In an oligopoly, technological decisions may be subordinated to economical requirements, even though this statement could infer a departure from the technological optimality. Therefore, Nash equilibrium should be found in order to bridge both sides, i.e. technological and economical and this constitutes the subject of the paper. Single and repetitive games for identical players are modeled here for closed-circuit cement grinding plants. Models are simple, open and versatile and can be easily solved.