IMPROVEMENTS IN SMELTING IRON AND OTHER ORES
Year: 1873

page_text: LETTERS PATENT to George William Hart, of Upper Norwood, in the
County of Surrey, Engineer, for the Invention of "IMPROVEMENTS
IN SMELTING IRON AND OTHER ORES."
Sealed the 27th March 1874, and dated the 8th November 1873.
PROVISIONAL SPECIFICATION left by the said George William Hart
at the Office of the Commissioners of Patents, with his Petition,
on the 8th November 1873.
I, GEORGE WILLIAM HART, of Upper Norwood, in the County of
Surrey, Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN SMELTING IRON AND OTHER ORES," to be as follows:-
This Invention relates to improvements in smelting iron and other
ores.
In blast furnaces of ordinary construction the ores with fuel and
fluxing materials are introduced at the top, air being blown in at the
base. As regard the gases generated the result is, first, the production
of CO, at the base of the furnace, which gas as it ascends through the

page_text: heated materials above is split up into streams of CO by dissolving
additional carbon. The change of condition which the carbon thus
dissolved undergoes in being transformed from a solid into a gaseous
state, abstracts for every pound of carbon thus vaporized, heat to the
extent of no less then 5,700 units (Fh.) out of a total of 14,500 units,
thereby absorbing uselessly that much of the heating power of the fuel.
The CO thus produced is generally allowed either to pass away into the
atmosphere or is utilized in part for heating the blast or for other
purposes which could be otherwise much more economically effected.
Now the object of my Invention is to obtain from the fuel used
for smelting its full heating power and to utilize such heat to the best
advantage.
In applying my Invention to existing blast furnaces I cover in the
top, and so (or by other means) collect the gases produced in the furnace
and by a fan or other appliance pass the same through a flue or tube
(which descends from the cap or top part of such furnace) into the base
or boshes or other part of the same or of another furnace. Here I
meet these gases which are for the most part CO by a blast of air, by
which means they are burnt and converted into CO,, which gas is
passed into a regenerative furnace charged with red hot or heated char-
coal, coke, coal, or other carbonaceous substance, and is thereby recon-
verted into CO by the absorption of a further amount of carbon. The
CO gas thus produced is applied and used as herein-after named.
"
Sometimes when the furnace is charged in the usual manner (with ores,
carbon, and fluxing material) and the top covered in, I, instead of drawing
off the gases in the manner above mentioned, blow air into the top or
upper part of the furnace, and so cause the gases produced by the com-
bustion of the fuel to pass downwards into the boshes or base of the
furnace, where they are met and burnt by air injected for that purpose
and thereby converted into CO₂, as in the case before described. Or,
instead of blowing air in at the upper part of such furnaces for the
combustion of the fuel therein as just described, I sometimes exhaust
the gases from the bottom or the boshes thereof, by a fan or other
suitable means, creating thereby a partial vacuum. A downward
current is thus created, and air being admitted at the top of the furnace
passes downwards through the fuel, ore, and other material in the
furnace to the bottom or boshes thereof, CO, is thereby produced at the

