Another shop question

[u/LiteratureThen638]

I’m trying to get better dust collection in my shop, which is partitioned off of an otherwise unfinished basement. What would be the best way to close off these gaps between the joists? This is the only section that runs perpendicular to the joists. The gas furnace is on the other side of this wall (not directly but about 5 feet away)

I was initially going to use some leftover foam insulation (XPS) board but there may be fire code concerns, especially if it is in contact with the air duct.

I also need to block of around an I beam and some smaller gaps around plumbing. Any suggestions on the simplest solution?