Improvements in the Reduction of Metallic Ores and in Apparatus therefor.
Year: 1890

page_text: Date of Application, 28th Jan., 1890
Complete Specification Left, 18th Oct., 1890-Accepted, 29th Nov., 1890
PROVISIONAL SPECIFICATION.
[Communicated from abroad by CHARLES ADAMS, Iron Manufacturer, of Pittsburgh,
in the County of Allegheny, State of Pennsylvania, United States of America.]
Improvements in the Reduction of Metallic Ores and in Apparatus
therefor.
I JOHN THOMSON KING of Liverpool in the County of Lancaster, Patent Agent,
do hereby declare the nature of this invention to he as follows:-
My invention relates to the reduction of metallic ores by means of a current of
heated gas such as carbonic oxide, and consists essentially in subjecting the ores to
the action of a horizontal or nearly horizontal stream or streams of heated reducing
gas or gases, moving in a continuous zig zag or other suitable path.
Apparatus under my invention consists of chambers or receptacles provided with
gas inlet and outlet ways and if desired with diaphragms partitions or other dividing
pieces so disposed that the heated reducing gas or gases is or are caused to travel
through the ore in a horizontal or nearly horizontal path or paths.
Further improvements consist in constructing the reducing apparatus with a
reservoir for receiving and containing the reduced ore and in combining the said
apparatus with an open hearth steel melting furnace when iron ores are being
reduced.
ind thi. 07.1.
1900
Per pro J. T. KING,
J. Johnson.
COMPLETE SPECIFICATION.
Improvements in the Reduction of Metallic Ores and in Apparatus
therefor.
I JOHN THOMSON KING of Liverpool in the County of Lancaster, Patent Agent,
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:-
My invention relates to the reduction of metallic ores by means of a current of
heated gas such as carbonic oxide, and consists essentially in subjecting the ores to
the action of a horizontal or nearly horizontal stream or streams of heated reducing
gas or gases, moving in a continuous zig-zag or other suitable path.
Apparatus under my invention consists of chambers or receptacles provided with
gas inlet and outlet ways and if desired with diaphragins, partitions or other dividing
pioces so disposed that the heated reducing gas or gases is or are caused to travel
through the ore in a horizontal or nearly horizontal path or paths.
Further improvements consist in constructing the reducing apparatus with a
reservoir for receiving and containing the reduced ore and in combining the said
apparatus with an open hearth steel melting furnace when iron ores are being
renced

page_text: Figure 5 is a view of a modification of the apparatus.
Figures 6, 7, and 8 show in vertical section other forms of the apparatus.
Like symbols of reference indicate like parts in each.
My invention relates to an improvement in that process of reducing metallic ores
in which the reduction of the ore is effected by passing through it a current of heated
reducing gas, such as carbonic oxide which deoxidizes the ore and reduces it to a
metallic condition.
The rationale of this process of deoxidizing metallic oxides is as follows:-In
acting on the oxides of iron, the carbon present in the reducing gas has at a red heat
such affinity for the oxygen combined with the metal in the ore that the latter element
will leave the iron to combine with the carbon of the reducing-gas changing the
carbonic oxide (C.O.) into carbonic acid (CO,).
If carbonaceous matter such as coke be intermingled with the ore, the second
equivalent of oxygen in the carbonic acid will take up an equivalent of carbon thus
returning to the condition of carbonic oxide, and thus revived will become once more
available as a reducing agent. If no carbonaceous matter be present in the mass of
ore, the oxydizing effect of the carbonic acid upon the metallic iron already pro luced
will eventually be remedied by the constant current of fresh gas, and the oxygen be
thoroughly eliminated from the ore.
In this process the chief requisite to its practice on a large scale and to its
commercial success, is that the reducing gas shall thoroughly permeate the mass of
ore under treatment, and shall pass therethrough in a current sufficient to present to
the ore, fresh gas to take the place of the gas continually undergoing the process of
conversion into carbonic acid.
