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vi. mining and metallurgical industry.
to iron containing only about O’oi % of phosphorus. A large number of ores in
Central Sweden, for instance certain Dannemora ores, etc., and also certain
concentrated ores, contain merely from one to two thousandth per cent of phosphorus.
When smelted with charcoal, practically free from phosphorus, these ores yield a
pig-iron with from 0-oi2 to 0-oi6 of phosphorus. The fact is that the pig-iron
absorbs from the charcoal a certain amount of phosphorus, as a rule from O’oio
to O’ois, occasionally less (the amount of phosphorus in charcoal made in kilns
from barked and floated pine-wood is extremely low).
Pig-iron intended for Bessemer and acid Siemens-Martin usually contain from
0*020 to 0*030 % of phosphorus.
Several magnetite ores in the midlands of Sweden contain from 1 to 5 % of
manganese and a very trifling amount of phosphorus; they yield a pig-iron of
very superior quality, especially for the Bessemer process.
In 1865 spiegeleisen with from 12 to 18 % of manganese began to be worked
at Schisshyttan. The fuel was a mixture of coke and charcoal and the charge
a magnetic iron ore, containing knebelite.
’ The consumption of charcoal per ton of pig-iron in the Swedish blast furnaces
varies considerably according to the quality of the charcoal and the ores, and
according to the kind of iron it is desired to produce. At present it is from
45 to 75 hectoliters, but the average consumption for the whole country, not
counting the iron made with coke, was in 1913, according to the official
statistics, 57-7 hectoliters. In 1912, 1911, 1910, 1909, and 1908 the
consumption was 59’2, 61’2, 62’8, 63’*, and 63’6 respectively. Thus the consumption
of coal is decreasing, thanks to the improved construction and operation of
the blast furnaces.
Manufacture of Pig Iron by Electricity.
The following figures give the quantities of iron made in Sweden
in electric blast-furnaces (see Table 53):
Year .... 1908 1909 1910 1911 1912 1913
Tons .... 122 302 890 5786 17561 31916
At the beginning of the year 1914 there were 5 electric blast furnaces
at work in Sweden (one at Trollhättan, one at Domnarvet, three at
Hagfors). Besides this, one was projected to be built at Söderfors and two at
Hagfors. Each of these furnaces have a power of from 2 000 to 3 000
kilowatts.
The idea of producing pig iron by the reduction of iron ore in electric
furnace is not a novel one in Sweden. That this idea should arise in
Sweden was quite in the natural course of things: no country possesses
the necessary conditions — a plentiful supply of comparatively cheap
water-power and rich pure ores — in a higher measure than does Sweden.
Moreover, the increasing difficulty of obtaining charcoal at reasonable
rates in conjunction with great developments in electricity brought
matters to a head, and people addressed themselves in earnest to tackle the
knotty problem.
The engineers A. Grönwall, A. Lindblad, and O. Stålhane at Ludvika formed
a company under the name of Aktiebolaget Elektrometall, one of the objects of
which was to construct an electric furnace suitable for the reduction of iron
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