international
construction
may 2014
DEMOLTION&RECYCLING
54
Cutting-edge techniques
T
he latest addition toDurham, UK-basedMGLDemolition’s
fleet is aQJ341 tracked jaw crusher from Sandvik
construction.
Managing director, MarkDavison said, “One of the
distinct advantages of theQJ341 is that due to its inherent
transportability from site to site, andmanoeuvrability around
the site, it is literally able to go direct to thematerial, and
reduce it for reuse on-site. This not only providesmaterial for
use straight away, but reduces haulage costs, aswell as being
environmentally sustainable.”
The company’s newQJ341 is currently being used to crush
-75mm demolitionmaterial on a variety of projects. Key
features include its 1200 x 750mm feed opening, hydraulically
adjustable closed side setting, high reduction ratios and a
reverse crushing action to relieve blockages, plus an automatic
central lubrication system.
MGLDemolition’s QJ341 also features a load control system
for the feeder drive, level sensor fitted to the jaw, and speed
wheel fitted to themain conveyor. One of the key design
changes now sees themain conveyor being fittedwith a raise
and lower facility for increasedmagnet clearance together with
ease of transportation.
Giant cats
German sales successes for 29mmachines
Crusher addition
UK contractor adds new tracked jaw
G
erman
Cat dealer
Zeppelin
has reportedly
sold four 349E
UHD high reaches
to demolition
contractors around
Germany. The
machines have
pin heights of 29
m, can carry a 3
tonne tool at that
height and feature
hydraulic extending
undercarriages.
There is a
hydraulic boom
coupling system and
all the all hydraulic
hoses have quick
couplings, allowing
boom changes to
bemade in just 10minutes. Dutchmodifier STC conducted the
engineering design of the boom and hydraulic systems, with all
fabricationwork and hydraulic system production carried out at
its facility inCoevorden, theNetherlands.
DEMOLITION &
RECYCLING INTERNATIONAL
AKHLGroup publication
Explosive
demolition
VOLUME 16
NUMBER 2
MARCH-APRIL2014
Crushing
& screening
after the implosion for ease of sorting and
recycling. Following the soft strip, screens
were positioned around the outside of
everyfloor thatwouldhave charges placed
in them to guard against flying debris.
The implosion sequence of the
supporting columns was designed based
on a simulation by Applied Science
International (ASI). The concept was to
keep the implosion in the centre of the
buildings, rather than towards the edges,
to cause them to fall inwards and away
from surrounding obstructions.
Other measures were taken, such as the
use of steel cables in the second building
to ensure that the structure’s water tank
did not fall towards an adjacent flower
shop.
When it came to the implosion, delays
of 300 milliseconds were set up between
the blasts on each set of columns, starting
at the centre of the building, with the
perimeter columns the last to go. In fact, some of the perimeter
columns were not blasted to help ensure all the debris remained
on the existing buildings’ footprint.
Thecharge ratioof the implosionwas0.300kgperm
3
of column
volume. This ratio prevented any fragments from penetrating
the screens and hitting other buildings in the vicinity. A total of
130kgof explosiveswas used, spreadover 1,200manuallydrilled
holes.
The implosion was carried out at 8:00 am on November 2,
2012. No power cables were damaged during the event, and in
additionno cracks in anyof the adjacent buildingswereobserved,
while all the debris from the implosion was contained inside
the building footprint, as predicted by the engineers behind the
project.The peak particle velocity recorded by seismographs was
below 3mm/s, whichwas safely below themaximum limit of 15
mm/s allowedunder Brazilian standards.
This all illustrates how sophisticated the demolition industry is,
be it through scientifically engineered explosive demolition, or
the latest inflexible demolitionmachines.
iC
Demolition&Recycling International
is amagazine for
the global demolition industry. Formore information,
including how to arrange a FREE subscription, please visit
One of Montabert’s latest additions is
the 501 NG, a name that references a
famous product for the company, the
BRH 501 breaker launched in 1969. The
newmodel features an energy recovery
system and blank-fire protection.
