Today, the dragon tuyeres were put in action. Beside their epic look, the bowed shape shall help to direct the air flow into the middle of the crucible and hence to reach a better heat distribution. Food for the dragons came with a freshly prepared load of roasted dung balls. It stank and cracked troughout the experiment but in the end all 80 dung balls were molten in the fire pit. Unfortunately there were small problems with the seam of a bellow which were provisionally solved with a stapler. It was enough for this experiment, but more elaborated repairs are necessary for the upcoming experiments.

While this experiment was done under the supervision of the recently recovered E. Hanning, matte was further ground and copper prills picked under the pavilions. We were very successful, about 30 to 40 g were collected for the isotope analyses. At the end of the day, the documentation was updated and after a short while dinner was ready.

Today was quite relaxed. Several smelting experiments with malachite were conducted but  the day focussed on updating and reworking the documentation. A disagreement between between P. Castro and M. Legault lead to an epic battle but fortunately nobody was hurt.

As there is nothing more to tell today, here is the next recipe from the LEA bakery:

Copper pot made of malachite

Materials:

• High-resolution balance
• Clay crucible
• Fire pit
• Bellows
• Fire tongs
• Hammer
• Chisel
• Bucket

Ingredients:

• 20 g malachite from Kongo
• 2 g charcoal dust
• 1 handful of soil
• 1 bag of charcoal
• 10 l water

Give about 1 g of the charcoal dust in the crucible. Shake the crucible thoroughly to disperse the charcoal dust on the crucible walls. Now add the malachite and put the other 1 g of charcoal dust on top of it. Close the crucible with the soil and put it cautiously in the pre-heated fire pit. Cover the crucible with charcoal and cook it under constant addition of charcoal slowly for about 45 min at 1000 °C. At the same time fill the bucket with water and place it nearby. Use the fire tongs to take the crucible out of the fire pit and cool it down in the water bucket. Open the crucible with hammer and chisel and serve it.

Our unicorn, affectionately dubbed as “Mistefy”, had it’s fire test today. All in all it showed a good performance. Unfortunately we were a bit too ambitious with the addition of branched logs. The bigger pieces of charcoal led to a not so easy addition of the ore and fuel later. While our fronts were roasted by the heat of the furnace, the sun toasted the others sides of our bodies. But with well-approved strategies we survived the day alive and kicking. The sun had at least one advantage: It was hard to differentiate between the heat of the furnace and the heat of the sunshine, taking away the bad feeling of the searing heat on our fronts.

While the bellows were operated, the remaining crew searched for copper prills in the finished experiments to collect them for analyses.

At the end of the day a barbecue was started but innovative methods to light the charcoal were needed due to rising winds. With meat and drink and dexterity games the day finally came to an end.

A new motto seems to arise for this week. It is planned to use the bowed “dragon tuyeres”, we have three Goldsmith among us, and a creative burst of M. Hoffmann and Y. Nienaber led to an unicorn on the furnace front. If this week stays that magic, I won’t be surprised to see epic battles between Good and Bad in the yard of the LEA.

Only three people are new in the crew this week. The other crew members were already here last week or even during both weeks. Accordingly, the preparational work started smooth and everyone fastly found his place. This week we also had the good inention to take more care of a more constant food supply.

 

That’s it, over and out.Experiments for this week are done. In a last effort, the remaining loose material from the shaft furnace was separated in matte, slag and furnace lining, everything was cleand up and the documentation was updated. The slag cake will be crushed and separated next week, to give next week’s newbies an impression in what they got involved.

So only one thing needs to be done:

Thank God it’s Friday!

 

After the tips of several tuyeres were molten yesterday, new ones are needed. Fortunately, a learned potterer is participating this week and made in the in-house workshop new ones in a blink. Active support was given by M. Adam, who freed unforeseen artistic talents. The elaborated decorations with dragon heads or water mills must lead us to success.

Once more we smelted the dung balls today. But before this experiment, the matte smolten from the dung balls last week was smelted again to further enrich the copper. The grinded matte was placed in the crucible while it was intensively heated. As a result, the slag cake was firmly bound to the crucible but makes a good impression at the first glance.

After this experiment, the dung balls were smolten. This experiment also went very well. For the first time a separation of liquid slag on top of the matte was achieved as well as an extraction of the slag.

