First of all, these photos prove beyond any doubt the molten metal is aluminum.
Secondly, there were reports of aluminum.
NY TIMES NEWS SERVICE , NEW YORK
But the fires continued to burn. Black smoke poured from shattered windows on floor after floor, fresh oxygen sucked in from the gaping holes caused by the impacts. In the northeast corner of the building's 80th floor, where office furniture had been shoved by the plane, the fire burned so hot that a stream of molten metal began to pour over the side like a flaming waterfall.
The apparent source of this waterfall: molten aluminum from the airliner's wings and fuselage, which had also piled up in that corner. Within minutes, portions of the 80th floor began to give way, as evidenced by horizontal lines of dust blowing out of the side of the building. Seconds later, near the heavily damaged southeasterly portion of this same floor, close to where the aircraft had entered, exterior columns began to buckle.
Fifty-six minutes and 10 seconds after it was hit, the top of the south building tilted horribly, to the east and then to the south, and initiated the collapse of the entire tower, floor upon floor.
Was molten metal in the basements caused by demolitions materials?
...It was at least that hot at points within the pile that were away from the hottest zones. William Langewiesche, the only journalist who was allowed to go with the engineers in their explorations beneath the debris, writes in “American Ground: Un-building the World Trade Center” of a subterranean parking lot:
Along the north side, where the basement structure remained strong and intact (and was ulti-mately preserved), the fire had been so intense in places that it had consumed the tires and interiors, and had left hulks sitting on axles above hardened pools of aluminum wheels.
Dr. Shyam Sunder, lead investigator for NIST's building and fire safety investigation into the WTC disaster, said, "While the buildings were able to withstand the initial impact of the aircraft, the resulting fires that spread through the towers weakened support columns and floors that had fireproofing dislodged by the impacts. This eventually led to collapse as the perimeter columns were pulled inward by the sagging floors and buckled."
"The reason the towers collapsed is because the fireproofing was dislodged," according to Sunder. If the fireproofing had remained in place, Sunder said, the fires would have burned out and moved on without weakening key elements to the point of structural collapse."
Aluminum and the World Trade Center Disaster
Aluminum was present in two significant forms at the World Trade Center on 9-11:
(i) By far the largest source of aluminum at the WTC was the exterior cladding
on WTC 1 & 2. In quantitative terms it may be estimated that 2,000,000 kg of
anodized 0.09 aluminum sheet was used, in the form of 43,600 panels, to
cover the fa€ade of each Twin Tower.
(i) The other major source of aluminum at the WTC was the aluminum alloy
airframes of the Boeing 767 aircraft that crashed into the Twin Towers on the
morning of 9-11. It may be estimated that, on impact, these aircraft weighed
about 124,000 kg including fuel; of this weight, 46,000 kg comprised the
fuselage and 21,000 kg made up the mass of the wings – all of which were
fabricated from aluminum alloys. Modern airframes are invariably constructed
from series 2000 aluminum alloys.
Alloy 2024 is a typical example containing 93 % Al, 4.5 % Cu, 1.5 % Mg,
and 0.5 % each of Mn and Fe. These metallic additions to aluminum lower
the melting point of the alloy from a value of 660 C, for pure aluminum, to
about 548 C for alloy 2024. This relatively low temperature indicates that
the fires within the Twin Towers were quite capable of melting at least some
of the Boeing 767 aluminum airframe structures remaining in the WTC before
But is there any direct evidence for the presence of molten aluminum at the WTC site on
9-11? The answer to this question is an emphatic: “Yes!” The formation of molten
aluminum in WTC 2 just prior to its collapse was discussed in the well known FEMA and
NIST Reports on the performance of the WTC buildings during 9-11. Here are the
FEMA: World Trade Center Building Performance Study, Chapter
Boeing 767 aircraft separately strike WTC 1 & 2 and flaming wreckage becomes
lodged in the upper floors of each Tower.
Combustibles, such as office furniture, paper and plastic, start to burn, fuelled by at
least 10,00 liters of kerosene, and the temperature in the impact zone begins to rise.
After about 30 minutes, the fires subside, but black smoke continues to pour out of both
Towers showing that the fires are not “out”, but “smoldering”.
After about 40 minutes, parts of the airframe in WTC 2 approached the critical
temperature range of 500 - 550 C where aluminum alloys starts to soften and melt.
At 50 minutes, molten aluminum forms and starts to flow from the airframe in WTC 2.
The molten aluminum re-ignites some of the smoldering fires and rapidly burns through
other combustible materials that survived the initial conflagration. Molten aluminum also
falls onto fractured concrete, gypsum and rusted steel surfaces inducing violent thermite
explosions, dispersing globules of molten metal and igniting new fires.
The extreme heat generated by the molten aluminum rapidly weakens already damaged
steel columns and trusses in the impact zone causing local slumping and partial collapse.
The remains of the semi-molten airframe fall to the floor below and mix with fresh
combustible material, air, water, thermite reagents (crushed concrete, gypsum, rust), and
sections of aluminum cladding from the Tower’s fa€ade, initiating more explosions.
This sequence of events is now repeated in a rapidly accelerating, and increasingly
violent cascade of destruction. Gravity adds momentum to the downward acceleration of
the mass of debris and WTC 2 collapses in less than 16 seconds.
The burning aluminum remaining at the end of the collapse glows brightly for a
moment and illuminates the rising clouds of smoke and dust at ground zero.
About 25 minutes later, the temperature of the aircraft wreckage in WTC 1 reaches the
critical 500 - 550 C range where molten aluminum starts to flow. The sequence of
events observed in WTC 2 is repeated in WTC 1 and a second global collapse ensues.
There was no steel foundry at ground zero, and remember this:
Edited by skyeagle409, 20 March 2013 - 06:33 AM.