Improvements in or relating to Processes for the Extraction of Gold and Silver from Ores.
Year: 1894

page_text: Date of Application, 4th Dec., 1894
Complete Specification Left, 18th Sept., 1895-Accepted, 9th Nov., 1895
PROVISIONAL SPECIFICATION.
Improvements in or relating to Processes for the Extraction of
Gold and Silver from Ores.
I, JOHANNES PFLEGER, of Kaiserslautern in the Empire of Germany, Chemical
Engineer, do hereby declare the nature of this invention to be as follows:-
The invention relates to the extraction of gold and silver by cyanide processes
from ores and metallurgical products.
The object of this invention is to obtain a more perfect precipitation of gold
and silver from cyanide solutions and at a lower cost than heretofore.
It may
be said to consist in employing a primary electric cell divided into compartments
by means of a porous partition or diaphragm having the cyanide solution of gold
or silver in
one compartment together with an electro negative substance
immersed in the solution, while in the other compartment is placed an electro
positive substance immersed in a solution capable of corroding that substance.
The electro-negative substance in the cyanide solution is connected with the
electro-positive in the other compartment by means of a conductor of electricity,
which is placed outside the solutions. An electric current is thereby generated
passing from the electro-negative substance through the conductor of electricity
placed outside the solutions to the electro-positive substance in the other com-
partment and thence through the solutions and porous partition to complete the
circuit. By this means the cyanide solution of gold and silver becomes decom-
posed and the gold and silver deposits upon the electro negative substance.
In carrying out the said invention I provide a vessel made of wood or other
non-conductor of electricity and 1 secure therein a porous partition of unglazed
earthenware or other suitable material, so that the solutions in the compartments
formed by the said partition do not mix. In one of these compartments is placed
an electro-positive substance such as zinc, iron, aluminium or the like and this
compartment is filled with a solution which will corrode the electro-positive
substance such as a metallic salt, an alkali or an acid. The other compartment
is filled with the cyanide solution from which it is desired to precipitate the gold
or silver, and an electro-negative substance that is a substance not readily acted on
by the cyanide solution such as carbon, lead gold silver or the like is immersed
in the cyanide solution. The electro-positive substance is connected with the
electro-negative substance by an electric conductor such as metal wire.
By this arrangement an electrolytic cell is formed of which the electro-positive
substance is the cathode and the electro-negative substance is the anode.
A current of electricity is thereby generated flowing from the anode through the
conductor to the cathode and thence through the solutions and porous partition
to complete the circuit. By this means the cyanide solution is decomposed and
the gold and silver are deposited upon the anode.
Dated this 4th day of December 1894.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to Processes for the Extraction of
Gold and Silver from Ores.
I, JOHANNES PFLEGER, of Kaiserslautern in the Empire of Germany, Chemical
Engineer, 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 :-
This invention relates to the extraction of gold and silver by cyanide processes
from ores and like substances.
The object of this invention is to obtain a more perfect precipitation or
deposition of gold and silver from cyanide solutions, in the before mentioned
processes, at a lower cost than heretofore.
It may be said to consist in employing a primary electric cell divided into
compartments by means of a porous partition, or diaphragm having the cyanide
solution of gold or silver, of a strength of 0, 3 parts or more of cyanide to
100 parts water, or gold and silver in one compartment together with an electro-
negative substance (the anode of the primary cell) immersed in this solution, while
in the other compartment is placed an electro-positive substance (the cathode)
immersed in a caustic soda solution of a strength of 1 to 5 parts caustic soda to
100 parts water capable of corroding that substance when in good electrical
connection with the electro-negative substance in the other compartment. An
electric current is thereby generated passing from the electro-negative substance
through the good conductor of electricity to the electro-positive substance in the
other compartment and thence through the solutions and porous diaphragm to
complete the circuit. By this means the cyanide solution of gold or silver becomes
decomposed, and the gold and silver deposits upon the electro negative substance.
By such an arrangement the electro-positive substance becomes the cathode and
the electro-negative substance the anode.
In the accompanying drawing I have shown an apparatus by which the said
invention may be conveniently and advantageously carried into practice.
Figure 1 is a vertical section of the said apparatus and
Figure 2 is a plan of the same.
A is a vessel preferably made of a non-conductor of electricity such as wood,
glass, carthenware or the like. 13 is a porous partition of unglazed earthenware,
or other suitable material, fixed into the vessel A so that the solutions in compart-
ments (and D) are kept separate as well as is practicable. In compartment C is
placed an electro-positive substance X such as iron, zinc copper aluminium or the
like while in compartment 1) is placed an electro-negative substance Y (that is a
substance not as readily acted on by the cyanide solution as the substance X is by
the same or a different solution). Such a substance may be gold, silver, carbon or
the like. X is connected with Y by an electric conductor E such as metal wire.
The compartment is filled with the cyanide solution from which it is desired to
precipitate the gold or silver, and compartment is filled with a solution which
will corrode the substance X while X and Y are in electrical connection, such as a
metallic salt, an alkali or an acid. By such an arrangement an electrolytic cell is
formed of which the electro-positive substance X is the cathode and the electro-
negative substance Y is the anode. A current of electricity is thereby generated
flowing from the anode Y through the conductor E to the cathode X and thence
through the solutions and porous partition to complete the circuit. By this
means the cathode dissolves and the gold and silver cyanide solution becomes
decomposed, whereby the gold and silver, or gold or silver are deposited upon the
anode Y in metallic form. The gold or silver thus obtained is in a more or less
impure state and can be separated from the anode and refined by any known
means.

page_text: It is found advantageous to cause the solutious, in both compartments, to be in a
state of motion during precipitation.
The drawing shows the cell in its simplest form, but a series of such cells may
be employed, whereby the solutions pass from one compartment to another, and the
operation may be either continuous or intermittent.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
I. The improvement in or relating to processes for the extraction of gold or
silver, or gold and silver from ores by means of a soluble cyanide which consists in
depositing or precipitating gold or silver from cyanide solutions in the manner
described.
II. The improvement in processes characterized in the first claim which consists
in employing the same substances electrically connected in different liquids of
which one liquid is a cyanide solution of gold or silver and separated from each
other by means of a porous partition, whereby the substance in the cyanide
solution is electro-negative to the substance in the other solution, substantially as,
and for the purpose described.
III. The improvement in processes characterized in the first claim which
consists in employing different substances, electrically connected, in different
liquids, of which one liquid is a cyanide solution of gold or silver, separated
from each other by means of a porous partition, whereby the substance in the
cyanide solution is electro-negative to the substance in the other solution,
substantially as, and for the purpose described.
IV. The improvement in processes characterized in the first claim which
consists in employing different substances, in cyanide solution of gold or silver
divided into compartments by means of porous partitions whereby the substance
in one compartment is electro-negative to the substance in the other compartment,
substantially as, and for the purpose described.
Dated this 18th day of September 1895.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.