Visualization of CO Bubbles Evolution Accompanying the Silica Reduction Reaction by X-ray Fluoroscopy

Abstract

The X-ray fluoroscopy technique has been successfully applied in studying the CO bubble evolution accompanied with the reduction of silica in blast furnace type slag by carbon-saturated iron in graphite crucible. Visual images have been obtained of the residence and behaviour of the bubbles at slag/metal and slag/graphite interface.
The main results obtained are as follows:
(1) The rate of bubble evolution at each interface varies with temperature and slag composition.
(2) The bubble evolution at slag/graphite interface proceeds more slowly than that at slag/metal interface and is accelerated when slag wets the interface. The shapes of detaching bubbles from the interface are spherical and their diameters are not more than 3 mm.
(3) The aspect of bubble evolution at slag/metal interface differs greatly with a period of the reaction. In the initial stage, numerous small bubbles evolve vigorously all over the interface, while in the later stage, large bubbles of dome shape are formed periodically at certain sites of the interface.
(4) The volume of detaching bubble from the interface in stationary state is nearly equal to that calculated from the balance between buoyancy and interfacial tension force.