Cradle to grave
Cleaner coal with new spiral
New “low cut” spiral technology can result in
cleaner coal with less waste being achieved in
a single stage. Ultimately this reduces capital
costs as no further spiral stages are required for
cleaning down the line. This according to Faan
Bornman, technology manager at Multotec.
Bornman says that Multotec’s SX10 low
density spiral’s reduced cut point of 1.55g/cm3
The first off-take removes ash. This opens
the available separation surface of the spiral,
allowing the remaining material to separate
more easily, separating clean coal from less-
clean coal.
The low-density spiral is essentially a
primary and secondary stage on one centre
column. Rejects are discarded into the
centre column and the remaining product
is repulped before being sent to a secondary
off-take.
Facilitating the two off-takes is a longer
spiral on the Multotec SX10. This increases
the residence time and gives the particles
sufficient time to separate.
delivers considerable advantages over the cut
points of between 1.6 and 1.8g/cm3 typically
achieved in the industry today.
“The approach taken with the Multotec
SX10 spiral is to remove the gangue, or
mineral containing particles, from the trough
in two off-takes,” says Bornman.
Depending on the setting of the product
box splitters, this new spiral has the ability
to produce a thermal coal and a coking
coal on one spiral. Bornman says this was
proven through test work done in the USA.
The two offtakes enable the removal of
most of the gangue leaving a middlings and
cleaner coal products to be collected at the
dart splitters.
Experimental work was carried out using
coal from two South African collieries as well
as doing site test work in the US. Promising
results were obtained leading to the first
order for Multotec SX10 spirals from a
North America-based mine.
The first off-take of the Multotec SX10 removes ash.
The two off-takes on the Multotec SX10 leave cleaner coal products to be
collected at the dart splitters.
Furnaces in the steelmaking, glass, or
general manufacturing industries have a
finite lifetime before requiring significant
maintenance and repair work. Jet owns
specialised machines and equipment
modified to work within the confined space
of a furnace structure.
“These specialised machines offer us
the best chance of improving on project
schedules, resulting in decreased downtime
for our clients,” says Kate Bester, contracts
manager at Jet Demolition.
The company can transition seamlessly
from stave-jacking to lancing and to
mechanised removal of massive blocks
of solidified iron. “Furnace shutdowns
are normally planned during cold winter
months and will be on a 24-hour schedule
to minimise production downtime. It is thus
the strength, commitment, and discipline of
the team that results in a highly successful
project completed within time and without
incident,” Bester explains.
The elements that require demolition
depend on the extent of the maintenance
or repair work to be undertaken. Smaller,
less serious shutdowns often require only
[36] MINING MIRROR AUGUST 2019
Bringing down the house
Demolition of redundant electrode from within furnace.
the burden and solidified product from within
the furnace to be removed, to enable localised
repairs to the refractory and/or insulation
lining. Other extensive repairs may call
for the demolition and removal of the
refractory lining, sections of the shell-plate,
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