20th December 2017, 10:10 PM | #61 | |
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A few comments on smelting etc.: "Smelting" is the conversion of ore to metal. For iron, this is typically done by using carbon to bond to the oxygen in an iron oxide, giving CO or CO2 and metallic iron. For a metallic meteoric, there is no need for smelting, because it's already metallic. For any ore, you smelt, by definition, to obtain metal. For iron, the temperature required is well below the melting point of iron, and the chemistry can be made to happen in the solid state, giving a bloom. The is some conflation of "smelting" and "melting" in non-technical usage. You can melt with smelting (just start with metal instead of ore) and smelt without melting (as possible with iron). When an ore is heated to remove moisture, the process is "roasting", not smelting. Some ores (like limonite) are hydrated, and some are not. Roasting can also be used to make other changes in the ore, such as converting sulphides to oxides. The difference between smelting and roasting is that smelting produces metal and roasting produces a different type of ore. When limonite is roasted, it's converted to haematite, which is then smelting as usual. The usual early traditional method to smelt limonite (e.g., bog iron) was to roast and then smelt in a bloomery furnace. For details of the chemistry of smelting and roasting: https://www.tf.uni-kiel.de/matwis/am...ne/ra_2_2.html or the version with frames if you want to navigate to elsewhere in the document: https://www.tf.uni-kiel.de/matwis/amat/iss/index.html I haven't heard of limonite with significant amounts of nickel. The common high-nickel iron ore is laterite. Jambon gives some data for nickel and cobalt content of various laterites. Other refs: Comelli et al. 2016: https://doi.org/10.1111/maps.12664 Jambon: https://doi.org/10.1016/j.jas.2017.09.008 Ströbele et al., 2016: F. Ströbele, K. Broschat, C. Koeberl, J. Zipfel, H. Hassan, Ch Eckmann The iron objects of tutanchamun. Metalla Archäometrie und Denkmalpflege 2016, Göttingen Sonderheft, 8 (2016), pp. 186-189 |
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20th December 2017, 11:45 PM | #62 |
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I spoke too soon.
Good stuff Timo, and clearly more advanced than my own knowledge, especially so in your use of terminology, my own terminology is that used by people who actually work with the materials. For instance, there used to be a gentleman named Mike Peterson who did a smelt once a year. Mike has passed on now but he lived on the South Coast of NSW. In technical terms he probably did not really smelt, what he did was to collect a lot of various kinds of iron and steel, stack with charcoal and produce a bloom. Or maybe Mike did "melt with smelting", as you have noted. I have a piece of one of the blooms he produced, and have worked with this material. It requires quite gentle initial welding, not dissimilar to welding meteorite. It makes very good blades. My understanding is that limonite comes in various forms and that the solid forms of limonite were forge worked in early times by smiths in sub-Saharan Africa. I actually have a few pieces of limonite, identified as such by a metallurgist, I picked it up at Bungonia and had it for years before I knew what it was. I have not worked with it, but from the look and feel of it, it seems as if it could be worked in a forge. Yes, I understand that limonite was worked in later times by heating to remove moisture, and then to use smelting, but in early times my understanding was that it was worked in the forge by gradually increasing temperatures, first removing the moisture then welding and folding. Yes when limonite does carry nickel, the content is quite low, I think something like 1%-2% ? I know nothing about laterite ores, I've heard the name, but only in connection with soil and with building materials. Last edited by A. G. Maisey; 21st December 2017 at 12:06 AM. |
21st December 2017, 12:39 AM | #63 | ||
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The goal is to carburise the iron to produce steel, and done right it can make excellent steel. The diffusion of the carbon into the iron is the same as what happens when you make steel directly in a bloomery. You don't want it to melt, since you want high-carbon steel, not cast iron, so you get a bloom. I guess (but it's only a guess) that the bloom would be much cleaner than the bloom from a bloomery smelter, since if you just put in iron and charcoal, you should get a bloom full of slag. Steel made this way is called oroshigane by the Japanese, and it's still done for swordmaking. For those interested, video showing this kind of thing: https://www.youtube.com/watch?v=n5Zyf8svLKI I've heard of people doing similar things with forge scale, which is smelting (since it's an oxide). Quote:
[A pause, to go away and learn more.] OK, the deal with laterites is that "laterite" is a very broad category, and includes rocks that are iron ores and rocks that aren't iron ores. If they are iron ores, the iron is usually in the form of limonite. 70% of laterites contain limonite. Anatolian laterites have a Nickel:Iron ratio of about 1:30. If you made nickel-iron from them with 100% efficiency, you'd get about 3-4% nickel in the iron. Some laterites have more nickel than that, which is why (a) 8% (rather than 4%) is often considered a good rule of thumb to distinguish between ancient smelted nickel-iron and meteoric iron, and (b) people look at the nickel:cobalt ratio because that tends to be different for terrestrial vs meteoric (and Jambon has some nice graphs showing this (but his data doesn't include Anatolian ores)). |
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21st December 2017, 03:05 AM | #64 |
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This is very interesting technical information Timo, it is something that for the most part I do not know, in fact something I have not needed to know, my knowledge in this area deals with forge work, and I --- and I believe most other people involved with forge work --- tend to look at all the processes that produce the material with which we work, as "smelting". Obviously technically incorrect.
