IMPROVEMENTS IN TREATING LEAD ORES
Year: 1868

page_text: LETTERS PATENT to Paul Emile de Wissocq, residing at No. 11, Rue
Richepanse, Paris, in the Empire of France, for the Invention of
"IMPROVEMENTS IN TREATING LEAD ORES."
PROVISIONAL SPECIFICATION left by the said Paul Emile de Wissocq
at the Office of the Commissioners of Patents, with his Petition,
on the 9th November 1868.
I, PAUL EMILE DE WISSOCQ, residing at No. 11, Rue Richepanse,
Paris, in the Empire of France, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN TREATING LEAD OBES," to be as follows:-
This Invention consists, first, in converting lead ores into chloride by
treating them with hydrochloric acid.
Second. In dissolving the chloride of lead in boiling water and in
putting the solution into contact with wrought or cast iron in the form
of bars which decompose it, precipitating the lead in the metallic state
and forming chloride of iron, which remains in the solution in place of
the chloride of lead.

page_text: Third. In collecting the precipitated lead and melting it in a furnace
or in a pot and casting it into pigs.
Fourth. When the mineral contains silver, in treating with a boiling
and concentrated solution of salt the residue which is left after all the
chloride of lead has been dissolved. The solution of salt dissolves the
chloride of silver, leaving the other matters undissolved, and by the
addition of metallic copper the silver is precipitated.
Fifth. In collecting for use the secondary products, which are sul-
phuretted hydrogen and chloride of iron.
These operations are, separately, well understood, but they have never
been combined for the practical extraction of lead from minerals con-
taining it.
In conducting these operations the following apparatus is employed:-
First, a furnace over which is placed a series of boilers heated either
directly by the fire or better through a water bath. These boilers are
connected with suitable pipes for filling them, for drawing off the con-
tents, and for the escape of the sulphuretted hydrogen which is formed.
The covers of the boilers should fit gas-tight, and through each an axis
passes, giving motion to agitators within the boiler; there is also a pipe
for running in acid. The pipe through which the sulphuretted hydrogen
escapes leads to a vessel in which the gas is washed. Second, another
furnace is employed, and over it is placed a boiler in which is put water
and chloride of lead. At the upper part of this boiler is an upward-flow
filter through which the solution of chloride of lead passes and filters
before entering a large wooden vat in which are placed wooden cages
containing bars of cast or wrought iron for the precipitation of the lead.
The chloride of lead is decomposed, the metal being deposited upon the
bars, and an elevator placed at the end of the vat takes off the water
from which the lead has been separated and takes it into a reservoir,
from which it returns whilst still hot into the boiler, where it is charged
again with chloride of lead. From time to time the cages containing
the iron bars are taken out and the lead is cleaned off them. When the
sulphuretted bydrogen cannot be used directly it is converted into sulphur
in a large chamber or receiver, into which it is led by two different
openings, by one of these two-thirds of the sulphuretted hydrogen pro-
duced enters, and by the other the remaining third after it has been
burnt so as to transform it into sulphurous acid. A jet of steam facili-
tates the action of the acid gas upon the sulphuretted hydrogen, a

page_text: reaction which produces steam and sulphur, which is deposited in a fine
powder.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Paul Emile de Wissocq in the Great Seal Patent
Office on the 8th May 1869.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PAUL
EMILE DE WISsocQ, residing at No. 11, Rue Richepanse, Paris, in the
Empire of France, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Ninth day of November, 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 me, the said Paul Emile de Wissocq, Her special
licence that I, the said Paul Emile de Wissocq, my executors, adminis-
trators, and assigns, or such others as I, the said Paul Emile de
Wissocq,. 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 TREATING LEAD ORES," upon the condition (amongst others) that
I, the said Paul Emile de Wissocq, my executors. or administrators, by
an instrument in writing under my, or their, or oue 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 Paul Emile de Wissocq, 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,. that is to say :-
The process consists, first, in converting lead ores into chloride by
treating them with hydrochloric acid.

page_text: Second. In dissolving the chloride in water and allowing it to remain
in contact with wrought or cast iron, or, better still, upon iron sponge,
which decomposes it, precipitating the lead in a metallic state and
forming chloride of iron, which remains in solution in place of the
chloride of lead.
Third. In collecting the precipitated lead and melting it in a furnace
or in a pot and then casting it into pigs.
Fourth. In collecting the two secondary products which are formed,
and which are sulphuretted hydrogen and chloride of iron.
Fifth. When the mineral contains silver, in treating with a boiling
and concentrated solution of salt the insoluble residue which is left after
all the chloride of lead has been dissolved.
Sixth. Precipitating by copper the chloride of silver dissolved in the
preceding operation.
Seventh. Employing either hyposulphite of soda or any other body
having the property of dissolving chloride of silver in place of sea salt
for dissolving the chloride of silver.
These operations are separately well understood, but they have never
been combined for the practical extraction of lead from minerals con-
taining it.
The apparatus which I prefer to employ consists, first, of a furnace to
heat directly or by a water bath a series of boilers furnished with pipes
for drawing off the contents, and for the escape of sulphuretted hydrogen
which is given off. Each of the boilers is fitted with a cover through
which passes an axis giving motion to an agitator; within the boiler
there is also a tube for the introduction of the ores. A tube placed at
the side of each boiler can be conveniently employed for introducing
acid, and this tube may also serve in case of need as a safety tube. I
connect the tube through which the sulphuretted hydrogen escapes to a
a tube which conducts the gas to a vessel in which the gas is washed.
The arrangement which I prefer is indicated at Figures 1 and 2.
The boilers are placed in a large tank of wood, through the bottom of
which is led the tube by which the products which remain in the boiler
after each operation are drawn off. This tank is filled with oil or with
the saline solution which is to be the heating medium, and it is put in 3
communication by two horizontal tubes at different levels with another
boiler heated by a furnace. By this arrangement as the liquid contained

