IMPROVE- MENTS IN THE PREPARATION OF IRON ORES FOR SMELTING, AND IN KILNS
Year: 1869

page_text: LETTERS PATENT to Charles Cochrano, of "The Ellowes," Upper
Gornal, in the County of Stafford, for the Invention of "IMPROVE-
MENTS IN THE PREPARATION OF IRON ORES FOR SMELTING, AND IN KILNS OR
Sealed the 1st January 1870, and dated the 26th July 1869.
PROVISIONAL SPECIFICATION left by the said Charles Cochrane at
the Office of the Commissioners of Patents, with his Petition, on
the 26th July 1869.
I, CHARLES COCHRANE, of "The Ellowes," Upper Gornal, in the
County of Stafford, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE PREPARATION OF IRON ORES FOR SMELTING, AND IN
KILNS OR FURNACES EMPLOYED FOR THAT PURPOSE," to be as follows:
My Invention has reference to the process of deoxydizing iron ores
before introduction into the blast furnace by subjecting, the same to the
action of carbonic oxide gas, and consists of an improved method whereby
instead of acting upon cold iron ore with highly heated carbonic oxide
or blast furnace gas, as described in the Specification to my Patent dated
25 June 1869, No. 1939, or instead of simultaneously heating the ore

page_text: and the carbonic oxide gas, as has also been proposed, the iron ore is in
one and the same furnace or kiln first heated to the requisite degree
and then subjected to the action of carbonic oxide or blast furnace gas
which has not been specially heated for this purpose.
Various arrangements may be employed for carrying this Invention
into practice-Thus in one arrangement I introduce the ore into a
chamber or kiln, at or near the lower end of which cool carbonic oxide
or blast furnace gas is made to enter, which gas after ascending through
the lower strata of the ore is in the upper part of the kiln (constituting
a combustion chamber which may or may not be separated from the
lower part or reducing chamber of the kiln) brought into contact with
jets of atmospheric air, and in entering into combustion therewith is
caused to heat the ore contained in such combustion chamber to the
requisite degree before it descends into the reducing chamber of the
kiln, where it is acted upon by the carbonic oxide gas, and whence it
afterwards issues through shoots at the bottom. By this arrangement
the heat contained in the ore is utilized by being taken up by the gas
on its way to the combustion chamber, the ore passing away from the
kiln in a comparatively cool state, and thus the loss of heat arising in
the before-mentioned processes through the passing away of the ore in a
highly heated condition is prevented. In this arrangement a sufficient
quantity of carbonic oxide or blast furnace gas must be introduced into
the reducing chamber to afford the requisite surplus of unconverted gas
after passing through the ore for producing the necessary heat by com-
bustion with the air in the combustion chamber.
In another arrangement the necessary quantity of combustible gas
is introduced directly and separately into the combustion chamber, and
only such a quantity of carbonic oxide or blast furnace gas is passed
into the reducing chamber as is requisite for deoxydising the ore. The
heat of such gas after passing from the reducing chamber may, if desired,
be utilized by causing the gas to pass in contact with the pipes or flues
conducting the air or combustible gas, or both, into the combustion
chamber, or the hot gas may be allowed to rise up among the ore in
the combustion chamber.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Charles Cochrane in the Great Seal Patent Office
on the 25th January 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
COCHRANE, of "The Ellowes," Upper Gornal, in the County of
Stafford, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent bearing date the Twenty-sixth day of July, in the year of
our Lord One thousand eight hundred and sixty-nine, in the thirty-third
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Charles Cochrane, Her special licence that I, the
said Charles Cochrane, my executors, administrators, and assigns, or such
others as I, the said Charles Cochrane, 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 King-
dom of Great Britain and Ireland, the Channel Islands, and Isle of Man
an Invention for "IMPROVEMENTS IN THE PREPARATION OF IRON ORES FOR
SMELTING, AND IN KILNS OR FURNACES EMPLOYED FOR THAT PURPOSE," upon the
condition (amongst others) that I, the said Charles Cochrane, my
executors 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 immediately
after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Charles Cochrane, 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, reference being had to the Drawings
hereunto annexed, and to the letters and figures marked thereon (that is
to say):-
My Invention has reference to the process of deoxydizing iron ores
before introduction into the blast furnace by subjecting the same to
the action of carbonic oxide gas, and consists of an improved method
whereby instead of acting upon cold iron ore with highly heated carbonic

