IMPROVEMENTS IN THE PRODUCTION OF IRON AND STEEL, AND IN APPARATUS EMPLOYED THEREIN.
Year: 1875

page_text: LETTERS PATENT to Henry Larkin, of Theydon Gernon, in the
County of Essex, for the Invention of "IMPROVEMENTS IN THE
PRODUCTION OF IRON AND STEEL, AND IN APPARATUS EMPLOYED THEREIN.'
"
PRODUCTION OF IRON AND STEEL, AND IN APPARATUS EMPLOYED THEREIN.
"
Office of the Commissioners of Patents, with his Petition, on the
27th March 1875.
I, HENRY LARKIN, of Theydon Gernon, in the County of Essex, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
THE PRODUCTION OF IRON AND STEEL, AND IN APPARATUS EMPLOYED THEREIN," to
be as follows:-
In carrying out the method for the production of iron and steel
directly from the ore, as set forth in the Specifications of certain Patents
dated the 8th day of October, 1872, and the 8th day of April, 1873, and
numbered respectively 2964 and 1302, I greatly facilitate the reduction
of the powdered ore into powdered or spongy metal by the following

page_text: arrangement of furnace:-I place horizontally, and side by side, any
convenient number of D shaped fire-clay retorts or fire-brick ovens
similar to those used in an ordinary gasworks, but preferably much
lower in the crown, and heat them from a common furnace or gas
producer. These retorts are supported on a firm brickwork foundation
by a number of fire-clay bearers or bricks placed so closely together as
only to allow sufficient space anywhere between them for the free
passage of the heated gases from the furnace or gas producer. These
bearers are placed longitudinally and crosswise under the retorts in such
a way as to give the greatest available sustaining surface to the heavy
load of metal which the retorts are required to bear, and also to distribute
the heated gases as equally as possible to the whole of the under surface
of the retorts. Each retort is arched over with brickwork built up from
the brick foundation so as to form with the spaces underneath a separate
fluc surrounding cach. Divisional walls of brickwork are also carried
alternately across the upper and the lower half of the fluc to further
direct the current of heated gases, and to cause them to pass alternately
under and over the retort, and so to completely envelope it. Four
retorts may thus be conveniently arranged on the same level, side by side
with a common furnace to heat them, two retorts being placed on each
side of the furnace chamber.
The furnace consists of a rectangular chamber, with fire-bars and ash-
pit below, and two flues branching right and left to the two pairs of
retorts, the furnace chamber extending upwards into a large closed
hopper capable of being opened periodically for the admission of fuel.
Under the fire-bars a copious jet of steam or water is introduced,
in order by the decomposition of the steam as it passes through the
incandescent fuel to increase the quantity of gas generated and passed
onwards around the retorts. Air holes are also provided along the
tops of the flues surrounding the retorts in order to admit regulated
quantities of air to complete the combustion of the gases.
The retorts are open at each end, but are fitted with doors which may
be tightly closed. Thus one end of the retort may be open for charging,
and the other end for discharging and for obtaining access to the interior.
To the discharging end of the retort is attached an iron end piece, to
which is fitted an additional under door, through the opening of which,
when the door is removed, the discharged material may fall into a
receiver placed below.

page_text: The whole set of retorts is also connected by means of tubes so
arranged that by the aid of valves to be opened or closed as required the
gas evolved from any one retort, or any additional supply of gas intro-
duced into it from without, may be made to pass in succession through
all the others before finally escaping into the atmosphere.
In preparing the material to be reduced the ore is taken in a powdered
condition and intimately mixed in a revolving eccentric cylinder, as
described in the Specification of the Patent dated the Eighth of April,
1873, No. 1302, with regulated proportions of powdered charcoal and of
powdered resin, wood, pitch, or other suitable bituminous material. The
mixture is then heated sufficiently to soften the bituminous matter when
it is pressed into bricks or cakes in any suitable brick-pressing machine.
These bricks are packed closely on iron plates of any convenient length,
and of the width of the interior of the reducing retorts. When a retort
is empty and ready for charging, the charging end being open, the first
charge of bricks is pushed into the retort with the iron plate still under
them. At the back end of the plate is a vertical pin to slip into an eye
at the end of a long iron rod, by which it is pushed to the extreme end
of the red hot retort. A second rod having a broad cross piece at the
end is then introduced and pushed firmly against the bricks, while the
plate is pulled out from beneath them. A second and third charge arc
then similarly introduced until the retort is sufficiently filled. The
retort is then quickly closed, and the gas and volatile matter copiously
evolved from the heated resin is made to pass through the other retorts
containing heated material in a more advanced state of reduction.
When a charge is ready to be removed from a retort an iron receiver
is placed closely under the discharging end, the under door having been
removed for the purpose, and a supply of carburetted hydrogen or other
suitable deoxydising gas is introduced into that end of the retort suffi-
cient to cause an outward pressure, and so prevent all ingress of
atmospheric air, the supply of gas being kept up until the reduced
material is discharged into the receiver. When all is thus arranged the
door from the opposite or charging end of the retort is quickly removed
and a temporary door with a wide slot half way down the centre of it is
put in its place. The slot is for the introduction of the discharging
tools, by which the red hot metallic powder is pushed forward into the
receiver. It also allows the workman to sec into the retort. A second

