Small explosion in a chemicals manufacturing plant

In a plant producing calcium carbide (CaO + 3C -> CaC2 + CO), a dust collector clogged, probably due to the failure of the cleaning device (nitrogen nozzles) which allowed the dust to build a plug.
During the procedure of introducing a poker through an inspection hatch at the lower level, a small explosion occurs and a large amount of dust is ejected through the vent. The cloud containing carbon monoxide and hydrogen ignited.

The fire spread to the electrical cables supplying the equipment.

The INITIATING cause is the manual intervention executed to free the dust collector.

The intervention was inadequate, because executed at the wrong position (under the clogged zone) without the knowledge of the hazards involved (opening of a hatch and mixing hot reactive powders with air).
Therefore the root cause is probably related to lack of adequate procedures and/or adequate operative and safety training

calcium carbide reactor and its components

The dust remover of the reactor had clogged and its cleaning required a manual intervention.

According to source, a worker was only slightly injured by incandescent dust jets. The furnace was shut down for 25 hours and the dust collector for 15 days, during which 87 t of dust (lime) was released into the environment.
Residents were inconvenienced and traffic on the nearby highway disrupted.

The source does not report improvement requirements. Nevertheless, the inadequate manual de-clogging intervention shows that better procedure and better safety training are needed.