IMPROVEMENTS IN THE TREATMENT OF ORES OR COMPOUNDS CONTAINING COPPER, AND THE SEPARATION OF COPPER FROM PRECIOUS METALS, AND IN APPARATUS CONNECTED THEREWITH
Year: 1880

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, for an Invention of "IMPROVEMENTS IN
THE TREATMENT OF ORES OR COMPOUNDS CONTAINING COPPER, AND THE
SEPARATION OF COPPER FROM PRECIOUS METALS, AND IN APPARATUS
CONNECTED THEREWITH." A communication from abroad by Paul Gustave
Louis Gabriel Designolle, of Paris, in the Republic of France.
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 23rd December 1880.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN THE TREATMENT OF ORES OR COMPOUNDS
CONTAINING COPPER, AND THE SEPARATION OF COPPER FROM PRECIOUS METALS,
AND IN APPARATUS CONNECTED THEREWITH." A communication from abroad
by Paul Gustave Louis Gabriel Designolle, of Paris, in the Republic of France.
This Invention relates to an improved process for treating copper ores containing
precious metals, and it consists, first, in the application of the system of electro
chemical amalgamation, in respect of which Letters Patent were granted to me,
dated February 5th, 1880, No. 507, to the purpose of effecting the simultaneous
extraction of the copper contained in the said ores, and of the precious metals
which may also be present in certain proportions; and, secondly, in simple and
practical means hereinafter described, for separating the copper and precious metals
when united together in a complex amalgam, obtained either by electro chemical
amalgamation or by trituration with metallic mercury.
It has been ascertained that when cupreous matts or sulphurous ores containing
copper, gold, and silver, are treated according to the patented process of electro
chemical amalgamation hereinbefore referred to (that is to say, by bichloride of
mercury, with the addition of a certain quantity of chloride of sodium in the presence
of iron), an amalgam is obtained containing copper and precious metals, but the
amalgam is hard, pulverulent and disseminated in the mass when the proportion of
bichloride of mercury does not exceed the quantity normally requisite to obtain

page_text: the theoretical amalgam Cu Hql; this amalgam becomes, on the other hand, pasty
and capable of adhering to the amalgamated plates when a sufficient quantity of
metallic mercury has been added.
It has also been ascertained that the same results are obtained when treating
certain combinations of copper containing precious metals, such as sub sulphuret
of copper (Cu² S), or antimonial arsenical sulpho antimonial sulpho arsenical copper,
and even the oxides of copper (Cu³ O Cu O).
The process is also applicable when the ores only contain copper in one or the
other of these conditions, and does not contain any precious metals.
The improved process relates more particularly to the following points, videlicet :-
A. Treating cupreous matts containing gold and silver with or without lead.
B. Treating grey copper ore containing antimony, arsenic, gold, and silver
directly after a simple roasting process without having recourse to the conversion
into matts.
C. Treating directly for copper, gold and silver substances resulting from the
roasting of certain pyrites employed for the extraction of sulphur in the manu-
facture of chemicals, particularly the pyrites of San Domingo, Tarcis, Rio Tinto, and
others of the same nature.
D. Avoiding the chloridation of the products hereinbefore enumerated by means
of sea salt, as usually practised, and the treatment with iodides or iodurets for
extracting the silver; in fact, the simplicity of the new procsss enables it to be
applied not only to rich ores, but also to such ores as are too poor to be
exparted.
As hereinbefore stated, it has been found that cupreous pyrites containing gold
or silver in more or less considerable proportions are susceptible of electro chemical
amalgamation, without necessitating the employment of a roasting process; they
are still more susceptible of this, if possible, when they have been approximately
freed from sulphur by roasting; in fact, the sub-sulphuret of copper (Cu² S) as well
as the oxide (Cu O) are susceptible of electro chemical amalgamation, and transfer
to the mercury all the copper which they contain.
Consequently it is of little importance whether the sulphuret of copper be
converted by a complete roasting into oxides (Cu² O or Cu O) or not, experience
proving that in either of these conditions it is equally susceptible of amalgamation
by means of the process of electro chemical amalgamation hereinbefore referred to.
The Invention is carried out in the following manner :-
A. The cupreous substances containing precious metals are pulverised or ground
as finely as possible by any suitable means, either when in a dry condition or in
the presence of water. An apparatus for effecting this pulverization, and the
arrangement of the settling tanks which it is preferred to employ for the purposes
of this Invention, as hereinafter more fully described.
This preliminary result having been obtained, the pulverised matter is introduced
into an amalgamator constructed of wrought or cast iron, together with a sufficient
quantity of water to render it semi fluid, and a suitable weight of bichloride of
mercury, with the addition of a certain quantity of chloride of sodium.
This amalgamating apparatus employed presents a great resemblance to the
pulverising apparatus, and is likewise hereinafter more fully described.
In order to reduce to a minimum the quantity of bichloride of mercury employed,
the said quantity should be be calculated at the rate of one equivalent of mercury
to two equivalents of copper; when the materials are rich in precious metals it is
necessary also to allow for the same. It may also be advantageous, in order to
reduce the wear of the metal of which the cylinder of the amalgamator is composed,
to introduce into the said cylinder a certain quantity of iron, either in the condition
of filings or simply in the condition of sponge, as obtained by calcination in
presence of carbon or peroxide of iron (Fe 2 O³), which forms the residue from
roasting pyrites.
It will be understood that under the conditions hereinbefore set forth the
amalgam resulting from the operation does not possess the butyrous consistency,

page_text: sui generis, of theoretical amalgam, as the quantity of mercury contained in the
bichloride only corresponds to half the weight of copper to be dissolved, so that the
amalgamation is merely commenced; in order to complete it, it is necessary to add
to the mass a quantity of metallic mercury equal to that contained in the bichloride
which was employed in the first change.
The total weight of metallic mercury which it is found desirable to add for the
purpose of promoting the proper performance of the subsequent operations should
be about four times greater than that necessary to obtain the theoretic amalgam
(Cu HG).
This supplementary quantity of mercury is added with a view to imparting a
high degree of fluidity to the amalgam to facilitate the reunion in the mass, and
consequently the almost complete separation before the materials are passed through
the apparatus, with alternate stationary and rotating plates for collecting the
amalgam, according to the Specification of the said former Letters Patent.
The treatment in question applied to cupreous ores produces a large quantity of
amalgam, which it would not be possible to collect upon the plates of the collecting
apparatus without risk of serious loss and prejudicing the action of the said
apparatus.
In order to obviate this inconvenience it is proposed to arrange a mixing or
pugging apparatus with two bodies or chambers of special construction, hereinafter
more fully described, between the amalgamator and the apparatus for receiving and
collecting the amalgam B. A quantity of water sufficient to render the mass
perfectly fluid, that is to say, equal to about five times its volume, is added to the
said mass in the pugging apparatus, and the action of the rakes or arms with
which this apparatus is provided causes the globules of amalgam to unite, and
fall into the lower chamber of the apparatus, where they accumulate in consequence
of their great density, so that only the gangue mixed with a few globules of
amalgam remains in the upper part or chamber of the apparatus.
This operation being terminated the liquid in the upper part of the apparatus
containing the said gangue in suspension is drawn off into another special pugging
apparatus arranged above the apparatus with revolving plates for collecting the
small quantity of amalgam contained in this liquid; for this purpose a sufficient
quantity of water is introduced into this small pugging apparatus in order to
ensure that the mass shall be perfectly liquid when flowing over the amalgamated
plates.
C. The liquid amalgam accumulated in the lower part of the pugging apparatus
is maintained in motion and continually stirred by a helix in presence of a sufficient
quantity of pure water, which is introduced into the apparatus in substitution for
that coutaining the gangue in suspension; this water carries away the impurities
still remaining mixed with the amalgam, which is then, when sufficiently washed,
drawn off to be treated subsequently in conjunction with that collected upon the
revolving amalgamated plates herein before referred to.
The amalgam thus obtained being washed and freed for all impurities, is
subjected to a high degree of pressure in a skin of chamois leather in order to
extract as much of the mercury as possible, after which it is submitted to distillation
in order to drive off the remainder of this metal which still remains associated with
the copper, gold, and silver.
