Wrought
Year: 1888

page_text: I ALBERT EDGAR ALEXANDER of 19 Southampton Buildings in the County of
Middlesex Fellow of the Institute of Patent Agents do hereby declare the nature of
this invention (communicated to me from abroad by Lucius D. Chapin of Hyde Park in
the County of Cook and State of Illinois in the United States of America) to be as
follows:-
"
An improved method of manufacturing Wrought Iron heretofore devised by the
communicator and now commonly known in the art as "The Chapin Pneumatic Process"
may be stated generally to consist in subjecting a charge of molten cast Iron in a
pneumatic converter having a fire-brick, ganister, or like silicious lining to the action
of an air-blast as in the usual process of making Bessemer metal the blow continuing
until the objectionable impurities which the air-blast is adapted to remove shall have
been substantially eliminated or so far eliminated that the presence of the residue will
not in subsequent working prevent the production of good Iron. The metal is then
transferred to a separate balling chamber having a basic lining preferably of Iron Oxide
and there exposed to a reverberatory flame at the same time that the metal is
mechanically agitated for the purpose of bringing it to " nature and thus in condi-
tion to form a ball or loop. As it leaves the converter the molten charge of Iron is
so far advanced to a wrought condition that only a few minutes exposure in the
balling chamber is necessary to perfect the reduction and allow for the formation of
the loop. It is plain that this method is very expeditious in comparison with the
older methods of making wrought Iron, and that besides it has the merit of working
upon much larger masses of metal insuring great homogeneity for a larger product.
The practice of the process thus outlined is attended with excellent results if the
cast-iron under treatment be comparatively free from Phosphorus. This requirement
necessarily excludes a vast range of ores and pig metal from utilization which under
the old methods of making wrought iron were entirely available for the purpose. Any

page_text: material per-centage of Phosphorus present in the metal to such extent for instance,
as would lead to the rejection of the Iron in the ordinary Bessemer method employing
an acid lining converter is prejudicial also against its use for the production of best
wrought Iron by the process stated since it is well understood that the action of the
air-blast under usual conditions upon the charge of metal in a pneumatic converter
having an acid lining does not effect the removal of the Phosphorus at least to any
considerable degree.
The present invention is therefore directed primarily to such modifications in the
above mentioned process of making wrought Iron, which, whilst retaining the general
plan of a preliminary or first stage of treatment of the cast metal in a pneumatic
converter having an acid lining and a second stage of treatment of the charge in a
balling chamber under a reverberatory flame and puddling action is yet varied so far
as to permit the use of highly silicious and Phosphatic pig metal and to ensure the
substantial removal of these impurities. The product obtained by the modified
method although reduced ordinarily by squeezing and rolling to the various shapes
and merchant bars usual to wrought Iron is also available for use in the manufacture
of Steel more especially by the open-hearth process. The wrought metal being low
in its content of Carbon and practically free from Phosphorus is peculiarly fitted to
serve as the addition in tempering the bath of cast Iron according to the Siemens-
Martins method.
To accomplish the objects in view the first part of this invention consists in
subjecting molten cast Iron in a pneumatic converter having preferably a fire-brick,
ganister or like acid lining to the action of an air-blast until the Silicon is substantially
removed sufficient Carbon being retained to preserve the desired fluidity of the metal
then transferring the molten charge to a separate furnace or balling chamber having
a comparatively inert and refractory lining and suitable basic reagents above the same
to nourish the Iron and unite with the Phosphatic and other impurities and subjecting
said charge in such chamber to a reverberatory flame and to puddling action until the
metal is reduced to wrought condition to form a ball or loop. This first part of the
invention also consists in certain improvements in detail of the process outlined, the
nature of which will fully appear from the following description and be thereafter
distinctly pointed out in the claims at the conclusion of this specification.