page_text: upper part of the furnace, which on descending through the carbon
absorbs or dissolves a portion of the same and so reaches the bottom or
boshes of the furnace in the form (for the most part) of CO, where it is
met with air injected or admitted for that purpose, and is thus burnt
5 and converted into CO, which gas is afterwards either reconverted as
before described into CO, or is otherwise disposed of.
The exhaust above described may, when desired, be used in com-
bination with air blown in at the top, as also before set forth.
The economy of the process first above described is that whilst the
heating power of the furnace due to the production of CO is only 4,400
units (and CO is the usual state in which the gases of an ordinary blast
furnace pass into the air) I, by returning these gases and consuming them
as described, either in the furnace in which they have been generated or
in other furnaces, obtain additional heat to the value of 10,100 units per
pound of carbon consumed without further cost of fuel.
The economy of the second process is that sufficient heat is developed
in the top of the furnace for the reduction of the ore to the state of spongy
metal, whilst when the gases produced pass down to the boshes or base
of the furnace there is there produced by the simple admission of air,
and without any additional fuel the heat of 10,100 units per pound of
carbon consumed.
By either of these processes the whole heat of the fuel is rendered
available, whereas in ordinary blast furnaces only about one-third part
is utilized.
Sometimes, as when rich oxides form the ores to be treated, I pass
into a furnace closed at the top CH, gas instead of solid fuel, and such
furnace then needs charging only with ore and fluxing material. The
CH, is in ordinary cases converted into CO and HO (vapour of water),
and as the gas descends the ore is converted into spongy metal, which
when it reaches the boshes or bottom of the furnace is fused by the heat
generated by the combustion of the CO, which is there met by air
admitted for that purpose, and so burnt and converted into CO₂, in which
state this gas may be used for imparting heat to the furnace in which it
has been generated. In this case I construct flues surrounding the
retort in which such ore is contained, and pass the said CO, gas through
such flues prior to conducting it to the regenerative furnace, where it is
treated as before described,

page_text: Sometimes I pass the CO from the regenerative furnace into the blast
furnace charged with the ore and fluxing material instead of CH₂, such
CO when thus introduced being of sufficient heat to effect the reduction of
the ores to spongy metal, which is afterward fused by the CO being met
at the boshes or base of the furnace with fresh air, by which it is con-
sumed and converted into CO₂, which is then treated as before described.
Where however the nature of the ore is such or the conditions otherwise
are such that CO, is the result of passing 00 through the ores, then I
inject, together with air at the boshes or bottom of the furnace, either
CH, gas or fine carbonaceous matter to effect the fusion of the fluxing
materials and the ore. The gases thus produced (which are still for the
most part CO₂) are treated as before described, vizt., either passed through
a regenerative furnace (and so reconverted into CO), and thence to the
top of the same or of another furnace, or passed onwards and otherwise
utilized.
By
The gas CO₂ wherever and however produced is reconverted into CO
by being passed through furnaces charged with some ignited car-
bonaceous substance and heated where practicable by the otherwise
waste heat possessed by the CO2 gas on leaving the blast furnace.
this process the full amount of heat due to the combustion of a pound of
carbon is utilized and the heat abstracted by the vaporization of the solid
carbon in the formation of the CO in the blast furnace is saved, thus
making the total useful heating power of one pound of carbon 20,200
units instead of 14,500.
The regenerative furnaces herein mentioned consist of iron tubes
lined with fire-clay or other fire-resisting material, and are filled with
heated carbon, with which the CO, is brought into contact and thereby
converted into CO, the carbon in the interior being maintained at a
proper heat by the CO2 gas leaving the blast furnace or by any other
means and a small admission of air being provided to maintain the
necessary combustion of the carbon.
In constructing new blast furnaces I prefer to make them of moderate
size and provide two regenerative furnaces to each, so that the CO, on
leaving the blast furnace may be conducted through them alternately;
or this CO, may descend one, pass into the blast furnace as CO, be
therein burnt into CO₂, and then by passing through the second regene-
rative furnace be reconverted into CO, and go thence to the second blast
furnace or be otherwise utilized for refining or for other purposes.

page_text: It is desirable to attach a refining furnace to each one or more blast
furnaces, so that the gases produced in the blast furnaces may be utilized
for the refining in their progress to the regenerative furnaces.
It may be as well to draw attention to the fact that by using the
exhaust and withdrawing the gas from the base of the furnace or by
blowing in air on the top, and so in either case consuming the fuel
downwards, I produce in the first place heat to the amount of
4,400 units (Fah.), which heat is sufficient for the reduction of ores into
spongy metal. In this process CO is formed, and by the further com-
bustion of this CO gas effected at the boshes or base of the furnace by
admitting air there I obtain the remaining heat of 10,100 units (Fah*.),
being the full and entire amount of heat due to the combustion of one
pound of solid carbon. But by the use of my regenerative furnaces I
carry this saving further, as I vaporize therein the second pound of
carbon by the use of the otherwise wast heat of the CO, gas as it
issues from the blast furnace, and so save the additional 5,700 units, which
are required for and absorbed by the vaporization of one pound of solid
fuel. Thus in all the processes after the first I obtain 20,200 units from
each pound of carbon, whereas according to the best authorities the
present blast furnaces utilize only the heat due to the production of 00
or 4,400 units per pound of carbon consumed. Thus in my first process
I save 10,100 units, and in all subsequent operations 14,500 units, or in
other words after getting the heat of 14,500 units from the first pound of
coal I obtain 20,200 from each pound subsequently burnt, which 20,200
units is the rightful heating effect of one pound carbon vapour.
I do not make any special claim to the apparatus herein described for

