Improvements in the Extraction of Gold and Silver from Ores or Compounds Containing the same and in Solvents for such Metals.
Year: 1887

page_text: Date of Application, 10th Dec., 1887
Complete Specification Left, 10th Oct., 1888
Complete Specification Accepted, 10th Dec., 1888
REDVE
Improvements in the Extraction of Gold and Silver from Ores
or Compounds Containing the same and in Solvents for such
Metals.
I, ALEXANDER PARKES, of 8 Chancellor Road, Dulwich, in the County of Surrey
Gentleman, do hereby declare the nature of this invention to be as follows:-
This invention relates to the treatment of auriferous and argentiferous ores or
compounds with solvents for the purpose of separating and collecting the gold and
silver contained therein. The invention further relates to solvents for such metals,
when combined or in a pure unalloyed state.
In treating ores containing gold or containing both gold and silver, I crush or
granulate the ore and in this condition submit it to the action of a solvent consisting
of a mixture (1) of bromine, cyanide of potassium and dilute chromic acid; or (2)
of fluorine, cyanide of potassium and dilute chromic acid; or (3) of bromine, chloro-
cyanide of potassium and water; or (4) of bromine and dilute hydrochloric, nitric,
sulphuric or chlorochromic acid; or (5) of bromine, chlorine and water; or (6) of
bromine (or fluorine), alcohol and water. Whilst the ore is in the presence of the
solvent, I prefer to subject the mixture to the action of steam under pressure for the
purpose of expediting the solution of the precious metals the mixture of ore and
solvent being at the same time maintained in a state of agitation. The solvent con-
taining the precious metals is then washed out of the ore and is treated by any
known method for the separation and recovery of the gold and silver (if any) held in
solution in the solvent. When the solvent employed consists of bromine, cyanide of
potassium and dilute chromic acid, or contains bromine and chlorocyanide of potassium,
the addition of bromine in excess may be employed for the purpose of precipitating
the silver contained in the solution; or cyanide or chlorocyanide of potassium may be
added in excess, and the gold precipitated.
In the ordinary treatment of gold ores with chlorine and without acid, the appli-
cation of steam under pressure in the manner herein before described may be employed
with advantage, and the solution of the gold expedited; but a still more active effect
is produced by employing bromine or fluorine in conjunction with chlorine.

page_text: The ore may or may not be calcined before treatment with one or other of the
solvents described; preliminary calcination, although in many instances advantageous,
not being essential to the success of my invention.
The solvents hereinbefore described, whether diluted or undiluted, may be employed
for rapidly dissolving the precious metals, when in a pure state or when in combination
with one another.
Dated this 10th dox of Davantia 1997
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C.,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Extraction of Gold and Silver from Ores
or Compounds Containing the same and in Solvents for such
Metals.
I, ALEXANDER PARKES, of 8, Chancellor Road, Dulwich, in the County of Surrey,
Gentleman, 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 the treatment of auriferous ores or compounds with
solvents for the purpose of separating and collecting the gold and silver contained
therein. The invention further relates to solvents for such metals when combined or
in an alloyed or unalloyed state.
In treating ores containing gold or containing both gold and silver, I crush or
granulate the ore, and in this condition submit it to the action of a solvent consisting
of one of the following mixtures, that is to say:-
1. Bromine, cyanide of potassium and dilute chromic acid, combined in the following
proportions:-
:-
4 lbs. Bromine, or an equivalent weight of a salt of bromine, such as crude
bromide of sodium or bromine dissolved in an alkali;
1 lb. cyanide of potassium or of sodium or other cyanide ;
1 lb. chromic acid, or bichromate of potash and sulphuric acid in equivalent
proportions:
40 gallons of water.

page_text: 2. Fluorine, cyanide of potassium and dilute chromic acid, combined in the following
proportions -
2 lbs. Fluorine, or hydrofluoric acid, or fluoride of calcium, sodium or other
compound from which fluorine can be evolved;
4 lbs. chromic acid or its equivalent (as stated in No. 1):
2 lbs. cyanide of potassium, or other cyanide.
40 gallons of water.
3. Bromine, chlorocyanide of potassium and water, combined in the following
proportions:-
3 lbs. Bromine or its equivalent (as stated in No. 1);
2 lbs. cyanide of potassium, or other cyanide
2 lbs. hypochlorite of soda or of lime or liquid chlorine or a soluble chloride salt
saturated with chlorine in equivalent quantities ;
40 gallons of water.
For the third of the above-mentioned ingredients, 5 lbs. of hydrochloric acid may
be substituted.
4. Bromine and dilute hydrochloric, nitric, sulphuric or chlorochromic acid,
combined in the following proportions:
:-
5 lbs. Bromine or its equivalent (as stated in No. 1) ;
20 lbs. hydrochloric acid (or a chloride salt and sulphuric acid yielding that
quantity of acid) or nitric acid (or a nitrate and sulphuric acid yielding that
quantity of nitric acid) or sulphuric acid;
40 gallons of water.
For the second of the above-mentioned ingredients, 1 lb. of chlorochromic acid and
10 lbs. of hydrochloric acid may be substituted.
5. Bromine, chlorine and dilute sulphuric or other acid, combined in the following
proportions:-
3 lbs. Bromine or its equivalent (as stated in No. 1);
1 lb. liquid chlorine;
10 lbs. sulphuric, hydrochloric or nitric acid;
40 gallons of water.
For the sulphuric acid specified in the above combination there may be substituted
an equivalent quantity of persulphate of iron or bisulphate of soda or other sulphate
containing sulphuric acid in excess.
Or alternatively
:-
4 lbs. Bromine or its equivalent (as stated in No. 1) :
10 lbs. water saturated with chlorine or an aqueous solution of a chloride salt,
such as of sodium, potassium, ammonium, calcium, magnesium, iron, lead,
mercury saturated with chlorine;
10 lbs. sulphuric, hydrochloric or nitric acid :
40 gallons of water.
For the second of the above-mentioned ingredients there may be substituted 4 lbs.
of hypochlorite of soda or its equivalent (as stated in No. 3).
6. Bromine (or fluorine), alcohol and dilute sulphuric or other acid, combined in the
following proportions :-
5 lbs. Bromine or its equivalent (as stated in No. 1);
2 lbs. spirits of wine, methylated or other spirit :
10 lbs. sulphuric, hydrochloric or nitric acid;
40 gallons of water.
For the first of the above-mentioned ingredients, 10 lbs. of bifluorhydrate or
irifluorhydrate of potassium, or a suitable soluble salt of fluorine from which this
cleinent can be obtained by electrolysis or otherwise, may be employed; the water
being at the same time acidified. The use of sulphuric or other mineral acid is not
essential with solvents Nos. 5 and 6 unless a hypochlorite be employed but I prefer
to add acid with a view to expediting the action.
Each of the foregoing mixtures is designed for use with one ton of ore; but the

