IMPROVEMENTS IN THE PRODUCTION OF Iron and Steel
Year: 1872

page_text: LETTERS PATENT to Henry Larkin, of Theydon Gernon, in the
County of Essex, Andrew Leighton, of No. 16, South Castle Street,
Liverpool, in the County of Lancaster, and William White, of No. 30,
Thurlow Road, Hampstead, in the County of Middlesex, for the In-
66
vention of IMPROVEMENTS IN THE PRODUCTION OF Iron and Steel.”
Sealed the 26th November 1872, and dated the 8th October 1872.
PROVISIONAL SPECIFICATION left by the said Henry Larkin, Andrew
Leighton, and William White at the Office of the Commissioners
of Patents, with their Petition, on the 8th October 1872.
We, HENRY LARKIN, of Theydon Gernon, in the County of Essex,
ANDREW LEIGHTON, of No. 16, South Castle Street, Liverpool, in the
County of Lancaster, and WILLIAM WHITE, of No. 30, Thurlow Road,
Hampstead, in the County of Middlesex, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN THE PRODUCTION OF IRON AND
STEEL," to be as follows:-
Many attempts have been made to reduce rich iron ores at a compara-
tively low temperature by mixing them with considerable excess of
carbonaceous matter, and then calcining in retorts or furnaces; but

page_text: hitherto all such attempts have proved commercially unsuccessful,
mainly owing to the incompleteness and uncertainty of the results, or
to the necessity for subsequent puddling and cementation for burning
out the excess of carbon and other superfluitics, and of converting the
malleable iron thus laboriously obtained into steel.
In carrying out our Invention herein-after described, we use ore in a
finely divided or granular condition, such as magnetic iron sand, certain
forms of micaccous iron ore, and the purified refuse from pyrites cinder;
or we take any suitable rich ore as ordinarily found, and crush it into
powder. We then thoroughly mix and carefully sample out a small
portion of the given powdered or granular ore, and ascertain, by passing
bydrogen over it at a red heat and noting the loss of weight, the per
centage of removable oxygen it contains, after which the per centage
of carbon is calculated which would be required to unite with such
ascertained oxygen in the formation of carbonic oxide. Any con-
venient quantity of the said ore is then taken and thoroughly
mixed with as nearly as may be such an equivalent of carbon, or with
more or less carbon, according to the product required. The carbon
thus added may be in any convenient form, such as coal dust, wood
sawdust, disintegrated peat, or preferably in the form of powdered
charcoal, or anthracite. The mixture so adjusted of carbon and ore is
then heated to bright redness in an iron or other suitable retort or
partially closed chamber, and continued at that heat so long as carbonic
oxide is evolved. By the time the evolution of gas ceases the ore will
be more or less completely reduced to a metallic condition, but still
retaining its powdered or granular form, care being taken that the heat
during the reduction shall never be so high as to cause the metallic
particles to cohere together.
When an iron retort is used it should be surrounded in the fire by a
refractory jacket to prevent it from burning, or it should be heated by a
deoxidised current of hot air. When the operation is completed the
retort is removed, and with its contents is allowed to cool down without
access of atmospheric air, and a fresh retort similarly charged is put in
its place.
When the powdered or granular metal thus obtained is sufficiently
cooled it is removed from the retort, and thoroughly intermingled so as
to obtain a correct average mixture throughout, or if more convenient
the contents of several retorts may be thus intimately and thoroughly

page_text: mingled together. A small portion of this metallic product is then, as
with the original ore, carefully sampled and tested to ascertain the per
centage if any of oxygen and of carbon remaining in it.
We estimate the per centage of carbon by calcining in a combustion
tube an accurate sample of the material with bichromate of lead and
chlorate of potash, and weighing the carbonic acid evolved. If the pro-
portions of oxygen and carbon should be found to be not such as required
the needful per centage of ore or of carbon (which this time will be very
small) may be added in the form of powder, and thoroughly mingled as
before. The material is then replaced in the retort, and again heated as
already described until carbonic oxide ceases to be evolved. If the pro-
portions of ore and carbon are adjusted with reasonable care this second
adjustment should ensure a very accurate result, but it is evident that by
repeating the process almost any degree of accuracy may be obtained.
Or, in place of working in the manner above described, we may proceed
according to the process set forth in the Specification of our former
Patent, dated the 8th day of June 1871, No. 1518, and obtain a residue
of iron and carbon by calcining ferrous chloride with moist peat or with
wood sawdust. This residue we then operate on in a similar manner,
that is to say, we test the mixture to ascertain the per-centage of carbon
contained in it, and then add oxide of iron.
Having thus from whatever material obtained the metal in a powdered
or granular condition, and accurately tested it, we next intimately mix
therewith (also in a state of powder) any suitable flux to combine with
the silica and other impurities contained in it. For this purpose, and in
this way, we especially use either red or black oxide of manganese or
any other suitable compound containing manganese, or we use fluorspar,
clay, or lime, or any or all of them, according to the character of the ore
operated on.
To obtain cast steel we take the mixed material so prepared, having
carefully adjusted the proportion of carbon according to the quality of
steel required, and melt it down into steel and slag either in crucibles or
in any suitable furnace, after which the molten steel is run into moulds
in the usual way.
In order to protect the crucibles or the melting furnace from the
action of the flux, and to protect the contained steel from the carbon in
the crucibles in case of plumbago being used, we line them or either of

