Improvements in the Wet Method of Extracting Gold.
Year: 1889

page_text: Date of Application, 2nd Apr., 1889
Complete Specification Left, 22nd June, 1889-Accepted. 29th Mar.. 1890
PROVISIONAL SPECIFICATION.
Improvements in the Wet Method of Extracting Gold.
I, JAMES HOLMS POLLOK B. Sc., of the University of Glasgow, in the county of
Lanark North Britain, assistant to the Professor of Chemistry in the said University,
do hereby declare the nature of this invention to be as follows:-
This Invention relates to the process of extracting gold from crushed ores or
other finely divided auriferous material by means of chlorination under hydraulic
pressure as described and claimed by me in my Complete Specification, No. 17495,
and dated 20th December 1887:
This Invention consists in an improved mode of applying this hydraulic pressure
whereby the application of the said hydraulic pressure is made more easy, continuous,
and effective. This improvement consists in the co tinuous application of hydraulic
pressure to the rotating vessel in which the process of chlorination is being conducted,
by means of a pipe leading from the accumulator or pump to the cylinder, and passing
through the centre of rotation at one end of the cylinder to which it is constantly
attached and kept tight by means of a packing box, which, while it keeps the pipe
perfectly tight, leaves the cylinder free to revolve.
In operating, the ore is first crushed and roasted in the usual manner, then mixed
with about 1% of bleaching powder, and 1% of bisulphate of soda, and charged
into the chlorinating cylinders. These cylinders, Figure 1, are made of steel,
protected from corrosion by a suitable lining such as lead, or lead and stoneware-
stoneware being preferred to wood as it is not so readily worn away by the attrition
of the ore in the cylinder-and supported on four friction wheels, and caused to
revolve by a shaft passing through two of these wheels. A, is the charging door;
B, the air escape and chlorine blow off valve; C, the pipe passing to the accumulator,
supplying water at a pressure of about 100 lbs. per square inch; D, hydraulic pressure
supply valve. At the point E, is an automatic India-rubber valve, which, while it
admits of the free flow of water into the cylinder prevents the ore or solution from
finding its way into the hydraulic pipe. F, is a suitable filter; and G, a tank for
precipitating the gold in. So soon as the ore and reagents are placed in the cylinder
the charging door is closed, and the valve D, opened, when water rushes in at a
pressure of 100 lbs. per square inch. Advantage is gained by allowing the valve B,
to remain open during the admission of the water, and until the cylinder is completely
filled with water when the valve B, is closed. By this means any residuum of air
originally in the cylinder is expelled or allowed to escape, the presence of air in the
cylinder being undesirable and detrimental in consequence of its absorption of part of
the chlorine, rendering it useless for the purpose of dissolving the gold. When the
cylinder is full, and the valve B, closed, the cylinder is revolved without closing the
valve D, whereby the accumulator or other water forcing device exerts its pressure
throughout the whole operation. When the chlorination is completed, the valve D, is
closed, and a pipe leading to tanks containing lime is connected to the valve B, and
the chlorine blown off and absorbed by the lime. The cover is then removed from
the charging aperture, and the ore & solution of gold are poured out into the
filter F. The solution of gold as it filters through is run into the tank G, and
precipitated by ferrous sulphate or other suitable precipitant.
Having now particularly described and ascertained the nature of my said. Inven-
tion, and in what manner the same is to be performed, I would point out that the
special feature of this Invention is :-
The application as hereinbefore described of continuous hydraulic pressure to the
revolving cylinder wherein the wet method of chlorination is conducted, by means of

page_text: a pipe, passing through the centre of rotation of one end of the cylinder, and connected
to the said end by a suitable packing box, so as not to interfere with the revolving of
the said cylinder.
J. HOLMS POLLOK,
Applicant.
COMPLETE SPECIFICATION.
Improvements in the Wet Method of Extracting Gold.
I, JAMES HOLMS POLLOK, B. Sc. of the University of Glasgow, in the County of
Lanark, North Britain, Assistant to the Professor of Chemistry in the said University
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 which relates to the process of extracting gold from crushed ore, or
other finely divided auriferous material by means of chlorination under hydraulic
pressure as claimed by me in my Complete Specification No. 17495, dated 20th
December 1887, has for its object to make the application of hydraulic pressure more
easy, continuous and effectual, and thereby to cheapen, expedite, and render more
effectual the extraction of gold.
The Invention consists in the continuous application of hydraulic pressure to the
rolating vessel in which the process of chlorination is being conducted, by means of a
pipe leading from the accumulator, pump, injector, or other water-forcing device, to
the cylinder, and passing through the centre of rotation of one end of said cylinder,
to which it is constantly attached and kept tight by means of a packing-box, which
keeps the pipe perfectly tight, but leaves the cylinder free to revolve.
In operating, the ore when necessary is first crushed, concentrated, roasted, or
otherwise prepared, and is then placed in a suitable revolving cylinder together with
the-requisite reagents, the cylinder being properly protected from the corrosive action
of the chlorine and of sufficient strength to withstand the pressure applied. So soon
as the ore and reagents are placed in the cylinder the air is removed, after the manner
more particularly described-in-my specification No. 16796, dated 19th November 1888;
and water is forced in. When the cylinder is completely filled with ore, reagents, and
water, it is closed and revolved; the valve on the water and pressure supply pipe
hoing allowed to remain open, whereby the hydraulic pump, accumulator, injector, or
other water-forcing device exerts a continuous pressure throughout the whole
operation. When the chlorination is completed the valve on the hydraulic press wire
supply pipe is closed, and the excess of chlorine blown off by a suitable valve for that
purpose, or is sucked out or otherwise removed. The cover is then removed from the
machine, and the ore and solution are discharged on a suitable filter, when the
solution of gold is drawn off, and the gold precipitated and recovered by any suitable
means.
In the drawing accompanying the provisional specification, I have illustrated in
side elevation, apparatus well adapted for carrying out my invention. The apparatus
consists of a steel cylinder lined with lead, stone-ware, or other non-corrodible
substance, and capable of receiving rotary movement by means of gearing not
illustrated. There is a door at A for charging the cylinder. B is an air escape or
chlorine blow off valve. (is the water pressure supply pipe entering the cylinder at
the centre of rotation, so that the hydraulic pressure may be continuously applied.
D is a valve for regulating the hydraulic pressure. At E is an automatic valve, which,
while it admits the free flow of water into the cylinder, prevents the ore or solution
from finding its way into the hydraulic pipe. F is a filter, and G a tank for precipi-
tating the gold.
It is to he, understood that in practising this invention, altough the machinery
described and illustrated is suitable for the purpose, any other suitable machinery may

page_text: be employed. It is also to be understood that in place of chlorine, or chlorine
generating agents, bromine, or iodine, or bromine or iodine generating agents may be
employed.
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:-
The application as herein before described of continuous hydraulic pressure to the
revolving cylinder wherein the wet method of extracting gold by chlorine, bromine, or
iodine; is conducted, by means of a pipe passing through the centre of rotation of one
end of the cylinder, and connected to the said end by a suitable packing-box, so as not
to interfere with the revolving of the said cylinder.
Dated this 20th day of June 1889.
J. HOLMS POLLOK,
Applicant.