An Improved Process for the Extraction of Precious Metals from their Ores and Compounds.
Year: 1895

page_text: Date of Application, 20th Aug., 1895
Complete Specification Left, 19th May, 1896-Accepted, 20th June, 1896
An Improved Process for the Extraction of Precious Metals from
their Ores and Compounds.
I, WALTER HAWEIS JAMES, of 5 Lexham Gardens, in the County of London,
Captain in Reserve of Officers, late Royal Engineers, do hereby declare the nature
of this invention to be as follows:-
This invention relates to an improved process for the treatment of auriferous
and argentiferous ores and compounds for the purpose of extracting the gold and
silver therefrom by means of a solution that will act as a solvent on the gold and
silver.
When a solution of potassium cyanide is employed in a well known manner for
extracting gold the reaction that takes place is, according to Elsner's equation,
as follows:-
By this process the time taken to effect a proper extraction of the gold is
very considerable the oxygen necessary for the operation being obtained from
the air.
According to my invention I propose to greatly hasten the process by the use
with the cyanide or solvent solution of a substance hereinafter mentioned which
supplies the requisite quantity of oxygen without depending upon the oxygen of
the air and which, besides shortening the process, keeps the solution in a
better condition for extracting the gold and considerably augments the selective
action by which the potassium or other cyanide salt attacks tbe gold in preference
to the baser metals.
The substance that 1 employ with the cyanide solution is peroxide of hydrogen
which is used in such proportion relatively to the cyanide salt in the solution as
will enable the requisite amount of oxygen to be supplied for bringing about the
desired result.
It will be found advantageous to render the ores or compounds alkaline before
subjecting them to treatment with
my solution.
For
The peroxide of hydrogen may be prepared in any suitable manner.
instance a brisk stream of carbonic anhydride may be passed through water to
which barium peroxide is added from time to time, peroxide of hydrogen is formed
and goes into solution, barium carbonate being precipitated.
1 prefer that the peroxide of hydrogen and water should be in about the
proportion of 10 volumes of peroxide to 10 volumes of water; this proportion
may however be varied to meet the requirements of individual cases.
Although I have described my invention more particularly with reference to the
extraction of gold, it can equally well be employed in an analogous manner for
the extraction of silver and other precious metals.
Dated this 20th day of August 1895.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.

page_text: An Improved Process for the Extraction of Precious Metals from
their Ores and Compounds.
I, WALTER HAWEIS JAMES, of 5 Lexham Gardens, in the County of London,
Captain in Reserve of Officers, late Royal Engineere, 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 an improved process for the treatment of auriferous
and argentiferous ores and compounds for the purpose of extracting.the gold and
silver therefrom by means of a solution that will act as a solvent of the gold
and silver.
When a solution of potassium cyanide is employed in a well known manner for
extracting gold for example from its ores or compounds the reaction that takes
place is, according to Elsner's equation, as follows:-
2 Au + 4 KCy + 0 + H¸O = 2 AuKCy, + 2 KOH.
By this process the time taken to effect a proper extraction of the gold is
very considerable, the oxygen necessary for the operation being obtained from
the air.
According to my invention I propose to greatly hasten the process by the use
with the cyanide or solvent solution of a substance hereinafter mentioned which
supplies the requisite quantity of oxygen in a readily available form and so avoids
having to depend upon the oxygen of the air. The said substance moreover keeps
the solution in a better condition for extracting the gold and considerably
augments the selective action by which the potassium or other cyanide salt
attacks the gold in preference to the baser metals in the ore or compound under
treatment.
The substance that I employ with the cyanide solution/is a solution of peroxide
of hydrogen which is used in such proportion relatively to the cyanide solution
as will enable the requisite amount of oxygen to be supplied for bringing about the
desired result.
It will be found advantageous to render the ores or compounds alkaline before
subjecting them to treatment with my solution.
The peroxide of hydrogen may be prepared in any suitable manner, for instance
by passing a brisk stream of carbonic anhydride through water to which barium
peroxide is added from time to time. The peroxide of hydrogen thus formed goes
into solution and barium carbonate is precipitated.
The strength of the solution of peroxide of hydrogen and water that I prefer to
use in my improved process is one containing about 10 volumes of peroxide to
100 volumes of water; this proportion may however be varied to meet the
requirements of individual cases. The quantity of such solution to be added to
the cyanide solution will depend upon the character of the ore or compound to be
treated and will be determined by experiment in each particular case in order to
get the best results.
I have described my invention more particularly with reference to the extraction
of gold, but it can equally well be employed in an analogous manner for the
extraction of silver and other precious metals.
1
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
claim is :-
The improved process for the extraction of precious metals from their ores or

page_text: compounds consisting in the use with a cyanide solvent of a solution of peroxide of
hydrogen, substantially as described and for the purpose specified.
Dated this 19th day of May 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicant.