First, barium nitrate is both a health hazard and an oxidizer.
Get an MSDS at Fisher Scientific:
It gives the hazards and other properties, but has typical boilerplate language re disposal:
“Chemical waste generators must determine whether a discarded chemical is classified as a hazardous waste. US EPA guidelines for the classification determination are listed in 40 CFR Parts 261.3. Additionally, waste generators must consult state and local hazardous waste regulations to ensure complete and accurate classification.”
Two reasonable alternatives before resorting to a haz. waste disposal company($$$):
1) Find someone with a use for it. It's not a waste if it has a use. E.g., give or sell it to someone trying to reduce sulfate concentration in effluent (barium sulfate has an extremely low solubility), e.g.,
Sulfate removal thread164-47948
Decreasing high Sulfate (SO4) and chromium level thread161-50054
How to eliminate Sulfates from waste water effluents thread127-37319
A small quantity, say a 500g bottle, can be shipped as a ‘Sample.’ Seal the bottle in a plastic bag, then pack it in vermiculite inside a metal can (buy an empty 1 gallon paint pail & lid). For larger quantities, check DOT shipping regs.
2) Convert it to something non-hazardous, i.e., barium sulfate (which seems to be only hazardous as a dust; get the MSDS from Fisher Sci.): Dissolve in water, add slightly more than the stoichiometric amount of sulfuric acid, then neutralize with caustic and let settle. Pretty easy if your company already neutralizes acids. The water goes down the drain (get permission from your POTW for a little sodium nitrate), the solids go into the wastebasket or include with any hazardous waste your company already disposes of. This presumes a small,
de minimus quantity (no treatment permit required).