Improvements in the Electrolytical Treatment of Ores and Slimes for the Recovery of Precious Metals therefrom, and Apparatus therefor.
Year: 1898

page_text: PROVISIONAL SPECIFICATION,
Improvements in the Electrolytical Treatment of Ores and Slimes
for the Recovery of Precious Metals therefrom, and Apparatus
therefor.
I, HUGO RIECKEN, of 9 and 11, Worship Street, in the County of London, Assayer,
do hereby declare the nature of this invention to be as follows:-
This invention relates to the electrolytical treatment of ores and slimes for the
recovery of precious metals (chiefly gold) therefrom and to apparatus therefor, and
has for its object to effect in one operation the solution of the gold from the ore
and its deposition upon mercury in an easily recoverable condition.
The process is applicable for the treatment of any auriferous ore but is especially
valuable for the treatment of slimy and clayey ores, the nature of which is such as
to render percolation through them practically impossible.
Various electrolytical systems or methods have been heretofore tried in which
the auriferous slimes mixed with a suitable electrolyte have been subjected to
agitation in a vessel provided with electrodes. These methods have involved
the use of rotary stirrers consisting usually of carbon rods constituting the anode,
the cathode being of mercury which lies in a more or less quiescent state at the
bottom of the vessel. Such methods are however objectionable because the surface
of the mercury cathode is necessarily very limited in area, and its /action is
moreover greatly interfered with by the insulating effect of the layer of the
heavier particles of ore which inevitably settle upon it.
In order to effect a rapid and complete precipitation of the gold upon the
mercury cathode it is necessary, 1st. That the surface of the mercury should be
constantly renewed, 2nd. That it should be as large as possible, and 3rd. That it
should be so disposed that the ore does not settle upon it.
If these conditions are not observed, the gold will be precipitated in a pulveru-
lent and loosely adherent state and will be easily scoured off by the movement of
the ore and only a partial extraction and recovery of the gold will result. By the
present invention these essential conditions to a high efficiency of extraction are
ensured. The electrolyte may be cyanide of potassium, chloride or bromide of
sodium in solution jointly or separately, or other similar salt.
For the purposes of my invention I employ an open vat having a semi-circular
or angular or other suitably shaped bottom and vertical or inclined sides, and lined
with copper or other suitable metal which may or may not be silver plated. At
the lowest point of the lining is a groove for the reception of mercury, and near
the upper edge of the lining is a gutter or trough extending wholly or partially
around the lining and having holes or notches or a continuous slit in its sides or
bottom. The mercury is continuously withdrawn from the bottom of the vessel
through a tap and is raised by a pump or otherwise and delivered into the gutter
or trough aforesaid whence it escapes through the slit, holes or notches, and flows
in thin streams down the lining of the tank into the groove again at the bottom,

page_text: a continuous circulation of mercury and a clean continuously changing cathode
surface being thus maintained.
The anodes are rods or plates of carbon or other suitable metal or material fixed
to a shaft which traverses the vat and which is rotated or oscillated by any suitable
means to agitate the ore. If the shaft passes through the wall of the vat, stuffing-
boxes are provided to prevent leakage: It may be properly insulated to protect
it from electrolytic action, and is connected to the positive pole of a dynamo or
other source of electricity, the lining of the vat being connected to the negative
pole of said source.
The slimy ores may be first mixed to a pulp of suitable consistency and then
introduced into the vat, or they may be introduced gradually into a suitable
electrolyte, for instance a weak solution of cyanide of potassium to which, may be
added a salt which under electrolysis yields oxygen or an equivalent oxydizing
agent to accelerate the solution of the gold. The öre is kept agitated by the stirrers
aforesaid and a current of electricity is passed through the vat. The anion which
is generated at the anodes gradually dissolves the gold which together with the
potassium or sodium is deposited upon the cathode and both amalgamate with the
mercury. This amalgam of the alkaline metal greatly facilitates the deposition
and amalgamation of the gold. Any coarse particles of gold present in the ore
are of course immediately amalgamated. If chloride of sodium is used as an
electrolyte the sodium amalgam and the mercury may be conducted through the
tap below into a suitable receptacle containing water, the sodium being thereby
decomposed and caustic soda formed.
When it is desired to empty the vat, a manhole provided for that purpose is
opened, and the finer slimes are allowed to run out and settle. The coarser particles
in which will be found some of the gold amalgam may then be separated on con-
centrating tables or otherwise, and the amalgam treated in the ordinary manner.
By far the largest quantity of gold will be found deposited upon the sides of the
vat, and the amalgam can from time to time be scraped off in the usual manner.
The apparatus can be made of any desired capacity and can be constructed to
take very large charges of ore. I sometimes provide two or more systems of
agitators in one apparatus.
تيخي
1 1000
GEORGE HARRISON,
35, Therapia Road, Honor Oak, London, S.E.,
Agent for the Applicant.
Improvements in the Electrolytical Treatment of Ores and Slimes
for the Recovery of Precious Metals therefrom, and Apparatus
therefor.
I, HUGO RIECKEN, of 9 and 11, Worship Street, in the County of London, Assayer,
do hereby declare the nature of this invention and in what manner the same is
to be performed, to be particularly described and ascertained in and by the follow-
ing statement:-
This invention relates to a method of and apparatus for the treatment by
electrolysis of ores and slimes for the extraction of precious metals, particularly
gold, therefrom, whereby the solution of the precious metal from the ore, and its
deposition by the aid of mercury in a novel manner and in an easily recoverable
condition is rapidly effected in one, operation.
The process is applicable for the treatment of any auriferous ore but it is

