Computer Simulation of Clinker Grinding Circuits of Ardabil Cement Plant

Multi-compartment tube mills in closed circuit with air separators are widely used for clinker grinding in cement plants. Ardabil cement plant which produces a pozzolanic type of cement is also using such closed grinding circuits for comminution of clinker, pozzolan and gypsum mixtures with specific ratios to produce cement powder. To simulate grinding circuits of this plant, a large number of samples were collected from various existing streams. In addition, samples were collected from inside of the mills at evenly spaced locations on their longitudinal axis. Then, particle size distribution of samples were determined using sieve analysis and laser diffraction methods and were mass balanced using streams flow rates. The work index and breakage distribution function of mill feed (mixture of clinker, pozzolan and gypsum) were determined in laboratory. These data were used for calibration of simulation models. For circuit simulations, BMCS (BMCS-based Modular Comminution Simulator) software was used which is capable of simulating various comminution circuits. In this article, mathematical models of ball mill and efficiency curve were used for simulation of tube mills and efficiency curve for simulation of air separators. BMCS program for simulation of tube mills uses a population balance model for mathematical description of breakage process and tanks-in-series model for mathematical description of residence time distribution.Also, for simulation of diaphragms and air separator BMCS uses Whiten model for mathematical description of efficiency curve. Whiten model parameters were determined using GA toolbox of MATLAB software. Close agreement between simulation results and actual data indicate accuracy of sampling procedure, validity of models and their calibration and accuracy of predictions made by simulator.