IMPROVEMENTS IN AND IN CONNECTION WITH THE CASTING OF PIG METAL
Year: 1882

page_text: LETTERS PATENT to John Thomson King of Liverpool in th County of
Lancaster Patent Agent for an Invention of IMPROVEMENTS IN AND IN
CONNECTION WITH THE CASTING OF PIG METAL communicated to him from
abroad by George Alexander Leishman of Pittsburgh, Pennsylvania United
States of America
•
PROVISIONAL SPECIFICATION left by the said John Thomson King at the
Office of the Commissioners of Patents on the 18th October 1882.
"
JOHN THOMSON KING of Liverpool in the County of Lancaster Patent Agent,
IMPROVEMENTS IN AND IN CONNECTION WITH THE CASTING OF PIG METAL
[communicated to him from abroad by George Alexander Leishman of Pittsburgh,
Pennsylvania United States of America]
My invention relates to the casting of pig metal produced from iron ore in blast
furnaces, and to the casting floor or bed on which the metal is cast.
<<
The usual floor or bed employed at blast furnaces is formed of silicious sand in
which the main trough leading from the furnace, and the moulds composed of the
SOWS "and the "pigs" are moulded. The molten metal runs from the furnace
down the trough and into the sows, and from them into the pigs, the pig metal so
cast being covered with sand to permit the workmen to walk over it in "breaking
up" the pigs, and being allowed to lay there until sufficiently set and cooled for
removal. It is found that in running over the sand, and cooling the molten
metal burns into and takes up part of the sand, so that a crust of about one-half
inch of combined metal and sand is formed around the pig. An allowance for
this sand and that adhering to the metal is necessarily made in selling, the usual
allowance being about twenty-eight pounds to the ton The sand so taken up,
of course increases the proportion of silica in the metal, which is very objectionable
in certain classes of pig metal, such as Bessemer or foundry pig.
Pig inetal has also been cast in cast iron moulds arranged on the casting floor,
but these moulds are going out of use in large casting floors, as they chill or
impart a temper to the outer surface of the pigs, and they absorb the heat from
the metal, and require too much time for cooling. The upper surface of the
C

page_text: metal would also burn into the sand thrown over it, and a crust of combined
metal and sand be formed on the top of the pigs.
As a substitute for the silicious sand, the casting floor or bed has been formed of
furnace slag reduced to the necessary degree of fineness; but the slag, being a flux
formed principally of silicate of lime had no chemical action on the pig metal cast
in it, and did not wholly overcome the objections to the ordinary sand; as it
adhered to the pig metal and necessarily increased the proportion of silica carried
into the furnace or cupola.
The objects of my invention are:-
First. To overcome those objections found in the silicious sand, slag, or chill
casting floors and form a pig clean and free from silica adhering to it.
Second. To remove the phosphorous from the metal or reduce the proportion
contained therein.
Third. To form the grain of the metal more open, and thus adapt the ordinary
forge metal for foundry purposes, and also to improve the quality of the metal.in
other particulars
Now my invention consists First. In casting the pig metal in dolomite or
equivalent basic calcareous sand and covering the pig metal so cast with such sand,
thus entirely enveloping or surrounding the metal with it and continuing the
process or treatment during the cooling of the metal.
Second. In a casting floor or bed for casting the pig metal formed of dolomite
sand or other sand composed of equivalent basic calcareous material, so that the
pig metal is cast clean and free from silicious sand, and is dephosphorized in
passing over the dolomite sand and in cooling in the moulds formed of it, whereby
a stronger and more open, or porous and homogeneous metal is obtained.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Thomson King in the Great, Seal Patent Office on the
18th April 1883.
JOHN THOMSON, KING of Liverpool in the County, of Lancaster, Patent Agent
"IMPROVEMENTS IN AND IN CONNECTION WITH THE. CASTING OF PIG METAL,"
a communication to him from abroad by George Alexander Leishman of Pittsburgh,
Pennsylvania, United States of America.
This invention relates to the casting of pig metal produced from iron ore in blast
furnaces, and to the casting floor or bed in which the metal is cast.
The usual floor or bed employed at blast furnaces is formed of silicious sand in
which the main trough leading from the furnace, and the moulds composed of the
sows" and the "pigs" are moulded. The molten metal runs from the furnace.
down the trough and into the sows, and from them into the pigs, and the pig metal
so cast being covered with sand to permit the workmen to walk over it in
"breaking up" the pigs, and being allowed to lay there until sufficiently set and
cooled for removal. It is found that in running over the sand, and cooling the
molten metal burns into and takes up part of the sand, so that a crust of about one-
half inch of combined metal and sand is formed around the pig. An allowance for
this sand and that adhering to the metal is necessarily made in selling, the usual
allowance being about twenty eight pounds to the ton. The sand so taken up, of
course increases the proportion of silica in the.metal, which is very objectionable in
certain classes of Pig Metal, such as Bessemer or foundry pig.
Pig Metal has also been cast in cast iron moulds arranged on the casting floor,
but these moulds are going out of use in large casting floors, as they chill or impart
a temper to the outer surface of the pigs, and they absorb the heat from the metal,
and require too much time for cooling. The upper surface of the metal would also
burn into the sand thrown over it, and a crust of combined metal and sand be
formed on the top of the pigs.
As a substitute for the silicious sand, the casting floor or bed has been formed of
furnace slag reduced to the necessary degree of fineness, but the slag, being a flux
formed principally of silicate of lime had no chemical action on the pig metal cast
in it, and did not wholly overcome the objections to the ordinary sand, as it adhered
to the Pig Metal and necessarily increased the proportion of silica carried into the
furnace or cupola.
The objects of this invention are:-
First. To overcome these objections found in the silicious sand, slag, or chill
casting floors and form a pig clean and free from silica adhering to it.
Second. To remove the phosphorous from the metal or reduce the proportion
contained therein.
Third: To form the grain of the metal more open, and thus adapt the ordinary
forge metal for foundry purposes, and also to improve the quality of. the metal in
other particulars.
Now the invention consists First; In casting the Pig Metal in dolomite or
equivalent basic calcareous sand and covering the Pig Metal so cast with such sand,
thus entirely enveloping or surrounding the metal with it and continuing the
process or treatment during the cooling of the metal.
Second. In a casting floor or bed for casting the pig metal formed of dolomite
sand or other sand composed of equivalent basic calcareous material, so that the
Pig Metal is cast clean and free from silicious sand, and is dephosphorized in
passing over the dolomite sand and in cooling in the moulds formed of it whereby
a stronger and more open or porous and homogeneous metal is obtained.

