Wednesday, August 31, 2016

Process Wednesday: reactions with galvanized drums

I have been remiss in not tracking Scientific Update's process chemistry blog over the last couple of months. They have been posting with some regularity and adding some content from recent presentations at conferences that they run. Here's a nice bit of safety-related information written up by Will Watson: 
At the recent 'Scale Up of Chemical Processes Conference' in Baveno, Italy, Wim Dermaut from Agfa presented some case studies where problems have occurred as a result of reactive chemicals present in waste streams. In the first case study a drum containing a waste stream including diethylhydroxylamine exploded. The most likely cause was caustic present in the empty drum which initially raised the temperature of the waste to a temperature that interaction with Zn led to the runaway reaction (the waste drum was galvanized). 
Interestingly the supplier of diethylhydroxylamine maintained that it was safe as they only saw an endotherm in the DSC, whereas Agfa’s own studies showed an event with an onset at 105°C with a very rapid decomposition. The key difference was that the supplier had carried out their DSC run with an open cell. 
This is the first time that I've heard of a galvanized drum causing a runaway reaction, but I have heard of cases where zinc contamination comes from a galvanized drum. 

1 comment:

  1. Reminds me a mishap my colleagues had at a CRO - polymer was precipitated from reaction mixture which contained a large excess of hydroxylamine and also some lithium hydroxide. The precipitation required gradual addition and a long stirring time. Since the precipitation solvent was fairly innocuous - alcohol based - a cost-saving "innovation" was to use new clean galvanized steel drums as a disposable precipitation vessel. Those drums in the first run ended up heavily corroded - a really bad thing since the polymer contained metal coordinating hydroxamic acid moieties... The next run was precipitated in a glass vessel.


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