| 1. |
- Kapilashrami, A., et al.
(författare)
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Bubble formation through reaction at liquid-liquid interfaces
- 2005
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Ingår i: Steel Research International. - : Wiley. - 1611-3683. ; 76:9, s. 616-623
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Tidskriftsartikel (refereegranskat)abstract
- Slag foaming is an important phenomenon in steelmaking processes with both beneficial as well as negative effects. The present work is part of the wider project on the modelling of slag foaming, with special reference to dynamic conditions. Since bubble formation is the first step to foam formation, the present work was carried out in an attempt to simulate the bubble formation in slag/metal reactions in steelmaking processes by water-modelling experiments. The bubble formation due to the gas produced through chemical reaction at the interface between oleic acid and sodium bicarbonate solution was systematically monitored. The chemical reaction rate was varied by varying the concentration of sodium bicarbonate. The bubbles were observed to be generated in the heavier aqueous phase just below the water-oil interface. The bubbles penetrated the interface and escaped through the oil phase. The rate of the reaction was estimated from the volume of the gas that passed the water/oil interface. It was observed that the bubble formation and bubble growth mechanism were influenced by the reaction rate while the bubble size seemed to be unaffected by the reaction rate.
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| 2. |
- Kapilashrami, A., et al.
(författare)
-
Foaming of slags under dynamic conditions
- 2006
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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. ; 37:1, s. 109-117
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Tidskriftsartikel (refereegranskat)abstract
- Slag foaming under dynamic conditions has been studied in laboratory scale to examine the influence of properties commonly used to describe the foaminess and foam stability of slags under steady-state conditions. Synthetically produced slags with compositions relevant to tool steel and stainless steel production were studied through X-ray equipment in measurements simulating the dynamic conditions found in real processes. It is found that the dynamic systems display a more complex behavior than systems Under steady state. Traditional theories for foaming do not seem to be valid for slag foaming under dynamic conditions. The foam displays a fluctuating behavior, which the presently available models are not able to take into account. The concept of a foaming index does not seem to be applicable, resulting in the need for alternative models.
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| 3. |
- Kapilashrami, A., et al.
(författare)
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The fluctuations in slag foam under dynamic conditions
- 2006
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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. ; 37:1, s. 145-148
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Tidskriftsartikel (refereegranskat)abstract
- ABHA KAPILASHRAMI, formerly with the Royal Institute of Technology, is with Corus Research, Development and Technology, 1970 CA IJmuiden, The Netherlands. ASHOK KUMAR LAHIRI, Professor, is with the Department of Metallurgy, Indian Institute of Science, Bangalore 560012, India. MARTEN GORNERUP and SESHADRI SEETHARAMAN, Professor, are with the Department of Material Science and Engineering, Royal Institute of Technology, 10044 Stockholm, Sweden. Contact c-mail: raman@ kth.se.
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| 4. |
- Kapilashrami, Abha, et al.
(författare)
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Bubble formation and dynamic slag foaming phenomena
- 2006
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Ingår i: 2006 TMS Fall Extraction and Processing Division: Sohn International Symposium. - 0873396332 - 9780873396332 ; , s. 233-245
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Konferensbidrag (refereegranskat)abstract
- Slag foaming proves to be both blessing and curse for the process productivity, depending on where in the process it occurs. In pyrometallurgical processes, slag foaming is often a result of chemical reactions taking place in the slag. As the slag composition and reaction rates are changing, foaming occurs under dynamic conditions. In the present work, slag foaming was studied with XRF. The foam displayed a fluctuating behaviour, unaccountable by existing models. The concept of foaming index was found not to be satisfactory in describing the foam, resulting in the need for alternative theories. The rate of fluctuations was seen to be related to the difference between rate of gas generation and rate of gas escape from the system (Ug-Ue) as well as the bubble sizes. Thus, model development of dynamic foaming phenomenon has to take the effective chemical reaction rate as well as the bubble sizes into consideration. The first step in obtaining foam is to form bubbles. In the present work, gas bubbles were generated through chemical reaction at interface between two immiscible liquids and the bubble formation was studied optically. The gas bubble size was seen to be uninfluenced by the reaction rate. However, bubble formation was seen to take place in one of the phases and since the bubbles consequently traversed the interface under the influence of buoyancy, the viscosity of the first phase was found to influence the final bubble size where increased viscosity would yield a larger bubble size.
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