Separation and Deposition of Metals.
Year: 1884

page_text: Separation and Deposition of Metals.
I, ALEXANDER MELVILLE CLARK, of the firm of A. M. and Wm. Clark, of
53, Chancery Lane, in the County of Middlesex, Fellow of the Institute of Patent
Agents, do hereby declare the nature of the said Invention for AN IMPROVED
APPARATUS AND PROCESS FOR THE ELECTROLYTICAL SEPARATION AND DEPOSITION'
OF METALS a communication to me from abroad by Bernhard Moebius, of
Chihuahua, Mexico, Metallurgist to be as follows:-
This invention relates to a process and apparatus for refining silver and separating
it from gold, platinum, copper, lead, and other metals by means of electricity, which,
apparatus when slightly modified, can be used in other electrolytical processes for,
the decomposition and precipitation of metals by electricity.
I
In refining silver with this apparatus, the silver to be refined is cast in blocks or
bars provided in the upper edge with threaded, apertures for receiving the ends of
screws which pass freely through a bar or rod having its ends bent up, so as to
adapt them to rest upon the conductors, the bent ends of the bars or rods being
recessed in the bottom to receive the conductors and prevent shifting of the bars.
on the said conductors. The screws are provided at their upper ends with handles
and above the bar winged nuts are screwed on the screws whereby by turning the
said nuts the anodes can be raised or lowered in relation to the bar or rod resting.
on the conductors. The lower parts of the screws are plated with gold or platinum
and when screwed into the upper edge of the anode, they may be provided with a,
coating of varnish to prevent their being acted upon by the solution. The anode
can have any desired shape but it is preferred to make it in the shape of a flat
rectangular block.
The anodes and the cathodes must be respectively held to conducting wires and,
they form the, elements of an electric battery, the solution of which battery is
contained in a liquid proof tank, or box, of which a series are placed in a trough-
shaped vessel which is adapted to receive the liquid and metals which are spilled
by accident or otherwise and rests upon a suitable base. The tanks may be made,
.

page_text: of wood, earthenware, enamelled metal, or other suitable material. In each tank
or box a frame is placed, having four corner standards, each provided in its
upper end with a notch adapted to receive the anode conductors, which can be
held within the notch by a pin passed transversely through apertures in the
upper part of the standard. The standards are united near their upper ends by
horizontal rods provided on their upper edges with upwardly projecting pins placed
at suitable intervals. The said rods, that is, those rods parallel with the anode
conductors, support frames, the end standards of which are provided at their upper
ends with notches adapted to receive the ends of the anode supports, the said
standards being provided at their upper ends with apertures through which pins
are passed for holding the anode supports in place. The standards are united by
two longitudinal rods which rest upon the upper edges of the rods of the outer
frames. Each anode is held in a frame and is surrounded by a bag made of muslin
or other fabric or material that will permit the solution and current to pass through
it, through the seams of which bag, the bars of the frame are passed for the purpose
The outer
of holding the bag surrounding the frame and the anode in the same.
frame is surrounded by a larger bag provided at its upper edges with rings or loops
through which the pins on the bars of the outer frame can be passed for the purpose
of holding the bag stretched over the frame. This bag is also made of muslin,
canvas or other material that will permit the solution to pass.
The cathodes are suspended by means of their wires from the cathode conductors,
which run at right angles to the cathodes and parallel to the longitudinal axis of
the trough. The positive or anode conductors which rest in the notches of the
standards of the outer frames contained in the tanks or boxes, run parallel with
the cathode conductors, but are arranged a short distance below the said conductors
and inside of the same; said conductors are held in transverse bars or strips and
the anode conductors are also held in transverse bars or strips, the former bars or
strips being arranged between the latter and the ends of the cathode conductors
extend beyond their bars and resting on the bars of the anode conductors. The
ends of ropes or belts are secured to the cathode conductors by hooks or snaps or
in any other suitable manner, the said belts or ropes passing through eyes held on
a bar passing longitudinally over the middle of the tanks in one section, the ends
of the said bars being suitably guided by standards to move vertically. The bar.
is suspended from a beam or cylinder, by a series of chains or ropes having their
lower ends suitably connected with the bars. The above mentioned beam, shaft
or roller is journaled in the standards and on one end is mounted a grooved pulley
around which a driving chain or belt passes, which also passes over a pulley pivoted
on the outside of one of the standards, the shaft of the pulley being provided with a
ratchet wheel and a crank, a pawl engaging with the ratchet wheel. Ropes or
straps which may be provided with buckles are passed around the conductors, so
that when the cathode conductors are raised, the anode conductors will be suspended
from the same.
i
In electrolytical processes, that is where metals are decomposed or separated and
deposited by electricity, the elements become polarized, which polarization is caused
by the accumulation of super-oxides or oxygen bubbles on the anodes and hydrogen
bubbles on the cathodes and is also caused by an irregular mixture of the solution.
This irregular mixture produces solutions of metals of different specific gravity,
thereby producing several layers, each layer forming an element, the elements
consisting of one part of metal and two parts of different fluids; and these new
elements' produce a secondary or polarizing current which causes a corrosion of the
cathodes and an'irregular decomposition of the anodes. To prevent this polarization
of the electrodes, I have provided means for agitating the liquid, and these means
consist of shovels or blades hung on the anode conductors and having their lower
wider ends bent inward and downward. The upper end of each agitator is con-
nected by a cord with a frame, which will be described hereinafter.
