IMPROVEMENTS RELATING TO THE EXTRACTION OF GOLD, SILVER, AND OTHER METALS FROM ORES AND OTHER SUBSTANCES, AND IN APPARATUS THEREFOR, WHICH APPARATUS IS APPLICABLE FOR OTHER PURPOSES
Year: 1876

page_text: LETTERS PATENT to Richard Werdermann, of Princes Street, in the County
of Surrey, Civil Engineer, for the Invention of "IMPROVEMENTS RELATING TO
THE EXTRACTION OF GOLD, SILVER, AND OTHER METALS FROM ORES AND OTHER
SUBSTANCES, AND IN APPARATUS THEREFOR, WHICH APPARATUS IS APPLICABLE
FOR OTHER PURPOSES."
Scaled the 30th September 1876, and dated the 5th April 1870.
PROVISIONAL SPECIFICATION left by the said Richard Werdermann at the
Office of the Commissioners of Patents on the 5th April 1876.
RICHARD WERDERMANN, of Princes Street, in the County of Surrey, Civil
Engineer. "IMPROVEMENTS RELATING TO THE EXTRACTION OF GOLD, SILVER, AND
OTHER METALS FROM ORES AND OTHER SUBSTANCES, AND IN APPARATUS THEREFOR,
WHICH APPARATUS IS APPLLICABLE FOR OTHER PURPOSES."
My Invention relates to improved methods of and apparatus for the extraction of
gold, silver, and other metals from their ores, tailings, and other substances.
The extraction of gold and silver from ores in which the precious metals are
contained in a free state does not present any difliculty, but a great part of gold
ores, silver ores, and auriferous silver ores, principally those which contain arsenic
and antimony, or complex arseniuretted and antimonuretted combinations of metals,
resist all hitherto known methods of treatment, and give up only a portion of the
precious metals..
The various ores are so different in character that it would not be advantageous
to treat all of them in the same manner, and therefore it is necessary to first
ascertain by analysis of the ore which method or process is best suited for the
extraction of the precious metals from the same. This is especially necessary with
regard to silver ores.
My improved process of treating these ores, especially sulphurets and other
refractory ores, is as follows, that is to say:-I first convert the sulphurets into
sulphates by means of ozone or into oxides by means of oxygen or ozone, after
elimination of the sulphur and arsenic, or part of them by hydrogen. The sulphates
are lixiviated, and the sulphate of silver is extracted from the lye by crystallization
produced by cold, or the silver is extracted by electro deposition or reduced by
....

page_text: means of copper.
The latter metal is recovered from the sulphate by clectro
deposition. The residue (after lixiviation) must be submitted to amalgamation to
extract the gold and silver left in it in a reguline state.
By converting the metals contained in the ore into oxides the gold and silver are
left also in a reguline state, and aro easily extracted by amalgamation.
To hasten the process of amalgamation I moisten the pulp with a solution of
caustic alkali, and connect the stirring apparatus of the amalgamating pan with
the negative pole of a galvanic battery or other generator of electricity, the pan
itself being connected with the positive pole. In some instances it may be prefer-
able to convert the metals to be extracted into chlorides. For this purpose I pass
through the furnace in which the ore is roasted a current of chloride of sodium
vapor, together with air or oxygen.
The chlorides are dissolved, and those of gold and silver contained in the lye are
either converted into iodides by means of a salt of iodine, or the gold is first
reduced by tannic acid, and then the silver is reduced either by tannic acid or by
electrolytic action in using as a cathode a plate of copper or iron.
If low grade silver ores, tailings, and the like are to be treated I first roast the
ore in order to expel the arsenic and the greatest part of the sulphur. I then mix
The steam, in
the pulverized ore with salt and alum, and admit steam to the mass.
combination with the alum, which acts as an acid, decomposes the salt and converts
the silver into chloride.
Morcover, the precious metals may be extracted from the chlorides by amal-
ganation. In this case I add to the mercury sub-chloride of sodium, which being
converted into chloride by the action of the chlorine, combined with the precious
metals, leaves the latter in a very favorable condition for amalgamation, and
prevents any loss of mercury by formation of calomel.
In refining bullion 1 adopt the same process as that employed for the treatment
of sulphates after the bars have been treated with sulphuric acid.
In order to free the gold from osmium iridium I dissolve the latter in soda lye
by using the bar as an anode or positive electrode.
