Mathematical modeling of the natural solar drying process in lateritic mineral deposits

Abstract

The natural solar drying of lateritic mineral was modeled in order to obtain the moisture distribution and its movement mechanism in the section. In this work we give a physical model of the drying process, based on heat and moisture transport phenomena in porous media. The models that allow calculation of the heat fluxes by radiation, convection and conduction are determined; In addition the global solar radiation that affects the surface of minerals drying; the temperature and humidity distribution experienced by the material during the process; the rate of drying and the mineral moisture on the surface. Natural drying tests were performed and experimental values of material moisture were obtained. The experimental and theoretical results obtained were compared. The validation process was performed by comparing the moisture of the experimentally determined material with the theoretical humidity calculated with the models for the same physical conditions in which the experiment was developed. The mathematical models were obtained by solving, through the variable separation method, the differential equation of moisture exchange in a porous solid for the initial and boundary conditions specific to the natural drying. The results evidenced that during the process, significant changes in the moisture of the material occur until the layers that are separated about 29 and 87 cm from the surface of the east and west slopes of the pile respectively. In addition, it was confirmed that the moisture movement in the ore piles occurs through a mixed transport mechanism; combined effects of vapor diffusion, liquid diffusion and liquid movement.