Control of Reverse Emulsification and Mixing Time in a Bottom Blown Bath Covered with Top Slag

Due to the high-quality steel demand, especially for ultra-low Sulfur steel, RH desulfurization has been practiced. Based on this, mathematical and physical modeling have been applied to study steel desulfurization by reagent addition in the RH degasser vacuum chamber. The main result of cold modeling, using water and oil emulating steel and slag, respectively, was to assess the influence of density difference between the continuous and disperse phases on oil droplet behavior. It is shown that its flow tends to be more restricted near the down snorkel when the density difference increases. Moreover, these results provide the basis for CFD modeling validation, which enabled the determination of slag drop residence time inside steel on RH and the average value of the rate of dissipation of turbulent kinetic energy inside the RH ladle. These two parameters were used to develop a kinetic model, which reaches a good agreement with industrial trial results available in literature. The optimum desulfurization degree of 31.44% was achieved for a gas flow rate of 90 Nm 3 /h, according to the kinetic model. This value can be useful in some steel grade production, where the required S content is less than 10 ppm. Even in common steel grade production, if some punctual chemical adjustment is necessary, this technique is also useful. The main kinetic parameter for steel desulfurization is the steel circulation rate. For best results, it should be reduced in the desulfurization stage, and after that, the normal operation can be resumed, so that the production cycle is not affected.

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“…(a) 1cSt = 1centistokes = 0.01cm²/s = 0.000001m²/s; (b) Yamashita and Iguchi (2003); (c) measured values.…”

Section: Thymol Mass Transfer In An Oil-aqueous Solution Systemmentioning

confidence: 99%

Steel desulfurization on RH degasser: physical and mathematical modeling

et al. 2022

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“…1 Therefore, developing a technology for introducing alloy addition to steel also during the course of continuous casting is one approach for enhancing the steelmaking process, especially as the effective introduction of micro-additives or non-metallic inclusion modifiers to the liquid steel is the key to the production of the highest quality steel. [2][3][4] During secondary metallurgy treatment, introduced alloy additions mix with the steel due to metal circulation induced by stirring the metal bath with inert gas. Therefore, during the injection of inert gases care must be taken to correctly select the intensity of gas flow so as to minimise the phenomenon of the slag phase being washed away over the gas permeable block and the slag phase emulsifying with the liquid steel.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulations and industrial experiments of liquid steel alloying process in one strand slab tundish

Cwudziński

2014

Ironmaking & Steelmaking

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The present paper discusses the results of tests in which batches of nickel in the form of crowns were introduced to liquid steel in a continuous casting slab tundish during experiments to investigate steel alloying during casting. Suction liquid steel samples taken from both tundish and mould were assayed for chemical composition. Computer simulations of liquid steel flow and alloy addition behaviour were performed using the commercial program Ansys-Fluent. Owing to the complexity of alloy dissolution and dispersion in metallurgical processes, a decision was made to use the Species Model. The obtained fields of liquid steel flow and nickel distribution and the curves of nickel concentration in time constitute a source of information about the dynamics and complexity of the steel alloying process during continuous steel casting. The present studies show influence of different addition positions and different flow control devices on liquid steel chemical homogenisation process.

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“…They also proposed an empirical equation for calculation of mixing time. Yamashita and Iguchi 5,6 reported that mixing time increases due to the presence of an upper buoyant phase because recirculating flows are suppressed and reverse emulsification takes place. The entrapment of many oil droplets in the water layer weakened the large scale recirculating flow in the bath, and hence prolonged the mixing time.…”

Section: Introductionmentioning

confidence: 99%

Optimisation of dual purging location for better mixing in ladle: a water model study

Chattopadhyay

Sengupta

Ajmani

et al. 2009

Ironmaking & Steelmaking

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Mixing time studies were performed on a one-fifth scale aqueous model of a single tapered ladle with different bottom purging locations. Two porous plugs were used simultaneously to purge compressed air as an analogue to argon and this was referred as dual purging. KCl solution (1 N) was used as the tracer for measuring mixing time. The scaled down gas flowrate varied from 10 to 80 L m 21 . Around 400 experiments were done including all possible dual purging locations and the location which gives least mixing time was identified. The results were compared with corresponding single purging experiments and it was found that dual purging can reduce mixing time to a great extent even in the lower flowrate range and a location better than ¡R/2 has been suggested. Effect of differential flow on mixing time has also been reported.

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Control of Reverse Emulsification and Mixing Time in a Bottom Blown Bath Covered with Top Slag

Cited by 10 publications

References 6 publications

Steel desulfurization on RH degasser: physical and mathematical modeling

Steel desulfurization on RH degasser: physical and mathematical modeling

Numerical simulations and industrial experiments of liquid steel alloying process in one strand slab tundish

Optimisation of dual purging location for better mixing in ladle: a water model study

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