transforming Coal into Coke

[ahdlm]

alright. been a member here for quite some time, but this is my first post.
i've been reading up on forges and smithing for a while in preparation of giving it a try to make some rather simple tools that just cost too much to buy new.

In my "research" i've read that at the heart of a coal forge is a coke fire, that is surrounded by coal that is turning into coke. This is the process that im interested in learning about. how long does it take to transform coal into coke?
I have seen both coal and coke from a farrier supply near here, so I think I know the difference in appearance. Is the process simply managed on appearance or are there other factors that determine when the coal is indeed transformed into coke?

In the interests of simplicity, could I not just buy coke and use it directly? it costs 50% more than the coal, but then I'm not going to be doing alot of forging compared to most folks in here.

[fat pete]

some use just coke...but now i find out about breeze....i am familiar wiht the coke you referr to...and the proces starts as the coal burnsin a shrt time you notice the coal starts to stop being shinny and starts to kinda grow and deform then gets kinda crusty ...thats coke, easier to light and burns like a coleman mantle....if you would only use coke i believe it would burn up pretty quick, much quicker than the coal....breeze is some kind of baked soot from petrolium plants is what i am told...it looks like a stone that was heated alot....burns kinda like coal but needs air more than coal.. it is also harder to light, but seems to burn just fine, maybe a little cleaner than coal...some guys do just buy coke, i would rather burn coal and work with the coke...seems if i just used coke i think it would burn way quicker and i would loose the time as i was burning coal plus the time with the coke....seems guys who cant get coal buy the petro coke... now a litle history Andrew Frick used to make coke for carnegies furnaces ....he became a millionair doing this and the process was akin to making charcoal with hardwood....thats all i know....

[MattBower]

You're overcomplicating it. The amount of smoke your fire is producing pretty much tells you all you need to know. Build a coal fire. When it gets to the point that it's only giving off a little smoke around the edges, it's a coke fire -- the smoking area around the edges is where you still have come unconverted coal. As you run low on coke in the fire, you periodically rake some fresh coke from the mound around the edges. And as the mound gets low, you periodically refresh it with new coal, which converts to coke while you're working. This is all much simpler to do than to explain.

[Rob Browne]

When you are running a coal fire once you get it started you keep it surrounded by wet, green coal. This coal heats and gives off the volatiles, expands and becomes very light compared to the original coal, this is breeze (commonly called coke). You are actually buring the breeze in your forge fire which is effectively a charcoal fire. You constantly make more breeze by slowly pushing the green coal in to the fire so more is being converted to breeze as you work. This stops the panic when you run out of breeze and are forced to pile on green coal which produces great clouds of heavy, smelly smoke. Good fire control ensures a virtually smoke free fire with a constantly refreshing supply of breeze.

Breeze is very easy to light and gives off very little smoke so you always keep the breeze from your last fire to get the next one going. Also, a coal fire will keep burning while the air is turned off, a great characteristic if you are using a small bellows or hand cranker.

Now, real coke is made from coal that is baked to force off the volatiles so these gases can be used in industry. The left over is a hard sort of glassy rock which is hard to light and needs a constant air supply (an electric blower is essential or a blower slave). After saying the bad bits it is virtually smoke free as the voaltiles are not there to form the smoke and you don't have to worry about making more, its already there.

Pick your poison :)

[ThomasPowers]

Industrial coke burns way slower than coal does. It's hard to light--often an O-A torch is used. It goes out unless you have constant airflow--- electric blower rather than bellows or hand crank blower suggested. And can get WAY HOT coke firepots are usually much heavier duty than coal firepots!

[ahdlm]

Now, real coke is made from coal that is baked to force off the volatiles so these gases can be used in industry. The left over is a hard sort of glassy rock which is hard to light and needs a constant air supply (an electric blower is essential or a blower slave). After saying the bad bits it is virtually smoke free as the voaltiles are not there to form the smoke and you don't have to worry about making more, its already there.

Pick your poison

Ah. that sounds like what I have. I bought the coke ready made in a 50 lb sack. I had read that the coke was easier to light, but my first several attempts left me with the impression that the whole "burning coal" thing was a hoax. I couldn't get anything to light. finally, I made a proper fire out of some charcoal and slowly added the coke after that was established. that worked pretty good. I managed to heat a 2" x 1/4" bar to a yellow-orange heat that was more than enough to bend it into the handle "eye" of the Froe i was trying to make. Had my fire been a proper size and had I waited for the anvil to be returned to its usual place, I could have actually done most of the edge tapering as well. I gave a half hearted attempt at welding the joint, but I knew it wouldn't work.

now all I have to do is build up a proper forge rather than the improvised one i had hobbled together over the cooking grill.

[ahdlm]

Industrial coke burns way slower than coal does. It's hard to light--often an O-A torch is used. It goes out unless you have constant airflow--- electric blower rather than bellows or hand crank blower suggested. And can get WAY HOT coke firepots are usually much heavier duty than coal firepots!

well, that's good to know. I had improvised a firepot for my experiment by using an old 10" cast iron skillet. can't be more than 3/16" thick on the bottom. I drilled holes and had a blower situated underneath it, but not attached. I checked every once in a while but could see no color in the actual skillet bottom, so it wasn't heating up much itself. I bought some blackpipe fittings to attach to it in order to act as tuyere and cleanout.

Im wondering if I couldn't just make a forge with a firebrick bottom rather than metal? I read that side blast would work this way fairly well.

[Rob Browne]

Fire bricks in the forge bottom are OK BUT not very portable :)