Improvements in and Apparatus for the Separation of Gold and Silver from Ores or Materials containing them.
Year: 1890

page_text: Date of Application, 28th Feb., 1890
Complete Specification Left, 15th Dec., 1890-Accepted, 7th Feb., 1891
PROVISIONAI, SPECIFICATION.
Improvements in and Apparatus for the Separation of Gold and
Silver from Ores or Materials containing them.
I, WILLIAM DUNSMORE BOHм, of 51, The Avenue, Acton, in the County of
Middlesex, Metallurgical Chemist and Engineer, do hereby declare the nature of
this invention to be as follows:-
My invention has for its object to provide means whereby gold or silver or both
can be obtained very conveniently and efficiently from ores or materials containing
them with but little hand labour and great economy in time and materials
employed.
According to my invention 1 place the powdered or divided ore or material to be
treated for the obtainment of the gold or silver or both in a vessel and through it I
pass the leaching solution which I preferably previously heat. I preferably
force the leaching solution up through the ore and through a filter I then pass the
solution and the precious metal which it now contains into a vessel in which [
agitate it with a precipitating agent. From this last named vessel the solution is
passed into a vessel having a filtering arrangement such as a porous diaphragm or
top so that the solid matter precipitates out the liquid passing off to be heated
At intervals the contents
again and passed back to the leaching vessel for re-use.
f the last named filtering vessel are passed into a filter press or equivalent apparatus
wherein they are deprived of the greater part of their moisture. The ore which
has been leached is then drained of all solution and washed free from the last traces
thereof with hot water and then is washed out of the vessel with acidulated water
and passed over a plate of zinc or alloy of zinc with other suitable metal so that
hydrogen is evolved which reduces any precious metal still remaining in the ore to
the metallic state so that it is taken up when the ore is afterwards passed over an
amalgamated copper plate.
I preferably arrange the apparatus with two leaching vessels so that they can be
worked alternately and I will describe an arrangement of apparatus according to
my invention on this plan. The two leaching vessels are placed in convenient
proximity to each other. Each of them is provided with a porous or perforated
false bottom upon which the ore to be treated rests and under this is the coil or the
like by which the leaching solution is admitted in such a manner that it is equally
distributed over the bottom of the vessel the said coil or the like being preferably
perforated at its underside in places which are pressed in so as to be clear of the
bottom of the vessel. The coil or pipe leads from a tank or vessel containing the
solution which is heated in any suitable way for instance by a jacket or a coil
through which hot water is passed but I preferably employ a heating chamber
placed in, or on, or in proximity to, the flue of the boiler by which water may be
heated to be passed into a jacket surrounding, or coil in, the vessel into which the
solution is passed from the precipitating vessel. I employ a force pump which
draws the solution from a tank into which it is run after it is heated and in
which solvents such as hydrochloric acid and bromine or either of them
may be added to it the said pump forcing the solution into the leaching vessel.
In this tank chloride of sodium may be placed to preserve the strength
of the solution. The upper part of each leaching vessel is provided
with a filtering medium preferably stretched over a perforated false head.
The hole therein through which the ore is charged is preferably covered also with
filtering material secured by means of a ring screwed down onto a bushing in the
said hole which bushing is provided with a screwed ring and flange by which latter
the edge of the main part of the filtering material is held between itself and the
perforated false head. The solution after passing through the ore is discharged

page_text: IS
into a mixing apparatus situated between the leaching vessels and provided
with reciprocating or rotating stirrers or other agitating device and having
in connection with it a vessel containing a precipitating agent which
fed into the solution in the said agitating vessel by means of a tap or
valve controlled so that it passes only a quantity of the precipitating agent, in
proportion to the quantity of solution passing. This tap or valve may be operated
by the weight or pressure of the solution passing so that the solution by entering
for instance a vessel may by its weight or by raising a float, operate a lever with
which it is connected, which lever opens the tap which supplies the precipitating
agent, and when the solution decreases in flow or ceases flowing the said tap is
correspondingly partly or fully closed. The solution with the metal in suspension
is then run into a receiver from which it is drawn by a pump, and delivered into
the vessel in which it is passed upwards through a filter, and the precipitate
retained to be at intervals discharged into a filter press or the like. The liquid
which passes through the filter is discharged into the vessel which is heated by the
hot water or other heating agent and is then run into the vessel in which the
requisite chemicals are added to fit it for re-use in the leaching vessel when drawn
from the said vessel by the pump which forces it into the leaching vessel. The ore
may then be washed as herein before mentioned as during the process the solution
becomes weaker owing to the addition of water it is preferably before re-use in the
leaching vessels passed through an evaporator or concentrator. After the charge
of ore in either of the leaching vessels has been leached as described, its communi-
cation with the force pump is closed and acidulated water is passed into the
leaching vessel, and the ore washed out passing down a guide or shoot leading from
the outlet of the vessel to the zinc and amalgamated plates herein before mentioned.
