Full resolution (JPEG) - On this page / på denna sida - Second part - IX. Mining Industry and Metal Production - 2. The Iron and Steel Industry. By the late Prof. J. G. Wiborgh - Wrought iron
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728- ix. mining industry and metal production op sweden.
Walloon forging in this form is called whole-tcalloon, but
sometimes the pig iron is used in smaller pieces called »galtar» (»boars») in
melting- and »räck»- hearths of the same form as Lancashire hearths.
The forging is then called half-tcalloon. The consumption of coal is
here much less, and the weekly output greater.
Lancashire forging. In the
decennium 1821/30, a very essential
improvement was made in the
construction of forging hearths in
England. Instead of the open
hearth formerly used, the melting
chamber itself was surrounded by
cast iron slabs with an arch of
brick as a roof, so that the hearth
was closed and provided with
only one working port, the bottom
of the hearth was kept cool by
means of a box containing water
placed under it, and finally there
was placed immediately behind
the hearth a heating chamber for
the pig iron, which was
preheated by the escaping gases
issuing from the hearth before
put into the hearth to be melted.
By means of these
arrangements an enormous amount of
charcoal and time were saved above
what was required in the Grerman
or Walloon hearths. Mr G. Ekman,
very skilled in the Swedish
process of iron making, and warmly interested in its development, made several
journeys to England to study the method of forging in these new hearths,
imported workmen from there, and had trials made with these hearths,
first at the Söderfors works in 1831, and afterwards on a larger scale at
the Liljendal works in 1836, and from that time this forging, which is
called Lancashire forging, may be considered introduced into this country.
The hearth has sometimes one, hut more usually two tuyeres, which are then
placed on opposite sides of the hearth. These tuyeres incline about 12* against
the bottom of the hearth and are kept cool with water. The blast pressure is
40 to 60 millimeters mercury. Nowadays only hot blast is used, which is
obtained from a little pipe-stove heated by the gases escaping from the hearth.
The figure on page 729 shows a Swedish Lancashire hearth with two tuyeres.
The refining is done in the following manner: — For each charge are used
100 to 120 kilograms of pig iron cast in small flat pieces (called »galtar»),
which have previously been heated in the heating chamber
Q. Ekman.
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