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How humans discovered the use of metals.


Robittybob1
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How did humans discover the use of metals?

 

I don't know but let's see if we can make sense out the clues discovered so far.

 

Stone knives and spears gradually turned into metal knives and metal spear heads.

 

I look around our lives and metals seem to be the thing that has made the biggest difference between us and the rest of the animal kingdom.

How did this start?

 

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1) somebody found metal meteorite, and found that it's very durable, so naturally started searching for more, from more reliable source (mines).

 

2) Pb has melting temperature 327.5 °C. Tin has 231.93 °C. So if somebody throw accidentally piece of rock which had Pb/Sn, it melted and they found it's pretty usable. Started searching for more such rocks.

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1) somebody found metal meteorite, and found that it's very durable, so naturally started searching for more, from more reliable source (mines).

 

2) Pb has melting temperature 327.5 °C. Tin has 231.93 °C. So if somebody throw accidentally piece of rock which had Pb/Sn, it melted and they found it's pretty usable. Started searching for more such rocks.

Those metals alloy and form pewter. https://en.wikipedia.org/wiki/Pewter

 

Pewter was first used around the beginning of the Bronze Age in the Near East. The earliest piece of pewter found is from an Egyptian tomb from 1450 BC.[3]

 

shows a simple technique of producing copper from malachite. I could imagine this happening by accident and then the process being continually improved.

Edited by Robittybob1
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How did humans discover the use of metals?

 

I don't know but let's see if we can make sense out the clues discovered so far.

 

Stone knives and spears gradually turned into metal knives and metal spear heads.

 

I look around our lives and metals seem to be the thing that has made the biggest difference between us and the rest of the animal kingdom.

How did this start?

 

 

 

This is a great question and you are in agreement with many historians who think that the discovery on how to use metal ores to produce tools and weapons was perhaps the most crucial for any early peoples who would soon become a dominant and successful culture. Especially insofar as warring with other factions. Which, face it, History is mostly comprised of! If you read a bunch of history you inevitably read alot about War! For good or bad, it is what it is.

Here is a nice little article I found on the History of Metallurgy in our World..............http://www.azom.com/article.aspx?ArticleID=6101

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Thank you for interesting video.

 

Here is how they do it in Africa:

 

While watching this video, I wanted to scream "polish metal sheet, bend it, and concentrate Sun light on the one spot..." ;)

Would not need so much wood.

Edited by Sensei
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Looking at the bellows they are driving something of the order of a few litres of air per second into the furnace. (each "cylinder" must have a volume of about 10 litres, something like a third of that is displaced with each pus and one or the other is pushed about each second.)

So there's about 3 litres a second of air run through the furnace containing about 0.6 litres of oxygen.

That's about 0.8 grams of oxygen each second which reacts with about 0.22 grams of carbon

That's something of the order of 0.22 grams of charcoal burning each second releasing about 7KW of heat.

So, adding heat from the sun is just about worthwhile energetically - half a dozen square metres or so of sunlight would add as much heat,

 

I guess what stops them is that they don't have access to big sheets of polished metal but they have lots of manpower and lots of charcoal.

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OK it formed in a star somewhere in the universe before the solar system formed, then it goes through a supernova, then what happens?

A supernova is an exploded star. During a stars death throes, it steadily and exorably burns through all of the elements, beginning with the lightest, like helium and hydrogen, and then steadily moving through the periodic table toward the heavier elements. This of course includes those in the metals group. I believe the process ends with iron and lead.

 

So the star explodes and this is the supernova. Btw there have been ones so big they would have encompassed our entire solar system. The dust of these elements are tossed out into space. Till they become ensnared by gravitational pull of a star. Through a process called accretion they spin and orbit and get more compact and condensed till they are planets in the solar system of that staff that us how their Sun.

 

So that's off the top of my head and is greatly simplified but gives you the basic answer of how those metal ores get into our Earth.

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A supernova is an exploded star. During a stars death throes, it steadily and exorably burns through all of the elements, beginning with the lightest, like helium and hydrogen, and then steadily moving through the periodic table toward the heavier elements. This of course includes those in the metals group. I believe the process ends with iron and lead.

 

So the star explodes and this is the supernova. Btw there have been ones so big they would have encompassed our entire solar system. The dust of these elements are tossed out into space. Till they become ensnared by gravitational pull of a star. Through a process called accretion they spin and orbit and get more compact and condensed till they are planets in the solar system of that staff that us how their Sun.

 

So that's off the top of my head and is greatly simplified but gives you the basic answer of how those metal ores get into our Earth.

