1. Mick West

    Mick West Administrator Staff Member

    [​IMG]

    After reading how most of the insulation in the world trade center was "Slag Wool" (a type of mineral wool insulation made from iron refining) I wondered if it might have some iron microspheres in it. So a little searching led me to the above image, from:
    https://inspectapedia.com/insulation/Rock-wool-microscope-identification.php

    They are very interesting because they look like iron microspheres. But without checking with a magnet, it's impossible to tell. They might possibly be melted fibers with some carbon making them dark.

    Another possibility is lead. Some slag wool was made from lead slag - although it's not clear when that practice stopped. Seems to have still being going on the 1970s though
    http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.836.5918&rep=rep1&type=pdf
    Metabunk 2018-10-16 12-16-32.

    The "Fowler 1980" reference leads to:
    https://www.cdc.gov/niosh/docs/80-135/NIOSH_Pub_80-135.pdf?id=10.26616/NIOSHPUB80135

    Which describes how the process creates spheres ("shot") which is separated from the wool
    Metabunk 2018-10-16 12-28-50.

    The shot here is slag though, not iron.
     
    Last edited: Oct 16, 2018
    • Informative Informative x 1
  2. Mick West

    Mick West Administrator Staff Member

    More on lead in slag wool:
    https://www.osha.gov/dts/osta/otm/otm_v/otm_v_3.html
    Construction of the World Trade Center towers was in 1968 to 1970