I prefer to use two agitators for each tank or box and to arrange them in
diagonally opposite corners.
.'

page_text: Each element, that is each cathode and each anode is provided with brushes for
brushing the surface of the same and thus preventing the accumulation of metals
and peroxides and the accumulation of bubbles of hydrogen and oxygen on the
elements, the formation of bridges or metal connections between the electrodes,
and the formation of projections on the cathrodes. This permits of placing the
anodes very close to each other, without any danger of their forming connections
with each other. The brushes are united in pairs, the bristles or pins facing each
other; and at their upper ends the brushes of one pair are united by a screw
spindle having right and left hand threads, so that by turning the said spindle, the
upper ends of the brushes may be moved toward and from each other. Preferably
two pairs of brushes are provided for each anode, and two for each cathode, so
that two brushes will be on each surface of each anode and each cathode. The
brushes are secured near their ends to bars or strips in such a manner that they
can be shifted to be a greater or less distance from each other on the said bars.
The ends of the one set of bars rest in.rabbets, formed in the upper edges of the
longitudinal bars of one frame and the other bars rest in rabbets formed in the
inner upper edges of the longitudinal bars of another framé which is located below
the first frame, and is smaller than the same, so that the inner edges" of the
longitudinal bars of the latter frame will be flush with the vertical sides or backs
of the rabbets formed in the inner edge of the lower frame. Ropes are passed
through the eyes of the bar which is suspended from the beam above mentioned'
and the ends of the ropes are connected with the longitudinal bars of the upper
frane. Ropes or straps which may be provided with buckles are passed around
the longitudinal bars of the frames or in place of straps or ropes other adjusting
devices can be used, said devices being of about the same length as the straps
which pass around the conductors, so that when the upper frames are raised the
lower frames will not be raised with them until the upper frames are a certain
distance above the lower frames. Horizontal bars are held in guides on the inner'
surface of the upper parts of the standards in such a manner that the said bars can
slide in the direction of their length. These bars each have one end connected by
a connecting rod with a worm wheel engaging with a worm revolved by means of
suitable gearing. On each bar two bars are hung, the lower ends of which pass
through vertical slots in the bars of the frames in which the brushes are supported
and below the bottom of the lower frame a key is passed through each vertical rod,
on which keys the frames rest. The vertical bars are each provided with a series
of apertures which permit of adjusting the height of the frames. By means of the'
worm gearing the bars and the brush frames may be reciprocated and the brushes
reciprocated horizontally and parallel with the faces of the anodes and cathodes so
as to brush their surfaces and keep them clean. As the lower frames are recipro-
cated in the horizontal plane, they swing the agitators, thereby swinging their
lower ends upwards, and when the frames return, the weight of the agitators
causes them to swing down.
"
#
In case the elements are to be raised out of the tanks or boxes, the shaft is
revolved by means of the gearing and the ropes are wound on the shaft and thereby
the negative or cathode conductors, and the upper brush frame are raised.
The
object of this arrangement is that when the operation is interrupted, the cathodes'
can be raised very rapidly and are thus protected from being acted upon or
destroyed by the solutions, and at the same time" this construction permits of
immersing the electrodes as much as may be desired, whereby the density of the
current inay be regulated. When the ropes or straps which pass around the frames
and the conductors are drawn taut, the positive or anode conductors and the lower:
brush frame are also raised, the frames in the tank or box and the bags remaining
in the tanks, and when the pins are passed through the apertures in the upper ends
of the standards of the frames, the said frames and the bags held on the same will
also be raised with the anodes and cathodes.
The troughs and the frames, when made of wood, are provided with several
coats of graphite paint and powdered graphite is rubbed on them for the purpose

page_text: of protecting them from being destroyed by salts and acids. By blackleading the
inner frames, they become conductors of electricity and if a contact is made
between the notches and the anode conductors, the current will act on the metals
brushed from the anodes and lying on the bottom of the frame; whereby remnants
of the per oxide and metallic silver which may still be present are dissolved and
extracted. The sacks or bags which receive the gold, silver, etc., are saturated
with a solution' of coal oil, linseed oil, and paraffine, whereby they are rendered
very pliable and can resist the action of the acids and salts. Those parts of the
conductors which come in contact with the frames, the tanks, etc. are provided
with rubber insulators.
The operation is as follows:-
As stated above, the base bullion to be refined, is cast in the shape of suitable
blocks or plates for anodes. As cathodes, I use silver coated copper plates, which
give nearly the same results as silver plates but are less expensive. Pure copper
cathodes are not advisable as they destroy the exciting liquid in precipitating by
simple immersion, the silver contained in the solution.
The exciting liquid employed consists of a solution of nitrate of silver, nitrate
of copper and nitric acid, and may be formed in the battery, by adding diluted
nitric acid which dissolves the silver and copper contained in the bullion to be refined.
