I haven't ever heard that the Glass beads are worse than Silica sand, but would be skeptical since glass contains Silica. I have never heard of "Black Beauty", but after a quick Google, it sounds as good as anything else.
It will depend on what your blasting and what type of finish you want, of course the finer the blast media, the smother the surface. I see Black Beauty has a medium to elite grade, so a nice range.
I copied and pasted from here
Black Beauty® Abrasive (Boiler slag, Coal slag) from READE
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Black Beautyï½® Abrasive Normal Chemical Composition:
Silicon Dioxide = 41-53%, Silicon Dioxide- Crystalline "Free Silica" Quartz= <0.1%, Aluminum oxide= 17-25%, Titanium dioxide= 0-2%, Iron Oxide (FeO)= 7-31%, Calcium oxide= 3-15%, Magnesium Oxide= 0-4%, Potassium Oxide= 0-3% and Sodium Oxide= 0.62%. Source= Harsco Minerals MSDS
If you have a hood, use a cross wind so it doesn't cavitate against your body and use your mask, i think you'll be fine for what your doing.
