A numerical investigation on the conductive drying process for phosphate sludge

Phosphate production generates huge quantities of waste materials that pose both economic and environmental challenges. They are characterized by a high-water content, making disposal a very difficult task. To address this issue, conductive drying emerges as a viable solution to reduce the water content in the phosphate sludge to facilitate handling and specially recycling them as construction materials. This paper presents a simplified numerical model based on Fick's law, depicting heat and mass transfer in porous media to simulate the conductive drying process within the phosphate sludge. To provide more accuracy to the numerical model solution, the experimental data are integrated into the numerical model as boundary conditions, enabling the prediction of temperature profiles, thermal conductivity, and effective moisture diffusivity throughout the conductive drying process. The water evaporation capacity is found between 1.25 and 2.1 kg water/m2.h.These findings could be a tool for designing a suitable dryer for phosphate washing sludge.