Physical modelling is successfully used to understand mechanisms involved in the aluminium refining process by injecting inert gas into the liquid metal through rotors. Two types of industrial impellers, which are extremely different in construction, were tested in the research. The aim of the research was to determine the effectiveness of their operation depending on their degree of wear. This type of research has not been tested on water models so far. During the process, the parameters were changed, such as the gas flow rate from 13 to 19 L/min, the rotor speed from 325 to 400 rpm and the height of the rotor from the bottom of the refining reactor. Tests were carried out for new and worn rotors. Oxygen removal rate curves were prepared on the basis of tests determining changes in oxygen content in the model liquid as a function of time for changing rotor speed values. It was found that the efficiency of hydrogen removal from the model liquid was higher when worn impellers were used in the model. In order to verify results of model tests, a metallographic analysis of samples obtained in industrial conditions and using the analysed process parameters was carried out.

Environmental Research Department Institute of Technology and Business in České Budějovice Okružní 517 10 370 04 České Budějovice Czech Republic

Faculty of Materials Engineering Silesian University of Technology Krasinskiego 8 40 019 Katowice Poland

MOTOR JIKOV Slévárna a s Die casting Division Kněžskodvorská 2277 370 04 České Budějovice Czech Republic

University of West Bohemia Univerzitní 2732 301 00 Plzeň Czech Republic

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