Pit method charcoal making

[Beavers]

Most of the charcoal making I've seen on IFI is with retorts.  I'm sure they are much more efficient and probably easier to use.  I don't have the correct steel drums handy though.  I figured could spend the next few weeks finding drums and building a retort or I could dig a hole in the ground and try making charcoal right now.  I decided to give the hole in the ground a shot. 

I found a paper from the United Nations that described charcoal making methods for developing countries.  One method they described was digging a hole, filling it with wood, let it burn for a while and then cover.  

I dug a hole about 16" x 30" and about a foot deep.  I then went over to the big burn pile of tree limbs and cut enough wood to fill the hole.  Most of it was 1-2" diameter. I got a fire started and then placed all the wood in.  I didn't pack it super tight.  After everything was burning pretty good I put a piece of steel roofing over the hole and sealed the edges with dirt.

 

 

 

 

I let it sit overnight and opened it the next day.  It didn't work very well.  Most of the wood had not burned and converted to charcoal.  I was able to get about 3 gallons of charcoal out of it. Mostly from the lower area of the fire.  So...back to Google and more reading.  I found some articles on medieval charcoal making showing the pit method using vented pits.

 

 

  I put a pipe in on one end of the pit for an air intake and dug a small trench on the other end.  Reloaded the pit with wood and got it fired up.  After it was blazing pretty good I covered it again and sealed it up, leaving the vents open.  It put out some heavy white smoke for a while.  After three hours the smoke volume was a lot less and was a lot lighter in color.  I pulled the pipe and sealed it up completely with dirt.  I figured it would be better to err on the side of under cooking.  If it's not completely done I can always fire it again.  I'm going to open it up after work tonight and see how successful I was.  If this works I have a big pile of tree limbs that will work great for charcoal making and if it doesn't work I'm not out any money.

 

[Daswulf]

Looks like a fun experiment. I see you have some of that white stuff on the ground already..... thats the weather to just have an open fire and transfer the coals.

 

[JHCC]

This might be of interest:

https://www.nationalparkstraveler.org/2015/06/art-making-charcoal-hopewell-furnace-national-historic-site26699

[Beavers]

Das, it got cold in hurry this weekend.  I'm not ready for the snow yet!  My forge is outdoors, so a nice open fire would be nice.

JHCC I saw that while researching.  Wish that was closer to home...would be cool to see in person.

EXPERIMENTAL CHARCOAL MAKING

This is the article that I kind of based my design on.

[C-1ToolSteel]

Before I switched to using actual coal, I experimented with several different methods of making charcoal. Your “plan B” method is what I found works the best. The idea is really to more or less “smoke” the wood rather than to partially burn it - just like you would smoke a brisket in a smoker. Same idea. You have a small fire (that you feed as it burns down) on one end that becomes the heat source, a large chamber in the middle filled with the wood that is being “smoked”, and a pipe on the other end to draw the heat through. Once most of the smoke is gone, you need to make sure that everything is completely sealed, so your charcoal doesn’t burn up into a pile of ash. I’d also recommend that you wait at least say, 12 hours before you open it up again. 

Charcoal making is a fun experiment and good learning experience. You will probably find, though, that after several batches of the stuff, you’ll be hooked on making ironwork and a little less jazzed about making charcoal... Look around and if your lucky, you might just find someone with a big supply of coal that they want to get rid of. If not, depending on where you live, there are still companies around that will fill your trailor with coal for a very small fraction of the cost of ordering it online!

 

[Beavers]

Thanks C-1

Would you light the wood in your main chamber or just rely on the heat from the small fire to char it?  

It's funny you mention smoker...as I was standing there watching it burn I was thinking I could probably wrap a pork butt in foil and toss it in there.  Make dinner and charcoal at the same time. 

I use a lot of charcoal in my grill too, so this experiment, if it works will fuel both the forge and the grill.

