e-Περιοδικό Επιστήμης & Τεχνολογίας e-Journal of Science & Technology (e-JST) http://e-jst.teiath.gr 39 INVESTIGATION OF FEED DYNAMICS IN CLINKER GRINDING MILL BY RESIDENCE TIME DISTRIBUTION METHOD Simon Yao Adzaklo 1, *, Christian Priesly Kofi Dagadu 1 , Patience Serwaah Adu 1 , Hannah Asamoah Affum 1 , Bright Jerry Atsu Yao Sogbey 1 1 National Nuclear Research Institute, Ghana Atomic Energy Commission, P. O. Box LG 80, Legon-Accra, *s.yadzaklo@gaecgh.org Abstract Residence time distribution (RTD) analysis has been identified as one of the best experimental and classical tools for studying the performance of non-ideal chemical reactors and industrial circuits. In this study, RTD method was used to investigate feed dynamics in clinker grinding mill. The data was collected by introducing 40mCi Au- 198 as a tracer in the feed at the mill inlet. The gamma signal was determined with thallium activated NaI detector placed at the mill outlet. RTD curve of the mill was generated from which the mean residence time (MRT) was evaluated using the method of moments. The experimental MRT was 27.1 minutes and the theoretical MRT evaluated from plant parameters was 55.3 minutes. Mathematical models were used to fit the outlet tracer concentration signal of the experimental data. The feed dynamics in the mill was best described by the “perfect mixing cells in series with exchange’ model which fitted well with the experimental outlet response curves of the mill. Keywords: Clinker, dynamics, Feed, mill, residence, time. 1.0 INTRODUCTION The main raw material for cement production is clinker. Cement clinker is usually grounded using a ball mill. This is essentially a large rotating drum containing grinding media; normally steel balls. As the drum rotates, the balls cascade and crush the clinker. Fig. 1 shows the internals of a typical grinding mill. Approximately 95% of the feed to the cement grinding circuit is clinker made up of four basic oxides: calcium oxide, siliconoxide, aluminium oxide and iron oxide. A small amount of gypsum is added to control the set properties of the produced cement. It is quite typical to add a certain amount of water and small quantities of organic grinding aids to control mill temperature and facilitate the pulverization process (Zhang & Napier-Munn 1995). Fig. 1. Internal view of clinker grinding mill