Improvements in the Reduction of Ores.
Year: 1890

page_text: Date of Application, 7th Oct., 1890
Complete Specification Left, 7th July, 1891-Accepted, 5th Dec., 1891
TRUVIDIONAL DI MITICATIOA.
Improvements in the Reduction of Ores.
Communicated from abroad by THOMAS SCHOENBERGER BLAIR, Junior, of
Allegheny, Pennsylvania, United States of America, Metallurgical Engineer.
I JOHN THOMSON KING of 4 Clayton Square Liverpool in the County of
Lancaster Patent Agent do hereby declare the nature of this invention to be as
follows:-
This invention relates to that species of processes for the reduction of oxides of
iron which consists in sending a current of hot reducing gas vertically through a
columnar body thereof.
All of these processes which have ever approximated any successful results
whatever, to wit,-Chenot's, Gurlt's and Tourangin's, belong to a single type of
which Gurlt's may be taken as the most characteristic example. The gas is
introduced at the base of the column of ore and drawn off or left free to escape at
the top. All of them after a more or less limited practical trial have been
abandoned.
The object of the present Specification is to describe my invention whereby the
reduction of oxides of iron by means of a current of hot reducing gases passed
vertically through a columnar mass thereof can be readily and regularly
accomplished.
"
I have discovered that, for success in the prosecution of this operation, three several
and distinct conditions must be provided, as follows:-to wit, there must be, first a
temperature in the gaseous current which shall impart to the ore which it permeates
a red heat which may range between a black red and a yellow but preferably
should be a fairly bright red, second, such a ratio between the impelling force
applied to the gases at the base of the column or the exhausting force at the top
thereof, or both combined, and the resistance of the mass of material that a
thorough reation of the mass shall be secured and third, such due proportion-
between the speed of the chemical action of the reducing gas and the time allowed
for the exposure of the oxides to that action as shall insure the adequate
performance of the desired chemical reaction. Thus where the element of time is
of no special importance the reducing gas may consist of carbonic oxide gas alone,
such as can be generated from coke or charcoal. It can be depended upon to
perform the operation, but with extreme slowness. When it is desirable, and it is
often necessary as regards commercial success, that the reduction should take place
within a less extended time, the result can be reached by adding to the dry
carbonaceous fuel charged into the gas producer, or by using as the sole source of
gas production, bituminous coal, petroleum or the like sources of hydrocarbon
vapors and gases, or by using water-gas; or cyanogen may be developed in the
gas producer by adding to the regular fuel alkaline bodies which will cause the
combination of nitrogen with the carbon of the producer fuel; or cyanides already
formed may be charged with the other material into the producer. I particularize
these special methods of intensifying and accelerating the deoxidizing action of the
gaseous current because they are simple and cheap and readily put in practice, but
do not intend to limit my process to them exclusively.
With the imperfect data now available with reference to the actual. attempts
made to carry out in practice the inventions described in the several Patents of the
parties above mentioned, it is not possible to define with certainty the particular or
particulars, in which, each of them failed to provide that concourse of conditions
essential to success which I have just described. There may, for example, have
been proper temperature and sufficient contact (permeation) yet if there were. not

page_text: proper adjustment of the duration of exposure to the kind of gas used, there would
be failure to secure sufficient deoxidation.
Again there may have been lacking only the single element of adequate
temperature; or again, only that of adequate contact, because of imperfect
permeation.
But whatever may be the value of these conjectures, it is plain that in no case
did the operator provide at one time and in combined action all three of the above
described conditions of success, since I find that whenever they are thus provided
the reduction is accomplished regularly and uniformly and within the limits of
commercial success.
A great variety of devices may be employed for carrying out in practice the
provision, in concurrent action, of the three above described requisites-thermal
mechanical, and chemical.
Deted the 6th day of October 1800
Per pro J. T. KING,
J. Johnson.
COMPLETE SPECIFICATION.
Improvements in the Reduction of Ores.
JOHN THOMSON KING of 4 Clayton Square 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:-
This invention relates to that species of processes for the reduction of oxides of
iron, which consists in sending a current of hot reducing gas vertically through a
columnar body thereof.
All of these processes which have ever approximated any successful results
whatever, to wit-Chenot's, Gurlt's, and Tourangin's belong to a single type of
which Gurlts may be taken as the most characteristic example. The gas is
introduced at the base of the column of ore and drawn off or left free to escape at
the top.
abandoned.
All of them after a more or less limited practical trip have been
The object of the present Specification is to describe my invention whereby the
reduction of oxides of iron by means of a current of hot reducing gases passed
vertically through a columnar mass thereof can be readily and regularly
accomplished.
