Improvements in the Wet Process for the Extraction of Gold or Silver, or both, from Pulverised Ores or other Finely Divided Material, and in Apparatus therefor.
Year: 1892

page_text: Date of Application, 24th Aug., 1892-Accepted, 24th Sept., 1892
COMPLETE SPECIFICATION.
Improvements in the Wet Process for the Extraction of Gold or
Silver, or both, from Pulverised Ores or other Finely Divided
Material, and in Apparatus therefor.
I, JOSEPH WILLIAM SUTTON, of Eagle Street, Brisbane, in the Colony of
Queensland, 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:-
This invention relates to improvements in the wet process or method of extracting
gold or silver or both by chlorine from pulverised ores or other finely divided
material, and to apparatus therefor.
:
The object of these improvements is, Firstly to effect a thorough and constant
circulation of the pulverised ore in the chlorinator, thus lessening the time occupied
in chlorinating Secondly to separate and leach out the gold or silver solutions
from the chlorinated ore more rapidly, effectually, and economically than has
hitherto been done; Thirdly to shorten the time taken in filtering the gold or
silver precipitates, and Fourthly: to evaporate all the surplus spent liquid, so as to
retain any gold or silver still left.
According to my invention the pulverised ore or other finely divided material is
placed in a chlorinator consisting of a closed chamber, preferably cylindrical, within
which is a screw conveyor provided with an open-ended cylindrical casing. On
the screw conveyor being revolved at a moderate speed the ore is carried up to the
top of the chamber and falls into the space between the casing of conveyor and the
side of the chlorinating chamber, so that the ore is in constant motion while
the screw is being revolved. The necessary chlorine may be obtained by adding
bleaching powder, sulphuric acid and water to the ore in the chlorinator as is well
known but I prefer to provide a chlorine generator of known construction with
connection to the chlorinator.
When the chlorination of the gold or gold and silver is complete, the contents
of the chlorinator are discharged into a receiver, from which it is drawn in required
quantities into a hydro-extractor, the basket of which is revolved at a high rate of
speed. By this means the solid material is retained in the basket of the hydro-
extractor, and is there thoroughly leached or washed by a spray of water until the
gold solution is washed out into the onter cylinder of the hydro-extractor.
If it is not desired to treat the ore for silver, the spent material is then
discharged into a truck for conveyance to waste heap, and a fresh charge run in
from the receiver.
The solution containing the gold is conveyed to a tank, froin which it is raised to
the precipitating vat-or it may be conveyed directly into the precipitated vat
where the gold is precipitated preferably by sulphate of iron. The precipitate is
then run into a small hydro-extractor where it is separated from the liquid. This
liquid is discharged into a tank, from which it may be pumped back to the
chlorinator for a fresh charge. The surplus liquid is passed into an evaporating
tank, thus ensuring the retention of any gold still left.
When there is sufficient silver in the ore to pay treatment, after the solution
containing the gold has been discharged from the hydro-extractor, the remaining
solid material is leached with a solution of hyposulphite of sodium, or it is first
transferred to a vat and digested with hyposulphite of sodium, and then placed in
a hydro-extractor and leached with a spray of water, the operation being. continued
in separate apparatus, and similarly to that herein described for the recovery of
gold, with the exception that in the precipitating vat a precipitate for silver is used
instead of one for gold.
In order that the apparatus by which the process is carried into effect may be the

page_text: better understood, I will now proceed to describe the same by reference to the
accompanying drawing, which is a sectional elevation of an entire plant. A is a
chlorine generator which may be of known construction. B is a chlorinator
consisting of a cylinder of iron B, and lined with lead. B is screw conveyor
covered with lead or porcelain and provided with an open-ended cylindrical
casing B³, suitably supported on brackets B. 136 is packing gland for spindle of
screw conveyor. B is thrust journal for supporting screw conveyor. B' is gearing
connected with motive power for driving screw. 138 is discharge door; B charging
door; B10 relief valve. B" conduit pipe from chlorine generator, entering at top
and running to bottom of chlorinator. B is steam pipe for clearing chlorine
pipe B in case of getting stopped with ore. C is receiver for chlorinated ore, and
which may be covered and provided with a ventilator for carrying off the fumes of
chlorine. Cis slide door for drawing off the chlorinated ore. D is a hydro-
extractor of known construction. D' is basket constructed of iron, with lead lining,
and perforated and provided on its inner side with asbestos cloth or other filtering
material. D is outer casing, also lead lined. D³ is exit pipe for solution containing
the gold. D is truck for conveyance of waste material. D is sliding cover for
discharge opening D". D' is perforated pipe for leaching ore in basket.
E is tank for the reception of the chloride of gold solution. E is cock with
receiving funnel. E is steam pipe; E3 gauge glass; E plug-hole for cleaning out
tank when necessary. F is precipitating vat; F pipe from tank E; F2 coil of
pipe F perforated underneath; pipe for conveying precipitate and liquid to
a small hydro-extractor G, similar to hydro-extractor D. His tank for spent
liquid tank for evaporating surplus liquid by means of steam coil I!.
The operation of the process for the extraction of gold or gold and silver from
pulverised ores or other finely divided material by means of my apparatus is as
follows:-
The pulverised ore or other finely divided material having been roasted if
necessary, is either mixed with water to a mortar-like consistency and run into
the chlorinator through charging door B, or the water may be put into the
chlorinator, and motion given to the screw while the dry ore is admitted through
the charging door, thus making the chlorinator perform its own mixing. When
the chlorinator is nearly full the charging door B is screwed down, chlorine
turned on from generator A, and relief valve B opened. The screw conveyor B
is kept revolving, thus causing the ore to be in constant motion until the whole of
the gold and silver is converted into chlorides, which time will depend on the
nature and quality of the ore, but for ores containing gold and silver in a fine
state of division, a charge of about five tons can be chlorinated in about two hours.
When the ore is sufficiently chlorinated it is discharged through door B into
receiver C, from which it is drawn off in suitable charges into the hydro-
extractor D. The basket D' being revolved at a high rate of speed, the solution
containing the gold is expelled from the ore through the filtering material and
perforated sides of basket.
The ore in the basket is then leached or washed with clean water from perforated
pipe D', and I find that about half-a-gallon of water is sufficient to leach or wash
out all the solution containing the gold from a charge of about one-fifth of a ton
in from five to seven minutes.
If it is not desired to treat the ore for the recovery of the silver as herein-
after described, sliding cover D is raised and the spent ore thrown out through
discharge door D into truck D₁ for conveyance to waste heap and a fresh charge
of chlorinated ore drawn into basket.
The solution containing the chloride of gold having been retained by the
outer casing D is discharged by pipe D³ into receiver E. When it has been
ascertained by means of gauge glass E that receiver is full, cock E is
closed and steam admitted at E and the whole of the solution forced up
through pipe F and distributed by perforated coil F over the surface of
precipitant in tank F.