page_text: in the tank becomes heavier in cooling it returns by the lower tube to
be reheated in the boiler, whilst hotter liquid flows through the upper
tube, and thus a current is established by which a constant temperature
is maintained in the tank little inferior to that in the boiler.
Secondly. Figures 3 and 4, of a wooden tank, in the top of which is
an up-flow filter, and of a second tank or large wooden vat divided into
compartments, in which are placed large cages of wood containing bars of
malleable or pig iron for precipitating or depositing the chloride of lead.
When in place of conducting the process at ordinary temperature it is
preferred to employ heat to shorten the process (the chloride being
much more soluble and depositing much for quickly when hot than
when cold) I employ a boiler in place of the first tank. An elevating
apparatus placed at the end of the vat serves to carry off the water
which has been deprived of its chloride of lead, and to return it to the
first tank, in which is placed the mixture of gangues and chloride of
lead withdrawn from the boilers of chloridization, or into the boiler
which replaces this tank when heat is employed. When spongy iron is
employed for the depositing process the depositing goes on with great
rapidity, and the wooden vat may be arranged as shown in Figures 5
and 6; each of the compartments may in this arrangement become
in succession either the first, second, or last, so that the last may
contain fresh spongy iron which takes from the water the last traces of
chloride before it is carried back to the dissolving tank, and so that
the more concentrated solution of chloride of lead comes into the
compartment which contains the sponge already nearly converted into
lead.
Thirdly. Figure 7, of a chamber where sulphuretted hydrogen is
changed into water and sulphur.
Mode of Conducting the Operation.-The ore is pulverised as fine as
possible; it is then placed in one of the boilers, Figures 1 and 2, and
warmed by the fluid bath to about 100% centigrade; it is then treated
with hydrochloric acid; the reaction is instantaneous. Chloride of lead
is formed and sulphuretted hydrogen is given off, which carries away
with it vapors of hydrochloric acid. These vapours are absorbed by
the water in the washing bath, and the sulphuretted hydrogen passes in
a pure state into the chamber, where it is changed into sulphur. After
about 5 or 6 hours the action of the acid upon the ore is completed.
The tube situated at the bottom of the boiler is then opened and the

page_text: contents of the boiler are drawn into a trough and allowed to settle;
the fluid is then run off, and then I pour a little cold water on to the
solid residue to wash it, and then pour off again. There remains at the
bottom of the trough a mixture of chloride of lead (which being almost
insoluble when cold remains there almost entirely) and of chloride of
silver if the ore contains that metal, and also the gangue of the ore..
I then carry the residue into the vat or into the boiler, Figures 3 and 4,
which I fill with water to a sufficient height. This water when saturated
with chloride of lead and having passed through the filter drains off by
the opening made for it through the case of the filter, and goes into the
precipitating or depositing vat. This water in traversing the different
compartments of the vat loses little by little its chloride of lead, which
is changed into chloride of iron, and it arrives at the end of the vat
deprived of the chloride of lead, where it is raised by an elevating
apparatus to a sufficient height to allow it to flow back by a suitable
pipe to the dissolving tank, where it is charged afresh with chloride of
lead, so that the same water is in continual circulation and becomes
more and more charged with chloride of iron, and so only requires a
small quantity of fuel to keep it hot when it is desired to carry on the
process with heat. The water is not changed until it is nearly saturated
with chloride of iron. From time to time when the bars of iron are
sufficiently covered with lead I lift out the cages above mentioned by
means of a winch, and clean them whilst out of the vat. The lead
obtained is washed, then dried and melted in a furnace or pot and run
into pigs; it is completely pure. When instead of iron I use spongy
iron for the depositing process I begin by closing the opening which
connects the compartment which is to be the first with its neighbour
which is to be the last, Figures 5 and 6. The outlet from this latter is
also opened to allow the water deprived of its chloride of lead to escape
in order that it may be carried back by the elevating apparatus into the
dissolving tank, whilst the water passing from this tank and which is
charged with chloride of lead is caused to enter into the first com-
partment in a constant stream until all the spongy iron in this
compartment is changed into lead; I then withdraw it to melt it and
place fresh sponge in the compartment, which should now in place of
being the first be the last; while that which was second becomes first,
and that which was third becomes second, and thus the operation goes
on continuously. When all the chloride of lead which has been placed
with the gangues in the dissolving tanks is exhausted I draw out the

page_text: residue, which I treat, as before stated, with a boiling and concentrated
solution of sea salt, or of hyposulphite of soda to dissolve the chloride of
silver, and to extract the silver by deposition with copper, a process
which is well known. When chloride of iron is present it can be
crystallized by evaporation and collected. As to the sulphuretted
hydrogen it is changed into sulphur in the apparatus shewn at Figure 7,
which is a large chamber, into which is introduced a mixture in proper
proportions of sulphurous acid and sulphuretted hydrogen, which are
mixed by jets of steam, and which acting one on the other produce
water and sulphur, which is deposited at the bottom of the chamber.
To obtain a mixture in proper proportions of the two gases they are
caused to enter separately into the chamber by two pipes, the openings
from which are so proportioned that one, viz., the one for sulphuretted
hydrogen shall pay double the quantity of the other; the gas passed
through the latter is lighted, and the sulphurous acid produced is
precisely the proportion necessary to decompose the two volumes of
sulphuretted hydrogen passed through the first tube.
In witness whereof, I, the said Paul Emile de Wissocq, have here-
unto set my hand and seal, this Sixth day of May, in the year of
our Lord One thousand eight hundred and sixty-nine.