A system and method for online estimate of the filling level of balls and loading level in a rotary mills, comprising a set of vibration sensors unit, associated with a magnet to transmit data signals via an antenna to a receiver that receives data signals from the antenna, an antenna, wherein the receiver is connected via optical fiber to a signal processor, which in turn communicates to a control server via a UTP cable, wherein the control server also obtains data from the mill operation to determine the best filling of balls and load; and the operating method.