In the practice of the process above concisely outlined the molten Iron is taken
from the cupola, blast furnace, or other melting appliance, into a converting vessel of
the usual or of any other suitable form and dimensions adapted to the practice of the
pneumatic or Bessemer method of reducing cast Iron. The converter may be of the
fixed type, or may turn upon trunnions as well understood and the manner of charging
the same and of operating and controlling the air-blast is in accordance with that
nsually practiced. The converter is lined with fire-brick ganister or like acid lining
because such lining is comparatively cheap and durable although any other usual
lining may serve. The blast of air being injected through the molten metal soon
begins to oxidize the Silicon associated therewith and shortly after but with less
intensity at first to oxidize the contained Carbon. The use of the air-blast is thus
continued until the Silicon which is most rapidly oxidized has been in large part con-
verted into Silicic acid and as a Silicate has passed into the cinder. At this stage the
elimination of the Carbon is well advanced although enough still remains in the
charge to preserve its fluidity even when the temperature is somewhat abated. The
point at which the greater part of the Silicon has become oxidized and passed into
the Slag and the point therefore when the desiliconizing of the metal ceases to be
powerfully and effectively antagonistic to its dephosphorization is indicated either
by the character of the Slag produced or by the character of the flame. In the former
case the element of the Silicate of the Protoxide of Iron falls to at least or below
25 per cent. of the Slag; in the latter case the flame abates somewhat of its volume
keeping at the same time progressively towards a darker hue and becoming purplish
which change the practiced eye of the operator detects with great certainty. Either
of these but particularly the latter because easily available in the circumstances would
mark the time when the blow should be brought to a close. It is obvious that the

page_text: percentage limits stated must vary because of the difference in composition in the
various kinds of pig metal which may be treated. The desiliconizing effect of
the air-blast having proceeded to the extent stated still retaining sufficient Carbon to
insure the desired fluidity of the metal the blow is then completed and the blast shut
off from the vessel. The conditions of the operation are now changed from those
requisite for desiliconizing metal to those appropriate for its dephosphorization to
which end the charge is transferred from the converting vessel by means of
ladle or
other convenient device into a reverberatory chamber in readiness to receive the same
as hereinafter described. In transferring the metal care is to be taken to exclude as
much as possible of the Silicic cinder forined in the converter and for the same reason.
it is preferred to withdraw the metal from the transfer ladle through the bottom
of the ladle after the manner of casting ingots in the Bessemer process although a
trunnion ladle may be used if desired. The metal may run into a funnel or spout
which is a part of the dephosphorizing and balling chamber and is delivered thereby
into the interior of the chamber. The balling chamber may be of any usual or con-
venient construction having either a fixed or moveable or revolving hearth or what is
preferable may be a rotary haller of the Dank's pattern. It is merely necessary that.
the chamber shall be such as to admit a reverberatory flame over the charge and to
permit the latter to be puddled by hand or mechanically for the purpose of bringing
it to "nature." In working the process upon a commercial scale a series of balling.
chambers may be economically employed in conjunction with the single converting
vessel. Each of the reverberatory hearths or chambers is to be prepared for the
reception of the partially converted charge in substantially the following manner,
namely: Upon a layer of fire-brick, fire-clay or other support is arranged a sub-lining
of Chrome Iron Ore or other refractory ore of Iron although, the Chrome Ore is
preferred because of its resistance to the corrosive influence of the remnant of Silicon
present in the charge. The Chrome Iron Ore employed should preferably contain at
least 37 to 38% of Chrome Oxide and not more than 6% of Silicon in its com-
position. In the case of the rotary baller the use of which is preferable an arch of
the Crome Ore is turned over the entire inner surface of the vessel and in any event
should be made to cover all parts of the interior of the chamber exposed to the metal
bath. The lumps of ore constituting the sub-lining should be grouted at their joints
with pulverized ore of like composition reduced to a thick mortar and rammed into
the interstices. If necessary a small portion of suitable fire-clay may be added to
the slip but the use of this should be avoided if possible. The sub-lining thus
arranged subserves a double purpose furnishing a wall refractory to the presence of
heat and resisting also the corrosive action of such remnant of Silicon as may have
passed into the baller. More especially is this true of the Chrome Iron Oxide which
on this account is preferred in the construction of the sub-lining. Above the sub-
lining is spread a superficial or surface lining consisting of the oxides of Iron either
in the form of suitable ore or mil cinder to which may be added pulverized
Dolomite, in more or less amount according to the percentage of the Phosphatic