page_text: especially valuable in the case of slimy, and clayey ores which are unsuitable for
treatment by the ordinary methods because percolation through them is practically
impossible.
Various electrolytical systems or methods have been heretofore tried in which
auriferous slimes mixed with a suitable electrolyte have been subjected to agita-
tion in a vessel provided with electrodes. In some of these methods rotary anode
stirrers have been employed, and a cathode of mercury which lies in a more or less
quiescent state at the bottom of the vessel. Such methods are however objection-
able because the surface of the mercury cathode is necessarily very limited in area,
and its action is moreover greatly interfered with by the insulating effect of the
heavier particles of ore which inevitably settle upon it, the mercury being active
only when for the moment the overlying body of ore is removed by mechanical
means.
In order to effect a rapid and complete precipitation of the gold upon a mercury
cathode, it is necessary; 1st. That the surface of the mercury should be frequently
renewed; 2nd. That it should be as large as possible, and 3rd. That it should be
so disposed as to avoid the settlement of ore upon it. If these conditions are not
observed, the action is slow, and the gold is precipitated in a pulverulent and
loosely adherent form, and is easily scoured off again by the movement of the
ore and re-dissolved, so that only a partial extraction results. By my invention
I secure the aforesaid essential conditions to a high efficiency of extraction by
providing a flowing stream of mercury in contact with the cathode surface as
hereinafter described. The electrolyte may be cyanide of potassium, chloride or
bromide of sodium, jointly or separately, or other suitable salt.
For the purposes of my invention I employ an open vat, made of wood for
example, and lined at the sides and if desired at the bottom with sheet copper or
other suitable metal which may be silver plated; I may also line the ends of the
vat, but this is not necessary. When the bottom is not lined with metal, it may
be coated with cement or other suitable material. The sides may be vertical, but
I prefer them to be inclined so that the mercury will remain in contact therewith
when flowing down them. At the lowest point of the lining is a gutter for the
collection of the mercury, and near the upper edge of the lining is another
suitably. constructed gutter or trough or other device such as a perforated pipe
for discharging mercury down the sides of the lining. If perforated pipes be
employed, these may be made to move in such a manner as to effect an even
distribution of mercury over the plates. The mercury is continuously or from
time to time withdrawn from the bottom of the vessel through a tap and is raised
by hand or by a pump or otherwise and delivered into the gutter or trough or
other device aforesaid near the upper edge of the lining whence it escapes and
descends in a thin stream or sheet down the lining of the tank and collects in the
gutter again at the bottom. A circulation of the mercury and a large and clean
continuously changing surface is thus maintained. The action of this large clean
surface of mercury is to cause a rapid deposition of the gold in a firm and tenacious
form upon the metal surface over which the mercury flows.. The action is
moreover, owing to the low resistance, effected with a minimum amount of
current.
The anodes are rods or plates of carbon or other suitable metal or material fixed
to a shaft which traverses the vat and which is rotated or oscillated by any suitable
means to agitate the ore. It is connected, to the positive pole of a dynamo or
other source of electricity, the lining of the vat being connected to the negative
pole of said source. In some instances the ore or slimes may be agitated or
circulated by pumps or other means, in which case the anodes may be stationary.
Referring to the accompanying drawings,
· Figure 1 is a central longitudinal section, and
Figure 2 is a central transverse section, illustrating one form of apparatus with
rotary anodes for carrying out my invention.
Figure 3 is a transverse section on the line 3, 3 of Figure 4, and