The separation of the copper from the precious metals is also effected during this
distillation, the said separation being based upon an absolutely novel scientific
discovery next hereinafter described.
When a complex amalgam containing copper, gold, silver, platinum, and other
simple bodies belonging to the class of precious metals, is submitted to distillation
in a suitable vessel, the precious metals become separated and descend to the lower
part of the vessel, whilst the copper forms a spongy mass and occupies the upper
part of the said vessel.
A true eliquation of the amalgams is thus produced during the distillation.
When a complex amalgam, in which copper predominates, and such as is herein-

page_text: before described, is submitted to distillation at a little above one hundred degrees,
centigrade, the mass liquiefies, and the amalgams arrange themselves in order, one
upon the other according to their density, the amalgam of copper occupying the
highest position (thus there is no combination between the different amalgams but
a simple mixture). When the temperature is raised to three hundred degrees, the
copper amalgam swells considerably, sweating out drops of mercury, which are
precipitated or commence to become volatilised, whilst the amalgam of the precious
metals remains liquid and occupies the lower part of the vessel.
If the distillation is then proceeded with, the swollen amalgam does not change
its condition; it separates from the mercury finally, leaving a spongy mass clearly
separated from the precious metals, which, also separated from the mercury with
which they were associated, occupy the lower part of the vessel.
The spongy copper being capable of being readily cut with a knife, it is then
simply necessary to divide the cake thus obtained along the clearly defined line of
demarcation between the copper and the precious metals.
The spongy copper being chemically pure is melted and cast in bars for sale, or if
preferred the fusion may be dispensed with, a high degree of pressure being
sufficient to agglomerate it into ingots.
The pinions metals still retaining a small amount of copper are in a most
favorable condition for being refined.
In order to ensure success in carrying out the operation, it is necessary to observe
the following conditions, viz. :-
1st. That amalgam of copper predominates even to a considerable amount (one
hundred times greater) in proportion to the amalgam of gold and silver.
2nd. That before being submitted to distillation the complex amalgam is
powerfully compressed.
3rd. That the distillation is conducted at starting very slowly and with great
care, and that the temperature during the whole operation is not allowed to exceed
from four hundred to five hundred degrees. An apparatus of great simplicity
which enables these conditions to be fulfilled is hereinafter described.
The grinding or pulverizing apparatus is composed of a cast iron drum or cylinder,
which may be made in two pieces to facilitate its transport. This drum is capable
of rotating on a horizontal axis, and is provided with a toothed wheel driven by a
pinion actuated by suitable driving pulleys. This drum contains a number of metal
cylinders, the diameter of which is in proportion to the hardness of the ore and the
internal dimensions of the drum.
A suitable quantity of materials to be pulverized and water is introduced into
the drum, which is then caused to revolve, and when the operation of pulverization
is completed a suitable valve at one end of the drum operated by a handwheel is
opened, whereupon the liquid portion contained in the upper part of the drum is
discharged, whilst the insufficiently ground materials remain in the apparatus in
order to be ground over again with a fresh supply of ore and water introduced into
the apparatus.
A funnel or hopper is arranged underneath the valve in the end of the drum,
and serves to conduct the liquid to several vessels or settling tanks with or without
agitators in the neighbourhood of the drum, in which vessels the products from the
grinding apparatus are deposited in order of fineness, the parts which are too coarsely
ground being returned to the drum to undergo a second pulverisation.
The last one of the series of settling tanks terminates in a double perforated
partition enclosing sponges, which only allow the clear liquid to escape, all the solid
matter, including even the finest particles, being retained in the vessel.
The ground material or pulp thus obtained is introduced into an amalgamating
apparatus similar to the apparatus hereinbefore described, the contents being
however discharged at the lower part of the drum so that the whole of the amalgam
is drawn off at once. For this purpose the cylinders in this apparatus are pro-
vided with helical grooves in such a manner that they only bear upon the internal
periphery of the drum at certain isolated points, and consequently enable the

page_text: amalgam to escape with facility through suitable plugholes provided for the purpose
in the bottom of the drum.
