Improved Process and Apparatus for Treating Ores and Liquors Containing Gold or Silver or both.
Year: 1895

page_text: Date of Application, 21st June, 1895
Complete Specification Left, 18th Mar., 1896-Accepted, 18th Apr., 1896
PROVISIONAL SPECIFICATION.
Improved Process and Apparatus for Treating Ores and Liquors
Containing Gold or Silver or both.
I ALEXANDER DE COURCY SCOTT of 86 Cornwall Gardens Queen's Gate in
the County of London Major General do hereby declare the nature of this
invention to be as follows :-
My invention relates to an improved process for treating masses of crushed ore
or the like and liquors and especially ores in the condition of slimes with a view of
obtaining the precious metal or metals contained therein and to improved apparatus
for carrying my said invention into effect.
According to my invention I treat the ores and liquors containing the precious
metal with the water or the solutions required under pressure so that the said
water or solutions furnish the motive power necessary for the agitation of the
particles of ore and effects the complete circulation of the same. During the
process I allow periods of rest from agitation in order to limit the consumption of
the liquids and give time for the proper action of the leaching solutions occluded in
the mass of crushed ore by its subsidence.
In apparatus constructed according to my invention for carrying out this process
I make use of a pair of vats or pairs of vats preferably in the shape of hollow
truncated cones the smaller ends thereof being situated downwardly. The said
vats communicate with each other by pairs of pipes each pipe opening at its lower
end into or towards the bottom of a vat and at its upper end into the upper part of
an adjacent vat. Opposite to and extending towards or into the lower ends of the
said pipes which are formed conical for the purpose are injector devices attached
to pipes passing out of the vats and connected with a main which is placed in
communication with tanks supplying the water or solution by means of branch pipes
provided with stop cocks or valves or the like. The ores to be treated are placed
in one of a pair of vats and the water or solution is supplied under pressure to the
injector of the said vat the liquid issuing therefrom mingles with and draws in the
surrounding ore driving it up the pipe opposite to which it is situated and delivering
it into the upper part of the adjacent vat where the process may be repeated and
the liquid mass again transferred into the first vat thus producing a complete
circulation of the slimes and their intimate mixture with the liquids used. The
pressure required for the liquid for treating the ore may be obtained by supplying the
liquid to the vats from elevated storage tanks such tanks being filled with the liquids
by pumping or partly by pumping and partly by causing water to gravitate to the
tanks from a higher source (if such be available) or the liquids may be directly
supplied to the tanks under pressure by pumping or by means of compressed air or
any other suitable means.
I prefer to employ the storage tanks in pairs (or sets) for the liquids according
to the amount of precious metal which they have been caused to take up one tank
of a pair being situated at a low level and the other at a high level the said liquid
which is drawn from time to time from the vats as hereinafter described being
allowed to gravitate to a special low level tank and thence pumped if so required
to the corresponding high level tank thence flowing under pressure to the vat
containing the ore.

page_text: The following example illustrates the manner in which my invention is carried
into effect, when treating ore of such a nature that it is necessary :-
(1) To wash the ore with water.
(2) To wash it with an alkaline solution.
(3) To leach it with a solution of potassium cyanide aud
(4) To wash the ore with water to extract occluded cyanide of gold, but I do
not limit myself to the precise details.
Crushed ore whether in the form of slimes or of a mixture of slimes and larger
particles is placed in one of a pair of vats, water is then admitted to the injector in
the said vat from an elevated water tank and the jet passing into the base of the
hollow cone flows up the pipe leading to the second or adjacent vat, carrying with
it the crushed ore, so that a stream consisting of an intimate mixture of water and
crushed ore pásses into the said vat.
As soon as the transfer of ore from the first to the second vat has been completed,
the flow of water is cut off, the particles of ore are allowed to subside and when
the subsidence is completed the supernatant water is withdrawn for example by a
syphon or by opening suitably placed apertures in the vat above the subsided ore.
