Coal Mill Pulverized Coal 200 Mesh

I presume this was pulverised coal rather than clinker from a coal mill? It is possible that the coal has become easier to grind. Has the source of coal been changed? It is possible that the sieve being used has developed a hole. Has the sieve been changed? If the % passing has indeed increased then the feed rate to the mill could be increased to grind the product more coarsely.

Coal