Improvements in Effecting the Recarburization of Steel or Ingot Iron.
Year: 1889

page_text: Date of Application, 22nd May, 1889
Complete Specification Left, 20th Feb., 1890-Accepted, 22nd Mar., 1890
PROVISIONAL SPECIFICATION.
Improvements in Effecting the Recarburization of Steel or
Ingot Iron.
I, THOMAS TWYNAM, of 7 Marlborough Crescent, Bedford Park, in the County of
Middlesex, Metallurgical Chemist, do hereby declare the nature of this invention to
be as follows:-
My invention relates to an improvement in the process of recarburizing the very
low carbon steel or ingot iron produced in the open hearth or Bessemer process, so as
to to produce therefrom steel of any wished for percentage of carbon.
Hitherto it has been extremely difficult to produce high carbon steel except by
means of the crucible process of steel making which besides being an expensive
method, only produces small quantities at a time. Although my invention is more
particularly suited for use in connection with the open hearth process of manufacture
it can also be applied to the Bessemer process. When it is wished to produce by
means of the open hearth process steel of a determined percentage of carbon,
proceed as follows-I first calculate what amount of carbon, preferably in the form of
pure wood charcoal will be required to give the wished for percentage of carbon to
the weight of steel in the furnace, and allow a certain excess above the calculated
amount, after allowing however for the residual carbon left in the bath of metal at
the time of tapping.
The weight of charcoal thus found is carefully placed in the manner hereinafter
described in the "chute " or trough through which the fluid metal passes on its way
to the ladle. The charge of metal in the furnace having been sufficiently purified, is
tapped and the molten metal allowed to flow over the charcoal arranged in the chute
or trough. The metal rapidly eats up the charcoal, producing in the ladle steel of the
wished for percentage of carbon, which is subsequently tapped out of the ladle into
the ingot moulds.
The following is the method I find most advantageous for arranging the charcoal in
the trough or chute. The latter, which may be of the usual size, but which when
convenient I always prefer to be somewhat longer and wider than is usually used, is
lined with fireclay bricks, of which some at the sides project about two inches or less
beyond the rest. Between these projecting bricks sticks of charcoal are loosely placed,
three or four pieces being placed one above the other and separated by cross pieces.
Care should be taken that the flow of metal be not unduly checked. The sticks of
charcoal are prevented from being swept into the ladle by the current of molten steel,
by the projecting bricks. I generally find it more convenient to place moveable
covers over the chute before the metal is tapped as there is a very considerable
evolution of sparks. The metal will first eat up or dissolve the lowest row of sticks
or lumps of charcoal, allowing the upper layers to fall somewhat; and this will
continue until all the charcoal is consumed.
It will be seen that by this arrangement the charcoal is only gradually presented to
the metal, thus allowing for an equitable distribution of carbon in the metal.
It will frequently be found more convenient to have the chute curved at a con-
siderable angle or to have it arranged in two sections so that the second section is at
right angles to the first and can be readily detached from it. By this arrangement it
is possible to get a longer length of chute and consequently more charcoal in it, it
is also more convenient for working the furnace that that part of the chute which is
attached to the launder of the open hearth furnace should be readily removed
independently of the other part.
I am aware that it has been proposed to filter molten soft steel through charcoal

page_text: held in a special receptacle for the purpose of recarburizing it, but this necessitates
considerably more plant and a deeper pit than is usually employed and forms no part
of my invention.
Dated this 001 L
M
1000
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Effecting the Recarburization of Steel or
Ingot Iron.
I, THOMAS TWYNAM of 7 Marlborough Crescent, Bedford Park, in the County of
Middlesex, Metallurgical Chemist, do hereby declare the nature of this invention and
in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
My invention relates to an improvement in the process of recarburizing the very
low carbon steel or ingot iron produced in the open hearth or Bessemer process so as
to produce therefrom steel of any wished for percentage of carbon. It is, more
particularly applicable to steel made by the basic process of manufacture.
Hitherto it has been extremely difficult to produce high carbon steel except by
means of the crucible process of steel making which besides being an expensive
method only produces small quantities at a time. Although my invention is more
particularly suited for use in connection with the open hearth process of manufacture,
it can also be applied to the Bessemer process.
When it is wished to produce steel of a determined percentage of carbon I proceed
as follows:-
I first calculate what amount of carbon in the form of pure wood charcoal, gas or
retort carbon or other convenient form of carbon will be required to give the wished
for percentage of carbon to the weight of steel in the furnace and allow a certain
excess which may be taken at about 25% above the calculated amount, after
allowing however for the residual carbon left in the bath of metal at the time of
tapping.
The weight of carbon thus ascertained is according to my invention to be incor-
porated or taken up by the molten metal in its passage from the furnace to the ladle.
For this purpose I proposed in my provisional specification as a convenient arrange-
ment that the carbon should be in the form of sticks, the ends of which were to rest
against bricks projecting for say 2 inches from the sides of the chute at suitable
intervals, and I find by my subsequent experiments that by this arrangement a certain
percentage of carbon can be advantageously introduced into the metal but where a
considerable quantity of carbon is to be incorporated the number of such sticks have
a tendency to check the flow of the metal, and to obviate this objection I now propose
when making high carbon metal to introduce the carbon or at least a portion of it in
small pieces in that part of the chute nearest the furnace, and as the metal impinges
against the projecting bricks or against the projecting bricks and carbon sticks any
of the added carbon which floats on the surface is drawn down and becomes incor-
porated with the metal as it eddies or curves over at these points.
When the charge of metal in the furnace has been sufficiently purified it is tapped
out, and the molten metal allowed to flow down the chute or trough into the ladle.
The metal rapidly absorbs the carbon as it is presented to it producing in the ladle
steel of the wished for percentage of carbon, which is subsequently tapped out of the
ladle into the ingot moulds. The chute employed may be of the usual size but when
convenient I always prefer it to be somewhat longer and wider than is generally
employed. It will frequently be found more convenient to have the chute curved at
a considerable angle or to have it arranged in two sections so that the second section
is at right angles to the first and can be readily detached from it. I generally find it
convenient to place movable covers over that part of the chute nearest the ladle as
there is a very considerable evolution of sparks.

page_text: I am aware that it has been proposed to filter molten soft steel through charcoal
held in a special receptacle for the purpose of recarburizing it, but this necessitates
considerably more plant than is usually employed and forms no part of my invention.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
:-
The improvements in effecting the recarburization of steel or ingot iron which
consists in adding a suitable weight of carbon to the molten metal while it is flowing
down a chute or trough before reaching the ladle, substantially as described.
DL: 10th deve
Bahena 1800
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London, Applicant's Agent.