IMPROVE- MENTS IN SEPARATING SILVER FROM ARGENTIFEROUS LEAD, IN PURIFYING LEAD, AND IN APPARATUS FOR THE SAME
Year: 1868

page_text: LETTERS PATENT to André Giraud, of Gray's Inn Road, in the
County of Middlesex, Gentleman, for the Invention of "IMPROVE-
MENTS IN SEPARATING SILVER FROM ARGENTIFEROUS LEAD, IN PURIFYING
LEAD, AND IN APPARATUS FOR THE SAME."
Sealed the 20th April 1869, and dated the 24th October 1868.
PROVISIONAL SPECIFICATION left by the said André Giraud at the
Office of the Commissioners of Patents, with his Petition, on the.
24th October 1868.
I, ANDRÉ GIRAUD, of Gray's Inn Road, in the County of Middlesex,
Gentleman, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN SEPARATING SILVER FROM ARGENTIPEROUS LEAD, IN PURIFYING
LEAD, AND IN APPARATUS FOR THE SAME," to be as follows:-
I commence with extracting as completely as possible by any of the
ordinary methods the antimony which may be contained in the lead.
Immediately afterwards I place the lead in any suitable vessel, but by.
preference I employ for this purpose a melting pan, (herein-after called
boiler,) to which I adapt an opening at its base in order to allow the

page_text: be set on an ordinary furnace, but by preference the furnace should be
provided with a movable grate, which will facilitate the instantaneous
extinction of the fire.
For greater clearness in my description I shall divide my boilers com-
posing cach range into the following order, that is to say-First boiler
containing the argentiferous lead freed from antimony; second boiler
reserved for the rich litharge or dross; and third boiler for the extra
rich skimmings of the litharge or dross. Although I here mention three
boilers for the purpose of exemplifying my process, I do not limit
myself to that number. I light up the furnace of the first boiler, and
when the lead therein is reduced to a perfect state of fusion I increase
the intensity of the fire, and then I add to the fused metal a sufficient
quantity of zinc, the proportion varying according to the richness of the
lead previously ascertained by assay. I immerse the zine by means of
an apparatus next herein-after described, and which I call a "mixer."
This apparatus consists of a box or case divided in two parts, united
by bolts or otherwise. The box or case is perforated and attached to a
metallic spindle provided with radiating branches or paddles to promote
the mixture of the zinc with the fused metal. But I do not confine thic
arrangement of vanes or paddles to the simple disposition of projecting
or horizontal arms or branches; any system of horizontal or vertical
vanes or paddles working from or in combination with the spindle and
box may be employed, as well as any variation in the arrangement of
the box or case attached to the spindle. The spindle with the box
attached containing the zine is adequately sunk in the molten metal,
and supported at the top end by one or more riding bars set on the rim
of the boiler, or by any other method of vertical suspension. Thereupon
a revolving motion is communicated to it, and the zinc fusing and
escaping from the box in small particles passes through the mass of lead
in agitation and arrives insensibly at the surface, drawing with it a great
part of the silver. When the mixture of the zinc with the lead is ter-
minated the "mixer" is withdrawn and the fire suddenly extinguished,
continuing for some time longer to stir the molten metal. It is then
necessary to watch the metal and take advantage of the favourable
moment for lightly and dextrously skimming the surface, taking care to
remove as little as possible of the lead. The produce of this skimming,
which is called argentiferous dross or rich litharge, is thrown into the