page_text: them with any suitable refractory material, such as a mixture of clay and
burnt clay or alumina, if the ore be silicious, or any highly silicious
material, such as ganister, if the ore should be aluminous. By this
arrangement we are enabled to use a much thinner and more effectual
flux than would otherwise be practicable.
A very superior cast iron may also be obtained in a similar manner
by increasing the proportion of carbon in the given material.
If soft malleable iron or steely iron be required, it will not be necessary
to raise the heat to the point of fusion, a full welding heat, as in
an ordinary bloom from a puddling furnace, being sufficient. In this
state the metal is at once conveyed from the furnace or crucible to the
hammer or squeezer, where it is compressed in the usual way, and the
intersticial slag squeezed out.
When soft or when steely iron is required there must be a propor-
tionate decrease in the calculated quantity of carbon; and in almost all
cases, whether in the production of iron or steel, we find it desirable that
the material should contain a small per-centage of oxide of iron or other
suitable oxide to oxidise the small portion of silicon, which seems
generally to be reduced with the powdered metal, and thus enable it to
pass into the slag.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Larkin, Andrew Leighton, and William
White in the Great Seal Patent Office on the 8th April 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, HENRY
LARKIN, of Theydon Gernon, in the County of Essex, ANDREW
LEIGHTON, of No. 16, South Castle Street, Liverpool, in the County of
Lancaster, and WILLIAM WHITE, of No. 30, Thurlow Road, Hampstead,
in the County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Eighth day of October, in the year of
our Lord One thousand eight hundred and seventy-two, in the thirty-
sixth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said Henry Larkin, Andrew Leighton, and
William White, Her special license that we, the said Henry Larkin,

page_text: Andrew Leighton, and William White, our executors, administrators,
and assigns, or such others as we, the said Henry Larkin, Andrew
Leighton, and William White, our executors, administrators, and
assigns, should at any time agree with, and no others, from time to time
65 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 THE PRODUCTION OF IRON AND
STEEL," upon the condition (amongst others) that we, the said Henry
Larkin, Andrew Leighton, and William White, our executors or adminis-
trators, by an instrument in writing under our or their hands and seals,
or under the hand and seal of one of us or them, 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 we, the said Henry Larkin and William
White, on behalf of ourselves and the said Andrew Leighton, 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 has for its object improvements in the production
of iron and steel.
In carrying out our Invention we use ore in a finely divided or
granular condition, such as magnetic iron sand, micacious iron ore,
and the purified refuse from pyrites cinder known as purple ore, or
we take any suitable rich ore, as ordinarily found, and crush it into
powder. We then thoroughly mix and carefully sample out a small
portion of the given powdered or granular ore, and ascertain by passing
hydrogen over it at a red heat and noting the loss of weight, the
per centage of removable oxygen it contains, after which, the per centage
of carbon is calculated which would be required to unite with such
oxygen in the formation of carbonic oxide. Any convenient quantity
of the powdered ore is then taken and thoroughly mixed with such
equivalent of powdered carbon, or with more carbon, according to
the product required. The carbon thus added may be in any convenient
form, such as coal or coke dust, wood sawdust, disintegrated peat,