The form and arrangement of this apparatus may be modified if considered
desirable.
The pugging or mixing apparatus is constructed with two bodies or chambers
which serve to retain the greater part of the amalgam before causing the materials
containing the said amalgam to pass through the apparatus with revolving plates
for collecting the amalgam herein before referred to.
This mixing apparatus consists essentially of two cylindrical chambers, an upper
chamber, and a lower and smaller chamber. The upper or larger chamber is
provided with a rake or stirrer of cast iron turning upon a vertical shaft or axis,
having for its object to maintain in suspension in the water the materials delivered
by the amalgamators.
The same vertical shaft or axis also actuates a cast iron helix in the smaller and
lower cylindrical chamber, which helix serves to maintain the amalgam collected in
this chamber in continual motion in order to promote the washing of the materials
and their separation from the gangues.
The mud contained in the upper chamber is discharged separately through
suitable valves, and is conducted to an ordinary mixing or pugging apparatus
before being treated in the apparatus with revolving plates, which latter collects
the last remaining parts of amalgam still held in suspension in the said mud. The
amalgam collected in the lower chamber is discharged through a suitable valve
provided for this purpose.
The novel forn of distilling apparatus employed according to this Invention for
effecting the distillation of the complex amalgam and the separation of the precious
metals consists of a cast iron case constructed as hereinafter described, being
arranged in the interior of a furnace of any suitable construction provided with a
moveable plate or door, facing a corresponding plate in the side of the cast iron
vessel, in order to enable a species of cast iron crucible of rectangular form to be
introduced into the interior of the said vessel. The lower part of the crucible is in
the form of an inverted truncated pyramid, in which the precious metals accumu-
late, the copper remaining in the upper part of the crucible in the condition of
spongy metallic froth.
The crucible is mounted or suspended upon rollers running upon rails attached
to the cast iron vessel or case hereinbefore described for the purpose of enabling
the crucible to be drawn out of the vessel on to a suitable carrier or travelling
platform.
The cast iron vessel is surmounted by a cover provided with a pipe for the escape
of the mercurial vapours resulting from the distillation of the amalgam, and which
are condensed in a refrigerator of any suitable construction.
The crucible being suitably coated internally or lined with peroxide of iron, the
cake obtained does not adhere to the cast iron, but may be withdrawn in a block,
after which it is simply necessary to cut off the base in the form of a truncated
pyramid in order to divide the precious metal from the copper, as hereinbefore
described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Henry Johnson in the Great Seal Patent Office on the
17th June 1881.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS IN THE TREATMENT OF ORES OR COMPOUNDS
CONTAINING COPPER, AND THE SEPARATION OF COPPER FROM PRECIOUS METALS,
AND IN APPARATUS CONNECTED THEREWITH." A communication from abroad
by Paul Gustave Louis Gabriel Designolle, of Paris, in the Republic of France.
The said Invention relates to an improved process for treating copper ores con-
taining precious metals, and consists, first, in the application of the system of
electro chemical amalgamation, as described in the Specification to Letters Patent
granted to me dated the Fifth February, One thousand eight hundred and eighty,
No. 507, to the purpose of effecting the simultaneous extraction of the copper
contained in such cupreous ores and of the precious metals which may also be
present in certain proportions; and, secondly, in simple and practical means herein-
after described for separating the copper and precious metals when united together
in such complex amalgam obtained either by electro chemical amalgamation or by
trituration with metallic mercury.
It has been ascertained that when cupreous matts or sulphurous ores containing
copper, gold, and silver are treated according to the patented process of electro
chemical amalgamation hereinbefore referred to (that is to say, by bichloride of
mercury with the addition of a certain quantity of chloride of sodium in the
presence of iron), an amalgam is obtained containing the copper and precious
metals, but this amalgam is hard and impulverable and disseminated in the mass
when the proportion of bichloride of mercury does not exceed the quantity
normally requisite to obtain the theoretical amalgam Cu Hg'; this amalgam
becomes, on the other hand, pasty and capable of adhering to the amalgamated
plates.
