Dryers play a central role in the processing of phosphate rock, where moisture removal is essential for downstream handling and energy efficiency. Due to the inherently nonlinear and multivariable nature of these systems, accurate modeling and control remain industrial challenges. This article presents a comprehensive nonlinear dynamic model of a phosphate-pebble rotary drying process, built from first principles to capture coupled heat and mass transfer, evaporation kinetics, and subsystem inte...