AN IMPROVED PROCESS OF TREATING WITHOUT MELTING CAST IRON, IRON, BESSEMER METAL, MARTIN METAL, AND OTHER METALS PROCEEDING FROM THE FINING OF CAST IRON IN ORDER TO TRANSFORM THE SAME IN FINE STEEL
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by Léon Krafft and Hippolyte Julien-
Sauve, fils, at the Office of the Commissioners of Patents on the 23rd
December 1870.
LÉON KRAFFT and HIPPOLYTE JULIEN-Sauve, fils, both of Boulevard Saint
Denis, No. 1, at Paris, Chemists. "AN IMPROVED PROCESS OF TREATING WITHOUT
MELTING CAST IRON, IRON, BESSEMER METAL, MARTIN METAL, AND OTHER METALS
PROCEEDING FROM THE FINING OF CAST IRON IN ORDER TO TRANSFORM THE SAME
IN FINE STEEL."
The known processes for transforming iron into steel (refining by the oxygen of
the air or the Bessemer method, refining by reaction or Reaumur's method, im-
proved by Siemens and Pierre Emile Martin and others) ingenious as they are do
not and cannot give but imperfect intermediate compositions between the castings
of true iron and steel.
Although of undoubted utility and of a low price these products are not applicable
to any of the manufactures requiring fine steel.
To overcome these defects and to give to the metals the requisite qualities we
subject them for some hours to a red heat in a retort filled with carbonaceous
matter over which is slowly passed a current of azote, of carbonic oxide, and of
various carbonated hydrogens. We introduce wood, vegetable charcoal, peat, coke,
or any like kind of vegetable materials, very dry and heated to a temperature of
about 50° degrees, into a hydrocarbon oil of any kind (such as the heavy oil of
schist) which is also heated to the same temperature. This latter is absorbed in the
proporation of from twelve to fifteen per cent., and we form with bars of Bessemer
metal, Martin metal, or any other product arising from the refining of cast metal as
above mentioned alternate layers, the whole being enclosed in a vessel (similar to a
gas retort and of desired form) and heat gradually to a red heat. By these means
the excess of oxygen that is contained by the vegetable materials in presence of the
vapourised hydrocarbons is transformed into carbonic oxide and their ozote into
ammonia in such wise that the metals under treatment are immersed in a gaseous
medium, which is allowed to be the best for the purpose of converting them into
fine steel. Now as it may occur that before this absolute conversion the productive
source of the gas may be exhausted by distillation we provide against this incon-
venience by passing through the apparatus a current of carbonic acid or carbonic
oxide mixed or not with azote. When we obtain this gaseous mixture from the
products of the combustion of the furnace which serves to heat the apparatus
Price 2d.]

page_text: we separate from it its free oxygen and change it to carbonic oxide by causing
it to pass over carbonaceous matter heated to red heat before it is passed to the
metals.
In the Siemens, Ponsard, Muller, and other retorts, the principle of which consists
in the gasification of combustibles, we give a mixture of the gases, which we employ
equally to the heating of the apparatus as to the transformation of the metal to
steel. The gas which escapes from these furnaces also serves for this double purpose.
When, on the contrary, we obtain this gaseous medium by direct calcination of
limestone or the mixture of this with carbons, the gaseous products (carbonic acid
and carbonic oxide) are passed directly into the apparatus containing the layers of
charcoal and metal. We obtain at the same time from the lime which we may
convert into pyrolignite of lime the little pyroligneous acid which separates equally
from the wood as from the hydrocarburetted peat during the heating to red
heat, and which we take care to collect as is ordinarily done in the distillation of
wood.
It will be understood that the mixed gases produced and composed in and that
have passed through the apparatus may on their passage therefrom be collected in a
gasometer to be again used for the same purpose or passed under the furnace of the
apparatus, where they will be utilised as combustibles.
If the products propared according to our process are melted, cast steel of the
finest quality will be obtained, and by these means we may obtain without melting
steel of the first quality for the manufacture of files and other articles from Bessemer
metal, Martin metal, and generally from all metals which are obtained from cast-
ings, either by refining with the oxygen of the air or by refining by reaction.
In addition to the steel we obtain simultaneously and at will from the lime, the
ammonia, and the pyroligneous acid tarry hydrocarbons, which we use over again,
and wood or peat charcoal of denser quality than that used originally, not only fit for
domestic purposes but for use in metallurgy.
If cast iron particularly is acted upon, and if this cast metal heated to red heat is
exposed in a retort to a current of carbonic acid alone or mixed with air it will be
transformed into steel, and the gas will become carbonic oxide, which in passing
into another retort charged with Bessemer metal at red heat will effect the con-
version of this metal into fine steel, and will itself be reconverted into carbonic acid.
Thus the carbonic acid (CO2) raised to the casting its excess of carbon (C) is
transformed into carbonic oxide (200), this passing over the iron of the Bessemer
metal and the like will give up the carbon (C) and will return to the state of
carbonic acid (CO). From this a given volume of carbonic acid gas being given
enclosed in a gasometer they may by passing this gas in the retorts heated to red
heat and charged, the first with cast iron, the second with Bessemer metal, the third
with cast iron, and the fourth with Bessemer metal, and thus in succession (pro-
vided that the series commencing with cast iron terminates with one or two retorts
charged with Bessemer metal) to transform the whole of the metal into steel, and
on collecting the gas in a second gasometer the same operation may be recommenced,
and so on indefinitely.
If the passage of the gas takes place in a converter charged with melted cast iron
the transformation of the casting is more regularly and easily done, and with less
loss of iron.