Author: Philip Süßer
The wheather Gods have been kind to us. Due to the calm wind and generous irrigation of the area surrounding the furnace using the facility-built in rainwater cistern, we were able to proceed firing up the experiment. Before heating up the Mitterberg-inspired furnace everyone got the chance to familiarize themselves with operating the bellows and working in pairs to get a constant air flow into the fire. As soon as the furnace reached a temperature of about 1000 °C practice time was over and the bellows and the newly achieved skills were put into action.
After reaching 1200°C using the bellows, the furnace was filled to the top with firewood and a short while after, the first batch of ore was introduced into the fire and covered again with wood. Subesquently more wood and ore were introduced accompanied by regularly compressing the material already in the furnace. To make sure that the last batch of ore could sufficiently smelt, the bellows were operated for two more hours before finally letting the fire burn down.
In constrast to our previous experiment, we managed to reach temperatures exceeding 1500 °C. Consequently, parts of the inner furnace lining started to melt and caused blockages in the air supply. Keeping the tuyeres free meant extra work for our furnace operator E. Hanning from a relatively early stage of the smelt on.
But not only E. Hanning was running on high temperatures. With a cosy warmth of 40 °C outside, also the bellow operators were getting their share of a good roasting. But plenty to drink and good sunprotection, as well as frequent exchange of the operators were the first priority, the effects of the heat were kept at bay.
To see the fruits of our labor, patience is needed. The furnace is still very hot and will take at least a day to be cooled down enough before it is possible to tear down the front wall and have our freshly produced slag-cake brought to the surface.
