IMPROVEMENTS IN THE PRODUCTION OF IRON AND STEEL
Year: 1872

page_text: PROVISIONAL SPECIFICATION left by Henry Larkin, Andrew Leighton,
and William White at the Office of the Commissioners of Patents,
with their Petition, on the 10th April 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 from time to time made to reduce rich
iron ores at a comparatively low temperature by mixing them with
considerable excess of carbonaceous matter and then calcining in retorts
or other suitable furnaces, but hitherto all such attempts have proved
commercially unsuccessful, mainly owing to the incompleteness and
uncertainty of the results obtained, and the necessity of subsequent
puddling or cementation, for the purpose of burning out the excess of
carbon and contained impurities, and of converting the malleable iron
thus laboriously obtained into steel.

page_text: To obviate the uncertainty hitherto experienced we crush the ore
into powder, generally after roasting. We then take any manageable
quantity of such powdered ore and thoroughly intermingle the whole
quantity so as to obtain an equal mixture throughout. We then calcine
a small portion with an excess of powdered charcoal or other form
of carbon in any suitable apparatus, in order to ascertain by the gas
or gasses evolved what proportion of carbon would be required to
combine with and carry off the whole of the oxygen so removeable,
and thus reduce the contained metal. We also carefully ascertain
the proportion and kind of contained earthy matter and other im-
purities in order to determine the most suitable flux to be employed.
In the case of using any ore existing naturally or artificially in a
finely disintegrated condition such as magnetic iron, sand, or the refuse
from pyrites cinder, we proceed in a similar way to ascertain the exact
proportion of carbon required to combine with the removable oxygen,
and also the flux most suitable for fusing out any contained earthy
matter or impurity.
Having thus obtained accurate data to work from, we thoroughly
mix with the ore the calculated proportion of carbon in the form of
charcoal or anthracite, with any excess that may be desired, together
with the required flux all in a powdered condition. Thus if malleable
iron be required, we simply mix sufficient carbon to combine with and
carry off the removable oxygen, or very slightly more than sufficient
for such purpose. If steel be required we mix one or two per cent.
more carbon, or either more or less than that, according to the quality
of steel intended to be produced. If cast iron be required we increase
the excess of carbon to about five per cent. In all such cases we
accurately regulate the proportion of carbon mixed with the ore, ac-
cording to the proportion desired in the yield of metal to be ultimately
obtained. The mixture so adjusted is then heated in an ordinary gas
retort or other suitable closed chamber to bright redness, and continued
at that heat until carbonic oxide ceases or nearly ceases to be evolved.
By this time the ore will be almost completely reduced to a spongy
metallic condition. If malleable iron or steel be required it may now
be withdrawn and compressed while still at a red heat, then put into a
hotter furnace and raised to a full welding heat and at once conveyed to
the hammer or rollers without any puddling or refining whatever. The
hammer or rollers will squeeze out the intersticial slag as in an ordinary

page_text: bloom, and the required metal will be ready for working. Thus instead
of first obtaining metal of uncertain composition, and afterwards treating
it by various methods in order to bring it as nearly as possible to the
composition required, we by the method described determine the ulti-
mate composition of the metal to be obtained by a proper mixture of
the materials used to obtain it.
To produce cast steel or superior cast iron the proportion of carbon
in the mixture must be correctly adjusted from the data above described,
when the spongy metal obtained may be compressed and then melted
as is usual either in crucibles or in any suitable furnace. Or by a slight
variation of our method the proportion of powdered carbon mixed with
the ore may, if cast steel be wanted, be in excess of that required for
the production of steel, and the heat of the reducing retort kept below
that required to cause the particles of metal to run together. In this
case, when the reduction is sufficiently advanced, which may always be
known by the cessation of carbonic oxide, we convey the reduced metal
in a partially disintegrated or rotten condition into a closed chamber
where it is allowed to cool down. When cold it is crushed into a
fine powder and the whole thoroughly mixed. A portion is then tested
to ascertain the exact proportion of surperfluous carbon, allowing for
the still remaining oxygen. An equivalent proportion of oxide of
iron or of manganese or other suitable oxide is then calculated and
thoroughly mixed in a state of powder with the powdered metal. The
whole is then melted in crucibles or a suitable furnace, during which
operation the oxygen of the oxide unites with the superfluous carbon
and carries it away.