Improvement of Reactivity of Carbon Iron Ore Composite with Biomass Char for Blast Furnace

Abstract

Enhancement of reactivity of the burden in the blast furnace can decrease the reducing agent of blast furnace. Besides high reactivity coke, the carbon iron ore composite is considered to be a typical high reactivity burden that can control the thermal reserve zone temperature. Since the reactivity of biomass char is much higher than that of coke, the use of carbon iron ore composite with biomass char will be favorable for decreasing the reducing agent. In the present study the reaction and reducing behavior of the carbon iron ore composite with biomass char were investigated. The gasification rate of biomass char was measured in CO 2 atmosphere, and the reaction rate equation of that was derived. The microscopic structure change of biomass during carbonization was experimentally analyzed. According to the experimental results, the reduction of the composite begins at about 550°C in an inert gas atmosphere, and it is much lower than the composite with coke. Analysis of the reaction of carbon iron ore composite was carried out with the reaction model of the carbon iron ore composite based on a lumped system, in which the reaction rate of biomass char and iron ore were installed. The reaction model shows that the biomass char can improve the reduction behavior of the carbon iron ore composite especially in the lower temperature region. Moreover, the influence of gas atmosphere and the optimum structure of the composite were investigated by the model calculation to estimate the optimum condition of the composite in the blast furnace.KEY WORDS: biomass char; carbon iron ore composite; mathematical model; carbon gasification; blast furnace; carbon dioxide; ironmaking. 1505© 2009 ISIJ used as reducing agent in the composite. Decomposition temperature ranges of cellulose and hemicellulose are from 250 to 400°C and from 180 to 300°C, respectively. 13) If biomass is carbonized in over the temperature ranges, the structure of cellulose would be decomposed and the grind ability of that would be improved. In the present study, carbonization of biomass over 400°C in an inert gas was employed as the pretreatment method of biomass char. Carbonization of BiomassCarbonization of biomass was carried out over 400°C at an inert gas, namely Ar atmosphere. Lumber of Japanese cedar was used as a biomass. That was cut into a piece of 10 mmϫ10 mmϫ50 mm. In order to consider of heat pattern for carbonization, two initial conditions for heating were employed, (1) Hot start condition; the biomass was charged into heated furnace at the specified temperature, and (2) Cold start condition; after charging the biomass into the furnace, the sample heated with increasing temperature at a rate of 0.167°C/s. For both condition, after reaching the specified temperature, the biomass was kept in the furnace for 7 200 s.The composition of raw biomass used in the present experiment and biomass chars carbonized in various temperatures were listed in Table 1. Concentration of C, H and N in organic substance, and ash were analyzed and concentration of O wa...

Reduction Mechanism of Composite Consisted of Coal and Hematite Ore by Volatile Matter at 700–1100 K

“…Furthermore, it was observed herein that the cracking reaction was initiated at lower temperature than previously reported. 13) It is probable that decomposition of CH 4 gas is promoted by the iron oxide catalyst. 26) The generation of H 2 O gas can also be observed.…”

“…Thus, development of methods for utilizing low-grade resources is another active area of study. Several studies for utilization of coal with high volatile matter content, 10) semicoal-chars, 11) waste plastic, 12) and biomass, 13) have been reported. These carbonaceous materials have the common characteristic of containing volatile matter.…”

Reduction Mechanism of Iron Oxide–Carbon Composite with Polyethylene at Lower Temperature

“…Many carbonaceous materials, such as coal, coke, biomass, and so on have been examined as possible reductants for the composites. [3][4][5][6][7] The focus has been on carbonaceous materials which can accelerate the reduction at lower temperature.…”

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

“…With carbonisation temperature increasing, where heating rate and carbonisation time were kept at 25°C/min and 30 min, yield and volatile matters tended to decrease, the results were similar to that described by Shigeru. 17) Possible reason was the deep removal of O and H in raw straw at higher temperature for greater carbonisation intensity. Increased fixed carbon content was then the result that more carbon was entered into solid products at higher carbonisation temperature.…”

“…Potential reason for superiority of two-stage carbonisation was as follows: cellulose and lignin in raw straw decomposed with competing reactions of de-H2O, de-CO2, 17) the comprehensive effect of which determined the yield, fixed carbon and volatile contents of straw char. Table 6 gives the ultimate analyses of C, H, and O in straw char, according to which the removal percents of C, H, and O were figured out by Eq.…”