page_text: second boiler in order. to be. there treated separately, which will be the
subject of subsequent description. The fire of the first, boiler. is now
re-kindled for the purpose of re-melting the metal therein contained..
The "mixer." is introduced a second time charged with zinc, and the
operation above described is repeated exactly in the same way until it.
is ascertained by assay that the silver has been entirely extracted..
Commonly after two such operatious a third will be needless, inasmuch.
as the precious metal will be altogether or almost entirely extracted:
from the lead. The purification of the lead is, then to. be offected, so.
that it may be freed not only from the zinc, but even from other foreign,
matters. For that purpose a brisk fire is re-kindled under the first
boiler, which is hermetically closed by the aid of a cap or cover, which
I prefer should be somewhat convex, and securely fastened to the rim
of the boiler by keys or otherwise. In the cover two apertures.should
be contrived, one for the passage of a pipe leading steam into the-metal
in fusion, and the other larger for the escape of the steam carrying with
it a great quantity of oxide of zinc and other matters. To this second
opening is adapted an external tube communicating with a condensing
chamber or receptacle, and conveying thither the oxide of zine and other
matters. This chamber should be divided into several compartments
and conveniently- ventilated: The steam pipe is sunk in the molten
metal to such a depth that the steam may spread throughout the.
mass of metal. If the boiler be very large and one jet of steam insuffi-.
cient to reach the zinc in every part, the principal pipe may be fitted:
with several auxiliary pipes which will permit the steam to penetrate
quite through the molten lead. The higher the temperature of the.
steam the more prompt and efficacious will be its effect. It will be.
prudent to adapt to the steam pipe externally two taps, one for regu
lating the admission of steam into the metal, the other to be first
opened to let off any water collected in the pipe, which will prevent any
spattering of the fused metal. I do not restrict myself to the use of
taps; any other available means of regulating the passage of the steam,
and for drawing off the moisture and precluding condensation may be
employed. When the steam shall have been introduced into the molten
lead it will be desirable to ascertain when the oxidation is completely.
terminated. To that end a valve or tap or other contrivance of the kind.
with any suitable appliances is fitted to the escape tube to permit of
seeing whether the steam passes in its natural state clear of oxides, or other
matter, and then its function being terminated the steam is suppressed.

page_text: The cover with its appliances is then removed, and all the oxides and
other matters which float on the surface are very lightly skimmed off,
carefully avoiding the metal as much as possible. Now that the lead
is entirely purified it is poured in the usual way or run out into moulds
in the shape of pigs or ingots or otherwise. If the latter operation be
employed the conduit by which the lead is run off should be heated by
an appliance in the nature of a chafing dish or brazier or otherwise, for
the purpose of preventing premature cooling. For conveyance of the
moulds and in order to expedite that operation I employ by preference,
but not exclusively, a rail or tramway with appliances for transmission,
which I call port moulds or little trucks.
When by the preceding operations several times repeated I have
obtained a sufficient quantity of argentiferous dross or rich litharge to
fill my second boiler, I proceed then to treat it in the following
manner: These rich skimmings or dross composed principally of lead,
silver, and zinc should be reduced to fusion in order to receive the
steam with a view to oxidize and remove the zinc and other matters,
When this is effected the metal remaining may he refined by cupellation
immediately afterwards, inasmuch as it would contain considerably less
lead than after the usual Pattinson process; but it is preferable to treat
it as next herein-after explained.
"
I light up the furnace under the second boiler containing the rich
litharge, and when the contents are in perfect fusion I introduce a
"mixer without a box, but provided with radiating vanes or paddles
suspended and worked in the same manner
as the "mixer" first
described, in order to amalgamate the lead, silver, and zinc which
compose the contents of the boiler. I then extinguish the fire, and I
continue to skim as long as possible all that coagulates on the surface,
carefully casting into the third boiler this new litharge, which I call
"extra rich." If the lead, or rather the litharge or dross that remains
in the second boiler still contain a certain quantity of silver, I bring it
again to a state of fusion. I introduce this time a "mixer" having a
perforated box attached with a small quantity of zinc in proportion to
the requirements, and I effect a complete mixture as herein-before
described. Then I draw the furnace and I again skim the coagulated
surface, of which the skimming is to be taken to the third boiler. If
the metal, or rather the litharge or dross that remains in the second
boiler, contain still a quantity of silver nearly equal to that of the

page_text: primitive silver lead, more or less, it may be mixed up with other metal
prepared to undergo treatment in the first boiler, as herein-before
described. In case however it is much richer than the primitive silver
lead it is better to re-melt it again in the second boiler, and repeat the
last preceding operation with a "
operation with a "mixer," and box for the addition of
the adequate proportion of zinc. Often after the last operation the lead
remaining in this second boiler contains a very small and nearly insig-
nificant portion of silver, so small in fact that it may be disregarded. Then
the contents of this boiler is re-heated to fusion with a brisk fire, and the
lead is purified by the aid of one or more jets of steam, cleared of oxide,
and skimmed, and the remaining metal is subsequently poured or run
into moulds. As to the extra rich litharge or dross placed in the third
boiler, when a sufficient quantity is collected it is reduced to a perfect
state of fusion, and with the application of steam in a manner similar
to that hercin-before described, it is freed from the zinc and other
matters. Immediately after this operation the product may be taken to
the cupel furnace, or otherwise disposed of for the purpose of obtaining
the silver in a state of purity by any approved method. By continuing
these operations, employing small pots, by preference somewhat of the
form of crucibles, and with the modifications in manipulation self-
evident to a skilful workman, the silver may be freed from alloy or
impurities, so that it may remain in a state of purity or nearly so.
When a súfficient quantity of oxide and other matters of a nature to be
converted to useful purposes is collected suitable means are adopted to
utilize the same.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said André Giraud in the Great Seal Patent Office on
the 23rd April 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ANDRÉ
GIRAUD, of Gray's Inn Road, in the County of Middlesex, Gentleman,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fourth 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 suc-

