In general, coal used for heating, although it will burn hotter, is not really suitable for forging because 1. It "pops" as it burns, sending hot shards, embers, and hot sparks flying around wildly. 2. Heating type coal does not "stick" together or "clump" like softer coal, meaning that it won't form the traditional "beehive" fire that most blacksmiths use. "Good" blacksmithing coal can be difficult to find, the soft variety is preferred for building/maintaining the fire, but you also want a very "clean" coal, that is low in sulfur and other impurities that steel can absorb during heating. With the types of steel used in Blademsithing, coal that is high in impurities can literally "break down" the steel, in some cases I've seen this so badly that a bar of flat stock was turned into what looks like a pile of black cottage cheese on the anvil.
For a few years I made and used my own charcoal for forging......when I lived in the south, hardwood pallets were free for the taking. I'd cut them in thirds with a chainsaw, put the thirds in a 55 gal steel drum and light them on fire. Once they material was about 2/3 burned, I would turn the barrel over, shovel dirt all around the edges, and leave it overnight. Next morning I'd dump it out on a sheet of plywood, go over it with a magnet to get all the nails out, and I'd have about a days supply of forge fuel. (About 3 full pallets is what it would take to produce a day's worth of fuel) Charcoal is really nice to use in a forge (NOT THE CHARCOAL BRIQUETTES YOU BUY AT THE STORE). It provides a high, very clean heat. The drawback is that you have to constantly feed the fire, as it doesn't last long.