You've got the black point set up too high, just like pushing shadows from a raw-file, you'll end up with noise.
Here's some screenshots of what I do, different equipment probably, but this illustrates what I do using my Epson v750 on ImageScan! for Linux under GIMP with the epkowa driver (ymmv).
Set the gamma to max (5, lowest contrast), White point to min (brightest), set the blackpoint to the lowest where it looks 'black' enough, but doesn't muddy everything else:
Set the gamma to min (0, highest contrast), set the whitepoint to just above where it clips highlights:
Then set the gamma until it looks good:
Once it's scanned, check the curves and do a final tweak:
You can see here that the white-point was maybe set a bit high when scanning, so i've pushed the whites up a bit in the curves. If i was particular about this shot, i'd go back and re-scan with the whitepoint down a bit to get more info and stretch the info a bit more.
Here's a 100% crop at 1600dpi, absolutely no noise in the black (in the shadows or film border):
(I only scan 120 film at 1600dpi initially, keeps the filesize down to 10MP or so. Once i've decided what's "good" I'll do a proper wet-mount scan at 3200dpi for a 40MP file, sharpen and whatnot on that one).
OK, so no points for artistic merit, first on the roll to check the light-reading. Also, I have 'Unsharp mask' in the scanning software turned definitively OFF. I'll sharpen my own stuff using this method
(or a similar variant). auto-software sharpening increases grain and noise, and dust-redustion and everything fancy is also off.