We all know that some forms of coal don't work well for blacksmithing. But does anybody out there have some testing of "non-blacksmith coal" that they'd care to share. Don't be shy. I don't think anybody will flame you for trying some "mystery coal" and then ratting on yourself.
Blacksmiths must use more than one kind of coal. For instance: When we were in France at a blacksmith conference at Arles-sur-tech some years ago, they were burning coal that had more volatiles than I have ever seen before or since. The smoke from it would go a couple of feet into the air and then actually ignite again!!!
I might even have a picture or two of the flames.
I got some coal at a blacksmith auction once. It looked like the old stoker coal that our neighbors used back in the 1940's. Dull gray, it was and no pieces were larger than about 1/2" cubed. It would NOT coke up at all. It did not get very hot in the forge. Don't remember ash content or smell (sulphur).
Don't tell anybody I told you this, but I gave up and buried it (about50 pounds). Ashes to ashes, dust to dust, coal back where it came from, says I. Wait till the archeologists find THAT some day!
I was browsing through my 1973 copy of "Marks Handbook for Mechanical Engineers" a few years ago and found 55 pages in it about coal. Very enlightening.