page_text: The gold having been precipitated preferably by sulphate of iron, is dis-
charged together with the liquid by pipe F³ into filtering hydro-extractor G,
where the precipitate is retained in the basket from which it is scooped out
from time to time and the gold melted in the usual way. The liquid retained
within the outer casing of hydro-extractor G is run into tank H and may be
pumped back to chlorinator to mix with further charges.
When charcoal is the precipitant and filtering medium used, the hydro-
extractor G is dispensed with, the liquid passing through the charcoal being
conveyed direct to tank H.
The surplus water (caused by the washing or leaching from pipe D' in hydro-
extractor D) is passed into tank I, where it is evaporated by means of steam
coil 1, care being taken not to raise the temperature of the water over 212°
Fahrenheit. This ensures against any loss of gold which might occur through
imperfect precipitating or filtering.
When it is desired to extract the silver from the ore, after the solution con-
taining the gold has been discharged from the hydro-extractor the remaining
ore in the basket is washed or leached with a solution of sodium hyposulphite
through pipe similar to D7 to dissolve the chloride of silver, or the ore may be
first transferred to a yat (not shown) and there digested with sodium hypo-
sulphite solution. After being properly digested it is placed in hydro-extractor
and there washed or leached with a spray of water from pipe D'. The solution
containing the silver is run into a separate receiver and the operation continued.
in separate apparatus similarly to that herein described for the recovery of gold,
a precipitate for the silver being used in the precipitating vat instead of one
for gold.
When the ore contains a large proportion of silver and little or no gold, it
is not chlorinated in the manner previously described, but is roasted with
chloride of sodium to obtain chloride of silver. The material is then treated
in a hydro-extractor such as D, and the operation continued as herein before
described.
It will be understood that all parts of the apparatus exposed to the action of
chlorine are either lined with lead porcelain or other known chlorine-resisting
material.
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 :-
:-
First. In the wet process for the extraction of gold or gold and silver from
pulverised ores or other finely divided material, subjecting the ore in the chlorinating
chamber to constant circulation by means of a screw conveyor substantially as
herein before described and explained.
Second. In the wet process for the extraction of gold or silver from pulverised
ores or other finely divided material, separating and washing or leaching out the
solution containing the gold or silver from the ore in a hydro-extractor substantially
as hereinbefore described and explained.
Third. In the wet process for the extraction of gold or silver from pulverised
ores or other finely divided material, filtering the gold or silver precipitate from the
liquid in a hydro-extractor substantially as hereinbefore described and explained.
Fourth. In the wet process for the extraction of gold or silver from pulverised
ores or other finely divided material, evaporating the surplus spent liquid so as to
prevent any loss of gold or silver which might be caused by imperfect precipitation
or filtration substantially as hereinbefore described and explained.
Fifth. My improved process for the extraction of gold or silver or both from
pulverised ores or other finely divided material consisting essentially in subjecting
the pulverised ore or other material in the chlorinating chamber to constant
circulation by means of a screw conveyor, separating and leaching out the solutions
containing the gold or silver by means of a hydro-extractor, filtering the gold or

page_text: silver precipitates in a hydro-extractor and evaporating all the surplus spent liquid
substantially as hereinbefore described and explained.
Sixth. In apparatus for the extraction of gold or silver or both by chlorine from
pulverised ores or other finely divided material, the combination with a chlorinating
chamber or vessel of a screw conveyor such as B2 provided with a casing such as B³
having suitable supports such as B substantially as hereinbefore described and
explained, and as illustrated in the drawing.
Dated this 24th day of August 1892.
PHILLIPS & LEIGH,
22, Southampton Buildings, Chancery Lane, London, W.C.,.
Agents for the Applicant.