IMPROVEMENTS IN ZINC RETORT FURNACES
Year: 1859

page_text: LETTERS PATENT to John Darlington, of No. 36, Cannon Street, in the
City of London, County of Middlesex, Mining Engineer, for the Invention
of "IMPROVEMENTS IN ZINC RETORT FURNACES."
Sealed the 27th October 1859, and dated the 30th April 1859.
PROVISIONAL SPECIFICATION left by the said John Darlington at the
Office of the Commissioners of Patents, with his Petition, on the
30th April 1859.
I, JOHN DARLINGTON, of No. 36, Cannon Street, in the City of London,
County of Middlesex, Mining Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN ZINC RETORT FURNACES," to be as
follows:-
My improvements consist in constructing zinc retort furnaces in such a
manner, as to cause the retorts to be heated by means of a fire-place,
so arranged that the fuel employed shall be rendered incandescent, either by a
blast of cold air, or by air previously heated, and not by a natural draft, as at
present. The blast of hot or cold air may be produced by means of fans,
cylinders, or any other suitable mechanical appliance. When I employ coal,
it may be caked or coked during its passage into the fire-place, and the slags,
clinkers, or other matter resulting from the combustion of such or any other
fuel may naturally, or by the addition of suitable fluxes, flow through a tap-
hole, or be withdrawn at intervals through doorways or passages made in the
furnace for that purpose.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Darlington in the Great Seal Patent Office on the
28th October 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN DAR-
LINGTON, of No. 86, Cannon Street, in the City of London, County of
Middlesex, Mining Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirtieth day of April, in the year of our Lord
One thousand eight hundred and fifty-nine, in the twenty-second year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said John Darlington, Her special license that I, the said John Dar-
lington, my executors, administrators, and assigns, or such others as I, the
said John Darlington, my executors, administrators, 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 "IMPROVE-
MENTS IN ZINC RETORT FURNACES," upon the condition (amongst others) that
I, the said John Darlington, my executors or administrators, by an instru-
ment in writing under my, or their, or one of their hands and seals, 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 I, the said John Darlington, do hereby declare
the nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, reference being had to the accompanying Drawings (that is
to say):
My improvements consist in constructing zinc retort furnaces in such
manner as to cause the retorts to be heated by means of a fire-place so
arranged that the fuel employed shall be rendered incandescent, either by a
blast of cold air, or by air previously heated, and not by a natural draught as
at present. The blast of hot or cold air may be produced by means of fans,
cylinders, or any other suitable mechanical appliance. When I employ coal,
it may be caked or coked during its passage into the fire-place, and the slags,
clinkers, ash, or other matter, resulting from the combustion of such or any.
other fuel may naturally, or by the addition of suitable fluxes, flow through a

page_text: tap-hole, or be withdrawn at intervals through doorways or passages made in
the furnace for that purpose..
In carrying my plan into operation, I prefer using the Belgian or Liege
cylindrical pot zinc furnace; but the plan is equally applicable to any kind of
furnace, in which the zinc ore is to be reduced in close chambers. The
application of my improvements to zinc retort or muffle furnaces, is shewn in
the Drawings herein-after described, and is as follows:-
Figure 1 represents a transverse section of a zinc retort or muffle furnace.
It will here be perceived that the fire-bars marked A, instead of forming part
of an open draught grate, such as is commonly employed for zinc furnaces, are
enclosed. Beneath the bars A, I construct an air chamber B. Apertures are
formed in this air chamber, in each of which I place a tuyere or blowing-
nozzle C. The number of such tuyeres or blowing nozzles is optional;
it must be decided by the exigencies of each particular furnace. Through
each of these tuyeres hot or cold air is blown or otherwise forced. The air
chamber B serves also as an ash-pit. An opening is made in one side of this
chamber, in which is fixed an air-tight door or plate D. Such air-tight doors
or plates may be fixed in several sides of the chamber, if more than one
is found necessary.
At suitable intervals these doors are opened, and the ash,
cinders, slags, or clinkers, which fall from the fire-bars are withdrawn.
Above the fire-place, and immediately beneath the bottom row of pots E,
rectangular or other shaped openings F are made, through which the fuel is
admitted to the fire-place. When coal is used, it is placed in the hopper G,
but is not allowed to fall immediately upon the fire, being retained near the
entrance until it becomes caked, when it is made to pass into the fire.
Figure 2 represents a transverse section of a zinc retort or muffle furnace,
in which fire-bars are dispensed with. The fire-place H, under the pots
or muffles, is constructed with a semi-elliptical or other shaped bottom, into
which the fuel is introduced at J, in the manuer herein-before described.
Combustion is maintained by means of blast tuyeres K, which are inserted in
holes formed near the bottom of the fire-place. Before the fuel is introduced
into the fire-place, if necessary, proper fluxes are mixed with it in order to
liquify the earthy or mineral matter which it may contain. The liquid slag
which thus may be produced is withdrawn at intervals through one or more
air-tight doors or plates L, or it may be made to flow continuously through
one or more discharge holes.
Having now described the nature of my Invention, and the manner in
which it may be carried into effect, I wish it to be understood that the
arrangement above described may be varied in form and detail, without

page_text: departing from the peculiar feature of my Invention, as will be evident to any
person conversant with the structure of furnaces..
And I hereby declare that what I claim as the Invention intended to be
secured by the said Letters Patent, is the construction of retort or muffle
furnaces, used for the reduction of zinc ores, or other products containing
zinc, whereby hot or cold air may be forced or diffused through and among
the fuel employed so as to render the same incandescent, and coal may be
supplied at the side in a caked or coked state, as above described.
In witness whereof, I, the said John Darlington, have hereunto set my
hand and seal, this Seventeenth day of October, in the year of our
Lord One thousand eight hundred and fifty-nine.
JOHN DARLINGTON. (L.S.)