Improvements in the Process of Reducing Unsmelted Ore, including Roasted Ore, Furnace Cinders, and like material.
Year: 1892

page_text: Date of Application, 9th Sept., 1892-Accepted, 15th Oct., 1892
COMPLETE SPECIFICATION.
Improvements in the Process of Reducing Unsmelted Ore, including
Roasted Ore, Furnace Cinders, and like material.
I, JACOB T. WAINWRIGHT, of 475 Wabash Ave., Chicago, State of Illinois, in
the Republic of the United States of America, do hereby declare the nature of
ny invention for "IMPROVEMENTS IN THE PROCESS OF REDUCING UNSMELTED
ORE, INCLUDING ROASTED ORE, FURNACE CINDERS, AND LIKE MATERIAL," and
in what manner the same is to be performed, to be particulary described and ascer-
tained in and by the following statement:-
My invention relates to an improved method of operating a shaft funace
whereby a more complete separation of impurities from the metal may be effected.
and the quality of the output caused to be more readily controlled by the operator,
and the process is more particulary adapted to the smelting of phosphoric
iron ores.
When smelting iron ores, it has been observed that the most desirable way
consists in subjecting the ore to the action of carbonaceous matter and reducing
gases, and it is important to observe that the temperature should not be excessive,
but should be maintained at a comparatively low degree for the commencement of
These
the reduction, and gradualy increase until the process is completed.
conditions are fulfilled in a simple manner in the usual blast furnace where the ore
gravitates from the coolest part of furnace toward the hottest part.
When smelting iron ores in the usual blast-furnace, it has been observed that
the early stages of reduction occur at the upper part of the shaft, and that from
the sponge iron there produced a cinder liquates which is extremely fusible and
rich in oxide of iron. It has also been observed that this cinder contains in an
unreduced condition nearly all the phosphorus that was in the ore, and that
the proportion of phosphorus that is thus separated from the sponge iron is
dependent upon the quantity of unreduced oxide of iron contained in this cinder.
On account of the comparatively low temperature maintained in the upper part
of the furnace the cinder is not completely fused until it has gravitated with the
charge into the parts below; but during this descent into the hottest part of the
furnace it is acted upon by the reducing gases passing through the shaft, which
effect a partial reduction and thereby reduce not only a portion of the iron there-
from, but also some of the phosphorus.
The phosphorus thus reduced alloys with the iron and contaminates the furnace
product, and the cinder and iron gravitate into the hearth similtaneously.
One object of my present invention is to eliminate the impurities by means of
cinder. Another object in view is to reduce the ore and collect the metal in
such a way that it may not be contaminated by the cinder.
I accomplish this in a shaft furnace wherein reducing gases are caused to take a
downward course through ore which has been charged therein, whereby the cinder
is caused by gravitation to move in the same direction with these gases.
Referring to Figure 2, of the drawing. A shaft furnace is shown having at the
top an opening for admitting the charge, this opening has a movable cover A,
which may be clamped tight when the blast is admitted to the furnace. This
furnace is not operated as a continuous process, but intermittant heats are made,
and the furnace is recharged for each heat. In operating according to my
improvements, when commencing with an empty furnace the contracted portion
of the shaft shown at C, is bridged over with an open mass of solid carbonaceous
fuel such as coke, charcoal, or coal, to the height shown at D. On top of this the
shaft is charged to the height shown at E, with a mixture of ore, flux, and solid
carbonaceous fuel, in suitable proportions. On top of this ore the shaft is

page_text: charged to the height shown at F, with solid carbonaceous fuel, which may be of a
different and cheaper grade than that charged with the ore, and may be mingled
with suitable flux. A blast of air, or other gases that contain free oxygen is then
admitted through the blast pipe B, the top of the fuel ignited, and the cover A,
put in place and clamped tight to prevent leakage of the blast.
The blast pressure is maintained and the process is now in operation. It may
be remarked that the blast may be preheated when the nature of the ore under
treatment makes it desirable, and also that I have not herein attempted to
show the proper kinds and proportions of fuel, and ore; neither have I mentioned
the particular kind of flux to be used; since all may be any of the various
kinds that have been used in metallurgical furnaces, for the treatment of ore, or
for treatment of metal.
