Three Roll Mill - Ross MixersFor example; the feed roll may rotate at 30 rpm, the center roll at 90 rpm and the apron roll at 270 rpm. Material is transferred from the center roll to the apron roll by . View Specifications. To request a brochure for the Three Roll Mill, please completely fill out the following form. You will then have access to download the.specifiion of vertical three roller mills,Vertical Roller Mill Manufacturer, Roller Mill Machine, Best Price for .Vertical Roller Mill Manufacturer. The Strommachina brand roller mills are a very reliable, powerful and efficient type of the milling equipment. The unique feature of the roller mills is their multi-functionality: three process operations are combined in this unit, in particular: drying, milling, separation. The roller mills are a 3-in-1.