To remove matter remaining in the leaching vessel I may use a rake connected
with a rod passing through the vessel so that it can draw the rake back (the teeth
yielding to allow of this) and then by means of a rope connected with a purchase
pulley, the rake and with it the ore can be drawn towards the discharge door of the
leaching vessel.
Instead of using a separate heater for the leaching solution it may be heated by
a hot water coil or the like in the leaching vessel below the perforated false bottom,
or the heat in the evaporator or concentrator alone may be depended upon for
heating the solution.
In place of passing the leaching solution through the leaching vessels by a pump
it may be passed thereinto under the pressure due to its head, and it may be
passed downwards instead of upwards when the filter will be at bottom instead of
at top, and the top be fitted with a close cover.
When using two leaching vessels the pipes are provided with cocks so that the
solution can be forced into either leaching vessel, whilst the washing out of the
other leaching vessel is being performed.
The filter press may be of any suitable kind but I prefer to use one consisting of
a casing with inlets for the matter to be pressed, and for air or gas under pressure
and with a hollow bottom with an outlet for liquid and with a perforated false bottom
covered with filter cloth. This hollow bottom, and the false bottom are preferably
so connected to the casing that they can be swung down, or, to one side when desired
for removing the solidified matter. In this casing and connected to an outlet for
liquid is a float made preferably of wood, it is hollow and its interior is connected
by a moveable connection or flexible tube with the outlet for liquid. Its underside
is perforated and is covered with filter cloth. When the matter to be pressed is
introduced the inlet is closed and air under pressure is admitted, the float always
resting on the matter in the filter, and the desired amount of moisture is forced off
through the perforated bottoms of the casing and of the float.
Dated this 28th day of February 1890.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, W.C., Agents.

page_text: COMPLETE SPECIFICATION.
Improvements in and Apparatus for the Separation of Gold and
Silver from Ores or Materials containing them.
J, WILLIAM DUNSMORE BOHM, of 51, The Avenue, Acton, in the County of
Middlesex, Metallurgical Chemist and Engineer, 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 has for its object to provide means whereby gold or silver or both
can be obtained very conveniently and efficiently from ores or materials containing
them with but little hand labour and great economy in time and materials
employed.
According to my invention I place the powdered or divided ore or material to be
treated for the obtainment of the gold or silver or both in a vessel or vat or vessels
or vats and through it I pass the leaching solution which I preferably previously
heat. I force by means of a force pump the leaching solution up through the ore
and through a filter at top I then pass the solution and the precious metal which
it now contains into a vessel in which I agitate it with a precipitating agent. From
this last named vessel the solution is forced up by a force pump through a vessel
having a filtering arrangement such as a porous diaphragm at top so that the solid
matter is retained thereby, the liquid passing off to be heated again and to be
restrengthened by the addition of the necessary further quantity of leaching
chemicals and passed back to the leaching vat or vats for reuse.
The pressure
under which the liquids are forced up through the leaching vat and precipitant
vessel should be at least 18 lbs. per square inch. At intervals the solid matter
retained by the last named filtering vessel is passed into a filter press or equivalent
The ore
apparatus whereby it is deprived of the greater part of its moisture.
which has been leached is then drained of all solution and washed free from the last
traces thereof with water (preferably hot) and then can be washed out of the vat
or vats with acidulated water and passed over zinc or alloy of zinc with other
suitable metal so that hydrogen is evolved which reduces any precious metal still
remaining in the ore to the metallic state or such state that it is taken up
when the ore is afterwards passed over mercury for instance over amalgamated
copper.
