Sedimentação de suspensões aquosas de carbonato de cálcio em condições não isotérmicas: uma investigação experimental por atenuação de raios Gama

Abstract

This study investigated the sedimentation behavior of solid particles under lateral heating conditions, with emphasis on the coupling between particulate mass transport and heat transfer mechanisms. The experimental system consisted of an aqueous calcium carbonate suspension, and dyed silica oxide was employed as a tracer previously validated in terms of density and particle size distribution compatibility. Physical characterization was performed through pycnometry and laser diffraction analysis. The final structure of the sedimented bed was determined using the gamma-ray attenuation technique, enabling the determination of vertical profiles of local solid volume fraction. Thermal measurements revealed the development of a significant lateral temperature gradient near the oil reservoirs, establishing a non-isothermal condition along the width of the experimental cell. The solid volume fraction profiles indicated a consolidated bed with values ranging from approximately 0.52 to 0.55 in the lower region, accompanied by a systematic lateral displacement of the solid–liquid interface near the walls. The hypothesis of differential compaction was ruled out, as no significant variations in packing degree were observed across the cell width. Visual analysis using the tracer revealed inclined sedimented structures near the walls, consistent with transverse particle redistribution induced by natural convection arising from the imposed thermal gradient. The results demonstrate that sedimentation under lateral heating exhibits multi-dimensional behavior governed by the coupling between mass transport and heat transfer, and therefore cannot be adequately described by a simplified one-dimensional isothermal model.