IMPROVEMENTS IN THE MANUFACTURE OF IRON AND STEEL, AND IN APPARATUS EMPLOYED THEREFOR.
Year: 1874

page_text: LETTERS PATENT to Andrew George Hunter, of Flint, North Wales,
for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF IRON AND
STEEL, AND IN APPARATUS EMPLOYED THEREFOR.'
"
Sealed the 4th August 1874, and dated the 25th May 1874.
PROVISIONAL SPECIFICATION left by the said Andrew George Hunter
at the Office of the Commissioners of Patents, with his Petition,
on the 25th May 1874...
I, ANDREW GEORGE HUNTER, of Flint, North Wales, do hereby
declare the nature of the said Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF IRON AND STEEL, AND IN APPARATUS EMPLOYED THEREFOR," to
be as follows, that is to say:-
.
This Invention relates to the deoxidizing of iron ores and treating the
deoxidised products for the purpose of obtaining iron and steel. In one
form of apparatus this deoxidation is effected by means of carbon in
intimate contact with the iron ores at a red heat. In another form of
apparatus deoxidation is effected by means of carburetted hydrogen,
:

page_text: either alone or mixed with carbonic oxide or other deoxidising gases,
and with or without the aid of carbon mixed with the iron ore, which,
when being treated, is maintained at a red or higher heat. A suitable
form of the apparatus in which to reduce iron ores by carbon is a square,
oblong, circular, or other shaped chamber, closed at the bottom and top,
provided with openings at the top for the admission of ore and with
others at the bottom for its discharge, and with or without external
heating flues. The chamber contains one or more (according to the
sizes of the chambers and pipes) pipes of fire-resisting material open at
the top, but, as is also the case with the external heating flucs, not
extending entirely up to the under side of the roof of the chamber and
communicating at the bottom with a flue or flues to convey away the gases
from the said pipes and external heating flues, both pipes and flucs
being provided with valves or dampers to regulate heat. Near the tops
of these pipes and external flues, or near the top but below the roof of
the chamber, are openings provided with valves for the admission of air
and combustible gas.
The method of operating is as follows:-The iron ore in a crushed
or powdered state is mixed with carbonaceous matter in proportions
rather in excess of the quantity requisite to form carbonic oxide with
the oxygen present in the ore and charged into the closed chamber, caro
being taken that none enters the pipes or external flues. Combustible
gas and air are passed in a state of ignition through the pipes and
external flues, thus heating the mixture of iron ore and carbonaccous
matter, which involves carbonic oxide; this gas also finds an exit down-
wards through the pipes and flues and aids in maintaining the heat when
ignited on meeting the air.
When the mixture of iron ore and carbonaceous matter has been
maintained at a red heat for sometime a portion is withdrawn from. the
bottom, the whole mass sinks downwards, and the vacant space at top
is then supplied by a new charge of orc and carbonaceous matter. By
a repitition of withdrawals and renewals the process goes on continuously;
care being taken to so regulate the admission of combustible gas and
air as to maintain the mass in a red hot state. The length of time
necessary to deoxidize a given quantity depends partly on the fineness
with which the iron orc is crushed or powdered, and the consequent more
or less intimate mixture with carbonaceous matter, and partly on the
uniform maintenance of the heat, and also upon the refractory or other

page_text: "
nature of the iron ore used. By the term "combustible gas is meant
not only gas specially prepared for use but also any other available
source of waste or other licat.
A suitable form of apparatus in which to reduce iron ores by means
of carburetted hydrogen is a tower or shaft cither entirely unobstructed
in its interior space or provided with shelves, the iron ore in a crushed
state, and by preference finely ground and in a heated state being fed in
regularly at the top, and being met in its descent by an ascending
current of highly heated carburetted hydrogen, cither pure or containing
carbonic oxide or other deoxidizing gases. The ore arrives at the bottom
of the shaft in a deoxidized state and is removed from time to time.
:
The walls of the tower or shaft may be heated externally, and for
this purpose the gases leaving the top of the shaft may advantageously
be employed, their perfect combustion being effected by the admission
of air at suitable points. The iron ore may or may not be mixed with
carbonaceous matter, and may be fed into the top of the deoxidizing
tower in a heated state. A convenient mode of licating the orc is by
passing it down through a plain unobstructed tower, or through a tower
provided with shelves, being met in its descent by an ascending current
of highly heated gas or flame, and for this purpose the gases evolved
from the deoxidizing tower when mixed with air are suitable. A con-
venient arrangement is to make the heating tower an upward con-
tinuation or part of the deoxidizing tower, the respective limits of cach
being defined by the point at which air is admitted to burn the
carburetted hydrogen and other deoxidizing gases, and these limits
may be readily varied by having air pipes at different levels provided
with valves by which air can be admitted where desired, or the heating
tower may be arranged side by side, or in any other convenient position
with reference to the deoxidizing tower, the heated iron ore being
delivered at the top of the deoxidizing tower by suitable clevators.
The heating tower may have external heating flues, down which the
gases evolved from the top of the said tower may be passed, together
with such other heating gases or waste heat as may be necessary or
convenient.
The carburetted hydrogen and other deoxidizing gases may be heated
by passing them through a system of heating pipes, or through chambers
of brickwork or other convenient apparatus for heating gases, and as a