I had intended to stop posting to this thread, but your posts gave it a new life, well, at least for me they did. However we've still got King Tut's dagger sitting in front of us, and if we can now accept that it is indeed meteoritic material, which it must be if the nickel content is as high as it is reported to be, then we really only have one question:- prior to 1323BC who had the technology that could forge weld iron or could cast iron? welding depends on heat and pressure, but in the absence of a massive power hammer, the heat needed to weld iron is around 2500F - 2600F nickel will weld at a slightly lower temperature than iron casting depends upon having liquid metal, iron will melt at about 2800F Prior to 1323BC, when King Tutankhamen died, what people, anywhere in the world, had the technology that would provide temperatures in excess of 2500F? If that question can be answered we will know where the King Tut dagger came from, if it cannot be answered all we can do is to speculate. --- or maybe Erik von Daniken had the answer after all???? |
21st December 2017, 04:06 AM | #65 |
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I am fascinated that this thread got this technical and went on so long. Great info, and it seems now that it has come full circle.
Thank you for sharing your knowledge. Alan, I especially thank you for your forging insights. In fact, I thank every one of you for your insights and thoughts. |
21st December 2017, 10:06 AM | #66 | |
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However, as long as all we have is very little factual evidence, any theory might be the valid one. In this context, maybe Roland's hypothesis may be closer to reality than we will ever know... Meanwhile... MERRY CHRISTMAS! |
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22nd December 2017, 03:36 AM | #67 | ||
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As you noted, while it takes high temperatures to forge weld iron, it's otherwise low-tech: Quote:
Casting (low-carbon) iron or steel is much more technologically demanding, and I know of nobody doing it before the Industrial Evolution. The Chinese were casting cast iron about 2000 years ago, but "cast iron" has a quite low melting point (about 1200C/2200F) since it's a saturated carbon solution (typically 3%-4% carbon). Iron forging/welding technology might have preceding iron smelting technology. First, it allows small pieces of meteoric or telluric iron (native iron, i.e., naturally occurring metallic iron of terrestrial origin) to be used to make larger objects than would be possible without welding. Second, it appears that there was occasional accidental smelting of iron in the copper industry, when iron oxide was used a flux in copper smelting (and temperature got a little higher than needed for copper smelting). So there was motivation for forge welding iron. Forge welding of copper alloys and gold was already known, so the basic idea was there. Judging by the history of the techniques, forge welding iron is much easier than casting (low carbon) iron. But "Who?" is a difficult question to answer. |
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22nd December 2017, 06:27 AM | #68 |
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Yes, correct Timo.
I threw the idea of casting into the mix because of two things:- some suggestions that it might have been cast as a continuation of bronze casting, and the fact that I cannot find any authoritative opinions of the KT dagger being forged. On my monitor I cannot see any evidence of it being forged, but I'm certain that in the hand that evidence would be obvious. What I'd like to see is somebody who has handled it and who knows exactly what he is looking at to have published that it is forged. I personally think it was. There seems to be good evidence that iron working technology appeared in India before anywhere else. The Vedic Peoples had Aryan roots, the Hittites and Mitanni were also from Aryan roots.They worshipped the same Gods. I wonder if there was contact between the New Hittite Kingdom and the Vedic Peoples of India? It seems that the formation of the New Hittite Kingdom coincides with the beginning of iron working technology in India. We know that in the early 17th century BC Indo-Aryans were moving from the East to the west and through the Middle East. I tend to think that when the requisite research has been carried out, and from my enquiries it appears to be something that is still ongoing with as yet no definite conclusions, we might find that Hittite iron technology has its roots in Indo-Vedic or Indo-Aryan culture, which in effect can push the beginning of Hittite iron age technology back to 1500BC, which just happens to coincide with the time by which the Hittites had developed viable iron weapons. My personal opinion remains the same as it has been from the beginning of this thread, and in fact for a very long time before this thread began, and that is that the King Tut Dagger was a product of Hittite technology. Incidentally, I have finished reading the papers that were so generously bestowed upon me, and I now have no doubt at all that the material of the King Tut Dagger is of meteoritic origin. Facts seem to have a half-life of about 45 years (Arbesman) so this meteoritic origin might not be a fact forever, but as at right now it seems to be a pretty good imitation of a fact. |
2nd March 2022, 03:42 PM | #69 |
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At the risk of resurrecting a zombie thread, I want to post this new article about Tutankhamun's dagger. Seemed to make more sense to add it to the robust discussion of this thread, rather than create a new one. I've always been fascinated with this knife, and while the newer findings simply support past speculation, I enjoy learning more about it. I hope some of you do, too
https://www.yahoo.com/entertainment/...193343647.html |
5th March 2022, 04:09 PM | #70 |
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I'm not sure why members are always sheepish about resurrecting old threads. If there is new information that os pertinent to the discussion it seems to me exactly what you should do. So i would say it does indeed make more sense to add to this thread rather than begin another.
I'm not sure how much new info this particular article has added. I already posted the bit about the iron dagger gift to KT's grandfather Amenhotep III, suggesting it might in fact be the same dagger. The article does talk about Widmanstätten pattern made visible through X-ray and points out that this means the blade was forged at temperatures lower than general steel forging points. The photos in the article don't show that very well, but there are some better photos in this article linked below. If indeed these are Widmanstätten patterns that does indeed seem to point to meteoric origin. https://arstechnica.com/science/2022...m-a-meteorite/ |
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