Christian Zybill, Erich Schubrikoff, Rainer Schneider and Marco Kursch

Efficient clay grinding with cast-metal components

Photos/Fotos: Karl Buch

»1 Pan mill runner ring with conical pusher pockets

Photos/Fotos: Karl Buch

»2 Pan mill geometry

»3 Roller shell with cylindrical seating ribs

»4 Force acting on particles entering a rolling mill

»5 “White-solidified“ ledeburitic microstructure of chilled cast iron alloy; martensitic matrix with cementite Fe₃C

»6 Microstructural profile of chilled cast iron, normal to surface

»7 Hardness profile of chilled cast iron with a “white“ chill depth of approx. 20 mm

»8 Scanning electron micrograph of the microstructure of chromium alloy cast iron

»9 Dressed core of a runner ring

»10 Mould configuration with outer chilled mould for casting a runner ring

»11 As-cast runner ring

»12 Runner ring with machined rims

»13 Fully machined runner ring

»14 Conceptual diagram of a centrifugal casting plant

»15 Unworked compound casting of chromium alloy cast iron/grey cast iron

In any clay grinding process, efficiency is an important criterion. In that connection, cast grinding tools are tried and proven as robust and cost-effective. This contribution deals with the application ranges of various cast materials in the grinding of clay and discusses their respective properties in order to give users as optimal a choice of grinding tools as possible [1].

1 Introduction

In clay grinding, where costs and fracture safety are the primary selection criteria, most non-metallic mineral substances are comminuted using hard-wearing cast-metal components.

In the simplest case, rough grinding takes place in a pan mill, while most fine grinding is attended to in roller mills.

2 Grinding process

2.1 Coarse grinding

When clay is wet-ground in a pan mill, the cylindrical rolling elements revolve on a grinding track, or pan, breaking down the product by a combination of pressure (runner weight) and friction as they pass over it. The friction results from the...