Improvements in Obtaining Gold and Silver from Ores and other Compounds.
Year: 1887

page_text: The decision of the Comptroller-General, of the 20th day of August 1895, allowed,
under Section 18 of the Patents, &c. Act, 1883, an Amendment of this
Specification.
Date of Application, 19th Oct., 1887
Complete Specification Left, 26th July, 1888-Accepted, 10th Aug., 1888
PROVISIONAL SPECIFICATION.
Improvements in Obtaining Gold and Silver from Ores and other
Compounds.
We, JOHN STEWART MAC ARTHUR, Analytical Chemist, of 15 Princes Street,
Pollokshields, in the County of Renfrew, North Britain, ROBERT WARDROP
FORREST, M.D., and WILLIAM FORREST, M.B., both of 319 Crown Street,
Glasgow, in the County of Lanark, North Britain, do hereby declare the nature
of this invention to be as follows:-
This invention has principally for its object the obtaining of gold from its ores
or other compounds, but it is also applicable for obtaining silver from its ores or
compounds, and it comprises an improved process which whilst applicable to ores
or compounds generally is effectual with ores and compounds from which gold or
silver have hitherto not been easily obtainable.
In carrying out the invention the ore or other compound in a powdered state is
treated with a solution containing cyanogen or a cyanide (such as the cyanides of
potassium, sodium or ammonium) or other substance or compound containing or
yielding cyanogen, till all or nearly all of the gold and the silver are dissolved;
the operation being conducted in a wooden vessel or a vessel made of or lined with
a material not acted on to any considerable extent by the solution or substances
contained therein. The solution is then drawn off and the metal or metals are
recovered by any suitable process, and the cyanogen, cyanide or substance con-
taining or yielding cyanogen may be regenerated. The cyanogen or substance
containing or yielding cyanogen may he used as such, or such materials may be.
taken as will by mutual action form cyanogen or substances containing or yielding
Bame.
Under certain circumstances it may be found desirable to conduct the operation
under pressure, in which case a closed vessel must be employed, and in any case if
found advisable such operation may be carried on under varying conditions of
temperature.
Dotad this 10th daye of Antoba 1007

page_text: Improvements in Obtaining Gold and Silver from Ores and other
Compounds.
We, JOHN STEWART MAC ARTHUR, Analytical Chemist, of 15 Princes Street,
Pollokshields, in the County of Renfrew, North Britain, ROBERT
WARDROP
FORREST, M.D. and WILLIAM FORREST, M.B. both of 319 Crown Street,
Glasgow, in the County of Lanark, North Britain, 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, that is
to say :-
This Invention has principally for its object the obtaining of gold from its ores
or other compounds, but it is also applicable for obtaining silver from its ores or
compounds; and it comprises an improved process which whilst applicable to ores
or compounds generally is effectual with ores and compounds from which gold or
silver have hitherto not been easily obtainable because of the presence of various
other metals or their compounds or because of the physical or chemical condition
of the gold or silver in the ores or compounds.
In carrying out the Invention the ore or other compound in a powdered state
is treated with a solution containing cyanogen or cyanide (such as cyanide of
potassium, or of sodium, or of calcium) or other substance or compound containing
or yielding cyanogen. In practice we find the best results are obtained with a
very dilute solution, or a solution containing or yielding an extremely small
quantity of cyanogen or a cyanide, such dilute solution having a selective action
such as to dissolve the gold or silver in preference to the baser metals. In
preparing the solution we proportion the cyanogen to the quantity of gold or
silver or gold and silver estimated by assay or otherwise to be in the ore or
compound under treatment, the quantity of a cyanide or cyanogen-yielding
substance or compound being reckoned according to its cyanogen. We mix the
powdered ore or compound with the solution in a vessel made of or lined with
wood or any other convenient material not appreciably acted on by the solution.
The process is expedited by stirring the mixture of ore and solution intermittently
or continuously, for which purpose any convenient mechanical agitator may be
fitted to the vessel. When all or nearly all the gold or silver is dissolved the
solution is drawn off from the ore or undissolved residue, and is treated in any
suitable known way, as for example with zinc, for recovering the gold and silver.
The residuary cyanogen compounds may also be treated by known means for
regeneration or reconversion into a condition in which they can be used for
treating fresh charges of ores or compounds.
Any cyanide soluble in water may be used such as ammonium, barium, calcium,
potassium, or sodium cyanide, or a mixture of any two or more of them. Or any
mixture of materials may be taken which will by mutual action form cyanogen or a
substance or substances containing or yielding cyanogen.
In dealing with ores or compounds containing, per ton, twenty ounces or less of
gold, or silver, or gold and silver, we generally use a quantity of cyanide, the
cyanogen of which is equal in weight to from one to four parts in every thousand parts
of the ore or compound, and we dissolve the cyanide in a quantity of water of about
half the weight of the ore. In the case of richer ores or compounds, whilst
increasing the quantity of cyanide to suit the greater quantity of gold or silver we
also increase the quantity of water so as to keep the solution dilute. In using free
cyanogen, the cyanogen obtained as a gas in any well known way is led into water
to form the solution to be used in our process; or any suitable known mode of
setting cyanogen free in solution may be employed.