The practical difficulties experienced in causing the gas to flow through the mass
of ore in sufficient volume to cause rapidly and thoroughly the desired re-action have
prevented hitherto the commercial success of the direct process of reduction above
described so that the expensive blast furnace process has been used almost universally
to convert the ore into pig-iron as a preliminary to its further treatment.
I have discovered that the difficulties of transmission of the gas through the ore
may be overcome and the direct process made practicable for use on a large scale by
giving to the gas a horizontal direction as contrasted with the vertical direction
heretofore sought to be given to it.
For example if two similarly charged cubical reducing chambers of like dimensions
be so arranged that the gaseous current will traverse the material in a horizontal
direction in one of them and in a vertical direction in the other, the force required to
drive or draw the gas through the material in a horizontal direction will be much less
than that required to drive or draw it through the material vertically. This discovery
I utilize by so constructing the reducing apparatus as to cause the passage of the gas
through the material to be either wholly in a horizontal direction or approximating
thereto as nearly as consideration of convenience in the construction and operation of
the apparatus will permit. In the claim I employ the expression" substantially
horizontal" to mean a direction exactly horizontal or one somewhat inclined, and
therefore approximately horizontal.
The discovery of the superior ease of movement of the gas through the material in
a horizontal as compared with a vertical direction, and the more iborough and more
rapid reduction of the ore thereby effected is of the greatest importance in iron
metallurgy. It renders easy of accomplishment that which has hitherto been striven
for in vain to wit the thorough permeation by the reducing gas of bodies of ore of
sufficient magnitude to render the quantity of the output large enough to make the
operation economically successful.
I am aware that reducing gas has been heretofore caused to pass in a more or less
horizontal direction through or over thin layers of ore and where passed through it,
the ore has usually been caused to move in a downward direction in body of small
thickness over gas passages; and also that reducing-gas has been introduced into one
end or side of a small reducing vessel or retort, having an opening at the other end or
side only, so that the gas has been forced to pass more or less horizontally through

page_text: the contents of the retort; but the problem which I have solved is materially different
from either of these being that of effecting the permeation of a large mass of ore with
the hot reducing gas in a kiln or reducing chamber, in which the reducing gas is not
necessarily compelled by the construction of the furnace to take either a horizontal or
vertical course in traversing the ore.
The horizontal as distinguished from the vertical passage of gas through the mass
of ore has always been regarded as very difficult and undesirable, but I have
discovered that it is in fact not only easy of accomplishment, but also the most
effective method of securing the intimate commingling of the gas with the particles of
ore. My improvement then consists in the application to the kiln process of reduction,
as distinguished from the retort process of the horizontal or substantially horizontal
passage of the gas through a mass of ore either by one or more separate transverse
passages, or by a series of substantially horizontal passages at progressively higher
levels as hereinafter described.
Many different forms of the apparatus may be devised for the practice of my improved
process.
I have shown in the drawings several constructions of apparatus which I deem
to be well suited for this purpose, and shall now proceed to describe the same,
premising that the process is not limited to the construction or form of the apparatus,
but relates broadly to my newly discovered and peculiar mode of passing the reducing
gas through the material under treatment.
I intend also to claim specifically the apparatus shown in Figures 1, 2, 3, 4, and 5
since it possesses many advantageous qualities.
In the drawings A is the furnace built of brickwork upon a foundation B which as
shown in the drawings is rectangular and oblong but may be circular, elliptical or other
convenient shape.
Suitable proportions to dimensions are a length ten times its width and a height
which will allow of the sufficient subjection of the ore to the reducing atmosphere, say
ten to fifteen times its width. These relative proportions however are not of the
essence of the inventions and are given merely as a statement of proportional size
which has been found successful in practice.
