The New Method of Smelting

From the year 1887 ‘turn-roasting’, black-copper smelting and refining were all discontinued at the main smelting house in Røros.

Alexander Austnes

 Converter in the Smelting House at Røros. Ca. 1890. Photo: Iver Olsen
Converter in the Smelting House at Røros. Ca. 1890. Photo: Iver Olsen
This was due to the introduction of an entirely new method of production referred to as the Bessemer process.

With the introduction of the Bessemer process, the ore was ‘first roasted’ and copper matte smelted, the then molten copper ore was introduced into a converter. Impurities were removed by forcing air into the molten mass.

Shortly after this new process was started, in June 1888, the smelting house caught fire, however, by November of the same year, a new smelting house was in operation. The new house was now equipped with 2 matte smelting furnaces,
a Bessemer converter and a refining furnace.

 The Smelting House at Røros in 1894. Photo: Iver Olsen
The Smelting House at Røros in 1894. Photo: Iver Olsen
One of the smelting furnaces was of the old type,
built of brick, the other, the so called *American,’
was equipped with a water jacket.

The introduction of the Bessemer system was an enormous improvement in the smelting process at the Røros Copper Works. Extraction of the copper from copper ore using the old 5 step process could take up to one and a half months, the new method reduced the time to, one and a half hours, and, after refining, the end product had a copper content of 99.8%.Further improvements in the production of copper were introduced with the flotation process. The Company’s flotation plant at Storwartz was started up in 1926. The flotation plant produced a copper concentrate of approx. 25% copper. The introduction of the flotation process at Storwartz led to the cessation of primary roasting at the smelting house in Røros.

 Read more about the smelting method

Røros was added to UNESCOs of World Heritage Sites in 1980, refer also to Riksantikvaren, ( Norwegian Inspectorate of Ancient Monuments and Historic Buildings).
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