In an organic chemical industry, an explosion occurred during the distillation of 1-nitro-anthraquinone, causing the rupture of the melting vessel. The explosion was followed by a fire (1-nitro-anthraquinone and nitric acid contained in the vessel and hot-oil used in the distillation process) which caused nitrogen dioxide to be released into the environment. The plant was shut-down and evacuated. Roads in the area were closed by the police.
The plant was completely destroyed by the fire. The cost of the damages has been estimated in about 50 millions of German Marks (about 24.4 M ECU). One employee was killed and 5 were burned.
The cause of the explosion was the spontaneous decomposition of raw 1-nitro-anthraquinone initiated by the catalytic effects of impurities (inorganic salts). The decomposition was unexpected because of an insufficient process analysis. After the accident, the plant had been thoroughly investigated and it was established to extend tests on the thermochemical reactions carried out.