Re charcoal: North of me (Katahdin Ironworks) there is an old ironworks. Iron ore was mined and smelted into pig iron billets. The smelting was done with charcoal. The charcoal was made in large bee hive ovens with a vented top (stone etc), A smoldering fire was lit in the hardwood stacked inside and allowed to burn until it went out- several days. The result was charcoal that could burn hot enough to melt the iron out of the ore. This continued I think until the 1920's.
"Eric Sloane wrote about the importance of the charcoal makers to America's early history."
He did and made excellent drawings of old wrought iron tools. The colonial blacksmiths hand forged these tools, hammering them out on the anvil. Plows, carriage axles, pitch forks, hinges, kitchen utensils, etc. were all made using by blacksmiths using charcoal (home made) for fuel, with a bellows, forge, and anvil. As America became industrialized, soft bituminous coal (not the hard anthracite used for heat) was mined and replaced charcoal- efficient. I used to buy Pocahontas Pea coal, and Soule soft coal from West Virginia for forging. Great for forge welding. I've tried charcoal- works fine as well. (When the coals are glowing in the woodstove- that's the heat you want for forgework.)
The charcoal/soft coal imparts carbon to the wrought iron - giving rise to carbon steel and fancy damascus steel blades.
Charcoal is great stuff - but I prefer mine in the form of charred toast edges - gives it a certain taste- and if it is too charred- I just tell myself it's healthy!
Coke- is what you get when you use the same type of process in burning wood, but with coal. The impurities burn off and the coal cokes up. It is this coke that burns hot when you forge. As it is coking- there is a stickiness to the coal. This happens quickly with soft coal. It used to be that you could buy 2"-3" chunks of coke 1950's, 1960's made from anthracite by the ton. -Not so good for forging (really need a super blower), but fine for industrial types of use (smelting/drop forging).
Beehive kiln to make charcoal below - the smelter is to the left in distance (packed with charcoal and ore- melted iron ran out below.)