Reconstructing past smelting processes with modern technologies
An article in English describing the aims, details, and observations of our experiments is now available. Additionally, we use analyical data to discuss how each experiment contributed to the transformation of ore to metal.
The article “Smelting Experiments with Chalcopyrite Ore based on Evidence from the Eastern Alps” was published in the open access-journal Metalla, enjoy reading!
It takes quite a long times until the samples we produced in summer 2018 became data. Soon after the experiments it was clear, which of the four experimental series we want to sample. Then it took over half a year until all the analyses of the more than 100 samples were conducted (believe us, we were not lazy). And a few more months to make sense out of the data and to wrap it up in a nice publication.
But now it is done, since today the results are published! And they were worth all the effort, we think. We were right with our original hypotheses. Well, partly. The copper isotope compostition does not change on the way from the ore to the metal and that’s actually good: we can continue to use copper isotopes to reconstruct the exploitation history of ore depostis using metals produced from their ores. But beware the slag. As soon as slags are involved things are starting to become messy. Or if other material are added. This happened to us when the high temperatured melted the clay of the furnace wall and the tuyères (nozzles from the bellows). This opens up new ways to think about what they could tell us about the smelting process what we cannot know from other methods.
Because we produced really a lot of data and the details of the experiments are exceeding the scope of traditional publications by far, we provide an additional data publication. Beside the tables with all the analytical data you find here a catalogue with detailed information about the samples experiments. And you can also learn how much effort and time it actually takes to analyse copper isotopes.
Enjoy reading!
A little bit more than a year passed since the end of our experiments. In the meantime we were busy in the lab and on our desks. All analyses are finished Recently, the last analyses were made and it is time now to evaluate and interpret the data and finally to publish them.
For the ones who have a nostalgic moment or missed the experiments: They are (fnally) published!
Admittedly, non-German speakers still have to wait, we are sorry. The first one has at least some nice pictures. The second one comes with an English abstract and the captions are in Englisch, too. In the second article, the experimental set-up of each experiment is shown to scale.
The next publications are already in preparation – and this time, they will be in English – promised! And they will also contain the first analytical data. However, it will take several months, until they passed the review process. Once they are published you will see it here first, stay tuned!
Tim Greifelt filmed a whole week during the experiments. Fresh from the cutting room he sent us the rough cut this week. We think, he did a marvellous job!
We immediately started to prepare the sychronisation and hope to present it to you soon. Stay tuned!
I am feeling a little bit happy but also nostalgic at the morning of the experiments’s last day but a tight schedule did not really let us time to think about. A lot of work has still to be done: Three experiments, cleaning up, and packing our stuff.
The consequence is a constant circle of crushing, smelting in the pit or smithing hearth, documentation and crushing again. As we now see the matte from the subsequent experiments that quick one after another it becomes remarkably well visible how the purity of the matte rises with every experiment. Unfortunately we did not achieved a regulus yesterday, neither with the blowpipes nor in the smithing hearth. But you can see in the matte that it is just a matter of repetition. After the experiments (we reached again 1200 °C!) warm words of farewell were spoken.
I will miss the time at the LEA. It’s rare to meet so many interested, competent and nice people at the same time and at the same place. All of us did a great job. I am looking forward to the next project!
A last time the whole crew: S. Klein, T. Rose, M. Hoffman, Rohal, Y. Nienaber, P. Süßer, A. Thiede, P. Castro, E. Hanning, Sam.
The second run of the blow pipes was scheduled for today. So we got togehter once more around the small fire and started our breath acrobatics. Beside a few occurrences of dizzyness, successfully cured with cookies and beverages, everything went smooth. At the end we waited until the slag cake (we called him “Pitu”) was taken out and cooled down. After it we resumed to work on the main task of this week: crushing and smelting.
Today a coach full of tourists visited the quarries and the Terra Volcania. As they were also very interested in our experiments, we took this opportunity to tell them all they wanted to know about the experiments.
After the tourists left us we proceeded with the experiments in the smiting hearth, where we got several nice results. With “Stockbrot” (bread baked on a wooden stick over a camp fire) and Lasange the day finally came to an end.
As it is more than unsure if we will be able to produce copper with our current approaches we decided to conduct experiments with an electric fan in a smithing hearth. The aim is to produce a copper regulus which is well separated from the matte. Of course we did not stopped the other experiment series. While the electric fan made its work we conducted further experiments, this time operating the bellows “Nepalese style” (short strong bursts). Our hope was to reach a higher and more stable temperature. Both of our wishes came true.
In the smithing hearth we managed to produce a beautiful regulus of about 14 g. And in the fire pit A. Thiede and Y. Nienaber achieved temperatures highter than 1200 °C in a superhuman effort, temperatures we never ever reached before in the pit. Additional the liquid melt allowed us to extract several flat slags.
During these experiments, the remaining crew members continued with the crushing to ensure we have enough material to repeat the experiment tomorrow several times and to have a second run with the blowpipes.
At the end of day, we conducted a small experiment to test if a russian coin and malachite will smelt together to brass. Unfortunately a storm arose and we had to abort the experiment.
Well, to be archaeologically correct not the Mayas but the Tarascos… but this doesn’t sound that fancy. Our volunteer from Columbia, P. Castro (living in Mexico at the moment) gave us some insight into her research and showed us how to operate the blowpipes, which were used there for copper ore smelting. In contrast to our bellows, the whole ventilation in this process is done exclusively with the lungs. The results: Five more or less enthusiastic people blowing in step with a metronome (75 bpm) into the fire and a lot of dizzy heads. After a while the mood was like in a Shisa bar. But in the end all of us were happy not to breath synchronous anymore.
Two new faces were welcomed today and as it became a tradition for the newbies, they got the task to help forming the dung balls. Tomorrow we offer a guided tour for the media and the public. Slowly we are getting excited about the question how many will visit us. With the hope that our hair is well set and still a bit dizzy from our breath acrobatics, I wish you a good night.
The final week begins and this time everything is a little bit different. The newbies will arrive later, for today we are on our own. That’s okay because workload is not that heavy this week – we don’t use the shaft furnace but focus on the matte smelting. With reinvigorated forces the slag cake from last week was crushed and prepared to become copper (grinding, grinding, grinding…).
In the evening we had a movie night. Of course we watched a documentation about traditional copper ore smelting in Nepal to get some inspiration for the last experiments. After the movie, all became clear why it don’t worked so far: we missed the most crucial parts, a sacrificed chicken and a heavyly drunken furnace master. Let’s have a look if there is a henhouse around here…
Final sprint before the week end: While the storage rooms were already cleaned up, two more crucible experiments were carried out with the dragon tuyeres. Both of them seem to be quite successful, but for one of the dragon tuyeres the fire of the last experiment was too much. But the possibility to see how the liquid melt drips off from the crucible was more than worth the loss. We will see if it was a good idea to put all of the material at the same time in the crucible in the second experiment. All in all we can be optimistic, I think. Everone of us went with positive feelings into the week end and in the end, the epic battle had a second round.
