Comminution of pulverulent material by fluid energy

Abstract

A fluid energy grinding mill having a hollow vessel providing a central cylindrical core zone and a peripheral annular zone both disposed beyond a grinding zone at one end of the vessel. Carrier medium is injected into the grinding zone to generate a vertically-flowing vortex in the core zone. At the other end of the vessel, a first portion of the flow from the vortex is recirculated in a counter flow through an annular peripheral zone surrounding the core zone to interface with injected carrier medium in a grinding zone. A second portion is discharged through a central opening in the other end of the vessel. Particulate material is fed into the recirculating flow so that it may be comminuted in the grinding zone. In the vortex, the particulate material is classified by centrifugal action and the coarse particles are recirculated. The particles ground to the desired mass are discharged with the second portion of the carrier medium which is not recirculated. Several forms of regulation are disclosed for regulating the upwardly-flowing vortex and the portion of the flow which is recirculated. Guide means and deflectors are disclosed to assist in directing the particulate material to follow the desired path.