Water Bellows smelt
Added 2024-09-05 22:01:21 +0000 UTCI tested the water bellows with an iron smelt and it made 5 g of cast iron droplets, proof of concept that the bellows works. There are still teething problems with the new method but it shows potential. Much appreciated.
Comments
I tried to smelt ore directly in a pottery kiln years ago (before I started the channel). I put an ore brick on top of the pottery and it didn't get hot enough to melt to slag. But it did roast it quite well even though the ore was on top of a batch of tiles. It still gets red hot at the top of the kiln which should be enough to drive off moisture and possibly any sulfur present. I may attempt it some time. For the specific roasting furnace design, I'd say even lining the bottom of the cross draft with clay to form a clean floor and firing it before pouring the ore sludge in would be enough, no need for pots to hold the ore. No problem all good suggestions, much appreciated for your patronage.
Primitive Technology
2024-11-11 22:10:08 +0000 UTCAhh, I see, I see, I guess I was being excessively optimistic about the temperatures needed and the flow of heat produced in the current kiln. In my head, gaps around the 3rd brick level leading into the "oven" (in the diagram) or even tuyeres, would be enough to roast the ore, I do agree with you that getting clay containers of wet ore dried by kiln would be good (if you had enough) I guess just placing fired pots with wet ore around the kiln (where I put the oven) would be enough to boil / dry out the ore quicker? Maybe. Also, I appreciate your patience in responding to my probably obvious thoughts on this :p
James Tyrrell
2024-11-11 21:30:13 +0000 UTCI see, you meant a separate room outside the kiln, it's a good diagram. The issue with this design is that the flames would need to be drawn up through the side box as well as the main ware chamber and it would be too taxing for the existing firebox. The additional ore chamber would need its own firebox underneath to get flames up through it rather than rob flames from the pottery. A square or circle are the best floor plans for updraft kilns because they are more efficient to heat (circle is best but square is better for stacking but closely approximates a circle in terms of heat loss). I'd say it would be best to put the ore on top of the kiln and cover it with pot sherds. Historically, there were ore roasting kilns built just for the purpose. They tended to be cross draft kilns in design and were basically reverberatory furnaces, with the ore sitting on the floor of the kiln. I had considered building one just for this task so that the wet ore could be poured in and dehydrated/roasted at the same time. But I didn't have enough ore to justify building one.
Primitive Technology
2024-11-11 21:15:14 +0000 UTCAh, all good points I guess I thought of a separate section just make it easily separated from the pottery / firing process, I'm not sure what temperatures the kiln reaches and whether you'd start smelting rather than roasting. no reason you couldn't just mix ash in with the roasted ore, you could try varying amounts of ash to experiment what ratios create the best slag/results. Partially it was also due to the ease of making/trying it, you just need to use some of those bricks you already have I suck at describing things, so I drew a picture: https://drive.google.com/drive/folders/13hT15t5JpE_kBSkgu4_5_a31oS6Su_bf
James Tyrrell
2024-11-11 20:52:02 +0000 UTCOne more thing, wood ash added during the roasting process in a pit fire might help during the smelt. I remember getting a good result after roasting ore that had the ash mixed with the ore. The slag was a lot more glassy and the iron prills were bigger from memory. In a kiln, ash wouldn't be added to the ore. I've also read ash from charcoal in the smelt can effect the properties of the slag. Ash is used in pottery to lower the melting point of silica to form a glaze, so the addition of ash to ore might behave like a flux. This might be an important consideration. Thanks.
Primitive Technology
2024-11-11 20:32:00 +0000 UTCIf I were roasting ore in the kiln, I'd put it on top of the bricks and pottery rather than a side extension, it would be easier that way. There's no reason not to and it should roast the ore well, a kiln is a good tool for roasting ore. The fire at the top of the kiln is hot enough and oxidizing, so it might be a good use of waste heat before leaving the kiln. The ore also gets a bit brittle once roasted, so it might be better to have it on top rather than in a load bearing role amongst the pottery down lower. I guess the reason I fired it in a pit is because it's a separate project from the pottery ones. I once roasted ore in a charcoal mound and it worked too. There, the conditions are reducing rather than oxidizing. From memory I don't think it changed the results of the smelt, driving off moisture seems to be the main reason for roasting. Thanks.
Primitive Technology
2024-11-11 20:25:57 +0000 UTCI had a question about the Iron ore brick roasting is there a reason you haven't put an ore roasting extension on the side of your brick kiln so when you're firing bricks, tiles, pots etc, you're also roasting ore. I think you could just stack bricks on one side of your existing kiln with a space underneath (for the roasted ore collection) open up a few vents to the main kiln and then use mud to seal of the Ore roasting area. just put the iron ore bricks in there whenever you fire pottery.
James Tyrrell
2024-11-11 18:38:53 +0000 UTCThanks for the answer and the suggestion. To your point about artificial ore, I once used the primitive blower design at home with iron oxide (bought from the hardware store as red cement colorant) and mixed it with corn flour and water to form pellets. It is indeed a better ore as almost all of the material that came out of the furnace was shiny metallic iron when polished with the grinder. But mine was smaller though mostly in one porous lump. But it was likely cast iron also. Yes, cast iron is easy to make but softer iron is difficult for me. I managed to make forgeable iron in one video by melting the cast iron prills in an open hearth. I think I've heard hemp bellows were used some times and sealing it with some local latex sap might work. One more link if you're interested, I found an old diagram of a water bellows from 1736 in Sweden, the text is hard to read but I think it says it was used in place of large leather bellows: https://makingscience.royalsociety.org/items/clp_3ii_37/paper-description-of-a-new-invention-of-bellows-calld-water-bellows-by-martin-triewald?page=1 .