page_text: supply of deoxydising gas is also at the same time introduced into this
charging end of the retort, so that both ends, although partially open,
are practically sealed from the atmosphere. As soon as the retort is
empty the gas at both ends is turned off and the receiver is removed and
kept carefully closed until its contents are cold, the under door is then
tightly shut and the retort is ready for another charge to be introduced,
as already described.
In preparing reduced iron powder for melting into steel or welding
into iron I mix it, as in the former case, with a sufficient quantity of
bituminous powder to cause it to cohere, and heat and press it similarly
into cakes. Should a larger proportion of carbon be needed I add
powdered plumbago in preference to charcoal, as it is less bulky and less.
readily burnt out. When using ores containing an excess of silica I
lessen the cutting effect of the slag upon the crucibles during the
operation of melting by mixing with the powdered material either before
or after reduction a regulated proportion of powdered banxite or of
emery, these minerals containing a very high percentage of alumina
mingled with oxide of iron. Before so mixing them with the powdered
material after its reduction I remove the oxygen from the iron by
intimately mixing the powdered mineral with bituminous powder, and
then pressing into bricks and reducing in the furnace, as already
described in the case of the ordinary ore.
SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said Henry Larkin in the Great Seal Patent Office on
the 25th September 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, HENRY
LARKIN, of Theydon Gernon, in the County of Essex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-seventh day of March, in the
year of our Lord One thousand eight hundred and seventy-five, in the 3
thirty-eighth year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Henry Larkin, Her special
license, that I, the said Henry Larkin, my executors, administrators,
2

page_text: and assigns, or such others as I, the said Henry Larkin, my executors,
administrators, and assigns, should at any time agree with, and no others,
from time to time and at all times thereafter during the term therein
expressed, should and lawfully might make, use, exercise, and vend,
within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN THE
PRODUCTION OF IRON AND STEEL, AND IN APPARATUS EMPLOYED THEREIN," upon
the condition (amongst others) that I, the said Henry Larkin, my
exccutors or administrators, by an instrument in writing under my,
or their, or one of their hands and seals, should particularly describe
and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the
Great Seal Patent Office within six calendar months next and imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Henry Larkin, do hereby declare
the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by
the following statement thereof, that is to say :-
This Invention has for its object improvements in the production of
iron and steel, and in apparatus employed therein.
In carrying out the method for the production of iron and steel
directly from the ore, as set forth in the Specifications of certain Patents
dated the 8th day of October, 1872, and the 8th day of April, 1873, and
numbered respectively 2964 and 1302, I facilitate the reduction of the
powdered ore into powdered or spongy metal by the following arrange-
ment of furnace:-I place horizontally, and side by side, any convenient
number of D shaped fire-clay retorts or firc-brick ovens similar to
those used in an ordinary gasworks, and heat them from one common
furnace or gas producer. An arrangement of four such retorts is
shown in Sheets 1, 2, and 3, a, a, being the retorts and 6 the furnace or
gas producer. These retorts are supported on a firm brick foundation
c, c, by a number of fire-clay bearers or bricks d, d, Sheets 1 and 3,
placed so closely together as only to allow sufficient space anywhere
between them for a free passage of the heated gases from the furnace or
gas producer. These hot-air spaces or flues e, e, are shewn in Sheets 1
and 3. The bearers d, d, are placed longitudinally and crosswise under
the retorts in such a way as to give the greatest available sustaining
.

page_text: surface to the heavy load of metal which the retorts are required to bear
and also to distribute the heated gases as equally as possible to the whole
of the under surface of the retorts. Each retort is arched over with
brickwork built up from the brick foundation so as to form with the
spaces e, e, underneath a separate flue surrounding each. Divisional
walls of brickwork f, f, Sheets 1 and 3, are also carried alternately
across the upper and the lower half of the flue to further direct tho
current of heated gases and cause them to pass alternately under and
over the retort, and so to completely envelope it.
The furnace or gas producer & consists of a rectangular chamber with
fire-bars g, g, and ash-pit / below. Two flues, one of which i, i, is
shewn in Sheets 1 and 3, branch right and left from the furnace to the
two pairs of retorts, the furnace chamber extending upwards into a
large closed hopper k, which is fitted with a lid to be opened periodi-
'cally for the admission of fuel. Under the furnace a copious jet of
steam or supply of water is introduced in order, by the decomposition of
the steam as it passes through the incandescent fuel, to increase the
quantity of gas generated and passed onwards around the retorts. mis
a vessel for holding water and conveying it, both as steam and as hot
water, to the furnace and on to the bars. n is an ordinary water trough
placed underneath the furnace. Along the tops of the flues surrounding
the retorts air holes o, o, Sheet 3, are provided, through which regulated
quantities of air may be admitted to complete the combustion of the
heated gases. The whole of these air holes are connected together by
means of a space p, p, provided by means of a second arch of brick-
work over the retort, which second arch and intermediate space also
serve to lessen the loss of heat by radiation. Cold air being admitted
at each end of this covered space through the apertures p², p¹, becomes
thoroughly heated before passing through the air holes o, o. The covered
openings q, q, are for obtaining access to the air holes o, o, in order to
regulate the supply of air admitted through each of them.
The retorts a, a, are open at each end, but are fitted with doors which
may be tightly closed, and which are similar to those used in a gas
furnace. These doors are opened periodically for charging or dis-
charging and for obtaining access to the interior. To the discharging
end of the retorts are attached iron end picces, to which are fitted
additional under doors 7, 7, Sheets 1 and 2, through the opening of

