Improvements in the Manufacture of Steel and Ingot Iron.
Year: 1893

page_text: Date of Application, 15th Mar., 1893
Complete Specification Left, 15th Dec., 1893-Accepted, 20th Jan., 1894
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Steel and Ingot Iron.
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 steel and ingot
iron, especially when such manufacture is carried out in basic lined furnaces or
converters either by the Bessemer or open hearth process and has for its chief
object increasing as much as possible the yield of ingot iron or steel per ton of
pig iron converted.
When employing briquettes of iron oxide and carbon as described in the
Specifications of the Letters Patent granted to me and numbered 5084 of the
year 1888 and 12500 of the year 1889, only a limited quantity of oxide can be
added during a charge as the amount of heat consumed in effecting the reduction
of the iron from the oxide is considerable and speedily cools the charge.
Also when adding oxide of iron to the charge, without previous admixture with
carbon, to hasten the removal of the metalloids contained in the pig iron to be
converted whilst simultaneously increasing the yield, the amount of oxide that can
be safely used is comparatively small.
I have found however that the amount of iron that can be added to the bath of
steel or ingot iron by the direct reduction of iron from its oxide may be very much
increased by the following method of procedure :-
I form briquettes of carbon and any suitable oxide of iron or ferruginous cinder
in such proportions that after a preliminary heating sufficiently intense to reduce
the oxide to metal, the resulting briquette will contain at pleasure either an excess
of oxide or an excess of carbon. These briquettes I add to the charge of pig iron
to be converted into steel either in the converter or furnace in which the conversion
is effected, or into the cupola or mixer prior to its introduction into the converter
or furnace.
At the commencement of a charge, when the bath of metal is high in carbon,
silicon and phosphorus (in basic working) I add as large quantities as possible of
the semi-reduced briquettes in which the oxide of iron is in excess; both the
excess of oxide and the reduced sponge of iron with which it is intermingled
sinking into the bath & speedily becoming reduced.
When however the carbon has been nearly removed from the bath, and especially
when there is still phosphorus left in the metal, the briquettes containing excess of
carbon are used. By this means the afterblow in the basic Bessemer process can
be very largely diminished, and the consequent waste of iron avoided. In the
basic Siemens process also I find these bricks containing excess of carbon and
reduced iron can be very advantageously added when the carbon in the charge to
be converted has been removed too quickly and phosphorus is still present in the
bath. They also enable a pig iron considerably higher in phosphorus to be used
without the excessive addition of hæmatite pig iron towards the end of the
operation for the purpose of removing the last of the phosphorus from the bath.
The ferro or spiegel used as finishing material can also be very largely replaced by
such briquettes holding excess of carbon.
For the purpose of getting a briquette of a definite composition as regards
excess of carbon I prefer to make them in iron moulds, such as waste galvanized
pans etc., but they can also be made in an ordinary press.
Dated this 14th day of March 1893

page_text: Improvements in the Manufacture of Steel and Ingot Iron.
I, THOMAS TWYNAM of Egham Hill, Egham in the County of Surrey
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 steel and ingot
iron, especially when such manufacture is carried out in basic lined converters and
open hearth furnaces, and has for its object increasing as much as possible the yield
of ingot steel per ton of pig iron converted.
When employing briquettes of iron oxide and carbon, as described in the
Specifications of Letters Patent granted to me and numbered 5084 of the
year 1888, and 12500 of the year 1889, only a limited quantity of oxide can be
added during a charge or "blow," as the amount of heat consumed in effecting the
reduction of the iron from the oxide is considerable and speedily cools the charge
of metal. Also when adding oxides of iron to the charge without previous
admixture with carbon, in order to hasten the removal of the metalloids contained
in the pig iron to be converted, whilst simultaneously increasing the yield, the
amount of oxide that can safely be used is small.
I have found however that the amount of iron that can be added to the bath of
steel or ingot iron by the direct reduction of iron from its oxide be
may
much
very
increased by the following method of procedure ;-
I form briquettes of carbon and any suitable oxide of iron or ferruginous cinder,
in such proportion that, after a preliminary heating, sufficiently intense to reduce
the oxide to metal, the resulting briquettes will coutain at pleasure, either an
excess of oxide, or an excess of carbon.
For briquettes intended to contain excess of carbon, at least 40 per cent. of carbon
should be present in the mixture of oxide and carbon before reduction. A very
suitable briquette can be made from 100 parts of small caking coal and 30 parts of
fine iron ore, such as purple ore; this can be conveniently reduced in any ordinary
coke oven.
Briquettes to contain excess of oxide after reduction, should not have more than
20 per cent. of carbon mixed with the oxide before reduction: these bricks are
most conveniently coked in moulds, as they are apt to break up on handling.
These briquettes I add to the charge of pig iron to be converted into steel either
in the converter or furnace in which the conversion is effected, or in the cupola or
"mixer" prior to its introduction into the converter or furnace. At the com-
mencement of a charge, when the bath of metal is high in carbon, silicon &
phosphorus, I add as large quantities as possible (having regard to the heat of the
bath) of the reduced briquettes in which oxide of iron is in excess; both the excess
of oxide, & the reduced sponge of iron with which it is intermingled, sinking into
the bath & speedily becoming reduced.
When however the carbon has been nearly removed from the bath, and especially
when there is still phosphorus left in the metal, briquettes containing excess of
carbon are used.
By this means the afterblow in the basic Bessemer process can be very largely
diminished, and the consequent waste of iron avoided.
In the basic Siemens process also I find these bricks containing excess of carbon
& reduced iron can be very advantageously added when the carbon in the charge
to be converted has been removed too quickly and phosphorus is still present in the
bath. They also enable a pig iron considerably higher in phosphorus to be used
without excessive addition of hematite pig iron towards the end of the operation,
for the purpose of removing the last traces of phosphorus from the bath.

page_text: The ferro or spiegel used as finishing material can be also very largely replaced
by such reduced briquettes containing excess of carbon.
Having now particularly described & 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 ingot iron or steel, the method of increasing the yield of
steel produced per ton of pig iron converted, by the use of previously reduced
briquettes containing either excess of carbon or excess of iron oxide substantially
as described.