OK that's how I think of it too. But the whole image is of crystals of copper ores not big slabs of native copper. Could the Earth's geological processes smelt the ore and make the copper metal pour down into a crack in the rock? (This would have to be a precise temperature range event, i.e. one just enough to keep the copper molten).

My problem is understanding how could the copper molecules coalesce into slabs of native copper?

Edited by Robittybob1
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Looking at the bellows they are driving something of the order of a few litres of air per second into the furnace. (each "cylinder" must have a volume of about 10 litres, something like a third of that is displaced with each pus and one or the other is pushed about each second.)

So there's about 3 litres a second of air run through the furnace containing about 0.6 litres of oxygen.

That's about 0.8 grams of oxygen each second which reacts with about 0.22 grams of carbon

That's something of the order of 0.22 grams of charcoal burning each second releasing about 7KW of heat.

So, adding heat from the sun is just about worthwhile energetically - half a dozen square metres or so of sunlight would add as much heat,

If somebody wants inaccurate data, always might count on you, no doubt. In this you're expert..

I suggest more often using calculator.

There is built-in every Windows since at least Win 3.11..

That's the most used by me computer application..

 

3 L of air, has ~21% Oxygen which is 0.63 L (not 0.6 L),

1 L of Oxygen has density 1.43 g/L,

so 0.63 L * 1.43 g/L = 0.9009 g (not 0.8 g. You used air density instead of just pure Oxygen density (difference between Oxygen density 1.43 g/mL and air 1.29 g/mL is exactly the same as between 0.9/0.8) .. wrong again)

0.9009 g of O2 is 0.02815 mol of O2

If we assume (you did it already) that every single Oxygen is going into reaction with Carbon atom,

C + O2 -> CO2

then there is needed 12 g/mol * 0.02815 mol = 0.33784 g of Carbon needed, not 0.22 grams as you claimed (that's 50% off yours....)

 

Energy density of coal, varies from 24 kJ/g to 35 kJ/g, wood 18 kJ/g

https://en.wikipedia.org/wiki/Energy_density

 

You should make experiment making your own charcoal, then measure energy density, to be able answer how much energy it could release per second in the last stage of our calcs.

You arbitrarily picked up 7 kW, with 0.22 g of C, it's ~ 32 kJ/g energy density... Why do you think so, home-made charcoal will have such energy density? That's nearly energy density of Anthracite..

 

With 24 kJ/g * 0.3378 g = 8107 J (per second released)

With 35 kJ/g * 0.3378 g = 11.8 kJ (per second released)

not yours 7 kW

 

I guess what stops them is that they don't have access to big sheets of polished metal but they have lots of manpower and lots of charcoal.

They don't have coal/charcoal. They had to make it first in the beginning of video at 6 minute.. You have not watched it carefully...

Cutting tree (in area lacking trees, as it's nearly desert) every single time they want to make plough (or something similar from what I can see in the video), is quite large devastation of natural environment..

Edited by Sensei
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Thanks Strange. This bit makes sense: A chemical reaction precipitates metallic copper.

 

Those good at chemistry does this sound right: "Hematite (iron oxide) in the lava oxidized the sulphur, depositing copper. The iron and sulphur were carried away as iron sulphate"?

 

https://uwaterloo.ca/earth-sciences-museum/resources/detailed-rocks-and-minerals-articles/copper

 

 

Keweenawan Copper is associated with lava flows and conglomerates in the Keweenaw Peninsula of Michigan. This deposit is also seen at Mamaise Point, north of Sault Ste Marie. The copper was deposited mainly in conglomerates and flows of basalt, especially near the tops of the flows where the rock had gas bubble holes (vesicles). Hot water, containing sulphur and copper, migrating upwards through the basalt flows and moved across the top of the lava flows where it was sealed by the impermeable barrier of the overlying flow. Hematite (iron oxide) in the lava oxidized the sulphur, depositing copper. The iron and sulphur were carried away as iron sulphate.

Sometimes the copper was deposited in fractures in the rocks. Some masses formed in fractures are of unusual size. The largest of these was a mass found in the Minnesota vein on the Keweenaw Peninsula in 1880. The mass weighed 500 tonnes and was 14 metres thick. These large masses were difficult to mine profitably, so they are still underground!

Copper pebbles and boulders from the Keweenaw Peninsula were moved south by glaciers during the ice age. Copper was used by the native people to make tools. They hammered copper into the desired shape. This hammering made the copper harder, just as a when blacksmith tempers steel. When tempered in this way, knives could be made which were much better than the stone or bone knives which were used before.

