Personally, I wouldn't use anything with relatively high (>0.5%) silica content for blasting unless I had negative pressure facilities (to prevent contamination of adjoining land/people) and a hugely filtered and efficient pressure fed respiration system. Real crystalline silica has been commercially illegal to use for blast cleaning purposes in the UK since 1950 for a pretty good reason.......
With the huge array of "safe(er)" media available these days, I don't see the point in risking it at all anyway.
For one, crushed glass works well. It's available in different grades and is good for lower pressures (60-80psi) than glass beads because it's sharper - although you still need a decent flow behind it. It's also better than bead if you have a venturi pickup type blast system again due to the shape. Last time I bought some I paid around £10 for ~50kg (from a commercial blast company rather than a media supplier - they sold it to me at the per tonne price rather than the bag price).
Of course, if you really do want to use sand then have at it - you're far enough away from me that it won't affect me directly :neener:
