Construction of Transfer Function Model for Cement Closed Grinding Circuit. A study on robust control in closed grinding circuit (1st Report).

Cement grinding process control recently requires not only to reduce the specific energy consumption and to stabilize the process but also to improve the final product quality. To achieve these requirements, detailed modelling of the process becomes necessary. However, in most cases the identification model (‘black-box’ model), derived from input/output behaviors of the process, has been used because of complexity of the process.The authors have carried out the construction of transfer function models based on population balance model of the process. Firstly, the exact transfer function model based on these dynamic model was proposed by using computer software, MATLAB. Secondly, to consider the reduction of the exact model's order and the construction of the transfer function introducing the cut size as an input variable, the simplified model was proposed for the exact one. As the transfer function model of specific surface area as an output variable, the approximated model was obtained by taking account of simulation results and steady-state conditions.The responses obtained by these simplified models coincided well with those by exact model.