[SLAG]

JHCC,

Thanks, so much,  for the Hopewell reference.

I visited the Hopewell national historic park in the late 1980's.

 The SLAG  (L.L.P).  highly recommends the park  to any i.f.i. person that is interested in industrial archaeology.

There are many buildings, there,  as well as the ruins of a very large blast furnace.  As well as the usual park facilities. (visitors center, etc.).

The Hopewell operation did not convert their smelting  process to use a hot blast in their furnace.

By not upgrading,  It was thought to make better iron for train rails. (i.e. the rails lasted longer than standard rails). 

SLAG.

[JHCC]

They have a rather cool blacksmith shop too, if memory serves. 

[SLAG]

John,

It must have been added after my visit.  I would have enjoyed that especially, even then it was already a terrific place.

SLAG.

[Beavers]

Well I came up short again. Most of the wood didn't char again. Although I did get a couple more gallons of charcoal. I'm not giving up...fired it again and going to let it go overnight this time.

If it doesn't work this time I'm going to try a scaled down version of the Hopewell pit (mound) style.

Found a pretty cool video showing them doing it at Hopewell.

 

 

 

Another cool video from Hopewell.  I'm kinda a history geek so I find this very interesting. 

 

 

[SLAG]

Mr. Beavers, and Mr. JHCC,

Thanks gentlemen, for the information and videos.

Here's a little more about Hopewell.

The furnace was run with charcoal.

As far as I know, they did not use coal/coke.

But the iron masters and company set up one of the first industrial forest management systems.

 There was extensive forested acreage at the site. And they replanted trees regularly, and maintained their trees, for charcoal making.

SLAG.

[Steamboat]

If you feel like doing some reading, here is a link to a publication on the Vermont Archaeological Society website. Chapters 5 and 6 deal with the history of charcoal making. You may find it quite interesting.

https://www.vtarchaeology.org/publications/200-years-soot-sweat/

Al (Steamboat)

[SLAG]

Al-S,

Thanks.

SLAG.

[ausfire]

I use charcoal exclusively in my forge and our supply was getting a bit low. We considered building a drum retort, but it seems like a heap of work for a very small return. A pit is another option.

However, we have recently had massive bushfires in our area and thousands of hectares of eucalypt country has been burnt. I collected ten large bags of charcoal from one tree last weekend and I know where there are many many more. Just have to get out there and gather it up before the summer storms arrive and the grass grows up. I have drawn a map so I can revisit the area of the best charcoal deposits. Bushfires are terrible things, but where no properties are threatened, they do have their benefits.

[Beavers]

Thanks Al, that was interesting reading.

I really want to build one of those style pits now.  I'm thinking 3-4 feet tall instead of the 15 foot tall like they did.

I know there's easier and more efficient  ways to make charcoal but I have fun trying to do things the old ways.  A little bit of living history in my own backyard.

 

 

At least there's some benefit to the brush fires ausfire.  I'd be out picking it up and stockpiling too.  

[ThomasPowers]

Note that some things don't scale well. For example smaller heaps have a greater surface to volume ratio and so lose more heat in the process and so may not work as well.

When I use charcoal I like to make it and use it as I go along---I have a raised firepit I build a fire in  and I built a shovel out of gravel screen so I can scoop up the hot coals and shake out the ash and small bits and transfer the good stuff to my fire.

[Beavers]

Swing and a miss again. I still only got about 50% of the wood to charcoal. 

I do have a 5 gallon bucket of charcoal that I was able to make for no cost.  So it's not a loss.

I'm going to keep experimenting and try to get it dialed in.

[Beavers]

I took Friday off of work so I had a long weekend to make charcoal.

I started off by building the traditional three sided chimney.

 

 

The chimney was filled with kindling and the logs were stacked tightly around it.

