IMPROVED METHODS OR PROCESSES OF SEPARATING METALS AND METALLOIDS FROM THEIR ORES AND OTHER SUBSTANCES BY MEANS OF ELECTRICITY
Year: 1882

page_text: LETTERS PATENT to William Robert Lake of the firm of Haseltine Lake
& Co Patent Agents, Southampton Buildings, London, for an invention of
"IMPROVED METHODS OR PROCESSES OF SEPARATING METALS AND METALLOIDS
FROM THEIR ORES AND OTHER SUBSTANCES BY MEANS OF ELECTRICITY "
A communication from abroad by Eugenio Marchese, of Turin, Italy.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at the
Office of the Commissioners of Patents on the 19th April 1882.
WILLIAM ROBERT LAKE of the firm of Haseltine, Lake, & Co Patent Agents,
Southampton Buildings, London "IMPROVED METHODS OR PROCESSES OF
SEPARATING METALS AND METALLOIDS FROM THEIR ORES AND OTHER SUBSTANCES
BY MEANS OF ELECTRICITY "[A communication from abroad by Eugenio
Marchese, of Turin, Italy.]
It is well known that a liquid which is a conductor of electricity, if it is traversed
by a current of sufficient electro-motive force, is decomposed into two parts, one of
which goes to the negative electrode (acid or halogenous radical) and the other to
the positive electrode (basic and metallic radical)
It is also known that the acid radical of the electrolyte produces an oxidizing
action upon the plate of metal which serves as the negativo electrode which action
has for a long time been utilized in electro-metallurgy and recently for refining
copper and lead.
The principle which is not yet industrially applied, and which forms the
foundation of the present invention is that there is an oxidizing and reductive
action of the elements of a decomposed electrolyte upon all mineral substances,
when these substances (whether natural products or products of chemical or
metallurgical arts) are placed in the clectrolytic liquid in place of the ordinary
electrodes. The oxidizing action due to the electric current produces the direct
transformation of all, or a part of, the metals which it is desired to extract from
the material being treated, into electrolytic liquids (soluble salts).

page_text: The reductive action separates in its turn the metalloids of the metals contained
in the material being treated. At the same time that the electric current causes
the formation of the electrolytes in the manner already indicated, the same current
decomposes the electrolyte or electrolytes from which it is desired to obtain the
metal or metalloid.
The different special methods employed according to the said invention may be
Croused in the following sing
The mineral substance to be treated acting as the negative electrode. If it is
proposed to extract the only metal contained in a single mineral binary compound
it is sufficient to chose an electrolyte such that its acid radical combines chemically
with the metal forming a soluble salt and has no action upon the metalloid. This
soluble salt, which is formed in the bath by the decomposition of the electrolyte
by the current will be immediately decomposed by the same current provided the
latter has the necessary electro-motive force; the metal will be deposited at the
positive electrode; the acid radical will be restored at the negative electrode for
the successive-attack-of-the-mineral substance being treated. If the substance to
be treated is not a binary compound but multiple (n. metals + m. metalloids
either chemically or mechanically combined) all the metals can be extracted by
choosing the electrolyte in such a manner that its acid radical, while oxidizing the
said metals, forms the corresponding soluble salts and has no chemical action upon
the metalloids.
The separation of metals from electrolytes-thus-formed-takes place upon the
principle that for the decomposition of each electrolyte it is necessary to have a
current of a determined electro-motive force; and therefore the process should be
commenced by the decomposition of the electrolyte which requires the sinallest
difference of potential in the current, passing afterwards to the decomposition
respectively of those which require a greater and greater difference of potential.
The separation of metals may also be effected by choosing an electrolyte such
that the product of the chemical combination of its acid radical and the metals of
the substance being treated shall be soluble for the metal which it is desired to
extract and insoluble for the other metals. Or only one of the metals contained in
the substance to be treated may be transformed into an electrolyte, care being taken
to make use, in the bath, of saturated solutions of salts with a base of the metals
it is not desired to extract.
By this means it is possible to extract, one after another, all the metals
contained in the substance being treated. It is also possible, after submitting to
decomposition by the electric current the electrolytes of each metal, in cases where
their is industrial advantage, to employ them or sell them either directly or after
some previous preparation (concentration, crystallization or other treatment).
For this purpose it is necessary that the difference of potential of the current
should only be capable of decomposing the electrolyte employed at the commence-
ment of the operation, without decomposing any of the metallic electrolytes formed
afterwards. As for the metalloids which remain as such in the residues, they may
be used directly for industrial purposes; or else they may be transformed into
electrolytes by employing for the bath saturated solutions of all the salts corre-
sponding to the metals of the substance being treated, care being taken that the
electro-motive force of the current can only decompose the electrolyte which
has been introduced at the commencement of the operation without decomposing
any of the soluble salts contained in the bath.
Another method may be adopted which consists in the alternate oxidation of
the metals and metalloids which transforms them into soluble ternary substances
(electrolytic salts) upon which is effected the partial decomposition as indicated in
the preceding methods.

