Explosion in a chromium ore mine

A natural hydrogen release caused a fire at a chromium ore mine, forcing a temporary suspension of operations at the facility.
Three workers were injured.
Hydrogen emissions had already occurred in the past.

The INITIATING CAUSE was the creation of an explosive air-hydrogen mixture in the mine.
It is well known that hydrogen may be present in mining activities in ophiolites geological formation. Although the source of this event description does not provide a ROOT CAUSE, considering that hydrogen-air explosions had already happened in the recent past, it can be assumed that a lack of proper risk assessment and related safety provisions was at the base of the explosion.

EXPLANATION OF THE GEOLOGICAL PROCESS
Hydrogen is emitted from chrome ore (chromite) mines because of a natural geological process called serpentinization, where iron-rich rocks react with water under high pressure and temperature to create hydrogen gas.
This is a common phenomenon in the ophiolite formations where chromite is mined. Mining operations can puncture a trapped underground reservoir, causing the release of this gas.

Two workers suffered burns to their faces and hands. All three ended up hospitalized, with two in intensive care in serious condition, and the third in moderate condition in the trauma department.

The government suspended all mining activity waiting for experts to investigate hydrogen emissions and other associated gases and assess their impact on workplace safety. Moreover, local police launched a pre-trial investigation under a provision of the criminal code related to violations of safety regulations in mining or construction work that result in serious or moderate harm.

Explosions in mining are well-known phenomena. However, the most documented and assed ones are related to methane-air explosions, because methane is the most encountered combustible gas in underground atmosphere. Therefore, it is also the most dangerous hazard in underground mining minerals such as coal, trona, potash, limestone, oil shale and salt. Additional gases can also be found, depending of the type of mines, such as hydrogen, carbon dioxide, nitrogen, oxygen, etc..
[Cheng et al., Methods to determine the mine gas explosibility – An overview, J. Loss Prevention in the Process Industries, 25 (2012) 425-435, https://doi.org/10.1016/j.jlp.2011.12.001]

Methods for the prevention of methane explosions have been developed since several decades of experience.
This incident is peculiar, because of the very high concentration of hydrogen, uncommon to type of mining atmosphere, and for which perhaps the available knowledge and risk management methods are not well fitted Indeed, hydrogen properties make mine explosions more rapid and powerful than the menthane ones. The consequences are then higher pressures and shockwaves with higher risks for workers.
[Skob et al., Numerical assessment of hydrogen explosion consequences in a mine tunnel - ScienceDirect, IJHE 46 (2021) https://doi.org/10.1016/j.ijhydene.2020.09.067]

Moreover, possibly due to geological peculiarities of hydrogen reservoirs, their punctuation of can cause a much quicker diffusion of gas and formation of explosive atmosphere than methane.

Anyhow, hydrogen presence in chromium ores mining is a now a known phenomenon, and an effort is required to develop realistic accidental scenario serving correct risk assessments and effective safety design.