page_text: Figure 4 is a longitudinal section on the line 4, 4, of Figure 3 illustrating a
modified form of apparatus with oscillatory anodes, and
Figure 5 is a transverse section of another modification.
Referring to Figures 1 and 2, A is a tank or vat having a metal lining B the
sides of which are inclined and the bottom of which is curved. The ends of the
lining may be bent or flanged and suitably secured to the ends of the vat to
prevent leakage. In the bottom of the lining is a longitudinal groove or gutter
and near the top of the lining is a trough or gutter C having a longitudinal narrow
slit c adjacent to the metal lining. The gutter C may if desired be continuous all
round the vat. The mercury which is withdrawn continuously or from time to
time from the gutter 6 through the tap I) is collected in a receptacle E, and is
thence transferred as required by hand or by a pump F or otherwise and delivered
into the gutter C whence it flows through the slit è down the sides of the lining
in thin streams and collects again in the gutter b.
The anodes are formed by rods G of carbon or other suitable material projecting
radially from a shaft H which turns in bearings h, "h, and is rotated through a
driving pulley S or otherwise. J is a stuffing-box to prevent leakage of the
electrolyte and slimes through the end of the vat. In some instances the driving
apparatus is contained wholly within the vat, in which case the shaft does not
extend through the end of the vat, and the stuffing-box is dispensed with. The
part of the shaft H within the vat may be properly insulated to protect it from
electrolytic action and it is connected as before stated to the positive pole of a
dynamo or other source of electricity, the lining of the vat being connected to the
negative pole of said source.
The slimy ores may be mixed to a pulp of suitable consistency and then intro-
duced into the vat, or they may be introduced gradually into the vat without being
first mixed to a pulp. The vat contains a suitable electrolyte, for instance a weak
solution of cyanide of potassium to which may be added a salt capable under
electrolysis of yielding oxygen or an equivalent oxydizing agent to accelerate the
solution of the gold. The ore is kept agitated by the anode stirrers G, and a
current of electricity of suitable strength is continuously or intermittently passed
through the vat, while the mercury is kept in circulation as above stated. The
-gold is gradually dissolved and is deposited as a hard adherent amalgam upon the
metal lining B over which the mercury is flowing. An alkaline amalgam is also
formed which greatly facilitates the deposition and amalgamation of the gold.
If the gold in the ore is in a finely divided state, and soluble in the electrolyte
without the aid of electrolysis, its solution will be greatly accelerated by the agita-
tion produced by the stirrers, the current then serving to precipitate the dissolved
gold, which is accomplished in a comparatively short space of time due to the
large surface of cathode employed. Any coarse particles of gold in the ore are
of course amalgamated by the mercury.
When it is desired to empty the vat, a manhole K is opened, and the finer
slimes are allowed to run out and settle. The coarser particles among which will
be found some of the gold amalgam may then be separated on concentrating tables
The hard
or otherwise, and the amalgam treated in the ordinary manner.
amalgam of gold deposited upon the sides of the vat can from time to time be
scraped off as from ordinary amalgamating tables and treated in the usual manner
in a retort.
The vat may without difficulty be constructed to take very large charges
of ore.
In Figures 3 and 4 I have shown a form of apparatus having oscillatory stirrers,
and in this case the lining of the vat is much shallower than in Figure 1, and
approximately semi-cylindrical in shape. I have shown two sets of anode stirrers
each composed of V-shaped arms G fixed on shafts g and g¹ respectively and so
arranged that the arms of one set pass between those of the other. The shafts g
and g¹ are geared together by toothed pinions g², g2 so as to rock in unison, and
they may be oscillated by any suitable means, for instance, by a crank arm L

page_text: connected by a link L' to the pin of the crank disc which is rotated through a
driving pulley . The construction is otherwise similar to that illustrated in
Figures 1 and 2 and need not be further described. In Figure 5 the vat is similar
to that shown in Figures 3 and 4 but the anodes G in this case are fixed to a
rotary shaft in lieu of an oscillatory one.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. In an electrolytical process of treating ores and slimes for the extraction of
precious metals, particularly gold, therefrom the employment of a vertical or
inclined metallic cathode down which a stream of mercury is caused to flow,
substantially as, and for the purposes, specified.
2. A process of extracting precious metals from ores or slimes which consists
in agitating a mixture of the ores or slimes and an electrolyte in the presence of
an anode and of a cathode consisting of an amalgamating plate over which a
stream of mercury is caused to flow and passing a current of electricity through
the mixture, all substantially as described.
3. In a process of extracting precious metals from ores or slimes by deposition
of the same in an adherent form upon a vertical or inclined cathode, the use of a
stream of mercury delivered over such cathode substantially as, and for the
purposes, herein before described.
4. In the said process collecting the descending mercury and re-conveying it to
the top of the metallic cathode so as to provide a continuously renewed large clean
surface to act upon the precious metal, substantially as described.
5. An electrolytic apparatus for extracting precious metals from ores and slimes
by the process herein before described and claimed which apparatus comprises an
open tank or vessel adapted to receive the ore to be treated having an inner
metallic surface forming the cathode, a trough or gutter or other means near the
upper edge of the vessel capable of discharging mercury in thin streams or sheets
down the sides of the vessel, and an anode within the vessel, substantially as
described.
6. Apparatus constructed substantially as described with reference to one or
other of the forms illustrated in the accompanying drawings, for the purposes
specified.
1000
GEORGE HARRISON,
35, Therapia Road, Honor Oak, London, S.E.,
Agent for the Applicant.