page_text: To enable others skilled in the art to practice the invention I will describe the
same more fully, referring for that purpose to the accompanying drawing which
represents in plan view, a casting floor of a blast furnace.
The material preferably employed for forming the improved casting floor is a
sand formed of what is termed "dolomite" being a magnesiam limestone found in
crystals about the same size as or slightly larger than common sand, and in good
condition for use without grinding or treatinent. It may also be formed by
crushing and grinding dolomite rock or inarble, but this adds to the expense of the
casting floor.
The floor may also be formed of sand composed of other equivalent basic
calcareous materials, by which term all such materials or compounds of a basic
nature having the property of withdrawing the phosphorus, or like impurities from
the metal, such as limestone, carbonate of inagnesia and like substances containing
lime or magnesia, or any of these compounded in the proper manner are included;
the best results have however been obtained in a casting bed formed of the natural
dolomite sand.
When the casting bed is formed of the dolomite sand, it is spread over the floor
in the same manner as the sand has ordinarily been employed, and the main
trough a extending from the tap hole of the blast furnace, and the moulds
composed of the sows blending from the trough and pigs care moulded in the
dolomite floor in the same manner as in the silicious sand floor. It may also be
employed with the ordinary sand floor by forming the moulds in the sand and
sifting a sufficiently thick covering of the dolomite sand over the moulds, but no
great saving will be effected in this way, as the cost of the dolomite sand is but
little above the ordinary sand, and it can be used for some time without losing its
beneticial effects as hereafter described.
In casting the Pig Metal, the molten metal flows from the tap hole down the
trough a and it is then directed into the sows b and pigs c in the usual manner;
the jigs furthest from the furnace being generally cast first and the metal in the
trough being checked by means of a paddle d pressed into the dolomite bed, just
below the next sow as soon as sufficient metal has passed to fill the lowest sow and
pigs. It is then directed into the next sow by removing the paddle at its
entrance, and the casting so continued until the entire melt is cast. As the molten
metal, in flowing through the trough, and the moulds, rolls over and over, it is
evident that almost every particle of the metal is brought into contact with the
dolomite sand, and as soon as it passes into the dolomite trough, it commences to
work or "breathe," showing that the chemical action takes place immediately, and
the phosphorus contained in the metal is absorbed or withdrawn by the basic
calcareous sand of the trough and moulds, which takes up a large portion of the
phosphorus.and silica, its action being apparently instantaneous As soon as one
Bow with its pigs is filled with the metal, the: dolomite or other basic calcareous
sand employed is spread over it with an ordinary shovel, and the pig metal is thus.
enveloped in the sand until sufficiently set and cool for removal. During the
entire time of, casting and cooling the molten metal and the pigs cast continue the
working or breathing before referred to, instead of lying dead as in the silicious
sand moulds, showing that the effect of the dolomite in the moulds and covering
extends throughout the entire mass, as the phosphorus is thus withdrawn while
the metal is in a molten state, and the metal remains in contact with, the basic
material until cooled, there is not the liability of the phosphorus returning to the
inetal, which occurs when the metal is treated at the high heats in a converter
furnace. The molten metal does not burn into the dolomite sand, and the sand
does not adhere (to any extent) to the surface of the pigs cast, so that they are
comparatively free, and clean from foreign matter, and any of the material carried
into the furnace or cupola will aid in the dephosphorizing and desiliconizing of the
metal.
The pig metal cast and treated as above.described is found to be largely reduced
in phosphorus and silica. It is clean and free from the crust of silicious sand,

page_text: formed when cast in the ordinary sand moulds, and the metal is homogeneous clear
through the pig. It has no temper or chilled surface as
the ordinary gray forge
metal is formed into the darker, more open metal, suitable for foundry purposes
and on account of the reduction of the phosphorus and silica, it is greatly
strengthened and toughened.
It is more open than that cast in common sand, so that en cast in chill moulds.
Having now particularized and ascertained the nature of the said invention in
such manner that others will be enabled to carry the improvements into effect, I
claim
First. The method herein described of casting the Pig Metal produced in blast
furnaces consisting in casting the molten metal in dolomite sand, or other sand
composed of equivalent basic calcareous material and covering the Pig Metal so
cast with such sand, substantially as and for the purposes set forth.
Second. A blast furnace casting bed or floor for casting Pig Metal formed of
dolomite sand, or other sand composed of equivalent basic calcareous material
substantially as and for the purposes set forth.
In Witness Whereof I the said John Thomson King have hereunto set my
hand and seal this seventeenth day of April in the year of Our Lord, one
thousand eight hundred and eighty three.