Improved Method for the Extraction of Metals from their Ores.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improved Method for the Extraction of Metals from their Ores.
I, EMILE BOHON, of 81, Rue de Piennes, Cureghem, near Brussels, Belgium,
Engineer, do hereby declare the nature of this invention to be as follows:-
The object of the present invention consists in a method for the extraction of
metals, and particularly of precious metals, from metallic ores, or from the ores
which contain the said precious metals.
The first operation to be performed consists in finely pulverizing the ore
either dry or mixed with a small quantity of water whilst passing it through
a sieve. Afterwards the crushed ore is treated by a new method of amalgama-
tion and of cyanide treatment effected at the same time. Whilst the mercury is
acting directly, in the known manner, upon the ore, the cyanide of potassium
dissolves the small particles of gold and silver which by reason of their fineness
escape the direct amalgamation. The cyanides of precious metals thus formed
will be, in their turn, decomposed from their formation by the mercury which
takes up the precious metals that have become liberated. For that purpose, the
ore is mixed with a suitable quantity of mercury, of cyanide of potassium, and
of materials which should be chosen in accordance with the composition of the
ores, to prevent the decomposition of the cyanide of potassium. During the
mixing the materials are moistened with a certain quantity of solution of cyanide
of potassium until the mixture has been transformed into an almost liquid
paste. Afterwards the amalgam is separated from the residues which are then
washed in a bath of diluted cyanide of potassium.
In order to separate the precious metals from the amalgam thus obtained,
this latter is treated, after it has been concentrated hot by one pressure, with
nitric acid, which will separate the silver and the mercury. The remaining
precious metals, such as gold and platinum fall to the bottom of the receptacle,
whilst the silver is precipitated in the solution drawn off by means of any
suitable method of precipitation.
The concentration and the enrichment may be effected by any mechanical means
suitable for the mineral.
Another essential feature in my improved method is the formation of soluble
sulphides in the minerals treated, a formation which may be brought about
directly or after the hereinabove mentioned concentration, and in any well
known manner in common use.
If now the product thus obtained be first heated, and then thrown into water,
it will divide into two parts one of which will lodge upon the bottom, whilst
the other is dissolved in the water or remains in suspension in it. The greater
part of the metals and particularly of precious metals can be precipitated in
this bath, and that by the addition of acids or of earthy alkalines or of their salts

page_text: when these, in presence of metallic salts in solution, are easily decomposed in
such a manner that the precipitating bases become free.
The invention consists in the production of this precipitation, either by
means of finely divided organic matters which have been previously transformed,
or by the above mentioned bath, into a paste, either by means of natural oxida-
tion materials, or ones artificially prepared, respectively by means of chloride
of ammonia.
The production of sulphides and the subsequent precipitation places the
minerals in a condition which admits of the easy and complete extraction of the
inferior metals, and that in any well known and suitable manner.
As regards the precious metals, they are rendered free by the herein before
described operations, and followed by a roasting at a low temperature. The
fixed residues as well as the products of the precipitation should be finally
treated in accordance with the method of amalgamation and of cyanide treatment
hereinabove mentioned.
J. P. BAYLY,
18, Fulham Place, London, W., Agent for the Applicant.
I, EMILE BOON, of 81, Rue de Piennes, Cureghem, near Brussels, Belgium,
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:-
The subject of the present invention consists in a process for the extraction
of metals, and more especially of precious metals from the metallic ores, or
from the ores' which contain these precious metals.
The first operation to be performed consists in finely crushing or disintegrat-
ing the ores, either dry, or else mixed with a small quantity of water whilst pass-
ing it to the sieve. Afterwards the sifted ore is treated by means of a new
amalgamation process which consists essentially in an amalgamation and in
a cyanization effected at the same time. Whilst the mercury or quicksilver is
acting directly upon the ore in the well known manner, the cyanide of potassium
dissolves the five particles of gold and of silver which, by reason of their fine-
ness, escape the direct amalgamation. The cyanides of precious metals formed,
in this manner will be in their turn decomposed from their formation by the
mercury or quicksilver which takes up the precious metals that have become
free. With this object the ore is mixed with a sufficient quantity of mercury
or quicksilver, of cyanide of potassium, and of substances which should be chosen
in accordance with the composition of the ore, to prevent the decomposition of
the cyanide of potassium. These substances are those usually employed for
facilitating the amalgamation according to the processes at present known; for
example for easily reduced ores 200 gr. of sea salt and 200 gr. of lime, per ton
of ore, may be employed.
1
During the operation the materials are moistened with a certain quantity of
a solution of cyanide of potassium until such time as this mixture is transformed
into an almost liquid paste. Afterwards the amalgam is separated from the
residuums which are then washed in a diluted bath of cyanide of potassium.

