IMPROVEMENTS IN CALCINING ORES, MINERALS, AND OTHER SUBSTANCES, AND IN FURNACES THEREFOR
Year: 1868

page_text: LETTERS PATENT to Theodore Merz, Chemist, of Hebburn, in the
County of Durham, and George Thomson, Chemist, of Pelaw-Main,
in the same County, for the Invention of "IMPROVEMENTS IN CALCINING
ORES, MINERALS, AND OTHER SUBSTANCES, AND IN FURNACES THEREFOR."
Sealed the 6th April 1869, and dated the 10th October 1868.
PROVISIONAL SPECIFICATION left by the said Theodore. Merz and,
George Thomson at the Office of the Commissioners of Patents, with
their Petition, on the 10th October 1868.
We, THEODORE MERZ, Chemist, of Hebburn, in the County of Durham,
and GEORGE THOMSON, Chemist, of Pelaw-Main, in the same County,
do hereby declare the nature of the said Invention for "IMPROVEMENTS IN
CALCINING ORES, MINERALS, AND OTHER SUBSTANCES, AND IN FURNACES THEREFOR,"
to be as follows, that is to say:-
This Invention consists in applying a revolving furnace such as is
used in alkali works for transforming sulphate into carbonate of soda,

page_text: to the calcination of ores, minerals, and other substances, especially
copper ores, or copper ores mixed with salt, with the modification that
the revolving furnace is heated by a combustible gas such as coal gas
or carbonic oxide instead of by fuel in the ordinary manner.
The
object of this modification is to obviate the prejudicial influence which
the presence of coal smoke is known to exert on the volatilised compounds
of copper, by making them incondensable.
The Invention also comprises the applying of the said revolving
furnace to other reducing or oxidising processes, as for instance to the
reducing of oxide of iron into spongy iron, or to the reducing of
sulphate of baryta into sulphide of barium.
For the purpose of calcining or heating ores and other substances,
and in case the flame of the gas passing over the heated substance
might prove prejudicial to the process the flues are separated from the
interior of the furnace in the following manner, converting thereby
the said furnace into a closed revolving furnace. Instead of lining
the cylinder with solid fire-bricks hollow fire-blocks are used, and are
joined together in such a way as to leave a number of channels or
flues in the lining of the cylinder. These flues will allow a gas or
common coal flame to pass through, and will thus raise the heat in the
interior of the cylinder to any desired degree, without bringing the
contents in contact with the fire gases. This arrangement will likewise
admit of connecting the interior of the cylinder by a separate flue
with any convenient condensing apparatus or of passing a current of
steam or any other gas into the furnace, and in all these cases the
contents of the furnace will not be exposed to either the reducing or
oxidising influence of the fire gases.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Theodore Merz and George Thomson in the Great
Seal Patent Office on the 8th April 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, THEODORE
MERZ, Chemist, of Hebburn, in the County of Durham, and GEORGE
THOMSON, Chemist, of Pelaw-Main, in the same County, send greeting.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, THEODORE
MERZ, Chemist, of Hebburn, in the County of Durham, and GEORGE
THOMSON, Chemist, of Pelaw-Main, in the same County, send greeting.

page_text: WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Tenth day of October, in the year
of our Lord One thousand eight hundred and sixty-eight, in the thirty-
second year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto us, the said Theodore Merz and George Thomson, Her
special licence that we, the said Theodore Merz and George Thomson, our
executors, administrators, and assigns, or such others as we, the said
Theodore Merz and George Thomson, our 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 "IMPROVEMENTS IN CALCINING ORES,
MINERALS, AND OTHER SUBSTANCES, AND IN FURNACES THEREFOR," upon the
condition (amongst others) that we, the said Theodore Merz and George
Thomson, our executors or administrators, by an instrument in writing
under our, 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 we, the said Theodore Merz and George Thomson,
do hereby declare the nature of our said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement in writing, reference being had to the
accompanying Drawings, that is to say:-
Our said Invention consists in applying a revolving furnace, such as
or similar to that used in alkali works for transforming sulphate into
carbonate of soda, to the calcination of ores, minerals, and other sub-
stances, especially copper ores, or copper ores mixed with salt or other
suitable chlorides, with the modification that we obviate the prejudicial
influence which the presence of coal smoke exerts on the volatilised
compounds of copper, and which renders them incondensable, by
employing smokeless fire gases or flame for heating the furnace, which
may be obtained by burning a suitable combustible gas, such as coal gas
or carbonic oxide, or by burning coal or other solid fuel in a furnace
arranged so as to insure the absence of smoke.

