Charge Behavior Analysis in Ball Mill by Using Estimated Torque

The aim of this paper is to present a method to analyze the dynamic of the charge in a ball mill. The method is based on the mill torque estimated from angular position and motor electrical signals. The estimated torque signal obtained from a Luenberguer velocity observer is bandpass filtered to isolate the mill-filling-related component. The root-mean-square value of this component, used as an indication variable, is correlated to vibration signal measured through an accelerometer in order to check the validity of the proposed method. The proposed method does not need any sensor be installed directly on the mill and requires only sensors usually available for motor control purposes in frequency inverter drives.