IMPROVEMENTS IN DESILVERING LEAD OR SEPARATING SILVER THEREFROM, AND IN APPARATUS FOR THE PURPOSE
Year: 1871

page_text: LETTERS PATENT to Michael Henry, of Fleet Chambers, 68, Fleet
Street, in the City of London, Patent Agent, for the Invention of
“IMPROVEMENTS IN DESILVERING LEAD OR SEPARATING SILVER THEREFROM,
AND IN APPARATUS FOR THE PURPOSE."-A communication from abroad
by Charles Just Felix Raoul de Jaunel de Vauréal, of 17, Boulevart
Saint Martin, Paris, France.
PROVISIONAL SPECIFICATION left by the said Michael Henry at the
Office of the Commissioners of Patents, with his Petition, on the
13th September 1871.
I, MICHAEL HENRY, of Fleet Chambers, 68, Fleet Street, in the City
of London, Patent Agent, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN DESILVERING LEAD OR SEPARATING SILVER
THEREFROM, AND IN APPARATUS FOR THE PURPOSE," communicated to me from

page_text: abroad by Charles Just Felix Raoul de Jaunel de Vauréal, of 17,
Boulevart Saint Martin, Paris, France, to be as follows:-
This Invention has for its object a method of and apparatus for
desilvering lead or separating silver therefrom by zincing or by the use.
of zinc. The lead acted on is pig lead, raw, or workable lead. The
process is based on the fact that a ratio exists between chemical action
and the extent of surface acted on. Hence by multiplying the surfaces
of metal to be purified by oxidation the process can be expedited. When
the zinc process is used and a ternary or triple alloy is formed (lead,
zinc, and silver) the separation results from two properties of the alloy,
first, its density is less than that of lead; second, the separation by
crystallization is effected at a temperature above the melting point of
the lead. By applying these properties to desilvering lead according to
this improved process; that is to say, by a series of three crystallizations
of the ternary alloy (assisted by the fact of its density being less than
that of lead), the desilvering or separation of the silver is effected.
In order to render the process exact and regular a signal, alarm or
tell-tale is employed to indicate by sound the completion of each stage
of the process, and it is worked by electricity or electro-magnetism.
This apparatus is a manometer or air pressure gauge acting as a
thermometer, that is to say, it indicates the expansion of air due to the
varying temperature generated. The air is in a barrel or cylinder
communicating with this thermo-manometer. Apparatus herein-after
described is used with advantage for performing the process.
In order that the Invention may be fully understood I describe
particularly the mode in which it may be performed.
First. The lead is submitted to eliquation in a boiler or cauldron
(heated by a furnace), and it is then superheated (to dull red heat). The
electric signal indicates the termination of this stage of heating. The
superheated lead then passes into à chamber furnished with a perforated
bottom, through which it is showered into a lower chamber, and it is
there brought in contact with superheated air. The metal and slag or
dross fall to the bottom, and the vapours or aeriform products pass into
condensation chambers. Decantation takes place in the lead chamber,
and the lead flows into a receiver furnished with a syphon, which at
intervals discharges the metal into moulds, which shape it for trans-
ference into the boilers or cauldrons. A perforated pan mounted at the

page_text: end of a rod and charged with zinc is inserted at the required intervals
into the receiver.
Secondly. The next boiler or cauldron is heated by a travelling
furnace, and heated air is projected from the stationary furnace which
heats the first named boiler or cauldron. When the fusion is effected
and indicated by the thermo-manometer, zinc is injected and valves are
worked to inject heat from the furnaces into another boiler or cauldron,
in which a similar operation proceeds. The zinciferous dross rises, is
crystallized, and again melted and zinced.
Thirdly. When the metal has been subjected to eliquation and zinced,
and twice skimmed, the syphon is opened. This syphon is screwed to a
neck on the boiler shell, a brass being between the screw threads, and
the syphon is closed by a screw plug made tight by a platina ring
coated with chloride of zinc. Thus the air intercepted in the syphon is
held therein during the process. The syphon allows the metal to decant
from the cauldron or boiler, but does not empty it completely. It leaves
a residuum at bottom in which are left the sparse crystals of the alloys
which have not become incorporated with the dross. The lead flows
into the first-named boiler or cauldron, where it is superheated and
refined in a separate chamber with condensation chambers, so as to
separate the products.
The zinciferous dross is subjected to eliquation in other cauldrons or
boilers to be enriched. The argentiferous lead separated from it passes
into the second and third named boilers or cauldrons.
The enriched zinciferous slag or dross is melted in another boiler and
chloruretted with chloride of lead expedited by a plunger containing
green timber and carrying bent tubes with rose tops. Under the
pressure
of the gases produced by the distillation of the timber the lead bubbles
up to the top of the bath, and passes in a state of globule to the
chloruretting layer.
The rich litharge can be used for the manufacture of chloride of lead,
so as to release the silver therein contained. To this chloruretted
litharge may be added the impure litharge resulting from the process of
amelioration and purified by the chloruretting process, so that extraneous
metals are expelled.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Michael Henry in the Great Seal Patent Office on
the 13th March 1872.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, MICHAEL
HENRY, of Fleet Chambers, 68, Fleet Street, in the City of London,
Patent Agent, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirteenth day of September, in the
year of our Lord One thousand eight hundred and seventy-one, in the
thirty-fifth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Michael Henry, Her special licence that
I, the said Michael Henry, my executors, administrators, and assigns, or
such others as I, the said Michael Henry, 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 DESILVERING LEAD OR SEPARATING
SILVER THEREFROM, AND IN APPARATUS FOR THE PURPOSE," communicated to me
from abroad by Charles Just Felix Raoul de Jaunel de Vaureal, of 17,
Boulevart Saint Martin, Paris, France, upon the condition (amongst
others) that I, the said Michael Henry, my executors or adminis-
trators, 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 Michael Henry, do hereby declare the
nature of the said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement thereof, as communicated to me, reference being
had to the accompanying Drawings, and to the letters and figures marked
thereon, that is to say :-
This Invention has for its object a method of and apparatus for
désilvering lead or senarating silver therefrom hy zincino or he the usa

