IMPROVEMENTS IN THE PRODUCTION OF IRON AND STEEL, AND OF OXIDE OF IRON
Year: 1870

page_text: LETTERS PATENT to Henry Larkin, of Theydon Gernon, in the County
of Essex, Andrew Leighton, of No. 33, Chapel Walks, Liverpool, in
the County of Lancaster, and William White, of No. 30, Thurlow
Road, Hampstead, in the County of Middlesex, for the Invention
of "IMPROVEMENTS IN THE PRODUCTION OF IRON AND STEEL, AND OF OXIDE
OF IRON."
Sealed the 28th February 1871, and dated the 30th November 1870.
PROVISIONAL SPECIFICATION left by the said Henry Larkin,
Andrew Leighton, and William White at the Office of the Com-
missioners of Patents, with their Petition, on the 30th November
1870.
We, HENRY LARKIN, of Theydon Gernon, in the County of Essex,
ANDREW LEIGHTON, of No. 33, Chapel Walks, Liverpool, in the County
of Lancaster, and WILLIAM WHITE, of No. 30, Thurlow Road, Hamp-
stead, in the County of Middlesex, do hereby declare the nature of the
-

page_text: AND OF OXIDE OF IRON," to be as follows:-
The object of our Invention is to obtain iron and steel free from
silicon, sulphur, phosphorus, and other deleterious impurities. For
this purpose we dissolve crude iron or an ore of that metal in an aqueous
solution of hydrochloric acid, first breaking the metal or ore into loose
fragments, or otherwise preparing it so as to present an extensive surface
to the action of the acid. By this operation in the case of the metal
or its prepared sulphite being thus acted on portions of the deleterious
impurities are carried off by the hydrogen gas, which is copiously
evolved, and other portions can readily be separated by subsidence,
crystallization, and other known methods. It is a remarkable fact that
the chief impurities of iron, namely, carbon, silicon, sulphur, phos-
phorus, and arsenic, all form highly characteristic gaseous compounds
with hydrogen, and readily combine with it in a nascent state. The
solution of the crude metal or its ore in hydrochloric acid is carried on
in large covered tanks, from which the evolved impure hydrogen may
be collected and utilized. The resulting solution of ferrous chloride
after having partially settled is then drawn off into another tank, where
it is subjected to further purification. It is then evaporated to partial
dryness and conveyed into a furnace chamber, where it is heated to
redness in contact with a copious stream of aqueous vapour or of aqueous
vapour mixed with oxygen or atmospheric air. By this means the
ferrous chloride is converted into an oxide, while the chlorine passes off
as hydrochloric acid, which may be collected in the usual manner, and
again used for the production of a further charge of ferrous chloride.
Allowing for some small inevitable waste nearly the whole of the hydro-
chloric acid should thus be easily and continually recovered after each
operation, so that the consumption of fuel required for drying and
heating the chloride represents almost the entire loss of material
incident to the production of any given quantity of purified oxide of
iron. If not otherwise utilized we employ the evolved hydrogen for
such heating purposes. In the case of sulphide of iron being operated
on instead of the crude metal the evolved sulphuretted hydrogen would
be utilized for the production of sulphuric acid. Having thus obtained
a. sufficiently pure oxide of iron we reduce it to powder and intimately
mix it with excess of powdered charcoal, anthracite, or coke. We then

page_text: place the mixture in a reverberatory or other suitable furnace, where
at a red heat the oxide becomes quickly reduced to the metallic state
by the action of the carbon. The superfluous carbon is afterwards
burnt out, as in the ordinary "Bessemer process," and the metal run
off in the usual way.
By another arrangement, after purifying the hydrogen evolved during
the production of ferrous chloride, we pass it through a heated chamber
in contact with either the heated chloride or the heated oxide. In this
way very pure metallic iron free from carbon is produced; in the first
case with evolution of hydrochloric acid; in the second with evolution
of aqueous vapour.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Henry Larken, Andrew Leighton and William
White in the Great Seal Patent Office on the 30th May 1871.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, HENRY
LARKIN, of Theydon Gernon, in the County of Essex, ANDREW LEIGHTON,
of No. 33, Chapel Walk, 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 Thirtieth day of November, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-
fourth 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 licence that we, the said Henry Larkin,
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, or 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 King-
dom of Great Britain and Ireland, the Channel Islands, and Isle of
Man, an Invention for "IMPROVEMENTS IN THE PRODUCTION OF IRON AND STEEL,.
AND OF OXIDE OF IRON," upon the condition (amongst others) that we, the

page_text: said Henry Larkin, Andrew Leighton, and William White, our executors
or administrators, 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 :—
The object of our Invention is to produce iron, steel, and oxide of
iron free from deleterious impurities. For this purpose we dissolve
crude iron or any suitable ore of that metal in hydrochloric acid in
order to convert the contained iron into ferrous chloride, which we
then purify by crystallization and afterwards decompose, reconverting
the chlorine of the chloride into hydrochloric acid, which we apply to
dissolve a further portion of iron or ore.
When using the crude metal we either take it in the form of scrap
iron or of spongy iron, or else by granulation, or otherwise so disintegrate
it as to cause it to present an extensive surface to the action of the acid.
During its solution in the acid the sulphur and portions of other dele-
terious impurities are carried off by the hydrogen which is evolved.
The solution is carried on in large covered tanks containing the iron,
and through which the acid is caused to flow. Impure hydrogen is
evolved, in quantity amounting to 15,000 cubic feet per ton of iron
dissolved; this gas is collected and utilized. In the case of using an
ore instead of crude metal we first roast it in the usual manner and
afterward reduce it to powder. We then heat it to redness in any
suitable retort or furnace in contact with coke or other deoxgenating
material in order to reduce any ferric oxide it may contain either into
metallic iron or into ferrous oxide. The black powder obtained is then
stirred in a solution of hydrochloric acid until the contained metal or
ferrous oxide has been dissolved out, becoming converted into ferrous
chloride. By thus avoiding the formation of ferric chloride we not only
minimize the quantity of acid required to dissolve any given weight