page_text: cessors, give and grant unto me, the said André Giraud, Her special
licence that I, the said André Giraud, my executors, administrators,
and assigns, or such others as I, the said André Giraud, my cxc-
cutors, 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 SEPARATING SILVER FROM ARGENTIFEROUS LEAD, IN PURIFYING LEAD, AND IN
APPARATUS FOR THE SAME," upon the condition (amongst others) that I,
the said André Giraud, 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 André Giraud, do hereby declare
the nature of my said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and
by the following stateinent, reference being had to the accompanying
Drawings, and to the letters and figures marked thereon (that is to
say) :-
:-
According to my Invention I commence with extracting as completely
as possible by any of the ordinary methods the antimony which may be
contained in the lead; immediately afterwards I place the lead in any
suitable vessel, but by preference I employ for this purpose a melting
pan (herein-after called boiler) to which I adapt an opening at its base
or bottom in order to allowed the fused metal to be run off as required.
This melting pan or boiler may be set on an ordinary furnace, but by
preference the furnace should be provided with a movable grate which
will facilitate the instantaneous extinction or removal of the fire.
For greater clearness in my description I shall divide my boilers
composing each range into the following order, that is to say-First
boiler containing the argentiferous lead freed as before mentioned from
antimony; second boiler, reserved for the rich litharge or dross; and
third boiler for the extra rich skimmings of the litharge or dross.
Although I here mention- three boilers for the purpose of exemplifying

page_text: my process I do not limit myself to that number. The operations herein-
after described as to be effected in one or more of the said boilers may he
performed in any number of boilers appropriately disposed for the
purpose; for example, that part of my Invention which is described as
applicable to the first boiler may be divided, and the lead may be run
from one to another as shown by the accompanying Drawings, or the
treatment described as to be effected in two or more of the said boilers
may be confined to one or two boilers. I light up the furnace of the
first boiler, and when the lead therein is reduced to a perfect state of
fusion I increase the intensity of the fire, and then I add to the fused
metal a sufficient quantity of zinc, the proportion varying according to
the richness of the lead previously ascertained by assay. I immerse the
zine by means of an apparatus next herein-after described, and which I
call a "mixer." This apparatus consists of a box or case divided in two
or more parts united by bolts or otherwise. The box or case is perforated.
and attached to a metallic spindle provided with radiating branches or
paddles to promote the mixture of the zinc with the fused metal; but I
do not confine the arrangement of vanes or paddles to the simple dis-
position of projecting or horizontal arms or branches; any system of
horizontal, vertical, or inclined vanes or paddles working from or in
combination with the spindle or box may be employed as well as any
variation in the arrangement of the box or case attached to the spindle.
The spindle with the box attached containing the zinc is adequately
sunk in the molten metal and supported at the top end by one or more
riding bars set on the rim of the boiler or by any other method of vertical
suspension; thereupon a revolving motion is communicated to it, and the
zinc fusing and escaping from the box in small particles or streams passes
through the mass of lead in agitation, and in a great measure arrives
gradually at the surface, drawing with it a considerable part of the silver.
When the mixture of the zinc with the lead is terminated the "mixer"
is withdrawn and the fire suddenly extinguished or removed, continuing
for some time longer to stir the molten metal. It is then necessary to
watch the metal and take advantage of the favorable moment for lightly
and dexterously skimming the surface, taking care to remove as little as
possible of the lead. The produce of this skimming, which is called
argentiferous dross or rich litharge, is thrown into the second boiler in
order to be there treated separately, which will be the subject of sub-
sequent description. The fire of the first boiler is now rekindled for
the purpose of remelting the metal therein contained, the "mixer" is

