A comparative study for smelting of chromite ore, pellets, briquettes and sinter

Pal, Jagannath; Bandyopadhyay, Debkumar; Singh, D P; Ghosh, Sudipta

doi:10.1179/174328508x283469

Cited by 5 publications

(4 citation statements)

References 3 publications

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“…5. And it can be inferred that for reduction of chromite reaction (3) starts from 1 456 K and reaction (7) starts from 1 301 K (point c), which are much higher than that of iron ore with starting reduction temperature of 992 K for reaction (3) and 1 031 K (point b) for reaction (6). Carbon monoxide reduction of iron in iron ore and chromite is also highly correlated with equilibrium vapor composition.…”

Section: Enhancement Mechanism Of Chromite Reduction In Prereduced Comentioning

confidence: 94%

“…And the prereduced pellets are proved better than traditional "lumpy ore" because they can contribute to lower energy consumption in furnace and better metallurgical properties. [5][6][7] However, chromite ores have extremely high soften-melting temperature, normally more than 1 823 K (increases with the total content of MgO and Al2O3), which may make BF operations difficult. 2,7) Therefore, in order to reduce the melting point of the burden, a mixture of chromite concentrate and iron ore is utilized as feed material to produce prereduced pellets and the coal-based direct reduction process is widely adopted because China is seriously short of natural gas resources but has vast indigenous reserves of reducing coal.…”

Section: Introductionmentioning

confidence: 99%

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Solid State Reduction of Preoxidized Chromite-iron Ore Pellets by Coal

2015

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A comparative study on coal-based solid state reduction of preoxidized chromite pellets and chromiteiron ore pellets was conducted to investigate the reduction behavior of these two types of pellets. And the enhancement mechanism of chromite reduction reactions due to the pre-oxidation process of chromite with magnetite was revealed by means of optical microscopy, SEM with EDS. The results show the presence of iron ore and pre-oxidation process both are advantageous to the reduction of chromite. Preoxidation of chromite and iron ore mixture at 1 323 K for 15 min contributes to more formation of sesquioxide solid solution (Fe, Cr, Al)2O3 than pure chromite oxidation. Massive cations exchange and diffusion occur between chromite and iron ore, which normally cause the decrease of magnesium content and aluminum content and the increase of iron content in spinel solid solution. Accordingly, the chromite reduction is enhanced with the metallization rate of chromite raised from 20.83% in prereduced chromite pellets to 47.98% in prereduced composite pellets at temperature of 1 473 K for 90 min and C/O ratio=1.06, but no further improvement is observed above 1 473 K. The mechanism study based on carbothemic reduction thermodynamics and the microstructure of prereduced pellets reveals the reduction of sesquioxide solid solution (Fe, Cr, Al)2O3 is more thermodynamically supported and the high iron, low magnesium and aluminum spinel solid solution formed in pre-oxidation process is also favorable for chromite reduction because of lower outward diffusion resistance of Fe 2+ to the interface with CO gas.

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Section: Enhancement Mechanism Of Chromite Reduction In Prereduced Comentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Solid State Reduction of Preoxidized Chromite-iron Ore Pellets by Coal

2015

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“…Sinter being porous in nature may have lower thermal conductivity than the lump ore resulting in poor heat transfer from the arc during the initial stage. 17 It has been observed that, for lump ore, a liquid pool was formed beneath the electrodes within 5-7 min of arcing, in comparison to 10-15 min for sinter. This may facilitate early direct heating for lumps by submerged arcing.…”

Section: Comparison Of Chromite Sinter and Lump Ore Smelting Study In...mentioning

confidence: 99%

“…Sintering of chromite ore fines were carried out by Zhu et al 15 and found incipient formation of 20% liquid phase (olivine) in the produced sinter, which shows 70.6% sinter yield and 57.27% tumbler index. Other investigators 16,17 also studied on sintering of chromite ore fines and their performance in smelting in a laboratory scale electric arc furnace (EAF). They showed that the specific power consumption in the melting was comparable with that of the heat hardened chrome ore pellets and lower than the briquettes and lump ores.…”

Section: Introductionmentioning

confidence: 99%

Smelting characteristics of fluxed chromite sinter and its performance assessment in electric arc furnace to produce high carbon ferrochrome

Agarwal

Pal

Ghosh

2016

Ironmaking & Steelmaking

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More than 80% of the high grade chromite ores are fragile and tend to form fines during their handling. In order to utilise these chromite ore fine, in ferrochrome production, agglomeration is necessary. In the present study, the direct sintering of chromite ore fines in the presence of coke breeze has been carried out, which does neither require further grinding of ore fines (210 mm) nor binder. It uses suitable fluxes and coke breeze as heat source to raise temperature up to 16008C and produces a semifused mass (20% molten phases) with good strength. The developed sinter showed very good strength properties suitable for cold handling. Since it contains higher amount of fluxes than conventional pellet, the study on its smelting characteristics is necessary to assess its suitability in Fe-Cr production. In the present paper, smelting reduction characteristics and assessment of its performance with respect to the lump ore in a 50 kVA electric arc furnace have been studied in 10 kg scale. Different smelting parameters such as coke and flux requirement, energy consumption, etc. has been optimised through both thermodynamically and experimentally to get maximum extent of reduction, metallic yield and chromium recovery. Coke (21%), quartzite (7.52%) and bauxite (10%) addition with 45 kWh of heat input was found to be optimum to achieve 76% metallic yield and 91%, chromium recovery. In the comparative study in identical condition, the chromite sinter showed much better metallic yield (76%) and higher chromium content (54.6%) in the produced ferrochrome than the lump ore (70 and 51.9% respectively) of the same grade.

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