‘The Oppau explosion occurred on September 21, 1921 when a tower silo storing 4,500 tonnes of a mixture of ammonium sulfate and ammonium nitrate fertilizer exploded at a BASF plant in Oppau, now part of Ludwigshafen, Germany, killing 500–600 people and injuring about 2,000 more.
The plant began producing ammonium sulfate in 1911, but during World War I when Germany was unable to obtain the necessary sulfur, it began to produce ammonium nitrate as well. Ammonia could be produced without overseas resources, using the Haber process.
Compared to ammonium sulfate, ammonium nitrate is strongly hygroscopic, so the mixture of ammonium sulfate and nitrate clogged together under the pressure of its own weight, turning it into a plaster-like substance in the 20 m high silo. The workers needed to use pickaxes to get it out, a problematic situation because they could not enter the silo and risk being buried in collapsing fertilizer.
To ease their work, small charges of dynamite were used to loosen the mixture. [..]’
December 8th, 2009 at 10:52 pm
A small charge of dynamite was used to break up the ammonium nitrate / ammonium sulphate combination “30,000 times” previously without incident. Ammonium sulphate is added to ammonium nitrate specifically to keep it from exploding. 50% is necessary, 60% was used. So why did it explode this time?
Also, if the explosion was caused by ammonium nitrate, then why an explosion (detected 85 miles away) followed by a second, larger explosion 22-seconds later? … and why did a “tremble” precede the first explosion? … and why did Fritz Haber, who was 35 miles away at the time, describe the explosion as an “earthquake”? And if ammonium nitrate was used as an explosive during WWI, why did Haber describe the incident as a “new, powerful force.”
These are rhetorical questions, but I’ll attempt to answer them in my book, The Flight of the Hog Wild (see link).