Obtaining the correct solution is ascelerated by arranging the electrodes in such
a manner that the cathodes dip but slightly into the exciting liquid; whereby
more silver is dissolved than is precipitated by the cathodes. The presence of
copper in the solution is necessary to ensure the precipitation of all the lead as
peroxide of lead at the anodes. Oil is rubbed on the cathodes to prevent the
adhesion of the silver. The current, which must be of small electro-motive force
(from one to three volts per cell) dissolves the silver and precipitates it at the
cathodes in a loose spongy state, or in a crystalline shape, according to the con-
centration of the solution, and the density of the current. The silver drops from
the cathodes to the bottom of the receptacles or bags in which it collects. The
copper is dissolved also, but as it is less electro-negative, it remains in solution,
provided the exciting liquid is not too poor in silver and too rich in copper. But
even if some copper should be precipitated with the silver it would be removed
with the same from the cathodes and as it comes in contact with the silver solution
in the bottom of the receptacle, it would redissolve and precipitate its equivalent
of silver. The lead as per oxide as well as the gold, platinum, antimony, and
variable quantities of per-oxide of silver, are precipitated at the anode, from which
they are continually removed and are caught and retained in the bags surrounding
the anodes. In carrying out this operation, the brushes above described are very
effective, as they continually remove the silver from the cathodes and thereby
prevent the formation of bridges or metallic connections between the electrodes,
and avoid the dropping of silver in the anode or gold bags. The anodes can be
placed very near together, whereby the resistance of the cell is considerably
reduced.
The peroxides formed and precipitated at the anodes, in the course of time form
a thick layer on the same and as they are bad conductors of electricity and produce
secondary currents or polarization in the battery, they would cause a considerable
weakening or waste of the current if they were not removed from the anodes by
the brushes, and collected in the bags provided for this purpose.
In this process, I use only one exciting liquid, and there is no need of a dialyser
such as a porous cell membrane etc, to keep the exciting liquid of the anode
separated from that of the cathode. The bags above described only serve as
receptacles for the metals precipitated at the anodes and may be substituted by
a box or other receiver or receptacle placed under or around each anode. The only
object of this arrangement is to keep the anions and cations separate and not to
let them both drop to the bottom of the tank; consequently it is immaterial
whether the anodes or the cathodes, or both are provided with such boxes or

page_text: .
receptacles. For that reason I do not limit myself in this respect to any special
arrangement for carrying out the process.
1
The anions brushed from the anodes fall to the bottom of the frame and if a
contact of the latter with the anode supporter is established, the current acts upon
the anions whereby remnants of per oxide and of metallic silver and copper, which
may still be present, are dissolved and extracted. This extraction will be more
effective, if the exciting liquid contains a larger quantity of nitric acid. The
antimony, lead, as peroxide of lead and other impurities contained in the silver
remain with the gold from which they are separated by melting, and the peroxide
of lead is thus changed to oxide of lead and all the oxidizable metals are converted
into slags, thus leaving the gold separate from the rest. But if it is desired to
obtain absolutely pure gold devoid of platinum and platinum metals, which are to
be separated from it; the following method may be employed.
The contents of the gold bag are washed and placed in a retort containing
bromine water having a surplus of bromine. The bromine water may advan-
tageously contain bydrobromic acid, which is easily obtained by exposing the
bromine water to the sunlight for some time. The retort is connected with a
receiver which is filled with iron shavings and some water; the gold per oxides etc.
are converted into bromides, the surplus of bromine is distilled into the receiver
filled with iron, and it forms bromide of iron, which is dissolved in the water
contained in the receiver. After diluting the gold solution with cold water it is
conducted from the retort into a tank where the gold is precipitated by the
bromide of iron formed in the receiver. The solution which still contains platinum
metals etc, is then drawn off into another tank in which plates of iron are sus-
pended, by which the platinum metals, lead, copper, etc. are precipitated. The
separation of these metals is then continued in the well known manner.
The remaining solution is devoid of all valuable metals and is evaporated from
the salt obtained (consisting principally of per-bromide of iron) and the bromide
and hydro-bromic acid employed in the process is easily regenerated by treatment
with sulphuric acid.
If the silver contains osmi-iridium it remains with the residuum in the retort,
the said residuum consisting principally of bromide of lead and bromide of silver
is reduced by contact with zinc. Bromide of zinc results and can be used for the
regeneration of bromine. The regeneration is carried out in such a manner that
the bromine and hydrobromic acid is distilled directly into the retort containing
the contents of the gold bags, whereby handling of the bromine and the unpleasant
effects of its fumes are avoided.
If in the course of time, the exciting liquid in the battery becomes too con-
centrated and contains too much copper and not enough silver, the copper will be
precipitated with the silver, and in case this occurs, the solution must be regenerated
in the following manner.
After removing all the electrodes and the anode bags, copper plates or blocks
are hung in the cell, whereby the silver remaining in, the solution is precipitated
in a short time, as the brushes continually remove the silver deposited in a loose
state on the copper plates, and a clean surface of the latter is always exposed.
After having removed the bags surrounding all the electrodes with the pre-
cipitated silver therein, the greater part of the copper in solution is precipitated
by means of a current having a greater electro-motive force, carbon plates being
used as anodes, and copper plates as cathodes.
The density of the current and the nature of the exciting liquid considerably.
affects the quality of the copper liberated at the cathodes and to obtain it in a
regular coherent shape it would require either a very large surface of electrodes
or a weaker current. This would make the plant larger and more expensive or
delay the precipitation too much. For that reason I prefer to use a strong current
with electrodes of ordinary size and thereby precipitate the copper in loose powder
at the cathodes.

page_text: t
As the carbon anode cannot be dissolved, the solution becomes more and more
acid, and this free nitric acid will redissolve the fine copper precipitate on the
bottom of the tank, and thus frustrate the entire operation. To prevent this
I place a large copper plate or box under each electrode and on the bottom of the
tank, and by means of wires bring it into contact with the cathode conductors,
whereby the precipitated copper drops upon this plate and forms a part of the
cathode, increasing its surface and preventing the redissolving of the copper.