page_text: introduced a second time charged with zinc, and the operation herein-
before described is repeated exactly in the same way until it is ascertained
by assay that the silver has been entirely extracted. Commonly after
two such operations a third will be needless, inasmuch as the precious
metal will be altogether or almost entirely extracted from the lead.
The purification of the lead is then to be effected, so that it may be freed
not only from the zinc but even from other foreign matters. For that
purpose a brisk fire is rekindled under the boiler containing the metal
to be purified, and which is hermetically closed by the aid of a cap or
cover, which I prefer should be somewhat convex, and securely fastened
to the rim of the boiler by keys or otherwise. In the cover two apertures
should be contrived, one for the passage of a pipe leading steam into the
metal in fusion, and the other larger for the escape of the steam, carrying
with it a great quantity of oxide of zinc and other matters. To this
second opening is adapted an external tube communicating with a con-
densing chamber or receptacle, and conveying thither the oxide of
zinc and other matters. This chamber should be divided into several
compartments and conveniently ventilated. The steam pipe is sunk in
the molten metal to such a depth that the steam may spread throughout
the mass of metal. If the boiler be very large and one jet of steam
insufficient to reach the zinc in every part the principal pipe may be
fitted with several auxiliary pipes, which will permit the steam to
penetrate quite through the molten lead; the higher the temperature.
of the steam the more prompt and efficacious will be its effect. It
will be prudent to adapt to the steam pipe externally two taps, one for
regulating the admission of steam into the metal, the other to first
opened to let off any water collected in the pipe, which will prevent any
spattering of the fused metal. I do not, however, restrict myself to the
exclusive use of taps; any other available means of regulating the
passage of steam and for drawing off the moisture and precluding
condensation may be employed. When the steam shall have been
introduced into the molten lead it will be desirable to ascertain when
the oxidation is completely terminated; to that end a valve, tap, or
other contrivance of the kind, with any suitable appliances, is fitted to
the escape tube to permit of seeing whether the steam passes in its
natural state clear of oxides or other matter, and then its function being
terminated the steam is suppressed. The cover with its appliances is
then removed, and all the oxides and other matter which float on the
surface are very lightly skimmed off, carefully avoiding the metal as

page_text: by which the lead is run off should be treated by an appliance in the
nature of a chafing dish or brazier or otherwise for the purpose of pre-
venting premature cooling. For conveyance of the moulds and in order
to expedite that operation I employ by preference, but not exclusively,
a railway or tramway with appliances for transmission which I call port
moulds or little trucks,
fill
When by the preceding operations several times repeated I have
obtained a sufficient quantity of argentiferous dross or rich litharge to
my second boiler I proceed then to treat it in the following manner :-
These rich skimmings or dross, composed principally of lead, silver, and
zinc, should be reduced to fusion with a view to oxidize and remove the
zinc and other matters as hercin-after described. When this is effected
the metal remaining may be refined by cupellation immediately
afterwards, inasmuch as it would contain considerably less lead than
after the usual Pattinson process, but it is preferable to treat it as next
herein-after explained. I light up the furnace under the second boiler
containing the rich litharge, and when the contents are in perfect fusion
I introduce a "mixer" without a box, but provided with radiating vanes
or paddles suspended and worked in the same manner as the "mixer"
first described or by any suitable arrangement, in order to amalgamate
the lead, silver, and zinc which compose the contents of the boiler.
I then extinguish or remove the fire, and I continue to skim as long
as possible all that coagulates on the surface, carefully casting into
the third boiler this new litharge, which I call "extra rich." If the
lead or rather the litharge or dross that remains in the second boiler,
still contain a certain quantity of silver I bring it again to a state of
fusion. I introduce this time a "mixer" having a perforated box
attached with a small quantity of zinc, in proportion to the requirement,
and I effect a complete mixture as herein-before described. Then I
draw the furnace and I again skim the coagulated surface, of which the
skimming is to be taken to the third boiler. If the metal, or rather the
litharge or dross that remains in the second boiler contain still a
quantity of silver nearly equal to that of the primitive silver lead, more
or less, it may be mixed with other metal prepared to undergo treatment
in the first boiler as herein-before described. In case, however, it is

