaction when the CO partial pressure exceeds a certain value, which is dependent on the temperature. The reduction is greatly promoted due to the increment of the contact area between the hematite and graphite particles and enhancement of heat conduction in the hematite-graphite composite pellets.The indirect reduction together with the carbon solution loss reaction is markedly activated with increasing temperature. At a moderate carrier gas flow rate, the carbothermic reduction rate reaches the highest value. The reduction can also be effectively improved with decreasing the graphite particle size.The relationship of reduction products, heating temperature and holding time has been obtained from the XRD analysis results at the different stages for various temperatures under the present experimental conditions. The SEM observation indicates that the indirect reduction together with the carbon solution loss reaction should dominate the carbothermic reduction of hematite at the later stage of reduction.

show abstract

Section: Effect Of Carrier Gas Flow Rate On Carbothermicmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanism of Carbothermic Reduction of Hematite in Hematite–Carbon Composite Pellets

2007

View full text Add to dashboard Cite

show abstract

“…[1][2][3] Under normal conditions cement is used as a binder to give the proper mechanical strength of the briquettes and then it goes to slag during the production of hot metal. [4][5][6] Coke and coal are the main sources of fuel and reducing agent in the blast furnace, at the same time they are responsible for the main fossil CO 2 emission in steel industry. Intensive work is being done to mitigate the CO 2 emissions in steel industry by partial substitution of fossil fuels (coal and coke) with renewable source of energy such as biomass.…”

Section: Introductionmentioning

confidence: 99%

Novel Approach Towards Biomass Lignin Utilization in Ironmaking Blast Furnace

2017

View full text Add to dashboard Cite

Growing concerns over fossil CO 2 emissions has created a considerable interest in an efficient utilization of renewable biomass in steel industry. Biomass lignin can be used as binder and reducing agent in the blast furnace briquettes. The traditional briquettes consist of various iron oxide-containing residues and cement is used as binder to give the proper mechanical strength. In the present study, cement (C) has been partially and totally substituted with lignin (L) to produce briquettes containing 0-12 wt.% lignin (L/C: 0, 10, 25, 50 and 100%). The mechanical strength has been evaluated based on drop test and tumbler index measurement. The partial replacement of cement with lignin up to 25% (3.0 wt.% lignin in briquettes) was exhibited adequate briquettes strength for blast furnace application. At higher substitution rate (L/C: 50 and 100%), the briquettes strength was sharply decreased. The briquettes with proper mechanical strength (L/C: 0, 10 and 25%) were subjected to self-reduction under inert atmosphere using thermogravimetric technique (TGA). The reduction rate of briquettes increased when increasing the cement substitution with lignin. The reduction took place in two main steps at 500-800°C and 800-940°C. Combined effect of gas diffusion and interfacial reaction were the rate determining step at the first stage while carbon gasification was controlling the second step of reduction. Interrupted reduction tests have been conducted to evaluate the compression strength after reduction. For all briquettes, the increased reduction temperature and lignin content deteriorated the briquette's mechanical strength due to the effect of dehydration and lignin gasification.

show abstract

“…Then a raw material forming fine iron ore particles and carbon material as briquette or pellet was proposed as a new feedstock of blast furnace. 2,[4][5][6][7] We call this new raw material "iron ore/carbon composite (IOC)" in this paper. Since the iron ore particles and the carbon material are in close contact in the IOC, the reduction rate of the iron ore particles is expected to be increased.…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Reduction Rate of Iron Ore by Utilizing Iron Ore/Carbon Composite Consisting of Fine Iron Ore Particles and Highly Thermoplastic Carbon Material

et al. 2011

View full text Add to dashboard Cite

Decreasing the thermal reserve zone temperature is believed to increase the energy efficiency of blast furnace iron-making. To do so, either the direct reduction reaction rate or the coke gasification reaction rate must be significantly increased below 1 000°C in CO-lean atmosphere. An iron ore/carbon composite (IOC) has been proposed as a new raw material that can enhance the reduction rate of iron ore. In this paper the possibility of the reduction rate enhancement was examined by preparing a kind of ideal IOC sample consisting of nano-sized Fe2O3 particles (10-70 nm in diameter) and a carbon material prepared from a thermoplastic resin. The nano-sized Fe2O3 particles in the IOC sample were surprisingly reduced to Fe in a few minutes at as low as 650°C in an inert atmosphere. This was realized by increasing the interfacial area between the Fe2O3 particles and carbon and by establishing intimate contact between the two. The carbon in the IOC sample was also completely gasified in less than 10 minutes at as low as 750°C in a CO2 atmosphere. The dramatic enhancement of the gasification rate was found to be realized by the enhancement of one of the direct reduction reactions, the reaction between Fe3O4 particles and carbon, by the aid of in-situ XRD measurement. This suggested that the enhancement of both the reduction reaction rate and the gasification reaction rate is realized by the same mechanism. These new findings will give a clue for designing IOC samples applicable to the blast furnace iron-making.KEY WORDS: iron ore/carbon composite; ultrafine Fe2O3 particles; thermoplastic carbon; in situ XRD; rapid reduction of iron ore.

show abstract

Non-spherical Carbon Composite Agglomerates: Lab-scale Manufacture and Quality Assessment

Cited by 37 publications

References 6 publications

Mechanism of Carbothermic Reduction of Hematite in Hematite–Carbon Composite Pellets

Mechanism of Carbothermic Reduction of Hematite in Hematite–Carbon Composite Pellets

Novel Approach Towards Biomass Lignin Utilization in Ironmaking Blast Furnace

Enhancement of Reduction Rate of Iron Ore by Utilizing Iron Ore/Carbon Composite Consisting of Fine Iron Ore Particles and Highly Thermoplastic Carbon Material

Contact Info

Product

Resources

About