Improvements in the Separation of Gold from Ores or Materials containing it.
Year: 1890

page_text: Date of Application, 12th Nov., 1890
Complete Specification Left, 31st July, 1891-Accepted, 19th Sept
1801
NAL SPECIFICATION.
Improvements in the Separation of Gold from Ores or Materials
containing it.
I, 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 to be as follows:-
My invention has for its object to provide a process for the separation by
chlorination of gold from ores or materials containing it in which process large
quantities of ore or material can be treated at one operation, no injurious fumes
being evolved and little manual labour being required chlorination and leaching
being effected if desired in but one vessel or vat.
The processes is especially adapted to be carried out in a plant such as is
described in the Specification of my application for Letters Patent No. 3246 of
28th February 1890 and I will describe it in that connection.
According to my invention the finely divided ore or material thoroughly roasted
when necessary is mixed with a proper percentage of a chloride such as dry chloride
of lime and the mixture is placed in the ore vat and there is pumped or passed
through it an agent which will decompose the chloride such as a dilute solution of
sulphuric acid or hydrochloric acid or soda carbonate in such quantity as will be
only sufficient to decompose the chloride gradually or slowly without causing any
noxious fumes to arise from the vat.
filter in connection or communication with the ore vat it is returned to the bottom
As the liquor is passed or forced through the
of the said vat so that only a very small quantity of liquor is required. The liquor
aving been passed through long enough to ensure the dissolution of the gold it is
llowed to percolate or is pumped from the bottom of the leach vat through any
uitable precipitant (preferably a metallic sulphide) and fresh water is forced
hrough the ore until all the soluble gold salts are removed such water passing
way through the precipitant. The ore may now be removed and a fresh charge
troduced.
In place of mixing the chloride with the ore or material I may place it in the vat
ith the ore but separately from the ore.
It is advantageous to use with the acid solution some copper chloride in all cases
Iding such quantity of acid at a time as may be sufficient to cause the slow
gular evolution of chlorine in quantity as required to effect the chlorination.
I may use chlorine generated elsewhere than in the vat itself and pass it together
th the leaching water through the vat in regulated quantity in the manner
scribed.
As an alternative method I may saturate the ore or material with nitric acid
I pump or pass dilute hydrochloric acid through the mass.
Dated this 12th day of November 1890

page_text: COMPLETE SPECIFICATION.
Improvements in the Separation of Gold from Ores or Materials
containing it.
I, WILLIAM DUNSMORE BOHм of 51 Avenue Road, Acton in the County of
Middlesex, England, Metallurgical Chemist and Engineer do hereby declare the
nature of my 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 a process for the separation of gold
from ores or materials containing it in which process large quantities of such ores
or materials can be treated at one operation, no injurious fumes being evolved and
little manual labour being required chlorination and leaching being effected if desired
in but one vessel or vat.
According to my invention I employ bromine or chlorine or a compound yielding
chlorine (or both bromine and chlorine) in the ways hereinafter described.
In using a compound of chlorine finely divided ore or material (thoroughly
roasted when necessary) is mixed with a proper percentage of a chloride such as
dry chloride of lime and the mixture is placed in the ore vat and there is pumped
or forced through it (at a pressure greater than that of the atmosphere and in an
upward direction) an agent which will decompose the chloride such as a dilute
solution of sulphuric acid or of hydrochloric acid or of soda carbonate of such
strength as will be only sufficient to decompose the chloride gradually or slowly
without causing any noxious fumes to arise from the vat." After the liquor
is forced upward through the filter in connection or communication with the ore
vat it is returned to the said vat so that it is circulated and repeatedly rensed and
thus only a very small quantity of solution is required. The solution having been
thus passed upward through the contents of the vat for a time long enough to ensure
the dissolution of the gold contained in the ore or material the said solution is
allowed to percolate or is pumped from the vat through any suitable precipitant
(preferably a metallic sulphide) and afterwards water is forced through the ore until
all the soluble gold salts are removed such water being then passed through the
precipitant to retain any gold present.
The ore may now be removed and a fresh charge introduced and this be treated
as hereinbefore described.
In place of mixing the chloride with the ore or material I may place it in the
vat with the said ore or material but separately therefrom.
It is advantageous to use with the acid solution some copper chloride in all cases
adding such quantity of acid at a time as may be sufficient to cause the slow regular
evolution of chlorine in quantity as required to effect the chlorination. In place of
using a chloride I may saturate the ore or material with nitric acid and pump or
pass dilute hydrochloric acid upward through the mass in the manner hereinbefore
described when the requisite chlorine will be generated or I may use chlorine
generated elsewhere than in the vat itself and pass it through the ore or material
in the vat in regulated quantity in the manner hereinbefore described the ore
or material being previously damped which may be done by passing steam
through it preferably in an upward direction and when the chlorine has been
circulated upward through the ore or material as described with regard to the
solution until all the gold has been converted into soluble chloride of gold it may
be drained off and passed into the precipitator and the ore washed as hereinbefore
described to remove any remaining chloride of gold.
When I employ bromine in place of chlorine a suitable quantity is from th to 2 per
cent. of the ore or material under treatment. The said bromine is mixed with water
to form the leaching solution which is circulated upward through the contents of
the vat as described with regard to the chlorine. In addition to the bromine