page_text: separation IS OUGANTIca of one or more metais from one or more meatIVIUS
substance to be treated is a binary body the separation is complete; the metal
remains in the residue and the metalloid combines with the basic radical of the
electrolyte adopted. The product of this combination may generally be collected
and utilized for industrial purposes. If the mineral substance is a multiple
compound, the products resulting from the combination of the basic radical of the
electrolyte with the metalloids will be utilized; but the metals which will be mixed
in the residue, in order that they may be separated, should be transported to
the negative electrode and submitted to the treatment indicated in the first series.
THIRD SERIES
The mineral substancos acting alternately as positive and negative electrodes.
The object of this operation is to transform into electrolytic salts all, or part of, tho
metal or metalloids which act as negative electrodes, and to collect the metalloids
at the substances which act as positive electrodes; for this purpose it is necessary
that the electro-motive force of the current should decompose the electrolytes put
in action at the commencement but not decompose the salts which result from the
oxidation of the substance acting as the negative electrode. This restriction is
necessary in order to avoid all deposit, at the positive electrode, of motal or metals
resulting from the decomposition of the metallic electrolytes of the bath. Tho
choice of the electrolyte or electrolytes which should form the bath and the
difference of potential of the electric current to be employed depend upon the
chemical composition of the mineral substance to be treated, they must therefore
vary for each particular case and it is impossible to determine them (a priori) in
this description. But whatever may be the chemical composition of the substance
to be treated the electrolytes to be decomposed by the electric current should
always be obtained by placing the substance to be treated so as to act instead of
the usual electrodes, and by the effect of the oxidizing or reductive action which
takes place at the electrodes by the decomposition of the electrolyte introduced
into the bath at the commencement of the operation.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said William Robert Lake in the Great Seal Patent Office on the
19th October 1882.
WILLIAM ROBERT LAKE, of the firm of Haseltine Lake, and Co Patent Agents,
Southampton Buildings, London, " IMPROVED METHODS OR PROCESSES OF
SEPARATING METALS AND METALLOIDS FROM THEIR ORES AND OTHER SUBSTANCES
"
BY MEANS OF ELECTRICITY.' A communication from abroad by Eugenio
Marchese, of Turin, Italy.
It is well known in science that a liquid which is a conductor of electricity, if it
is traversed by a current of sufficient electromotive force, is decomposed into two 1
_ parts, one of which goes to the negative electrodo (acid and halogenous radical)
and the other to-the-positive.clectrode (basic and metallic radical).
It is also known that the acid radical of the electrolyte-produces an oxidizing
action upon the plate of metal which serves as the negative electrode, which action
has for a long time been utilized in electro-metallurgy and recently for refining 1
copper and lead.
This invention is based upon the employment, as an electrode, of the ore or
other metalliferous substance-from-which it is desired to extract the metal or
metals, and upon the oxidizing or reductive action exerted upon-the-electrodes_by_
the components of an electrolyte which is decomposed by the electric current.
But the said invention comprises three different methods or processes; the first
when the ore or other substance to be treated is to act as the anode (positive
electrode or positive pole); the second when the ore or other substance to be
treated is to act as the kathode (negative electrode or negative pole); the third
when two ores or other substances to be treated are to act at the same time the
one as the anode and the other as the kathode.
When the ore or other substance to be treated serves as the anode (positive
electrode or positive pole), if it is desired to extract a single metal, it is only
necessary to choose an electrolyte whose acid radical will combine chemically with
the metal and will have no action upon the metalloid, By the action of the :
electric current the electrolyte is decomposed, its acid radical, which will be
produced upon the anode, will attach the ore or other substance constituting the
anode, and will form a soluble salt of the metal which is to be extracted; this salt
will be decomposed in its turn by the current, with a deposit of metal upon the
kathode and the return of the acid radical to the anode to successively attack the
material under treatment:
Assuming, for example, that galena composed of sulphur and lead is to be
treated, nitrate of lead is used as the electrolyte. In the vessel in which the
operation is to be effected are placed narrow boxes or compartments the lateral
walls of which are of cloth, and which are filled with galena in picces, grains or
slich, as it comes from the mine or other source. Upon the upper free surface of
the galena thus placed, metallic conducting bars are caused to bear; these bars
occupy the length of each of the boxes of galena, and are connected to the positive
pole of the source of electricity (dynamo-electric or other machine). The galena
contained in the said boxes will constitute in this manner the anode of the system.
Between the boxes of galena are suspended plates of lead or other suitable con-
ducting material, which plates are connected to the negative pole of the source of
clectricity and which will form the kathode. A solution of nitrate of lead is