 

With my small scaled down version of a charcoal pit the sides were too vertical for the leaves or dirt to stick.  To build a pit with the correct shape and less sloped sides would of taken a ton more firewood and I didn't want to build that big of pit yet.  So I rebuilt the pit inside the hole that I had been using for my previous charcoal making experiments.  I packed the wood as tight as I could.  The chimney opening was covered with a piece of 1x10 prior to covering the mound. 

 

 

It was quite windy and the leaves were blowing off the pile as fast as I could add them.  I've read that Colliers also used grass to cover their pits if it was available, so I used hay.  

 

 

I then covered the pit with a couple of inches of dirt.

 

I removed the "brigen" chimney cap and dropped a shovel full of hot coals down the chimney to "fire the pit".  The pit was fired about noon on Friday.

Covering the pit was traditionally called "leafing and dusting".  The dirt that I used was dug from the ground and had some moisture in it.  After packing it down I think it sealed too tightly and didn't allow the pit to breathe as much as dust would of.  I ended up having vent holes opened in the pit during the entire burn.  

The pit never put out a ton of smoke, it was just slow lazy wisps of smoke from the vent holes.  The pit burned overnight with no holes opening up in the cover.  

After burning for about 24 hours I "jumped the pit"  and walked over it tamping it down with my feet.  One section sank about six inches suddenly when I stepped on it.  I can't imagine how dangerous and nerve racking that must of been for the Colliers jumping their 15 foot tall pits.  One wrong step and they would of fallen into the fire.

 

The pit continued doing it's thing smoking all weekend.  Unfortunately I have a job and had to work on Monday, and I didn't want to leave it burning unattended while I was gone at work. So Sunday afternoon I sealed up the vents and let it cool down a few hours before I opened it up.

I was hoping for buckets full of wonderful charcoal.  Turned out that only about 40% of the wood had converted to charcoal.  I'm guessing this pit would of needed to burn for about a week.  While I didn't get a ton of charcoal out of the deal I still think it was successful.  I learned a lot about the history of charcoal making and had the kids involved in the process too.  Probably not many other 8 and 6 year old kids that know what a collier is, much less can say that they helped with  a traditional style charcoal pit. 

I want to continue making my own charcoal but until I can retire and have the time to watch my pit for a couple of weeks I think I'll be using some steel drums.

 

 

[Steamboat]

Sounds like it was a fun and educational experiment. I might eventually try something similar, since we have literally tons of free wood to work with and a large wide-open space to do it in, as well as some heavy equipment to move soil, etc. However, there are several projects in the to-do list that are ahead of it, so it might be a while.

Al (Steamboat)

[Glenn II]

As Ausfire is getting ready for summer, I am preparing for winter...I use an outdoor wood boiler for primary heat for my house. Day time temps have been around 50 F, so mostly just running the boiler at night.

  I ran out of charcoal last weekend, and was disappointed my project would have to wait until the next time I was in town to buy some. I thought about making some, but as has previously been stated, I'd rather be Smithing than making charcoal. 

That's when I remembered as I checked my boiler in the morning to see how much wood was burned over there previous night, the nice bed of glowing "coals" that had been left behind. I started saving those nice little nuggets, I put them in a metal trash can with a tight lid and let them cool. Easy, "free" charcoal.

It helps with the moderate temps that the boiler doesn't run too often (it cycles based on water temperature) so if the blower fan has been off for some time and the inlet damper shut, I have some decent sized chunks of charcoal to transfer to my can. The bigger pieces break up pretty easily. If when I go out in the morning and find the boiler firing or recently having fired, I flip the electrical disconnect switch and transfer after I come home from work.

It's a little like robbing Peter to pay Paul...I loose a little heat for my house, but it feeds the fire in my soul, and warms the anvil a bit too!

[ThomasPowers]

I sift the ashes from our woodstove; but last year my wife said it was so warm she only had about 4 fires---after she bought two cold winters worth of wood to add the the winter's worth already there.  (Passive solar house with woodstove backup + we like watching fires...)