The interior of the furnace is furnished with checkerwork cc of firebrick, arranged
on each side and at the two ends of the furnace, as shown in Figures 2 and 3, the
checkerwork ce being so arranged (as shown in those figures) as to leave a clear
vertical space D from the top to the bottom of the furnace. In this space D the ore
is charged and is reduced. The space D is long and narrow as shown in Figure 3
and fapers upwards in width being marrower at the top than at the bottom, so as to
give the necessary clearance for the descent of the charge. This working space D is
closed at top by a covered hopper E which has besides its cover, at the bottom of the
hopper a hinged trap door e for the admission of the charge which is normally kept
closed by a weight wc. The working space D, is also closed at the bottom, either by a
removable door of ordinary construction, or preferably as shewn in the drawing,
(Figure 2) by being placed over a tightly closed reservoir F which forms part of the
foundation B. This reservoir F is the receptacle into which the reduced ore (iron
sponge) is discharged from the working space D of the furnace, and is provided with
one or more inclined shutes G, from which the reduced ore is removed from time to
time, double sliding doors bb being provided to each shute, so that one may be closed
when the other is opened so as practically to exclude the air from contact with the
hot sponge.
The checkerwork c, c', &c. in the interior of the furnace A is placed within a series
of separate chambers formed by the horizontal shelves or diaphragms H H', &c.
which extend from end to end of the furnace and from each side to the central
working space D but the diaphragms H on one side of the space D are not on the
same level as those H' on the opposite side (see Figure 2) the diaphragm H on one
ide being placed in a horizontal plane about midway between two diaphragmns H' on
he opposite side.

page_text: Below the furnace A are placed two regenerators K K¹ fitted with brick checker-
work L in the usual way.
These regenerators are connected by uptakes M with a horizontal flue N which
extends the whole length of the furnace and connects by numerous adits n with the
checkerwork 2 in the lowest checkerwork chamber of the furnace on one side as
shown in Figure 2. Valves P P¹ (preferably made of fireclay tile) are connected
with the flue N by which the regenerators K K' are alternately connected with the
checkerwork c in the lowest chamber in the interior of the furnace. A short
horizontal flue R connects the topmost of the checkerwork chambers c of the furnace
with a downtake or draft flue Q, which conveys the gas as it leaves the furnace down-
wards to one of the regenerators K, K', through the butterfly valve S which can be
set so as to admit the gas from the top of the furnace into either of the regenerators;
the valves P, P¹, and S being reversed from time to time so that when the
regenerator K¹, is in connection with the furnace, the other regenerator K, is
connected with the downtake flue Q and vice versa.
downtake determine the direction of the draft downwards from the top of the
A steam ejector T placed in the
furnace A to the regenerators and regulates its amount and velocity. A flue U
connects both of the regenerators K, K', with a stack or chimney to carry off the
products of combustion, and a valve u according as it is set connects one or other of
the regenerators with the flue and chimney.
The reducing gas by which the oro is to be reduced, may be either carbonic
oxide (CO) or hydrocarbon gas or vapor which is prepared in a separate gas producer
of any desired construction.
If carbonic oxide is used the common Siemens gas producer may be employed, if
hydrocarbon gas or vapor, it may be manufactured in any suitable apparatus, or may
be simply a vessel charged with petroleum or other liquid hydrocarbon and heated
sufficiently to vaporize it. V is a valve for admitting the carbonic oxide or hydro-
carbon gas or vapor from the producer to one or other of the regenerators K or K',
according as the valve V is set.
The spout of the shute G may be extended by a movable spout y (as shewn
in Figure 4) so as to conduct the hot sponge or reduced ore directly from the
reservoir F into the open hearth furnace W previously provided with a charge of
molten bath metal. The open hearth furnace W, being of any ordinary construction
of such apparatus and well known to those skilled in the art, needs no further
description here.
In case it is desired to dispense with the use of the regenerators K, K', a simpler
construction of my furnace may be used as shown in Figure 5.
I
The furnace itself with the working space D, partitions H H₁, and checker-
work c, c, placed in separate chambers, is the same as already described; but in
place of the regenerators K K' their flues and valves and flue N and openings n,
place underneath the furnace a pair of fireplaces X X, in which solid carbonaceous
fuel is consumed by slow combustion so as to produce carbonic oxide, which is
introduced into the lowest checkerwork chamber c through a flue c. In this case the
downtake is furnished with the ejector T, and the escaping gas from the top of
the furnace is conducted under the steam boiler to serve as fuel, or if preferred by
closing the valves Y and opening the valve Y¹ the gas will pass off to the stock or
through the pipe Z to be used for any purpose that may be desired. The operation
of the apparatus hereinbefore described as applied to the reduction of iron ores by a
direct and continuous process is as follows: When the furnace is first used, or when
first used after having been emptied of its charge of reduced ore, the lower portion of
the reservoir L is filled with kindling materials, on top of which coke is charged to or
nearly to the top of the working space D; the kindling is ignited, and the doors bb,
at the bottom of the reservoir, as well as the hoppers at the top of the working
space D, are opened wholly or partially, so as to secure the ignition and combustion
of the coke. When the working space is sufficiently heated, the air is shut off, and
the ore to be reduced is then charged into the working space D of the furnace through

page_text: the hoppers E, which by using the trap door e, will serve if desired as a measure of
quantity of the charge.
The ore before being introduced, may if desired have mixed with it a small quantity
of some carbonaceous solid such as coke, coal, charcoal &c. I have found it advan-
tageous to use for this purpose coke to the amount of 10 to 15 per centum by weight,
of the charge of ore. The working space D is filled with this charge from top to
bottom, and if a continuous process is desired, the working space is kept filled up with
ore (or ore and carbon) as the reduced ore gradually passes away below.
Before commencing the operation of reduction the regenerators K K' are both
heated to from 800 to 1200 degrees Fahrenheit. The supply pipe of the ejector T,
is connected with the live steam space of a steam generator, the hopper E is close.l, as
also the sliding doors in the shute of the reservoir F, so as to exclude as much as
possible the external atmospheric air from the interior of the furnace A and the
valves S P, and V are set so as to connect one regenerator (as K) with the flue N
and thus with the lower chamber c² of one side of the furnace A¹; the valve V is
set so as to connect the same regenerator K with the gas producer and the valve S is
set so as to connect the downtake Q from the top of the furnace with the other
regenerator K¹.
The apparatus being thus adjusted, the carbonic oxide from the gas producer enters
the flue and thence passes up through previously heated checkerwork in the
regenerator K and becomes thereby heated to a temperature of from 800 to
1200 Fahrenheit, and thence arises through the uptake M into the flue N and enters
the lowest checkerwork chamber c at one side of the furnace, through the adit n,
heating the checkerwork in the furnace as it traverses it; as the gas finds no passage
way upwards being obstructed by the partition or diaphragm H, it passes horizontally
through the mixed ore and carbonaceous matter at the lower end of the working
chamber D. Here its upward passage through the superincumbent charge of ore being
difficult, the gas following the path of least resistance, enters the lowest of the
chambers e', on the opposite side of the furnace. Here it rises through the checker-
work until it meets the obstruction of the first partition of that side of the furnace
which is at a higher level than the first partition on the other side, and is forced to pass
again horizontally into the charge of ore &c., in the working chamber D, and again
taking the path of least resistance it enters the checker work on the side of the furnace
at which it first entered, but into a chamber higher up, and thus owing to the
obstruction presented by the partitions H, H &c. on one side and H', H', on the other
side and to the position of the partitions on one side of the space D, being on a
different level from those on the opposite side, the reducing gas is compelled to
follow a zig zag course backwards and forwards horizontally through the column of
ore in the working spice D,and vertically and progressively through the chambers cc',
until it reaches the horizontal flue H, through which it enters the downtake Q and
passes down through the valve S set to conduct it into the other regenerator K.'.
