IMPROVEMENTS IN FURNACES FOR OBTAINING LEAD FROM ITS ORES
Year: 1869

page_text: LETTERS PATENT to George Metcalf, of the Pertusola Foundry, near
Spezia, in the Kingdom of Italy, Foundry Foreman, for the In-
vention of "IMPROVEMENTS IN FURNACES FOR OBTAINING LEAD FROM ITS
ORES."
Sealed the 18th January 1870, and dated the 18th August 1869.
PROVISIONAL SPECIFICATION left by the said George Metcalf at the
Office of the Commissioners of Patents, with his Petition, on the
18th August 1869.
I, GEORGE METCALF, of the Pertusola Foundry, near Spezia, in the
Kingdom of Italy, Foundry Foreman, do hereby declare the nature of
the said Invention for "IMPROVEMENTS IN FURNACES FOR OBTAINING LEAD
FROM ITS ORES," to be as follows:-
The object of this Invention is to expedite and facilitate the opera-
tion of obtaining lead from its ores. For this purpose a furnace is
used divided longitudinally for a portion of its length by a vertical
partition or wall extending upward to the roof or crown of the furnace,
but not extending to the grate or fire-bars, so that a chamber with a bed

page_text: is left near the grate or fire-bars extending the entire breadth of the
furnace and having no partition at that part. The compartments or
passages formed by the partition have at their ends registers, doors, or
arrangements for opening and closing communication between them, and
ducts or uptakes leading or branching thence into the chimney or shaft.
The charges are placed in the compartments or passages thus formed,
and are gradually fed forward to the fire chamber or bed in front of the
fire-bars. The draft is shut off from each compartment or passage
alternately, one being open to the chinney while the other is closed, so
that while one set of charges is exposed to the free current of flame or
aeriform or gaseous products of combustion rushing from the fire through
the passage or compartment towards the chimney, the other set of charges
or those in the other passage are subjected only to the action of dead
heat because the draft apertures at the end are closed. Drafts of air
may be delivered- through, over, and transversely of the fire bridge or
bed. The lead (as it is fed in) dries and becomes calcined and wholly
or partially desulphurized as it is passed gradually along the chamber,
and at length it reaches the bed or chamber in front of the fire-bars.
The greatest portion is then removed in a state of slag or agglomeration
through an opening in the furnace fitted (when opened) with a re-
movable spout or shoot, down which the slag or agglomeration descends
into a waggon, and is run off therein to a blast furnace in order to be
again subjected to heat for metallurgical purposes.
In my furnace less heat is required, and less fuel is expended, and the
furnace is better preserved. The lead that remains in the furnace is
removed by tapping the furnace and allowing the molten lead to run out.
It is preferred to construct the bed of the furnace of a curved form.
In order to get out all the lead in case of the furnace bed leaking or
becoming destroyed a false door is used parallel with the tapping door
and screwed thereto, the interval between the two doors or plates being
filled with bone ash. If the furnace, bed gets destroyed or leaks and
the lead runs through it can be withdrawn through the false door.
In order that the nature of the Invention may be well understood, I
add that its main essential features consist,--
First. In constructing a furnace with a longitudinal partition extending
from the door end of the furnace towards but not up to the grate, thereby
forming, two, passages for the aeriform products of combustion for the
purpose described, and leaving a bed or space near the grate or fire-bars..

page_text: Secondly. In using a false or supplementary door for the purpose.
described, the space between the two doors being filled with some non-.
conductor of heat.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said George Metcalf in the Great Seal Patent Office
on the 18th February 1870..
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
METCALF, of the Pertusola Foundry, near Spezia, in, the Kingdom of
Italy, Foundry Foreman, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing, date the Eighteenth day of August, 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 me, the said George Metcalf, Her special licence
that I, the said George Metcalf, my executors, administrators, and
assigns, or such others as I, the said George Metcalf, 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 "IMPROVEMENTS IN
FURNACES FOR OBTAINING LEAD FROM ITS ORES," upon the condition (amongst
others) that I, the said George Metcalf, my executors or administrators,
by an instrument 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 George Metcalf, do hereby
declare the nature of the said Invention, and in what manner thie.
same is to be performed, to be particularly described and ascertained.
in and by the following statement thereof, reference being had to the
accompanying Drawings, and to the letters and figures marked thereon,
that is to say:-

page_text: The object of this Invention is to expedite and facilitate the operation
of obtaining lead from its ores. For this purpose a furnace is used
divided longitudinally for a portion of its length by a vertical partition
or wall extending upward to the roof or crown of the furnace, but no
extending to the grate or fire-bars, so that a chamber with a bed is left
near the grate or fire-bars extending the entire breadth of the furnace
and having no partition at that part. The compartments or passages
formed by the partition have at their ends registers, doors, or arrange-
ments for opening and closing communication between them, and ducts
or uptakes leading or branching thence into the chimney or shaft. The
charges are placed in the compartments or passages formed by the
partition, and are gradually fed forward to the fire chamber or bed in
front of the fire-bars. The draft is shut off from each compartment or
passage alternately, one compartment or passage being open to the
chimney while the other is closed, so that while one set of charges are
exposed to the free current of flame or aeriform or gaseous products of
combustion rushing from the fire through the passage or compartment
towards the chimney, the other set of charges or those in the other
passage are subjected only to the action of dead heat, because the draft
apertures at the end are closed. The lead as it is fed in dries and becomes
calcined and wholly or partially desulphurized as it is passed gradually
along the chamber, and at length it reaches the bed or chamber in front
of the fire-bars. The greatest portion is then removed in a state of
slag or agglomeration through an opening in the furnace fitted (when
opened) with a removeable spout or shoot, down which the slag or
agglomeration descends into a waggon, and is run off therein to a blast
furnace in order to be again subjected to heat for metallurgical purposes.
In my furnace less heat is required, and consequently less fuel is
expended, and the furnace is better preserved. The lead that remains
in the furnace is removed by tapping the furnace and allowing the
molten lead to run out.
It is preferred to construct the bed of the furnace of a peculiar curved
form. In order to get out all the lead in case of the furnace bed leaking
or becoming destroyed a false door is used parallel with the tapping
door, and screwed thereto, the interval between the two doors or plates
being filled with bone ash or similar non-conductor of heat. Thus if the
furnace bed gets destroyed or leaks and the lead runs through it the

