[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: sand reuse

I can't believe that the research I did on this topic in graduate school
will actually serve a practical purpose!! The research I was involved in was
actually on reuse of spent foundry sand, but it's the same answer.    No.  

Although it's possible to use spent sand in any of these applications and
many researchers have actually done it in a lab, you'll virtually never find
it done in practice because it's not cost effective.  Virgin sand is dirt
cheap (cheaper actually).  The main cost is transportation.  The industries
you've listed are very cost-driven.  Most firms in these industries are
located close to their sand source for this reason.  Even for industries
that don't have a nearby sand supplier, maintaining a consistent, precise
grain size is crucial.  Consistency is very hard to achieve for a waste
product, especially from a sand blasting where the surface being blasted is
never the same.  

At first blush, it might seem like asphalt pavement or concrete might be
potential markets where spent sand could be used for less than the cost of
landfilling it, but a detailed study of these products will reveal how
important it is to maintain consistency to meet Federal Highway
Administration specifications.  There are other problems with these markets
too.  If you're interested I can fax you the 3-page article we published
about this.

The best potential uses I can think of for blast sand (which aren't too
promising) are:
*	Landfill daily cover
*	Flowable fill
*	Asphalt pavement for parking lots

Flowable fill is like low-strength concrete. It's used for filling trenches
and such.  This is probably the most promising application for blast sand,
but the grain size may be too large.  The parking lot market also has some
potential because FHA specs and strength requirements are less critical than
for roads.  I can put you in touch with foundries who do this with their
sand.  But asphalt batchers want a steady, large volume supply.  Your volume
isn't worth their bother.  Your storage and shipping costs would exceed the
cost of disposal.  

The P2 moral is that reduction at the source is far more economically viable
than waste reuse.

Mike Heaney
NC Division of Pollution Prevention &
Environmental Assistance