Full resolution (JPEG) - On this page / på denna sida - VI. Mining and Metallurgical Industry. General Survey. By C. Sahlin - 2. Iron and Steel Industry. By J. A. Leffler
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the manufacture of wrought iron.
281
blast became urgent. In order to meet this need, hot-blast stoves were
constructed with vertical pipes, on the Gjers system, and also of improved
Wasseral-finger type. The latter are now very common; with them a constant
temperature of 400° and an occasional temperature of 500" Celsius can easily be
obtained. "Regenerative" stoves are used only at Degerhamn, Domnarvet,
Björneborg, and Avesta. The blast pressure (for charcoal) is usually from 50 to 100
millimeters of quicksilver.
Drying apparatus for charcoal came into use in the seventies, but are now
no longer employed.
Open Blast Furnace.
Blast Furnaces with Charging Device.
Charleville System. Tholander System.
The pig iron made obviously differs in quality according to the purpose for
which it is to be employed.
As has been previously mentioned, the cast iron needed for home
requirements is imported; only a small quantity is made in Sweden.
Owing to the complete roasting of the ores and the freedom of the charcoal
from sulphur, the Swedish pig-iron is very free from sulphur; the sulphur
contained in it seldom amounts to 0’03 %, it generally keeps below 0’02 %, and it
frequently descends to about O’oi % and under.
The phosphorus-content is also, as a rule, low; but, as in Sweden there is a
plentiful supply of ores rich in phosphorus as well as ores poor in phosphorus,
pig iron may be made at pleasure with the most varying phosphorus-contents,
ranging from the iron rich in phosphorus needed for the basic Bessemer process,
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