Hatch, a leading global engineering organization, has a reputation for the successful scale-up of process technology and the implementation of innovative solutions to technical challenges. To fulfill this reputation, Hatch’s Non-Ferrous Metals Technology Group uses advanced analytical tools, in particular CFD, for design evaluation and optimization, scale-up analysis and problem solving, where heat transfer, fluid flow, combustion and mass transfer are critical issues.

Recently we confronted the problem of scale-up analysis of a multiphase grinding mill – essentially a multiphase turbomachine! The mill works by vigorously “stirring” the feed material (pulp) and a coarse solid grinding media using a series of concentric disks rotating at high speed. At the discharge, a stationary separator is used to allow the pulp to flow out of the mill while retaining the grinding media. The essential features of the problem, from a modeling perspective were: complex geometry; multiple frames of reference (rotating disks and a stationary outlet), and a multiphase flow. As an added complication, the flow is strongly swirling with tangential velocities nearly three orders of magnitude greater than the mean axial velocity through the mill; this seemed like a perfect fit (or worthy challenge) for the new capabilities of CFX-5.