page_text: source of heat; for this purpose the gases, or part of them, evolved
from the deoxidizing tower may, when mixed with air, be employed.
The flues leading from the deoxidizing and heating towers are provided
with dust chambers for the deposition therein of the iron ore dust
mechanically carried off by the currents of gases, and also with dampers
or valves to regulate the heat and currents of gases. By either of which
apparatus and process of deoxidizing, herein-before described, the orc is
treated; when deoxidized it is, if removed in a hot state, placed in air-
tight boxes or waggons, in which if desirable a little tar, pitch, grease,
or other cheap inflammable substance has been previously placed in order
by its flame and smoke to expel free oxygen from the interior of the
box or waggons, and thereby prevent oxidation of the iron sponge.
The iron sponge may have been allowed to cool before removal from the
deoxidizing apparatus, in which case the use of air-tight boxes or
waggons is unnecessary, or it may be allowed to cool in the air-tight
boxes or waggons, or it may be taken directly to a press in a hot state;
but whether allowed to cool or treated hot it is placed in a press sub-
jected to pressure, and thereby consolidated into blooms, thus facilitating
subsequent handling and reducing the amount of surface liable to be
exposed to oxidation. A hydraulic press capable of exerting a pressure
of from 400 to 600 tons, or upwards, will force the deoxidized ore or
iron sponge into a compact bloom, say, 6 inches diameter, and from
1 to 13 feet long, according to the length of chamber of the press.
These pressed blooms may then be reheated, shingled, rolled, or squeezed,
and treated as muck bars, or by preference used for conversion into stecl
by fusion with cast or pig iron in an open hearth steel furnace, for which
purpose they are well suited.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Andrew George Hunter in the Great Scal Patent
Office on the 20th November 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANDREW
GEORGE HUNTER, of Flint, North Wales, send greeting.
TT
11

page_text: our Lord One thousand eight hundred and seventy-four, in the 37th year
of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Andrew George Hunter, Her special license
that I, the said Andrew George Hunter, my executors, administrators,
and assigns, or such others as I, the said Andrew George Hunter, my
exccutors, administrators, or assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during the
torm 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 MANUFACTURE OF IRON AND STEEL, AND IN THE APPARATUS EMPLOYED
THEREFOR," upon the condition (amongst others) that I, the said Andrew
George Hunter, by an instrument in writing under my hand and seal,
should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, and causo
the same to be filed in the Great Seal Patent Office within six calendar
months next and immediately after the date of the said Letters
Patent.
NOW KNOW YE, that I, the said Andrew George Hunter, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by
the following statement, reference being had to the accompanying
Drawings and to the letters and figures marked thereon, that is
to say-
My said Invention relates to the deoxidizing of iron ores, and to
treating the deoxidized products for the purpose of obtaining iron and
steel therefrom. In one form of apparatus this deoxidation is effected
by means of carbon in intimate contact with the iron ores at a red heat.
In another form of apparatus deoxidation is effected by means of car-
buretted hydrogen, either alone or mixed with carbonic oxide or other
deoxidizing gases, and with or without the aid of carbon mixed with the
iron ore, which when being treated is maintained at a red or higher
heat.
And in order that my
v said Invention may be properly understood. I
And in order that my said Invention may be properly understood. I
5 now proceed more particularly to set forth the system, mode, or manner
in or under which the same is or may be used or practically carried into

