Vertical Agitated Media Mill scale-up and simulation

• The vertical mill product size distribution was predicted by breakage parameters.
• The vertical mill breakage mechanisms are the same that observed in ball mills.
• Breakage mechanism by attrition or abrasion is not favored in vertical mills.
• The vertical mill efficiency factor equal 1.35 worked well for all samples tested.
• It is possible to scale-up pilot vertical mills from batch tube mill tests.

Vertical Agitated Media Mill modeling has become subject of a research project due to its potential application as a secondary grinding mill as well as regrind and pellet feed preparation projects. A test campaign with a pilot scale vertical mill was carried out with five different ore samples to elaborate a simple and robust methodology to scale-up vertical mills and perform simulations. The methodology proposed considers breakage parameters determined from tests in a conventional batch ball mill and population balance model for simulations. The tests can be performed very quickly in any process laboratory with a small quantity of sample. Two different models can be used for scale-up purposes: the first is based on the specific grinding energy and the corresponding tests were carried out on samples with natural size distribution. The second is based on particle residence time distribution and the tests carried out with narrow sized particles. Breakage and selection function parameters were estimated from each test procedure. The results indicate that it is possible to perform vertical mill scale-up and simulations with acceptable accuracy using the results from laboratory ball mill tests. The data analysis showed that the ratio of grinding net powers between ball and vertical mills is approximately 1.35 for all samples tested.