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I Forge Iron

coal quality

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Having been recently corrected by Irnsrgn on a quite a basic coal issue,alerted me to a possibility that i may not know it all,afterall...unbelievable,but hey...Let me quickly run down my definition of usable coal:Whatever they sell me at the local(350 air-miles away)feedstore.Their supply has changed twice,so far,and each time for the best(in my book).The reason i especially like the latest stuff is twofold:(1)It allows me to start welding almost immediately after the fire's built,even if i overworked it the night before,leaving meself short on coke.(2)I can continue welding even when a large and gnarly clinker lurks in the bottom of the pot(bottom-blast,of course,god knows why,after all these years).All that has led me to presume that the coal does not contain any metals or other elements harmful to the weld,which is all i ask,as,needless to say,the stuff kicks out plenty of heat for normal forging.But now my blissful reverie is shattered-seems like the stuff(on the other side of the fence)makes ash,not clinker,and is BETTER.How better?There is a very decent looking local coal that makes ash,and 1 (great)heat is all i get out of it,so assumed that ash/air intake are at fault.
So,any thoughts on the matter?Would appreciate any informed input.Have to emphasize that forge-welding is central to what i do,especially currently,and good-size stock,too.My cast pot is normal size,but often have to dig out the clinker and re-build the fire 2-3 times a day,it's working overtime,constantly...

Thanks in advance,Jake.

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The first part of your difficulties you have already answered, you have some stuff that works and you have had some stuff that doesn't.

The rest is academics. I have been in the same place having bought two truck loads of top quality coal from two different seams and have used what is available locally. The pocohantas puffed up light and fluffy like jiffy pop and would weld quick and easy, make a little ash and a little clinker. The sewell seam was very hot welded easy and made almost no clinker but a LOT of ash that was indistinguishable from the fines which was what most of it was. The local coal was anthracite or durn near, would weld pretty well makes a fair amount of clinker and ash likes to go out or not get real hot if not fussed with more than the others.

Each of the three serves us well at different prices. I'd stick with the Pocohantas if I could afford to have it trucked in. As for the impurities there is some coal that will kill your steel, I have used some of that as well.

There are some websites on the various assays of coal, Penn State had one but I couldn't find it just now. Wikipedia offers some depth to it, easier to read than a lot of the stuff at the universities. None give a definitive this is good, this is bad. Depends on the application. For a blacksmith with a bottom blast it is good and desirable to have the clinker form solid and small at the bottom easy to get out, and low amounts of ash just flying around, popping out of the fire whenever you get close.

I have never used coal that only made clinker or only made ash, but the poco came close on the clinker and the sewell on the ash. and then the junk that took all available heat to make clinker and ash left our steel cold and lifeless. No wonder it was free.

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BP0051 Good Coal
BP0131 Coal, Coke, and Rocks

Good coal for blacksmithing is low ash, low sulfur, high BTU coal of a usable size for the forge. The numbers suggested for good coal are less than 7% ash, less than 1% sulfur and above 14,000 Calorific Value in BTU's. These are not hard numbers but guidelines.

Available analysis shows ash content of coals listed from 3.7% to 22.4% ash, sulfur from 0.4% to 3.3% , and BTU's from 8,467 BTU's to 15,500 BTU's Calorific Value.

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O.K.,I've read over all that 3 times now,trying to internalise all that data,and will continue till it finally settles itself in my pea-brain.
Mills,what you've described makes a lot of sense,thank you most kindly for taking the time.
Glenn,likewise,i really appreciate the info,and will be looking at these links forthwith.
I have more questions that i'll do my best to sensor so as to save everyone the time,but one i just can't resist:Would a side-blast minimise the problems with the given solid fuel,both clinker/ash wise and the undesirable element content?Please excuse my naivette...not sure how it works-the more years go by at the forge.the more questions seem to come up...
Thanks again,your advice is not going into the vacuum,will try to incorporate as much of it as i can.Am just about to take the lid off of my first experiment with the close-retort charcoaling,spruce,this time.Will be trying birch,then cottonwood,next.The plan is to do it in same size batches,and try to clock the forging time with each of the results,for comarecent.

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I've never used a side blast Jake but would suppose that you would avoid a build up of nasties that chokes the air. I've seen your shop on MAF and as resourceful as you are do as Glenn suggests, knock one together and give it a whirl. A pipe on the blower, propped on some brick or wood just use your current forge as it is. I think that'll do more for you, since ultimately it is a matter of what works well for you with what you have available.

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