The brushes above referred to are also of great service during this operation, as
they remove the bubbles of hydrogen and oxygen that accumulate on the electrodes
and prevent polarization and consequent waste of power.
It would be advisable to use an anode bag in this case also in order to prevent
the hydrogen bubbles arising from the plate below the electrodes from mixing with
the oxygen bubbles at the anodes.
The solution remaining in the bath and now containing much free nitric acid, is
used in the process again, partly for replacing the water evaporated from the tanks
and keeping the exciting liquid sufficiently acidulated and partly for making
a new solution by mixing it with the solution that already contains enough
-silver.
$
If the copper in the alloy amounts to about one third of the silver, the nitrate
of silver in the exciting liquid will be converted into nitrate of copper too rapidly
and then the separation of the silver from the copper, gold etc. in one operation is
no longer practicable. The following preliminary treatment must then be employed
for first extracting the copper from the alloy.
The exciting liquid used in this case consists of an acidulated solution of nitrate
of copper. In place of this, sulphate of copper may be used when the alloy is poor
in silver.
. The anodes are formed of blocks or plates of the alloy and the cathodes of copper
plates. The electric current which must be of small electro-motive force, dissolves
the copper and precipitates it at the cathodes, the silver, gold, platinum lead etc.
remaining at the anodes in a more or less coherent state, according to the com-
position of the alloy. The silver accumulating at the anodes will finally precipitate
to such an extent that it would go into solution also and be precipitated with the
copper, if it were not continually removed, together with the gold, and silver, from
the anodes by the brushes, and thus withdrawn from the dissolving action of the
current. The silver, gold, platinum etc. gathered in the bags are melted and cast
into plates or blocks to be used as anodes and the metals are then separated as
herein before described.
-
The principal advantages of this improved process are as follows:-The operation
is continuous and very simple, a large quantity of silver can be refined very
rapidly and at a very low cost, as the quantity of chemicals required is com-
paratively small; there is no need of filtering and transferring or handling acids
producing noxious or dangerous fumes, the gold and silver obtained are very pure ;
all the platinum metals contained in the gold and silver can be recovered, and
copper is obtained as pure metallic copper.
Dated this 16th day of December 1884

page_text: Separation and Deposition of Metals.
I, ALEXANDER MELVILLE CLARK, of the firm of A. M. and Wm. Clark, of
53, Chancery Lane, in the County of Middlesex, Fellow of the Institute of Patent
-Agents, do hereby declare the nature of the said Invention for "AN IMPROVED
APPARATUS AND' PROCESS FOR THE ELECTROLYTICAL SEPARATION AND DEPOSITION
OF METALS (a communication to me from abroad by Bernhard Moebius of
Chihuahua, Mexico, Metallurgist) 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 a process and apparatus for refining silver and
separating it from gold, platinum, copper, lead, and other metals by means of
electricity which apparatus when slightly modified, can be used in other electro-
lytical processes for the decomposition and precipitation of metals by electricity.
Reference is to be had to the accompanying drawings forming part of this
specification in which similar letters of reference indicate corresponding parts in all
the figures.
1
Figure 1 is a front view of the improved apparatus for the electrolytical
separation and deposition of metals, parts being in section. Figure 2 is a face view
of part of the same, parts being in section and parts raised. Figure 3 is a cross
sectional elevation. Figure 4 is another cross sectional elevation. Figure 5 is a
longitudinal elevation of the frames for holding the bags showing the manner in
which the bags are held, parts being broken out and others shown in section.
Figure 6 is a perspective view of the anode and its holder. Figure 7 is a
perspective view of one of the cathodes.
In refining silver with this improved apparatus the silver to be refined is cast in
blocks or bars A. as shown in Figure 6, provided in the upper edge with threaded
apertures for receiving the ends of screws A2 which pass freely through a bar or
rod A³ having its ends bent up in the manner shown so as to adapt them to rest
upon the conductors as shown in dotted lines the bent ends of the bars or rods A³
being recessed in the bottom to receive the conductors and prevent shifting of the
bars on the said conductors. The screws A² are provided at their upper ends with
handles a, and above the bar A³ winged nuts a³; are screwed on the screws A²
whereby by turning the said nuts, the anodes A can be raised or lowered in
relation to the bar or rod A³ resting on the conductors. The lower parts of the
screws A' are plated with gold or platinum and when screwed into the upper edge
of the anode A, they may be provided with a coating of varnish to prevent their
being acted upon by the solution. The anode can have any desired shape but it is
preferred to make it in the shape of a flat rectangular block, as shown in figure 6.
The anodes A, and the cathodes B, must be held to conducting wires C. D.
respectively, and they form the elements of an electric battery, the solution of
which battery is contained in a liquid proof tank, box or tub, H, of which a series
is placed in a trough-shaped vessel H1, which is adapted to receive the liquid and

page_text: metals which are spilled by accident or otherwise. The trough-shaped vessel H¹
rests upon a suitable base H2 made of strong timbers or constructed in any other
suitable manner. The tanks H may be made of wood, earthenware, enamelled
metal, or other suitable material. In each tank or box H a frame I, is placed,
having four corner standards I, each provided in its upper end with a notch I',
adapted to receive the anode conductors C, which can be held within the notch by
a pin passed transversely through apertures in the upper part of the standard. The
standards are united near their upper ends by horizontal rods I³, provided on their
upper edges with upwardly projecting pins I placed at suitable intervals. The
said rods I³, that is, those rods parallel with the anode conductors, support frames J,
the end standards J' of which are provided at their upper ends with notches J'
adapted to receive the ends of the anode supports, the said standards being provided
at their upper ends with apertures through which pins are passed for holding the
anode supports in place.
