I'm sorry for my english.

I suggest two things about burning coal that will have to be an ecological horror.
The first is that burning coal releases sulfur-containing compounds into the air, which causes acid rain, which could be involved in extensive aerial pollution, which is more durable and dangerous for plants.
The second: burning also generates a large amount of ash, which can be similar to the waste created by the bloomery that must be stored in view of why not use later.