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day of November, in the
year of our Lord One thousand eight hundred and seventy-three, in the
thirty-seventh year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said George William Hart, Her
special license that I, the said George William Hart, my executors,
administrators, and assigns, or such others as I, the said George
William Hart, 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 Kingdom
of Great Britain and Ireland, the Channel Islands, and Isle of Man,
an Invention for "IMPROVEMENTS IN SMELTING IRON AND OTHER ORES,"
upon the condition (amongst others) that I, the said George William
Hart, my executors or administrators, by an instrument in writing
under my, or their, or one of their hands and seals, should par-
ticularly 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 George William Hart, 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 thereof, that is to say:—
This Invention relates to improvements in smelting iron and other
ores.
In the process of smelting iron and other ores by the ordinary process
and blast furnace where the air is blown in at the bottom of the furnace,
and the gases of combustion are let off or conducted away from the top
the result (as regards the gases generated) is first the production of
carbonic acid gas at the base of the furnace, which gas as it ascends
through the heated contents of the furnace above is split up into streams
of carbonic oxide gas by dissolving additional carbon. The change of
condition which the carbon thus dissolved undergoes on being transformed
from a solid into a gaseous state abstracts, for every pound of carbon
thus vaporized, heat to the extent of no less than 5,700 units (Fahrenheit)
out of a total of 14,500 units (the heating power according to recognized

page_text: authorities of one pound solid carbon), thereby absorbing uselessly that
proportion of the heating power of the fuel. The carbonic oxide thus
produced is generally either allowed to pass away into the atmosphere
or is utilized in part for heating the blast, or for other purposes which
5 could be otherwise much more economically effected.
Now according to my Invention I utilize the whole heating power
of the fuel used in the smelting process besides obtaining amongst other
advantages simplicity in the manufacture and a better quality of metal.
And in order that my Invention may be clearly understood and
readily carried into effect, I will proceed to describe the same with
the aid of the accompanying Drawings, reference being had to the letters
and figures marked thereon.
In applying my Invention to ordinary existing blast furnaces I collect
the gases produced in the furnace by covering in the top thereof or
otherwise, and by a fan or other suitable appliance pass the same
through suitable connections into the base or other part of the same or of
another furnace. Here these gases which consist for the most part of
carbonic oxide are met by a blast of air introduced for that purpose on
which combustion takes place, and the carbonic oxide is burnt and
converted into carbonic acid, which latter gas is treated as herein-after
described.
This form of my Invention is illustrated at Figures 1, 2, and 3, of the
accompanying Drawings in which Figure 1 is a vertical sectional
elevation at the centre line of the blast furnace; Figure 2 a plan, and
Figure 3 a horizontal section taken at the line A, b, Figure 1.
A is the blast furnace covered in at the top by any known and
suitable means; B is the pipe through which the gases of combustion
are drawn away by means of the fan C, whence after being treated as
herein-after described passed on to the holder B for storage (which
holder may be of any well-known and metallic construction), and
are afterward introduced by the pipe B¹ into the base of the furnace
from which they have been drawn, or of another furnace; E are the
tuyers for the introduction of the gas or gases, and F the tuyers for
the introduction of the atmospheric air. The economy of this process is
that whilst the heating power of the furnace due to the production of
carbonic acid is only 4,400 units, (and carbonic oxide is the usual state