page_text: As to.
much richer than the primitive silver lead, it is better to remelt it in
the second boiler and repeat the last preceding operation with a
"mixer" and box for the addition of the adequate proportion of zinc.
Often after the last operation the lead remaining in this second boiler
contains a very small and nearly insignificant portion of silver, so small
in fact that it may be disregarded. Then the contents of this boiler is
rehcated to fusion with a brisk fire, and the lead is purified by the aid
of one or more jets of steam cleared of oxide and skimmed, and the
remaining metal is subsequently poured or run into moulds.
the extra rich litharge or dross placed in the third boiler, when a
sufficient quantity is collected it is reduced to a perfect state of fusion,
and with the application of steam in a manner similar to that herein-
before described it is freed from the zinc and other matters of alloy or
impurity. Immediately after this operation the product may be taken
to the cupel furnace or otherwise disposed of for the purpose of
obtaining the silver in a state of purity by any approved method. In
order to complete the extraction of the silver so. as to obtain it in a
state of purity, or sufficiently pure for commercial utilization, the
operation herein-before described as applicable to the extra rich litharge
or dross is repeated in one or more melting pots, having by preference
somewhat the form of a crucible of which a range of three is by way
of illustration shown in the accompanying Drawings. To these melting
pots are adapted (with the modifications self-evident to a skilful
workman) the proper appliances for mixing, steaming, and separation,
regard being had to the process herein-before described. By those
means the zine which remains in affinity with the silver will be expelled,
and the comparatively small residue of lead and other alloys or
impurities that may remain in combination with the precious metal will
be dissipated, destroyed, or separated from it, thereby dispensing with
the usual process of cupellation or treatment by acid. When a
sufficient quantity of oxides and other matters of a nature to be converted
to useful purposes are collected suitable means are adapted to utilize-
the same.
Having thus set forth and particularly described and ascertained the
nature of the said Invention and in what manner the same is to be

page_text: A and B are two boilers shown in section, in which the operation
herein-before described as effected in the said first boiler is shown as
divided, the application of zinc taking place in the boiler marked A,
and the steaming and running into moulds in and from the boiler
marked B. 1 is the perforated box attached to a spindle with vanes
marked 2, turned by a crank handle marked 3. The cover for steaming
is marked 4. The steam pipe with the three branches and taps herein-
before mentioned are marked 5 and 6 respectively. 7 is the escape
pipe or conduit for the eduction of steam, and 7' shows an arrangement
of valve in the escape pipe for observing the progress and completion
of oxydation. C shows an arrangement of condensing chamber with
partitions or screens marked 8, having a ventilating tube marked 9.
H, E, F, show a range of small melting pots in the nature of
crucibles, as herein-before described, for the treatment of the products
ordinarily dealt with by cupellation or by acids for refining the silver,
in which designates a steam pipe with taps, and a "mixer."
A L, BL, CL, DL, HO, EO, FO, show the arrangement in plan
of an entire set of boilers and melting pots respectively constituting
the ranges herein-before described. G, an end view, shows a furnace
and door with a moveable grate marked with the Figure 11. M is a
mould of the ordinary kind into which the purified lead may be run
from the boiler B.
t
I do not, however, confine myself to the precise details of construction
and manipulation herein-before and in the said Drawings described,
the circumstances of my Invention requiring or admitting various
adaptations or modifications; but the essential bases of the said Invention
are set forth in the claims herein-after enumerated and specified.
Having now particularly described and ascertained the nature of the
said Invention, and in what manner the same is to be performed, I
declare that I claim,-
Firstly. The arrangement and combination of parts constituting the
treatment and apparatus herein-before described, which have not hereto-
fore to my knowledge been successfully and practically applied for the
purpose or purposes herein-before described.
Secondly. The application of the said apparatus or any modification
thereof for the separation of silver from argentiferous lead or for the
purification of lead.

page_text: Thirdly. The treatment of the silver product of the extra rich litharge.
or dross as herein-before mentioned in substitution partly or wholly for
refining by cupellation or by acid process.
In witness whereof, I, the said André Giraud, have. hereunto, seb
my hand and seal,, this Twenty-third day of April, in the
year of our Lord One thousand eight hundred and sixty-.
nine.
ANDRÉ GIRAUD. (L.S.),
Witness,
ROBERT MOORE.