Research on locating control method of ball mill based on prediction
To solve the difficulty of precise locating of large inertia ball mill, a new method based on prediction is put forward. The feasibility of this method was analyzed using the motor theory and analysis on the ball mill kinematics and dynamics. The equipment to install rotary encoder that was connected to the ball mill was designed. And the testing hard ware based on single-chip microcomputer was build, and data of the angle and the rotational speed of the ball mill were acquired. With the tool of Mat lab, data were analyzed. The results shows that the angle predicted from the starting stage is very much closed to the angle which is measured, and the tolerance is very small, and it can meet the application completely.
Research on precise locating control of large inertia ball mill
To solve the problem of difficulty in precise locating of batch ball mill, the kinetic model was build, and parameters relationship between starting and shutting down were analyzed, control system was designed. At the stage of starting of ball mill, load torque, rotary inertia and so on could be acquired. Based on the relationship of ball mill kinetic parameters between starting and shutting off, parameters at the stage of shutting off could be predicted. With these parameters, the angle that the ball mill would roll after power off could be predicted. With the angle, the optimum spot to cut off power of ball mill could be find, and precise locating and stopping of ball mill could be implemented. The control system is simple in structure, easy for installation and suitable for the reconstruction of existing ball mills control.
Ball mill simulation in wet grinding using a tumbling mill and its correlation to grinding rate
A method for simulating the motion of balls in tumbling ball mill under wet condition is investigated. The simulation method is based on the three-dimensional discrete element method (DEM) and takes into account the effects of the presence of suspension, i.e., drag force and buoyancy. The impact energy on balls' collision, which enables us to provide useful information for predicting the grinding rate, was calculated from the simulation work. Actual ball motion in the suspension in the mill was observed through a transparent mill lid made of acrylic acid resin at different solid concentrations and the suspension was made of water with powder samples such as gibbsite, limestone and talc. Grinding tests of the gibbsite sample using two laboratory tumbling ball mills made of stainless steel and using alumina with balls made of steel, alumina and glass were conducted and the grinding rate was determined by measuring the 50% particle size of the product. The specific impact energy calculated from the simulation work correlates well with the grinding rate of the sample, irrespective of the grinding conditions, so that the energy is the key factor controlling the grinding phenomena in wet milling.