Off-gas Dust in an Experimental Blast Furnace

Lowering the carbon consumption and fossil CO 2 emissions is a priority in blast furnace (BF) ironmaking. Renewable biomass is one option that can play an important role in future low-carbon ironmaking particularly in the countries rich in biomass resources. In this study, full-scale trials to investigate the impact of briquettes containing torrefied sawdust on the BF efficiency and process stability have been conducted. Briquettes containing 1.8% of torrefied pelletized sawdust (TPS), 86.2% of steel mill residues, and 12% cement with sufficient mechanical strength have been produced on industrial scale. The bio-briquettes were charged at two different rates: 37% (~ 39 kg/tHM) and 55% (~ 64 kg/tHM) bio-briquettes to the SSAB BF No. 4 in Oxelösund. The gas utilization was higher during bio-briquette-charging periods without change in pressure drop up to 55% bio-briquettes, indicating sustained shaft permeability. BF dust generation or properties did not change significantly. Measurements of the top gas composition using mass spectrometry did not indicate release of hydrocarbon from TPS in connection to the charging of bio-briquettes. Evaluation of process data has been carried out using a heat and mass balance model. The evaluation of operational data in the model indicated lowering of thermal reserve zone temperature by 45 °C and reduction in carbon consumption by ~ 10 kg/tHM when charging 55% bio-briquettes compared to the reference case. The total CO 2 emission was reduced by about 33-40 kg/tHM when using 55% bio-briquettes. Keywords Ironmaking • Blast furnace • Bio-briquettes • CO 2 emission • Torrefied sawdust Abbreviations B2 CaO SiO 2 BF Blast furnace EBF Experimental blast furnace Fe met Metallic iron Fe tot Total iron EtaCO Carbon monoxide efficiency, EtaCO = %CO 2 %CO+%CO 2 EtaH 2 Hydrogen efficiency, EtaH 2 = %H 2 O %H 2 +%H 2 O HM Hot metal The contributing editor for this article was I. Sohn.

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“…3. Detected phases are hematite, calcium carbonate, quartz, and magnetite, and the results are in line with previous studies [34].…”

Section: Top Gas Sampling and Analysessupporting

confidence: 92%

Reduced Carbon Consumption and CO2 Emission at the Blast Furnace by Use of Briquettes Containing Torrefied Sawdust

Mousa

Lundgren

Ökvist

et al. 2019

J. Sustain. Metall.

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“…Yang et al [11] changed the composition of slag in an experiment and fitted the relationship between the capacity change in alkali metals corresponding to the slag. On the other hand, the amount of alkali metals discharged in the top gas is related to the type of blast furnace gas flow and burden distribution [12]. During blast furnace operation, the coke ratio and gas utilization ratio in the blast furnace have the most direct influence on the profits.…”

Section: Introductionmentioning

confidence: 99%

Influence of multiple factors on the alkali metal enrichment in blast furnaces by a thermodynamic model

Chen

Wang

et al. 2020

Ironmaking & Steelmaking

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Alkali metal circulation enrichment occurs in blast furnaces, which is harmful to the blast furnace. The amount of enrichment helps to quantify the effect of alkali metals on blast furnace production, but it is not possible to directly measure the actual alkali metal enrichment in blast furnaces for technical reasons. On the basis of a thermodynamic model, FactSage was used to calculate the effects of alkali loading, slag basicity, MgO content in the slag and Al 2 O 3 content in the slag on the alkali metal enrichment in the blast furnace. Quantitative relationships among various factors and the enrichment were obtained, and the degree of influence of various factors on the amount of enrichment was determined. The basicity B 2 of the slag was the key factor for enrichment. With an increase in the slag basicity of 0.1, the enrichment of K and Na increased by 5.3 and 1.6 kg/tHM, respectively.

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“…During the feeding processes, such as handling, transportation and charging, pellets typically undergo a mechanical wear which is reported as being one important source for the dust formation. 1,2) However, it is unclear to what the exact contribution of the dust generation from a wear contact between pellets is in a real industrial blast furnace. In order to simplify the complexity inherent in a field test, a redesigned tribometer combined with a ventilation chamber was developed to determine the correlation between the wear contact of pellets and the particle generation.…”

Section: Introductionmentioning

confidence: 99%

A Simulation Study of Particles Generated from Pellet Wear Contacts during a Laboratory Test

et al. 2016

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In the blast furnace process, material losses occur due to mechanical wear between charged iron ore pellets and are exhausted in the form of dust in the off-gases. A redesigned tribometer combined with a ventilation chamber was developed to identify the dust emission from the mechanical wear contact of pellets. In order to obtain a better understanding of the measurement results, a coupled drift flux with a unified Eulerian deposition model was adopted to investigate particle dispersion and deposition during tests. Two influential factors, namely the air condition (5-20 L/min) and particle size (1-20 μm) were examined. The predicted results were presented by introducing two parameters, namely the measurable fraction and the deposition fraction. For each air condition, the measurable fraction declines while the deposition fraction rises as particle size grows. The critical size of the particles that becomes airborne and captured at the outlet was identified to be around 20 μm. In addition, a high airflow rate supplied at the inlet was observed to be favorable for improving the measurable fraction. Nevertheless, the results show that nearly 50% of emitted particles (1-20 μm) that failed to be captured during tests. Thus it could be expected that these generated particles would be transported deeply in a blast furnace if they are not efficiently removed from the off-gas. As a consequence, they may influence the quality of the products. Furthermore, the validation of the simulation results against the experimental data was achieved by using the predicted measurable fraction.

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Off-gas Dust in an Experimental Blast Furnace

Cited by 13 publications

References 9 publications

Reduced Carbon Consumption and CO2 Emission at the Blast Furnace by Use of Briquettes Containing Torrefied Sawdust

Reduced Carbon Consumption and CO2 Emission at the Blast Furnace by Use of Briquettes Containing Torrefied Sawdust

Influence of multiple factors on the alkali metal enrichment in blast furnaces by a thermodynamic model

A Simulation Study of Particles Generated from Pellet Wear Contacts during a Laboratory Test

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