page_text: quantity will necessarily vary with different descriptions of ore. The proportions of
the ingredients specified in the foregoing illustrations may also be varied within
certain limits, and those most appropriate determined by experiment with the particular
kind of ore or compound to be treated.
Whilst the ore is in the presence of the solvent, I prefer to subject the mixture to
the action of steam under pressure, for the purpose of expediting the solution of the
precious metals; the mixture of ore and solvent being at the same time maintained
in a state of agitation. This may be effected in a wooden or wood-lined vessel,
stoutly hooped with or enclosed in metal. The solvent containing the precious metals
is then washed out of the ore, and having been filtered is treated by any known
method for the separation and recovery of the gold and silver (if any) hield in solution
in the solverit.
When the solvent employed consists of bromine, cyanide of potassium and dilute
chromic acid, or contains bromine and chlorocyanide of potassium, the addition of
bromine in excess may be employed for the purpose of precipitating the silver contained
in the solution; or cyanide or chlorocyanide of potassium may be added in excess,
and the gold precipitated.
In the ordinary treatment of gold ores with chlorine and without acid, the appli-
cation of steam under pressure in the manner herein before described
may be
employed with advantage and the solution of the gold expedited; but a still more
active effect is produced by employing bromine or fluorine in conjunction with
chlorine.
The ore may or may not be calcined before treatment with one or other of the solvents
described preliminary calcination, although in many instances advantageous, not
being essential to the success of my invention.
The solvents herein before described, whether diluted or undiluted, may be employed
for rapidly dissolving the precious metals when in a pure state or when in combination
with one another or otherwise alloyed.
Having thus particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I claim
:-
1st: In the extraction of gold and silver from ores or compounds containing the
same, the employment, as a solvent for such metals, of "bromine, cyanide of
potassium and dilute chromic acid, combined substantially in the proportions
herein set forth.
2ndly In the extraction of gold and silver from ores or compounds containing
the same, the employment, as a solvent for such metals, of fluorine, cyanide of
potassium and dilute chronic acid, combined substantially in the proportions herein
set forth.
:-
3rdly In the extraction of gold and silver from ores or compounds containing
the same, the employment as a solvent for such metals, of bromine, chlorocyanide
of potassium and water, combined substantially in the proportions herein set forth.
thly In the extraction of gold and silver from ores or compounds containing
the same, the employment, as a solvent for such metals, of bromine, dilute hydro-
chloric, nitric or sulphuric acid (or chlorochromic and hydrochloric acids), combined
substantially in the proportions herein set forth.
5thly In the extraction of gold and silver from ores or compounds containing
the same, the employment, as a solvent for such metals, of bromine and liquid chlorine,
combined substantially in the proportions herein set forth and used in conjunction
with dilute acid or otherwise.
6thly -In the extraction of gold and silver from ores or compounds containing
the same, the employment, as a solvent for such metals, of bromine, water saturated
with chlorine or its equivalent as specified, or hypochlorite of soda or its equivalent
as specified, and dilute sulphuric, nitric or hydrochloric acid, combined substantially
in the proportions herein set forth.
7thly In the extraction of gold and silver from ores or compounds containing

page_text: the same, the employment, as a solvent for such metals, of bromine or fluorine or its
equivalent as specified and alcohol, combined substantially in the proportions herein
set forth and used in conjunction with dilute acid or otherwise.
Sthly In the extraction of gold and silver from ores or compounds by means of
solvents of the kinds herein specified, subjecting the mixture of ore and solvent to the
action of steam under pressure and agitating the same, substantially as and for the
purposes herein described.
9thly In the extraction of gold and silver from ores or compounds by means of
bromine or chlorine, subjecting the ore whilst in the presence of such agent to the
action of steam under pressure and agitating the mixture, substantially as and for the
purposes herein described.
10thly In the extraction of gold and silver from ores or compounds by means of
bromine in combination with chlorine, or bromine and fluorine, or chlorine and
fluorine, subjecting the ore whilst in the presence of either of such compound agents
to the action of steam under pressure and agitating the mixture, substantially as and
for the purposes herein described.
11thly For rapidly dissolving gold or silver or alloys of gold and silver, the
employment of the several solvents composed substantially of the respective com-
binations of agents herein specified, and whether diluted or undiluted.
Dated this 10th day of October 1888
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C.,
Agent for the Applicant.