The standards J¹ are united by two longitudinal rods J³ which rest upon the
upper edges of the rods I³ of the frames I. Each anode A is held in a frame J and
is surrounded by a bag K made of muslin or other fabric or material that will
permit the solution and current' to pass through it, through the seams of which
bag K the bars Js of the frame J are passed for the purpose of holding the bag
surrounding the frame J and the anode in the same. The frame I is surrounded
by a larger bag K₁ provided at its upper edges with rings or loops K2 through
which the pins I on the bars 13 of the frame I can be passed for the purpose of
holding the bag K¹ stretched over the frame I. This bag K¹ is also made of
muslin, canvas, or other material that will permit the solution to pass..
·
The cathodes B are suspended by means of their wires B¹ from the cathode
conductors D which run at right angles to the cathodes and parallel to the
longitudinal axis of the trough H¹. The positive or anode conductors C which rest
in the notches I² of the standards I¹ of the frames I contained in the tanks or
boxes H run parallel with the conductors D but are arranged a short distance
below the said conductors and inside of the same. The conductors D are held in
transverse bars or strips D¹ and the conductors C are held in transverse bars or
strips C; the strips D' are between the strips C¹ and the ends of the conductors D
extend beyond the bars D¹ and rest on the bars C¹. The ends of ropes or belts L
are secured to the cathode conductors D by hooks or snaps L' or in any other
suitable manner, the said belts or ropes passing through eyes L² held on at bar L³
passing longitudinally over the middle of the tanks in one section, the ends of the
said bars being suitably guided to move vertically by standards M. The bar L³ is
suspended from a beam or cylinder N by a series of chains or ropes N' having their
lower ends suitably connected with the bars L³.
The above mentioned beam shaft or roller N is journaled in the standards M and
on one end is mounted a grooved pulley O around which a driving chain or belt O
passes, which also passes over a pulley O2 pivoted on the outside of one of the
standards M the shaft of the pulley being provided with a ratchet wheel 0³ and a
crank O, the pawl 05 engaging with the ratchet wheel. Ropes or straps P which
may be provided with buckles are passed around the conductors, C. D so that when
the conductors D are raised the conductors C will be suspended from the same as
shown in Figure 4.
In electrolytical processes, that is, where metals are decomposed or separated
and deposited by electricity. the elements become polarized, which polarization is
caused by the accumulation of super-oxides or oxygen bubbles on the anodes and
hydrogen bubbles on the cathodes, and is also caused by an irregular mixture of
the solution.
This irregular mixture produces solutions of metals of different specific gravity
thereby producing several layers, each layer forming an element, the elements
consisting of one part of metal and two parts of different.fluids and these new
elements produce a secondary or polarizing current which causes a corrosion of the
cathodes and an irregular decomposition of the anodes. To prevent this polarisation

page_text: of the electrodes I have provided means for agitating the liquid and these means
consist of shovels or blades K5 hung on the conductors C and having their lower
wider ends K7 bent inward and downward. The upper end of each agitator or
shovel K³ is connected by a cord K with a frame V₁ which will be described
hereinafter. I prefer to use two agitators for each tank or box H and to arrange
them in diagonally opposite corners.
Each element that is each cathode and each anode is provided with brushes for
brushing the surface of the same and thus preventing the accumulation of metals
and per-oxides and the accumulation of bubbles of hydrogen and oxygen on the
elements, the formation of bridges or metal connections between the electrodes; and
the formation of projections on the cathodes. This permits of placing the anodes
very close to each other without any danger of their forming connections with each
other. The brushes Q2 are united in pairs the bristles or pins facing each other
and at their upper ends the brushes of one pair are united by a screw spindle R
having right and left hand threads, so that by turning the said spindle the upper
ends of the brushes may be moved towards and from each other. Preferably two
pairs of brushes are provided for each anode, and two for each cathode, so that two
brushes will be on each surface of each anode and each cathode, the brushes being
arranged as shown in Figures 3 and 4. The brushes are secured near their ends to
bars or strips S, S₁ in such a manner, that they can be shifted to be a greater or less
distance from each other on the said bars. The ends of the bars S rest in rabbets T
formed in the upper edges of the longitudinal bars of the frame V and the bars S¹
rest in rabbets T¹ formed in the inner upper edges of the longitudinal bars of the
frame V which is located below the frame V and is smaller than the same, so that
the inner edges of the longitudinal bars of the frame V will be flush with the
vertical sides or backs of the rabbets T¹ formed in the inner edge of the lower
smaller frame V¹. Ropes W, W, are passed through the eyes L² of the bar L³ and
the ends of the ropes are connected with the longitudinal bars of the upper frame. V.
Ropes or straps a which may be provided with buckles are passed around the
longitudinal bars of the frames V and V₁ or in place of straps or ropes other
adjusting devices can be used, said devices being of about the same length as the
straps P so that when the frames V are raised the frames V₁ will not be raised
with them until the said frames V are a certain distance above the frames V¹.
