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The Kinetics of the Gas-based Reduction of Iron Oxide

Author: ChenGeng
Tutor: ZhangQiuMin
School: Dalian University of Technology
Course: Energy and chemical
Keywords: Iron oxide Sponge iron Iron ore Direct reduction Thermal Analysis Kinetics
CLC: O643.1
Type: Master's thesis
Year: 2011
Downloads: 250
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Abstract


The steel industry is an important basic industry of the national economy in China, direct reduced iron is the most active in the development of China's iron and steel technology, one of the most talked about direction. With the advances in technology of coal chemical industry, coal gas become the dominant method of direct reduced iron production - shaft furnace. In order to restore the reduction of iron ore fines behavior and reaction mechanism of in-depth understanding of gas-based, using thermal gravimetric analyzer, investigated the carbon monoxide concentration of hydrogen concentration of 100%, 75%, 50% and 25%, temperature of 400-750 ° C; was 75%, 50% and 25%, a temperature of 700 to 750 ° C; weight loss behavior of pure methane in a temperature of 800 ~ 950 ℃ and three mixed gas reduction of iron oxide, and analysis of the kinetic parameters under various reaction conditions to determine the iron oxide powder in the reduction process under various conditions and the reaction mechanism. The results show that there are a lot of similarities: the reduction behavior of iron oxide in hydrogen, carbon monoxide, methane, and gas mixture. When the temperature lt; 570 ° C, the order of reduction of iron oxide Fe2O3 → Fe3O4 → Fe; temperature gt; 570 ° C, the order of reduction of iron oxide: Fe2O3 → of Fe3O4 → FeO → Fe. Iron oxide in hydrogen gas concentration of 100%, 75%, 50%, 25%, a reduction reaction, when the temperature is 400-550 ℃, the first stage reduction process (Fe2O3 → Fe3O4) meet the chemical reaction model, the reaction order for 2/3; second stage (Fe3O4 → Fe) reduction process in line with the three-dimensional diffusion model, the reaction order of 1/2. When the temperature is 600 ~ 750 ℃, the first phase (Fe2O3 → Fe3O4) reduction process in line with the chemical reaction model the reaction order of 2/3; reduction process of the second phase (Fe3O4 → FeO) nucleation and subsequent growth model, The reaction order of 3/4; reduction process of the third phase (FeO → Fe) in line with the three-dimensional diffusion model reaction order of 1/2. The iron oxide in the carbon monoxide concentration of 75%, 50%, 25%, reaction temperature is 700 ~ 850 ℃ a reduction reaction. The first stage reduction process (Fe2O3 → Fe3O4) complies with the chemical reaction model, at a concentration of 75%, the reaction order of 2/3, with concentrations less than 50% when the reaction of the three series. The reduction process of the second stage (Fe3O4 → FeO) found that the reaction order of a random nucleation and subsequent growth model, at a concentration of 75%, the reaction order of 2/3, when the concentration is less than 50%. The third stage (FeO → Fe) reduction process in line with the three-dimensional diffusion model, the reaction order of 1/2. Reduction reaction of iron oxide in pure methane gas in the first phase (Fe2O3 → Fe3O4 → FeO) is controlled by the interfacial reaction, the reaction order n = 1/2; late (FeO → Fe) in the second stage of the reaction is controlled by the three-dimensional diffusion . Mixed atmosphere (H2, CO and CH4), the total flow of 40ml/min, in the temperature range of 700 ~ 850 ℃, the iron oxide reduction reaction is divided into three stages. (Fe2O3 → Fe3O4) reduction process of the first stage is the control of chemical reaction, the reaction order of 2/3. Reduction process in line with the second phase (Fe3O4 → FeO) third stage (FeO → Fe) reduction process is a two-dimensional diffusion model, the reaction order of 1/2 to random nucleation and subsequent growth model, the reaction order is 3/4; .

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CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Chemical kinetics
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