It has also been ascertained that similar results are obtained when treating certain
combinations of copper containing precious metals, such as sub sulphurate of copper
(Cu2 S), or antimonial arsenical sulpho antimonial sulpho, arsenical copper, and
even the oxides of copper (Cu2 O, Cu O).
The process is also applicable when the ores only contain copper in one or the
other of these conditions and does not contain any precious metals.
The improved process relates more particularly to the following points,
videlicit: -
A. Treating cupreous matts containing gold and silver with or without lead.
B. Treating grey copper ore containing antimony, arsenic, gold, and silver,
directly after a simple roasting process without having recourse to the conversion
into matts.
C. Treating directly for copper, gold, and silver substances, resulting from the
roasting of certain pyrites employed for the extraction of sulphur in the manufacture
of chemicals, particularly the pyrites of San Domingo, Tarcis, Rio Tinto, and others
of the same nature.
D. Avoiding the chloridation of the products herein before enumerated by means 4
of sea salt as usually practised, and the treatment with iodides or iodurets for
extracting the silver.
The simplicity of this improved process enables it to be applied not only to
rich ores but also to such ores as are usually too poor in metals to be worth
exportation.
As herein before stated, it has been found that cupreous pyrites containing gold or
silver in more or less considerable proportions are susceptible of electro chemical

page_text: amalgamation without necessitating the employment of a roasting process, and they
are rendered still more susceptible of this when they have been approximately freed
from sulphur by roasting; in fact, the sub sulphurate of copper Cu2S, as well as
the oxide (Cu O), are then susceptible of electro chemical amalgamation, and by
which all the copper contained is transferred to the mercury as an amalgam.
Consequently it is of little importance whether the sulphurate of copper be
converted by a complete roasting into oxides (Cu³ O or Cu O) or not, experience
proving that in either of these conditions it is equally susceptible of amalgamation
by means of the process of electro chemical amalgamation herein before referred to.
And in order that the said Invention may be fully understood I shall now
proceed more particularly to describe the same, and for that purpose shall refer to
the several Figures on the annexed Sheet of Drawings, the same letters of reference
indicating corresponding parts in all the corresponding Figures.
Figure 1 of the accompanying Drawings represents a side elevation of the
grinding or triturating apparatus employed in carrying out this Invention;
Figure 1 is a transverse section of the same, and Figures 1b is a plan section of a
detail hereinafter described in connection with such apparatus.
Figure 2 is a detail in the amalgamating apparatus hereinafter referred to.
Figure 3 is a vertical section of a mixing or pugging apparatus with two
chambers; and Figure 4 is a corresponding plan of the same.
Figure 5 represents a transverse section of the distilling apparatus employed
according to this Invention, and Figure 6 is a longitudinal section of the same.
A. The cupreous substances containing precious metals are pulverised or ground
as finely as possible by any suitable means, either wheu in a dry condition or in
the presence of water. An apparatus for effecting this pulverisation or trituration,
and the arrangement of the settling tanks which it is preferred to employ for the
purposes of this Invention is hereinafter more fully described.
This preliminary grinding operation having been effected the pulverised matter
is introduced into an amalgamator or receptacle constructed of wrought or cast
iron, together with a sufficient quantity of water to render it semi fluid, and a
suitable weight of bichloride of mercury with the addition of a certain quantity of
chloride of sodium.
This amalgamating apparatus is of an analogous nature to the pulverising
apparatus, and is likewise hereinafter more fully described.
In order to reduce to a minimum the quantity of bichloride of mercury employed
this quantity shonld be calculated at the rate of one equivalent of mercury to two
equivalents of copper, but when the ores are rich in precious metals it is also
necessary to make proportionate allowance for the same.
It may likewise be advantageous, in order to reduce the wear of the metal of
which the cylinder of the amalgamator is composed, to introduce into the said
cylinder a certain quantity of iron, either in the condition of filings or simply in
the condition of sponge, such as is obtained by the calcination in presence of
carbon of the peroxide of iron (Fe² O³), which forms the residue from roasting
pyrites.
