Modelling of pilot scale vertical roller mill operated in overflow mode

Abstract

Pilot scale grinding tests were performed for various materials by a mobile unit for modelling studies. Vertical roller mill was separated into the two section as grinding and separation. Grinding operation was defined by population balance model and breakage rate was correlated with specific grinding force, material index determined by compressed bed breakage tests and surface area of grinding table feed. For the modelling of separation section, obtained data were fitted to efficiency curve approach and model parameters were back calculated. Relationships of these parameters with operational conditions were investigated. As a first model parameter by pass fraction of was correlated with dust load of the separator feed. Then, by pass fraction was defined as a function of the dust load of the separator feed and material density. The ratio of air speed and rotor speed was correlated with corrected cut size and density effect was reflected to the model.