Improvements in the Treatment of Steel and in Apparatus therefor.
Year: 1891

page_text: Date of Application, 23rd Sept., 1891
Complete Specification Left, 22nd June, 1892-Accepted, 20th Aug., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Steel and in Apparatus therefor.
We, CHARLES WALRAND and EUGENE LEGÉNISEL, both of 95 Boulevard
Beaumarchais, Paris, in the Republic of France, do hereby declare the nature of
this invention to be as follows:-
In casting small articles in steel made in the converter difficulty is experienced
in obtaining sufficient heat and fluidity at the time of pouring. The same difficulty
is sometimes experienced in casting larger masses.
We have found that a superheating of the metal for pouring may be obtained by
so working as to ensure the presence of silicium in the metal after the removal of
the bulk of the carbon.
It is not necessary that the metal employed should be highly silicious a per-
centage of 1 to 3 gives good results.
In blowing, at the time when the frame falls we add to the metal in the
converter silicium in the form of a suitable alloy. Such flame as there was at the
time of the addition, at once disappears but the temperature rises from the com-
bustion of the silicon and the formation thereby of a non-volatile product, viz.
silica. When the carbon flame again shows, the blow is finished.
Sometimes we conduct the operation in another manner, we continue for somė
time after the fall of the flame before making the addition of alloyed silicium so,
that the bath becomes strongly oxidised. Then on the addition being made, the
combustion of the silicium takes place in the midst of the metal and the temperature
is raised as in the first case.
For charges of 200 kilos. an addition of 5% to 10% of ferro silicium con-
taining 10% of silicium is suitable.
The addition might be made in the ladle.
Silicium is not the only body which may be employed thus in the basic
operation fluidity may be given to the metal when overblown by the addition of"
an alloy rich in phosphorus, the blow being continued until the phosphorus is
consumed.'
We prefer to employ a converter having the tuyeres placed at the bottom of the
vessel and inclined to the axis so as to produce a rotation of the mass of metal
under treatment. The tuyeres may sometimes have a downward inclination all'
being set obliquely so as to produce rotation.
Dated this 23rd day of September 1891.
CARPMAEL & Co.,
Agents.
COMPLETE SPECIFICATION.
Improvements in the Treatment of Steel and in Apparatus therefor.
We, CHARLES WALRAND and EUGENE LEGÉNISEL, both of 95. Boulevard.
Beaumarchais, Paris, in the Republic of France, 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 :-
In studying attentively the progress of operations resulting in the production of
steel in a converting apparatus we have remarked that with small charges of cast
iron a considerable quantity of heat is lost by the too early combustion of the
silicium. This combustion gives birth to a solid product viz., silica and all the
Doll

page_text: heat developed is retained in the bath. Hence as in the operation of dephos-
phoration of cast irons where the phosphorus is last burnt, it is desirable that
the silicium should not be oxidised until after the departure of the carbon, so
as to lose as little heat as possible in the gases resulting from the combustion of
this latter.
We have observed that operating in a way to ensure this there was considerable
gain of heat permitting the steel to be poured at a suitable temperature which when
working on small quantities has not before been realised.
By the present invention we are able to produce cast steel in charges of little
more than 100 kilogrammes; this invention consequently principally interests the
small maker of cast steel.
In place of having recourse to cast irons reputed to be very silicious we treat
in the acid operation cast irons the silicium contents of which is unimportant
provided that the metal retains a suitable quantity of heat when it is poured into
the converting apparatus. We have proved that with various cast irons of which
the silicium contents were 15 to 3.0 per cent. the final temperature of the bath
varied very little and this dependent on the small masses upon which we operated,
for under these conditions the duration of the operation constitutes an extremely
important factor.
If at the moment when the operation is terminated (which to the converter is
indicated by the fall of the flame) there be added to the bath a certain quantity of
silicium in the form of a suitable alloy and if the blow be continued a remarkable
phenomenon results. The flame if any then remained disappears absolutely so
that one would think it was only the commencement of the blow. But little by
little it is observed that the temperature rises; it is the combustion of the silicium
which superheats the bath.
According to the proportion added (which evidently varies with the nature of
the cast iron employed and the weight of the charge treated) the blowing is
prolonged; it is continued to the instant that the carbon flame is seen to reappear.
This which seemed cold before the addition of the silicium alloy has become
extremely hot. Generally the operation is finished at this moment and the fact
is established by drawing a sample. The pouring then takes place under ordinary
conditions.
:
Sometimes, dependent on the skill of the workman, we operate in a different
way In place of making the addition of silicium or alloy of silicium on the fall
of the flame we continue the blow so as to strongly oxidise the bath. We then
add the melted alloy of silicium which reacts by the combustion of the silicium in
the bath and this raises the temperature thereof as in the first case.
The alloy of silicium may be introduced cold heated to red or best melted to
avoid all lowering of temperature.
We do not intend to limit ourselves to raising the final temperature of the bath,
by the employment of silicium only but we reserve to ourselves to utilise any
other body which in the conditions above specified is capable of combustion in the
midst of the bath so as to raise its temperature. Thus in the basic operation the
bath would be fluidified after the period of overblow by making the addition of an
alloy rich in phosphorus and continuing the blow.
As to the manufacture of steel in large masses by the Bessemer or Thomas
process the addition of silicium, of phosphorus or of other combustible body in the
conditions above specified will be attended with a certain success. It is to be
understood that the said final addition of silicium has in no way the object which
is ordinarily in view which is the deoxidation of the steel bath.
The object of this addition is to obtain a superheating of the bath such as to
allow small masses of steel to be poured at a suitable temperature which up to
the present bad not been realised. As has been already said the importance of
the addition varies with the quantities treated and the nature of the cast iron
which one uses.
The addition may also be made either a little before or a little after the fall

page_text: of the flame, the result attained being always the same, having in view the object
of the addition which we repeat is only to obtain superheating before pouring.
We have in no degree in view the increase of the silicium contents which may be
otherwise obtained either by mixture in the cupolas or by additions either hot or
cold to the pot which supplies the converting apparatus.
For charges of 200 kilogrammes for example it is well to add 5 to 10 per cent.
of 10 per cent. ferro-silicium to produce the desired effect, this however in no way
dispenses with the final deoxidising addition. The addition may be made also in
the casting pot itself in over oxidised metal.
The converting apparatus used to realise our process may be a Bessemer of the
ordinary type. But we prefer the arrangement hereinafter specially indicated.
The tuyeres are placed at the bottom of the vessel at an inclination to the axis.
so as to produce in the mass of metal under treatment a movement of rotation
favorable to the refining whilst at the same time preserving the bottom of the
vessel.
Our tuyeres may be oblique in respect to the axis of the vessel, all being
inclined in the same direction so that if we suppose the converter placed in the
position suitable for charging these tuyeres make an angle with the axis downwards
towards the sole. This inclination of the tuyeres will vary according to circum-
stances. The section of the converter so fitted may as the case may be round
square oval elliptic rectangular &c.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. The process herein described which permits of small masses of cast steel being
obtained by means of acid conversion; such process consisting in producing at the
end of the treatment in a converting apparatus before or after the fall of the
flame, a superheating by the addition into the fused mass of an alloy rich in
silicium.
2. The like process for the basic operation, consisting in producing in the same
conditions either before or after the fall of the flame, a superheating by the addition
into the fused mass of an alloy rich in phosphorus.
3. The like process substituting for alloy rich in silicium or in phosphorus, an
alloy containing a suitable combustible body other than silicium and phosphorus.
Dated this 16th day of June 1892.
CARPMAEL & Co.,
Agents for the Applicants.