I found this. Apparently it was called Nitriprill HD.
“The Nitroprill HD indicating high density is probably physically robust porous prill with a built-in resistance to breakdown due to temperature cycling and abrasion as indicated by western experts”
speculation is that Nitroprill HD is a knockoff of Orica’s Nitropril:
http://www.oricaminingservices.com/au/en/product/products_and_services/bulk_systems/nitropril/56
the technical data sheet for Nirtropril states:
Safety Features
Nitropril™ is a strong oxidizing substance, which will react with organic materials, reducing agents and metal powders. Whilst not combustible on its own, Nitropril™ supports combustion and increases the intensity of a fire.
Nitropril™ is not readily detonated in unconfined conditions, but will react with materials such as strong reducing agents and metal powders.
When heated to decomposition, Nitropril™ produces nitrous
oxide and white ammonium nitrate mist and or brown fumes.
Brown fumes indicate the presence of toxic oxides of nitrogen”
http://www.oricaminingservices.com/download/file_id_21273/