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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vi. mining and metallurgical industry.
The blast furnaces constructed in the last twenty or thirty years have a
height of from 16 to 18 meters.
When blast-furnace gas came into use in the thirties as fuel gas for hot-blast
stoves and roasting furnaces, the gas was extracted through one or more openings
in the furnace wall, situated 4 to 5 meters down in the flue (see m in the Figure
below). In the sixties the method of gas extraction was improved: from the
upper part of the shaft, the throat (uppsättningsmålet), a sheet-iron cylinder from
2’5 to 3 meters in height was suspended down the shaft: this cylinder was
termed the gas-collector cylinder. The gas mounted behind this cylinder to openings
in the wall, and from these openings proceeded the gas pipes to the roasting
furnace, hot-blast stove, etc. This arrangement has proved to be extremely
effective. In all open blast furnaces the gas is now extracted in this manner.
However, closed charging devices (slutna uppsättningsmål) have been coming
more and more into use in recent years. About half the blast furnaces now
in work are thus constructed.
Sivedish Blast Furnace from 1850.
Charcoal is always charged into the furnace in fixed quantities; the
charcoal-charge (technically called the lcolsättning), varies according to the size of the
furnace, the normal amount being from 14 to 16 hectoliters.
As early as 1835 35 Swedish blast furnaces were equipped with hot-blast
stoves. All of them were on the Wasseralfinger system (horizontal iron pipes)
and very small, giving a blast temperature of only from 150° to 200° Celsius.
When pig iron began to be made for the Bessemer process, the need of hotter
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