page_text: which, when a door is removed, the material may fall into a receiver
placed below.
The whole set of retorts is connected by means of tubes 8, 8, Sheet 2,
so arranged that by opening or shutting the valve in each as required
the gas evolved from any one retort, or any additional supply of gas
introduced into it from without may be made to pass in succession
through all the others before finally escaping into the atmosphere.
The valves are usually so arranged as to allow the gas generated in
the retort last charged to pass in succession through the other retorts,
and finally to escape at the discharging end of the retort, which will
next be emptied. There is a peep hole in the cover of the retort which
may be left open, and the gas burns as it escapes from this aperture.
In preparing the material to be reduced the ore is taken in a powdered
condition and intimately mixed in a revolving eccentric cylinder, as
described in the Specification of the Patent dated the 8th of April, 1873,
No. 1302, with regulated proportions of powdered charcoal and of
powdered resin, wood, pitch, or other suitable bituminous material. The
mixture is then heated sufficiently to soften the resin or other material,
after which the whole is pressed into bricks or cakes in any suitable
brick pressing machine. A suitable mixture is obtained by adding to
the finely powdered ore from five to eight per cent. of wood, resin, and
charcoal dust in sufficient quantity, together with the resin, to reduce
the iron oxide to a metallic state. To introduce these bricks into the
red hot retorts a convenient weight of them is packed on an iron plate u,
Sheet 3, of the width of the interior of the retorts. When a retort is
empty and ready for charging, the charging end being open, the first
plateful of bricks is pushed into the retort with the iron plate still
under them. At the back end of the plate is a vertical pin to slip into
an eye at the end of a long iron rod w, by which it is pushed to the
extreme end of the red hot retort. A second rod w', having a broad
cross piece at the end, is then introduced and held firmly against the
bricks while the plate is pulled out from beneath them. A second and
third plateful are then similarly introduced until the retort is sufficiently
filled. The retort is then quickly closed and the gas and volatile matter
copiously evolved from the heated resin or other bituminous material is
made to pass through the other retorts containing heated material in a
more advanced state of reduction.

page_text: When a charge is ready to be removed from a retort, which is usually
after being exposed to a bright red heat for twenty-four hours an iron
receiver a, Sheets 1 and 3, is placed closely under the discharging end
piece, the under door having been removed for the purpose, and a
supply of carburetted hydrogen or other suitable deoxydising gas is
introduced into that end of the retort by means of the gas pipes y, y,
Sheet 2, sufficient to cause an outward pressure and so prevent all
ingress of atmospheric air, the supply of gas being kept up until the
reduced material is discharged into the receiver. When all is thus
arranged the door at the opposite or charging end of the retort is
quickly removed and a temporary door with a wide slot half way down
the centre of it is put in its place. The slot is for the introduction of
the discharging tools z, z, Sheet 3, by which the red hot metallic powder
is pushed forward into the receiver. It also allows the workman to
sce into the retort. A second supply of deoxydising gas is also at the
same time introduced into this charging end of the retort, so that both
ends, although partially opened, are practically sealed from the atmo-
sphere. As soon as the retort is empty the gas at both ends is turned
off, and the receiver a containing the red hot iron powder is removed
and kept carefully closed until its contents are cold. The under door r
is then tightly shut, and the retort is ready for another charge to be
introduced, as already described.
In preparing reduced iron powder for melting into steel or welding
into iron, as described in the Specification of the Patent dated the 8th of
October, 1872, No. 2964, I mix with it in place of an equivalent pro-
portion of powdered charcoal, a sufficient quantity of bituminous powder
to make it cohere after being heated. I prefer to employ from three
to five per cent. of wood resin. It is then pressed into cakes in a brick
press, as in the previous mixture, which cakes are in all cases much
more convenient to handle than the loose powder. I add manganese in
the process of melting, as is usual in the manufacture of cast stecl.
I employ a magnetic separating machine to remove impurities from
the deoxydised ore, and also when working with a magnetic oxide ore
to prepare the ore in the first instance. In this way I ensure a higher
degree of purity in the materials than would be otherwise attainable.
Having thus described the nature of my said Invention, and the
manner of performing the same, I would have it understood that I

page_text: claim, the means of and apparatus for the production of iron and steel,
substantially as described.
In witness whereof, I, the said Henry Larkin, have hereunto set
my hand and seal, this Twenty-third day of September, in the
year of our Lord One thousand eight hundred and seventy-
five.
HENRY LARKIN. (L.S.)