page_text: effect, reference being had to the accompanying Sheet of Drawings, and
to the letters and figures marked thereon, that is to say:
-
On the Sheet of Drawings hereunto appended Figure 1 is a vertical
section, and Figure 2 a horizontal section on the line a, b, Figure 1, of a
furnace or apparatus constructed in accordance with my said Invention,
and which it is preferred to employ in deoxidizing iron ores by means of
carbon in intimate contact with the said ores at a red heat. As shown
by these Figures the apparatus consists of a chamber A, which may be
square, oblong, circular, or of other shape, closed at its upper and
lower ends, and provided witli hoppers B at its upper end, through
which the orc is charged into the interior of the chamber A. A con-
venient size of chamber is 30 feet high, and 12 feet diameter or square.
The chamber A consists of an inner and outer casing or walls, the
former of which is terminated short of the upper end of the apparatus,
and between it and the outer casing side flues C extend downwards to a
flue D, as shown at Figure 1. The chamber A contains a series of
pipes E, open and terminated at the top at or about the level of the
height of the inner casing or wall of the chamber, from whence
they extend downwards and communicate at their lower ends, which
are also open with the flue D. The pipes E may be of various sizes;
a convenient size is from 4 to 6 inches in diameter, and set about
4 inches apart from each other, and they may be composed wholly
of fire-clay or other fire resisting material, or their upper parts may
be made of fire-clay and their lower portions of cast iron, or the pipes
may be made entirely of cast iron, and with or without stiffening ribs or
flanches extending partially or throughout their entire lengths. The
flues C (and also the pipes E if desired) are provided with valves or
dampers e to regulate the passage through them of the products of com-
bustion and other gases generated within the chamber A. Pipes or
passages G and F, provided with dampers or valves a, b, are situate at
the upper end of the apparatus, as shewn, through which combustiblo
gases and atmospheric air, either or both of which may if desired be
'previously heated, are separately conducted into the interior of the
chamber A, wherein they are admixed and ignited, an air pipe being
provided in conjunction with cach gas pipe, as shown.
of the chamber A is inclined from the centre towards the sides I thereof,
whereat exit pipes or passages I', provided with valves or dampers J, aro
situate for the outward passage of the iron ores after being treated in
The bottom H

page_text: the chamber A. The pipes or passages I¹ may or may not also be pro-
vided with jackets c, through which cold water or other cooling medium
may be made to circulate, and so cool the ores discharging through the
pipes or passages I'. On the Drawing two such pipes or passages I' àre
shewn, but any other suitable number of such exits, situate either on
one, two, three, or on all sides, or at several points of the circumference
of the chamber A, may be employed for the outward passage of tho
ores.
When two exit passages I' are adopted it is preferred, besides inclining
the bottom from the centre towards the sidos I, to also give the bottom
a dip or inclination from the sides K, Figure 2, towards the exits I',
which dip, or inclination may be in tlie form of an inclined plane, an arc,
or other similarly suitable figure, or other equivalent means may be
adopted for directing the whole of the ores to the exits I'; for example,
working holes arranged to permit the passage of tools but to exclude air
may be employed in the sides of the chamber A for that purpose; or if
the chamber A is circular the bottom H may be conical, sloping from.
the centre or apex downwards to the sides and outlet for the ores; or if
desired the outlet pipe or pipes I¹ may be fixed in the bottom H of the.
chamber A, passing through the fluc D. In this case the bottom II
should be inclined from the side I and K, or from the circumference
downwards towards the said outlet pipes.
The mode of working with the apparatus is as follows:-The iron ore
in a crushed or powdered state is mixed with carbonaceous matter
(preferably free from sulphur and phosphorus) in proportions rather in
excess of the quantity required to form carbonic oxide with the oxygen
present as oxide of iron and other easily deoxidized substances in the
ore, and charged into the closed chamber A through the hoppers B, care
being taken that none of the material enters the flues C or pipes E.
Combustible gas and air, either or both of which may, if desired, have
been previously heated, are then directed through the pipes G and F into
the chamber A, and meeting therein at the nozzles or twyers d arc
inflamed, and thereafter pass into a state of ignition downwards through
the flues C and pipes E, thus heating the mass of iron ore and carbona-
ceous matter in the chamber A; the iron orc is thereby deoxidized and
carbonic oxide is evolved. The carbonic oxide rises through the mass of
iron ore and carbon, and on reaching the surface whereat it is. ignited.