:
I have discovered that, for success in the prosecution of this operation, three
several and distinct conditions must be provided, as follows:-to wit, there must be,
first a temperature in the gaseous current which shall impart to the ore which it
.permeates a red heat which may range between a black-red and a yellow, but pre-
ferably should be a fairly bright red second such a ratio between the impelling force
applied to the gases at the base of the column or the exhausting force at the top
thereof, or both combined, and the resistance of the mass of material that a thorough
permeation of the mass shall be secured; and third such due proportion between
the speed of the chemical action of the reducing gas and the time allowed for the
exposure of the oxides to that action as shall insure the adequate performance of
the desired chemical reaction. Thus where the element of time is of no special
importance the reducing gas may consist of carbonic oxide gas alone, such as can
be generated from coke or charcoal. It can be depended upon to perform the
operation, but with extreme slowness. When it is desirable and it is often
necessary as regards commercial success that the reduction should take place within
a less extended time, the result can be reached by adding to the dry carbonaceous
fuel charged into the gas producer, or by using as the sole source of gas production,
bituminous coal, petroleum or the like sources of hydrocarbon vapors and gases or
by using water gas; or cyanogen may be developed in the gas producer by adding

page_text: to the regular fuel-alkaline bodies-which will cause the combination of nitrogen
with the carbon of the producer fuel; or cyanides already formed may be charged
with the other material into the producer. I particularize these special methods of
intensifying and accelerating the deoxydizing action of the gaseous current, because
they are simple and cheap and readily put in practice, but do not intend to limit
my process to them exclusively.
In order to illustrate the practical working of my method as above set forth, I
will proceed to describe in detail the operation as conducted with certain definite
materials. Let us suppose that the ore to be treated is a Hematite and therefore of
the composition FeO. It may be either a limonite or a red hematite or a massive
hematite betraying its true nature only by its purple streak or by actual chemical
analysis. It may be either fine or coarse or mixed like sand and pebbles in gravel.
If there is much fine ore and it has any tendency to become pasty when quite wet,
it should not be charged into the reducer until well drained. Mere dampness will
not interfere with the reducing operation, provided the fine ore is loose, that is to
say, not in hard lumps because of being dried when pasty. The lumpy ore should
not exceed two inches average diameter; otherwise extra allowance must be made
for longer time in reaching the core of the lump, according to experience. The
first step in the reducing operation is to heat up the walls of the reducing-chamber.
I do this by turning on the gas at the base of the chamber and igniting it. The
operation will be accelerated if provision be made for introducing a jet of air
through the walls of the reducing-chamber, to impinge on the gas as it enters and
thus secure a livelier combustion than can be had when depending wholly upon the
air that descends from the top of the chamber, baflled as it is by the ascending
current of burning gas. I allow this heating operation to go on for, say, twelve to
twenty-four hours, so that the walls of the reducing-chamber may store up a large
quantity of heat, which will be found serviceable in accelerating the heating up of
the ore which is charged in cold. When the chamber has become properly heated
up, shut off both air and gas and charge in ore enough to fill it to a height of
about two feet and turn on the gas, and in about a quarter of an hour-that is, after
the chill has been taken off the first charge-add another two feet, and after the
lapse of the same length of time as before, another two feet; and so on, if there is
room for more. It will depend altogether upon the condition of the body of
ore as to permeability whether this plan of charging in successive instalments is
called for or not. In commencing the use of a new kind of ore I adopt this
precaution and then continue to use it or not according to experience. It being very
desirable to use the ore just as it comes from the mine. I endeavour to accommodate
my manipulation of it in the reducing-process to suit any peculiarities of its
mechanical condition in respect of ease of permeation by the gaseous current, or the
contrary. For example, should the ore be of such a structure that a considerable
amount of force, either in pressure or suction or both, be required to induce a
sufficiently active flow of gas through it, it may occur that the gas will seek out
channels of lesser resistance, and pass up mainly through them, neglecting more or
less the rest of the body of ore and thus causing inequality in the conversion.
