Improvements relating to the Extraction of Lead and to Apparatus therefor.
Year: 1892

page_text: Date of Application, 5th Feb., 1892
Complete Specification Left, 5th Nov., 1892-Accepted, 17th Dec., 1892
PROVISIONAL SPECIFICATION.
Improvements relating to the Extraction of Lead and to Apparatus
therefor.
. Dr. BERNHARD RÖSING, of 149 Berlinerstrasse, Charlottenburg, and HANS
FOERSTER and KURT FOERSTER both of 128 Kurfürstendamm, Berlin, in the
Empire of Germany, do hereby declare the nature of this invention to be as
follows:-
Our invention relates to the extraction of lead by the aid of oxidic lead
compounds, and to apparatus therefor.
Use has heretofore frequently been made of lead sulphide for the extraction of
lead by means of oxidic lead compounds, which are either produced in the same
process from the ore at disposal by roasting and consist of sulphate or oxide, or
which have some other origin, such as litharge obtained in the cupellation, furnace
smoke, waste. In the reaction taking place the oxygen of the oxydic lead
compound is taken up by the sulphur of the lead sulphide with formation of
escaping sulphurous acid, while both the lead of the oxidic lead material and of
the lead sulphide are set free and obtained as metallic lead. If the oxidic lead
material contains lead sulphate the sulphur of the latter also precipitates in the
formation of the sulphurous acid. These phenomena occurring in the reaction may
be illustrated by the following equations:
2 PbO + PbS = 3 Pb + SO,
РbsО + PbS = 2 Pb +2 SO,.
This process as heretofore practised of extracting lead by heating a mixture of
lead oxide material and lead sulphide or appropriate lead ore, presents the
disadvantage that much time, working, power and fuel are needed, and that by
reason of the long time which the work takes an opportunity is afforded for an
ample volatilization of lead.
Moreover, the escaping sulphurous acid, which is very much contaminated with
smoke and thus rarified, can for this reason with difficulty be removed in an
efficient and economical manner.
To obviate these defects is the object of our invention which is to be attained on
the basis of these observations by causing the lead materials to act upon each other
in such a manner that the reaction will be speedily terminated and the sulphurous
acid evolved will remain as free from smoke as practicable.
Accordingly the oxidic lead material is brought together in such a state with
the lead sulphide material that the reaction will take place very rapidly and
without further artificial heating inasmuch as the heat generated in the reaction,
which occurs with great rapidity under these circumstances, will be quite sufficient
for keeping up the reaction itself. For this purpose the oxidic lead material may
according to our invention be advantageously brought, when already fused, in a
reverberatory furnace in contact with the lead sulphide material which is by
preference preliminarily heated, either the former material being caused to flow on
to the latter or the latter material being introduced into the fused oxidic lead
material. In this case sudden and violent mutual decomposition takes place which
is kept up by the heat generated in the reaction. There is therefore no necessity
for special heating during the reaction so that the sulphurous acid generated is
free from smoke and therefore concentrated as far as practicable and can readily
and profitably be utilized or removed..
Γ 1:L
haminhofove and hereinafter described with regard to lead

