okay - to start with the obvious (bearing in mind I am not an expert in this but there is read across to other industries...)

The water and coal dust mix would be a contaminent so you would need some sort of containment/seperator.

The dust, once all the coal is removed, is flammable so think about DSEAR and have appropriate mitigation measures in place (including for any tools used [think of the old ATEX system and you can't go far wrong with a bit of tweaking])

It should be classed as a confined space.

Breathable air? Rescue options & gas monitoring.

I would suggest looking at other industries for cleaning in case there is a better method (brewing - their grain silos etc).

On the other hand, being a solid (even fine) why would the inside need cleaning? I assume it would remain dry and therefore the dust should come out by itself (how about trying a new system out - sonic shocking the silo to 'knock' the dust out? just a suggestion, remember, I am not an expert!!!)

I am sure there are personnel better qualified than I to give you a better idea.

You could contact the HSE directly for any suggestions?

Good luck and let us know how it turns out.

Hi,

Not sure what you mean by "fine coal"; is that the size/grade of the coal or the quality of the coal? Might make a difference.

As for cleaning the silo, I am working on the idea that these silo's are around the size of a closed rail truck, possibly stood on it's end? I would not go for the power wash, why create a coal slurry that then needs further processing? I would suggest looking at the possibilty of fitting rapping gear on the outside of the silo to shake the coal down, especially if you get problems such as the coal not flowing due to excessive dampness when being delivered.

Jim