Actually, Peter Tully of Tully Construction told Christopher Bollyn in the summer of 2002 that he had seen pools of "literally molten steel". Mark Loizeaux confirmed Tully's reports, and reported that there was molten steel at WTC7.
Further, in September 2001, Robert Leifer of DOE in New York, contacted Thomas Cahill of the DELTA Group at University of California. By October they had placed a device known as a 8 stage rotating drum impactor to collect air samples. It was placed at the edge of the "exclusion zone" monitoring the air. While they were monitoring the air, the EPA was doing nothing except telling everybody everything was fine.
The air samples show large presence of iron rich and silicate spheres.
Thus, your claim that molten metal (iron) was not present is wrong. It is mere regurgitation of the official story.
How can anyone, even a construction professional, tell if a molten metal is steel or something else? The only way is to wait for it to cool and examine it, though measuring the temperature will rule out some possibilities. However, none of the accounts I've seen include this verification, it is all just based on eyeing pools of molten metal.
Microspheres are another matter. They are metal that has been briefly molten, but cooled rapidly due to their small size giving a high surface to volume ratio. They are nothing unusual, and are found wherever metal is worked since the energy of the working can be concentrated into small volumes to raise the temperature to melting point. Welding fume and the sparks from an angle-grinder are common examples. At WTC they would have been produced in the construction of the buildings, subsequent maintenance, in the violent grinding together of building components during the collapse and in the clear-up.