I preferably arrange the apparatus with two leaching vats so that they can be
worked alternately and I will describe an arrangement of apparatus according to
my invention on this plan with reference to the accompanying drawings, Figure 1
of which is an elevation partly in section Figure 2 a plan and Figure 3 a transverse
section across the leaching vats the other figures showing details as hereinafter
described. The two leaching vats A A² are placed in convenient proximity to each
other. Each of them is provided with a porous or perforated false bottom a covered
preferably with coarse canvas upon which the ground or reduced ore to be leached
rests and under this is the coil or the like by which the leaching solution is admitted
in such a manner that it is equally distributed over the bottom of the vat. Figure 4
is a plan of the bottom of one of the vats showing the coil in place and Figure 5
is a vertical section of part of the same. The said coil or the like is preferably
perforated at its under side in places which are pressed in as shown at 6,
(Figure 5.) so as to be clear of the bottom of the vat. The coil or pipe /
(provided with cocks 123) leads from a strainer e in a tank or vessel C con-
taining the solution which is heated in any suitable way for instance by a jacket
or a coil through which hot water is passed but I preferably employ a heating
chamber shown at Z but in practice preferably placed on or in proximity to the
flue of the boiler by which water may be heated to be passed into a jacket
surrounding, or coil in, the vessel D into which the solution may be passed from
the vessel J before the said solution enters the tank C. I employ a force pump B
which draws the solution from the tank C into which it is run after it is heated

page_text: and in which solvents such as hydrochloric acid or sulphuric acid and bromine or
any of them may be added to it (from the vessels E and F for instance) the said
pump B forcing the solution into one or the other of the leaching vats according
to which of the cocks 6263 is open. In the tank C chloride of sodium may be
placed to preserve the strength of the solution. The upper part of each leaching vat
is provided with a filtering medium a² preferably stretched over a perforated false
head a³ as shown by the enlarged view of part thereof in Figure 6. The hole a*
therein through which the ore is charged is preferably covered also with filtering
material a secured by means of a ring a screwed down by the screws a³ on to a
bushing a' in the said hole which bushing is provided with a screwed ring a³ and
flange by which latter the edge of the main part of the filtering material a² is held
between itself and the perforated false head a³. The cock and also one or the other
of the cocks 62 or 63 according to which vat is to have its contents leached being open
(the cock on the pipe 65 being closed) the solution passes through the ore in that
leaching vat and then passes by the pipe ao from that vat into a mixing apparatus G
situated between the leaching vats and provided with reciprocating or rotating
stirrers g or other agitating device and having in proximity to it a vessel H
containing a precipitating agent such for instance as polysulphide of calcium which
is fed into the solution in the said agitating vessel G by means of a tap or valve g
preferably controlled so that it passes only a quantity of the precipitating agent in
proportion to the quantity of solution passing this regulation of the quantity
being essential when such a prec pitant as polysulphide of calcium is used because
an excess of the precipitant would negative the result of the previous treatment
by rendering (when the solution is returned to the leaching vat) the metals
insoluble. This tap or valve may be operated by the weight or pressure of the
solution passing so that the solution by entering for instance a vessel may by
its weight or by raising a float operate a lever with which it is connected which
Iver opens the tap which supplies the precipitating agent and when the solution
decreases in flow or ceases flowing the said tap is correspondingly partly or wholly
closed. Figure 7 shows an arrangement wherein a vessel h is used into which the
liquid from the leaching vat enters by the pipe al and normally passes off at the
same rate by the cock 2 but if it enters by the pipe a¹0 more quickly it accumulates
and its weight increases the passage way through the tap y² by acting thereon
through the lever and rack shown the latter operating the tap 2 through the
quadrant upon its plug. The position which the vessel / assumes in relation to the
tap is regulated by the adjustable weight g³.
Figure 8 shows an arrangement wherein a moveable float or piston ³ is used the
vessel / not being itself moveable the parts which correspond with those shewn in
Figure 7 being marked with the same letters of reference. The solution with the
metal in suspension is then run by the cock g' into a receiver I from which it is
drawn through the pipe i and cock 2 by a pump B2 and delivered by the pipe ³
into the vessel J in which it is passed upwards through a filter and the solid
matter is retained to be at intervals discharged by the pipe j and cock into a
filter press Kor the like the liquid from which can run into the tank Č. The
liquid which passes through the filter is discharged by the pipe ³ and cock j* into
the vessel D which is heated by the hot water or other heating agent in any
suitable way for instance by the coil as shewn led from the hot water tank Z as
herein before mentioned. The solution is then run by the pipe d and cock d² into
the vessel C in which the requisite chemicals are added to fit it for reuse in the
leaching vats and whereupon it is drawn by the pump B which forces it into the
leaching vats as already explained. The ore may then be washed with hot water
drawn from the tank Z by the pump B through the pipe 65 and cock 6° (cocks b*
and either 63 or 67 being closed) it passing through one or other of the vats into
the mixer and is pumped up through the filtering vessel J and from thence passes
by the pipe Jx and cock to the evaporator L where it is concentrated before
being admitted by the pipe 12 to the vessel C. The vessel D can communicate
directly with the evaporator L through a pipe 1.