Here the gas meets and combines with a current of atmospheric air admitted in any
desired and regulated quantity, to secure complete combustion, by means of the
valve communicating its heat to the checkerwork in the regenerator. The products
of combustion thence pass off through one of the flues U, and valve u to the stack or
chimney placed at any convenient point. The downward draft through the down-
take and consequently the upward current through the furnace A is secured and
regulated by the ejector T situate on the downtake Q.
In order to preserve the requirel uniform temperature of gas passing through the
furnace, the regenerator valves should be shifted every ten or fifteen minutes so as to
turn the supply gas from the producer into the regenerator which has just been
heated up by combustion of the escape gas from the top of the furnace, and thence
through the valve P and flue N into the bottom of the furnace and to change the
course of the escape gas from the top of the furnace through the downtake Q by the
valve S into the regenerator through which the supply gas has just been passing.
Any other means for heating the ingoing gas may be employed. For example
where the gas regenerator is capable of supplying the gas at a sufficient elevated

page_text: temperature, such generator may be so placed as to deliver the gas directly into
the flue N.
The reactions produced by this process are as follows: The heated reducing gas
(carbonic oxide) passing through the body of the ore in the working space D of the
furnace, effects the deoxidation of the ore. The oxygen liberated from the ore has a
tendency to combine with the carbonic oxide (CO) and form carbonic acid (CO₂) the
presence of which would arrest the deoxidation of the ore, but this tendency is
counteracted partly by the carbon when used mixed with the charge of ore, but chiefly
by the constant access from the gas-producer or source of supply to the interior of the
furnace of fresh carbonic oxide or hydrocarbon gas or vapor preheated by passage
through one of the regenerators, and by the heat of the furnace which is such, that
carbonic acid cannot exist in the presence of carbon. Furthermore the desired degree
and uniformity of temperature of the reducing gas is maintained within the furnace
by the heat communicated to and stored up by the checkerwork in the several
chambers of the furnace, which absorb and take up any excess of heat of the incoming
gas which may occur, as in case of the reversal of the valves turning the gas through
a freshly heated regenerator, and give out this stored up heat to the gas when its
temperature is reduced by the cooling of the regenerator previous to such reversal;
and thus by means of my improved process and the use of the apparatus herein
described, the reducing quality of the gas as well as the necessary uniform degree
of heat is maintained throughout the furnace and during its entire operation.
The result of my process, so far as described, is the production of deoxidized iron
ore properly called iron sponge. As this is formed without fusion, the pieces do not
adhere together but preserve very nearly the size and shape of the pieces of ore
charged into the top of the furnace. In consequence of the reducing gas passing
back and forth through the charge of ore repeatedly before it escapes at the top of
the furnace, and being unable to rise up directly through the charge the ore is much
more thoroughly treated than it can be in any other apparatus of which I have any
knowledge; and as the gas after each passage across the working space through the
ore is compelled to enter the checkerwork before returning through the ore its
temperature is regulated and rendered uniform as hereinbefore explained.
The iron sponge when produced drops down gradually into the receptacle or
reservoir E which extending under the entire length of the furnace will hold a large
amount of sponge. The doors bb being kept closed, the sponge is substantially pro-
tected from the excess of external atmospheric air which rapidly oxidizes the sponge
especially when in a heated condition.
My purpose is to continue the process to the extent of the manufacture of steel in
an open hearth, for which hot sponge made by my process is especially adapted. To
this end I locate the open hearth furnace W sufficiently near to the reservoir F for
the sponge while still red hot to be dropped down through the shute Q and a movable
spout connected therewith into the open hearth in which a previously prepared bath
of melted carbide of iron is awaiting the addition of deoxidized iron for its conversion
into steel.