page_text: In some circumstances it may be found desirable to conduct the operation under
pressure in a closed vessel; and a higher than the ordinary temperature may be
used if found desirable.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed, we declare that we
do not claim generally the use of solutions of any strength but what we claim is :-
1. The process of obtaining gold and silver from ores and other compounds,
consisting in dissolving them out by treating the powdered ore or compound with a
dilute solution containing cyanogen or a cyanide or cyanogen-yielding substance,
substantially as hereinbefore described, and subject to the above disclaiming note.
2. The process of obtaining gold and silver from ores and other compounds,
consisting in dissolving them out by treating the powdered ore or compound with a
dilute solution containing a quantity of cyanogen or a cyanide or cyanogen-yielding
substance, the cyanogen of which is proportioned to the gold or silver or gold and
silver, substantially as herein before described.
ALLISON BROS.,
Agents for the Applicants.

page_text: We, JOHN STEWART MAC ARTHUR, Analytical Chemist, of 15 Princes Street, Pollok-
shields, in the County of Renfrew, North Britain, ROBERT WARDROP FORREST, M.D.,
and WILLIAM FORREST, M.B., both of 319 Crown Street, Glasgow, in the County of
Lanark, North Britain, do hereby declare the nature of this invention to bo as
follows:-
This invention has principally for its object the obtaining of gold from its ores or
other compounds, but it is also applicable for obtaining silver from its ores or com-
pounds, and it comprises an improved process which whilst applicable to ores or
compounds generally is effectual with ores and compounds from which gold or silver
have hitherto not been easily obtainable.
In carrying out the invention the ore or other compound in a powdered state is
treated with a solution containing cyanogen or a cyanide (such as the cyanides of
potassium, sodium or ammonium) or other substance or compound containing or
yielding cyanogen, till all or nearly all of the gold and the silver are dissolved; the
operation being conducted in a wooden vessel or a vessel made of or lined with a
material not acted on to any considerable extent by the solution or substances con-
tained therein. The solution is then drawn off and the metal or metals are recovered
by any suitable process; and the cyanogen, cyanide or substance containing or yielding
cyanogen may be regenerated. The cyanogen or substance containing or yielding
cyanogen may be used as such, or such materials may be taken as will by mutual
action form cyanogen or substances containing or yielding same.
Under certain circumstances it may be found desirable to conduct the operation
under pressure, in which case a closed vessel must be employed, and in any case if
found advisable such operation may be carried on under varying conditions of
temperature.
ALLISON BROS.,
Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements in Obtaining Gold and Silver from Ores and other
Compounds.
We, JOHN STEWART MACARTHUR, Analytical Chemist, of 15 Princes Street, Pollok-
shields, in the County of Renfrew, North Britain, ROBERT WARDROP FORREST, M.D.
and WILLIAM FORREST, M.B. both of 319 Crown Street, Glasgow, in the County of
Lanark, North Britain, 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 5
and by the following statement, that is to say :-
This Invention has principally for its object the obtaining of gold from its ores or
other compounds, but it is also applicable for obtaining silver from its ores or com-
pounds; and it comprises an improved process which whilst applicable to ores or
compounds generally is effectual with ores and compounds from which gold or silver 1
have hitherto not been easily obtainable because of the presence of various other metals
