Improvements in the Manufacture of Iron and Steel.
Year: 1890

page_text: Date of Application, 6th June, 1890
Complete Specification Left, 6th Mar., 1891-Accepted, 30th May, 1891
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Iron and Steel.
I, JOSEPH VON LANGER, Engineer, of 32, Park Row, Leeds, in the County of
York, do hereby declare the nature of my invention to be as follows:-
This invention has for its object to produce iron and steel in reverberatory
furnaces more economically than has been the case hitherto.
It is based on the reducing action of carbonic oxide and hydrogen on metallic
oxides at high temperatures, and on the absorption of carbon by iron at high
temperatures.
These facts are utilized for obtaining iron from its oxygen compounds, by forcing
reducing gases or a mixture of reducing gases with solid carbon or with neutral
gases or a mixture of the latter with solid carbon into molten iron ores.
As this process requires a high temperature, it is preferably carried out in a
Besides the ore-
reverberatory furnace in which the ore bath is highly heated.
bath, the furnace may contain also a bath of pig iron, which immediately absorbs
the metal separated by the reduction. By forcing carbon into the metal bath, the
latter is highly carburetted and thereby prepared for the reduction of a fresh
quantity of iron from the ore.
I prefer to employ a reverberatory gas-furnace with basic or neutral lining, which
furnace may be fixed or moveable.
The material from which the iron is reduced, is, molten iron ore, either alone or
in combination with molten pig iron. The raw materials for the process are iron
ores, slags containing iron and Huxes, or these materials with a certain quantity of
pig-iron, with or without scrap iron and intermediate products.
They may be introduced into the reducing furnace either together or separately,
crude or prepared, and in a solid or liquid condition.
The reducing action may be produced by blowing into the molten ore at a high
temperature carbonic oxide, alone or mixed with nitrogen, or with hydrogen, or
hydro-carbon, or with carbonic acid, or with two or more of these gases.
gas or gas mixture may be added solid carbon.
To the
The reducing gases may be produced from solid carbon, such as coke and charcoal,
or from liquid hydro-carbons. They may be produced in a distant locality or in
the reducing furnace itself, by supplying liquid hydro-carbons to the same.
The reducing gas, either alone or mixed with solid carbon, is blown into the
molten ore and metal, at the required pressure. The gas reduces the iron, and
the excess of carbon carburets the separated iron or the molten pig-iron. After
the blast has been stopped, the carbon in the iron bath acts on further quantities
of iron in the molten ore.
The excess of gases blown into the reducing apparatus may be used for heating
the same.
2000
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.

page_text: COMPLETE SPECIFICATION
Improvements in the Manufacture of Iron and Steel.
I, JOSEPH VON LANGER, Engineer, of 32, Park Row, Leeds, in the County of
York, do hereby declare the nature of my 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 has for its object, to produce iron and steel in reverberatory
furnaces more economically, than has been the case hitherto.
It is based on the reducing action of carbonic oxide and hydrogen on metallic
oxides at high temperatures, and on the absorption of carbon by iron at high
temperatures.
These facts are utilized for obtaining iron from its oxygen compounds, by forcing
reducing gases, or a mixture of reducing gases with solid carbon or with neutral
gases, or a mixture of the latter with solid carbon, into molten iron ores.
This process, which is specially intended for rich ores, should be carried out on
basic or neutral hearths in the presence of strongly basic slag.
The furnaces must be gas furnaces working at a high temperature, and in which
the hot gases are burned with hot air, that is, they should be regenerative or
recuperative furnaces.
The gas serving as fuel may be a good producer gas, or water gas, natural fuel
gas, oil gas or ordinary coal gas.
I prefer, to employ a reversible duplex furnace of Pietzka's system, as described
in the Specification of Patent No. 6399 dated 26 April 1890 and indicated by
Fig. 4 of the accompanying drawings. In this furnace, the two hearths can be
lifted by a hydraulic lift and then turned round at 180°, so as to place hearth I
into the position previously occupied by hearth II, while the latter takes the place
previously occupied by hearth I.
I commence by introducing into hearth I a mixture of ore, charcoal and lime,
the ore and coal, in suitable proportions, having been finely crushed and formed
with a corresponding quantity of calcic hydrate into a thick paste.
This charge is now highly heated, while frequently stirring, and as soon as the
mass begins to melt, hearth II is charged as had been done with hearth I.
When the temperature in hearth I is raised, the charcoal begins to act upon the
ore and precipitates iron from the same.
Now I proceed to completely melt the ore in hearth I, while in hearth II
the same operation is performed as had been done in hearth II.
The fluid mass on hearth I will first consist of highly carburetted iron and of
ore, and after it has been sufficiently heated, the carbon of the highly carburetted
iron will act upon the oxygen of the ore, thereby separating from it a corresponding
quantity of iron and decarbonising the metal bath.
Without the addition of fresh carbon to the bath, the chemical reaction in the
latter would therefore cease after a short time.
To prevent this, I introduce into the metal and ore bath through the door, or
through a specially constructed opening, a nozzle or supply pipe adapted to renew
the supply of carbon, or several nozzles may be introduced through different
openings.
In the accompanying drawings Figs. 1 to 3 represent several devices which may
be employed for this purpose.
Fig. 1 shows a nozzle D made of magnesite or other fireproof material and
communicating with a receptacle a for finely pulverised charcoal. This receptacle
is hermetically closed by a lid i and connected with a pipe 6 for admitting a
non-oxidising gas above the charcoal. The short passage c leading from the
receptacle a to the nozzle D contains a small nozzle d which is connected with