Copper was used as early as 15,000 years ago. The metal was found as lumps of native copper and could be easily fashioned into jewellery, tools, or cooking and storage containers. The use of copper increased about 5,500 years ago with the discovery that it could be easily mixed or alloyed with other metals such as tin, zinc or lead. These alloys produced bronze and brass with a variety of useful properties.

Edited by Robittybob1
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If somebody wants inaccurate data, always might count on you, no doubt. In this you're expert..

I suggest more often using calculator.

There is built-in every Windows since at least Win 3.11..

That's the most used by me computer application..

 

3 L of air, has ~21% Oxygen which is 0.63 L (not 0.6 L),

1 L of Oxygen has density 1.43 g/L,

so 0.63 L * 1.43 g/L = 0.9009 g (not 0.8 g. You used air density instead of just pure Oxygen density (difference between Oxygen density 1.43 g/mL and air 1.29 g/mL is exactly the same as between 0.9/0.8) .. wrong again)

0.9009 g of O2 is 0.02815 mol of O2

If we assume (you did it already) that every single Oxygen is going into reaction with Carbon atom,

C + O2 -> CO2

then there is needed 12 g/mol * 0.02815 mol = 0.33784 g of Carbon needed, not 0.22 grams as you claimed (that's 50% off yours....)

 

Energy density of coal, varies from 24 kJ/g to 35 kJ/g, wood 18 kJ/g

https://en.wikipedia.org/wiki/Energy_density

 

You should make experiment making your own charcoal, then measure energy density, to be able answer how much energy it could release per second in the last stage of our calcs.

You arbitrarily picked up 7 kW, with 0.22 g of C, it's ~ 32 kJ/g energy density... Why do you think so, home-made charcoal will have such energy density? That's nearly energy density of Anthracite..

 

With 24 kJ/g * 0.3378 g = 8107 J (per second released)

With 35 kJ/g * 0.3378 g = 11.8 kJ (per second released)

not yours 7 kW

 

 

They don't have coal/charcoal. They had to make it first in the beginning of video at 6 minute.. You have not watched it carefully...

Cutting tree (in area lacking trees, as it's nearly desert) every single time they want to make plough (or something similar from what I can see in the video), is quite large devastation of natural environment..

Throughout the part of the video near the end, they always say that they pause to add ore, flux and charcoal.

They make that from wood, but it's not wood that they use as their smelting fuel. The energy content of wood is utterly irrelevant. Getting hold of the wood is a lot of work, but they have got access to it. Getting hold of polished sheet metal isn't really an option.

"You should make experiment making your own charcoal, then measure energy density, to be able answer how much energy it could release per second in the last stage of our calcs."

I could, but why bother? I already allowed for the fact that charcoal isn't pure carbon: it's just that you didn't notice.

 

Imagine that the charcoal is a mixture of , for example, 90% carbon and 10% "sand" or "ash".

A gram of it would only need as much air to burn as 0.9 grams of pure carbon. (and, equivalently, 1 litre of air would burn 1.11 times as much charcoal as it would pure carbon.

So, by calculating the heat output from the volume of air, rather than the (unknown anyway) mass of fuel, I can avoid the issue of not knowing the carbon content of the charcoal.

There will be an error because of other combustible material in the charcoal, but I'm assuming they are good at their job so that error will be small.

 

What I assumed was that all the oxygen in the air would react. Well, that's a plausible assumption- it's an iron smelting furnace.The conditions are (by design) very strongly reducing.

It's fair to say that not a lot of oxygen will make it through unreacted.

If you want to argue a point about incomplete reactions, the fact that, initially, the charcoal is oxidised only to CO might be more viable thought some of the heat from the burning flare gases will also be retained by the furnace (it's a good design that way)..

 

Regarding the oxygen density, and your claim that "you used air density instead of just pure Oxygen density" No, I didn't- but we can always rely on you for inaccurate data.

 

You have used the value for NTP while I used the value for STP.

Did you see frost on the ground in the video?

If not, why have you assumed that they are at 0 Celsius?

(the number I got was from here)

http://www.engineeringtoolbox.com/gas-density-d_158.html

 

Arguably the value for- lets take a guess at 30o C would be more appropriate, but considering that the volume is pretty much a guess in the first place, we are into your fixation on producing spurious accuracy again.

 

Thanks for pointing out the error in my calculation of the rate of carbon use.

It shows- as you say- that they used roughly half as much again as I thought.