It will be understood that under the conditions hereinbefore set forth the amalgam
resulting from the operation does not possess the butyrous consistency, sui generis,
of theoretical amalgam, as the quantity of mercury contained in the bichloride only
corresponds to half the weight of copper to be dissolved, so that the amalgamation
is merely commenced; and in order to complete the same it is necessary to
add to the mass a quantity of metallic mercury equal to that contained in the
bichloride which was employed in the first charge.
The total weight of metallic mercury which it is found desirable to add for the
purpose of promoting the proper performance of the subsequent operations should
be about four times greater than that necessary to obtain the theoretic amalgam
(Cu Hg).
This supplementary quantity of mercury is added with a view to imparting a
bigh degree of fluidity to the amalgam to facilitate the reunion in the mass, and

page_text: consequently the almost complete separation before the materials are passed through
the apparatus, with alternate stationary and rotating plates for collecting the
amalgam, as described in the Specification of the Letters Patent dated February Fifth,
One thousand eight hundred and and eighty, No. 507, hereinbefore referred to.
The treatment in question, applied to cupreous ores, produces a large quantity
of amalgam, which it would not be possible to collect upon the plates of the
collecting apparatus without risk of serious loss and prejudicing the action of the
said apparatus.
In order to obviate this inconvenience it is proposed to arrange a mixing or
pugging apparatus, having two receptacles or chambers of special construction, and
which will hereinafter be more fully described.
B. A quantity of water sufficient to render the mass perfectly fluid, that is to
say, equal to about five times its volume, is added to the said mass in the pugging
apparatus, and the action of the rakes or arms with which this apparatus is provided
causes the globules of amalgam to unite and fall into the lower chamber of the
apparatus where they accumulate in consequence of their great density, so that the
gaugue alone mixed with a few globules of amalgam remains in the upper part or
chamber of the apparatus.
This operation being terminated, the liquid in the upper part of the apparatus
containing the said gaugue in suspension is drawn off into another special pugging
or agitating apparatus arranged above the apparatus with revolving plates for
collecting the small quantity of amalgam contained in this liquid; for this purpose
a sufficient quantity of water is introduced into the small pugging apparatus in
order to ensure that the mass shall be perfectly liquid when flowing over the
revolving plates.
C. The liquid amalgam accumulated in the lower part of the pugging apparatus
is maintained in motion by being continually stirred by a helix in presence of a
sufficient quantity of pure water which is introduced into the apparatus in
substitution for that containing the gaugue in suspension; this water carries away
the impurities still remaining mixed with the amalgam, which after sufficiently
washing is drawn off to be subsequently treated in conjunction with that collected
upon the revolving plates hereinbefore referred to.
The amalgam thus obtained, after being washed and freed from all impurities, is
subjected to a high degree of pressure in a skin of chamois leather in order to
extract as much of the mercury as possible, after which it is submitted to
distillation in order to volatilise or drive off the remainder of this metal which still
remains associated with the copper, gold, and silver.
The separation of the copper from the precious metals is also effected during this
distillation, and the said separation being based upon a new scientific discovery
which will be next described.
When a complex amalgam containing copper, gold, silver, platinum, and other
simple bodies belonging to the class of precious metals is submitted to distillation in
a suitable vessel, the precious metals become separated and descend to the lower part
of the vessel, whilst the copper forms a spongy mass of lighter specific gravity
occupies the upper part of the said vessel.
A true eliquation of the amalgam is thus produced during the distillation, being
a phenomenon not heretofore observed, and which admits of the following
explanation, videlicet :-
Copper amalgam when heated to near about three hundred degrees centigrade,
possesses the property of swelling or becoming puffed up, and at the same time
sweating and drops of mercury, whilst gold, silver, platinum, and other metals,
separate from the mercury with which they are associated without swelling.
Therefore when a complex amalgam, in which copper predominates, and such as
is hereinbefore described, is submitted to distillation at a little above one hundred
degrees centigrade the mass liquifies, and the amalgams arrange themselves in order
one upon the other according to their density, the amalgam of copper occupying
the highest position, and thus there is no actual combination effected between the

page_text: different amalgams, but a simple mixture. When the temperature raised to three
hundred degrees, the copper amalgam swells considerably, sweating out drops of
mercury which are precipitated or commence to become volatilised, whilst the
amalgam of the precious metals remains liquid and occupies the lower part of the
vessel.