page_text: sulphide we may also allow carbon to act upon oxidic lead material, but then no
sulphurous acid but carbonic acid and carbonic oxide will be formed.
Our improved process can be advantageously carried into practice in a
reverberatory furnace which consists of two longitudinal chambers separated
from each other by a partition. This furnace is adapted to be turned in a
horizontal plane through an angle of 180 degrees upon a pivot which can be raised
a little by hydraulic means when it is arranged in an hydraulic cylinder, or by any
other suitable means, such as by screws. This turning movement may be effected
in any desired manner, for example we may arrange upon the under side of the
furnace a crown wheel with which engages a worm actuated by means of a crank.
The abutting faces of the flues and passages may suitably be bevelled for enabling
the furnace to turn upon its pivot and a tight joint to be formed when after the
turning movement the pivot has been lowered in the said hydraulic cylinder and
with it also the furnace.
One of the two chambers of the furnace is always in communication with the fire
place and through a flue with the chimney, while the other chamber is in com-
munication with a litharge aperture adapted to be closed by a cover for the molten
oxidic lead material, and by means of a flue with the discharge pipe for the
generated sulphurous acid.
With such an apparatus the above described process can be carried out in the
following manner, that is to say, one of the chambers is charged through its stoke
holes with the lead sulphide material to be used in as finely pulverized a state as
practicable, such as galena or lead sulphide obtained by reduction from lead
sulphate, and in this chamber which communicates with the fire place and with the
flue leading to the chimney the lead sulphide material is heated by means of the
said fire place until the galena will just commence to roast.
Then the furnace is
turned through an angle of 180 degrees so that the second chamber charged with
lead sulphide material through its stoke holes is set in communication with the fire
place.
Molten oxidic lead material of the kind hereinbefore characterized, preferably
molten litharge, is at the same time poured on to the hot lead sulphide material in
the first chamber through the litharge aperture. The mutual decomposition above
characterized takes place instantaneously with extremely rapid generation of heat.
Molten lead collects at the lowest point of the hearth where the discharge aperture
is provided, while sulphurous acid escapes through the flue into the passage for the
discharge of the same. This passage conducts the gas to the place where it is
utilized and where it may at will be collected in the form of sulphurous acid or
converted into sulphuric acid. When the decomposing action becomes weaker it
may be promoted by stirring. The separated lead is removed through the aforesaid
discharge aperture. The residues left after the termination of the work are with-
drawn through the orifice of the flue after the furnace has partly performed the
ensuing turning movement which 'becomes necessary in order to cause the reaction
of the charge of lead sulphide material, meanwhile preliminarily beated in the
second chamber, in the manner above described with reference to the first chamber..
The cooling of the preliminarily heated lead sulphide material caused by this short
delay has no deleterious effect, as the mutual decomposition generates an abundant
amount of heat.
The operations continually alternate in the manner set forth. While in one
chamber the lead sulphide material is preliminarily heated the mutual decomposition
takes place in the other chamber. Should the quantity of lead or silver contained
in the residues be great enough these residues may be treated in a shaft furnace for
the purpose of extracting these metals.
Dated this 5th day of Tshwu1.000

page_text: COMPLETE SPECIFICATION.
Improvements relating to the Extraction of Lead and to Apparatus
therefor.
We Dr. BERNHARD RÖSING of 149 Berlinerstrasse, Charlottenburg and
HANS FOERSTER and KURT FOERSTER both Minors, of 128 Kurfürstendamm,
Berlin, in the Empire of Germany, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement :-
Our invention relates to the extraction of lead by the aid of oxidic lead com-
pounds, and to apparatus therefor.
Heretofore use has frequently been made of lead sulphide for the extraction of
lead by means of oxidic lead compounds, which are either produced in the same
process from the ore at disposal by roasting and consist of sulphate or oxide or
which have some other origin, such as litharge obtained in the cupellation, furnace
smoke, waste or the like. In the reaction taking place the oxygen of the oxidic
lead compound is taken up by the sulphur of the lead sulphide, with the formation
of escaping sulphurous acid, while both the lead of the oxidic lead material and of
the lead sulphide are set free and obtained as metallic lead. If the oxidic lead
material contains lead sulphate the sulphur of the latter also participates in the
formation of the sulphurous acid.
These phenomena occurring in the
reaction may be illustrated by the following
This process as heretofore practised of extracting lead by heating a mixture of
lead oxide material and lead sulphide or appropriate lead ore presents the
disadvantage that much time, working power and fuel are needed, and that by
reason of the long time which the work takes an opportunity is afforded for an
ample volatilization of lead.
Moreover the escaping sulphurous acid, which is very much contaminated with
smoke and thus rarefied, can only for this reason be removed in an efficient and
economical manner with considerable difficulty.
To obviate these defects is the object of our invention, which is to be attained
on the basis of these observations by causing the lead materials to act upon each
other in such a manner that the reaction will be speedily terminated and the
sulphurous acid evolved will remain as free from smoke as practicable.
Accordingly the oxidic lead material is brought together in such a state with
the lead sulphide material that the reaction will take place very rapidly and
without further artificial heating, inasmuch as the heat generated in the reaction
which occurs with great rapidity under these circumstances, will be quite sufficient
for keeping up the reaction itself. For this purpose the oxidic lead material may,
according to our invention, be advantageously brought, when already fused in a
reverberatory furnace in contact with the lead sulphide material which is by
preference preliminarily heated, either the former material being caused to flow on
to the latter, or the latter material being introduced into the fused oxidic lead
material. In this case a sudden and violent mutual decomposition takes place
which is kept up by the heat generated in the reaction. There is therefore no
necessity for special heating during the reaction, so that the sulphurous acid
generated is free from smoke and therefore concentrated as far as practicable and
can readily and profitably be utilized or removed.
In like manner as hereinbefore and hereinafter described with regard to lead