page_text: Our said Invention also comprises the applying of the said revolving
'furnace to other reducing or oxidising processes, as for instance to the
reducing of the oxide of iron into spongy iron, or to the reducing of
sulphate of baryta into sulphide of barium; also a mode of constructing
the revolving furnace with flues arranged to separate the fire gases or
flame from the substances in the furnace when the passing of the gases
or flame directly over the substances would have a prejudicial effect.
And in order that our said Invention and the manner of performing
the same may be properly understood, we have hereunto appended a
Sheet of explanatory Drawings representing two modifications of
revolving furnace, and to be herein-after referred to in particularly
describing our improvements.
Figure 1 is a longitudinal vertical section of one form of revolving
furnace to be used in carrying out our Invention. It consists of a
cylindrical shell 1 made of common boiler plate and lined with fire-
brick 2; it is encircled by hoops 3, made by preference of cast steel,
and by means of them rests on antifriction rollers 4, whilst it is turned
about its horizontal axis by means of a screw 5, actuated in any con-
venient way and gearing with a toothed ring 6, fixed on the cylinder.
The ends of the cylinder are closed with the exception of central holes,
that, 7, at one end being for the admission of fire gases or flame, and
that, 8, at the other end for communication with a flue 9, by which
volatile matters pass off; in connection with this flue 9 we propose
to build a large chamber for the deposit of dust carried out of the furnace
by the gaseous current, and in some cases we lead the gaseous products
through a condensing or absorbing tower, or into any suitable condenser.
We prefer to heat the interior of the cylinder by means of gas capable
of burning without smoke, particularly when calcining copper ores mixed
with salt; but we do not restrict ourselves to any particular mode of
generating the gas, and this may be done either in a separate gas pro-
ducer, from which the gas may be conveyed by tubes or flues to the
inlet 7, where the air necessary for combustion is allowed to mix with
it and where it is ignited, or the gas may be formed and ignited in an
immediately adjacent furnace of any convenient known kind which is
capable of being worked without producing smoke. At the same time
we must observe that in some cases the presence of smoke may not be
prejudicial, and in such cases the fire gases may be generated in a

page_text: furnace of the simplest construction. For the purpose of charging and
emptying the cylinder a hole 10 is made in its side, and is turned to the
upper or under side as required, whilst it is of course closed when a
charge is being operated upon. To facilitate the drawing of a charge, as
also to admit of the close observation of the process, we propose to form
a series of small holes 11 in the cylinder ends, such holes being fitted
with doors. Through these holes 11 rakes may be introduced for raking
the calcined ore towards the outlet 10 when removing a charge. In
order to increase the effect of the rotation of the cylinder, and to obtain
a more perfect turning over of the contents of the furnace, we form in the
fire-brick lining 2, fire-brick projections, and we dispose them angularly
with respect to the cylinder's axis, so that by making the cylinder
revolve alternately in opposite directions the ores are worked backwards
and forwards from end to end, thereby mixing together the hotter and
cooler portions and equalising the temperature which would otherwise
vary in different parts of the charge, particularly when the cylinder is
made of any considerable length.
We do not limit or restrict ourselves to the precise proportions or
arrangements of the apparatus shown in the accompanying Drawing, but
intend to modify these to suit the materials to be operated upon and the
action desiderated in each case. For instance, when working ores com-
paratively rich in sulphur, or generally when the object of the calcination
is to promote a rapid oxidising action, it may be advantageous to present
a more extended surface to the flame by lengthening the cylinder
without increasing its diameter, additional supporting hoops and anti-
friction rollers being provided, as also more doors for charging and
discharging if desired. In calcining copper or other ores with salt or
other suitable chlorides it is not essential that the chloride be added in
the solid state; it may be conveniently and beneficially added in a state
of solution or partial solution, and it may be injected as spray when the
ore has acquired a red heat and whilst the cylinder is rotating. The
chloride may be injected very conveniently through a small hole formed
in the elbow of the flue at 12.
Figure 2 is a longitudinal vertical section of a modification of the
revolving furnace to be used when it is desired to avoid the immediate
contact of the fire gases or flame with the ores or substances to be
operated upon. This furnace differs from that shown in Figure 1 and

page_text: And, 3. The calcining of copper ores mixed with salt or other chlorides
n a revolving furnace, substantially as herein-before described.
In witness whereof, I, the said Theodore Merz, on behalf of myself
and the said George Thomson, have hereunto set my hand and
seal, this Seventh day of April, in the year of our Lord One
thousand eight hundred and sixty-nine.
Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
THEODORE MERZ. (L.8.)