Having thus described the method of putting the process in operation, I will
now describe the process.
"
It will be observed that the effect produced by igniting the top of the fuel at F,
and confining the blast in top part of shaft, is to consume this fuel at, or near
the surface and the gases resulting therefrom are forced downward through the
shaft, and out through the gas flue G, whereby these gases may be utilized for
preheating the blast, or for other useful purposes. It will be observed that by
consuming the fuel in this manner the gases resulting therefrom increase in
temperature, and that the final temperature attained is dependent upon the
length of the consumed fuel column. By generating the furnace gases in this
manner the reduction is effected at a gradualy increasing temperature, and thus
the most important requirement of a smelting process is met.
Also this increasing temperature throughout the shaft prevents scaffolding, and
congestion.
The effect produced upon the ore by forcing the gases downward, through same,
is to maintain a reducing action, and also maintain the upper parts of the ore
charge in a hotter, and more reduced condition than those below; consequently
when the reducing action reaches that stage when the cinder separates from the
sponge metal, and gravitates from same, this isolation of the metal will progress
from the top of the ore charge in a downward direction, whereby the cinder collects
in the hearth H, without having been in contact with the sponge metal at a high
temperature. In this way the impurities of the ore remain in the cinder and do not
contaminate the metal.
Since there is considerable difference between the melting temperature of the
cinder, and that of the metal, the cinder may be run out of the hearth by means of
the tap hole I, before the metal melts in the shaft and collects in the hearth.
After the metal collects in the hearth, the blast may be maintained for the
purpose of raising the temperature there, and also for scouring out the shaft.
When recharging for a succeeding heat it may not be necessary to charge fuel into
the bottom of the shaft, but the ore may be charged on top of the unconsumed
fuel of the previous charge.
The action described in this last paragraph relates more particulary to the
smelting of ores when the fluxing material has been proportioned to produce a readily
fusible cinder or slag, and is applicable to the smelting of phosphoric iron ores.
However the fluxing material may be proportioned to produce a slag having a
melting temperature greater than that of the metallic product, in which case the
metal will melt first and may be run out of the furnace before the slag melts,
and is particulary applicable to an efficient smelting of ores containing the more
precious metals. Again the fluxing, material may be proportioned to produce
slag having a melting temperature the same as that of the metallic product, in
which case the metal and slag will gravitate together into the hearth, but the
slag will be in a semifluid and pasty condition and therefore incapable of
contaminating the metal to any great extent, the metal may be run out of the
furnace first, and the slag allowed to remain until a temperature is attained that
will cause it to be sufficiently fluid whereby it may also be run out whereas
a

page_text: in the usual blast furnace there is no provision for raising the temperature in
the hearth whereby the slag may be run out at a higher temperature than that
of the metal.
The furnace hearth is supplied with the usual tap holes at different heights, and
also an opening with a cover to same shown at J.
This opening is convenient for cleaning out and repairing the hearth; also on
account of thus having access to the hearth carbon or other ingredients may be
charged into the molten bath for the purpose of making a definate alloy, or the
metal may there be refined by charging it with ore, lime, florspar, or other
ingredients that are used for this purpose in the various open hearth processes;
or if desirable the metal may be conveyed from this furnace and treated by the
pneumatic, open-hearth, or any of the known refining processes.
Figure 1, shows another device for operating my invention, and is particulary
adapted for utilizing cheap solid fuel, whereby this cheap fuel is isolated from
the remainder of the furnace charge for the purpose of preventing contamination
with the metal, and also to keep out of the smelting furnace the ash resulting
from this fuel.