page_text: of iron, but we also obtain the iron salt in a form much more easily
crystallizable in a subsequent part of the operation. Four tons of
ordinary commercial acid (specific gravity 1·162) will hold in solution
as ferrous chloride one ton of iron, which solution will require a tank.
of from four to five cubic yards capacity to contain it, whereas, in the
form of ferric chloride one ton of iron would need six tons of acid and
a tank in proportion. The tanks may be made of enamelled iron or of
silicious freestone, as commonly used for the solution of manganese in
the production of chlorine. Where the ore is of such a nature that
without the preliminary operations above described it will yield with
hydrochloric acid a solution in which the iron exists, either for the most
part or entirely, as ferrous chloride, these preliminary operations may
be omitted. The solution of ferrous chloride is allowed to settle, some
scrap iron having been first thrown in to neutralize any excess of acid,
after which the clear liquor is drawn off from the top of the tank by
means of a syphon into an evaporating tank, which may be constructed
of iron, and in which the superfluous water may be rapidly boiled off
by means of heated pipes passing through the liquor. When the boiling
liquor has been sufficiently concentrated, which may be known by its
beginging to crystallize on its surface, it is run off into a third series of
tanks, in which it is allowed to cool. These tanks, containing a saturated
solution, would need to be little more than two cubic yards capacity
per ton of iron, they should be shallow that the liquor may cool rapidly
in them. As the liquor cools it deposits well-formed crystals, which
may be readily removed. The remaining liquor is then again con-
centrated by boiling, and a further crop of crystals again cooled out,
and the operation may be repeated until clear crystals cease to be
deposited. If chemically pure iron or steel be required the crystals
thus obtained may be redissolved in clean water and recrystallized in the
same manner, but for most purposes one crystallization will probably
be sufficient. The crystals are then dried or partially dried either in
shallow pans or on the sunken floor of an oven, or in any other con-
venient way. They are then conveyed to a long and low-roofed oven
or furnace chamber kept at a red heat by means of flues passing under
and over it. This oven is made inclined, so that the material may
readily be raked from the upper to the lower end. At its upper end
is a hopper or feeder for the introduction of the dried chloride, and at
its lower end an opening, by which the chloride residue may be raked

page_text: out after passing through the oven. This opening also serves the
purpose of admitting a quantity of atmospheric air. Near this opening
there is also inserted a series of tubes for the introduction of copious
jets of steam, which steam mingling with the atmospheric air is made
to blow down upon, and then pass up over the heated chloride while
the chloride is stirred, and gradually scraped downwards through the
oven. During this passage through the oven the ferrous chloride, the
oxygen of the atmospheric air and a portion of the aqueous vapour
mutually react upon each other. The iron and the oxygen from the
air and steam combine together and remain as oxide of iron, while the
hydrogen and chlorine become hydrochloric acid gas which passes off
with the nitrogen and excess of steam through a flue provided at the
upper end of the oven. This flue conveys the mingled vapour into
an ordinary condensing tower, where the acid is collected in the usual
way, to be again used in the production of a fresh charge of chloride.
By this arrangement the hydrochloric acid is thus perpetually recovered
after having extracted the iron from its impurities and delivered it up
again in the form of oxide. Having thus obtained a purified oxide of
iron it is readily reduced to the metallic condition as pure iron or pure
steel by well-known methods. For this purpose it may be intimately
mixed with a proper equivalent of powdered charcoal and strongly
heated in a suitable retort or in a reverberatory furnace properly guarded
from contact with oxygen, or it may be heated between two layers of
charcoal in a similar retort or furnace. In either case the heat should
be carried sufficiently high to bring the metal into a spongy or pasty
condition. The metal thus obtained may then be variously treated in
known ways according to the purpose for which it is required.
When iron free from carbon as well as from other impurities is
required we employ an oven similar to that used for the conversion of
the ferrous chloride into oxide, but in this case we blow dry hydrogen
instead of steam upon and over the heated chloride, when hydrochloric
acid is given off and collected as before, while metallic iron in a more
or less powdery condition remains. The metal thus produced requires
to be carefully guarded from contact with oxygen until it has been
agglutinated together by a sufficient increase of temperature. On this
àccount the aperture through which the rake is worked, instead of being
open, as in the former case, will be fitted to the stem of the rake. A

page_text: closed chamber is also provided at the lower end of the oven, into
which the reduced metal may fall and become heated to the requisite
temperature before it is withdrawn.
We claim our improvements in the manufacture of iron and steel, and
of oxide of iron, substantially as described.
In witness whereof, we, the said Henry Larkin and William White,
have hereunto set our hands and seals, this Thirtieth day of
May, in the year of our Lord One thousand eight hundred and
seventy-one.