Correct mill liner design can affect the efficiency and the life expectancy of a mill. Some of the most commonly seen problems in these machines are premature wear and shell damage caused by impacts of the charge on the liner.
Such issues could lead to early failures and shorter equipment life.
Rocky DEM is a powerful tool that can predict charge motion easily and accurately, allowing for proper selection of rotational mill velocity and liner profiles. This can reduce the effect of impacts caused by the charge on the liner.
Wear can also be modeled within Rocky DEM without the need to couple with any other software, easily and conveniently helping you predict the life of a mill liner.
In a study presented in Iran, MGM Group showed how Rocky DEM modeled the profile for further manufacture of mill linings.
The workflow was a loop that began with obtaining information from a client, then using the data for simulations in Rocky.
Through the analysis of these simulations, potential design improvements were discovered, and suggestions were incorporated into the equipment manufacturing.
Later, results from operating the equipment can then be used to feed back into the model and optimize mill linings, as shown in the chart below:
Throughout the development of this project, MGM Group realized several benefits to using Rocky DEM to simulate ballistics and determine the optimum lining profile:
• Rocky DEM allows engineers to determine the lining profile and the optimum ballistics inside the mill;
• Rocky DEM provides a wide variety of data for deep analysis: impact loads, abrasion of the lining, and ballistics change during lining wearing;
• Rocky DEM distinguishes the ballistics of specific elements; for example, engineers can assess the ballistics of different grinding media sizes.
From these Rocky DEM simulations, engineers discovered the advantages of using modified pulp lifters:
• Decreasing the wearing of pulp lifters;
• Decreasing power consumption between 10 and 15%; and
• Increasing mill efficiency between 10 and 15%.
A few constraints must be taken into account when developing new drawings for further manufacturing. The new drawings must:
• Consider installation limitations;
• Be based on simulation results;
• Be based on the experience of MGM Group relining team; and
• Be approved by the relining machine manufacturing.
The images below show some examples of new drawings based on the results from Rocky DEM and MGM Group’s experiences:
The advanced computational methods implemented in Rocky DEM allow the prediction of worn liner profiles and ballistics in mills. This information can be used to optimize the overall performance of the mill from an efficiency and power consumption perspective. As the mill liners get worn, the change of the charge trajectories, energy transfer, and milling efficiency are taken into account in the simulations, which is a very helpful tool in decision making new mill liner designs.