According to my Invention the conversion of metallic sulphurets into sulphates.
by means of ozone is effected in the following manner:-The powdered ore, mixed
with coarser ore, is introduced in a vessel of suitable shape lined inside with
inoxidable material. I prefer to use a vessel in the form of an inverted cone,
which is inserted in another vessel filled with water. There is an opening at the
bottom of the said cone, through which the ore is discharged, and which is provided
with a door or lid. The top of the cone is hermetically closed by a cover provided
with a man-hole, through which the ore is introduced into the said vessel. The
conical vessel communicates with the outer vessel by means of holes made in the
wall of the conc level with the bottom of the outer vessel in order to allow the
water to rise in the cone and wet the ore. The outer vessel is formed of cast or
shect iron, and is provided with a steam jacket and with a cock level with the
bottom of the same.
The cover of the man-hole of the cone is provided with one or more orzonisators,
that is to say, apparatus through which the oxygen is admitted, converting the
same during its passage into ozone by a continuous silent discharge of electricity.
The oxygen, by passing as ozone into the cone, presses down the water, and as
soon as it comes into contact with the wet or moist ore it oxidises the sulphurets,
converting them into sulphates. As during this process condensation of the ozone
takes place the water again rises in the cone.
A gauge placed in the outer vessel allows the progress of the oxidation to be
observed; when no further variation of the level of this guage is observed the
operation is finished, that is to say, all oxidable matter contained in the ore has
been oxidised and all the sulphurets have been converted into sulphates. Steam is
then introduced into the jacket and into the cone by means of a pipe connected
with the cover. The greater part of the sulphates of copper, iron, zine, and other
metals have been already dissolved during the process of ozonisation, and as the lye

page_text: always contains a certain amount of free sulphuric acid, the sulphate of silver is
readily dissolved by the action of the steam.
The lye is run off into another vessel with double walls and a double bottom.
A current of cold air is passed through, and when by this cold air current or by
other means the temperature of the lye is brought down to about 4° Celsius, the
sulphate of silver crystallizes out; the silver is reduced from the sulphate by melting
it in a crucible. The other metals contained in the lye, such as copper, zinc, or
iron are separated from each other in the ordinary way or by electro-deposition.
The residue in the conical vessel contains all the gold in a free state ready for
amalgamation. The process of oxidation is not performed by the wet method liko
the above described process of ozonisation, but by the dry method by eliminating
the sulphur by hydrogen and by burning afterwards the metals to oxides, leaving
the gold and silver in a reguline state.
The apparatus for this purpose consists of a retort or a series of retorts of
fire-clay similar to those used in the manufacture of illuminating gas, about 6
feet high, of circular or elliptical section inserted in a furnace. The lower part of
the retort has a conical form, and is separated from the upper part at the level
of the door by a perforated plate of fire-clay. The bottom of the cone is pro-
vided with two pipes, a large air pipe and a smaller pipe, through which
hydrogen or oxygen is admitted to the retort, the flow of the air and of the gases
being controlled by means of cocks. The vapors of combustion are conducted
through a pipe connected with the top of the retort into a reservoir where they
are condensed.
Instead of admitting the gases through the said perforated bottom they may be
introduced into the retort through a pipe passing from the top nearly to the bottom
of the retort or by any other suitable arrangement. In order to prevent any
obstruction of the perforated bottom by the fine particles of the powdered orc, a
layer of coarser ore is first placed on the perforated plate. I first heat the ore in
the retort to redness, the cock of the air pipe being open; then this cock is turned
off, and that one of the smaller pipe as well as that of the hydrogen gas holder are
turned on, and a current of hydrogen is passed through the retort. At this stage of
process arseniuretted and sulphuretted hydrogen are evolved. When no more of
these compound gases are produced the cock of the hydrogen gas holder is closed
and that of the oxygen gas holder is turned on; allowing first a small quantity of
oxygen to flow through the retort and increasing the supply thereof at the end of
the operation. The quantity of gas supplied depends entirely upon the per-centage
of oxidable metals contained in the orc.
the
All the metals except gold and silver are oxidised and converted into oxides.
As gold does not oxidise in oxygen even at the highest temperature, and as peroxido
of silver cannot exist at such a high temperature these two metals are left in the
ore in a reguline state, and can be easily extracted by amalgamation.
In some instances as above stated it may be preferable to convert the metals to
be extracted into chlorides. The chloridizing furnace is a revolving furnace of the
following description, that is to say-A cylinder of sheet iron of suitable length
and diameter is lined with brickwork of fire-clay, carbon, or plumbago, provided with
flanges, either parallel or diagonal, or radially inclined, to the axis of the cylinder.
