| 2. |
- Kumar, TK Sandeep, 1986-, et al.
(författare)
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Developing the Oxidation Kinetic Model for Magnetite Pellet
- 2019
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Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer. - 1073-5615 .- 1543-1916. ; 50:1, s. 162-172
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Tidskriftsartikel (refereegranskat)abstract
- Oxidation is a vital phenomenon for magnetite pellets in their excursion through the furnace during induration. One of the pre-requisites for magnetite pellets to achieve homogeneously structured good quality pellets is to have complete oxidation before sintering begins. Partially oxidized magnetite pellets, upon sintering, might result in inhomogeneous structured pellets which could be detrimental to pellet quality. It is necessary to understand the mechanisms responsible for magnetite oxidation, and hence, it is intended in this study to investigate experimentally as well as develop a mathematical model based on oxidation kinetics. Oxidation of pellets is largely influenced by the oxidation kinetics of particles and hence should be studied at particle as well as at pellet scale. The principles of the Grain Model have been adopted to develop the Oxidation Model at pellet scale, whereas the particles’ oxidation follows the Avrami Kinetic Model. Isothermal oxidation experiments performed Thermogravimetric Analyzer showed that oxidation rate of magnetite at pellet scale contained two peaks. They were complemented well by oxidation rates predicted from the model. Further, the pellet was investigated microstructurally at pellet and particle scale to substantiate the findings from the experiments and the model. The oxidation model developed is used to predict the progression of oxidation in the magnetite pellet with respect to the reaction time at three different temperatures (873 K, 973 K, and 1073 K (600 °C, 700 °C, and 800 °C)) and at four levels of oxygen (0.21, 0.30, 0.60, and 1.00 atm) in the oxidizing gas.
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| 4. |
- Nurni, Viswanathan, et al.
(författare)
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A methodology to quantify the physico-chemical phenomena during induration of a single magnetite pellet
- 2017
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Konferensbidrag (refereegranskat)abstract
- Induration of magnetite pellet involves three important phenomena, namely oxidation, sintering and associate heat transfer; these phenomena are interdependent on determining the final quality of the pellet. In order to study the sintering a novel optical dilatometric method was used. These studies were performed separately for magnetite and completely oxidized magnetite. Further, the sintering phenomena was modeled taking cues from powder metallurgy literature. In order to study the oxidation kinetics, TGA analysis were conducted both at powder and pellet scales at sufficiently low enough temperatures so that sintering effects are minimized. Interesting results that has not been reported earlier have been observed and these results could be explained using available gas-solid reactions models both at powder and pellet scales. Once the sintering and oxidation models were validated independently, they were integrated along with heat transfer model to realize a comprehensive induration model. These efforts have resulted in a Single Magnetite Pellet Induration Model (SPIM) which in principle can be used for optimizing raw material mix as well as the process parameters at the reactor scale.
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