Primitive Technology: Roasted Ore and Shell Flux Smelt

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

[primitivetechnology]

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.

[LouSpowells]

Kind of crazy to think I've watched someone go from the stone age to the iron age over the course of a few years...on YouTube. Without any tricks or secret helpers, no clickbaity titles or mobile game plugs...just a mellow dude quietly and effectively reminding me of how absolutely useless I would be if everything went sideways. Thanks for the vids dude.

[vicorkit]

After 8 years, i still watch every single one of these videos within a day of them releasing. One of the greatest channels of all time, easily.

Phenomenal!

[HeisenbergFam]

8 years later and this man still finds new creative ideas to engage the audience, respect

[TheAusroar]

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!

[JugheadJones]

The thing that always impresses me most is the patience he has. It would take a full generation cycle I think for humans not to be put off and constantly aggravated from these kinds of labors in daily life! Very enjoyable and educational. Thank you.

[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.

[kshea]

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

[JerGol]

Stuns me that he has to build up a large reserve of charcoal between each smelt. The amount of work involved just in prep is huge! Incredible work!

[animelover-zopt]

Its absolutely incredible to see his improvements with making ore across the videos

[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.

[greathost]

Those huge nuggets are so satisfying to see after so many attempts yielding small ones over the years! Incredible work. Is it feasible to roast a larger quantity of ore at a time? Also wondering if you could load more of the roasted ore at a time into that tall furnace.

[MrZnarffy]

I can't wait for the day he can actually make his first real iron lump to work.. This shows how much work it is to go directly from stoneage technology to iron age. And to boot it is such relaxing videos to watch...

[Chris.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.

[abuabar]

It's funny how the other primitive youtubers just happen to get iron so easily and forge it to tools in just one video. They show no process or failures, they just happen to succeed everytime :D
I've been watching your videos since the beginning and happy to see that you still keep producing quality stuff no matter how famous you get!

[JackAllpikeMusic]

just a reminder for those who don't know, these videos always (at least every one I have watched since learning this) have captions which explain what he is doing. they're a must have to watch these videos. :)

[isaacsawka]

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.

[Soundhound]

It is a beautiful take on not just primitive tech, but experimental chemical engineering as well. Thanks for this John.

[Metrion]

What's truly exciting about seeing him experiment like this is that it is EXACTLY how our ancestors learned. Yes, he got some hints. Yes he knew that flux was a thing. But that "What if I add this to the process?" and "What if I add this to the ore?" is how humanity began its exploration of metallurgy over hundreds of years. The "I heard that the guy two villages over sacrificed his shell necklace to god of the forge and barely any iron came out" exploration.

[TheDrakenZ]

A new Primitive Technology video, it's a good day.