EXPERIMENTAL STUDIES OF SEED PELLETIZING IN A DRUM PELLTIZER

Abstract

Due to insufficiently studied conditions of pelletizing seeds with diatomaceous-sand and clay-sand mixtures (DSM and CSM), the author conducted experimental research of pelletizing modes of DSM and CSM seeds in a pelletizer made of glass and having the form of an elliptical rotation paraboloid with a base diameter of 60 mm. The author formulated requirements for the quality of pellets and assessed the possibility of indirect evaluation of pelletizing quality by the amount of mixture, which has not entered into the pelletation process. Confirmed experimentally were the dependence of dragee shell strength on several factors, such as rotation frequency and tilt angle of a working tool, moisture and feed mode of initial mixtures, the duration of seed pelletizing with a diatomaceous sand mixture, as well as the mixture composition at the second stage of pelletizing. As a result of screening experiment, it was found that the amount of mixture not involved in the pelletazing process is significantly affected by the humidity of the initial mixtures, the rotation frequency of the working body and the duration of pelletizing with a diatomaceous sand mixture. The search for the region of optimum parameters of pelletizing was made by the Box-Wilson method of steep ascent. The response surface area was described by the segment of Taylor's series, according to the coefficients of which it was found that that the best result is achieved with the initial mixture humidity of 7%, the rotation frequency of the working unit of 16 m^-1 and the duration of the first phase of seed pelletazing with a diatomaceous-sandy mixture of 18 minutes.