A damper placed between the fire-box and the cylinder serves to close the flue, the
gaseous products of combustion then passing through a large pipe extending over
the cylinder and connecting the top of the fire-box with the chimney. In the
centre of the damper a small circular hole is cut. On the opposite side of the
cylinder towards the chimney is placed a second damper. The groove in which the
end of the cylinder revolves near the fire-box is provided with two pipes like thoso
of the retorts above described and for the same purpose. When the interior of
the cylinder has been heated to redness the pulverized ore is introduced into tho
cylinder through a man-hole, and the said cylinder is now caused to revolve slowly
allowing the flame and a current of air to pass through it. After a short time the
dampers are closed and a crucible of suitable size filled with salt and hermetically

page_text: closed by a cover provided with a bent pipe is placed on the fire-grate, so that the
end of the pipe passes through the hole of the damper. The chloride of sodium
vapour flows into the cylinder and the ore retained by the flanges is continually
falling through the cylinder like spray, whereby a perfect chloridation without any
waste of salt is obtained. When the chloridation is completed the orc is discharged
from the cylinder; it is then lixiviated and the lye treated as above described.
The above described furnace is applicable for the puddling of iron and steel and
other like operations including the refining of iron, copper, and other metals. For
these purposes I sometimes pass hydrogen or other gases or vapors through the said
furnace while the same is rotating.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Richard Werdermann in the Great Scal Patent Office on the 5th
October 1876.
RICHARD WERDERMANN, of Princes Street, in the County of Surrey, Civil
Engineer. "IMPROVEMENTS RELATING TO THE EXTRACTION OF GOLD, SILVER, AND
OTHER METALS FROM ORES AND OTHER SUBSTANCES, AND IN APPARATUS THEREFOR,
WHICH APPARATUS IS APPLICABLE FOR OTHER PURPOSES."
My Invention relates to improved methods of and apparatus for the extraction
of gold, silver, and other metals, from their ores, tailings, and other substances.
The extraction of gold and silver from ores in which the precious metals are
contained in a free state does not present any difficulty, but many gold ores, silver
ores, and auriferous silver ores, principally those which contain arsenic and
antimony, or complex arseniuretted and antimoniuretted combinations of metals,
resist all hitherto known methods of treatment and give up only a portion of the
precious metals they contain.
The various ores are so different in character that it would not be advantageous
to treat all of them in the same manner, and therefore it is necessary to first
ascertain by analysis of the ore which method or process is best suited for tho
extraction of the precious metals from the same. This is especially necessary with
regard to silver ores.
My improved process of treating these ores, especially sulphurets and other
refractory ores, is as follows, that is to say:-I first convert the sulphurets into
sulphates by means of ozone, or into oxides by means of oxygen, or ozone after
elimination of the sulphur and arsenic or part of them by bydrogen. The sulphates
are lixiviated and the sulphate of silver is extracted from the lye by crystallization
produced by cold, or the silver is extracted by electro deposition or reduced by
means of copper. The latter metal is recovered from the sulphate by electro
deposition or by treatment with iron. The residue (after lixiviation) must be
subjected to amalgamation to extract the gold and silver left in it in a reguline
state.
By converting the metals contained in the ore into oxides the gold and silver are
left also in a reguline state, and may be easily extracted by amalgamation.
To accelerate the process of amalgamation I moisten the pulp with a solution of
caustic alkali and connect the stirring apparatus of the amalgamating pan with the
negative pole of a galvanic battery or other generator of electricity, the pan itself
being connected with the positive pole. If the amalgamation is effected in a sluice
the mercury in the same is connected at one end with the positive pole and at
the other end with the negative pole of a galvanic battery, for the purpose of pro-
ducing a more rapid amalgamation. In some instances it may be preferable to
convert the metals to be extracted into chlorides. For this purpose, I pass through
the furnace in which the ore is roasted a current of chloride of sodium vapour
together with air or oxygen.

page_text: The chlorides are dissolved and those of gold and silver contained in the lye
arc either converted into iodides by means of a salt of iodine, or the gold is first
reduced either by tannic acid or by a tannate of an alkali; then the silver is reduced
either by the same process or by electrolytic action in using as the cathode a plate
of copper or iron.
If low grade silver ores or tailings and the like are to be treated, I first roast
the ore in order to expel the arsenic and the greater part of the sulphur. I then
mix the pulverized ore with salt and alum and admit steam to the mass. The
steam in combination with the alum, which acts as an acid, decomposes the salt, and
converts the silver into chloride.
Moreover, the precious metals may be extracted from the chlorides by amalga-
mation. In this case, I add to the mercury subchloride of sodium which being
converted into chloride by the action of the chlorine combined with the precious
metal, leaves the latter in a very favorable condition for amalgamation and prevents
any loss of mercury by the formation of calomel.
