A thick cloud was observed for 45 min near a plant producing titanium dioxide. The gases stemming from the attack on ores (slag) by sulphuric acid were normally treated in a processing and regeneration unit. This attack and the gas suctioning had stopped subsequent to an electrical outage; 600 kg of sulphur dioxide/trioxide and H2SO4 were released into the atmosphere by a valve in order to avoid a pressure surge in the reactor, with the exothermic reaction continuing at a slow rate until the attack on the ore load came to an end. A similar incident had occurred 2 months prior following controller malfunction. Children at a nearby school complained of breathing difficulties. The unit’s safety report was completed (electricity supply cut-off, transmission and water supply circuits). An efficient detection apparatus, even in the event of electrical outage, and emergency response resources (electric generating sets, washers, etc.) were to be proposed.

Download the detailed report in .pdf format (71 Kb)