Preparation Technologies of Straw Char and Its Effect on Pollutants Emission Reduction in Iron Ore Sintering

et al. 2016

Energy Fuels

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The application characteristics of cost-effective commercial medium-grade charcoal (MG charcoal) in the sinter-making process were assessed in this paper. The results showed that, in comparison to high-grade charcoal (HG charcoal), MG charcoal was characterized by a lower fixed carbon content, a higher volatile content, and a higher porosity and specific surface area, which led to its even greater difference in thermochemical behaviors with coke breeze than HG charcoal. This property of MG charcoal resulted in a faster sintering speed, a lower bed temperature, and a shorter holding time above 1200 °C for adhesive mineral melting, which restrained its proper replacement percentage at 20%, while it was 40% for HG charcoal. To achieve a sintering performance similar to the HG charcoal, the combustion behavior of MG charcoal and coke breeze was regulated simultaneously by coating fine-grained iron ore concentrate and adhering CaO, respectively. It was found that coating concentrate was useful to reduce the combustion rate of MG charcoal for reduced probability to contact air directly, while adhering CaO helped to accelerate the combustion rate of coke breeze as a result of the potential catalytic effect, which finally exhibited a relatively matched combustion speed. Sinter pot trials verified that, after pretreating MG charcoal particles and coke breeze through the pregranulation process, MG charcoal replacing 40% coke breeze showed a comparable sintering performance to the case using 100% coke breeze. The emissions of CO2, SO2, and NO x achieved an obvious reduction by 21.70, 27.75, and 18.31%, respectively.

Section: Results and Discussionmentioning

confidence: 82%

Assessment on the Application of Commercial Medium-Grade Charcoal as a Substitute for Coke Breeze in Iron Ore Sintering

et al. 2016

Energy Fuels

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“…Our 2 Advances in Materials Science and Engineering group also did a lot of work on the influences of biochar replacing coke breeze on sintering process. The research showed that it could reduce emissions of NOx, SOx, and so on when applying the carbonized products of straw, trees, and molded-sawdust [18][19][20][21]. There were lots of differences between biochar and conventional fuels in terms of chemical composition, physical properties, proximate analysis, and so on.…”

Section: Introductionmentioning

confidence: 99%

Gasification Reaction Characteristics between Biochar and CO₂ as well as the Influence on Sintering Process

Advances in Materials Science and Engineering

et al. 2017

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For achieving green production of iron ore sintering, it is significant to substitute biochar, which is a clean and renewable energy, for fossil fuels. In this paper, the gasification reaction between CO 2 and biochar was investigated. The results showed the initial temperature and the final temperature of the gasification reaction between biochar and CO 2 were lower, while the maximum weight loss rate and the biggest heat absorption value were much higher than those of coke breeze, which indicated gasification reaction between the biochar and CO 2 occurred rapidly at lower temperature. The gasification activation energy of biochar was 131.10 kJ/mol, which was lower than that of the coke breeze by 56.26 kJ/mol. Therefore, biochar had a higher reactivity and easily reacted with CO 2 to generate CO. As a result, when biochar replaced coke powder at equal heat condition in sintering process, the combustion efficiency of fuel decreased and was disadvantage to the mineralization of iron ores at high temperature. With the increase of substitute proportion, the sinter yield, tumble strength, and productivity were decreased. The proportion of biochar replacing coke breeze should not be higher than 40%. By reducing the heat replacement ratio of biochar, the yield and quality of sinter got improved.

“…8,9) The raw materials were blended according to their proportions in Table 1, with water added to meet the prescribed moisture content. The mixture was then charged into an electrically powered drum of length 1 400 mm and diameter 600 mm for granulation, which was conducted at 15 rev min − 1 for 4 min.…”

Section: Sinter Pot Testmentioning

confidence: 99%

“…5,7) Unfortunately, no research regarding regulating the characteristics of biomass fuels via developing proper preparation technologies were found with the exception of our previous research. 8,9) According to our research, controlling the carbonization process was able to bridge the differences between biomass fuels and fossil fuel, while only afforded less information about the effect of preformation process, which also played a significant role in biochar preparation. Biomass from plants is a cellular material of high porosity, 10) preformation is able to reduce the volume and improve the energy density of biomass fuel through briquetting the raw biomass into regular particles with the help of mechanical pressure.…”

Section: Introductionmentioning

confidence: 99%

Influence of Preformation Process on Combustibility of Biochar and its Application in Iron Ore Sintering

et al. 2015

ISIJ International

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A study was carried out into the use of preformation process to prepare biochar for replacing coke breeze in iron ore sintering. Two types of preformation process, thermo-compression process (TCP) and normal temperature process (NTP), were adopted. Results show that preformation contributed to improving the density of both raw biomass and biochar. Recommended preformation parameters for TCP were 200°C, 1 min and 120 MPa respectively, while the recommended preformation pressure for NTP was 180 MPa. Compared with non-preformed biochar, the specific surface area and porosity of preformed biochar were considerably reduced. The inner structure of biochar was therefore compacted to close to that of coke breeze. These changes bridged the differences in terms of combustion properties between biochar and coke breeze. Laboratory-scale sintering tests showed that the proper replacement percentage of biochar to coke breeze was increased from 20% to 40% after preformation process, and the emission reduction of SOx and NOx were correspondingly increased from 18.37% and 15.88% to about 38.00% and 27.00% respectively.