page_text: oxide or blast furnace gas, as described in the Specification to my Patent
dated 25th June 1869, No. 1939, or, instead of simultaneously heating
the ore and the carbonic oxide gas, as is effected to a certain extent in
the blast furnace and as has also otherwise been done for scientific
experimental purposes only, the iron ore is first heated to the requisite
degree in one part of a special furnace or kiln, and then in another part
of such kiln is subjected to the action of carbonic oxide or blast furnace
gas which has not been specially heated for this purpose.
Various arrangements may be employed for carrying this Invention
into practice-Thus in one arrangement I introduce the ore into a
chamber or kiln at or near the lower end of which cool carbonic oxide
or blast furnace gas is made to enter, which gas after ascending through
the lower strata of the ore is in the upper part of the kiln (constituting
a combustion chamber which may or may not be separated from the
lower part or reducing chamber of the kiln) brought into contact with
jets of atmospheric air, and in entering into combustion therewith is
caused to heat the ore, contained in such combustion chamber to the
requisite degree before it descends into the reducing chamber of the
kiln where it is acted upon by the carbonic oxide gas, and whence it
afterwards issues through shoots at the bottom. By this arrangement
the heat contained in the ore is utilized by being taken up by the gas
on its way to the combustion chamber, the ore passing away from the
kiln in a comparative cool state, and thus the loss of heat arising in the
before-mentioned processes through the passing away of the ore in a
highly heated condition is prevented. In this arrangement a sufficient
quantity of carbonic oxide or blast furnace gas must be introduced into
the reducing chamber to afford the requisite surplus of unconverted gas
after passing through the ore for producing the necessary heat by com-
bustion with the air in the combustion chamber.
In another arrangement the necessary quantity of combustible gas is
introduced directly and separately into the combustion chamber, and
only such a quantity of carbonic oxide or blast furnace gas is passed
into the reducing chamber as is requisite for deoxydizing the ore. The
heat of such gas, if any left after passing from the reducing chamber,
may if desired be utilized by causing the gas to pass in contact with
the pipes or flues conducting the air or combustible gas, or both, into
the combustion chamber, or the hot gas may be allowed to rise up among
the ore in the combustion chamber.

page_text: Having thus set forth the nature of my Invention I will now proceed
more particularly to describe the manner in which it is to be performed,
for which purpose I shall refer to the accompanying Drawings shewing
one of the various arrangements of kilns or furnaces by which my
Invention may be carried into effect.
Figure 1, on Sheet I., shows a vertical section of the kiln. Figure 2,
Sheet II., shews an enlarged sectional plan of the same on line X, X,
Figure 1; and Figures 3, 4, and 5, on Sheet II., shew respectively an
enlarged section on line Y, Y, Figure 4, a section on line Z, Z,
Figure 3, and a sectional plan (still further enlarged) of one of the dis-
charging boxes. Similar letters of reference indicate similar parts in
each of the Figures.
The furnace or kiln consists of a chamber A of fire-brick enclosed in
an iron casing, which chamber is closed at its upper end by a bell valve
B, above which is a closed feeding hopper C for the introduction of the
ore, for the construction of which former Letters Patent have been
granted to me bearing date the 21st February 1868, No. 579. The lower
end of the chamber A is supported by columns I, I, and is contracted to
a funnel shape at A¹, into the centre of which rises the passage for
carbonic oxide or blast furnace gas D, terminating in a conical orifice D',
covered by a conical hood E, so that the gases passing from the passage
D issue into the kiln from under the edge of the hood E. The annular
space formed between the sloping sides A' of the chamber A and the
surface of the conical orifice D' has a number of outlet apertures F
communicating with the iron discharge boxes G fixed by their upper
ends in an air-tight manner to and suspended from the iron casing of
the kiln. Between the outlet apertures F are formed ridges F¹ to
prevent the lodging of ore in the spaces between the apertures.
The construction and mode of operating of the discharge boxes G.will
be more readily understood on reference to the enlarged views thereof
shewn on Sheet II. In order to discharge the reduced ore from the
kiln without at the same time allowing atmospheric air to enter the
kiln through the discharge boxes, each box is provided with three sets of
slides H', H2, H3, of which those H' serve to cut off the communication
between the kiln and the box, while those H cut off the communication
between the upper part and the lower part of the box, and those H³ close
the lower end of the box. By this arrangement if the slides H' are
opened (H2 being closed), a quantity of reduced ore will fall from the kiln