Primitive Technology
2024-09-07 23:33:32 +0000 UTCAll fantastic answers, thank you. Using the great-bellows worked well, but I think this was ONLY because I had lots of help. if I had to do it on my own, I'm pretty sure I would have failed miserably. I should also note that for that smelt, we were cheating and using commercial iron-oxide that we mixed with clay to form pellet balls, intermixed with charcoal (that i did make myself) in a bloomery furnace. The final bloom was roughly basketball sized, so a decent bit better than 5 grams ;) Another time at an ABANA (Artist-Blacksmiths Association of North America) convention, we were using a documented Swiss process intended to turn ore directly into high-carbon tool-steel, and managed to go overboard and ended up producing cast-iron. But that's because we were using an electric blower. Still, it was properly harvested bog-iron ore that time. If you wish to avoid leather, you can get a substitute by looming cloth and then saturating it with plant-resin. Rubber-tree latex is the gold-standard, but I know that's not local to your area. Personally, I find leatherwork extremely satisfying; I've only done leather-tanning once (beaver-hide), but traditional vegetable tanned leather is a joy to work with.
Paul Grodt
2024-09-07 22:10:58 +0000 UTCYes, another pot filled with sand or soil would probably work.
Matt Lohafer
2024-09-07 18:23:36 +0000 UTCThanks I'll look into it. The displacer would have to be the same volume as the bellows.
Primitive Technology
2024-09-06 20:23:01 +0000 UTCYou could remove the need to move the bellows itself if it was in a basin of water, and you raised and lowered a displacer into the basin to move the water level. That would lessen air loss at the tuyere, and have less chance to drop the pot bellows. A longer stroke would also help the smelt by providing a more constant draft and keeping the temperature higher in the furnace.
Matt Lohafer
2024-09-06 15:38:14 +0000 UTCJust a question about leather bellows, did the one you made produce a good bloom? I'm interesting in hearing how it went.
Primitive Technology
2024-09-06 08:46:58 +0000 UTCI made some videos based on the stack effect or natural draft (https://youtu.be/Fn9tmm-_yAI , https://youtu.be/U7nqBgklf9E , https://youtu.be/u7wAJTGl2gc ). The first link is to the attempt that made the most iron, albeit smaller than from my forced draft attempts. Also, natural draft furnaces were used in many parts of the world for iron smelting in ancient times and more recently in Africa with some extant example still around (search natural draft iron smelting Africa on google for some examples).
Primitive Technology
2024-09-06 08:45:32 +0000 UTCThe benefit is that it doesn't need leather to make. Clay and water are more ubiquitous materials so it can be made in more environments. Also, it makes a perfect seal with water where as stitching leather allows for air leaks. The centrifugal blower I made has more moving parts and would often seize during use meaning the smelt needed to stop to fix the fan. Also, rope is used up quickly with the blower due to wear on the rotor.
Primitive Technology
2024-09-06 08:38:32 +0000 UTCSo this is certainly interesting and a good watch, but I don't quite understand any benefit this has over the very common leather-bag bellows, the less-primitive great-bellows (I made one for iron-smelting in the past), or the relatively modern centrifugal blower that you've already made (I currently use one and love it for 19th century blacksmithing). Out of curiosity, have you investigated into smelting that makes use of the stack-effect from a sufficiently long chimney? I can't remember my source, but IIRC, it was one of the advances that allowed the bronze age. Building a long chimney-stack, typically against a hillside, could be primed to the point that it could draw enough air to hit smelting temperatures without any added work. I've never seen one in action, though I have visited the remains of a couple 18th century pig-iron furnaces near me. Granted, they were all made to function on a much larger scale, and either operated 24/7, or risk bankruptcy if forced into an unexpected shutdown. I'd love to see the more primitive smaller scale situation if that was at all feasible.
Paul Grodt
2024-09-06 07:51:05 +0000 UTCAs it is now, it's demonstrably not. But I think it has potential and could be made more efficient and more reliable than the fan blower. The method has fewer moving parts and rope is not needed to get it to work as it does with the one way blower. Before each blower smelt, lots of rope is needed as the friction against the rotor wears it away with use. I think that making the water bellows taller will give it a longer stroke and potentially more pressure as it can be plunged deeper into the water. Thanks.
Primitive Technology
2024-09-06 00:52:17 +0000 UTCDo you think the water bellows is more efficient then the one way blower?
Sam Gordon
2024-09-05 23:50:40 +0000 UTCYes, I was thinking of that. There are diagrams of such bellows being used. The lever could have a weight on one side opposite the side being held so it drops automatically. The pots are already heavy so they wouldn't need weights. Thanks.
Primitive Technology
2024-09-05 23:19:47 +0000 UTCNow you can put 2 together on a rocking beam. With an overhead pull. Fix it so as you pull down one bellow is blowing while the other is filling, as you release the pull it reverses.
Kenneth Crips
2024-09-05 23:13:50 +0000 UTC
