IMPROVEMENTS IN THE CONSTRUCTION OF FURNACES FOR CALCINING ORES OTHER SUBSTANCES, AND IN THE METHOD OF WORKING THE SAME
Year: 1869

page_text: LETTERS PATENT to Thomas Gibb and Charles Gelstharp, both of
Jarrow-on-Tyne, in the County of Durham, for the Invention of
"IMPROVEMENTS IN THE CONSTRUCTION OF FURNACES FOR CALCINING ORES
PROVISIONAL SPECIFICATION left by the said Thomas Gibb and
Charles Gelstharp at the Office of the Commissioners of Patents,
with their Petition, on the 22nd October 1869.
We, THOMAS GIBB and CHARLES GELSTHARP, both of Jarrow-on-
Tyne, in the County of Durham, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF FURNACES FOR
CALCINING ORES AND OTHER SUBSTANCES, AND IN THE METHOD OF WORKING THE
SAME," to be as follows:-
Instead of the working bed ordinarily employed in reverberatory
furnaces a horizontal pan which is caused to revolve on its vertical axis
is used. On this pan the ore or other material to be calcined is spread
as on the ordinary furnace bed, and the stirring thereof, which is usually
performed by rakes worked by manual labour, or in some cases mecha-
nically, is effected by a plough-shaped stirrer, which turns the ore or
other material over as it is carried forward by the revolution of the pan

page_text: The stirrer is moved gradually across the pan and it is preferred that
this movement of the stirrer as well as the revolution of the pan be
effected by means of suitable machinery, such as is well known and under-
stood. More stirrers than one may be used, and the stirring may be
effected without lateral motion.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Thomas Gibb and Charles Gelstharp in the Great
Seal Patent Office on the 22nd April 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, THOMAS
GIBB and CHARLES GELSTHARP, both of Jarrow-on-Tyne, in the County
of Durham, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of October, in the year of
our Lord One thousand eight hundred and sixty-nine, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said Thomas Gibb and Charles Gelstharp,
Her special licence that we, the said Thomas Gibb and Charles Gels-
tharp, our executors, administrators, and assigns, or such ethers as we,
the said Thomas Gibb and Charles Gelstharp, our executors, adminis-
trators, and 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 Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN THE CON-
STRUCTION OF FURNACES FOR CALCINING ORES AND OTHER SUBSTANCES, AND IN THE
METHOD OF WORKING THE SAME," upon the condition (amongst others) that
we, the said Thomas Gibb and Charles Gelstharp, our executors or
administrators, by an instrument in writing under our, or their, or
one of their hands and seals, should particularly describe and ascer-
tain 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 Thomas Gibb and Charles
Gelstharp, do hereby declare the nature of our said Invention, and

page_text: in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement, reference being
had to the Drawings hereunto annexed, and to the figures and letters
marked thereon, that is to say :-
Instead of the working bed ordinarily employed in reverberatory
furnaces we replace the same by and use in lieu thereof a horizontal
pan which is caused to revolve on its vertical axis. On this pan the
ore or other material to be calcined is spread as on the ordinary furnace
bed by a series of scrapers lowered through the roof of the furnace.
The stirring of the ore or other substance, which is usually performed
by means of rakes worked by manual labour, or in some cases by the
assistance of mechanical appliances, we effect by a plough-shaped stirrer,
which turns the ore or other substance over as it is carried forward by
the revolution of the furnace bed or pan. The stirrer is moved slowly
and gradually in a direction radial to the circle of the bed, so that every
portion of the ore is turned over from time to time. When the ore is
sufficiently calcined we discharge it by the same scrapers that are used
to spread the charge, and which are arranged to throw the ore or other
substance outwards, and are lowered into contact with the revolving
bottom of the bed or pan, and kept in that position until the whole
of the ore or other substance has been discharged over the side of the
pan.
The nature of our said Invention, and the mode of carrying the same
into execution, will be more clearly understood by reference to the
annexed Drawings, which shew a reverberatory furnace with the before-
mentioned arrangements.
Figure 1 represents a horizontal section at the level of the fire
bridge; Figure 2 is a vertical section on the line A, B, on the horizontal
section as represented in Figure 1; Figure 8 is a vertical section on
the line C, D; and Figure 4 is an elevation of the furnace.
The furnace bed is formed of the revolving pan a, which is made of
iron and lined with fire-brick and carried on wheels and a central
bearing in the same manner as a railway turntable. The scrapers above
mentioned are represented at b, and consist of a series of iron plates
suspended so as to pass through the roof of the furnace when required.
These plates are set in such a manner as to cross a radial line of the
pan obliquely, so that their edges which are nearer the centre face the
direction in which the pan advances. The ore or other substance which

