DISPOSAL OF MUD and ash, particularly in wet weather conditions, is a significant
expense for mills. This paper reports on part of a process to pelletise mud and ash,
aimed at making mud and ash more attractive to growers across entire mill districts. The
full process and the re-constituting and centrifuging rotary vacuum filter mud part of the
process were described in two papers to the 2011 conference. The component described
in this paper involves aspects of mixing mud and ash with subsequent drying using
boiler exit gas. The mud material needs to mix easily with boiler ash and the mixture
has to feed easily into and be pneumatically conveyed by a flue gas dryer. The
performance of a pilot flue gas dryer for drying mud and ash was evaluated. The mud
and ash mixture was found to dry much faster than final bagasse, provided the mud and
ash material was broken up into individual particles. A previously developed computer
model of bagasse drying was updated to take into account the smaller particle size of the
mud and ash mixture. This upgraded model predicted the performance of the pilot flue
gas dryer well.