Improvements in the Extraction of Precious Metals from their Ores or from Compounds containing the same.
Year: 1895

page_text: Date of Application, 25th Feb., 1895
Complete Specification Left, 25th Nov., 1895-Accepted, 25th Feb., 1896
PROVISIONAL SPECIFICATION.
Improvements in the Extraction of Precious Metals from their Ores
or from Compounds containing the same.
I, JAMES MACTEAR, of 28, Victoria Street, Westminster, Chemical Expert and
Engineer, do hereby declare the nature of the said invention to be as follows:-
This invention relates to improvements in the extraction of precious metals from
their ores or compounds containing the same by the use of a solvent having a more
economical and advantageous action than those in present use.
The invention consists in the use for the purpose of the invention of a solution
containing cyanuric acid or a cyanurate and cyanide of potassium or other cyanide
or cyanogen compound from which free hydrocyanic acid can be liberated by the
addition of an acid or acid salt or other substance or compound.
The cyanuric acid may be added as such or in the form of a cyanurate, or it may
be produced directly in the solution when required, by well known means, such as
the action of a hypochlorite or hypobromite upon hydrocyanic acid or a cyanide
-and this latter mode I prefer to employ. Hypochlorite of lime or of soda or of
potash or the corresponding hypobromites are especially suitable for use in thus
producing the cyanuric acid.
The presence in such a solution of cyanuric acid free or combined renders the
action of such solution much more active as a solvent of the precious metals than
are solutions of cyanides alone, such as have hitherto been used; the rapidity of
the action of such a solution so containing cyanuric acid upon gold or silver is
such as to avoid to a very large extent the objectionable action of ordinary cyanide
solutions upon the base metal compounds commonly found in the ores or other
compounds containing the precious metals.
Tailings, concentrates and refractory ores generally are especially susceptible to
treatment by such a solution containing cyanuric acid.
Some of the advantages of the use of such a cyanuric-acid-containing-cyanide-
solution in comparison with alkaline cyanide solutions, such as have hitherto
been used, are that the action of the former upon the precious metals is much more
rapid than the action of the latter, with a given quantity of cyanogen in each
solution, and that a smaller quantity of cyanide is required to effect the extraction
of a given quantity of precious metal, other conditions being the same.
In the cases of ores carrying much silver as sulphide, it is best to have the
solution more alkaline than in the case of ores carrying only gold
and silver in the
metallic state.
ог
In carrying the invention into effect, I treat the ore or other compound in a
crushed or powdered condition to the action of the cyanuric-acid-containing-cyanide-
solution in suitable containing vessels, such as are usually employed in wet processes
of extracting the precious metals, and after separating the solution from the
residue by the usual methods of draining and washing, I separate the gold and
silver from the solution by any suitable methods.
Dated this 25th day of February 1895.
ог
DAY, DAVIES & HUNT,
321, High Holborn, London, W.C., Agents for the Applicant.

page_text: Improvements in the Extraction of Precious Metals from their Ores
or from Compounds containing the same.
1, JAMES MACTEAR, of 28, Victoria Street, Westminster, Chemical Expert and
Engineer, 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 extraction of precious metals from their ores or from
compounds containing the same by the use of a solvent having a more economical
and advantageous action than those in present use.
The invention consists in the use, for the purpose of the invention, of a solution
containing both cyanuric acid or a cyanurate and cyanide of potassium or other
cyanogen compound from which free hydrocyanic acid can be liberated by the
addition of an acid or acid salt or other substance or compound.
The proportionate quantity of the cyanuric acid relatively to that of the cyanide
present in the solution will depend to a large extent upon the physical condition of
the ore or compound under treatment, as, for example, in ores in which the gold
is fine and free, five parts of cyanuric acid to each one hundred parts of the cyanide
will be found to give good results, but, in some cases, even a less proportionate
quantity of the cyanuric acid may be used; while, with more refractory ores or
those in which the gold is coarser, a larger proportionate quantity of the cyanuric
acid may be used, but in very few cases will it be found necessary to use a greater
proportionate quantity than twenty five parts of the cyanuric acid to each
one hundred parts of the cyanide.
The cyanuric acid may be added as such or in the form of a cyanurate to the
cyanide or cyanogen compound solution, or it may be produced in the solution by
the action of a hypochlorite or hypobromite upon hydrocyanic acid or a cyanide,
and this latter mode I prefer to employ. Hypochlorite of lime or of soda or of
potash or the corresponding hypobromites are especially suitable for use in thus
producing the cyanuric acid.
The presence, in such a solution, of cyanuric acid free or combined renders the
action of such solution much more active as a solvent of the precious metals than
are solutions of cyanides or cyanogen compounds not containing cyanuric acid,
such as have hitherto been used: the action of such a solution containing cyanuric
acid upon gold or silver being also such as to avoid to a very large extent the
objectionable action of ordinary cyanide solutions (those not containing cyanuric
acid) upon the base metal compounds commonly found in the ores or other
compounds containing the precious metals, and which, hinders the obtainment of
the precious metals. Further advantages arising from the use of such a cyanuric-
acid-containing-cyanide-solution in comparison with cyanide solutions such as have
hitherto been used, are that the action of the former solution upon the precious
metals is much more rapid than that of the latter solutions with a given quantity
of cyanogen in each solution, and that a smaller quantity of cyanide is required to
effect the extraction of a given quantity of precious metal, other conditions being
the same.
Tailings, concentrates and refractory ores generally are especially susceptible to
treatment by such solution containing cyanuric acid.
In the case of ores carrying much silver as sulphide, it is best to have the
solution more alkaline than in the case of ores carrying only gold and silver in the
metallic state.
In carrying the invention into effect, I treat the ore or other compound in a
crushed or powdered condition to the action of the cyanuric-acid-containing-
cyanide-solution in suitable containing vessels such as are usually employed in wet

page_text: processes of extracting the precious metals, and after separating the solution from
the residue by the usual methods of draining and washing, 1 separate the gold or
silver from the solution by any suitable methods.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
:-
The extraction of precious metals from their ores or from compounds containing
the same, by the use of a solution of cyanide of potassium or other cyanide or
cyanogen compound of the nature aforesaid, containing cyanuric acid or a
cyanurate.
Dated this Olet dow of Nab 100-
DAY, DAVIES & HUNT,
321, High Holborn, London, Agents for the Applicant.