sponge iron industry –past-present-future - SIMA

advantages over the conventional heavy media
cyclones. It is an ideal technology for the high ash
& high NGM Indian coals. The Tri-Flo ® has a very
high sink capacity and produces three products in
one vessel, thus improving separation efficiency,
simplifying plant layout i.e. requiring less space and
reducing overall capital costs. Additionally, in this
system the material is fed at an atmospheric
pressure separately from the dense medium.
This results in very low wear & tear compared to
conventional heavy media system and thus resulting
in reduced overall operating costs.
The Tri-Flo is a proven technology with more than
30 nos. commercial plants operating worldwide
mainly in mineral processing. This technology is now
attracting the interest of coal beneficiation plant
operators and designers due to its unique features
that better deal with the problems posed by modern
coal mining methods, lower run-of-mines (ROM)
quality and rejects rewashing. The Indian non-coking
coals have a very high range of quality variation in
feed. The Tri-Flo ® Technology with a double stage
separation can better adapt to the Indian coals and
provide a more consistent product at higher yields
with reduced wear & tear and thus resulting in better
plant availability.
Allmineral | Asia having additionally dry jigging
technology (Allair ® ) and wet jigging technology
(Alljig ® ), has already made deep in roads into the
Indian Mineral beneficiation market. With the Tri-
Flo ® technology in its bag, it is the only company
in India to offer such a varied range of
technologies to the Indian coal and minerals
industry.
Advantages of Tri-Flo Technology
The Tri-Flo technology has numerous advantages
over the competitors’ technologies. Advantages
are reported below.
Two, Three, or More Product from One Vessel
The Tri-Flo is a multistage separator in one vessel
with reduced capital cost (buildings, piping, etc.) and
operating cost, if compared with the same multiple
density traditional circuit. The Tri-Flo rewashes the
float stream of the previous stage where the
separation is repeated and operates like a rougher-
cleaner in coal preparation or as a rougherscavenger
in ore separation.
The second or following stage can be:
l A final bye-product (i.e. premium coal, power plant
coal, and rejects)
l Comminuted to improve the liberation and reprocessed
for increased recovery
l Re-circulated to head feed for sharper separation
in difficult applications
Energy cost of pumping is reduced by up to 50% if
compared with traditional double stage installations.
Reprocessing the Float Material Gives Better
Results Than Reprocessing the Heavy Material
Tri-Flo - Heavy material must travel from the centre
to the wall of the separator to be discharged and the
misplaced coal to rejects is minimal. On the contrary
the float is discharged from the centre of the
separator on the same axe where it is fed and might
contain some misplaced heavy material due to
various reasons (overloading the separator, changed
conditions in the feed characteristics, etc.). In case
of overloading of the first stage, the second stage is
fed with the first stage light material and the majority
of the heavy material has been already rejected,
making the conditions in the second stage more
stable and allowing to reject the misplaced material.
Other Technologies – Other technologies, derived
from the British Coal Board (Larcodems and similar)
have the possibility to rewash the heavy material in
a second stage. If the first stage is overloaded low
quality light product is produced and lower densities
are required to obtain the target product misplacing
to rejects the more profitable premium coal which
will be discharged as power plant product with
significant economical losses as proved in many
applications.
Reprocessing the light material gives better overall
performance because each size fraction is separated
at more or less the same density, instead
reprocessing the heavy material provides density
cuts that are progressively higher as the particle size
decreases with obvious economical losses .
JANUARY-2011/34