page_text: in order to enect the separation or the precious metals from the amalgani which
has been thus obtained, this latter is treated, after its concentration performed
whilst hot by pressure, with nitric acid, which will dissolve the silver and the
quicksilver or mercury. The precious metals remaining such as the gold or
the platinum fall to the bottom of the receptacle, whilst on the contrary the
silver is precipitated in the solution, by means of any suitable method of pre-
cipitation.
The concentration or the enrichment may be effected by any mechanical means
suitable to the ore.
Another essential point in my improved process is the formation of soluble
sulpho-salts in the ores treated, formation which may take place either before
or after the concentration hereinabove mentioned, and that in any suitable
manner such as is ordinarily employed.
The said sulphurization is obtained by smelting the material together with a
suitable "Hux" capable of producing alkaline sulphate and an excess of sulphur
under the influence of heat.
If now the sulphurized product be thrown into water, it will separate into two
parts the one of which will be deposited on the bottom whilst the other (especially
precious metals) will be dissolved in the water or will remain in suspension
therein.
The greater portion of the metals, and more especially of the precious metals
thus dissolved or in suspension in the solution may be precipitated by the addi-
tion of acids or of earthy alkaline bases or else of their salts, which are easily
decomposed in presence of the metallic sulphate in solution.
The formation of sulphates and the subsequent precipitation place the ore in
such a condition that the complete extraction of the inferior metals will be
rendered easily possible.
As regards the precious metals, they have been separated by the above indi-
cated precipitation. After heating them at a low temperature. The fixed resi-
duums as also the products of the precipitation will be finally treated in accord-
ance with the process of amalgamation and of cyanization hereinabove described.
The sulphurizing fusion or melting is a disaggregation which is exclusively
applicable to substances containing metals of the arsenic group, and the object
of which is to convert these elements in soluble sulpho-salts.
Applicant obtains this result in smelting the matters with ten per cent. of its
weight of a flux capable of producing alkaline sulphuret and an excess of sulphur
under the influence of heat. The flux serves to produce the fusion of the
materials by the modification of their composition. The amount of flux employed
varies in accordance with the nature of the material to be treated; ordinarily
I employ 10 per cent. of the weight of said materials.
As a flux I may employ alkaline sulphurets, a mixture of sulphur and sodium
carbonate, carbon and sodium sulphate, sodium hyposulphite, or the like.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. The new process for the extraction of metals from their ores, consisting
in the amalgamation and the cyanization simultaneously of the precious metals
contained in the ores, these precious metals having been freed by a previous
treatment of the ores, and the said amalgamation being capable of being accele-
rated by means of suitable substances, such as easily reducible ores, substantially
as hereinbefore described.
2. The new process for the extraction of metals from their ores, consisting in
the amalgamation and the cyanization simultaneously of the precious metals
contained in the ores and freed by a previous treatment of these ores, in the extrac-
tion of the said precious metals from their amalgams by treating these latter
with nitric acid and by heating them at the same time, which admits of the

page_text: greater part of the precious metals being obtained, such as the gold, the platinum
ctc., in a pure condition and in the form of fixed residuums whilst the silver can
be precipitated in the solution.
Dated this 20th day of March 1899.
J. P: BAYLY,
18, Fulham Place, London, W., Agent for the Applicant.