page_text: finds an exit downwards through the pipes E and flues C, and so aids in
maintaining the heat with the chamber A.
The mode of heating may be varied without departing from my said
Invention by causing the heating gases to pass upwards through the
pipes E, and downwards through the flues C, or vice versa, the necessary
alterations in the position of the gas and air inlets and in the connecting
and exit pipes and flues being made to suit the special modification
preferred, but the mode herein described is generally convenient and
economical.
When the mixture of iron ore and carbon has been maintained at a
red heat for a sufficient length of time a portion thereof is withdrawn
through the exits I', whereon the whole mass sinks downwards, and the
vacant space at the top of the chamber is then filled up with a fresh
quantity of admixed, crushed, or powdered iron ore and carbonaceous
matter. The process may in this manner be carried on continuously,
care being taken to so regulate the admission of air and combustiblo
gas as to maintain the whole mass being treated at a red heat.
The length of time necessary to deoxidize a given quantity of iron ore
in the apparatus hercin-before described depends partly on the fineness
into which it is crushed or powdered, and consequent more or less
complete or intimate admixture with the carbonaceous matter, and
partly on the uniform maintenance of the red heat, and also upon the
refractory, close, porous, or other nature of the iron orc used.
When it is desired not only to deoxidize the iron ore but also to
partially carburize the resulting iron sponge it is necessary to use a
greater excess of carbon, to employ a higher red heat, and to permit the
mass to remain exposed to the said heat during a longer period of time
than when simple deoxidation only is required. The quantity of carbon,
the degree of heat, and the length of time during which the iron ore is
exposed to the heat depends not only on the degree of carburation
desired but also, as in simple deoxidation, on the degree of fineness to
which the ore is powdered or crushed, and on its refractory, close, porous,
or other nature, this being largely influenced by the nature and amount
of the "gangue" or impurities contained in or associated with the ore.
The term "combustible gas
" herein-before made use of is meant not
only to refer to gas specially prepared in a gas generator, but also to

page_text: downwards to the said exit passages instead of, as shewn in the Drawing,
from the centre of S downwards to the exit passage K at the sides C.
Heat may also be imparted to the iron ore within the operating or
working chamber of the tower or shaft by the gases after leaving the
the said chamber, being conducted downwards through the flue or
flues B, wherein the perfect combustion of the heated gases is promoted
by air (heated or cold) admitted through the pipes or passages I. The
iron ore previously to being passed into the deoxidizing apparatus now
under reference may or may not be admixed with carbonaceous matter.
A convenient mode of heating the iron ore previous to passing it
into the deoxidizing tower or shaft is to pass the ore down through a
plain unobstructed tower or through a tower provided with shelves,
wherein it is acted upon in its descent by an ascending current of highly
heated gas or flame, and for this purpose the gases evolved from the
deoxidizing tower when mixed with air are suitable.
Under another arrangement (which is also indicated at the same
Figure 3 of the Drawings) the heating tower is made to constitute the
upper part of the deoxidizing tower, the respective limits of each being
defined, for the time being, and being capable of variation at the
pleasure of the operator by the point or level at which air is admitted
through the pipes H to the interior of the working chamber of the
tower to burn the ascending carburetted hydrogen and other gases; or in
lieu of such arrangement the heating tower may be placed side by side
or in any other convenient position relatively with the deoxidizing tower,
and it may be provided with heating flues similar to those shown at B,
Figure 3, down through which the gases evolved from the top of the
said tower are caused to pass together with such other heating gases or
waste heat as may be necessary or convenient.
The carburetted hydrogen and other deoxidizing gases are heated
before passing into the deoxidizing tower by conducting them through a
system of heating pipes or through heating chambers of brickwork or
other refractory material, or through other convenient apparatus for
heating gases; and as a source of heat for heating the apparatus through.
which the carburetted hydrogen and other deoxidizing gases are passed,.
the waste gases, or part of them, passing from the deoxidizing tower.
when admixed with air may be employed,
•