impurity existing in the charge. The presence of the Dolomite increases the basic
character of the surface lining and supplies more bountifully a material with which
the Phosphoric acid may unite and pass into the slag. Good effects may be pro-
duced by employing 50 parts of Haematite Ore to 25 parts of Mill Cinder and 25
parts of Dolomite in making the surface lining although it is evident that these
proportions may be varied at will; the Dolomite and Mill Cinder or either may be
omitted entirely, if the metal is very low in Phosphorus. The refractory chamber
being suitably heated the requisite amount of superficial lining or fix is spread upon
the sub-lining and in case of the rotary baller when the fix shows signs of reducing
under the heat the baller is set slowly in motion and so continues until the superficial
lining or fix is evenly spread over the entire surface exposed to the bath. Thus
prepared the chamber is in readiness to receive the charge from the transfer ladle
which being delivered is exposed to the powerful reducing action of the reverberatory
flame and at the same time subjected to puddling action necessary to expose the metal
and to collect it finally into a ball or loop the time necessary for the completion of

page_text: the second stage of treatment in the reverberatory hearth is brief but will vary according
to the condition of the metal in respect both to the amount of Carbon still remaining
therein and that of the Phosphorus. Because the Carbon is retained to a consider-
able extent the fluidity of the charge is thereby enhanced so that the metal flows and
is better exposed to the oxidizing influence of the flame. For the same reason the
Phosphoric acid as produced reacts more rapidly with the surface lining and escapes
into the Slag before the reduction of the Carbon to the desired minimum is finally
accomplished. The Silicon having been practically eliminated in the first stage of the
process under its appropriate conditions presents no obstacle to the speedy
disappearance of the Phosphorus under the favourable conditions presented for the
accomplishment of such object in the second stage of the process. The remnant of
Silicon retained in the charge as it comes into the balling chamber quickly combines
with the surface-lining and passes into the Slag. If such lining wears away the
Chrome Iron Oxide sub-lining beneath will not be attached by the free Silicic acid so
that the substantial wall of the chamber remains practically unaffected. It is thus
manifest that the necessity for relining the balling chamber which was before requisite
in treating highly silicious and Phosphatic pig metal after a few heats is no longer
required. The superficial or fix lining may be easily and cheaply restored and under
the favourable condition provided in the balling chamber furnishes appropriate
means for the complete elimination of the Phosphorus before the charge has been
finally reduced to the condition of a puddle ball or loop. The loop produced is
removed from the furnace in any convenient way and passes to the squeezer or
hammer for the expulsion of the cinder after which the muck bar or billet may be
rolled into merchant shape or clipped up for the manufacture of open hearth steel as
desired.
The second part of this invention has for its object to insure the delivery of the
metal into the balling chamber with a percentage of carbon best calculated to insure
the most perfect treatment of the metal in such chamber to enable the finished
product to possess any desired percentage of Carbon and to secure the practical
elimination of the phosphorus therefrom.
In the practice of the second part of the said invention the molten Iron is taken or
run from the cupola or blast furnace into a suitable converting chamber in the same
manner as in the process constituting the first part of this invention. The molten
metal is then subjected to the action of the air blast, the Silicon being first oxidized
and gradually passing from the metal into Silicic acid and as a Slag into the cinder
and the Carbon being also at the same time oxidized until at the end of the blast
which will be of about or slightly more than, the ordinary duration, the metal will
have been practically freed from all impurities which the pneumatic treatment in an
acid-lined converter is adapted to remove. The point when the desiliconization and
decarburization of the metal is substantially completed can be readily determined by
the spectroscope or by the practised eye of the operator from the character of the flame.
When the metal within the converter has been thus freed from the impurities which
the converter treatment is adapted to eliminate the molten mass will next receive an
addition of Ferro-Manganese, Spiegeleisen or other suitable carbonaceous material for
the purpose of imparting to the mass any desired percentage of carbon before the
mass is finally subjected to treatment in the puddling or balling chamber.
addition of Ferro-Manganese or Spiegeleisen, may be made either by pouring the
same into the converter at the end of the blow or by pouring the same, or delivering
it in pulverised and heated condition into the ladle by which the metal is transferred
from the converter to the puddling or balling chamber for final treatment
the ferro-manganese or Spiegeleisen has been thus added the molten metal will be
transferred to the puddling or balling chamber which may be of any usual or con-
venient construction having either a fixed or moveable or revolving hearth or which is
preferable, may be a rotary baller.