page_text: The vessel J may contain layers of granulated or "cement"
copper supported
upon perforated trays for precipitating any precious metal or this may be effected
by electrolysis by providing the vessel with electrodes in both of which cases it
will only be necessary to force the liquor containing the precious metals in solution
through the vessel J to effect precipitation no polysulphide of calcium or other
precipitating agent being used in addition so that I may if desirable connect the
suction pipe i of the pump B2 directly to the pipe a of either of the vats A
or A2 and force the solution directly into the vessel J without first passing it
through the agitator G and the receptacle I.
After the charge of ore in either of the leaching vats has been leached and
washed as described the communication with the force pump is closed and
acidulated water is (by a hose or other convenient means) passed into the leaching
vat and the ore washed out the said ore passing down a guide or shoot. M leading
from the outlet of the vat to the zinc and amalgamated plates marked m and m
respectively. Or I may remove matter remaining in the leaching vat without
washing it over the plates mand m² in which case I use a rake n as shewn in
Figure 9 connected with a rod 2 passing through the vessel so that it can draw the
rake back (the teeth yielding to allow of this) and then by means of a rope
connected with a purchase pulley n³ the rake and with it the ore can be drawn
towards the discharge door of the leaching vessel. A purchase pulley and rope
may also be provided as shewn for drawing back the rake.
is a pipe and 2 are cocks by which the leaching solution which it may be
required to pass from the vats to the tank C can be drawn off.
Instead of using a separate heater for the leaching solution it may be heated by
a hot water coil or the like below the perforated false bottom in the leaching vat
as shewn with regard to the vat A2 in Figure 3 or the heat in the evaporator or
concentrator L alone may be depended upon for heating the solution.
In place of passing the leaching solution through the leaching vessels by a pump.
it may be passed thereinto under the pressure due to its head.
When using two leaching vats the pipes are provided with cocks as shewn so
that the solution can be forced into either vat whilst the washing out of the other
vat is being performed or if desired the contents of both vats may be leached at
the same time. The leaching vats may if desired be provided with stirrers or
agitators to stir or agitate the charge during treatment.
The filter press may be of any suitable kind but I prefer to use one such as is
shewn at Figure 10 consisting of a casing P with an inlet p for the matter to be
pressed led by a flexible tube down to just above the float R (or as shewn in dotted
lines at p³) and inlets ppl for air or gas under pressure and with a hollo y bottom pt
with an outlet for liquid and with a perforated false bottom g covered with filter
cloth. This hollow bottom and the false bottom are preferably so connected to the
casing (as shewn) that they can be swung down or to one side when desired for
removing the solidified matter. In this casing and connected to an outlet r for
liquid is a float R made preferably of wood it is hollow and its interior is connected
by a moveable connection or flexible tube with an outlet for liquid. The under
side of the float R is perforated and is covered with filter cloth. When the
matter to he pressed is introduced the inlet p or p³ is closed and air under pressure
is admitted at p the float R always resting on the matter in the filter and the
desired amount of moisture is forced off through the perforated bottom 4 of the
casing and the perforated bottom of the float. The inlet for air is opened
when it is desired to agitate the matter being pressed.
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. The arrangement and combination of parts constituting an apparatus for
separating gold and silver from ores or materials containing them substantially as

page_text: hereinbefore described and shewn in Figures 1, 2 and 3 of the accompanying
drawings.
2. In apparatus for the purpose described a leaching vat provided with a filter
at its upper part and with means for pumping liquid at a pressure such as herein-
before mentioned up through it substantially as hereinbefore described.
3. The combination in apparatus for the purpose described of a leaching vessel
or vat and means as described for pumping the leaching agents therethrough as
hereinbefore described and in an upward direction and means as described for
separating the solid matter and for treating and returning the leaching liquid to the
leaching vessel or vat substantially as herein before described.
4. The filter press constructed as hereinbefore described and shewn in Figure 10
of the accompanying drawings.
5. The process of treating ores or materials containing gold or silver or both for
the separation of gold and silver therefrom substantially as and by means of the
apparatus herein before described.
Dated thin 97th 1
1
1000
J. H. JOHNSON & Co.,
Agents.