page_text: The flue O situate underneath the deoxidizing and ore heating tower,
and with which the flue or flues B communicate, as shewn, also acts as
a dust chamber wherein the iron ore dust mechanically carried off from
the operating chamber of the towers by the ascending current of gases
is deposited and may be removed from thence, as desired.
When it is desired not only to deoxidizo the iron ore in the tower or
sliaft shown at Figure 3 of the Drawings, but also to partially carburize
the resulting iron sponge a quantity of carbonaceous matter is admixed
with the iron ore previous to passing it down through the tower or shaft,
and the mass of carbon and iron ore is permitted to remain at the
bottom of the tower for some time, exposed to the heat of the current of
highly heated carburetted hydrogen passing into the tower through the
pipes J, thereby affording time for the carbon to penetrate or combine,
and thereby carburize the iron sponge. The time required for this
operation depends not only on the degree of carburation desired, but
also on the fineness of the iron sponge, the heat to which the sponge is
exposed, and the refractory, close, porous, or other nature of the ore
under treatment; a full red heat will usually be found to yield good
results, both in deoxidizing and carburating.
The iron ore deoxidized, and if desired carburized, in either of the
apparatuses or by either of the modes herein-before described may be
removed in a hot state from the apparatus, and placed in air-tight boxes
or wagons in which a quantity of tar, pitch, grease, or other inexpensive
inflamable substance has been previously placed, in order by its flame
and smoke to expel free oxygen from the interior of the box or wagon,
and thereby prevent rcoxidation of the iron sponge. Or the iron sponge
may be allowed to cool before being removed. from the deoxidizing
apparatus, or it may be cooled whilst passing through tho exit pipes K
by providing the said pipes with jackets, through which cold water is
O made to circulate as hercin-before described, in which case the use of air-
tight boxes or waggons is unnecessary. The iron sponge may also be
allowed to cool in the iron boxes or wagons themselves. Whether
allowed to cool or treated whilst still hot the iron sponge is subjected to
pressure, and thereby consolidated into blooms thus facilitating
5 subsequent handling thereof, and at the same time reducing the amount
of surface liable to reoxidation. An hydraulic or other suitable press
may be used to press the iron sponge into blocks of suitable forms, it

page_text: being understood however that I do not claim such pressing of the iron
sponge into blocks, as forming part of my present Invention.
The pressed blooms may be reheated, repressed, shingled, rolled, or
squeezed and treated as "muck" or "puddle" bars, or by preference
they may be used for conversion into steel by fusion with cast or pig
iron, or if sufficiently carburized by fusion alone in an open hearth
steel furnace with the addition of spiegel eisen or ferromanganese, for
which purpose the said blooms are well suited.
Having now described and particularly ascertained the nature of my
'said Invention, and the system, mode, or manner, in or under which the
same is or may be used or carried out in practice, I would observe in
conclusion that what I consider to be novel and original, and therefore
claim as the Invention secured to me by the herein-before in part recited
Letters Patent is,―
First. The arrangement and construction of apparatus illustrated at
Figures 1 and 2 of the appended Drawings, or modified as herein-before
explained wherein the deoxidation of iron ores, and if desired their
subsequent carburation by means of carbon in intimate contact or
admixture therewith is effected in a close chamber, heated by the ignition
of combustible gases and atmospheric air, and constructed with internal
flues and pipes, through which the carbonic oxide evolved in reducing
the iron ores or oxides, together with the other heated products of
combustion pass, and are so utilized as a source of heat, substantially
as herein-before described.
Second. The close, plain, or unobstructed towers or shafts, and the
employmeut thereof in the separate heating and deoxidation, and if
desired the carburation of iron ores or oxides alone or admixed with
carbon, by means of highly heated carburetted hydrogen alone or in
admixture with carbonic oxide or other reducing gases, substantially as
herein-before described in reference to Figure 3 of the Drawings hereunto
appended.
Third. The combined iron ore heating and deoxidizing tower or shaft
either constructed plain or partially or fully provided with shelves or
other obstructions, and wherein the respective limits of the heating and
dcoxidizing portions are or may be variable and defined by the point or
points at which air is admitted to the interior of the shaft, and the

page_text: employment thereof in the heating deoxidation, and if desired the
carburation of iron orcs or oxides alone or mixed with carbon, by
means of highly heated carburetted hydrogen alone or in admixturo
with carbonic oxide or other reducing gases, substantially as herein-
before described in reference to Figure 3 of the Drawings hereunto
appended, it being understood that it is not intended to claim the shelves
as an essential feature of this Invention.
employment thereof in the heating deoxidation, and if desired the
carburation of iron ores or oxides alone or mixed with carbon, by
means of highly heated carburetted hydrogen alone or in admixturo
with carbonic oxide or other reducing gases, substantially as herein-
before described in reference to Figure 3 of the Drawings hereunto
appended, it being understood that it is not intended to claim the shelves
as an essential feature of this Invention.
In witness whereof, I, the said Andrew George Hunter, have here-
unto set my hand and seal, this Ninth day of November, One
thousand eight hundred and seventy-four.
ANDREW GEORGE HUNTER. (L.S.)