Only a day after Zaka left and we're at another attempt at smelting the copper. I've brought a bucket of water to drop slag into as well, since I'm hoping to scoop that out of the crucible if I can. I've actually got two crucibles to work with this time. One to put into the tray above to cool, and another to attempt to pour into the small ingot cast. I load the first crucible into the furnace, and then put the ingot cast in beside it. After both get up to a healthy yellow glow, I remove a bit of slag from the inside of the crucible with the stone ladle, and drop it into the bucket. Next, I move the crucible up onto the upper shelf, which itself almost looks like it is faintly glowing. I get the second crucible loaded up, and moved into the furnace, and wait for it to get up to a glow as well. While it's going, I end up having to shovel in some new charcoal into the furnace, which I hope doesn't contaminate the copper to badly, but if it does, this is all a test anyway.
After a while, the temperature of the new crucible rises to a hot enough level, and I try to scoop as much of the slag out as I can. Next comes the hard part though, which is pouring the copper into the ingot mold. I've made a small lip on one side of the crucible for pouring, but even with that, maneuvering a heavy crucible on the end of stone tongs near sweltering temperatures isn't easy. I do end up spilling some into the furnace while I attempt to pour it into the ingot cast unfortunately, but overall, the pouring went well. There was still some slag that I had initially missed, which I had to scoop from the surface of the ingot mold after I poured, but over all it went well. The ingot mold wasn't quite full after the one crucible was used, so I took the opportunity to reheat the first crucible and pour enough copper from that to complete the ingot. The only thing left is to stop operating the impeller, and wait for the whole setup to cool down to a reasonable temperature.
As one might expect, the process of cooling took many hours. As much as Zeb and I wanted to work on other projects while waiting for everything to cool down, we were too excited to see the results of the experiment, and would find ourselves checking on it every few minutes, which meant that we barely progressed on any of the other work that needed done, like clearing the plants in the way of the stair construction. By evening however, things had cooled enough that we could safely handle them.
The ingot easily came free from its cast, which I turned over into water to further cool. Thankfully, it wasn't hot enough to cause any boiling. As for the two crucibles, I ended up having to stone shape them in half to free the material inside. One had a copper puck at the bottom, with slag embedded in the top, and the other had some copper holding onto slag in it. I can probably process those again to get the remaining copper if it I want it. I then stone shape the crucibles back together afterwards.
Well, we now have an ingot of copper. It's not particularly big and weighs approximately five pounds. I also put a small little inverted Cu embossing in the cast, so the ingot now has a Cu label on it. I've obviously had a few things I want to try with the copper for a while now, but wanted to wait until I had a semi-pure sample to work with. First, I attempt to stone shape it. Nothing. I can't do it. I figured that might be the case, but still worth a shot. Next, a tectonic sense ping. While not quite the same as pinging a crystal, it does have a distinct lack of noisiness to the ping, and it is very easy for me to tell it is an ingot shape. With some immediate tests done, I decide to put the copper ingot in my workshop, rather than in the massive storage room. I'll probably store more there in the future, but for now, I like the idea of keeping it close.
This opens up all sorts of work that could be done now though. I could make a whole process out of smelting copper, and stockpile a bunch, but actually, as discussed, I don't have a use for it. Instead, I think what I want to try next is attempting to smelt that dark rock that I suspect is an ore of an unidentified metal. Of course, that will require an entirely new process to complete. Unlike the copper, which is in a natural state, this doesn't appear to be a natural metal, instead, it's chemically bound. To get the metal out will require extra work, if it is even in there.
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First, I'll need to really pulverize the rock. For now, I can roughly do it by hand with stone shaping, but if it turns out to be worth it, I'll have to make a rock crusher moving forward. Second, I'll need a flux material to act as a reduction agent for the metal. Thankfully, charcoal actually can work for that, so I'll have to just mix charcoal in as a powder for this test. Sea shells, if they exist, or limestone are more ideal to use generally, but for just figuring out if this is even metal, the charcoal will work fine.
Which means I'll have to take the time to do all that for the test. Thankfully, tomorrow we should be ready for another batch of charcoal to be made, so I can sit and break up stone while I watch the charcoal kiln.
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The charcoal production went well yesterday, and I made a few crucibles with mixes of powdered rock and some charcoal. Today, we'll be unloading the charcoal, and then trying our hand at melting the suspect ore.
Once we got the furnace going, I load the loaded crucibles into the furnace. The melting point of many metals is much higher than the melting point of copper, so once we get the furnace set up, we're going to have to really go hard on the crank for the impeller. Zeb and I will probably need to trade off with the hope of getting the temperature to a light yellow.
Once the crucibles get to an orange-yellow glow, and they don't seem to be heating more, Zeb and I have to start trading off on operating the crank as fast as we can. We only keep the frantic pace up for about twenty minutes before we are both so exhausted we can't keep turning the crank at that pace any longer. The crucibles are glowing a nice yellow, so I'm hoping they're hot enough to melt any potential metals out of the suspect ore. Although I won't know until tomorrow, since it's going to take a long while for the whole furnace to cool down so I can check the crucibles. After I rest for a short bit, I move the crucibles up into the cooling tray up above the furnace before leaving it to cool.
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Well, results are mixed. On one hand, we did recover a bit of dull silvery metal in each of the crucibles. The downside is that, for the almost two pounds of rock in each crucible, we only recovered about a quarter of a pound of metal from each. Which means, of whatever this metal is, it will take a lot of ore to recover a useable amount of metal. Plus we nearly exhausted ourselves to make this small amount. On the other hand, depending on the properties of the material, there is a very large amount of the ore, so it could be worth coming up with a solution to these problems.
To determine that though, I'll actually need to do some testing on the metal to determine if it is even worth gathering. Since I have a few puck shaped pieces of the metal from the crucibles, I suppose that is what I'll work with.
The first property I notice through simply impacting the puck against my desk is that the metal is somewhat brittle, breaking along clear sheer lines. The next test reveals that it's harder than copper, since it is able to scratch copper, but it can't be scratched by it. It's less hard than stone still however. It also breaks when I try to bend it. From these tests, I'm suspecting that it's probably majority iron, or more specifically right now, a pig iron.
Pig irons are rich in carbon, which leads to them being very brittle and hard, and not very useful. Which means it isn't very useful in its current form. The unfortunate aspect of it being pig iron is that to make it useful, I'd need to remove carbon from the alloy. Which is a whole extra process. That is, if it even is pig iron. If it's something else, then all that work might not be worth it. On the other hand, if it is iron, then the value of having access to steel is almost immeasurable, although the process of actually getting to a reasonable amount of steel would be a whole endeavor of it's own.
For now, I'll just set the pucks of metal aside. As much as I would like to pursue the whole thing right now, I do have other things I can work on before that point which have a higher chance of being viable.