or their compounds or because of the physical or chemical condition of the gold or
silver in the ores or compounds.
In carrying out the Invention the ore or other compound in a powdered state is
treated with a solution containing cyanogen or cyanide (such as cyanide of potassium,
or of sodium, or of calcium) or other substance or compound containing or yielding
cyanogen. In practice we find the best results are obtained with a very dilute
solution, or a solution containing or yielding an extremely small quantity of cyanogen
or a cyanide, such dilute solution having a selective action such as to dissolve the
gold or silver in preference to the baser metals. In preparing the solution we pro-
portion the cyanogen to the quantity of gold or silver or gold and silver estimated by
assay or otherwise to be in the ore or compound under treatment, the quantity of a
cyanide or cyanogen-yielding substance or compound being reckoned according to its
cyanogen. We mix the powdered ore or compound with the solution in a vessel
made of or lined with wood or any other convenient material not appreciably acted on
by the solution. The process is expedited by stirring the mixture of ore and solution
intermittently or continuously, for which purpose any convenient mechanical agitator
may be fitted to the vessel. When all or nearly all the gold or silver is dissolved
the solution is drawn off from the ore or undissolved residue, and is treated in any
suitable known way, as for example with zinc, for recovering the gold and silver.
The residuary cyanogen compounds may also be treated by known means for
regeneration or reconversion into a condition in which they can be used for treating
fresh charges of ores or compounds.
Any cyanide soluble in water may be used such as ammonium, barium, calcium,
potassium, or sodium cyanide, or a mixture of any two or more of them. Or any
mixture of materials may be taken which will by mutual action form cyanogen or a
substance or substances containing or yielding cyanogen.

page_text: In dealing with ores or compounds containing, per ton, twenty ounces or less of
gold, or silver, or gold and silver, we generally use a quantity of cyanide, the cyanogen
of which is equal in weight to from one to four parts in every thousand parts of the
ore or compound, and we dissolve the cyanide in a quantity of water of about half
the weight of the ore.. In the case of richer ores or compounds, whilst increasing the
quantity of cyanide to suit the greater quantity of gold or silver we also increase
the quantity of water so as to keep the solution dilute. In using free cyanogen,
the cyanogen obtained as a gas in any well known way is led into water to form the
solution to be used in our process; or any suitable known mode of setting cyanogen
free in solution may be employed.
In some circumstances it may be found desirable to conduct the operation under
pressure in a closed vessel; and a higher than the ordinary temperature may be used
if found desirable.
Having now particularly described and ascertained the nature of our said
Invention and in what manner the same is to be performed, we declare that what
we claim is :-
1. The process of obtaining gold and silver from ores and other compounds, con-
sisting in dissolving them out by treating the powdered ore or compound with a
solution containing cyanogen or a cyanide or cyanogen-yielding substance, substantially
as hereinbefore described.
2. The process of obtaining gold and silver from ores and other compounds, con-
sisting in dissolving them out by treating the powdered ore or compound with a
dilute solution containing a quantity of cyanogen or a cyanide or cyanogen-yielding
substance, the cyanogen of which is proportioned to the gold or silver or gold and
silver, substantially as hereinbefore described.
Dated this 16th day of July 1888
ALLISON BROS.,
Agents for the Applicants.