Primitive Technology: Roasted Ore and Shell Flux Smelt
Date : May 4, 2023

Primitive Technology: Roasted Ore and Shell Flux Smelt
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About This Video:
I tested 2 ways of improving iron smelts by treating the ore, roasting the ore and using snail shells as a flux. Then finally I recycled old slag to see if it would produce any more iron.

The first way was to roast the ore before smelting. This drove off the moisture and volatiles in the ore as well as burning off any sulfur present. The resulting ore produced a higher yield of iron than normal (33g iron as opposed to about 15g iron as usual for the same volume of ore, charcoal and time).

Next lime was added to the smelt as a flux in the form of snail shells. The theory was that the lime would lower the melting point of any silica in the ore to make a runnier slag and help the iron come together more. The result was very bad, no iron was produced apart from 1 or 2 prills. I suspect the ore is already basic in chemistry and adding a basic flux in the form of lime made it so basic that the slag was too viscous. The ore probably won't benefit from a basic flux but might benefit from an acid flux such as sand or slag from previous smelts.

Next I tried smelting slag from previous smelts to see if anymore iron would come out. It did surprisingly, less than fresh ore but still worth doing. For this reason it might be useful to add old slag as a flux to future smelts to help the slag form more easily, while contributing some more iron to the smelt.

About Primitive Technology:
Primitive technology is a hobby where you build things in the wild completely from scratch using no modern tools or materials. These are the strict rules: If you want a fire, use a fire stick – An axe, pick up a stone and shape it – A hut, build one from trees, mud, rocks etc. The challenge is seeing how far you can go without utilizing modern technology. I do not live in the wild, but enjoy building shelter, tools, and more, only utilizing natural materials. To find specific videos, visit my playlist tab for building videos focused on pyrotechnology, shelter, weapons, food & agriculture, tools & machines, and weaving & fiber.

#PrimitiveTechnology #RoastedOre #ShellFlux

Category: Far Away | Far Away | Fun | Survival


  1. K Shea

    Honestly incredible that humans figured out how to make metal at all, or even find out it existed in the first place. Cool stuff

    • Ti R²

      adding to all the previous comments, also bear in mind that one guy alone for ~10 years doesn’t even come close in “discovery capacity” to large, functioning communities over millennia. give humanity time and friends and we can do everything.

    • nunya bisnass

      Was probably an evolution of successive accidental discoveries beginning with terracotta. Pot boiling water breaks over the fire, fire is too precious to retrieve the pieces, once fore does down disciverbrhe pieces are much harder and more durable. Then they painted them by crushing minerals and/or using clausbfrom different areas noting they had different properties and discovered some minerals gave a metallic sheen or sweated out of the bricks or other terracotta items when they got really hot.

      I’m sure someone has a better idea than my speculations, but I agree it’s still amazing.

    • Tom Blaise

      There’s a thing called “natural copper” that can be worked right out of the ground, no smelting needed. This likely was the first interaction humans had with metals. I’m not sure about sources in the old world, but native Americans around the great lakes had a source of natural copper they would work with stones without any smelting for thousands of years.

  2. Primitive Technology

    I tested roasting the ore, using lime flux (shells) and recycling slag in 3 separate smelts. Roasting the ore improved the yield about 2 times though this might have been due to decreasing the volume and effectively increasing the concentration of the ore. Adding lime (snail shells) ruined the smelt and produced next to no iron. This may be due to the ore already being basic and chemistry and the lime made it so basic that the slag won’t flow. Sand (an acid flux) or old slag might make a better flux for this type of ore, lime might be better used to flux iron sand (acidic due to the silica content). Finally, I tested re-smelting the slag from previous smelts (not the slag from the lime smelt). The result was about half the iron came out compared to fresh ore, which suggests that slag should be smelted again to recover any iron not obtained during the first smelt if fresh ore is hard to come by. Thanks.

    • William Serba

      1. Melting points: Potassium Carbonate 891C, Sodium Carbonate 851C, Calcium Carbonate (calcite)1339C.
      2. Primitive Technology has everything he needs to make a tenmoku style glaze. 60% flux, 18% shells, 12% clay, 12% silica , 10% red iron oxide
      3. If you took wood ash, and washed it with water the sodium and other fluxes will dissolve into the water. You could then boil off the water and have a relatively pure flux. This concentrated lye causes burns.
      4. soap

    • MrRivensteel

      Do you have enough nearby water flow for a trompe to assist your air pumping?