The alkaline solution stored in an elevated tank is then admitted to the injector
in the second vat and the which is settled therein is carried into the first vat by the
stream issuing from the injector. The separation of the ore and alkaline solution
then takes place by subsidence of the former and the spent alkaline solution is
withdrawn and run to waste.
A solution of cyanide of potassium is then admitted to the injector in the first
vat and the transfer of the ore to the second vat is effected. The supernatant
liquid now consists of a mixture of solutions of cyanide of potassium and cyanide of
gold; if the amount of gold in solution is found to be not sufficient to enable the
liquid to be economically treated for the precipitation of gold, the supernatant liquid
is withdrawn and pumped up into an elevated tank where it is left undisturbed for
a certain period of time. After a suitable interval the solution is again admitted
to the injector in the second vat and the partially leached ore is again transferred
by the stream from the injector to the first vat; if it be found that the supernatant
liquid contains a sufficient quantity of gold in solution to render the liquid suitable
for economical precipitation, it is transferred to any suitable apparatus used for this
purpose and treated accordingly. In the alternative the transfer of the supernatant
liquid to another low level tank and thence by pumping to another elevated tank
would follow and another transfer and leaching of the ore would take place.
After the treatment with cyanide solution is completed, water is admitted to the
injector in the first vat and the crushed ore is washed by transfer to the second vat
in order to obtain the occluded cyanide of gold. If the resulting supernatant liquid
be weak in gold for treatment by precipitation it is transferred to one of the stored
tanks containing the cyanide solution in the usual manner being first reinforced by
addition of cyanide of potassium if required.
Finally the pipe leading from the second vat to the first vat is disconnected from
the injector device and water is admitted to the injector in the second vat for the
purpose of discharging the spent ore either into trucks or into a launder for
conveyance to the waste heap.
The treatment of ores so far as relates to the strength, number and nature of the
solutions used and the order in which they are used will of course vary according to
their particular character but the essential features of the invention will in all
cases remain unchanged.
Dated this 21st day of June 1895.
JOHNSONS & WILLCOX,
Agents.

page_text: Improved Process and Apparatus for Treating Ores and Liquors
Containing Gold or Silver or both.
I, ALEXANDER DE COURCY SCOTT of 86 Cornwall Gardens, Queen's Gate, in
the County of London, Major General, do hereby declare the nature of this
invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement:-
My invention relates to an improved process for treating masses of crushed ore
or the like and liquors and especially ores in the condition of slimes with a view of
obtaining the precious metal or metals contained therein and to improved apparatus
for carrying my said invention into effect.
According to my invention I treat the ores and liquors containing the precious
metal, with the water or the solutions required under pressure so that the said
water or solutions furnish the motive power necessary for the agitation of the
particles of ore and effect the complete circulation of the same. During the
process I allow periods of rest from agitation in order to limit the consumption of
the liquids and give time for the proper action of the leaching solutions occluded
in the mass of crushed ore by its subsidence and I take advantage of the subsidence
of the ore in order to remove the supernatant liquids by decantation with a view to
their further use before or after treatment for the extraction of gold or silver which
they may contain.
I will describe my invention with reference to the accompanying drawings, in
which
Figures 1 and 2 illustrate in side elevation and plan respectively, both partly
in section a pair of vats and parts connected therewith constructed according to
my invention,
Figure 3 shews in plan an arrangement of vats and supply tanks with their con-
nections for treating a supply of ore and liquor containing the precious metal
according to my invention and
Figure 4 is a plan of a modified arrangement.
Referring first to Figures 1 and 2 A and A' are a pair of vats shaped preferably
as shewn in Figure 1 cylindrical at the upper parts and formed at the lower part in
the shape of a truncated cone, the upper and lower edges of which are curved off
as shown. The said vats A and A¹ communicate with each other by pipes B B¹
each pipe opening at its lower end towards the bottom of the vat and at its upper
end into the upper part of the adjoining vat. Opposite to the lower ends of the
pipes B B¹ are injector nozzles c c attached to supply pipes C C¹ leading outside
the vats and connected with mains d¹ d² d³ d on either side leading from tanks
which contain the solutions or water for treating the ores in the vats A A'.
