Improvements in the Manufacture or Purification of Steel or Homogeneous Metal.
Year: 1891

page_text: Date of Application, 13th Feb., 1891
Complete Specification Left, 12th Sept., 1891-Accepted, 17th Oct., 1891
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture or Purification of Steel or
Homogeneous Metal.
I, JOHN HENRY DARBY, of Brymbo near Wrexham, in the County of Denbigh,
Iron and Steel Manufacturer, do hereby declare the nature of this invention to be
as follows:-
In Specifications Nos. 41888 2058689 and 4030" I have described a process of
re-carburising iron or steel.
While I have found the process described in these Patents work well in practice
and for the purposes for which it is suited still for the manufacture of steel as free
as possible from sulphur, phosphorus, arsenic and manganese, a variation in the
procedure is found more desirable.
It is found difficult to obtain commercially a suitable pig iron from which to
manufacture steel containing, when the manufacture is completed, not more than
01 per cent. of sulphur, 01 per cent. of phosphorus and under 1 per cent. of
manganese. White hematite pig iron which would otherwise be suited for this
purpose is difficult to make sufficiently low in manganese, silicon and sulphur, and
it is therefore expensive, but basic pig iron low in silicon and sulphur and
containing phosphorus and manganese is made commercially and cheaply. This
phosphoric pig iron is not suitable for the manufacture of steel of about the
composition given by methods at present employed.
This invention is designed to so modify the method of manufacture that a cheap
basic pig iron may be utilised for the manufacture of the very highest class of
finished steel.
I effect this object by re-carburising the steel and again exposing it to oxidation
in a basic convertor basic lined open hearth furnace or its equivalent, whereby the
impurities, only partially eliminated in the first treatment, are further reduced, or,
what is equivalent, I continue and prolong the basic process for the manufacture of
steel by continually or intermittently or in a single dose adding carbon to the iron
as the other metalloids become oxidised. This can be done by admitting carbon to
the convertor or pouring out the iron, adding carbon to it in the ladle and returning
it again to another convertor or basic lined furnace for further treatment, or
pouring the steel from the first convertor or hearth to a second containing the
requisite carbon.
The method of carrying out my invention, which from my experiments appears
the most feasible, at present, is as follows:-
The basic pig iron spoken of is treated, either in a convertor, an open hearth or
other furnace, lined with basic material and converted into soft steel by the usual
methods. Its probable composition, when ready to tap, would be, sulphur 02 to
04 per cent., phosphorus 03 to 05 per cent., silicon nil, manganese 15 to 25 per cent.,
carbon 07 to 12 per cent. This material is re-carburised, by the aid of the process
described in my former Patents referred to, to the extent of 1 to 1.50 per cent., and
the re-carburised molten metal or ingots, produced therefrom, are either run or
charged into a second basic lined open hearth furnace. If the furnace has been
previously working phosphoric charges, it will take two or three heats before the
phosphorus contained in the lining and the slag adhering thereto is washed out of
the furnace, and, until that takes place, the quality will not be so good as after this
is accomplished. To this charge a certain percentage of grey hematite pig may be
added, say 10 to 20 per cent. of the whole charge. When thoroughly melted, it
should be worked in the usual way with lime stone, lime and iron ore additions, if

page_text: necessary, until the carbon, phosphorus, sulphur and manganese are eliminated to
the required extent.
The charge is then tapped and, if necessary, re-carburised a second time to the
desired percentage for hard steels, or teemed without any further addition for other
special purposes. It will be found that, the second time of melting and working,
the charge works freely from the first and does not froth and delay the process as is
usually the case with hematite pig iron.
Dated this 12th day of February 1891.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Manufacture or Purification of Steel or
Homogeneous Metal.
I, JOHN HENRY DARBY, of Brymbo, near Wrexham, in the County of Denbigh,
Iron and Steel Manufacturer, 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 Specifications Nos. 41888, 205868 and 403000 I have described a process of
re-carburising iron or steel.
While I have found the process described in these Patents to work well in
practice and for the purposes for which it is suited, still for the manufacture of steel
as free as possible from sulphur, phosphorus, arsenic and manganese, a variation in
the procedure is found more desirable.
It is found difficult to obtain commercially a suitable pig iron from which to
manufacture steel containing, when the manufacture is completed, not more than
⚫01 per cent. of sulphur, '01 per cent. of phosphorus and under 1 per cent. of
manganese. White hematite pig iron which would otherwise be suited for this
purpose is difficult to make sufficiently low in manganese, silicon and sulphur, and
it is therefore expensive, but basic pig iron low in silicon and sulphur and
containing phosphorus and manganese is made commercially and cheaply. This
phosphoric pig iron is not suitable for the manufacture of steel of about the
composition given by methods at present employed.
This invention is designed to so modify the method of manufacture that a cheap
basic pig iron may be utilised for the manufacture of the very highest class of
finished steel.
I effect this object by re-carburising the steel and again exposing it to oxidation
in a basic converter, basic lined open hearth furnace or its equivalent, whereby the
impurities, only partially eliminated in the first treatment, are further reduced, or,
what is equivalent, I continue and prolong the basic process for the manufacture of
steel by continually or intermittently or in a single dose adding carbon to the iron
as the other metalloids become oxidised. This can be done by admitting carbon to
the converter or basic lined furnace, or pouring out the iron, adding carbon to it by
the aid of the process described in my former Patents referred to and returning it
again to another converter or basic lined furnace for further treatment, or pouring
the steel from the first converter or hearth to a second containing the requisite
carbon.
The method of carrying out my invention, which from my experiments appears
the most feasible, at present, is as follows:-
The basic pig iron spoken of is treated, either in a converter, an open hearth or
other furnace, lined with basic material, and converted into soft steel by the usual
methods. To illustrate the process I will describe it as applied to the basic open
hearth furnace. The composition of the metal, when ready to tap, would be,
sulphur 02 to 0 per cent., phosphorus 03 to 05 per cent., silicon nil, manganese 15

page_text: to 25 per cent., carbon 07 to 12 per cent. This material is re-carburised, by the
aid of the process described in my former Patents referred to, to the extent of 1 to
1.50 per cent., and the re-carburised molten metal or ingots. produced therefrom,
are either run or charged into a second basic lined open hearth furnace with a
certain percentage of grey hematite pig iron, say 10 to 20 per cent. of the whole
charge. When thoroughly melted, it should be worked in the usual way with lime
stone, lime and iron ore additions, if necessary, until the carbon, phosphorus,
sulphur and manganese are eliminated to the required extent. The charge is
then tapped and, if necessary, re-carburised a second time to the desired percentage
for hard steels, or teemed without any further addition for other special purposes.
If the furnace has been previously working phosphoric charges, it will take two or
three heats before the phosphorus contained in the lining and the slag adhering
thereto is washed out of the furnace, and, until that takes place, the quality will not
be so good as after this is accomplished. It will be found, that, the second time of
melting and working, the charge works freely from the first and does not froth and
delay the process as is usually the case with hematite pig iron.
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 the manufacture or purification of steel or homogeneous
metal which consist in increasing the period of oxidation in the basic lined Bessemer
converter, basic open hearth or other like plant by the addition of carbon and
subsequent re-oxidation, substantially as and for the purposes herein described.
Dated this 11th day of September 1891.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicant.