Improvements in the Wet Method of Extracting Gold from Crushed Ores or other Finely Divided Auriferous Material.
Year: 1888

page_text: Date of Application, 19th Nov., 1888
Complete Specification Left, 8th June, 1889-Accepted, 16th Nov., 1889
PROVISIONAL SPECIFICATION.
Improvements in the Wet Method of Extracting Gold from Crushed
Ores or other Finely Divided Auriferous Material.
I, JAMES HOLMS POLLOк 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, which relates to improvements in the wet method of extracting
gold from crushed ores or other finely divided auriferous material, has for its object to
get rid of practically the whole of the air contained in the vessels wherein the chlorination
process for extracting gold is practised whereby the entire volume of the vessel is
utilized by being completely filled or practically so with the water, bleaching powder
and other substances constituting the charge. In effecting the escape of the whole of
the air contained within the vessel the hydraulic pressure apparatus whether it be a
hydraulic pump, accumulator or other water forcing apparatus is caused to completely
fill the vessel with water either during the time that the said vessel is stationary or
the pressure may be kept on during the rotation of the vessel.
The foregoing improvement is not only applicable to the process wherein the
extraction of gold is effected by the action of chlorine obtained from bleaching powder
but it is also applicable when iodine or bromine or other substances containing
chlorine, iodine or bromine are used.
A further feature of improvement in connection with the obtainment of gold from
ores or other auriferous material consists in chlorinating at or about 60° C.. but which
temperature varies according to the character of the ore or auriferous material under
treatment. This hot chlorinating may be effected either by using water heated
previously to its being admitted to the chlorinating vessel by placing the ore or
auriferous material in a hot state in that vessel.
It is to be understood that the foregoing improvements are specially applicable in
connection with the improvements described in my Specification No. 17495 of 1887.
Dated this 17th of Nawamba. 1900
ST. JOHN V. DAY,
115, St. Vincent Street, Glasgow, Petitioner's Agent.
ST. JOHN V. DAY,
115, St. Vincent Street, Glasgow, Petitioner's Agent.
COMPLETE SPECIFICATION.
Improvements in the Wet Method of Extracting Gold from Crushed
Ores or other Finely Divided Auriferous Material.
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:-
My Invention, which relates to the extraction of gold from crushed quartz or other
auriferous material, and more particularly from refractory ores, float gold ores, or
tailings, has for its object the cheapening, expediting, and rendering more effectual
the process of extracting gold, more particularly the process of extracting gold from
crushed ores by means of chlorination under hydraulic pressure, as described by me
in my specification No. 1749587.
According to my Invention I remove the air from the vessel in which the ore is
placed prior to the extraction of the gold therefrom, and force in water heated to
about 60° C.
The improvement will be better understood and its value more readily appreciated
from the following complete description of one of the best ways of working the
process of chlorination under pressure.

page_text: The ore whether of the free milling, float, refractory, or other variety is first
crushed to a suitable fineness, and if the ore is poor and its character permits con-
centration, then if necessary the ore is roasted to oxidize the metals present, salt or
other reagent being added in the roasting when this is found to be desirable from the
complex character of the ore or otherwise. After roasting, the ore is allowed to cool
or partially cool and together with the requisite reagents is charged into a suitable
revolving cylinder made of sufficient strength and properly protected from the
corrosive action of the chlorine evolved in the operation. The reagents used to
generate the chlorine are charged into the cylinder the one before and the other after
the ore to avoid the liberation of chlorine before the closing of the cylinder and the
revolving of the same.
After the ore and reagents are placed in the cylinder the air is removed from the
said cylinder by a suitable stop cock placed on the cylinder for that purpose and this
may be effected by any air removing device such as an air pump, or the admission of
the water may itself be made the means of removing or expelling the air. When the
air is removed or during the removal of the same, water is forced into the machine by
any known water forcing device, the water being heated to about 60° C. simultaneously
to its introduction, either prior to or during the revolution of the cylinder. For tho
purpose of forcing in the water and simultaneously heating the same a steam injector
may conveniently be used, as by properly regulating it the water can be thrown in at
the temperature and pressure required. So soon as the cylinder is completely filled
with ore reagents and water, the steam acts as a very convenient and economicul
water forcing device, for it presses on the condensed water in the supply pipe and
forces it into the cylinder, thus exerting a hydraulic pressure in the cylinder equal to
the steam pressure in the boiler. So soon as the air is removed and the heated water
forced in, or after the removal of the air and during as well as after the forcing in of
the water, the cylinder is revolved; and in the absence of air and at or about the
temperature of 60° C. and under the hydraulic pressure the chlorinating liquid
rapidly attacks and dissolves the contained gold converting it into chloride.
When this is done the excess of chlorine is blown off or removed by an asperator or
otherwise, and the ore and solution are discharged on a suitable filter and the solution
drawn through and delivered into suitable tanks by means of a Korting ejector as is
well understood and has been practised in America and elsewhere for many years; or
the filtration may be assisted by a vacuum pump after the manner practised in many
alkali works in this Country and first patented by Spencer in the United States of
America 4th June 1867. In cases where copper and silver are present with the gold
the liquid may, by means of a steam ejector, be made to circulate through the ore in a
hot state for some time before removal from the filter, as this greatly assists the
solution of the silver. The ore is finally washed with water and the solution together
with the washings aro precipitated with ferrous sulphate or other suitable precipitant,
and the gold collected, dried and fused into bars.
It is to be understood that this improved method is equally applicable when bromine
or iodine are used in place of chlorine.
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. The removal of air from the cylinder or vessel containing the ore and reagents;
either prior to the admission of water, or during the admission of the same, but prior
to the revolving and chlorinating of the ore.
2. The heating of the water to about 60° C. simultaneously to the injection of the
same, or after the introduction of the same, or before the introduction of the same.