In refining bullion I adopt the same process as that employed for the treatment
of sulphates after the bars have been treated with sulphuric acid.
In order to free the gold from osmium iridium I dissolve the latter in soda lyc
by using the bullion bar or lump as an anode or positive electrode.
According to my Invention the conversion of metallic sulphurets into sulphates
by means of ozone is effected in the following manner, that is to say:-The
powdered ore, mixed with coarser ore, is introduced into a vessel of suitable shape,
lined inside with inoxydable material. I prefer to use a vessel of the form of an
inverted cone which is inserted in another vessel containing water. There is an
opening at the bottom of the said cone through which the ore is discharged, and
which is provided with a door or lid. The top of the said cone is hermetically
closed by a cover, provided with a man-hole through which the ore is introduced
in the said vessel. The conical vessel communicates with the outer vessel by means
of holes made in the wall of the cone, level with the bottom of the outer vessel, in
order to allow the water to rise in the said cone and wet the ore. The outer vessel
is formed of cast or sheet iron lined with clay, and is provided with a steam jacket
and with a cock level with the bottom of the same.
The cover of the man-hole of the cone is provided with one or more ozonisers
(ozoninators), that is to say, apparatus through which the oxygen is admitted, con-
verting the same during its passage into ozone by a continuous silent discharge of
electricity.
The oxygen by passing as azone into the cone presses down the water, and as
soon as it comes into contact with the wet or moist ore it oxidises the sulphurets,
converting them into sulphates, as during this process condensation of the ozone
takes place the water again rises in the cone.
A gauge placed in the outer vessel allows the progress of oxidation to be observed;
when there is no further variation of the level of this gauge the operation is
finished, that is to say, all the oxidable matter contained in the ore has been
oxidised, and all the sulphurets have been converted into sulphates. Steam is then
introduced into the jacket and into the cone by means of a pipe connected with
the cover. The greater part of the sulphates of copper, iron, zinc, and other metals,
have been already dissolved during the process of ozonisation, and as the lye
always contains a certain amount of free sulphuric acid, the sulphate of silver is
readily dissolved by the action of steain.
The lye is run off into another vessel with double walls and a double bottom; a
current of air is passed through the same, and when by this cold air current or by
other means the temperature of the lye is brought down to about 4 degrees
Celsius the sulphate of silver crystallises out. The silver is reduced from the
sulphate by melting it in a crucible; the other metals contained in the lye, such as
copper, zinc, and iron, are separated from each other in the ordinary way, or by
electro deposition. The residuum in the conical vessel contains all the gold in a
free stato ready for amalgamation. But although I may accomplish this part of

page_text: my process by the apparatus above described, yet I prefer to use for this purpose
the apparatus shewn in Figure 1, which is a vertical section of the same.
It will be seen that this apparatus resembles in its form and construction an
ordinary blast furnace. a is the brick work; bis the reservoir or tank; c is a per-
forated plate; d is a clay pipe fitted with an ozonizing apparatus; c, c, are wires; f
is an induction coil; g is the oxygen feed pipe; h is a water discharge cock; i is a
reservoir or tank into which the liquid is discharged from the tank b when the
cock is opened; % is a pipe through which the water is raised from the tank i; lis
a door by which the ore is discharged ready for amalgamation. The water
descending through the ore in the apparatus dissolves the sulphates, and is received
in the tank b and flows thence into the reservoir i, and is pumped up through the
pipe and again discharged into the top of the furnace, and is used repeatedly
until saturated with the sulphates, so that it will not dissolve any more of the
saine, and then treated for the extraction of the metals contained in it, as abovo
described, and then a fresh quantity of water is used in the said apparatus.
The process of oxidation is not performed by the wet method like the above-
described process of ozonisation, but by the dry method by eliminating the sulphur
by hydrogen, and afterwards burning the metals to oxides, leaving the gold and
silver in a reguline state.
The apparatus employed for this purpose consists of a retort or a series of
retorts of fire-clay similar to those used in the inanufacture of illuminating gas,
preferably about 6 feet high, of circular or elliptical section and placed in a suitable
furnace. The lower part of the retort has a conical form and is separated from the
upper part of the level of the door by a perforated plate of fire-clay. The bottom
of the cone is provided with two pipes, a large air pipe and a smaller pipe through
which hydrogen or oxygen is admitted to the retort, the flow of the air and of the
gases being controlled by cocks. The vapours of combustion are conducted through
a pipe connected with the top of the retort into a reservoir where they are
condensed.