This
After
It is preferred' to conduct the final treatment of the metal in a puddling or
balling chamber having a lining such as that described in connection with the process
treatment defined in the first part of this specification and with the addition of the

page_text: basic reagents there mentioned.
Within such chamber the charge will be received
from the transfer ladle and will be exposed to the powerful reducing action of the
reverberatory flame and will at the same time be subjected to puddling action necessary
to expose the metal and to collect it finally into a ball or loop.
The time necessary
for the completion of this puddling or balling treatment is brief, but will vary
according to the condition of the metal both in respect to the amount of Carbon
therein contained and the percentage of Carbon desired in the finished product and
the amount of Phosphoric impurities. The Silicon having been eliminated in the
converter stage of the process and sufficient Carbon having been added to insure the
proper fluidity of the charge and give the required percentage of Carbon to
the finished product, it is obvious that the metal is in best condition for insuring the
reaction between the material of the surface-lining of the chamber and the additions
of basic material and the Phosphoric impurities present in the metal. By adding
the Ferro-Manganese or Spiegeleisen to the charge of metal before its final
treatment in the puddling or balling chamber a much more homogeneous
quality of metal is ensured for the reason that the charge being in much more fluid
condition the Carbon will consequently be more thoroughly distributed throughout
the mass, and all portions of the charge will be more uniformly and thoroughly
exposed to the action of the basic reagents and of the reverberatory flame.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The process of making wrought iron which consists in subjecting molten cast
iron in a pneumatic converter having preferably a fire-brick, ganister, or like acid
lining to the action of an air-blast until the Silicon is substantially removed sufficient
carbon being retained to preserve the desired fluidity of the metal then transferring
the molten charge to a separate furnace or balling chamber having a comparatively
inert and refractory lining and suitable basic reagents above the same to nourish the
iron and unite with the Phosphatic and other impurities and subjecting said charge
in such chamber to a reverberatory flame and to puddling action until the metal is
reduced to wrought condition to form a ball or loop substantially as described.
2. The process of making wrought iron which consists in subjecting molten cast
Iron in a pneumatic converter having preferably a fire-brick, ganister, or like acid
lining to the action of an air-blast until the Silicon is substantially removed sufficient
carbon being retained to insure the desired fluidity of the metal then transferring the
charge to a separate furnace or balling chamber having a Chrome Iron Oxide or like
inert and refractory sub-lining and a surface lining or fix above the same of suit-
able basic character to nourish the Iron and react with the Phosphatic or other
impurities and subjecting the charge in such chamber to a reverberatory flame and to
puddling action until the metal is reduced to wrought condition to form a ball or loop
substantially as described.
3. The process of making wrought Iron which consists in subjecting molten cast
Iron in a pneumatic converter having a fire-brick ganister or like acid lining to the
action of an air-blast until the Silicon is substantially removed, sufficient carbon being
retained to insure the desired fluidity of the metal then transferring the charge,
practically freed from the converter cinder, to a separate furnace or balling chamber
having a chrome Iron Oxide sub-lining and a surface lining or fix above the same
composed of Mill Cinder or other fusible Iron Oxide and Dolomite combined in
suitable proportions to nourish the iron and react with the Phosphatic or other
impurities and subjecting the charge in such chamber to a reverberatory flame and to
puddling action until the metal is reduced to wrought condition to form a ball or loop
substantially as described.
4. The process of manufacturing iron which consists in subjecting molten cast
iron in a pneumatic converter having preferably a fire-brick, ganister, or like acid
lining to the action of an air-blast until the Silicon or other impurities and as
well also the Carbon have been practically eliminated then adding to the molten

page_text: mass, ferro-manganese Spiegeleisen or other suitable carbonaceous material in
sufficient quantity to impart to the molten metal a percentage of Carbon sufficiently
in excess of the percentage desired in the finished product to compensate for the
loss of Carbon during the subsequent treatment of the metal and finally subjecting
the molten metal to the action of a reverberatory flame in a basic lined puddling
or balling chamber with suitable additions of basic material until the Phosphorus
has been eliminated and the carbon has been reduced to the desired percentage
substantially as described.
Dated the Eighteenth day of Sentember 1888