page_text: the supply pipe serving to blow gas into the metallic bath. The sectional areas
are so proportioned, that the nozzle d acts as an injector, drawing solid carbon from
the receptacle a and blowing it into the bath.
The gas supply pipe is preferably situated over the furnace and is connected with
the nozzles d by india-rubber pipes.
The nozzle Ď, together with reservoir a and nozzle d, is mounted on wheels, so
that the whole apparatus may be easily transported from one place to another.
To avoid any oxidising effect of the gas blown into the bath, the said gas should
contain little or no carbonic acid or oxygen; I prefer to employ water gas, which
is a mixture of hydrogen and carbonic oxide, with a small quantity of hydrogen
and carbonic oxide.
Instead of charcoal, I may employ finely powdered retort carbon, coke,
anthracite or coal.
Instead of a blast nozzle, I may employ the apparatus represented by
Figs. 2 and 3. It comprises a receptacle a containing finely powdered charcoal
and connected with the gas supply by a pipe b, but otherwise hermetically closed.
The passage c leading from the receptacle a to the fireproof nozzle or feed
pipe D is constructed as a cylinder and contains a wedge-shaped piston or slide e,
the rod of which extends backward through a stuffing box and is provided with
a handle f. The passage c is also connected with a pipe y, supplying compressed
gas at the required pressure.
The slide e forces the desired quantity of coal-dust into the place designated in
Fig. 3 with the letter and is then withdrawn into the position shown in the same
figure. Subsequently, I admit through the pipe g compressed gas, which blows
the coal-dust through the nozzle D into the metallic bath. Fig. 4 indicates a
nozzle and a feeder mounted on wheels. t represents tap-holes.
The gas blown into the bath contains little or no oxidising gases.
As the temperature of the ore bath is very high, the carbon blown into
the same is immediately burnt by the oxygen of the ore bath, and thereby iron
reduced from the same. In consequence of the great affinity of the iron to the
carbon at high temperatures, the metallic iron separated from the ore will be highly
carburetted and therefore remain a thin fluid.
The carbonic oxide and hydrogen of the gas blast will be oxidised to carbonic
acid and aqueous vapour, and thereby a fresh quantity of iron separated from the
ore bath, which iron is immediately carburetted by the carbon present in the bath.
As the surface of the bath is very large and its depth but small, the gas blown
in at a high pressure and subsequently oxidised will leave the ore bath, before a
decomposition of the carbonic acid and of the aqueous vapour formed in the bath
can take place. Consequently, the ore bath will be reduced by the gas and solid
carbon blown into the same; iron will be precipitated and at the same time
carburetted.
The furnace must be constantly kept at a high temperature, to prevent the bath
from cooling down. Only a determined quantity of gas and coal is thus blown
into the bath for carrying out the process, after which the nozzle is withdrawn and
the bath highly heated.
As soon as the bath is sufficiently hot, the carbon of the highly carburetted metal
begins to act upon the ore not yet reduced, it combines with the oxygen of the
same and precipitates a fresh quantity of iron, simultaneously with the decar-
buration of the metal.
According to the quantity of ore present, its quality, and the temperature of the
metal and ore bath, the operation described may be repeated more or less often
and at corresponding intervals of time; but it will always be necessary, to heat the
bath for some time, after the gas and the carbon have been blown in.
At last the slag resulting from the ore bath will contain but a small quantity of
iron, which requires no further addition of charcoal and gas.
Upon this low oxide (or protoxide) of iron the carbon of the metal bath is allowed

