Roasted Ore and Shell Flux Smelt
Added 2023-05-04 21:01:32 +0000 UTCI tested the effectiveness of roasting ore and using lime as a flux in iron smelting. First I roasted the ore and then smelted it. This gave an improvement in yield. Then I collected snail shells as a source of lime (calcium), crushed and added it to the ore and then smelted the mixture. It produced nearly no iron at all. I think this is because the ore is already basic and adding a basic flux made the slag more viscous to the point any iron that did form wasn't able to come together to form nuggets. Finally, I smelted the slag from previous smelts (not the slag from the lime smelt though) to see if more iron would come out. Surprisingly it did, there is still iron in the slag though it was less than fresh, roasted ore. I also tested a taller furnace in the two latter smelts and didn't noticed a difference in efficiency. Much appreciated.
Comments
True, I was given lapidary quality copper ore from an African country (the green mineral they saw in half to make jewelry) and smelted it. It produced almost a half by weight in copper just in a small pit fire with the blower I use for iron. Good ore makes a difference.
Primitive Technology
2023-05-26 21:09:02 +0000 UTCIt is too bad you don't have copper ore of some sort in your area. It was a big technological leap from Copper to Iron smelting.
Kenneth Crips
2023-05-26 15:51:46 +0000 UTCI could probably make one from clay, I've thought of it. Less carving and better control over shape, plus less likely to burn or rot. Thanks.
Primitive Technology
2023-05-08 02:21:09 +0000 UTCYou might try to build a modified Japanese fukisashi (box bellow) It is mostly beyond the technology level of your show but there is no reason why you could not make one with a hollowed out log. I have not seen any is there any bamboo in your area? Box bellows have been in use in South East Asia for 1000's of years.
Kenneth Crips
2023-05-08 01:46:10 +0000 UTCI'll try it some time and see how it goes. Or make an actual venturi shaped venturi (narrow waist with air holes in it). Thanks.
Primitive Technology
2023-05-05 20:19:20 +0000 UTCWhat about adding a constricting nozzle to the blower before a normal sized tuyere to increase the pressure?
Judah Sher
2023-05-05 20:11:24 +0000 UTCI've pulled the blower back from the tuyere to leave a gap and it didn't seem to make a difference. There might be issues with air pressure dropping despite a larger air flow and the blast might not go into the fuel bed as far. I also tried a large diameter tuyere and the smelt goes slightly quicker but the iron is slightly smaller and spread out. Thanks.
Primitive Technology
2023-05-05 20:03:56 +0000 UTCYes, I think lime might be better added to ores such as iron sand which contain relatively more silica. Also yes the wood ash contains bases that would lower the melting point of silica. Wood ash was used as a flux in "forest glass" during the medieval period and as a glaze for pottery as well. Thanks.
Primitive Technology
2023-05-05 19:59:41 +0000 UTCApologies if this has already been suggested, but have you tried using a larger tuyere with a gap around the blower? I’m thinking this could use the venturi effect to increase air flow.
Judah Sher
2023-05-05 17:37:06 +0000 UTCSigned up just to comment here. I love your work and have followed for a long time. I have a background in cement manufacturing analyzing the chemistry and mineralogy so maybe I can help with understanding what happens if you have questions. Pasting my youtube comment below since I guess better chance you see it here: I think there's two reasons why the shells didn't work. First of all the iron source is bacteria, and while there is silica with the bacteria, I am not sure if the concentration is actually that high. Secondly the wood ash is also rich in calcium, so adding more calcium from the shells probably just oversaturates the mix. The result will be the formation of calcium silicates, but also calcium ferrites. First Ca2Fe2O5 and later Ca4Fe2O7. These are flux minerals known from the cement production process, (but do not contribute to strength development from cement).. It should start forming already at around 1000C with excess Calcium oxide available. Without knowing the silicate content in the ore it will be hard to balance the calcium, but I doubt you need more than what the wood ash gives. Maybe even less than that, as the char coal also has calcium in the ash
Morten Bjerkvig Jølnæs
2023-05-05 16:49:35 +0000 UTCThat's a daunting amount of work. You just about need a village to support a blacksmith industry, there wouldn't be enough hours in the day for one person to hunt, gather AND manufacture!
Amy Tobol
2023-05-05 14:05:16 +0000 UTCCollecting the ore takes about a month depending on weather, more ore can be found in the dry when the paste thickens. Charcoal making can be done in one day and taken out the next. There's maintenance as the sting keeps breaking and so I usually like to have 5 m of string per smelt to drive the blower impeller. Roasting the ore takes a few hours but you don't need to be there as the burn happens automatically. The smelt itself takes about 2 hours, 1 for wood preheat and 1 for the smelt with charcoal and ore charges. Thanks.
Primitive Technology
2023-05-05 09:36:32 +0000 UTCThat's quite an achievement. I've only taught 2 people fire making with the hand drill, the rest can't do it. Yes, agreed, sitting half cross legged with one foot on the baseboard is the best way I've found, kneeling takes more effort. Thanks.
Primitive Technology
2023-05-05 09:32:26 +0000 UTCGreat work! Congrats! How long to do all the process?
Lucas Costa
2023-05-05 09:02:45 +0000 UTCThank you for the full fire-making sequence! I love the way you make fire. You're the only one who sits that way. I was having trouble with stamina and mobility, when I first tried to make fire, I couldn't hold that kneeling position that other fire drillers hold. But when I sat on a step, and emulated your position, I found I could stay that way long enough to get the ember. What an amazing feeling, to see that ember burst into flame!
Amy Tobol
2023-05-05 07:31:51 +0000 UTCOnly one way to find out, though the prills are so precious at this time I hesitate to do so. There is scrap iron from previous smelts though that I've tried forging and I have considered re-smelting it together with new ore and old slag. I've planned an experiment so that slag goes in first as a flux, then fresh roasted ore and then scrap iron from previous smelts. As I understand, it may be better to form a molten slag bowl first before adding the metallic iron as this protects the metal from oxidizing. Then as you suggest prills might weld to this to make a larger iron mass. I'll try it some time. Thanks.
Primitive Technology
2023-05-05 00:07:02 +0000 UTCGreat video! I wonder if incorporating prills/nuggets from successful smelts into the charges of pre-smelted ore could increase yield? I'm not an inorganic chemist, but maybe having pre-formed metal lattice would help nucleate crystallization from nearby ore, instead of it just going into the slag? That might be part of why the shell lime didn't work as well, maybe the heterogeneity made it harder for prills to "seed" crystallization of their neighbors? Sorry for the ramble, thanks for the video!
Pinkus McEverclear
2023-05-04 23:27:01 +0000 UTCI'll try it later, just roasting the ore the way they traditionally on a open heap of timber. It doesn't need to mix with the ash, there are special ore roasting furnaces that are essentially cross draft kilns which keep the fuel and ore separate during roasting. Thanks.
Primitive Technology
2023-05-04 23:15:02 +0000 UTCVery interesting thanks! Why did you put it in the fire and not in a container? Could you roast the ore in the ceramic dish you had it in for example? Does it need to mix with the wood ash?
Ken Clark
2023-05-04 21:43:46 +0000 UTC