Horizontal bars d are held in guides d¹ on the inner surface of the upper parts of
the standards M in such a manner that the said bars can slide in the direction of
their length. The bars each have one end connected by a connecting rod c with a
worm wheel c¹ engaging with a worm c² revolved by means of suitable gearing.
On each bar & two bars f are hung, the lower ends of the bars f passing through
the vertical slots in the bars g of the frames V and V₁ and below the bottom of the
lower frame V a key h is passed through each vertical rod f on which keys h the
frames V rest. The bars are each provided with a series of apertures which
permit of holding the frames V, VI, higher or lower.
By means of the worm gearing above described the bars d are reciprocated in
the direction of their length and the bars f suspended from the bars d will be
reciprocated in the same direction as the bars & thereby reciprocating the brush
frames V and V¹ suspended from the bars f whereby the brushes are reciprocated
horizontally and parallel with the faces of the anodes and cathodes and brush the
surfaces of the anodes and cathodes thus keeping them clean.
As the frames V₁ are reciprocated in the horizontal plane they swing the
agitators K³ as the ropes or cords Ko pull on the upper ends of the agitators thereby,
swinging their lower ends upward and when the frames V₁ return, the weight of
the agitators causes them to swing down.
In case the elements are to be raised out of the tanks or boxes the shaft N is
revolved by means of the gearing above described and the ropes N¹ are wound on
the shaft and thereby the negative or cathode conductors D and the upper brush
frame V are raised. The object of this arrangement is that when the operation is
interrupted the cathodes can be raised very rapidly and are thus protected from

page_text: being acted upon or destroyed by the solution and at the same time this construc-
tion permits of immersing the electrodes as much as may be desired, whereby the
density of the current may be regulated.
When the ropes or straps a are drawn taut the positive or anode conductors C
and the brush frame V' are also raised as shown in Figure 4, the frames I, J; and
the bags K, K¹, remaining in the tanks H as shown in Figure 4 and when the pins
are passed through the apertures in the upper ends of the standards I and J¹
respectively of the frames I, J, the said frames and the bags held on the same will
also be raised with the anodes and cathodes.
The troughs H and the frames I J when made of wood are provided with several
coats of graphite paint and powdered graphite is rubbed on them for the purpose
of protecting them from being destroyed by salts and acids. By black leading the
frames J they become conductors of electricity and if a contact is made between
the notches J2 and the anode conductors the current will act on the metals brushed
from the anodes and lying on the bottom of the frame whereby remnants of peroxide
and metallic silver which may still be present are dissolved and extracted. The
sacks or bags which receive the gold, silver, etc, are saturated with a solution of
coal oil, linseed oil, and paraffine whereby they are rendered very pliable and can
resist the action of the acids and salts. Those parts of the conductors which
come in contact with the frames the tanks, etc, are provided with rubber insulators.
The operation is as follows
As stated above the base bullion to be refined is cast in the shape of suitable
blocks or plates for anodes.
As cathodes I use silver coated copper plates which give nearly the same results
as silver plates but are not as expensive as these. Pure copper cathodes are not
advisable as they destroy the exciting liquid in precipitating by simple immersion
the silver contained in the solution.
The exciting liquid employed consists of a solution of nitrate of silver, nitrate
of copper, and nitric acid and may be formed in the battery by adding diluted
nitric acid which dissolves the silver and copper contained in the bullion to be
refined. Obtaining the correct solution is accelerated by arranging the electrodes
in such a manner that the cathodes dip but slightly into the exciting liquid whereby
more silver is dissolved than is precipitated by the cathodes. The presence of
copper in the solution is necessary to ensure the precipitation of all the lead as
peroxide of lead at the anodes. Oil is rubbed on the cathodes to prevent the
adhesion of the silver. The current which must be of small electro motive force
(from one to three volts per cell) dissolves the silver and precipitates it at the
cathodes in a loose spongy state or in a crystalline shape according to the concen-
tration of the solution and the density of the current. The silver drops from the
cathodes to the bottom of the receptacles or bags K¹ in which it collects.
The copper is dissolved also but as it is less electro negative it remains in solution,
provided the exciting liquid is not too poor in silver and too rich in copper.
But even if some copper should be precipitated with the silver it would be
removed with the same from the cathodes and as it comes in contact with the
silver solution in the bottom of the receptacle it would redissolve and precipitate
its equivalent of silver. The lead as peroxide, as well as the gold, platinum,
antimony and variable quantities of peroxide of silver, are precipitated at the
anode, from which they are continually removed and are caught and retained in
the bags K surrounding the anodes.
In carrying out this operation the brushes above described are very effective as
they continually remove the silver from the cathodes and thereby prevent the
formation of bridges or metallic connections between the electrodes and avoid the
dropping of silver in the anode or gold bags K. The anodes can be placed very
near together whereby the resistance of the cell is considerably reduced.
The peroxides formed and precipitated at the anodes in the course of time forin
a thick layer on the same and as they are bad conductors of electricity and produce
secondary currents or polarization in the battery they would cause a considerable;

page_text: weakening or waste of the current if they were not removed from the anodes by
the brushes and collected in the bags provided for this purpose.
In this process I use only one exciting liquid and there is no need of a dialyser
such as a porous cell membrane, etc, to keep the exciting liquid of the anode
separated from that of the cathode. The bags above described only serve as
receptacles for the metals precipitated at the anodes and may be substituted by a
box or other receiver or receptacle placed under or around each anode. The only
object of this arrangement is to keep the anions and cations separate and not to
let them both drop to the bottom of the tank consequently it is immaterial whether
the anodes or the cathodes or both are provided with such boxes or receptacles.