page_text: of zinc. The lead acted on is pig lead, raw or workable lead. The
process in so far as regards the amelioration and dezincing is based on
the fact that a ratio exists between chemical action and the extent of
surface acted on. Hence by multiplying the surfaces of the metal to be
purified by oxidation the process can be expedited. When the zinc
process is used (which though investigated in 1842 by Kersten and by
Parkes and Cordurier, was not carried to the present point), a ternary or
triple alloy is formed consisting of lead, zinc, and silver. The separation
results continuously, owing to two properties of the alloy, first, the
density thereof is less than that of lead; second, the separation by
crystallization is effected at a temperature above the melting point of
the lead. By applying these properties to desilvering lead according to
this improved process, that is to say, by a series of three crystallizations
of the ternary alloy (assisted by the fact of its density being less than
that of lead) the desilvering or separation of silver is rapidly and
completely effected.
In order to render the process exact and regular a signal alarm or
tell-tale is employed to indicate by sound the completion of each stage
of the process of desilvering, and it is worked by electricity or electro-
magnetism. This apparatus is a manometer or air pressure gauge, acting
as a thermometer, that is to say, it indicates the expansion of air due to
the varying temperature generated. The air is in a barrel or cylinder
communicating with this thermo-manometer. The apparatus herein-
after described is used for performing the process.
In order that the Invention may be fully understood,' I proceed to
describe particularly the mode in which it may be performed, with
reference to the accompanying Drawings, which represent apparatus
constructed according to the Invention.
Figure 1 is a vertical sectional elevation of apparatus constructed
according to and for carrying out this Invention, so that the process
herein-before described may be performed; Figure 2 is a sectional
elevation of part of the apparatus; Figure 3, a plan.
First Operation.-Amelioration of the Workable Lead.-This operation
is described for lead containing iron, tin, bismuth, antimony, and other
matters. First the lead is submitted to eliquation in a covered or close
boiler or cauldron A heated by a furnace F. This furnace is preferably
so constructed as to be capable of melting or fusing 15 tons lead in

page_text: 4 hours. The fused lead is superheated to a dull red heat. The clectric
or thermo-manometric bell signal T, herein-after described, indicates the
termination of this stage of heating. The superheated lead in the
cauldron or boiler A then passes through a communicating pipe m into
a receiver D'. This receiver is a chamber furnished with a bottom n,
perforated or pierced with capillary orifices or openings through which
the molten lead is showered in fine showers into a lower chamber K,
which is situated immediately under the receiver D¹, and in that
chamber K. the lead is brought in contact with a current of superheated
air which is furnished thereto by pipes H, I, the supply being regulated
by tap G. The metal and slag or dross fall to the rounded bottom J of
the chamber K. The fumes or vaporous or aeriform products are
conveyed through a passage O, and pass into and condense in con-
densation chambers Q, Q. Decantation takes place spontaneously in
the bottom J of the lead chamber K, and the lead flows through a
passage p into a receiver E furnished with a syphon q, which at intervals
discharges the metal into a series of moulds 1, 1, 1, 1, shewn in plan
Figure 3, which shape it into a round or disc form for transference into
the boilers or cauldrons B, B', Figure 2. A perforated pan at the end
of a long rod and charged with zinc is inserted at required intervals into
the receiver. If the capacity of the receiver E corresponds with a ton
of lead the pan should contain 2 lbs. 3 oz. of zinc. The zinciferous
slag or dross which floats at the surface of the receiver E may when
collected or skimmed off be treated apart by a separate treatment if the
metal contains gold.
Second Operation.-Desilvering.-The boilers or cauldrons B and B
are fed with ameliorated working lead, already submitted to a
preliminary zincing operation as above described, and which is then
subjected to an alternative fusing operation.
For this purpose a
moveable or travelling furnace W is used. This travelling furnace heats
the boiler or cauldron B, and by arranging the valves S, S', S", so that
they may work alternately the heat derived from the furnace F is added
to that of the moveable furnace W. When the fusion of the metal is
effected and the thermometric apparatus announces that the desired
point has been attained, say 365° centigrade or 689° Fahrenheit, the
half of the zinc to be employed is carried to the bottom of the receiver by
means of a strong vessel or pan manipulated by a long rod not shewn in
the Drawing, but resting or centered on the blocks R, R. After the

