Effects of high gravity on dissolution of solid modifiers in molten slag

Abstract

High-gravity technology was applied to the dissolution process between molten slag and solid modifiers to accelerate the modification of hot slag. In this study, MgO and SiO2 rods were chosen as typical modifiers, and the effects of high-gravity (G = 800) and normal-gravity (G = 1) fields on the dissolution process between molten slag and solid modifiers were researched. The effects of high-gravity forces on the penetration depth and boundary layer of the dissolution process of the rod in molten slag were investigated using optical micrographs, X-ray fluorescence, X-ray diffraction, scanning electron microscopy, and electron probe microanalysis. Under high gravity conditions, the penetration depth of the slag melt into the solid rod was larger because the melt could enter deeper and smaller cracks and gaps, which increased the contact area and accelerated the dissolution process. The penetration depth increased from 0.1 mm to 1.07 mm in the MgO rod system and from 0.55 mm to 1.99 mm in the SiO2 rod system. Moreover, the boundary layer of ions between the solid rod and slag melt became thinner, which promoted the diffusion of ions; the boundary layer thicknesses were reduced from 1.91 μm to 0.45 μm in the MgO rod system and from 96.88 μm to 51.63 μm in the SiO2 rod system. In addition, high centrifugal forces could remove pores by pushing air bubbles from inner liquid–solid interfaces to the surface of the molten slag. The elimination of bubbles at the interfaces favored the penetration and dissolution processes. This study provides a rapid and effective new modification method to reduce the energy loss of molten slag and increase the output of modified slag.