LOCATION OF THE BALL IN A MILL

We have repeatedly noted the fact that the company Energosteel constantly conducts comprehensive measures to improve the quality characteristics of the products produced. In this regard, we constantly offer our customers the industrial testing based on their production. As a rule, these are industrial tests that are carried out in ball mills on the production base of our partners. Thus, we are conducting four full-scale experiments currently. In the near future two more tests will start, supplies of grinding media for which have already been carried out.

We would like to note that we are constantly in contact with the technical specialists of our partners in order to get feedback on the quality of our products. During the experiments, in addition to telephone contact, our specialists visit the client, jointly conduct a visual inspection of the grinding media state, carry out instrumental measurements to determine the specific consumption of the tested balls. Over the past five months of 2019, we are faced with a situation where the grinding balls in the mill (when stopped) aren’t set right in terms of the grinding process  effectiveness. Let’s look at this question in more detail.

Thus, to obtain high-quality grinding, the ball in the mill should be located as follows: at the beginning of the mill (in nutrition), there must be balls of maximum diameter, because it is necessary to expend large energy to destroy the largest pieces (particles) of the material. In the center of the mill must be medium diameter balls, because the stage of primary grinding has already passed. At the exit of the mill, for the final regrinding of the material, small diameter balls are necessary. Also, at the end of the mill, the entire waste balls (scrap) are concentrated, which gradually “leaves” the mill through the openings of the discharge grid.

Such placement of grinding balls in the mill is provided by the following factors:

1. The ball mill is installed correctly (no horizontal tilt angles);
2. The steam mill is stationary, no vibration;
3. The mill operation mode is properly selected (the speed of drum rotation );
4. The lining of the inner walls of the ball mill drum is correctly selected and installed;
5. Full observance with the technological mode of grinding (productivity of the mill, density regimes with wet grinding, the rate of loading of the mill with grinding bodies, etc.);
6. The assembly of grinding bodies loaded into the mill is correctly selected.

The result of the improper location of the grinding bodies in the mill can be:

• an increase in the specific consumption of grinding;
• the deterioration of the grinding quality, which automatically leads to a decrease in the mill productivity, and therefore to an increase in the specific consumption of grinding bodies;
• an increase in electricity consumption, which is necessary for grinding material;
• the lifespan reducing  of the inner drum lining, etc.

Thus, a few of our cooperating partners faced a similar problem in 2019. We held a number of consultations on this issue with specialized scientific and technical institutes, manufacturers of armored plates and manufacturers of mills. The following reasons of the grinding balls incorrect location in a ball mill were identified  based on existing work:

• the presence of the mill vibration;
• the different types mixture of grinding media (cylpebs and ball);
• the change of the grinding density mode when wet grinding;
• the presence of the ball mill inclination;
• the type of armor lining is incorrectly selected.

Thus, to ensure the proper operation of the ball mill, we recommend our customers to strictly observe the required parameters (conditions) of operation, which are spelt out in the technical documentation for the ball mill. When making any constructive or technological changes, it is necessary comprehensively to assess the possible consequences of these changes.

We hope this information will be useful to our readers. We will continue to inform you  about the various nuances of the grinding process.