A shaft furnace L, like that shown in Figure 2, is connected by means of the
flue M, to the similar shaft furnace N, wherein this cheap fuel is charged
separately for each heat, ignited at the bottom, and blasted by means of the
blast pipe O. The shaft L, is charged and operated in a manner like that
described for Figure 2, with the exception that instead of charging the fuel on
top of the ore charge, this fuel is charged into the shaft N, and the covers P,
and S, are replaced and fastened so as to confine the gases. The ash resulting
from the consumption of the fuel in the shaft N, collects in the bottom of the
shaft, and is periodicaly removed through the opening at R, which is kept closed
when the blast is turned on.
Since by this invention any desired temperature may be finaly attained in the
hearth, it may be remarked that steam, water gas, or other gases containing
hydrogen may be mixed with the furnace gases during the carly stages of the
process, or at any desirable time, and thereby utilized as a refining agent for
effecting a more thorough elimination of sulphur and other impurities from the
metallic product, and may be effected by any usual method of introducing steam
into a furnace blast.
The inside lining of my furnace may be in part or in whole of such acid, neutral,
or basic material as has heretofore been used in constructing metallurgic furnaces;
but it may be remarked that furnace linings are greatly improved by being made
thin and properly cooled.
The scope of my invention is not limited to the use of solid fuel, for the furnace
gases may be generated from other sources, and adapted to meet the requirements
as hereinafter set forth in Claim No. 1.
I am aware that there is nothing new in the use of a shaft furnace having a
downward draft, I am also aware that it is not new to place fuel in a furnace
through which an upward blast is passed for the purpose of generating a gaseous
product which is to be used in the reduction of ore in an adjacent furnace.
My invention in its broadest scope consists in generating gases at successionally
increasing temperatures, and passing these gases downward through unreplenished
ore. Thereby I effect an increasing temperature throughout the ore, and reduce
this ore progressively from the top towards the bottom; whereas heretofore gases
thus generated have not been used for smelting purposes by passing same down-
ward through ore which is not kept replenished; and it may be remarked that
gases may be thus generated by any of the well known devices that have been
used for this purpose such as hot-blast stoves, and gas producers in which the
generated gases result from combustion of unreplenished fuel; and again, gas
producers in which fresh fuel is continuously charged, or caused to gravitate into
the draft of the gases to replace the consumed fuel, generate gases successively
at a uniform temperature, the fuel and blast remaining the same.

page_text: Claim 1, hereinafter set forth is intended to cover my invention in its broadest
scope.
The examples shown by the drawing aud herein before described are different
ways of applying the invention that is set forth in this claim.
"
It is herein understood that the meaning of the word “unreplenished is intended
to include partial replenishment as an equivalent.
It is herein understood that a shaft furnace is one in which a blast is caused to pass
through a shaft and permeate the furnace charge confined therein. This includes
the well known type of furnace wherein the charge is confined in a shaft which
is provided with side flues for conveying the furnace gases across this shaft and
through the charge, these furnaces are usualy built as an upright shaft having
a system of side flues for causing the furnace gases to cross and recross this
shaft at successive heights; and the treatment of ore in a furnace of this
description, wherein the furnace blast is passed through the ore at a certain
elevation, and caused to repass through the same ore charge at a lower elevation,
is herein understood to be an equivalent of passing gases downward through
this ore.
It is also understood that any operation herein mentioned in connection with
my invention may be performed in any manner that is suitable, and known in
the present state of the various arts to which the operation under consideration
has been applied.
In Claim 1, hereinafter set forth, I have described only the essential operations
that make up my invention, and I have therein described these operations in as
broad and general manner as the present state of the art will permit; and it
will be observed that where I have mentioned the application of an operation
without describing same in detail, and which might seem somewhat vague, this
Specification contains descriptions of two or more different ways of effecting this
particular operation as applied to my invention, consequently in the claims I am
obliged to describe such operations in a broad and general way, in order to cover
my invention in its broadest sense, and confine the claims to one genus and one of
each successive subdivisions under this genus.
Having now particulary 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―
Claim 1. In the art of reducing unsmelted or partly smelted ore, the improved
method of operation which consists in generating gases at successionally increasing
temperatures, passing these gases downward through ore, and maintaining this ore
in an unreplenished condition, substantially as set forth.
Dated this 9th day of August 1892.
JACOB T. WAINWRIGHT.