page_text: in which the bulk of the gases of combustion of an ordinary blast
furnace pass away, I by consuming this gas as described, either in the
furnace in which it has been generated or in other furnaces, obtain
additional heat of 10,100 units (the heating power of carbonic oxide) per
power of carbon consumed without further cost for fuel.
Sometimes instead of drawing off the gases in the manner above
mentioned I blow air into the top or upper part of the furnace and so
cause the gases of combustion to pass downwards and into the base of
the furnace, where they are met by air injected for that purpose, when
so much of them as remain combustible are burnt, and thereby con-
verted into carbonic acid gas as in the case beforé described. Or instead
of blowing air in at the upper part of the furnace as just described I
sometimes exhaust the gases from the base by a fan or other suitable
means, creating thereby a partial vacuum. A downward current is thus
created, and air being admitted at the top of the furnace the gases of
combustion pass downwards through the fuel ores and other materials in
the furnace to the base thereof, where so much of such gases as remain
combustible are met with air injected for the purpose, and are thereby
burnt and converted into carbonic acid.
This form of my Invention is illustrated at Figures 4, 5, and 6, of the
accompanying Drawings, Figure 4 being a vertical section on the centre
line of the blast furnace, Figure 5 a sectional plan at the line a, b,
Figure 4, and Figure 6 a sectional plan at the line c, d, Figure 4.
A is the blast furnace enclosed at the top as in the previous case;
B is the pipe, through which the atmospheric air is forced or allowed to
pass into the furnace; O is the pipe, through which the gases of com-
bustion are drawn or forced away from the furnace; and D are the
tuyers for the introduction of the atmospheric air.
The economy of this process is as follows:-Sufficient heat is
developed at the top of the furnace for the reduction of the ores to a 3
state of spongy metal, whilst when the gases produced pass down to the
base of the furnace there is there produced by consuming such gases by
the simple admission of air and without any additional cost for fuel the
additional heat of 10,100 units per pound of carbon consumed, the ore
being thus fused.
The two processes above described of producing the downward current,
Tiet
by either blowing air in at the ton of the blast

page_text: be used in combination.
Sometimes the carbonic oxide is introduced at a sufficient high
temperature to reduce the ore to a state of spongy metal, the fusion.
thereof afterwards effected by burning the carbonic oxide in con-
junction with air. This may be effected with apparatus such as that
illustrated at Figures 7 and 8 of the accompanying Drawings, Figure 7
being a vertical central section of a blast furnace, aud Figure 8 a
horizontal section at the line a, b, Figure 7. A is the blast furnace;
O are the tuyers for the introduction of the gas; and B, the tuyers for
the introduction of the air.
When rich oxides from the ores to be treated, and when the fuel used
is hydrocarbon gas instead of solid fuel, I proceed as follows:-I pass
into the furnace closed at the top as before described and charged with
the ore and fluxing material hydrocarbon gas heated or otherwise, and
so cause a downward current. As the gas descends it is (in ordinary
cases) converted into carbonic oxide and vapour of water, the one being
at the same time converted into spongy metal. This, when it reaches
the base of the furnace is fused by the heat generated by the combustion
of the carbonic oxide, which is there met by air admitted or injected for
that purpose, such carbonic oxide being thus burnt and converted into
carbonic acid.
The apparatus illustrated at Figures 4, 5, and 6, and already described
will be found suitable also for this form of my Invention, the hydro-
carbon gas being introduced through the pipe B.
The carbonic acid produced in the process of my Invention is treated
and utilized in the following manner :-Immediately on leaving the
blast furnace, and whilst still retaining its heat, it is passed through
a furnace charged with charcoal, coke, or other carbonaceous substance.
During its passage through this furnace (which I term my regenerative
furnace) the gas both heats or ignites the carbon contained therein and
also certain amount thereof, thus being converted into carbonic oxide,
which may then be again used for fuel in the blast furnace for the
purpose of my Invention either alone or combined with other waste
gases. By this method of heating and so dissolving the carbon by the
otherwise waste heat possessed by the gases of combustion when leaving
the blast furnace the heat abstracted by the vaporization of the carbon