    • AM D

      @Primitive Technology The iron bacteria cement one. Not a big deal but I think you might find learning about the topic (bacterial catalysis of metal redox cycling) interesting!

    • Corey Merrill

      Beeswax is another natural flux. Smelting with two or three green leaves from a nitrogen fixing plant also helps , it creats a nitrogen atmosphere around the metal sponge when sealed Ina clay pot .further reducing oxidation.

    • Михаил Новиков

      ​@Primitive Technologyдавно смотрю ваши ролики. Согласно историческим находкам болотное железо – болотную руду – лемонит обжигали не россыпью, а измельчали и пекли в горшке в обычном костре около шести часов.
      Есть русский канал “Кузница Вёлунда” там настоящие кузнецы отковали меч викингов полностью по историческому процессу, от сбора руды до изготовления наковальни

  3. ladyofthemasque

    The chemical used to lower the melting point of the slag (unwanted materials, also called dross) is calcium oxide. Wood ashes contain calcium oxide, as does pre-burnt shells, and limestone that has been baked into quicklime has the most calcium oxide. Since he’s in an area with no limestone, he only has ashes and snail shells to work with. The failure may have been due to the fact the shells were merely crushed, and not pre-baked, as happened in a previous experiment (turning snail shells into the calcium oxide / hydroxide needed for making cement) several years ago. Or it simply could have been too much calcium oxide, because yes, sometimes too much of a good thing is actually a bad thing in the end.

    • Diego Reig


    • Diego Reig


    • $XEN

      we got game genie over here

    • dally b

      I’m sure this is a dumb suggestion, but is there anyway to make a crucible and just put the ore in it and then heat the crucible with the blower?

    • Lemtil

      @dally b Not really, just beyond the scope. If you aren’t specifically trying to do gas flow reactions, crucibles are for casting. Ceramic crucibles are made with chemically purified compounds, carefully designed by chemical/material engineers, and degassed with vacuum chambers.

      There’s a possibility that someone given enough time could flow chromatographically isolate the correct silts, combine them in the correct ratio with extremely fine bone powder, and work it all underwater to prevent gas inclusion. But feasibility is a problem.

      Also working backwards from a modern perspective probably isn’t really aligned with the motivations here.

  4. Hippolyte Guillard

    I cannot begin to explain how much I love the fact that you include failures into the videos. That honesty and scientific approach is why it’s so interesting.

    • Martiddy - Sama

      Is like watching Dr Stone in real life

  5. XplosivCookie

    I’m not as excited about anyone else’s uploads as I am of these. On one hand, you keep posting amazing interesting videos so it might be a bad idea to rush that, but on the other hand I hope it won’t take a full month to see the next video.

    Do you think you’ll shape your next iron piece the same way as the knife? You don’t have many ways of handling the material while it’s hot, but surely you’ll have to strike the iron at some point ^^

    • Primitive Technology

      Possibly, either cast iron or forge it, I’m experimenting. Thanks.

    • Cashel McKenzie

      @Primitive Technology I am so keen to see you try any type of anvil, I cant think of anything but im sure you have, cant wait to see!

  6. Lyon

    All this experimenting with iron ore and smelting is so fascinating, looks like you made some great breakthroughs this video!

  7. Luckynmd

    OMG! It’s incredible to see the collection of metals you’ve produced so far! Think of how many wood sticks it took, this is so many hours of hard work! 🤯

  8. nuketeacup

    How is wood gathering handled? Do you have a specific area you harvest, or just collect whatever is available/convenient? Smelting seems like an extremely resource intensive process so just curious how resource management is being handled. Thanks for years of incredible content, probably my favourite youtube channel of all time!

    • Ithilion

      @Obywatel CG Even if he is burning wood, his hobby still remains orders of magnitude more carbon friendly than any other “modern” ones.

    • Dan

      @Obywatel CG If you want to be that pedantic, your respiration is also adding co2 to the atmosphere, so you better knock it off.


      @Obywatel CG he is burning dead wood he finds around his hut. he effectively lowers the chances of a wild fire destroying the land around him. Dead wood will burn, it just depends on when. Controlled burns are better than wildfires.

  9. PropheZ23

    As a blacksmith and custom knife maker I absolutely love watching videos like this. Thanks for sharing this!

  10. Christopher Cook

    Man, DOUBLING your yield really speaks for itself.

    I really enjoy that you’re taking viewer suggestions seriously. I remember in previous Q&A comment threads commenters suggesting roasting pre-smelt, the lime shell thing, and others.