The open hearth process as ordinarily practised is then carried out, with the
exception that care should be taken to turn off the supply of atmospheric air from the
furnace during the time when the hot iron sponge is being introduced into the hearth,
in order that the sponge may be, until it sinks under the surface of the metal
composing the bath, protected from the action of an oxidizing atmosphere and be
subjected only to one that is either carburizing or neutral. Otherwise the process so
far as the open hearth treatment is concerned is the same as usual, excepting that less
time is required for the melting of the sponge in the bath than is necessary for the
ordinary scrap or wrought iron additions.
I find it better to treat about two thousand pounds of sponge at a time in the
open hearth.
By my process taken as a whole as well as in each step by itself, the reduction of
the ore and the treatment in the open hearth are effected in a much shorter space
of time and with better results than by any other process with which I am acquainted.

page_text: I have described my process as applied to the reduction of iron ore by means of
carbonic oxide without the formation to any injurious degree of carbonic acid, and
with the continuous reduction to carbonic oxide of any carbonic acid that may be
formed. I have stated that the pro ess may be conducted with the use of carburetted
hydrogen gas, or of hydrocarbon vapor in which case substantially the same results
are produced. As in this case however, no oxygen is present in the reducing gas but
a larger proportion of carbon there is much less liability of the formation of carbonic
acid and a smaller proportion of carbon or none at all, is needed in the charge, but
the action of the carbon in deoxidizing the ore, and the preservation of an uniformity
of character and temperature of the reducing agent due to the construction of the
furnace are preserved.
In case the furnace is used without the regenerators, as shown in Figure 5, the com-
bustion of the carbonaceous fuel in the furnace is conducted with a limited supply of
air so as to produce carbonic oxide rather than carburetted hydrogen and fuliginous
matter. The apparatus thus constructed is simpler and cheaper than that shown in
the other figures, and can be used to great advantage, but it is more difficult to
preserve an uniform heat or an uniform quality and quantity of the reducing gas,
because every time the fire is stirred or fresh fuel is added to it, more fuliginous
matter is evolved, and the production of carbonic oxide is decreased.
By means of the apparatus constructed as above described. I am enabled to carry
the current of reducing gas horizontally back and forth through the column of
material performing the work of reduction in the most thorough manner and with
great rapidity, owing to the considerable height of the column of material under
treatment at one time.
In Figure 7 show another form of apparatus by which my invention may be
practised. The reducing chamber D is unprovided with the lateral checkerwork
chambers and diaphragms, such as are shown in Figure 1, but has lateral openings 2, 3,
which open into flues N N for the supply and discharge of the reducing gases,
The ore and coke are charged into the reducing chamber through the hopper E and
are removed at the base thereof through a drop bottom E. The flues N and N' may
he connected with regenerators as explained with reference to Figures 1 and 2,
or the fine N may be connected directly with the stack. The reducing gas enters
the chamber D through the holes 2, and after passing horizontally through the
body of the ore and coke, emerges through the holes 3, and passes off through the
flue K'.
By reason of this horizontal course of the gas, but comparatively little resistance
is afforded to its passage, and it may be introduced into the chamber in volume
large enough to effect with rapidity the desired reduction. It will be observed
however that as the gas passes through the body of ore but once and does not assume
a zig-zag or recurrent course, as in the use of the apparatus shown in Figures 1 and 2,
it does not come so thoroughly into contact with the particles of ore.
The apparatus
is therefore not so economical as that of Figures 1 and 2 and requires the use of a
greater quantity of gas, but in respect of the horizontal course assumed by the gas in
passing through the ore, it affords means by which my invention may be practised
fiiently and with good results.
The apparatus shown in Figure 6 is substantially the same as that shown in Figure 7,
except that the holes 2 and 3 are not precisely opposite to each other, but are
alternately arranged, so that the gas passes through the or not in exactly horizontal
lines, but in lines which though substantially horizontal are somewhat inclined. By
use of the apparatus the advantages of my invention are secured, although of course,
the greater the degree of deviation of the gas from a horizontal course the more
difficult is its passage and the less are the advantages of the invention obtained.
