The objective of this study was to evaluate the effect of the variables of the coating process of stone-breaker (Phyllanthus niruri L.) granules with polymeric suspension in a conventional spouted bed dryer whilst on the evaporation rate. The granules were obtained from the granulation process by wet dry extract of breaking stone, using PVP-K30 as a binder. The suspension of the base polymer Eudragit® was atomized on the bed of particles through the atomized dual-fluid, located at the top of the column. A central rotatable composite design (CRCD) symmetrical and of second order was realized, constituted of a factorial 23, with 8 tests, 3 central points, and 6 axial points, totalizing 17 experiments. The results showed that the evaporation rate correlated positively with the suspension flow rate, while pressure and temperature had no significant effect on the evaporation rate. The experimental design enabled the development of statistically significant predictive models for the evaporation rate. Regarding the effect of the interactions between process variables on the evaporation rate, flow/temperature, pressure/flow and pressure/temperature significantly affected the evaporation rate.
spouted bed; drying; polymeric suspension