page_text: on the change of the carbonic acid into carbonic oxide (5,700 units) is
utilized on the carbonic oxide being burnt as fuel in the blast furnace
when the full heating power of carbon vapour or 20,200 units per pound
of carbon consumed is obtained, instead of only about 4,400 units as
obtained from the ordinary blast furnace.
If the gases of combustion when passed through my said regenerative
furnace are insufficiently heated to vaporize the carbon contained therein
then the carbon must be heated or ignited by some other suitable means.
For instance it may be ignited and just sufficient air be admitted to
maintain it in an incandescent state, when it will be readily taken up by
the carbonic acid gas when brought into contact with it.
My regenerative furnaces above alluded to may consist simply of tubes
or retorts lined with fire-clay and with suitable inlet and outlet for the
gas. These furnaces are filled with the carbonaceous substances with
which the gases are brought into contact.
When it is desired to specially heat the carbonic oxide before
introducing it to the blast furnace the heating may be conveniently
effected by the use of the well known powers of Siemens' regenerative
stoves, or other known suitable means of heating gases may be
employed.
Figure 9 of the accompanying Drawings illustrates the application to
a Siemens' reverberatory furnace of regenerative furnaces for con-
verting the carbonic acid gas into carbonic oxide, A, A, being my
regenerative furnaces through which the gases of combustion are passed
alternately before leaving or before entering Siemens' furnace.
Whenever in fusing ore according to my Invention by the combustion
of the waste gases with air there is not sufficient carbon in the gases to
effect the fusion and to deoxidise the ore or to prevent its reoxidation by
the flame, then carbon in some convenient convenient form (either solid
or gaseous) is introduced for combustion with the said waste gases.
When constructing new blast furnaces for the purpose of my Invention
I prefer to make them of moderate size, that is to say of not more than
from one-third to one-half the size of the ordinary blast furnace. Each
blast furnace may be combined with two of my regenerative furnaces so
that the waste gases may be conducted through one of them on their g
road to the blast furnace, and so enter the same principally in the form

page_text: of carbonic oxide, and after being therein burnt. into carbonic acid may
on their exit be passed through the other regenerative furnace, and so
be conveyed away as carbonic oxide to be conducted either directly to
another blast furnace or to a gas holder for storage and future use.
'
It is often desirable to combine a refining furnace with each one or
more blast furnaces. This I prefer to place between the blast furnace
and my regenerative furnaces so that the waste gases may be utilized
for refining purposes on their progress to the regenerative furnaces.
To summarise the economy of my Invention I first obtain the heat in
the blast furnace due to the production of carbonic oxide, or 4,400 units
(Fahrenheit), which is about the heat obtained from one pound of carbon
in an ordinary blast furnace, but by the further combustion of this
carbonic oxide at the lower part of the furnace by admitting there air
with the gas according to my Invention, I obtain the remaining heat.
of 10,100 units, which together with the 4,400 previously obtained
makes up the full and entire amount of heat due from the combustion
of one pound of solid carbon or 14,500 units; but by the use of my
regenerative furnaces I effect a still greater economy, as I vaporize
therein the second pound of carbon by the use of the otherwise waste
heat of the gases of combustion as they issue from the blast furnace,
and so save the additional 5,700 units which are required for and
absorbed by the vaporization of one pound of solid carbon. Thus after
the first process
obtain 20,200 units of heat for each pound of carbon
consumed, and I therefore in my first process obtain the advantage over
the ordinary blast furnace of 10,100 units, and in all subsequent
processes 15,800, or in other words after getting the heat of 14,50 units
from the first pound of fuel I obtain 20,200 from each pound subse-
quently consumed, which latter is the full and rightful heating power of
one pound carbon vapour.
In witness whereof, I, the said George William Hart, have
hereunto set my hand and seal, this Eighth day of May, in the
year of our Lord One thousand eight hundred and seventy-