page_text: operation has been performed in the receiver B, a like operation is
performed in the receiver B¹. When this apparatus is worked the valves
S, S¹, S¹¹, also work so as to actuate the furnace valves in such manner
as to carry out the above-described process, that is to say, to inject heat
from the furnaces W, F, into one or other of the cauldrons B, B¹, the
one in which the fusing process is to be carried on. The products are
skimmed so as to remove the scum or dross containing zinc. The
cauldron is set to work again, the products crystallized, re-melted, and
treated with zinc the second time. In both cauldrons the skimming is
effected at a temperature of 335° centigrade or 635° Fahrenheit, which
is indicated by the electric alarm; it sounds when the heat is at
345° centigrade or 653° Fahrenheit, and continues till it descends to
335° centigrade, say 635° Fahrenheit. While it sounds a workman
separates the slag or dross with a pick, and when it sounds a second
time he skims and places the slag or dross in the receivers C, C¹.
1
16
Third Operation.-When the metal has been subjected to eliquation in
the first cauldron B, zinced, and twice skimmed, the syphon of this
cauldron is opened by a workman standing on a platform. This syphon
is screwed to a neck on the boiler or cauldron shell cast in a piece
therewith; a brass is between the screw threads. The syphon does not
allow the lead to trickle in threads or slender streams; for this purpose
the end of the syphon is closed by a screw plug made tight by a
platina ring coated with chloride of zinc. Thus the air intercepted in
the syphon is held therein during the process. The syphon allows the
metal to decant from the cauldron or boiler, but does not empty it
completely. It leaves a residuum, say about of the lead, at
bottom in which are left the sparse crystals of the alloy, (lead, zinc, and
silver), which by their density float at the upper part of the fluid metal
and have not become incorporated with the liquid metal. The receivers
B, B', are best of such dimensions as to hold 16 tons, say 15 to be
worked, and one to be left at the bottom of the receiver. The lead
containing zinc and entirely desilvered flows into the first-named boiler
A, where it is at once superheated as in the first operation, but it is
refined in a separate chamber or riddle D passing through a corre-
sponding chamber and having special condensation chambers, and thus
make a distinction between the fumes or vapours of the ameliorating
process and those of the process of refining the zinc containing lead.
The lead purified and deprived of zinc is conveyed into a receiver M,

page_text: whence it is ladled out in order to be moulded or stamped with a
trade mark. This receiver M. should have a spout, so that the lead may
not be ladled out when too hot.
Fourth Operation.-The zinciferous dross is subjected to eliquation in
the cauldrons or boilers C, C', in order to be enriched. The argentiferous
lead separated from it passes into the second and third named boilers or
cauldrons B, B¹.
Fifth Operation.-The enriched zinciferous slag or dross is melted in a
boiler Y, Figure 4, and chloruretted with chloride of lead. The process
is expedited by using a wrought-iron plunger a containing logs of green
timber 6, and carrying at the sides bent iron tubes c, c, with rose tops,
which are at the level of the bath of chloride of lead and zinc; under
the pressure of the gases produced by the distillation of the timber the
lead bubbles up to the top of the bath, and passes in a state of globule
through the chloruretting layer.
The rich litharge from the rich lead which is ladled or skimmed can
be used for the manufacture of chloride of lead, so as to release the
silver therein contained. To this rich chloruretted litharge may be
added the impure litharge resulting from the process of amelioration
and purified by the chloruretting process, so that extraneous metals are
separated.
The fumes, vaporous or aeriform products of the desilvered lead may
be utilized as zinc white, or treated with slag or dross for re-obtaining
zinc and lead. The residue of the chloruretting operation may be
treated with lime when hydrate of oxide of zinc and oxide of lead will
be produced.
The electro-magnetic alarm will be worked by the contact of a needle
such as is used in Bourdon's gauge on a copper stud. It is in effect a
manometer serving as a. thermometer, that is to say, it marks the
expansion of air produced by the temperature in the cauldron. The
air is contained in a barrel or tube communicating with the gauge.
When this is once regulated the apparatus will work regularly.
Having now described the nature of the said Invention, and in what
manner the same may be performed, I declare that I claim,—
First. The process of desilvering lead by a series of operations as
herein-before described.

page_text: Second. The use and construction of the apparatus in which the
process is performed, the said apparatus having its parts arranged and
combined substantially as set forth.
In witness whereof, I, the said Michael Henry, have hereunto set
hand and seal, this Thirteenth day of March, in the year
One thousand eight hundred and seventy-two.
my
Witness,
E. DE PASS,
68, Fleet Street,
London.
M. HENRY. (L.S.)