In the past, the center of iron production was not in the Ruhrgebiet, but in the Sauerland and Siegerland regions. This was due to the abundance of forests and ore in these areas, as large quantities of charcoal were needed in addition to the ore to smelt iron ore. In addition, due to the infertile soil and unfavorable weather conditions in this mountainous part of the country, the population had to look for other sources of income than agriculture even back then.
The name 'Rennfeuer' is derived from the word 'zerronnen' or 'rinnen lassen' of the slag. In 1965, Manfred Sönnecken discovered the best-preserved Rennofen Gut Berentrop in the Sauerland region and dated it to the 13th century. The furnace is made of clay and loam and has a hearth diameter of 50 cm and a shaft height of 80 cm, but probably had an original height of around 130-150 cm. The furnace exit, which was closed during the smelting process, was broken open by the ironworkers after smelting to allow the liquid slag to flow out and the 'iron clod', i.e. the lump of iron, to be pulled out.
To prevent the open racing furnace from disintegrating further, this part had to be restored. In the left-hand hearth wall, at a height of 20 cm above the floor, there is a fist-sized wind hole in which there was originally a clay-fired nozzle (clear width 3 cm). Air was blown into the inside of the furnace with the help of a bellows mounted in a trough-shaped depression. The iron ore was extracted from the neighboring open-cast mine and transported to the smelting site. Here the ore was processed by crushing it to the size of nuts and peas and roasting it in a charcoal fire.
The charcoal, which also served as fuel for the furnace, was extracted from the surrounding charcoal kilns. For a single smelting process, around 150 kg of ore and 500 kg of charcoal were used and after around 8-9 hours, an iron slag weighing around 15 kg was obtained, which was still heavily contaminated by charcoal and slag and was then further processed in the forges.
With the help of the town of Neuenrade, the Märkischer Kreis and the Westfalen Office for the Preservation of Monuments, a protective hut was built for the racing furnace in 1983, so that the technical cultural monument is accessible to any interested citizen.
Visits
The racing kiln can be visited at any time or by appointment with Mr. Peter Heymann (02392/507240).