Respected Sir, please tell me about how to decide the velocity at mill

Damring height in  VRM depends on retention time of material on tabe. which is indicate by  mill vibration and accepting grinding force with respect to main drive load.It is adjusted on the basic of  grinding process.Normaly its kept 2.0 % of table dia.But material is too fine in vrm  will more than 2.0 % (2.2 to 2.5 %)

GKS

From our experience on Feiffer VRM (raw mill), the dam ring hight is 3% of the diameter of the rotating table.