The Reading T hogs with Wootten fireboxes mentioned as culm burners had Tuyere grates rather than fingerhole or interlocking finger style which probably accounted for their ability to maintain a firebed made up of smaller particles of coal. I remember back in the 1960s seeing grates like this in one stored locomotive at the NH&I, not sure if they were used a lot but might allow somebody using them to make use of this resource.

Someone should apply for a $1B government grant to demonstrate “carbon capture” technology, buy the pile of coal, move it to an abandoned lot, and say “tah-dah! 400 tons of captured carbon!”