| 1. |
- Bustnes, J. A., et al.
(författare)
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Investigation of the reduction of ZnWO4 by hydrogen gas
- 2000
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Ingår i: Zeitschrift für Metallkunde. - 0044-3093. ; 91:6, s. 500-503
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Tidskriftsartikel (refereegranskat)abstract
- The reduction of zinc tungstate by hydrogen gas was studied using a thermogravimetric method in the temperature range 823 to 1073 K. The experiments were carried out isothermally. A new W to Zn binary phase was found in the samples reduced at 873 K. This discovery is in disagreement with the earlier information on Zn-W phase equilibria that Zn and W do not form alloys. The favorable kinetic conditions would be of help for the formation of this phase. On the other hand, this phase was not observed in the sample reduced at 1073 K. The evaporation of zinc during the reduction was found to play an important role. The apparent activation energy for the reduction of ZnWO4 by hydrogen was evaluated to be 90 kJ/mole using the initial reaction rates.
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| 2. |
- Jakobsson, A., et al.
(författare)
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Interfacial phenomena in some slag-metal reactions
- 2000
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Ingår i: Metallurgical and materials transactions. B, process metallurgy and materials processing science. - : Springer Science and Business Media LLC. - 1073-5615 .- 1543-1916. ; 31:5, s. 973-980
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, the change of the interfacial tension at the slag-metal interface for sulfur transfer between molten iron, slag, and gas phases was monitored by X-ray sessile drop method in dynamic mode in the temperature range of 1830 to 1891 K. The experiments were carried out with pure iron samples immersed partly or fully in the slag phase. The slag consisted of 30 wt pet CaO, 50 wt pet Al2O3, and 20 wt pet SiO2 (alumina saturated at the experimental temperatures) with additions of FeO. Metal and slag samples contained in alumina crucibles were exposed to a CO-CO2-SO2-Ar gas mixture with defined oxygen and sulfur partial pressures, and the change of the shape of the metal drop was determined as a function of time. The equipment and the technique were calibrated by measurements of the surface tensions of the pure Cu, Ni, and Fe containing two different amounts of dissolved oxygen. A theoretical model was developed to determine the sulfur content of the metal as a function of time on the basis of sulfur diffusion in the slag and metal phases as well as surface tension-induced flow on the metal drop surface. Attempts were made to compute the interfacial tensions on the basis of force balance.
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| 3. |
- Sahajwalla, V., et al.
(författare)
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Structure and alkali content of coke in an experimental blast furnace and their gasification reaction
- 2004
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Ingår i: Iron & Steel Technology Conference proceedings. - Warrendale, Pa : Iron and Steel Society. - 1886362750 ; , s. 491-500
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Konferensbidrag (refereegranskat)abstract
- Coke samples excavated from LKAB's Experimental Blast Furnace (EBF) at MEFOS in Luleå, Sweden were used to observe the influence of in-furnace reactions on the changes in chemical stracture of cokes and their influence on kinetics of CO 2 reactivity. In addition to growth of carbon crystallite of coke, alkali concentration particularly potassium and sodium were found to increase as coke descended towards lower part of the EBF. The increase in carbon structure could be linearly related to measured temperature profiles of EBF. Isothermal and non-isothermal TGA measurements are shown to indicate that CO 2 reactivity of coke becomes progressively faster as it moves towards lower part of blast furnace. The study suggests that alkali enrichment of cokes in an operating blast furnace could have a strong catalytic effect on the CO 2 reactivity. Further research is expected to clarify the mechanisms of influence of coke minerals on reactivity and their implications in a blast furnace.
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