If the distillation is then proceeded with, the swollen cupreous amalgam does not
change its condition, but it finally separates from the inercury, leaving a spongy mass
clearly separated from the precious metals, which also separate from the mercury
with which they were associated when occupying the lower part of the vessel.
The spongy copper being capable of being readily cut with a knife, it is then
simply necessary to divide the cake thus obtained along the clearly defined line of
demarcation between the copper and the precious metals.
The spongy copper being chemically pure may be melted and cast in bars for
sale, or if preferred the fusion may be dispensed with, a high degree of pressure
being sufficient to agglomerate it into ingots.
The precious metals still retaining a small amount of copper are in a most
favorable condition for being refined.
In order to ensure success in carrying out the operation it is necessary to observe
the following conditions, videlicet:-
-
First. That amalgam of copper predominates even to a considerable amount (say
one hundred times greater) in proportion to the amalgam of gold and silver.
Second. That before being submitted to distillation the complex amalgam is
powerfully compressed.
Third. That the distillation is conducted at starting very slowly and with great
care, and that the temperature during the whole operation is not allowed to exceed
from four hundred to five hundred degrees; and apparatus of great simplicity
which enables these conditions to be fulfilled is hereinafter described.
The grinding or triturating apparatus Figure 1, 18, and 1b, is composed of a cast
iron drum or cylinder a, which may be made in two pieces to facilitate its transport,
and is so suitably mounted as to be capable of rotating on a horizontal axis, motion
being imparted by a toothed wheel b driven by an ordinary pinion, not shown in
the Drawing, actuated by driving pulleys b¹.
This drum contains a number of metal cylinders c, Figures 1° and 1b, five of
which are shown in the Drawing, and the diameter of which is duly proportioned
to the hardness of the ore and the internal capacity of the drum.
A suitable quantity of the materials to be pulverised and water is introduced
into the drum, which is then caused to revolve, and when the grinding or trituration
is completed, a valve d operated by a hand wheel e is opened, whereupon the liquid
portion contained in the upper part of the drum is discharged, whilst the
insufficiently triburated materials remain in the apparatus in order to be further
reduced with a fresh supply of ore and water introduced into the drum as
before.
A funnel or hopper f is arranged underneath the valve d in the end of the drum,
and serves to conduct the liquid to several vessels or settling tanks, with or without
agitators or stirrers provided in the neighbourhood of the drum in which the
products from the triburating apparatus are deposited in order of fineness, the
parts which are too coarsely ground being returned to the apparatus.
The last one of the series of settling tanks terminates in a double perforated
partition enclosing sponges which only allow the clear liquid to escape, all the
solid matter, including even the finest particles held in suspension, being retained
in the tank.
The ground material or pulp thus obtained is introduced into an amalgamating
apparatus similar to the triturating apparatus hereinbefore described, the contents
being however discharged at the lower part of the drum, so that the whole of the
amalgam is drawn off at once. For this purpose the internal cylinders in this
apparatus are provided with helical grooves, as shown in Figure 2, in such a
manner that they bear upon the internal periphery of the drum at certain isolated

page_text: points only, and consequently enable the amalgam to escape with facility through
suitable plug holes provided for the purpose in the bottom of the drum.
The form and arrangement of this apparatus may however be modified if con-
sidered desirable.
The pugging or mixing apparatus represented in Figures 3 and 4 is constructed
with two bodies, receptacles, or chambers, and serves to retain the greater part of
the amalgam before causing the materials containing the said amalgam to pass
through the apparatus with revolving plates for collecting the amalgam herein before
referred to.
This mixing apparatus consists essentially of an upper cylindrical chamber A,
and a similar lower one B of smaller diameter. The upper or larger chamber A is
provided with a cast iron rake or stirrer C of cast iron turning upon a vertical
shaft or axis D provided for agitating the water, and maintaining in mechanical
suspension the triturated materials delivered by the amalgamator or amalgamators.
The same vertical shaft or axis also actuates a cast iron helix or screw E in the
smaller and lower cylindrical chamber B, which helix or screw serves to maintain
the amalgam collected in this chamber in continual motion, in order to promote the
washing of the materials and their separation from the gangues.