In the apparatus shown in Figure 8, the ore to be reduced is placed with its
carbonaceous addition in a vessel 4 which is removably set with the chamber of the
reducing furnace upon a bed of sand, and extends from end to end of the chamber.
The reducing gas enters the chamber through the flue N and traverses horizontally
the vessel 4 entering through holes 2 on one side and escaping through holes 3 on the

page_text: other side, finally passing from the chamber through the exit flue N. During the
process of reduction, air should be excluded from the vessel by means of a cover plate 5,
the edges of which may be luted with clay or sand. When the reducing process is
complete the vessel with its charge of iron sponge may be lifted from the furnace and
conveyed to the refining furnace, such as an open hearth furnace, where its treatment
is continued and completed as will be readily understood.
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 :-
1. In the art of reducing metallic ores, the improvement which consists in passing
the reducing gas in a substantially horizontal direction through the material under
treatment; substantially as and for the purposes described.
2. In the art of reducing metallic ores, the improvement which consists in passing
the reducing gas back and forth in a zig-zag progressive course through the
material under treatment, substantially as and for the purposes described.
3. In apparatus for reducing metallic ores by a gaseous reducing agent, a reducing
chamber for containing the material under treatment, said chamber having for the
admission of gas into the material and its discharge therefrom, opposite ports on
approximately the same horizontal plane; substantially as and for the purposes
described.
4. The process of manufacturing iron from the ore by placing the ore with or
without the admixture of solid carbonaceous material in a furnace wherein it is
surrounded by checkerwork arranged in separate chambers, introducing a reducing
gas into the checkerwork and forcing it to pass back and forth through the mass
of ore and into and out of the checkerwork on its passage through the furnace :
substantially as and for the purposes described.
5. The method of manufacturing iron and steel direct from the ore by a con-
tinuous process consisting of feeding the ore-with or without admixture of solid
carbon into and surrounding it with checkerwork within a furnace, introducing
heated reducing gas into the furnace and causing it to pass backwards and forwards
through the ore from checkerwork to checkerwork until the ore is deoxidized to
the condition of sponge, and passing it while hot into a bath of melted carbide of
iron in an open hearth furnace, and subjecting it therein to the usual open hearth
treatment, substantially as and for the purposes described.
6. A furnace for reducing oxide of iron consisting of an outside shell divided
internally by horizontal partitions into separate chambers and having a central
space for the reception of ore, the partitions being located at different levels on
opposite sides of the furnace connected at the lower end with apparatus for supplying
reducing gas and with an opening for the discharge of the reduced ore and at the
upper end with a charging hopper and exit flue for the escape of the waste gas,
the charging and discharging openings being provided with devices for the exclusion
of the external atmosphere; substantially as and for the purposes described.
The combination with a pair of checkerwork regenerators, and a source of
supply of reducing gas, and suitable reversing-valves and pipes; of a furnace,
containing checkerwork surrounding a working space for reception of the charge,
said checkerwork being divided inside the furnace by imperforate partitions into
separate chambers, with charging and discharging apertures provided with devices
for the exclusion of the external atmosphere; substantially as and for the purposes
described.
8. In apparatus for the reduction of metallic ores the combination of the upright
reducing chamber, having opposite lateral flues or passages at alternate levels, a
reducing gas inlet at one end, and a reducing gas outlet at the other, whereby the gas
in its passage is caused to traverse the ore back and forth in a substantially horizontal
direction, and to pass progressively through the lateral flues or passages; substantially
as and for the purposes described.
9. A furnace for reducing oxides of iron comprising a working space for the

page_text: reception of ore, opposite lateral heat chambers through which the reducing gas may
pass into and from the body of ore respectively, and a gas inlet and outlet ; sub-
stantially as and for the purposes described.
Dated this Seventeenth day of October 1890.
Per pro J. T. KING,
W. B. Johnson.