KW you are correct, Anthracite is about 92% pure carbon and does not give off tarry or other hydrocarbon vapours when heated below their point of ignition.
When I lived near Buffalo, NY the steel plants would bring in Bituminous Coal and run it through a high temperature oven to remove any impurities. The resulting prodict was coke, a highly effective fuel, essentially producing double the heat content of the coal.
The coke was then used to melt the ore and other ingredients to make ingots of pig iron for later smelting.
The smelting furnaces had little or no smoke as they burned the coke, but the ovens used to make coke would release a reddish brown ash that covered everything in about a half mile radius.
It was a dirty job.
Humphrey's DownEast Beast W/BBQ Guru