Wet rolling stones: Growth of a granular aggregate under flow

Pierre Jop,Alban Sauret,Guillaume Saingier,M.A Aguirre,R Soto,S Luding,L.A Pugnaloni

doi:10.1051/epjconf/202124909012

Abstract

Wet granulation processes can be driven from low to high water content. In this study, we consider the model situation of the growth of a single wet aggregate rolling in a dry granular flow inside a rotating drum. We measure the time evolution of its diameter for different grains and liquids, as well as various rotation rates of the drum. Using X-ray tomography, we are able to characterize the internal structure of the granular aggregate at different times during the process. We show that the growth rate of the aggregate can be related to the transport of the liquid inside the granule and the capture of grains. We propose a model to rationalize the maximum size of the aggregate and its growth rate.

Highlights

Wet granulation processes can be driven from low to high water content
We focus on an isolated wet aggregate during
We characterized the growth of an aggregate, initially saturated in liquid, in a gentle granular flow

Summary

Introduction

Blending dry grains and liquid is a common step of many industrial processes. When the volume of liquid is small compared to the volume of grains, wet aggregates are created. (c) considered the static properties of wet granular material, the dynamical situation where grains and liquid are blend together remains more elusive. 2 Experiments: growth dynamics of the wet aggregate in a rotating drum properties of an individual aggregate during its evolution. An aggregate is prepared by depositing a drop of aqueous solution of ZnI2 or glycerol on the surface of the sand before starting the rotation [Fig. 1(c)] This method allows us to create an initial aggregate fully saturated with liquid. To test if the spontaneous capillary spreading of the liquid toward new dry grains plays a key role, we report the time evolution of the mass of the same initial aggregate buried in the sand but without flow. This behavior suggests that the evolution of the aggregate can be rescaled by the initial volume of liquid, and the transport of the liquid may be the key parameter

Microstructure of the aggregate during its evolution

Model: Growth dynamics through the transport of liquid

Beyond the growth: erosion of the aggregate

Findings

Conclusion