IMPROVEMENTS IN CALÇINING AND. REDUCING IRON ORES, AND IN FURNACES OR KILNS EMPLOYED IN CONNECTION THEREWITH, WHICH IMPROVE.. MENTS ARE APPLICABLE CHIEFLY TO THE PRODUCTION OF CAST STEEL
Year: 1870

page_text: LETTERS PATENT to Charles William Siemens, of No. 3, Great George
Street, Westminster, in the County of Middlesex, for the Invention
of "IMPROVEMENTS IN CALÇINING AND. REDUCING IRON ORES, AND IN
FURNACES OR KILNS EMPLOYED IN CONNECTION THEREWITH, WHICH IMPROVE..
MENTS ARE APPLICABLE CHIEFLY TO THE PRODUCTION OF CAST STEEL."
Sealed the 17th January 1871, and dated the 30th November 1870.
PROVISIONAL SPECIFICATION left by the said Charles William Siemens
at the Office of the Commissioners of Patents, with his Petition, on
the 30th November 1870.
I, CHARLES WILLIAM SIEMENS, of No. 3, Great George Street, West-
3 minster, in the County of Middlesex, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN CALCIKING AND REDUCING IRON ORES,
AND IN FURNACES OR KILNS EMPLOYED IN CONNECTION THEREWITH, WHICH IMPROVE-
.

page_text: MENTS AKE APPLICABLE CHILFI ΤΟ
follows:-
VE
VASA WARN
In the Specification to my Patent No. 594, dated 28th February 1870,
I described a method of producing cast steel from iron ores by forming
lumps either by the fusion of such ores or by compression of crushed
ores mixed with clay and carbonaceous substances, and by exposing
such lumps to heat in a hot store or double arch furnace in order to
effect the partial or entire reduction of the ore before introducing, the
lumps thus formed and prepared in an open hearth steel melting furnace
described in the said Specification,
'
My present Invention has for its object the production of lumps of
reduced, iron suitable for carrying out the above-named steel making
process, by placing masses of iron ore together with solid fuel into a
closed chamber or "hot store" heated externally, the solid fuel employed
in such chamber being. by préference placed in a separate compartment
or compartments, by which means the carbonic oxide gas generated in
the first instance from the heated fuel is caused to react upon the heated
lumps of ore, taking up oxygen from the same, while the carbonic acid
gas thus formed in returning by a general circulation of the gases to the
heap of solid fuel, takes up another equivalent of carbon, converting it
back into carbonic oxide, which again attacks the ore, and this action
continues until the ore is wholly reduced into metallic iron (excepting its
earthy constituents). The reduction by the above process takes place
very thoroughly and at a quick rate, inasmuch as the circulating carbonic
oxide gas is virtually free from nitrogen, which latter retards the
operation of reduction in ordinary kilns or blast furnaces. The solid
pieces of ore which are to be subjected to this reducing process are by
preference fed into the hot store chamber through a vertical or inclined
shaft or hopper capable of being closed at the top by doors or slides.
The excess of the gases generated in the hot store chamber by the
combination of carbon with the oxygen of the ore rise into this hopper,
where they are burnt by the admission of divided streams of atmospheric
air, the gaseous products resulting from this combustion being allowed
to escape at the top by partially opening the covering slide or door.
The amount of heat developed within the vertical shaft may be further
increased by the admission of combustible gases separately generated, or
by mixing solid fuel with the ore charged in at the top, or by heating
the shaft externally. The ore in gradually descending in the vertical

page_text: hopper or shaft becomes more and more heated, and is thus deprived of
its volatile constituents including water and sulphur, until it reaches
the orifices, through which the atmospheric air enters, whence downward
it passes through a gaseous reducing atmosphere into the heated chamber.
Here carbonaceous substances, such as coal, wood, peat, coke, or
charcoal, are introduced, which may be mixed with the ore, or by
preference placed into divisions of the chamber separated from the ore
as before described, in order to prevent the mixing of ashes with the
latter. The heated ore is drawn forward from time to time from the
vertical or inclined shaft into the reducing chamber, in which it may
also be made to descend on an inclined bed and whence it is removed
at suitable intervals into scoops on wheels or pivots and introduced into
the steel furnace, unless the reduced iron is to be used for other purposes.
Two or more reducing chambers as just described may be provided with
advantage, to be charged with ores of different descriptions. Thus if
three reducing chambers are provided, and the one is charged with
hacmatite, the second with spathic ore, and the third with clay ironstone,
it will be possible to use so much of the reduced ore from the one and
the other that the earthy matters contained in them form a fusible slag in
the steel melting furnace, and render the use of separate fluxing materials
unnecessary. Or the masses of reduced ore may be charged conjointly
with lumps produced by fusion of ores with lime or other fluxing
material as described in the Specification to my Patent, No. 594 of 1870,
or with metallic lumps produced in any other way. In working upon
only one description of ore the solid lumps may be picked out and
reduced by the process, just described, whereas the small ore may be
consolidated and mixed with the necessary fluxing agents by the methods
described in the Specification to my above-mentioned former. Patent.
'