Abstract: An electric motor operated rotary drum type grinding mill is operated at optimal efficiency by detecting and analyzing the motor current. The power signals are converted by signal processing equipment for presentation as pictorial display representations of mill operating conditions at a variety of motor current levels to permit unskilled operators to understand the current operating conditions. Instantaneous on line current signals are derived from the mill by a transformer coupling without rewiring or modification. Analytical equipment processes the detected current signals for mill control, storage of historical performance and pictorial display. Mill operation is accordingly controlled in semi-automatic or fully automatic modes that maintain optimum mill efficiency.

Abstract: Computerized control of a grinding mill complex to establish a predetermined optomized operating setpoint condition in the presence of chemical additive grinding aids responds to a plurality of input signals representative of mill operating characteristics and controls a plurality of input feed materials for establishing the setpoint condition. Provision is made for accelerating correction when deviations from optimum are large. A prioritized selection of input signals serves to first control mill conditions that could damage elevator motors, or the like. Control signals are derived as a function of error deviations for more effective control and are normalized for lag time. The system combines an arithmetic computer with a multiplexing computer that scans and organizes correction control signals and provides for communication with external computers.

Abstract: A current transformer is coupled about the power feed line of the motor operating a ball mill grinder or the like to sense the motor current. This current is converted to a motor load or horsepower signal which is processed together with mill flow rate information of both raw materials and additives such as chemicals for improving grinding efficiency. Thus, signals representative of mill operating efficiency are derived, and displayed in visual form having a relationship to internal mill conditions and optimum mill operating efficiency. Also the sampled signals are sampled and stored in digital form in a computer memory and in a tape recorder for processing and recall. The samples are identified by a recorded time signal.