In the euphoria of victory, it was discussed during dinner whether one should go to “Johnny Schatulle” to celebrate the day but after this very busy day the general consent favoured the bed.

It’s time again: The shaft furnace is fired. All of us get together like everytime to worship this miracle made of fire. Well, not everyone is present yet. In the morning some went to another experiment nearby. It investigates the use and efficiency of roman hand mills for grain (for further information [only in german] click here). In the meanwhile the remaining people heated up the furnace, so we are ready to start as soon as they are back.

With the whole crew the ore was attacked. The long pre-heating of the furnace seemed to pay off. Several times more than 1500 °C were reached and held over several minutes. But we just want to produce copper and not iron, so we had to restrain ourselves and tried to hold the temperature at around 1460 °C.

In the evening we relaxed with star gazing and discussions about Mars and subduction zones. Some of us merely did found to an end but sooner or later fatigue overcame all of us.

Some important terms one might should know:

Slag cake: final product of the smelting procedure in the shaft furnace, in which the molten ore was separated into is different parts.

Matte: copper rich part of the slag cake, intimately mixed with charcoal.

Slag: The silica- and iron rich part of the slag cake, waste product.

Due to forecasted rain, the smelting experimet in the big furnace had to be postponed to Wednesday…

… and at the end of the day there was nothing more to do than stating that rain did not came down.

As there is nothing more to tell than that preparations went on and the marvellous  bakeries of K. Mittelstädt enchanted us, here is the recipe for tomorrow’s cake:

Slag cake:

Ingredients:

• 20 kg roasted copper ore
• 200 kg soft wood

Additional materials:

• Hammer
• Smelting furnace
• Long wooden stick
• Scoop
• Chisel
• Crowbar

Directions:

Preheat the furnace with wood. While the furnace is prehating, crush the roasted ore to a size between hazelnut and pea. Once the furnace is preheated use the scoop to cautiously put the ore on top of the wood. Repeat this precedure until all ore is used. Take care to cover the ore always with wood. From time to time use the long wooden stick to relieve blocking pieces of charcoalin the furnace. After thee to four hours stop the addition of wood and let the fire in the furnace burn down. Not let the furnace cool down for one day. Subsequently the frunace front can be taken down and the charcoal covering the slag cake can be removed. Let the slag cake cool for an additional day and remove it from the furnace with hammer, chisel and crowbar.

The newbies arrived! This week we are 12 people, nearly more than double from last week. This will result in either finishing the daily work extremely fast or a lazy time because there is not enough to do for all of us. A look in the motivated faces shows It will be both, possibly.

Additionally, a camera operator accompany us this week to film the preparational work and the experiments.

This week the work started with the routine developed last week: crushing the roasted ore, chopping the wood, grinding the matte, refresh the furnace lining and building the furnace front. And the release of a new add-on for a well-known RPG during this week inspired our decoration of the furnace front.

To offer enough work for all, E. Hanning and P. Süßer went hunting in the old quarries after grinding stones. With the excellent guidance and surveillance of Sam they made a lot of pray and came back safe and sound.

Author: Philip Süßer

When the flowers summer rain
are overpowered by sulfur smell
When malachites' green blessing
shines through charcoal dust;
Volunteers great in spirit
rush to help were need is be
Whether bustling, whether tired
lead them on oh Roseman

Today the experiments went into their second round. In order to produce pure copper a second smelting step was needed. In preparation for this step, the bottom of the pit we dug yesterday (let’s call him “Big pit”) was covered with a thick layer of charcoal dust, to prevent that the molten material would react with the clay and be lost in the ground.

While this was done, another pit was used to smelt malachite and reduce it to pure copper. This was done in order to find out whether the right conditions could be met in the pits, and also to experiment with different forms of crucibles. The results varied between “very well” over “molten crucibles” to “crucible too large to properly heat up the inside”.

Last but not least the “Big pit” was fired up. The roasted dungballs were put onto a bed of freshly glowing amber and covered with charcoal. The bellows were worked again in order to reach temperatures around 1400 °C. Unfortunately, this time we weren’t able to achieve sufficient separation between matte and slag to quench the top and take of plates of the iron rich melt. Nevertheless, the experience was valuable. After many hours of bellow working and staring into the flames we only had to clean up and go back to our homes. But for some of us, this was only the beginning…