Abstract
The presented paper deals with the use of physical modelling to study the degassing process of aluminium melts in the refining ladle by blowing inert gas through a rotating impeller. For the purposes of physical modelling, a plexiglass model in a scale of 1:1 is used for the operating ladle. Part of the physical model is a hollow shaft used for gas supply that is equipped with an impeller and two baffles. The degassing process of aluminium melt by blowing of inert gas is simulated at physical modelling by a decrease of dissolved oxygen in the model liquid (water). This paper is aimed at the evaluation of laboratory experiments that were obtained by the method of physical modelling. Attention is focused on the assessment of relevant parameters for the degassing process—rotary impeller speeds, volume flow rate of inert gas, the distance of the impeller from the bottom of the refining ladle, and impeller variant. The preliminary results of physical modelling show that the optimal results of the refining process are achieved by using the F2A 190 impeller.
Highlights
Emphasis has increasingly been placed on the melt refining processes for removing gases [1,2,3,4], metallic impurities, and non-metallic impurities during processing due to the increasing demand of aluminium casting quality
The main optimization parameters are the rotary impeller speed and the amount of blown inert gas [8,9,10]. The efficiency of this rotary refining depends on the creation of fine bubbles with a high interphase surface, wide-spread distribution, residence time of its effect in the melt, and mostly on the widespread dispersion of bubbles into the whole volume of the refining ladle. This is most affected by the rotary impeller speeds and the amount of blown inert gas
Results were compared by the use of combined graphs, in the second phase, the results were compared on the basis of the requirements for reaching a dimensionless concentration in the bath and, in the last evaluation phase, visualization photos were taken, where the size of bubbles and the distribution of these bubbles into the volume of the refining ladle were studied
Summary
Emphasis has increasingly been placed on the melt refining processes for removing gases (hydrogen) [1,2,3,4], metallic impurities (sodium, calcium, lithium, etc.), and non-metallic impurities (oxides, nitrides, borides, carbides, etc.) during processing due to the increasing demand of aluminium casting quality. The Influence of Rotary Impeller Speeds and Flow Rate of Inert Gas for the Individual Impellers
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