Dear Jonty,
I have great admiration for the technicians who have to connect those sequences of 100's of holes up - and the smaller complicated ones as well. To see those lines going off in perfect sequence will be very satisfying to those put them all together! - and relief when those really big rounds were initiated (a few hidden fingers were crossed somewhere!). I was not involved with such large scale work, and have anyway been out of things for fifteen years or so: so, whilst the principals are known, I was overtaken by technology long ago! - things progress ever rapidly now as well obviously.
Coal dust explosions need a significant amount of suspended dust to occur, and invariably need flame to trigger them. It is long established that gas explosions in collieries triggered dust explosions (sometimes these secondary explosions were worse than the initiator): the gas explosion blast picking up dust and the fire of the gas obviously setting off the dust... once taken the whole lot would 'roll along' -very very unpleasant. It didn't take long for the mining technologists to work out solutions: the spreading/laying of limestone dust in underground roadways being the first main solution. However, the best solution was/is to get to the dust at the point of creation, hence water sprays/misters effectively did away with this particular problem.
As to a ship suffering from a coal bunker dust explosion... not impossible, but the conditions and sequence of events would have to be 'perfect'. That fireball on the Link was, as obvious, due to a huge amount of dust being thrown into the air at once, which, being 'chased' by the fire of the explosives could/would only do one thing! Impressive all the same, and entertaining(!), but not quite 'good practice'!
Regards, Bernard