Instead of admitting the gases through the said perforated bottom they may be
introduced into the retort through a pipe passing from the top nearly to the bottom
of the said retort, or by any other suitable arrangement. In order to prevent any
obstruction of the perforated bottom by the fine particles of the powdered ore a
layer of coarser ore is first placed on the perforated plate. I first heat the ore in the
retort to redness, the cock of the air pipe being open. Then this cock is turned off,
and that one of the smaller pipe as well as that of the hydrogen gas holder are
At this stage of
turned on, and a current of hydrogen passed through the retort.
the process arseniuretted and sulphuretted hydrogen are evolved. When no more
of these compound gases are produced the cock of the hygrogen gas holder is closed,
and that of the oxygen gas holder is turned on, allowing first a small quantity of
oxygen to flow through the retort, and increasing the supply thereof at the end of
the operation. The quantity of gas supplied depends entirely upon the per-centage
of oxidable metals contained in the ore.
All the metals, except gold and silver, are oxidized and converted into oxides. As
gold does not oxidise in oxygen even at the highest temperature, and as peroxide of
silver cannot exist at such a high temperature, these two metals are left in a reguline
state, and can be easily extracted by amalgamation.
In some instances, as above stated, it may be preferable to convert the metals to
be extracted into chlorides. The chloridizing furnace is a revolving furnace con-
structed as shewn in Figures 2 and 3, that is to say, a cylinder m of sheet iron of
suitable length and diameter is lined with fire-brick, fire-clay, carbon, or graphite,
as shewn at n, and is provided with flanges o. These flanges may be either radial
or inclined in transverse section to the axis of the cylinder, and may be either
parallel or spiral or oblique longitudinally to the axis of the said cylinder. A
damper placed between the fire-box and the cylinder serves to close the flue, the
gaseous products of combustion then passing through a large pipe extending over
the cylinder, and connecting the top of the fire-box with the chimney. In the

page_text: centre of the damper a small hole is cut. On the opposite side of the cylinder near
the chimney is placed a second damper. The groove in which the end of the
cylinder revolves is provided with two pipes like those of the retorts above described,
and for the same purpose. When the interior of the cylinder has been heated to
redness the pulverized ore is introduced into the cylinder through a man-hole, and
the said cylinder is now caused to revolve slowly, allowing the flame and current of
air to pass through it. After a short time the dampers are closed, and a crucible of
suitable size filled with salt and hermetically closed by a cover provided with a
bent pipe is placed on the fire-grate, so that the end of the pipe passes through the
hole of the damper. The chloride of sodium vapor flows into the cylinder, and the
ore retained by the flanges descends continually through the cylinder like spray,
whereby a perfect chloridation without any waste of salt is obtained. When the
chloridation is completed the ore is discharged from the cylinder and lixiviated, and
the lye treated as above described (or the ore is submitted to amalgamation).
The above described furnace is applicable for the puddling of iron and steel and
other like operations, including the refinery of iron, copper, and other metals; for
these purposes I sometimes pass hydrogen or other gases or vapours through the
said furnace while the same is rotating.
Having thus fully described my said Invention, and the manner of performing
the same, I wish it understood that I claim the improvements relating to the
extraction of gold, silver, and other metals from ores and other substances, and
comprising,
First. The conversion of. sulphurets into sulphates and the oxidation of the ores
by means of ozone or oxygen, for the purpose above specified.
Second. In the process of amalgamation the moistening of the pulp with a solu-
tion of caustic alkali, as above set forth and for the purpose specified.
Third. In the amalgamation of ores in a sluice the arrangement in which the
mercury at the opposite ends of the same is connected with the opposite poles of a
galvanic battery, as above set forth and for the purpose specified.
Fourth. Passing a current of chloride of sodium vapour through the furnace in
which the ore is roasted, as above set forth and for the purpose specified.
Fifth. The reduction of gold or silver either by means of tannic acid or by means
of the tannate of an alkali, as above set forth.
Sixth. Mixing pulverized silver ore with salt and alum, and admitting steam to
the mass, as above set forth and for the purpose specified.
Seventh. Freeing gold from osmium iridium by dissolving the latter in soda lyc,
and using the bullion bar or lump as an anode or positive electrode, as above set
forth.
Eighth. A rotary furnace provided with flanges or ribs either radial, as shewn in
Figure 2, or inclined, as in Figure 3, and extending either straight or spirally
through the furnace, as above set forth and for the purposes specified.
In witness whereof, I, the said Richard Werdermann, have hereunto set my
hand and seal, this Fifth day of October, in the year of our Lord One
thousand eight hundred and seventy-six.
R. WERDERMANN. (L.S.)