Branches from the mains are provided with stop valves e for controlling the flow
of liquid from any required tank to the vat and reflux valves for preventing the
liquor supplied from one tank flowing into the back portion of the supply pipe.
I preferably discharge the exhausted ore and contained liquor by means of a second
set of injector nozzles Cx and C₁x and pipes B and B discharging into a
launder N for conveyance to any selected locality. The injectors cx and cx are
supplied with water by pipes Cx and C¹× on which stop cocks are placed so that
water can be supplied to and cut off from each injector in turn. If the supply of
water available is too small to admit of the use of an injector for discharging the
spent ore the ore may be discharged in the ordinary way through apertures formed
in the sides of the vats or in the bottom thereof into shoots leading to trucks for
conveyance to the waste heap. The apertures (when employed) must be provided
with gates or covers of any known type for closing the same when out of use.

page_text: The vats are provided with overflow pipes or syphons or like means for drawing
off the liquor therefrom.
I preferably employ wrought iron or steel pipes g g¹ attached to floats
provided with roses at their upper ends and jointed to fixed pipes jjj¹¹at their
lower ends. The pipes jjjj pass through the sides of the vats A and A' the
outer ends of the two inner pipes being provided with screw threads and unions by
means of which a suitable length of flexible hose pipe b may be attached as
required. The other end of such flexible hose pipe can be attached at will by
means of unions to any one of the pipes, I m or 1. Each branch of the said
pipes m or is provided with a stop valve of any suitable kind as shewn. The
two outer pipes jj are continued beyond the point at which they issue from the
vat A or A¹ to the pipes (k or k¹) which latter lead to a receiver.
The vats may be mounted in any suitable manner a convenient method being
to set them in masonry piers such as O a passage o being provided as a means of
access to the lower portion of the vat. Platforms P are provided at the sides of
the vats on which are rails for running trucks to the said vats for feeding the same
with the material from which the precious metal is to be extracted and there is a
central platform P¹ for use as a gangway. The ores to be treated are fed from
the trucks into one of the vats, for example into the vat A, and water or solution
is supplied under pressure from the supply pipe C to the injector nozzle c; the
liquid issuing therefrom mingles with and draws in the surrounding ore driving it
up the pipe B and delivering it into the upper part of the adjacent vat A¹ where
after settlement of the ore and withdrawal of the supernatant liquid the process
may be repeated and the ore together with the injected liquid again transferred by
the pipe B into the first vat A. The slimes when sufficiently exhausted of their
precious metal are removed by means of the injectors c* cx and the discharge
pipes B and B to the launder N or through apertures in the sides or bottoms
of the vats as already described. The liquid containing the precious metal in
solution is run off after subsidence of the slimes from the vat to storage tanks
where it is treated directly for gold or stored for re-use as hereinafter described.
The treatment of an ore will be modified according to its particular character
but the two examples which I will now describe will illustrate the manner in which
the vats constructed according to my invention may be put into practical use but it
will be understood that I do not limit myself to the precise details described.
Figure 3 illustrates in plan one arrangement in which the character of the
ground is such as to permit of the tanks containing the liquors for treating the
ores being situated in an elevated position above the vats so that the liquids will
feed from these tanks at a pressure sufficient to effect the proper working of the
plant.
I will assume that in this example that the ore in the form of slimes taken from
a stock dumped near the mill site, is of such a character that it requires to be
treated first with an alkaline wash, second with a strong solution of potassium
cyanide and thirdly with a weak solution of potassium cyanide.
I will also assume that in this example the decanted liquors resulting from the
use of the solutions of cyanide of potassium on one charge of ore are not strong
enough in precious metal for the precipitation process by which such metals are
usually extracted.