That means that , relatively speaking, the influence of any solar heating they would get was only 2/3 of what I thought.

 

So the metal reflectors, which they don't have, would need to be 50% bigger and thus less practical.

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The smelting of copper was definitely easy compared to the effort to get iron. It seems remarkable that the concept would have been just happened on by chance. Did they go through a series of experimentation to get the method right, looking for the other ores?

 

Years ago I invented the first version of the "Rocket Stove" but the version I made ran that hot it appeared to melt the metals it was made from, so I put it into the too hard basket to market it for home heating for it needed to be built of material like that used by the space shuttle heat shields.

Today the internet is full of versions of the "Rocket Stove" but none come close to the temperatures I was getting as my invention preheated the air.

 

https://www.youtube.com/watch?v=vMMO65b8y6k

 

The other aspect I worked on was too maximise the thermal effect. There appears no need to use bellows if the chimney thermal effect is maximised (keeping it long and insulated).

 

In the Apostol rocket stove there is no attempt to insulate the flue or to preheat the combustion air, and yet he already gets impressive temperatures. It was made of aluminium, so if the flue was insulated it would have definitely melted away in minutes.

 

It was possible to get the air moving through the stove so fast that charcoal lumps would be lifted up the chimney (that was getting scary).

I also experimented with a vacuum cleaner that would blow air into it and made it into a "blast furnace" but it just got too dangerous.

 

At the time I had run experiments to melt various metals and cast iron nearly melted but the ends of the chimney just oxidised and vaporized. (The flue was stainless steel flue pipe)

I am tempted to look at the design again with the intention of smelting iron bloom from ore and charcoal layered as the Africans did without the need for bellows.

Not only that but I think the energy lost in the charcoal making step can be incorporated into the process so it creates its own charcoal (replacing the extra charcoal added later in the video).

Edited by Robittybob1
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On the video you provided he used insulation, but it's inside. Probably some ceramic. Aluminium is just cover.

If he would insulate flue, he also would do it from inside, and ceramic wouldn't so easily transport heat to cover.

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On the video you provided he used insulation, but it's inside. Probably some ceramic. Aluminium is just cover.

If he would insulate flue, he also would do it from inside, and ceramic wouldn't so easily transport heat to cover.

I don't think there was any insulation in the flue, insulation just lining the firebox only. In my case I insulated the outside of the flue. The flue diameter could end up being a more important parameter. They say hot air rises so how would you make it rise faster and with less resistance?

I wonder if you kept the heated air above the flue, then the air column above the fire would be lighter than the cold air pushing the air through the fire. Could this difference in mass generate a pressure differential greater than the effects of the bellows? From what I've seen it would be more than possible. It would be a matter of learning which parts one would want the air to flow through. In a blast furnace is the air going through the carbon and the ore? For that sounds a bit more difficult that just passing it near/around the carbon/ore pile.

 

In the above rocket stove video it doesn't take much wind to make the air flows to go in the opposite direction so I'd say at the top of the flue there needs to be a cowling to stop wind gusts going down the flue.

Edited by Robittybob1
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It was most probably related to magic or witchcraft. I am not sure it was by chance, it may also be the fruit of (early) research.

How do you imagine the research would go? Would they just try out different rocks and see if it was possible to extract some metal? It seems that the step up between copper and iron is a huge step I wonder what made the early humans metallurgists try this?

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How do you imagine the research would go? Would they just try out different rocks and see if it was possible to extract some metal? It seems that the step up between copper and iron is a huge step I wonder what made the early humans metallurgists try this?

Fire must have look like a magical thing or divine or sent by some sort of hell. There must have been a lot of rituals around fire. The ability of fire to transform materials must have been seen as a magical trick.

After that I don't know if they are evidences of some sort but I imagine someone playing with fire putting in it all kind of things and observing the results. Using these results as ornaments first (I don't think copper is strong enough for making any weapon). Maybe gold was discovered rather quickly. Iron must have come much later (see iron age)

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Fire must have look like a magical thing or divine or sent by some sort of hell. There must have been a lot of rituals around fire. The ability of fire to transform materials must have been seen as a magical trick.

After that I don't know if they are evidences of some sort but I imagine someone playing with fire putting in it all kind of things and observing the results. Using these results as ornaments first (I don't think copper is strong enough for making any weapon). Maybe gold was discovered rather quickly. Iron must have come much later (see iron age)

"I imagine someone playing with fire putting in it all kind of things and observing the results" that is what I would have described as chance.

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