The mud contained in the upper chamber A is discharged separately through
valves F, F, and is conducted to an ordinary mixing or pugging apparatus before
being treated in the apparatus with revolving plates, which latter collects the last
remaining parts of amalgam still held in suspension in the said mud. The amalgam
collected in the lower chamber B is discharged through a valve G.
The improved apparatus employed according to this Invention for effecting the
distillation of the complex amalgam and the separation of the precious metals is
represented in Figures 5 and 6, and consists of a cast iron case or chamber H
arranged in the intérior of a furnace I of any suitable construction provided with
a moveable plate or door J facing a corresponding plate J' in the side of the
chamber H, in order to allow a kind of cast iron crucible K of rectangular or other
convenient form to be introduced into the interior of the said chamber. The lower
part of the crucible K is in the form of an inverted truncated pyramid in which
the precious metals accumulate, the copper remaining in the upper part of the
crucible in the condition of spongy metallic froth, as before described.
The crucible K is mounted or suspended upon rollers L running upon rails M
attached to the chamber H for the purpose of enabling the crucible K to be readily
transferred to the interior of the vessel H from a carrier or travelling platform N,
and vice versa.
The chamber His surmounted by a cover O provided with a pipe H¹ for the
escape of the mercurial vapours resulting from the volatilisation or distillation
of the amalgam, and which are condensed in a refrigerator of any suitable
construction.
The crucible K being suitably internally coated or lined with peroxide of iron to
prevent the cakes of copper adhering to the cast iron, so that they may be readily
withdrawn in a block, after which it is simply necessary to cut off the base in the
form of a truncated pyramid in order to divide the precious metal from the copper,
as herein before described.
Having now described and particularly ascertained the nature of the suid
Invention and the manner in which the same is or may be used or carried into
effect, I would observe in conclusion that what I consider to be novel and original
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is,-
First. The treatment for the reduction or separation of copper and the precious
metals contained in cupreous ores or compounds containing copper by the application
of the process of electro-chemical amalgamation, in which the ores having been
reduced to a fine state of division by pounding, grinding, or triturating, are treated
with bichloride of mercury with the addition of sodium chloride in the presence of
metallic iron, substantially as hereinbefore described.

page_text: Second. Completing the preliminary amalgamation obtained by the process
herein before referred to so as to render the amalgam pasty or susceptible of
agglomeration for adhering to the amalgamating plates provided for its reception
by the addition of metallic mercury introduced into the mass after the commence-
ment of amalgamation, substantially as herein before described.
Third. The method of preliminarily separating the greater part of the amalgam
produced by decantation, subsidence, and filtration, substantially as hereinbefore
described.
Fourth. Separating the precious metals contained in a complete amalgam of
copper by volatilisation or distillation of the mercury contained therein, by which
the metals most tenacious of mercury gravitate, while the copper ascends to the
surface according to the phenomenon of eliquation, substantially as hereinbefore
described.
Fifth. The employment of grinding or triturating apparatus constructed and
arranged so as to operate substantially as and for the purpose herein before
described and illustrated in the accompanying Drawings.
Sixth. The employment of amalgamating apparatus having cylindrical chambers
provided with helical grooves and capable of turning freely within a rotating drum,
substantially as and for the purpose hereinbefore described and illustrated in the
accompanying Drawings.
Seventh. The construction and arrangement of mixing or pugging apparatus
having two bodies or chambers arranged the one over the other, and provided with
agitators for the direct separation of the greater part of the amalgam obtained,
substantially as herein before described and illustrated in the accompanying
Drawings.
Eighth. The arrangement of retort or distilling apparatus having a double case
with metallic crucibles in the form of a truncated cone mounted upon rollers so as
to travel upon rails for the purpose of facilitating the manipulation and transport
of the said crucibles, substantially as herinbefore described and illustrated in the
accompanying Drawings.
In witness whereof, I, the said John Henry Johnson, have to this my
Specification set my hand and seal, the Sixteenth day of June, One
thousand eight hundred and eighty one.
J. HENRY JOHNSON. (L.S.)