For that reason I do not limit myself in this respect to any special arrangement
for carrying out the process.
The anions brushed from the anodes fall to the bottom of the frame and if a
contact of the latter with the anode supporter is established the current acts upon
the anions whereby remnants of peroxide and of metallic silver and copper which
may still be present are dissolved and extracted.
This extraction will be more effective if the exciting liquid contains a larger
quantity of nitric acid.
The antimony, lead, as peroxide of lead, and other impurities contained in the
silver remain with the gold from which they are separated by melting, and the
peroxide of lead is thus changed to oxide of lead, and all the oxidizable metals are
converted into slags thus leaving the gold separate from the rest.
But if it is desired to obtain absolutely pure gold devoid of platinum and
platinum metals which are to be separated from it, the following method may bo:
employed.
The contents of the gold bag are washed and placed in a retort containing
bromine water having a surplus of bromine.
The bromine water may advantageously contain hydro-bromic acid which is
easily obtained by exposing the bromine water to the sunlight for some time.
The retort is connected with a receiver which is filled with iron shavings and some
water; the gold, peroxides, etc, are converted into bromides, the surplus of bromine
is distilled into the receiver filled with iron, and it forms bromide of iron which is
dissolved in the water contained in the receiver.
After diluting the gold solution with cold water it is conducted from.the retort
into a tank where the gold is precipitated by the bromide of iron formed in the
receiver. The solution which still contains platinum metals etc, is then drawn off
into another tank in which plates of iron are suspended by which the platinum
metals, lead, copper, etc, are precipitated.
The separation of these metals is then continued in the well known manner.
The remaining solution is devoid of all valuable metals and is evaporated from
the salt obtained (consisting principally of perbromide of iron) and the bromide.
and hydrobromic acid employed in the process is easily regenerated by treatment
with sulphuric acid.
If the silver contains osmi-iridium, it remains with the residuum in the retort
the said residuum consisting principally of bromide of lead and bromide of silver
is reduced by contact with zinc. Bromide of zinc results and can be used for the
regeneration of bromine.
The regeneration is carried out in such a manner that the bromine and hydro-.
bromic acid is distilled directly into the retort containing the contents of the gold
bags whereby handling of the bromine and the unpleasant effects of its fumes are
avoided.
If in the course of time the exciting liquid in the battery becomes too concen-
trated and contains too much copper and not enough silver, the copper will be
precipitated with the silver and in case this occurs the solution must be regenerated
in the following manner.
After removing all the electrodes and the anode bags, copper plates or blocks are
hung in the cell whereby the silver remaining in the solution is precipitated in

page_text: a short time as the brushes continually remove the silver deposited in a loose state
on the copper plates and a clean surface of the latter is always exposed. After
having removed the bags surrounding all the electrodes with the precipitated silver
therein, the greater part of the copper in solution is precipitated by means of a
a.s anodes
current having a greater electro motive force, carbon plates being used
and copper plates as cathodes.
1
The density of the current and the nature of the exciting liquid considerably
affects the quality of the copper liberated at the cathodes and to obtain it in
a regular coherent shape it would require either a very large surface of electrodes
or a weaker current. This would make the plant larger and more expensive or
delay the precipitation too much. For that reason I prefer to use a strong current
with electrodes of ordinary size and thereby precipitate the copper in loose powder
at the cathodes.
As the carbon anode cannot be dissolved the solution becomes more and more
acid and this free nitric acid will redissolve the fine copper precipitate on the
bottom of the tank and thus frustrate the entire operation.
To prevent this I place a large copper plate or bar under each electrode and on
the bottom of the tank and by means of wires bring it into contact with the
cathode conductors, whereby the precipitated copper drops upon this plate and
forms a part of the cathode, increasing its surface and preventing the redissolving
of the copper.
The brushes above referred to are also of great service during this operation as
they remove the bubbles of hydrogen and oxygen that accumulate on the electrodes
and prevent polarization and the consequent waste of power.
It would be advisable to use an anode bag in this case also in order to prevent
the hydrogen bubbles arising from the the plate below the electrodes from mixing
with the oxygen bubbles at the anodes.
The solution remaining in the bath and now containing much free nitric acid is
used in the process again partly for replacing the water evaporated from the tanks
and keeping the exciting liquid sufficiently acidulated and partly for making a
new solution by mixing it with the solution that already contains enough silver.
.
If the copper in the alloy amounts to about one third of the silver the nitrate of
silver in the exciting liquid will be converted into nitrate of copper too rapidly
and then the separation of the silver from the copper, gold, etc, in one operation is
no longer practicable. The following preliminary treatment must then be employed
for first extracting the copper from the alloy.
The exciting liquid used in this case consists of an acidulated solution of nitrate
of copper. In place of this, sulphate of copper may be used when the alloy is poor
in silver.
The anodes are formed of blocks or plates of the alloy and the cathodes of
copper plates. The electric current which must be of small electro motive force
dissolves the copper and precipitates it at the cathodes the silver, gold, platinum,
lead, etc, remaining at the anodes in a more or less coherent state according to the
composition of the alloy.
The silver accumulating at the anodes will finally precipitate to such an extent
that it would go into solution also and be precipitated with the copper if it were
not continually removed together with the gold and silver from the anodes by the
brushes and thus withdrawn from the dissolving action of the current.