A A' are the vats arranged in pairs in any desired number according to the
amount of ore to be treated. Q indicates a pumping engine working one or more
force pumps and feeding liquors alternatively or simultaneously as may be desired
by two pipes q g' from the tanks R1 R2 R to tanks S¹ S² S³ S. The tank R¹ is
intended to contain the strong solution of potassium cyanide, the tank R2 the weak
solution of potassium cyanide and the tank R* water-the tank S receives the
strong solution of cyanide from the tank R¹, the tank S2 the weak solution of
cyanide from the tank R2 while water is supplied to the tank S³ or to the tank S
in which former tank (S³) it is mixed with a suitable alkali or alkaline earth to form

page_text: the alkaline solution. Each of the pipes d¹ d² d³ or d communicates with the
corresponding tank S1, S2, S³ or S* containing a liquor as specified and so conveys
the liquor to the injectors c c¹ fitted to each of vats A A¹ of the series. The
three lines of pipes and m running between the rows of vats A A' and the two
lines of pipes kk' outside the vats A A¹ I have already described with reference
to Figure 1.
I
The pipe conveys to the tank R¹ the spent strong cyanide solution drawn off
after use but which is too weak in gold or silver or both for economical precipita-
tion. The pipe in like manner conveys the weak solution after use to the tank R2
while the pipe m conveys the sufficiently concentrated solution of cyanide of gold
to a gold solution tank T placed at the head of the precipitating house U. The
pipet conveys the spent gold solution after treatment for the recovery of the gold
in the precipitating house back to the cyanide solution tank R2 for reuse, after it
has been reinforced with potassium cyanide or it might be conveyed to the tank R¹..
For this reuse it is pumped back to the tank S' or S2 and a complete circulation of
the liquors is thus obtained. The pipes placed on either side of the vats
convey away the spent alkaline solution to a reservoir or the like for storage
whence it may be led by a suitable pipe to the pump Q and be repumped to the
tank S³.
The method of treating the slimes in this apparatus is as follows:-
A vat A is first charged with slimes from a truck on the platform, sufficient
being admitted to cover the injector nozzle c and the orifice of the pipe B; the
alkaline solution from the tank S³ is then admitted through the injector nozzle by
the pipe d³ and the charging of the slimes from the truck to the vat is continued
simultaneously. The slimes intimately mixed with the liquor will be injected
through the pipe B into the vat A' the process of feeding into the vat A being
completed when the vat A' is full. The slimes are then allowed to subside and the
decantation effected the spent liquor being conveyed by the pipe k¹ to a reservoir
whence the said liquors may be forced by the pump back to the tank S³ for reuse..
The slimes are next treated with the strong solution of cyanide of potassium which
is admitted to the vat A¹ by the pipe d' from the tank S₁ so that the slimes and
solution pass back to the vat A.
Subsidence then follows and decantation of the liquor by the pipe to the storage-
tank R¹ where it becomes part of the common stock which is maintained at standard
strength in cyanide and is pumped to the corresponding tank S' and thence admitted
again into ore contained in the vats. The weak solution of cyanide is then.
admitted from the tank S2 by the pipe d² to the vat A. a transfer of the slimes and
solution from the vat A to the vai A' again takes place followed by subsidence-
and decantation of the spent solution which is in turn transferred by the pipe l¹ to
the storage tank R2. Here it becomes a part of the common stock of weak solution.
of cyanide which is maintained at standard strength.
When the liquid contains sufficient precious metal in solution it is drawn off from
the vat it occupies by the pipe m which conducts it direct to the tank T. After-
treatment for the recovery of the gold (or silver) the spent cyanide solution is
conveyed for reuse to the tank R' by the pipe t as already described.
I have assumed in this case that the charge of ore will be sufficiently exhausted
of the precious metals after treatment with strong and again with weak cyanide
solution.
Finally the ore is discharged into the trough or launder N for conveyance to the
waste heap by the injector c* or c¹* and discharge pipes B* or B or otherwise as
already described. The vats are worked in pairs and I may have as many pairs
working in a plant as may be found convenient.
In the arrangement shewn in plan in Figure 4 the pump Qforces the liquors
into the accumulators S1 S2 S3 S which are substituted for the high level tanks it
being assumed in this case that there is no elevated ground conveniently situated
on which to place the high level tanks containing the liquids as shewn in Figure 3.