Where such a tendency becomes troublesome Ireverse the movement of the gaseous
current, applying the gas at the top of the reducing chamber, above the mass of
ore, and drawing it off at the bottom. In this case the suction applied to the
outgoing gases should be slight, if used at all. Otherwise the tendency to run in
special channels will be renewed. Having got my reducing chamber properly
charged, adjust the pressure of the ingoing gas according to the indications at its
exit, which tell me the speed at which the current is passing through the body of
ore, and regulate this movement according to circumstances, as follows:-If the
gas, after its escape from the reducing-chamber, is utilized as fuel, there is no
objection to giving it a lively movement through the ore, provided the arrangements
for heating the gas are adequate for imparting to it a medium red heat. The more
rapid the movement, the more rapid the reduction. If the escaping gas is not-

page_text: 4'
utilized, the waste can be partially avoided by giving the current through the ore a
sluggish movement. I utilize the outgoing gas for heating the ingoing current, and
find that, with volume sufficient to supply a current moving at uniform speed every-
where throughout the mass of ore, a. movement which estimate approximately
at equivalent to a stream of water flowing five miles an hour, gives very satisfactory
results. With the temperature and movement above described, a limonite ore, fine
and coarse, as it comes from the mine, will be reduced to practically perfect iron
sponge that is to say, to a condition which renders it a perfectly acceptable
substitute for wrought iron scrap in open hearth practice-in from forty minutes to
one hour. A red hematite ore of open texture will require from ten to fifteen
per cent. longer time, according to degree of compactness, and a true massive
hematite, hard and with a conchoid fracture, should be allowed one hour and a
quarter to one hour and a half. If the ore is magnetite, having the com-
position FeO, the reduction will require under the conditions prescribed above,
from one and a half to two hours. The protoxides of iron, Fe2O, are not amenable
to treatment according to my method. In the foregoing, I have, for the sake of
simplicity, assumed that the chemical constitution of the gas was the proper one for
the purpose. But this requires further explanation. I find that carbonic oxide
alone is altogether too slow in its action on the peroxides of iron to enable me to
prepare the charge of iron sponge in time to be always in readiness for dropping
into the bath of the open-hearth furnace. Since, therefore, this is the most
important of all the applications of my invention, I have discarded simple carbonic
oxide such as is generated from coke or charcoal, and rely upon more active
reducing-agents, as follows:-If hydrogen be added to the carbon, giving us the
hydro-carbon gases and vapors which we obtain from the ordinary gas-producer run
with bituminous coal, or if water gas be used, alone or in mixture with ordinary
producer-gas, the results which I obtain as above described are realized. If lime
or limestone be mixed with the charge in the gas-producer, cyanogen will be
generated in the lower part of the producer where the nitrogen of the inflowing air
passes over incandescent coke with lime in contact with it. Or substances con-
taining or capable of generating cyanogen may be charged into the gas-producer.
The cyanogen in the reducing-gas will be found to increase the rapidity of the
chemical reactions which result in the reduction of the ore. But in practice I find
that ordinary producer gas made from bituminous coal, introduced into the mass of
ore at a medium red heat and caused to permeate it uniformly and with a moderate
speed of movement, and kept in steady action for the length of time called for
according to the mechanical structure and chemical constitution of the ore, all as
above specified, is abundantly competent to give a satisfactory iron sponge within
such limits of time between the charging of the raw ore into the reducing chamber
and the dropping therefrom of the converted material into the bath of the open-
hearth furnace beneath, that the steel-melter always has a charge awaiting the
moment when he has brought his bath into readiness to receive it. At the beginning
of this description of the practical working of my process I spoke of the heating-up
of the reducing chamber prior to charging the ore into it. It is to be understood
that after the first charge has been converted and dumped out, the chamber is in
perfect condition to receive a new charge and, that, in case it is desirable to let
some time elapse before charging again, the chamber can be kept ready for it by
burning a small quantity of gas in the chamber while it is empty.
With the imperfect data now available with reference to the actual attempts
made to carry out in practice the inventions described in the several Patents of the
parties above mentioned, it is not possible to define with certainty the particular or
particulars in which each of them failed to provide that concourse of conditions
essential to success which I have just described. There may for example, have
been proper temperature and suflicient contact (permeation) yet if there were not
proper adjustment of the duration of exposure to the kind of gas used, there would
be failure to secure sufficient deoxidation. Again there may have been lacking

page_text: gas supply pipe enters at 16 and the outlet pipe 17 leads from the upper part of the
kiin. In this outlet pipe I may place a series of exhausting nozzles 20 through
which steam is blown for the purpose of creating draft by vacuum in the pipe and
inducing the gas flow.
In Figure 3, I show a modified form of apparatus, in which the ore to be treated
is contained in a vessel 18, which is set removably in a chamber 19, and is provided
with a perforated bottom. The gas enters the chamber 19 below the bottom of the
vessel 18 passes up through the ore in the vessel and thence escapes through the
outlet pipe.
In using both these forms of apparatus, the gas is caused to traverse the ore by
applying to it pressure and suction, or pressure alone, of the proper degree
proportioned to the resistance of the mass, which will be greater or less, accordingly
as the ore is packed with greater or less density, and according to the depth of the
mass overlying the inlet port.
For the purpose of combining in one apparatus and process, the deoxidation of
the ore and the melting of the resultant spongy iron in the bath of an open hearth
furnace, employ an apparatus as shown in Figure 4, 5, and 6.