page_text: or preferably in the form of powdered charcoal or anthracite. The
mixture so adjusted of carbon and ore is then heated to bright redness
in an iron retort with a movable cover, a sufficient aperture being
allowed for the escape of the carbonic oxide formed. By the time the
evolution of gas ceases, or nearly ceases, the ore will be more or less
completely reduced to a metallic condition, but care should be taken
that the heat during the reduction shall never be so high as to cause
the metallic particles to cohere together into a fused mass.
In order to prevent the separation of the oro and carbonaceous
matter during the evolution of the gas, we resort to the method
described in our Provisional Specification, dated the 8th of April, 1873,
(that is to say) we weight the surface of the material in the retort,
either with heavy iron ore, or with granulated iron; these materials
are easily separated from the other contents of the retort when the
process is complete; a depth of three or four inches of the weighty
material will be found sufficient. The iron retort should be surrounded
in the fire by a refractory jacket. When the powdered orc is
sufficiently reduced the retort is removed and its contents allowed
to cool down without access of atmospheric air, and a fresh retort,
charged as described, is put in its place. When the retort with its
contents is sufficiently cooled, the material thus obtained is emptied
out and thoroughly disintegrated and intermingled so as to obtain a
uniform average throughout, or the contents of several retorts may
be thus intimately and thoroughly mingled together. A small portion
of this metallic product is then carefully sampled and tested to ascertain
the per-centage (if any) of oxygen and of carbon remaining in it.
We estimate the per centage of carbon by calcining in a combustion
tube the given sample with chromate of lead and chlorate of potash, and
weighing the carbonic acid evolved. If the proportions of oxygen and
carbon are found to be not such as required, the needful per centage of
ore or of carbon (which this time should be very small) may boʻadded in
the form of powder, and thoroughly mingled as before. The material is
then replaced in the retort, and again heated as already described,
although the time required in this second instance will be much shorter.
If the proportions of orc and carbon are adjusted with reasonable care;
this second adjustment should ensure a very accurate and reliable result.
Or, in place of working in the manner above described, we may proceed
according to the process set forth in tho Specification of our former

page_text: Patent, dated the 8th day of June 1871, No. 1518, and obtain a residue
of iron and carbon by calcining ferrous chloride with moist peat or with
wood sawdust. This residue we then operate on in a similar manner.
Having thus from whatever material obtained the metallic product in
a powdered or granular condition, and accurately mingled (and having.
if necessary again tested it), we next intimately mix therewith (also in a
state of powder) any suitable flux or fluxes to combine with and fuse out
the various earthy and other impurities contained in it, but always
making due allowance for any removable oxygen which may be con-
tained in such flux or fluxes. For this purpose and in this way
we especially use any suitable oxide or other compound containing
manganese, and we use fluorspar, clay, and lime, or any of them,
according to the character of the earthy impurities in the ore originally
operated on, and we adjust the proportions of these fluxes in such
manner as to obtain a fusible slag of such a nature as not seriously to
injure the pots or containing vessels, as is well understood and practised
in other metallurgical operations. It is also easy in a similar way to
increase the proportion of carbon at this part of the operation, should
such increase be desirable.
To obtain cast steel we take the mixed material so prepared, having
carefully, as described, adjusted the proportion of carbon according to the
quality of steel required, and melt it down either in crucibles or in any
suitable furnace, after which the molten steel is run into moulds in the
usual way.
In order to protect the crucibles from the action of the flux and to
protect the contained steel from the carbon in the crucibles in case of
plumbago being used, we line them with any suitable refractory silicious
or aluminous material free from carbon, such as ganister or bauxite.
A superior cast iron may also be obtained in like manner and at a
much lower melting heat by increasing the proportion of carbon in the
given material.
If soft malleable iron or steely iron be required there must be a pro-
portionate decrease in the quantity of carbon. In this case it will not be
necessary to raise the heat to the point of fusion, a full welding heat as
for an ordinary bloom of a puddling furnace being sufficient. In this
state the metal is at once conveyed from the furnace to the hammer or

page_text: squeezer, where it is compressed in the usual way and welded into a
coherent mass, and the intersticial slag squeezed out.
Having thus described the nature of our said Invention and the
manner of performing the same, we would have it understood that we
claim,-
First. The production of iron and steel substantially in the manner
described.
Second. The process in the manufacture of iron or steel of reducing
iron ore by heating it with carbonaceous matter, and then (after
analyzing the product) adjusting the proportions of carbon and oxygen 1
and reheating the mixture, substantially as described.
Third. The process in the manufacture of steel of producing an
adjusted and intimate mixture of reduced iron ore and carbonaceous
matter in a finely divided state, then adding powdered flux to such
mixture and melting it, substantially as described.
Fourth. The process in the manufacture of iron or steel of mixing
reduced iron ore in a finely divided state (with or without carbonaceous
matter) with powdered flux, and beating such mixture and welding,
substantially as described.
In witness whereof, we, the said Henry Larkin and William White,
have hereunto set our hands and seals, this Seventh day of April,
in the year of our Lord One thousand eight hundred and seventy-
three.
{
HENRY LARKIN.
(L.B.)
WILLIAM WHITE. (L.S.)