The accumulators are fitted with loaded rams and provided with suitable inlet and.

page_text: outlet pipes and valves through which liquid is driven by pumps so as to obtain the
pressure necessary for supplying the injectors.
Water is pumped into the accumulator S and alkaline solution into accumu-
lator S³ the stronger cyanide solution into the accumulator S₁ and the weaker
cyanide solution into the accumulator S2. The pipes delivering these liquids into
the accumulators are lettered $ 83 83 8' respectively.
The pipes d' convey water, the pipes d³ alkaline solution the pipes d' the stronger
cyanide solution and the pipes d² the weaker cyanide solution to the vats A A' as
already explained.
The pipes and m in Figure 4 perform the same functions as the corre-
spondingly lettered pipes in Figure 3. In like manner R¹ is the stronger solution
cyanide tank, R² the weaker solution cyanide tank, R³ the alkaline solution
tank, R the water tank, T the gold solution tank and U the precipitation house.
I preferably employ a separate pump for each accumulator. The materials are
treated with the liquors for obtaining the precious metal in this arrangement in a
similar manner to that already described with reference to Figure 3.
All solutions passing to the pump well or to the precipitation troughs are
preferably strained through vertical screens formed of cloth stretched on frames
capable of sliding into grooves formed in the sides of the storage tanks or in
intermediate piers arranged therein. The screens and chases are preferably dupli-
cated so that screens clogged with matters in suspension can be removed and
cleansed without interrupting the process of clarification of the solutions. As the
range of the injector is small, in some cases when treating ore of a very agglutinous
character it may be found advantageous to provide means for preventing the
formation of a cavern or cavity in the material over the injector nozzle. For this
purpose I may provide a supplementary pipe with a small jet or jets directed either
upwards or downwards and working in close proximity to the injector nozzle. By
reason of the operation of the jet the material would be disturbed and so tend to
fall by gravitation to a position within reach of the injector. The said jet may be
conveniently actuated from either of the platforms P or P', when required.
The process can be applied with advantage to the treatment of the whole of the
pulp flowing from the stamp boxes, so that the separation of the slimes with a view
to the obtainment of a leachable product would be unnecessary. The action of the
injector in churning up the ore and solutions renders it immaterial how the fine
and coarse particles of the pulp are distributed in the vat.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is :-
1. Extracting precious metals from crushed ore or slimes or like materials con-
taining them by first intimately mixing the ore with the liquors by a current of
liquid projected into the ore, transferring of the ore to an adjacent vat then
allowing the subsidence of the said ore and finally decanting off the supernatant
solutions and reuse of the solutions before precipitation substantially in the manner
hereinbefore described.
2. For obtaining the intimate admixture of crushed ore or slimes or like
materials with liquors for effecting the extraction of the precious metal or precious
metals therefrom the use of vats for receiving the crushed ore arranged in pairs
with injectors for supplying the liquor under pressure whereby the said ore or the
like is intimately admixed with the liquor and conveyed alternately from the lower
part of one vat to the upper part of the adjacent vat substantially as described.
3. In the extraction of precious metals from crushed ores or slimes or like
materials containing them by treatment with solutions of cyanide of potassium the
concentration of the said solutions when containing but a small amount of a precious
metal or of precious metals by reuse before precipitation substantially as described.
4. In the extraction of precious metals from crushed ores or like materials con-
taining them the use of the apparatus for the purposes explained substantially as

page_text: herein before described and illustrated in Figures 1 and 2 of the accompanying
drawings.
5. The combinations and arrangements of vats and tanks with accessory parts
constituting apparatus for extracting precious metals from ores or materials con-
taining them substantially as herein before described and illustrated in Figure 3
and in Figure 4 of the accompanying drawings.
Dated th: 10th day of March 1806
JOHNSONS & WILLCOX,
47 Lincoln's Inn Fields, London, W.C., Agents.