page_text: sulphide we may also allow carbon to act upon oxidic lead material, but then no
sulphurous acid but carbonic acid and carbonic oxide will be formed.
In the accompanying drawing we have shown how our improved process can be
conveniently and advantageously carried into practice in a reverberatory furnace.
Figure 1 is a vertical longitudinal section through one of the chambers of the
furnace.
Figure 2 is a similar view through the other chamber of the said furnace.
Figure 3 is a horizontal section of the same and
Figure 4 is a transverse section thereof.
The said furnace consists of two longitudinal chambers H and K separated from
each other by a partition W. This furnace is adapted to be turned in a horizontal
plane through an angle of 180 degrees upon a pivot Z which can be raised a little
by hydraulic means for which purpose it is arranged in an hydraulic cylinder O
or the said furnace can be raised by any other suitable means such as by screws.
This turning movement may be effected in any desired manner for example, we
may arrange upon the underside of the furnace a crown wheel L with which
engages a worm M actuated by means of a crank. The abutting faces P and P¹
of the flues and passages may be suitably bevelled for enabling the furnace to turn
upon its pivot Z and a tight joint to be formed when, after the turning movement,
the pivot Z has been lowered in the said hydraulic cylinder O and with it also the
furnace.
One of the two chambers K or H of the furnace is always in communication
with the fire-place F and through a flue E with the chimney, while the other
chamber is in communication with a litharge aperture G adapted to be closed by a
cover, for the molten oxidic lead material and by means of a flue S with the
discharge pipe for the generated sulphurous acid.
With such an apparatus the above described process can be carried out in the
following manner, that is to say, one of the chambers K is charged through its
stoke holes T with the lead sulphide material to be used, in as finely pulverized a
state as practicable, such as galena or lead sulphide obtained by reduction from
lead sulphate, and in this chamber, which communicates with the fire place F and
with the flue E leading to the chimney, the lead sulphide material is heated by
meaus of the said fire place until the galena commences to roast.
The furnace is then turned through an angle of 180 degrees so that the second
chamber H charged with lead sulphide material through its stoke holes T is set in
communication with the fireplace. Molten oxidic lead material of the kind herein-
before characterized, preferably molten litharge is at the same time poured on to
the hot lead sulphide material in the first chamber K through the litharge
aperture G. The mutual decomposition above characterized takes place instan-
taneously with extremely rapid generation of heat. Molten lead collects at the
lowest point of the hearth where the discharge aperture a is provided, while
sulphurous acid escapes through the flue S into the passage for the discharge of
the same.
This passage conducts the gas to the place where it is utilized and where it may
at will, be collected in the form of sulphurous acid or converted into sulphuric acid.
When the decomposing action becomes weaker it may be promoted by stirring.
The separated lead is removed through the aforesaid discharge aperture a.
The residues left after the termination of the work are withdrawn through the
orifice of the flue after the furnace has partly performed the ensuing turning move-
ment which becomes necessary in order to cause the reaction of the charge of lead
sulphide material, meanwhile preliminarily heated in the second chamber H, in the
manner above described with reference to the first chamber K. The cooling of
the preliminarily heated lead sulphide material caused by this short delay has no
deleterious effect, as the mutual decomposition generates an abundant amount
of heat.
The operations continually alternate in the manner set forth. While in one
chamber the lead sulphide material is preliminarily heated the mutual decomposition

page_text: takes place in the other chamber. Should the quantity of lead or silver contained
in the residues be great enough these residues may be treated in a shaft furnace for
the purpose of extracting these metals.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed we declare that what we
claim is :-
First. The hereindescribed process of extracting lead by the aid of lead oxide
material, which consists in bringing the same together in the fused state with the
decomposing material, which may be preliminarily heated if desired, such as lead
sulphide material or its described substitute, whereupon the separation of lead takes
place without further special external heating.
Second. An apparatus adapted for carrying out the process set forth in the first
claim, which consists of a reverberatory furnace arranged to turn upon a vertical
axis (Z), and divided by a longitudinal partition (W) into two completely separate
chambers (H, K), of which one serves alternately for preliminarily heating the lead
sulphide material or its substitute and is in this case put in communication with the
furnace (F), whilst in the other chamber the decomposition of fused lead oxide
material admitted in the meantime takes place by means of the preliminarily heated
lead sulphide material or its substitute.
Dated this 1st day of November 1892.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, Agents for the Applicants.