which sander

Ayuh,.... A floor sander, 'n a coarse belt,....

If sanding, even with one with a dust collector, you'll need the bath window open with a strong fan in the window blowing outward, the door open plus a good respirator.

+1

Those particle fibers and resins aren't good for you.

Might be easier to just pull up the subfloor and re lay it.

What's the plan for the finished floor?
How thick is that subfloor?
Your going to spend far more time and money on a sander, all the belts needed, floor leveler and end up with a weaker floor by trying to reuse what there now.

The only way to salvage that floor "IMHO" is to take it out and replace.You will spend more time dealing with it and end up with a crap subfloor after all of your work.

handymom34 said:

(replacing the plywood is not an option

Click to expand...

Why? That would be my first option.

Try placing a soaking paper towel over a spot, see how much the particles soften. Soak the towel every few hours, keep the spot wet and try scraping after about 1/2 a day. If the glue/particles can be scraped away to relatively flat (1/8" of the stuff left over? - I'd call that success), you can trowel thinset and cover with cement board. Same operation with paint thinner or such. If nothing works, scrape as much as possible, seal with primer or redguard, thinset and cement board. Predrill and countersink the board and you can adjust the board - edges meeting, etc. Blunt screw will bring the board up. Too much adjusting will break or weaken thinset. Dry fit the boards first.
I never tried, but I'm guessing particle board may soften first. Plywood is more resistant to damage so don't worry about it.

I would also replace the subfloor--however, your question is "what sander will remove this?"

Answer--a 4 1/2" angle grinder --set up with 60 grit paper disks (2-mounted back to back) will clean off that mess in a dust filled hour.