Grindability Test Modelling, Measurement and Mill Fingerpriniting

Executive Summary

of the proposed DEM-PBM multiscale method for the optimization of milling devices.

predictions of product size distribution is achieved, which indicates a promising application

experiments at different rotary speeds. A good agreement between the tests and the

model was then used to predict the milling outcomes for the other three set of milling

12000RPM using a constraint optimisation technique. The DEM-PBM coupled multiscale

i.e. particle material dependent parameters, were evaluated from the milling test at

parameters and mill operating dependent parameters. The remaining parameters of PBM,

scale. Variables in the PBM kernel were classified into particle materials dependent

operating dependent parameters in the Population Balance Model (PBM) at the process

velocity distributions obtained through DEM simulations were utilized to inform the mill

the particle dynamic and stressing conditions inside the pin mill. Furthermore, the impact

and feed rate. DEM simulations were then performed to understand the fundamentals of

The UPZ100 pin mill experiments were conducted to study the effect of rotary speed

Timoshenko beam theory considering axial, shear and bending behaviour of the bond.

model by Brown et al. (2014) was utilized in which the bond contact is based on

which is then compared to experimental results. A recently developed new bonded contact

breakage subject to impact loading was conducted to evaluate the breakage propensity

of numerical results. A Discrete Element Method (DEM) simulation of single particle

comminution characteristics of the test solids, which provides the basis for the validation

experiments were carried out using the UPZ100 impact pin mill to measure the

component to be rationalized. In particular, the contribution of tangential component velocity was incorporated in the new model using the mobilized dynamic friction. Milling

a new breakage model, which enables the contribution of the normal and tangential velocity

velocity identified from experiment, the effect of impact angle is considered in developing

in predicting breakage under oblique impact and the significance of tangential component

crack accounts for the chipping mechanism. Considering the limitation of existing models

velocity. A new particle breakage model was proposed assuming that the subsurface lateral

velocity plays an increasingly important role in particle breakage with increasing impact

impact tests. It was found from the zeolite particle impact test that tangential component

by single particle loading experiments, including indentation tests and single particle

elucidate the particle breakage mechanics. The material grindability was first investigated

A hybrid of experimental, theoretical and numerical methods have been adopted to

particle breakage model calibrated against the defined grindability.

etc. pertaining to a milling process, which in turn will provide the basis for an improved

capable of analysing particle breakage subjected to particle impact, compression, and shear

provide the fundamental scientific basis for developing appropriate grindability measure

and how they relate to the mechanical properties and the final size distribution. This will

fracture and breakage mechanisms of individual particles under different loading regimes,

stressing events. The material grindability will require a detailed study of the fundamental

prevail in a milling operation and establishing material grindability in the context of the

in mill performance optimization. This involves characterizing the stressing events that

grindability with particle dynamics in a mill in order to provide an innovative step-change

reduction. In this project, we aim to develop new ideas and methodologies to link material

Milling is commonly deployed in many industrial sectors for intended particle size