    Obviously, not all of them are worthwhile, but you can’t argue with the results of that first experiment.

    • J K

      I’m just waiting for this guy to gather enough iron to start making weapons and armor. Iron Age here we cooooome!

    • Ageis Hyena

      This. Who knew shells were a bad idea. I thought it’d help separate the slag from the iron itself.

    • StarGaming

      @Ageis Hyena I think it still does but if I remember right you have to add it to liquid metal, not just ore at the beginning. That might or might not be correct idk

  11. Roadkill 94

    Dear John.
    As a metallurgy engineer that handles ore into kiln, I have the following advice:
    I suggest you start with smaller fire and continuously build it up to increase the temperature, but it is important to keep a calm fire after starting it. Drying the ore slowly is the key to a nice and ready charge for the coal. Once you start adding coal (after 3-4 hours of drying the ore), I suggest you try making breaks while blowing, to let the coal and the charge cook well, like cooking a steak at a low temperature, because too much air will oxidize the iron earlier before it reaches a temperature near liquid phase before smelting, so that could be the problem why you are still getting small prills. Try making small pellets of 1 cubic centimeter of the ore. Burning the iron ore right from the start will cause the iron to pop and form into smaller prills into the slag.
    Also lime is added in liquid metal only (from my experience so far)
    Hope this helps!

    • Charlie

      @Garry Sekelli He should just buy a knife from the store! So much easier

    • kalibisaboss

      @potato4dawin someone did not understand the joke

    • BCzepa

      can you put a big rock (preheated) with a depression to catch and concentrate the iron? (the intense heat would probably crack it)
      as you add iron can you chuck in half golf ball size rocks in one side of the chimney? my thinking is: this would accumulate radiative heat and create a less oxygen rich portion of the chimney. even diffusing the air by covering the tube with chunky gravel? maybe crush some of the charcoal to mix into the dry powdered ore. i would get it 3/4 full, burning hot, then add layering of charcoal and your ore mix all at once, then slow and consistent till finished (smaller coal chunks at the end too)

    • David Ryan Sargent

      You said exactly what I was thinking 😉😉

  12. Corey Grandmaison Archive

    These videos and the massive amount of work that goes into them is legendary. It’s incredible you’re smelting at all and testing out these methods per the iron bacteria. Massive respect.

  13. Kozu

    I’d just like to add a comment of respect for the sheer amount of work that goes into producing what to us is an 18 min video. The bricks, the wood gathering, the many batches of charcoal production you must have done, the iron bacteria straining. You make it all look so easy but I know from personal experience that it is not. Best channel on youtube, I’m excited every time a new video drops.

  14. AM D

    I just love the handmade primeval aesthetic of everything- knowing that dish at 8:37 is something you made from earth you dug up and shaped and treated yourself- the charring on the mud brick walls as you fire iron ore you’ve dug with charcoal you’ve made- and it’s also always surprising to me what a substantial looking building you can make with just earth and ash- the tiling of the roof is particularly impressive, it’s just a more rough-hewn version of roof tiles you see today

  15. Eret

    One of the only channels that I will drop everything to watch a new upload. Love seeing the development!

    Also, remember to turn on captions during the video 🙂

  16. Isaac Sawka

    This channel is an inspiration. I’m not sure I could’ve pushed on after that lime smelt failure. The amount of effort, perseverance, and discomfort to push through that entire process only for it to end in a less than optimal result would’ve set me back. I’m sure off camera there’s some moments of frustration expressed, but the tossing of the ore was the only bit we see of possible catharsis. Thanks for pushing through and showing how to enjoy your hobby even when it’s difficult.

  17. L0rdph0b0s

    you continue to be one of the most enthralling channels I’ve ever seen. Your dedication is now only outmatched by your ever expanding repertoire of skills. Please continue this as long as it brings you joy my friend. because it will bring joy to all of us.

  18. ZXNOVA

    So cool watching him get more efficient with iron yield experience. Everyone seems to talk about making knives or hatchets or something, but after so many iron videos, I’d be curious to see more experiments with food as well as pottery… perhaps a potter’s wheel.

  19. Gala Fawkes Random Stuff

    over years I’ve watched this man cut down probably hundreds of trees to run his furnaces, and all with a simple rock axe. so epic. please keep this amazing content coming, I learn so much watching these videos

  20. Teo Medeiros

    Aguardando ansiosamente pelo próximo vídeo! Parabéns por este trabalho!

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