In Figure 4. 1, 1', are two of the group of four vertical cylindrical chambers
into which the ore is charged; the removable funnels or gas-discharge stacks 21, 21,
being set aside during the operation; 31, 3' are continuations of the cylindrical
chambers 1, 1, made of increased diameter so that the ore in occupying both,
shall leave an annular space to operate as the means of introducing the gas into the
columnar body of ore. 4', 41, are further continuations downward of the vertical
chambers, for the reception of combustible matter, such as coke, &c., which shall
intercept any free oxygen entering at the joints of the drop bottoms 5', 5. 6' and 7'
are the funnel and conductor which deliver the deoxidized iron sponge through the
opening 8 in the roof 9' of the open hearth furnace 10', directly upon the hearth
thereof (not shown). 11 is the chamber filled with checker-work of brick
enveloping the pipes 12 which convey the reducing gas from its supply pipe 13,
into the reducing chambers. 14, 14', are passages in the walls 15 of the
chamber through which air is admitted and heated before emerging into 111
to ignite and burn fuel gas which is introduced thereinto through pipes 16', and
which by its combustion, heats the reducing-gas in its passage through the pipes 12
and raises it to the temperature required for deoxidation of the ore. 171, 17', are
stacks for carrying off the products of the combustion in 11' and for supplying the
requisite draft therefor.
The method of operation will be readily understood from the Specification at
large and from the special references above to the functions of the several parts.
When it is desired to obtain the iron sponge by a separate and distinct
operation so as to be able to command it for a variety of purposes, an apparatus
may be employed such as is shown in Figures 7, 8, and 9 of the accompanying
drawings.
1, is a cast iron cylinder which constitutes the reducing chamber, into which
the ore is charged, the funnel 211 for the escape of the gas, being removed when it
is to be charged. The bottom of 1 is perforated, as shown to admit the
reducing gas delivered beneath it at 31 after entering through the pipe 12" and
being heated by the checker-work 11, which latter has previously been heated by
the combustion among it, of gas introduced through the pipe 16 and ignited and
burned by the air admitted and heated by the conduit 13"; the products of the
combustion being carried away by the flue 8".
This alternate heating up of the checker-work and subsequent absorption of this
heat by the ingoing reducing-gas, for 1 is accomplished by having a chamber for
the purpose on each side, so that the regenerative action is kept constantly in
operation by the customary manipulation of the gaseous currents. Exterior heat
around is provided by causing a part of the gas entering through 12 to be
deflected into the chamber 4" through the passage 6" before passing into 3".
As

page_text: it enters 4" it is met by a current of air conducted to the spot by and heated in its
passage through the conduit 711; the products of this combustion passing off through
the flue 5".
After the reduction of the ore has been effected, the funnel 2, is removed and
the cylinder is lifted by the lugs out of 4" and placed upon the seat on a box 2011
(Figure 9) the funnel 211 replaced and the joint at the base of the cylinder luted to
prevent the leakage of the non-oxydizing gas which is admitted, cold, into the box
through a pipe 21 at a pressure regulated by the stop cock 22", so as to overcome
the resistance of the contents of 1" and establish through the same a current which
is carried off by the funnel. The temperature of the exterior of 1 and of the gas
emerging from the top of the mass of sponge will indicate when the cooling
operation is completed and the sponge in consequence fitted for exposure to the air
without danger of reoxidation.
It should be understood, as I have already stated that I do not claim the
apparatus herein described, nor do I desire to limit the scope of my invention to its
practice in connection with the said apparatus, since apparatus of various other forms
may be used and I have described those shown in the drawings merely for the purpose
of illustrating some of the many means for putting my invention to practical use.
It is further to be understood that although I have made reference to upward
movements only, the vertical movement of the gas current may, if for any reason
thought desirable, be a downward one. Also, that when describing the mass of ore
as columnar, the qualification is to be understood as not excluding the use of
any other form of the mass that may, owing to special circumstances, be more
convenient.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, declare that what I
claim is :-
First. In the art of reducing metallic oxides by a current of deoxydising gases
passed vertically through a mass of such oxides, the improvement which consists,
first, introducing into such mass a current of reducing-gas heated to the
temperature of the ore when at a red-heat; second, in causing the gas to pass
through the mass by pressure or suction regulated in degree in conformity to the
resistance afforded by the mass of oxides, and third, in continuing the exposure of
the oxide to the heated reducing gas until the combined oxygen is eliminated,
substantially as described.
Second. In the art of reducing metallic ores, the method herein described of
cooling the iron sponge after deoxidation, by passing a current of cold non-oxidizing
gas through the heated deoxidised mass and reducing it thereby to a temperature
sufficiently low to prevent re-absorption of oxygen when subsequently exposed to
the atmosphere; substantially as described.
Third. In the art of reducing metallic ores by a heated reducing-gas, the
improvement which consists in passing through a mass of such ore, a reducing gas
containing cyanogen; substantially as described.
This a L
L. 1801
Per pro J. T. KING.
W. B. Johnson.