Surface tension driven flow during oxygen top blowing of liquid copper

Marin, T.1, 2, Utigard, T.1
1 Univeristy of Toronto, Materials Science and Engineering
2 Universidad de Chile, Departamento de Ingenieria de Minas

The rate of liquid copper oxidation plays an important role in the separation of impurities from copper during fire refining.

A finite elements numerical model using FEMLAB 3.1 for the oxidation of liquid copper during top blowing of oxygen/nitrogen mixtures is presented and compared to experimental results. In this model, surface tension driven flow arising from gradients of oxygen concentration in the surface of liquid copper is incorporated using the weak boundary model and is coupled to incompressible fluid flow and convection plus diffusion of oxygen within the liquid.

A transient analysis shows that the rate of liquid copper oxidation is dramatically enhanced when Marangoni effect is incorporated to the model, which explains the experimentally observed rates of oxidation that cannot be explained by diffusion only. Buoyancy forces due to a decrease in density of the oxygen rich melt are also included in the study; this force affects the overall velocity profile, and therefore the oxygen distribution inside the melt.

The model agrees well with experimental results that show oxygen segregation along the height of the liquid copper.