page_text: to act at a high temperature, so as to reduce the iron from the oxide and to decar-
bonise the metal.
For the correct performance of this process, it will always be necessary, to
maintain the slag basic and therefore to add, at suitable intervals, caustic lime,
limestone or any other suitable base..
The metal obtained is now brought to the desired degrees of hardness or
carburation, by suitable additions after known methods, either in the furnace itself
or in a ladle, after which it is drawn off and cast in ingot moulds.
As soon as the metal in the furnace I has been drawn off, the hearths are
reversed in the known manner, so as to place the hearth II next to the gas inlet.
The same work is now performed on hearth II, as has been described with reference
to hearth I, while hearth I is now repaired, and provided with a fresh charge.
As regards the quantities or proportions of the different materials to be employed,
the following conditions should be observed:
If the iron ore is present in, the shape of monoxide, FeO, the reducing process
may be represented by the equation:
Consequently, it is necessary, to blow into the ore bath at least 18 lbs. of carbon for
every 56 lbs. of metallic iron contained in the bath. The 42 lbs. of CO resulting
from the process serve also in this case for heating the hearth.
In practice the quantities of carbon will generally be somewhat larger than those
calculated from the above figures, never smaller.
The quantities of the gases to be blown into the bath must be at least sufficient to
supply the quantities of carbon specified above.
The reducing action of the gases in the gas mixture depends on the temperatures
in the furnace itself and in the various zones of the bath, consequently the
proportions cannot be specified for all cases, but it will always be necessary to
employ an excess of gas, because any excess of reducing gas which escapes from
the ore and metal bath, may be used for heating the furnace and is not, therefore,
¡wasted.
The addition of lime (CaO) to the ore must be sufficient to render the molten
ore, and the slag produced in the course of the process, strongly basic.
The quantity of lime depends on the proportion of silica contained in the ore, and
on the quantity of pig iron (if any) which is used at the beginning of the process.
Every part (by weight) of silicic acid contained in the ore bath, must be
neutralized by at least 2 parts of lime (CaO). In practice, however, the proportion
of SiO, CaO will not be as 1 : 2, but more nearly as 1:3.
:
If pig iron is employed, its weight should not amount to more than 20 per cent.
of the ore bath, and the silica contained in it, must be neutralized by a corre-
sponding quantity of lime.
Instead of the furnace described above, I may employ other kinds of gas
furnaces. The furnace should, however, be a hearth furnace, with a basic
or neutral hearth. The slag, and consequently also the ore bath, must be kept
strongly basic. The process may be modified by partly reducing the ore in any

page_text: other furnace at some distance from the smelting furnace and subsequently
introducing it into the smelting furnace in a fluid or other condition.
The process may also be performed by introducing into the smelting furnace pig
iron, or pig iron and scrap, together with the crude or the prepared ore.
In some cases, pig iron and scrap may be added to the bath in the required
proportions, during the process.
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 1
claim is :-
1. The process for obtaining various grades of carburetted iron (including steel)
from its oxygen compounds, which consists in preparing on the basic or neutral
hearth of a gas-heated open hearth furnace a bath of molten ore and carburetted
iron, with the addition of lime or other suitable base, then blowing into the said
bath a mixture of reducing or neutral gas and finely divided solid carbon, and
subsequently heating the bath, substantially as described.
2. The process for obtaining various grades of carburetted iron (including steel)
from its oxygen compounds, which consists in preparing on the basic or neutral
hearth of a gas-heated hearth-furnace a bath of molten ore and carburetted iron,
with the addition of lime or other suitable base, then blowing into the said bath a
mixture of reducing or neutral gases and finely divided solid carbon, subsequently
heating the bath, repeating the supply of gas and carbon and the subsequent heating,
and adding a fresh quantity of basic slag, when required, substantially as described.
3. In the manufacture of carburetted iron (including steel) from its oxygen com-
pounds, the use of reducing gases blown into the molten ore alone or in mixture
with finely divided solid carbon, substantially as described.
4. The manufacture of carburetted iron from its oxygen compounds in the
manner substantially as described, by means of a reversible duplex furnace heated
by gas.
Dated this 5th day of March 1891
JOSEPH VON LANGER.
By Fairfax & Wetter,
433, Strand, London, Agents.