page_text: is carried against the plates is thrown towards the circumference, and the
latter are set at such distances that the ore thrown outwards by one
plate is taken up by the one next from the centre, and no part of the
area of the pan is missed. In charging the furnace the plates are
lowered to such a height above the revolving bed as is intended for the
upper surface of the charge of ore, and on ore being run into the furnace
through a shoot the revolution of the bed carries any portion which is
above the proper level against the plates, by which it is uniformly spread.
The plates are then raised out of the furnace and the calcination goes
on, the ore or other material being continually turned over by the
plough-shaped stirrer c, which is kept in contact with the bed by the
arm d, and set to face the direction in which the ore is carried against
it by the revolution of the bed. The arm d is moved by a lever at its
outer end in a direction radial to the circle of the furnace bed, and its
motion is so much slower than that at which the bed revolves that in
one revolution of the latter the stirrer shall not move more than its own
breadth, so that in once travelling between the centre and the cir-
cumference of the bed the stirrer will have been in contact with every part
of its area. When the ore is sufficiently calcined the plates 6 are
lowered into contact with the bed, and the hinged plate e turned back
so that its inner edge is in contact with the outermost of the series of
parallel plates. The plate e when so placed rests on the edge of the
pan. The ore carried against the parallel plates is thrown towards the
circumference by each into the path of the neat plate, by which it is
again thrown outwards in the next revolution, and at last against the
plate e, by which it is discharged over the pan on to a shoot, from which
it may be received into waggons.
Instead of the traversing plough-shaped stirrer above described the
ore or other substance may be turned over by another series of parallel
plates set like the series of discharging plates above mentioned, but
with the edge nearest the circumference facing the direction in which
the pan advances. This set of plates will throw the ore towards the
centre of the pan, and when lowered with the series of plates above
described every portion of the ore or other material will be thrown
towards the centre by one set, and towards the circumference by the
other, and so turned over at each revolution of the pan.
In using
this method of stirring the plates will require to be lowered only at
intervals.

page_text: In calcining ores or other materials by the methods and apparatus we
have herein-before described, no manual labour is required other than
in the firing of the furnace and in charging and discharging, and in
the latter operations it is only required so far as is necessary to make
the requisite adjustment of the discharging and levelling plates.
We should here observe that we are aware that a revolving bottom
has been applied to calcining furnaces and used particularly in the
calcination of tin ores with a constant stream of ore falling on a raised
centre and directed towards the circumference by a series of fixed
parallel plates, and we therefore do not claim the revolving bed or fixed
parallel plates for discharging; but what we consider novel and original,
and therefore claim as constituting the Invention secured to us by the
said herein-before in part recited Letters Patent are, the combination
and arrangement of parts and mechanism in the construction of furnaces
and the methods of working the same, substantially as and for the
purposes herein-before described and set forth, or any mere modifications
thereof.
In witness whereof, we, the said Thomas Gibb and Charles
Gelstharp, have hereunto set our hands and seals, this Twentieth
day of April, in the year of our Lord One thousand eight hundred
and seventy.