page_text: into the upper part of the box, if now the slides H' are closed and those H*
are opened (H³ being closed) the ore contained in the upper part of the
box will fall into the lower part, and after the slides H* have been closed
those H³ are opened and the ore is discharged into the trucks or on to
the ground. The slides H', H', are opened and closed in opposite
directions respectively by means of the lever K having its fulcrum at K¹
and by means of a pinion L in gear with the rack L' on the slide, the
spindle of the pinion being rotated by a grooved pulley M fixed on the
same, worked by an endless chain N. The slides H are actuated in a
direction at right angles to H' by means of the levers O, O, working on
fulcra O', O', fixed to the columns I. The slides H³ are worked by
pinions P in gear with racks on the slides and rotated by means of
crank handles Q. In order to prevent any escape of carbonic oxide gas
at the slides H, H', these are made. to work backwards and forwards
inside closed casings G¹, G, projecting from the discharge box G; also
in order to prevent as much as possible the entrance of air into the lower
part of the discharge box when the slides H³ are opened for discharging
the reduced ore carbonic oxide gas may be introduced into such lower
space through the aperture G³. Should it be found at any time that the
ore does not descend readily into the discharge boxes from the kiln
stoppered apertures R, R, are provided, through which prising bars
may be introduced and to which access is gained from the gallery S.
At some height above the inlet D' for the carbonic oxide gas side
apertures T, T, are formed round the kiln for the inlet of atmospheric
air in order to effect the combustion of the unconverted portion of the
carbonic oxide gas rising up from below; the air holes are capable of
being closed by stoppers T¹ so as to regulate the inlet of air to the exact
extent required. Access is gained to the air holes from the gallery U.
The action of the kiln takes place as follows:-The kiln being charged
with ore (the lower portion of which may be introduced either in a
heated or cool state) and the valve B and hopper C closed carbonic
oxide gas or blast furnace gas or other suitable reducing gas is introduced
through the passage D into the bottom of the kiln, and in rising up
through the heated lower portion of the ore it acts upon and deoxydizes
the same more or less completely, at the same time taking up the heat
therefrom and becoming itself converted into carbonic acid gas. The
reducing gas is however introduced in such quantity as to be in excess
of the amount required for reducing the ore, so that the unconverted
portion thereof in rising up in a heated state to the level of the air holes

page_text: T enters into combustion with the air passing in, and thereby heats the
ore in the upper part of the kiln to the requisite degree before it is made
to descend into the lower part, in order in its turn to be reduced by the
incoming carbonic oxide gas. The deoxidation of the lower portion of
the ore having thus been effected it is discharged in a comparatively
cool state into the discharging boxes G, as before described, and fresh
ore is introduced into the kiln through the valve B at top. The carbonic
acid and other gases in rising up through the mass of ore above the
air holes T impart their heat to the same, and finally escape through the
side aperture V into a flue in which a draught is produced either by a
chimney or by an exhaust fan, or by both. Should it be found that the
air entering through the apertures T does not penetrate sufficiently
through the mass of ore to effect the equable heating of all parts of the
same this may be facilitated by causing it to pass in through perforated
radial pipes W (shewn in dotted lines, Fig. 1) leading from the
apertures T to a central annular pipe W₁ connecting all the radial pipes
and supported by means of stays W³.
As before stated the arrangement of the furnace or kiln may be
variously modified for carrying my Invention into practice, thus the upper
part or combustion chamber of the kiln may be separated from the lower
part or reducing chamber and be furnished with a separate supply of
combustible gas for raising the ore to the requisite temperature. Or one
or more heating chamber or chambers or retorts may be arranged at the
top of the kiln and the heated ore be discharged thence into the kiln.
Also the reducing gas may be made to enter the kiln through several
side apertures instead of through one single central passage, and the
discharge of the reduced ore may be effected in any other convenient
manner, whereby the inlet of the atmospheric air into the lower part of
the kiln is practically prevented.
Having thus set forth the nature of my Invention, and in what
manner the same is to be performed, I wish it to be understood that I do
not limit myself to the precise means or apparatus for carrying the same
into effect, as herein-before described, with reference to the accompany-
ing Drawings, as these may be variously modified as already stated with-
out departing from the nature of my Invention. Neither do I claim as
part of my Invention the various details of construction of apparatus
herein-before described, except when used in combination for the
purposes of my Invention. Also I am aware that kilns have before

page_text: been constructed with a central inlet for combustible gases covered by a
conical hood, but for totally different purposes, namely, for calcining
minerals and other substances, that is to say, for subjecting the same to
an oxidizing flame, whereas by my Invention the ore is subjected
to the action of reducing gases, and the introduction of oxidizing
gases, as in calcining operations, is carefully avoided; but what I
claim is,―
First. Deoxydizing or reducing iron ores by first raising the ores to
the requisite degree of heat and then subjecting the same to the
action of carbonic oxide or blast furnace gas which has not been
specially heated for that purpose, substantially as herein-before set
forth.
Second. Constructing furnaces or kilns for reducing or deoxydizing
iron ore, wherein such ore is first heated to the requisite degree in one
part of the furnace or kiln, and is then subjected to the action of
reducing gases in another part of the furnace or kiln, substantially as
herein-before described with reference to the accompanying Drawings.
In witness whereof, I, the said Charles Cochrane, have hereunto
set my hand and seal, this Twenty-second day of January, in
the year of our Lord One thousand eight hundred and seventy.
CHARLES COCHRANE. (L.S.)