I don't suppose it would throw the number too much, but does it depend on how fine the salt is? I would suppose that the more coarse the material, it would weigh less per yard since there would be more air space by volume. Kind of like buying stone. Or are we just best off assuming about 2200 lbs per yard?
It is typical to assume rock salt weighs about a ton a yard. This doesn't account for the moisture content, or the size of the granules. Especially in bulk, you get a variety of granule sizes from dust to...?
The figures below are according to my Pocket Ref
I know this just confuses things even more........
One addition thing to add is water content. Sometimes our salt is bone dry sometimes the train can pull up with water almost running out of the back end. Our semi driver said it can be as heavy as 2600# per yard. it suck when you have to pay for water weight!