Improvements in the Manufacture of Iron and Steel.
Year: 1892

page_text: Date of Application, 6th Apr., 1892
Complete Specification Left, 6th Jan., 1893-Accepted, 25th Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Iron and Steel.
I, THOMAS TWYNAM of 10 Blandford Road Bedford Park Chiswick, W.
Metallurgical Chemist do hereby declare the nature of this invention to be as
follows :-
This invention relates to improvements in the manufacture of ingot iron and steel
as manufactured by the basic Bessemer process. Many varieties of pig iron are
too high in silicon and too low in phosphorus to be economically treated by the
basic Bessemer process, and it is to such varieties of pig iron that my invention is
more particularly applicable. It is often more economical for the blast furnace
manager to make a pig iron higher in silicon than is generally used in basic
Bessemer working, than to make a suitable basic pig iron, and the danger of high
sulphur is less with the former than with the latter variety.
To the molten pig iron, fairly high in silicon and low in phosphorus, that it may
be desired to treat by the basic Bessemer process, I add a suitable quantity of basic
slag or ferruginous phosphoric cinder, both of which I always prefer should be in
the molten condition. The silicon in the pig iron rapidly reacts upon the phosphoric
acid contained in the slag, reducing the latter to phosphorus and oxidizing itself to
silica at the expense of the oxygen of the phosphoric acid; the reduced phosphorus
enters the metal increasing the percentage of phosphorus therein to a corresponding
extent.
I apply this reaction in practice, either by running some of the slag from a
previous charge into the ladle containing the pig iron, from whence both may be
run together into the converter, thus effecting a through mixture of the two, or by
retaining a part of the basic slag in the vessel after finishing and pouring a heat,
and running in upon the slag so left the high silicon pig iron.
The vessel should be rocked to facilitate the reaction of the metal on the slag.
Sometimes even I blow for a short time to well mix the two together. The
resulting slag, containing the oxidized silicon, may be poured off.
The reaction is the same when using ferruginous phosphoric cinder, this also is
preferably used molten, either by melting it in the vessel itself, or by a preliminary
melting down in a small cupola, or other convenient furnace before adding it to the
pig iron.
When the pig iron is not used direct from the blast furnace, the metal and slag
may be melted down together in the cupola.
The above described method of working may advantageously be employed when
oxides of iron, such as tap cinder, reheating furnace cinder etc., are added at the
commencement of the blow for the purpose of shortening the afterblow and obtaining
a basic slag high in phosphoric acid.
Dated this 4th day of April 1899
'
THOMAS TWYNAM.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Iron and Steel.
I, THOMAS TWYNAM of 10 Blandford Road Bedford Park, Chiswick, W.
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 :-
This invention relates to improvements in the manufacture of ingot iron and steel

page_text: as manufactured by the basic Bessemer process, and has for its object rendering
silicious pig iron suitable for treatment in the basic converter.
Many varieties of pig iron are too high in silicon and too low in phosphorus to be
economically treated in the basic process, and it is to such varieties of pig iron that
my invention is more particularly applicable. It is often more economical for the
blast furnace manager to make a pig iron higher in silicon than is generally used in
basic Bessemer practice than to make a suitable basic pig iron, and the danger of
high sulphur is less with the former than with the latter variety.
To the molten pig iron, which may contain quite a high percentage of silicon
I add a suitable quantity of some ferruginous phosphoric cinder, such as basic slag,
which I prefer should be in the molten condition when brought into contact with
the pig iron.
The silicon in the pig iron rapidly reacts upon the ferruginous cinder or slag,
oxidizing itself to silica at the expense of the oxides of iron and phosphoric acid
contained in the cinder, both of which are deoxidized and reduced into the molten
pig iron.
I apply this reaction in practice either by running some of the slag from a
previous charge, or some ferruginous cinder into the ladle containing the pig iron,
from whence both metal and slag may be run into the vessel, thus effecting a
thorough mixture of the two; or some basic slag may be retained in the vessel at
the completion of a blow, upon which the molten silicious pig iron may be run.
The vessel may be rocked to facilitate the reaction of the metal on the slag.
The resulting slag is best poured off before the blowing commences as it is usually
high in silica.
The reaction is the same when phosphoric ferruginous cinder, such as tap cinder,
is substituted for basic slag.
This cinder may be used in the solid state or may be previously melted in a
small cupola, or other convenient furnace, before adding it to the pig iron.
The pig iron resulting from this operation will be found particularly well suited
for conversion into steel by the basic Bessemer process, as both phosphorus and
manganese are increased in the pig, whilst silicon, and to a lesser extent, sulphur,
are decreased. I find that when a pig iron with one per cent. of silicon is treated
about 1 cwts. of cinder may be used per ton of pig iron, varying the amount added
as the silicon varies.
Having now particularly described and ascertained the nature of my said inven-
tion, & in what manner the same is to be performed, I declare that what I
claim is ;-
In the manufacture of steel by the basic Bessemer process, the preliminary
treatment of the pig iron to be employed substantially as and for the purpose
described.
Dated this 5th day of January 1893.