I’m sure it is, but there are blood centers all over the country testing hematocrit as a rough indicator on a regular basis. I have erythrocytosis and the doctors only want a full analysis once a year, the rest of the time they’re just concerned with spikes or dips in the level. And the labs and testing equipment manufacturers certainly want everyone to use the more expensive testing. I’m sure there are far more centrifuges like thisthan there are blood analysis machines. I started making one myself after seeing this post in an old thread on the subject. My stated reason was to save time by not going to down to the blood center on a monthly basis, but actually I just wanted something to tinker with. However, I’m not going to say a simple hematocrit level test is a very valuable diagnostic tool, nobody should be counting on that result for diagnosis.
So I can’t just fire up my charcoal grill, open a vein, and make a sword?
There goes my weekend plans.
Being Vetinari, surely he used the blood of the animals he tended to?
The blood center I go to doesn’t use a centrifuge. Instead, they capillate the blood into a little thing that looks sort of like a microscope slide, slip it into a machine, and about a second later the machine beeps and displays a number. I think it’s actually RBC it’s measuring, not hematocrit, but whatever it is, it’s even easier than the centrifuge.
I assume it’s an optical device and can actually count the cells which is going to be a much better measurement than the hematocrit as a percentage. I don’t know what type of device it is, but blood centers have the advantage that they are not testing labs and can use less expensive devices and procedures to perform screening tests.
ETA: And this is not really off topic, you can make the blood sword process slightly more efficient if you use simple tests to weed out anemic enemies and just use them for dog food.
This seems like way too much work for an evil overlord. Seeing as all iron atoms are identical you may as well just slaughter the 1000 people, drain their blood into vats inside your foundry and then tell people your new sword is made from blood.
No one will ever be able to tell the difference.
Even better and faster, you could take them prisoners and feed them excess iron until they die.
Scylla’s comments notwithstanding, I am not sure why taking the requisite amount of blood, drying it to remove all water, heating it in air to >1500F to burn off all carbon, phosphorus, sulfur, nitrogen, and other trace elements, then mixing the resulting ash (hopefully mostly iron oxide at this point) with limestone and enough charcoal, give it a healthy blast of heated (perhaps oxygen enriched) air would not produce a high carbon cast iron (and a fair amount of slag). Said cast iron could then be melted and blown again with air (aka the Bessemer process) to make a low-carbon steel.
You might be able to take the blood-ash, mix it with charcoal and blow it with a lower volume air to make a sponge iron, take this sponge iron and beat it with hammers while red hot (like the Japanese process). I am not sure what contaminates would exist in the blood-ash (mostly calcium, I’d expect) that would be removed by the limestone flux in the blast furnace process but would remain with the sponge-iron process, but the resulting wrought iron might be equal to (or superior, particularly if you consider the psychological effect) to the wrought iron weapons used during the “iron age”.
I’m happy to stand corrected on this, as I am not a metallurgist, and my knowledge on this subject only comes from reading a few articles on basic smelting for this thread, but I can pretty much guarrantee that what you’ve just said wont work. 1,500 degrees is way to hot for your initial run. You would already have burned off all your iron into ferric oxide. Remember, you can burn steel wool.
Again, I don’t think everybody just how truly difficult and finicky this process is. In your example you are already applying your fluxes after you’ve burned off your iron.
Iron ores are chemically very different from the heme molecules you’ll be working with. Regular ores which are well understood and which we have thousands of years of practice with are still notoriously variable. Each type of ore requires it’s own smelting recipe which varies even further based on impurities and iron content. So much heat for so long, such and such fluxes applied at such and such a time, pour off of slag, more heat, more fluxes, adding of carbon in such and such a form, reintroduction of oxygen whether by chemical or air at such and such a time.
This shit is going to a lot more difficult than you think.
Scylla, you are very close on all of this but you have a couple of things wrong about the complexity of smelting iron. It did not take thousands of years of refinement of the process to make decent iron. It did take a long time to refine the process of steel making though. Let’s stick to iron initially. A bloomery is a simple means of producing low carbon iron. Any differences between the composition of blood and common iron ores will not matter in a bloomery. The blood will not contain enough silicates to make good wrought iron, these would have to be added in. Bloomeries do not need flux, they operate at a lower temperature than blast furnaces which decreases the uptake of carbon in the iron. With refinement and care a bloomery can produce steel, but we’ll assume we’d waste a lot of blood working that out and we don’t want to run out of enemies before we get it all sorted out.
You also don’t burn up iron. It starts as iron oxide or other compounds that are reduced by heat and carbon monoxide. The carbon fuel has to be carefully controlled to prevent excess carbon from combining with iron, that would produce brittle cast iron, but that process won’t change because you are using blood instead of common ore.
If you wanted to use the iron to make steel you could have a problem with impurities in your iron if you used the crucible steel, finery steel, or original Bessemer process. The original Bessemer process had many problems because it used cold air which is nitrogen rich and that doesn’t always effectively convert iron to steel with certain impurities. Finery steel and crucible steel require very pure iron that you probably won’t have. But you could still make steel using a reverberatory furnace if you wanted to, or you could also just use an electric arc and use pure oxygen to guarantee the conversion, which would be a conversion to pure iron, and then you’d add carbon to produce steel. You could also start with carbon rich iron as produced in a blast furnace for these methods. Blast furnaces are a little more difficult to build properly but require much less control of the burn because you don’t care if you end up with carbon rich iron. Fluxing is not that critical either, you have to build your blast furnace out of the proper material for whatever the constitution of blood actually is, but there are only a few choices and the proper one can be determined with simple testing.
If you are going to bother slaughtering all those enemies, and drying all that blood then the smelting and steel making processes won’t seem very difficult in comparison. And you don’t need steel, a wrought iron sword will be pretty close to the characteristics of a steel broadsword. The lower ductility of the iron will make the sword somewhat heavier, and it’s edges won’t be as hard, but it will have tensile strength nearly equivalent to steel.
Mythbusters?
Government grant?
That’s the idea. Burn the iron to iron oxide, then reduce the iron oxide to elemental iron (or pig iron in the blast furnace).
It really isn’t that difficult or finicky, if you understand the process. Iron oxide (any of the various oxides of iron) will be reduced to elemental iron in an atmosphere that has a very high CO to CO2 ratio. It takes a large amount of free carbon to produce a high enough CO:CO2 ratio to reduce FeO to elemental Fe, hence the need for a lot of charcoal (or metallurgical coke, but that generally introduces sulfur, which can cause problems later). High temperatures increase the rate of the reactions.
I am pretty sure I know what I am talking about.
What you are describing is important if you want to fine-tune the process to produce a medium-carbon carbon steel, low in impurities that are introduced by either the ore, flux, or coke, but if you have a pure iron oxide (burnt blood meal) and a pure carbon source (charcoal), it really isn’t difficult once you can reach the needed temperatures. While cast iron will melt at ~2400F, to melt low carbon steel, you’ll need 2750F or better. It is difficult to reach and maintain 2750F using a bellows fired charcoal fire, but you can get to 2400, if you try really hard. If you can make do with sponge iron (which you can turn into wrought iron), you really don’t need more than 1800-2000F.
Iron atoms are iron atoms. If you heat organic iron-containing molecules in an excess of oxygen and the organic molecules will break down. Any iron will be oxidized to iron oxide. Most of the other elements will turn into gaseous oxides. The iron oxide can then be reduced to elemental iron in a high CO atmosphere. This really only takes around 1800F, but if you want the limestone to flux out any calcium and silicon, you have to get quite a bit higher. If you want to melt low-carbon steel, you really have a problem if you want to do it with a charcoal fire, which is why most (essentially all) steel mills today use an electric arc furnace.
ETA: What TriPolar said.
Not quite. There’s such things as isotopes. Someone could do an isotopic analysis of the iron in your sword and determine it came from ore from a certain mine, rather than blood.
Yeah, you’ll burn the iron, but that isn’t actually a problem, because unlike the oxides of carbon and hydrogen, iron oxide is a solid. Oh, you’ll probably still lose some up your chimney in small soot particles, but even that can be reclaimed to some extent, and it won’t be most of it.
I still say your slipshod smelting techniques are going to yield a shitty and cruddy broadsword. Don’t come crying to me when some asshole with a Kmart sword cleaves your crappy blood blade in two and chops off your head.
You’ll be all like “hey, maybe we should have listened to Scylla and taken this more seriously. If we had chelated the iron out of the blood into urine and then precipitated it with acid we would have had pure high quality iron to start with, and maybe we wouldn’t all be lying here with our swords broken and heads cut off”
I love The Straight Dope. So very, very much 