page_text: lead or metallic product of the operation can be withdrawn through the
false door.
In order that the nature of the Invention may be well understood;.
I add that its main essential features consist,―
First. In constructing a furnace with a longitudinal partition extend-
ing from the back end of the furnace towards but not up to the grate,.
thereby forming two passages for the aeriform products of combustion.
for the purpose described, and leaving a bed near the grate or fire-bars.
Secondly. In using a false or supplementary door for the purpose
described, the space between the two doors being filled with some non-
conductor of heat.
The accompanying Drawings exemplify a furnace constructed accord-
ing to my Invention.
Figure 1 is a side elevation of a furnace with my improvements
applied thereto; Figure 2 is a horizontal section; Figure 3 is a transverse
section through the plane of the tapping hole; Figure 4, longitudinal
vertical section; Figure 5, transverse section shewing hopper; Figures 6
and 7, detached views, Figure 6 shewing tapping plates, Figure 7,
view of bridge plate Q.
A, A, walls of the furnace; B, wall or partition dividing a portion of the
furnace into two passages or compartments C and D; E, tapping passage;
F, space below the bed; G, tunnel; H, smelting bed; I, agglomeration
bed; J, desulphurizing or oxydizing bed; K, drying off bed; G*, G*,
tunnels through the furnace; N, hopper; O, fire-door; P, P*, tapping
plates or doors, Figure 6; Q, bridge plate; R, tapping hole; S, spout for
removing the charge out of the furnace; T, pot to receive the discharged
lead; m, m, working doors; X, fire hole; U, ash-pit; V, fire-bridge. The
partition B is a wall which extends from the end of the furnace to the
smelting bed or chamber H, so that it divides the furnace for a portion
of its length into two longitudinal passages or compartments C, D; the
bottom of these passages forms the beds I, J, K. The wall B extends
from the floor to the crown of the furnace. The bed H extends the
whole breadth of the furnace, there being no partition B at that part.
9, g*, are registers at the ends of the passages C, D, which open and
close communication between those passages and the ducts or up-
takes y, y, which lead into the chimney or shaft. The charges are
placed in the compartments or passages C, D, and are gradually fed

page_text: forward to the bed E, and the draft doors are alternately opened and
closed so as to open and close each passage C, D, to the chimney
alternately, so that while the charge in one passage (say,. C,. for instance):
is exposed to the current of the flame and hot aeriform products of
combustion rushing from the fire-bars towards the chimney, the charge
in the other passage (say, D, for instance) is subjected to the action of
dead heat because its draft door is closed, and so on alternately. The
material in its passage thus dries and becomes calcined and wholly or
partially desulphurized as it is fed along the furnace. Drafts of air may
be injected through, over, and transversely of the fire-bars through air
holes or apertures. There may be a current of air across the top of
the bridge from end to end of the furnace, and a draft of air through
the bridge, which is made hollow for that purpose. Side currents of air
may be driven in on each side of the furnace between the smelting.
bed H and the agglomeration bed I. The greatest portion of the lead
is then removed in a state of slag, or as it is called "agglomeration,"
through the opening R, which can be plugged when not required, but
which when opened is fitted with a removeable spout S, down which the
slag or "agglomeration" descends into a vessel T mounted on a waggon,
and it is run off therein to a blast furnace of ordinary description..
Figure 4 shews the curved form of furnace bed D, which I prefer to
adapt.
Figure 6 shews the combined tapping plates or doors P, P*; the latter
is screwed to and parallel with the plate P. These plates are not close
together, but there is a small space or interval between them which is
filled with bone ash. If the furnace bed should be destroyed or impaired
so as to leak and the lead should run through it to the bottom of the
furnace below the bed it can be withdrawn through the false door P*.
The furnace constructed with the longitudinal wall or partition as
above-described is especially suited for treating that class of lead ore
which contains a large proportion of sulphur. In this furnace a larger
quantity of mineral can be worked (with the same amount of fuel)
than in furnaces of ordinary construction.
Having now described the nature of the said Invention, and in what
manner the same may be performed, I declare that I claim as con-
stituting my Invention,―
First. The employment or application of a longitudinal wall or
partition within the furnace extending for a portion of the length of the

page_text: furnace so as to form two passages, substantially in the manner and for
the purpose herein-before described.
Second. The employment of two tapping plates or doors in com-
bination, that is to say, a second tapping door or plate in combination
with the main tapping plate or door, substantially in the manner and for
the purpose described.
Third. The general arrangement and combination of parts constituting
my improved furnace herein-before described and exemplified in the
accompanying Drawings.
In witness whereof, I, the said George Metcalf, have hereunto set
my hand and seal, this Twenty-sixth day of January, in the
year of our Lord One thousand eight hundred and seventy.
Witnesses,
G. B. ROLLA,
Testimonio.
and
GEORGE SPARKS,
Golfo di Spezia, Italia.
GEORGE METCALF. (L.S.)