page_text: que to that of the bromi
The accompanying drawing represents an apparatus suitable for use in carryin
out the process according to my invention although I do not limit myself to th
5 form of apparatus shewn.
Figure 1 is an elevation shewing the leaching vat in section.
Figures 2 and 3 shew an arrangement of the vat bottom to effect rapid discharg
of its contents.
I will presume that chlorine is to be used as the agent for dissolving the gold i
10 gold bearing ore.
The ore to be treated after being roasted and crushed or divided to the desired
degree of fineness is mixed with the required percentage of chloride or is treated
with chlorine producing material as hereinbefore described and it is then fed into
the leaching vat or vessel A in which the decomposition of the chloride or chlorine
15 producing material is effected.
perforated false bottom a covered with filtering medium a* on which the ore rests
The vessel A is provided with a porous or
and between this false bottom and the bottom proper a³ is a coil of perforated pipe a²
through which the decomposing solution (consisting say for instance of sulphuric
acid and water) is forced by means of the pump C from the tub or vessel B into
20 the vessel A to effect the decomposition of the chloride therein. The vessel A. is
closed at top by a removable lid or cover A² containing a perforated or porous
disc a covered by a hood a³ and provided with a rim a and clamping screws a
whereby the cover may be readily fixed and detached. The decomposing solution
forced by the pump C from the vessel B through the perforated coil of pipe a³
5 passes through the perforated or porous false bottom a into the vessel A until it
is charged to within a short distance of the top or crown of the hood a the
said solution entering the hood through the perforations or pores in the disc at and
cloth a. is an overflow pipe for conducting the solution and afterwards the
wash water from the hood as into a vessel E so that it may be forced through
the vessel G by the pump F. The ore being thus entirely covered with, or
submerged in, the solution the three way cock in the suction pipe 2 of the pump C
is turned so as to close the communication between the pump Cand the vessel B and
open a communication between the pump C and the pipe connecting the hood a
with the suction end of the pump so that by means of the said pump a continuous
circulation of the solution through the pipe and upward through the ore contained
in the vessel A is maintained at a pressure greater than atmospheric pressure until
the decomposition of the chloride and solution of gold by the chlorine are effected.
B2 is a vessel containing sulphuric acid or hydrochloric acid for adding as required
to the solution contained in the vessel A the said vessel B² communicating there-
with by a pipe 3 provided with a cock and connected to the hood a. Any
excess chlorine gas generated or given off from the solution and tending to
escape from it while circulating through the vessel A is conducted by a pipe as in
connection with the hood as into a vessel D containing oxide of lime whereby the
escape of noxious fumes is prevented.
When the ore in the vessel A. has been sufficiently treated with the solution to
nsure the dissolution of the gold contained in the said ore the pump C is stopped
nd the solution is allowed to drain from the vessel A through a pipe e and
ock e² into the tub or vessel E from which it is withdrawn by the pump F through the
action pipe fand forced through the delivery pipe finto the precipitator G or it
ay be allowed to percolate through the precipitator G by leading the pipe
ereinto as shewn in dotted lines at y.
allow vessels arranged one above another and baving reticulated, perforated, or
The precipitator consists of a series of
rous bottoms upon which is placed a suitable solid precipitant (preferably a
etallic sulphide) through which the solution is forced in either an upward or a
wnward direction as desired as indicated by the dotted and full lines of the
When the whole of the solution has drained from the vessel A water is forced

page_text: preferably upwards as in the case of the solution through the ore to remove any
remaining soluble gold salts therefrom the water passing from the vessel through
the pipe into the vessel E whence it is taken by the suction pipe ƒ of the pump F
and forced through the precipitator G to retain any gold that may be present or
it may be allowed to percolate through the vessel G without the use of the
pump F.
If sulphide of copper be used in the process as a precipitant the solution
containing the copper may be conducted from the precipitator G by the pipe g²
into a vessel H containing bars of iron whereby the dissolved copper is precipitated.
To facilitate the discharge of the spent ore from the vessel A the bottom A³
thereof may be hinged to a flange h on the body of the vessel as shewn at 2 in
Figures 2 and 3 and secured in its closed position by bolts and nuts has shewn ;
or by any other suitable fastening. The bottom A³ contains the false bottom and
filtering medium and is attached to a chain or the like k passing over a pulley!
and connected to any suitable hauling device whereby the bottom may be raised
and lowered with facility the connections of the pipes being arranged or the pipes
made flexible to allow of this movement.
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 the treatment of gold bearing ores or materials the employment of chlorine
or of a chlorine yielding compound or of bromine or of both bromine and chlorine
forced in an upward direction at greater than atmospheric pressure through the
ore or material and circulated therethrough continuously substantially as herein-
before described.
2. The treatment of gold bearing ores or materials by placing them and a chloride
such as chloride of lime in a vat or vessel and forcing and circulating upward
through the mixture at greater than atmospheric pressure, an agent which will
decompose the chloride as and for the purpose hereinbefore described.
3. The treatment of gold bearing ores or materials by saturating them with nitric
acid placing them in a vat or vessel and forcing and circulating dilute hydrochloric
acid through the mass at greater than atmospheric pressure and in an upward
direction as hereinbefore described.
4. The treatment of gold bearing ores or materials by charging a vat or vessel
therewith damping the charge and forcing and circulating chlorine therethrough
in an upward direction and greater than atmospheric pressure as herein before
described.
5. In the treatment of gold bearing ores or materials the obtainment of soluble
salts of gold in either of the ways hereinbefore described and claimed and then
passing the liquid from the vat or vessel in which the treatment takes place through
a precipitant, then passing water through the charge in the vat or vessel and
passing this also through a precipitant all substantially as hereinbefore described.
6. The separation of gold from ores or materials containing it by treatment as
described in an apparatus arranged as herein before described and shewn in the
accompanying drawing Figure 1.
Dated this 31st day of July 1891.
J. H. JOHNSON & Co.,
Agents.