At around 6:45 p.m., security guards noticed smoke and flames coming from the white phosphorus storage area of a fireworks factory. A drum had been dripping white phosphorus. When exposed to the surrounding air, the phosphorus reacted with the oxygen, igniting and emitting white smoke. As there were not enough employees at that time of day to deal with situation, the firefighters were called in. The drum, which was leaking from its bottom, was placed into a water-filled bund to immerse the leakage points.

It was a so-called ‘empty’ drum in that it contained 1–2 cm of phosphorus topped by a safety layer of water. The drum was slated to be shipped to an outside contractor for treatment. An inspection of the drum revealed a series of corrosion points at the surface of the phosphorus, i.e. 2 cm from the drum’s bottom. This series may be linked to a reaction between air and the phosphorus that produced phosphoric acid that attacked the drum’s inner lining. Either the drum had not been filled with enough water or heat had caused the water initially present to evaporate.

This was the first time that drums were to be shipped off site for treatment. Until then, they had always been treated on site without the need for storage. This extended storage phase had not been identified as a new risk factor and the operator had not changed the instructions about the level of water to be maintained in the drum. There was a lack of communication between the workshop employees and the shipment preparation employees on the depth of water required during prolonged storage of the drums.

Although the establishment of better storage conditions for ‘empty’ drums would have allowed the external drum treatment trial to continue, the operator decided to opt for burning the contents of the bottoms of the drums on site. Technicians were asked to be extra vigilant when treating drums belonging to same batch as the one that ignited.

The operator specified that a 10-cm layer of water was to be maintained in the drums at all times prior to their disposal.