Treatment of nitrocellulose by thermal decomposition

Waste fines generated during the manufacture of nitrocellulose (NC) are classified as a RCRA K044 hazardous waste due to their explosive properties. The objective of this study was to evaluate controlled thermal treatment of NC in order to render it nonhazardous and allow for more economical ultimate disposal. The results indicate that controlled thermal decomposition at 130-150 degrees C is a technically feasible process. Rates improved significantly at higher temperatures. At 150 degrees C, only 10 hours were needed to reduce the nitrogen content of NC from 13.7% to below 10% (versus 105 h at 130 degrees C), a revel found in many commercial, nonhazardous grades of NC. The air flow rats over the heated NC, and the moisture content of the NC or air above it had no discernible effect on rates of nitrogen removal. Greater mass loss from the NC than what was attributable to the nitro groups alone indicated that decomposition of the poll;mer backbone also occurred. This was confirmed by FTIR analyses, the appearance of CO2 in the off-gas, and a lack of correlation between percent nitrogen and heat of combustion Samples of thermally treated NC containing 9.7% nitrogen failed three of the basic tests used by the Bureau of Explosives to ascertain explosive characteristics, indicating that the product was no longer hazardous based on its energetic properties. Although technically feasible, use of thermal decomposition to treat NC fines will most likely be restricted by safety concerns. Operating close to 130 degrees C would mitigate the risk, but considerably extends the time required for treatment. The most suitable application of this technology may instead he treatment of NC-contaminated soils.