Explosion in an academic laboratory

The explosion happend in a chemical workshop, when treating sodium metal rest before disposal. The process produced hydrogen, which in this case ignited and exploded.

The chemistry department of he university routinely dried solvents using metallic sodium. The excess of sodium metal was treated as waste. This was done by oxidising it by a reaction with a solution of isopropyl alcohol (IPA), to create an inert substance before disposing it.
The by-products of this reaction are hydrogen gas and heat.
The operation was performed by a PhD student, who had already executed it before. He left the reaction for approximately four hours in the fume cupboard. Upon return, he added more IPA to complete reaction. The production of hydrogen and heat accelerated. The hydrogen ignited and exploded, and the solvent ignited and ejected out of fume cupboard onto him.
He was lightly injured.

The INITIATING CAUSE was an excessive production of gaseous hydrogen during a reduction reaction.
The reaction between metallic sodium and a alcohol oxidises sodium and produces gaseous hydrogen. it is a exothermic reaction and therefore produces also heat. The quantities used are unknown, as well as the temperature reached by the reaction. Also the source of the ignition is unknown, but it is clear that the quantity of hydrogen produced was enough to produce an explosion.
The ROOT CAUSE was probably the lack of a correct risk assessment. According to the HSE report, the department had performed a risk assessment for individual substances but not for the reaction. This lack of safety knowledge was probably reflected in a lack of correct instructions, which left to operator's own judgement the execution of the process.

Process to oxidise metallic sodium metal. fume cupboard.

The chemical reaction operation was performed in a fume cupboard. The reason of the ignition is unknown, as well as the temperature reached by the reaction.

DESCRIPTION OF THE DISPOSAL PROCESS
The residual metallic sodium (Na) was oxidised by reacting it with an alcohol, to produce sodium hydroxide (NaOH).
In the case of the accident, a solution of isopropyl alcohol (C3H8O) was used, in solution in toluene (C7H8) which is chemically inert. The reaction produces gaseous hydrogen.

The PhD student burnt right hand & right side of face, which healed quickly.

The university department planned to buy anhydrous solvents, to reduce excess sodium metal production. They investigated as well safer methods to destroy metallic sodium.