Experimental investigation and modeling of conductive drying of washing phosphate sludge with and without shrinking effect

The purpose of this work is to investigate experimentally the effect of drying temperature and thickness on the drying curve of a conductive drying of washing phosphate sludge samples. Two mathematical models based on Fourier's Fick diffusion law and heat transfer equation were developed to simulate the drying. The first model neglected the shrinking effect while the second one took it into account. The findings showed that drying temperature increase and/or the samples thickness decrease enhance the drying rate. Furthermore, the drying curves showed the presence of the three classical drying periods corresponding to: adaptation, constant drying rate and falling drying rate periods. Based on the analytical solutions and according to the statistical criteria (R 2 , RMSE), it was concluded that the model incorporating the shrinking effect is the best model to describe the drying behavior of washing phosphate sludge in all tested conductive drying conditions.