The silver, gold, platinum, etc, gathered in the bags are melted and cast into
plates or blocks to be used as anodes and the metals are then separated as herein-
before described.
The principal advantages of this improved process are as follows:-The operation
is continuous and very simple, a large quantity of silver can be refined very.
rapidly and at a very low cost, as the quantity of chemicals required is com-
paratively, small, there is no need of filtering and transferring or handling acids
producing noxious or dangerous fumes, the gold and silver obtained are very pure;
:

page_text: all the platinum metals contained in the gold and silver can be recovered and
copper is obtained as pure metallic copper.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I'claim is
זי זי
9
:)
1st In an apparatus for refining silver the combination with an anode formed, of
the silver to be refined of a cathode provided with a coating of silver substantially
herein shown and described.
as
2. In an apparatus for, refining silver the combination with a cathode provided
with a coating of silver, of an anode formed of the silver, to be refined and
surrounded by a bag substantially as herein shown and described.
3. In an apparatus for separating metals by electrolysis, the combination of a
cell and a series of elements therein, of a bag surrounding the elements, and means
for raising said bag out of the exciting, liquid, substantially as herein shown and
described.
I
4. The combination with a cell and electrodes, of brushes or scrapers contained
within the cell, means for moving the brushes or scrapers along the surface of the
électrodes, and means for adjusting the brushes or scrapers to suit the different
thicknesses or positions of electrodes, substantially as herein shown and described.
5. The combination with a cell and electrodes or elements in the same, of
scrapers for acting within the cell and exciting liquid on the surfaces of the
electrodes, means for removing the electrodes and the brushes adapted to act on
the same from the cell at the same time, substantially as herein shown and
described.
6. The combination with a cell and two sets of electrodes or elements in the
same, of reciprocating brushes or scrapers for acting on the electrodes within the
cell and the exciting liquid, of separate devices for operating the brushes or,
scrapers for each set of electrodes, and means for removing each set of electrodes
independently one after the other and at the same time removing the corresponding
brushes or scrapers, substantially as herein shown and described:
7. The combination with a cell, of anodes and cathodes, a bag surrounding all
the anodes and cathodes in one cell, and means for raising the anodes, cathodes, and
bags together, substantially as herein shown and described.
8. In an apparatus for the separation of metals by electrolysis, the combination
with a reciprocating frame, of pivoted agitators having their upper ends connected
to said frame and operated thereby, substantially as herein shown and described.
9. The herein described anode supporter consisting of a bar through which
screws are passed, on which screws locking nuts are mounted above the bar, the
lower ends of the said screws being adapted to be held to turn in the top edges of
the anodes, substantially as herein shown and described.
10. In an apparatus for the separation of metals by electrolysis, the combination
with a cell and its anodes and cathodes, of a bag surrounding each anode, and a
bag surrounding all the anodes and cathodes, substantially as herein shown and
described.
11. The herein described method of refining silver by electrolysis, consisting in
subjecting the alloy as anode to an electric current of small electro motive force in
a bath consisting of nitrate of silver, nitrate of copper, and nitric acid, and pre-
cipitating the silver at the cathodes in a loose spongy or crystalline state, leaving
the copper in solution and metallic gold, platinum, antimony, and all lead as
peroxide of lead at the anode and preventing the anions and cations from being
mixed with each other by receptacles placed under or around the electrodes,
substantially as described.
12. The herein described method of refining silver by electrolysis which consists
in subjecting the alloy as anode to an electric current in a bath of nitrate of silver,
nitrate of copper, and nitric acid and precipitating the silver at the cathodes
leaving the copper in solution and gold, platinum, lead, etc, at the anode and

page_text: .
subjecting the electrodes to a continuous brushing or scraping, whereby anions and
cations are removed from the same and a complete separation of the metals is
effected; substantially as set forth.
13. The herein described method of refining base bullion, that contains more
than about one third of copper, which consists in subjecting the alloy as anode to
an electric current in a bath of nitrate or sulphate of copper and precipitating the
copper at the cathodes leaving the gold, silver, lead, etc, at the anodes and
subjecting the same during the action of the current to a continuous brushing or
scraping whereby the silver, gold, lead, etc, is removed from the anodes and
dissolving action of the current, whereby a simultaneous précipitation of silver with
the copper is prevented and the decomposition of the alloy greatly accelerated,
substantially as herein shown and described.
14. The herein described method of facilitating and accelerating the precipitation
of metals in solution by immersion of a precipitant metal, which method consists in
subjecting the precipitant metal to a continuous scraping of brushes or scrapers
acting on the said precipitant metal during the time the same is in the solution
substantially as herein shown and described.
15. The herein described method of separating the gold from mixtures of metals,
which consists in dissolving the gold in a closed vessel by a solution of bromine
and hydrobromic acid and distilling the surplus of bromine in a receiver filled with
iron shavings, whereby bromide of iron is formed that can be used for precipitating
the gold in the solution drawn from the vessel, substantially as herein shown and
described and whereby also handling of liquids producing noxious gases is avoided
and the bromide and hydrobromic acid can be regenerated with facility, as set
forth..
16. The herein' described method of precipitating copper or other metals in a
loose state by an electric current at the cathodes which consists in using an indis-
solvable metal or carbon as anode and catching the metal dropping from the
cathodes on or in a conductive plate or box placed under the electrodes and
connected with the cathode conductors, whereby a redissolving of the precipitated
metal in the exciting liquid is prevented substantially as berein shown and
described.