page_text: introduced into the vessel until the level is a little below the upper surface of the
galena upon which the conducting bars bear. The electric current traverses tho
bath and decomposes the nitrate of lead. The lead deposits upon the kathode.
The acid radical (nitric acid + oxygen) forms at the same time upon the anode
(the galena); it attacks the galeua and reproduces nitrate of lead, and so on.
The
nitric acid does not attack the sulphur of the galena whilst there is lead to bo
attacked, the electro-motive force being maintained within the limits hereinafter
indicated. The sulphur, however, remains at the anode in the form of pure
sulphur (S).
If the galena is not pure but contains a small quantity of unattacked gangue or
vein-stone, the sulphur remains disseminated in the same, from which it can be
separated by distillation in the ordinary manner in which native sulphur is
separated from the gangue or vein-stone which accompanies it in sulphur ore. The
lead deposited upon the kathode in moro or less crystalline and adherent sheets is
collected from time to time so as to prevent its coming in contact with the galena
of the anode. It is washed, re-melted, or pressed.
The operation is effected in a similar inanner if acetate of lead is employed as
the electrolyte instead of nitrate of lead.
The number and dimensions of the vessels and of the boxes of galena forming
the anode which each vessel should contain are not determined by the chemical
reaction which takes place in the operation but by the conditions of the source of
electricity which is employed. The vessels must be arranged in tension as far as
is necessary to reduce the electromotive force to the number of volts or fractions of
volts necessary for the chemical reaction of the dissociation; and it is necessary
that the derived or branch circuits and the surfaces of the electrodes should be
such as to reduce the external resistance of the circuit to the quantity most
favorable to the best economical yield of the dynamo-electric machine employed.
Care must be taken in this operation to employ only the electromotive force
absolutely necessary for the reaction of dissociation, which force is generally
inferior to that which is required by the dissociation of salts of the same metal
previously held in solution. Because in the attack of the mineral anode a portion
of the electromotive force is furnished by this attack itself. And the production of
gas which causes polarization can therefore generally be avoided. To this end the
choice, for an initial electrolyte, of a soluble salt of the metal which it is desired to
extract (which may be a conductor of electricity) is preferable to the simple
acidification by the acid which will produce, the same salt by the action of the
electric current; because the salt will only be formed by the action of the acid by
means of the decomposition of the water with the liberation of the polarizing gas,
and, in certain cases, with the necessity for augmenting the electromotive force of
the current.
Copper ore or sulphuret of copper can be treated in a manner analogous to that
above described by taking for the electrolyte sulphate of copper; blende (sulphuret
of zinc) by taking for the electrolyte sulphate of zinc; pyrites (sulphuret of iron)
by taking for the electrolyte sulphate of iron; and all other ores and sulphuretted
products which are conductors of electricity by choosing a suitable electrolyte.
The metal will be obtained at the kathode and the sulphur will remain with the
residues at the anode and can be extracted by simple distillation.
If the sulphuretted ore is poor in metal and not a sufficiently good conductor of
electricity, it is necessary to commence with fusion of the raw ore, without roasting,
for the purposes of eliminating in the form of scoria or slag the non-metallic gangue
and of concentrating the metals and the sulphur in a mass from which the metal
and sulphur can be extracted as above described.
-
The indications given above in the treatment of galena with regard to the number
of vessels their arrangement in tension and in branch or derived circuits, the
employment of an electric current having an electromotive force which does not too
far exceed the force necessary for the chemical reaction of dissociation of the

page_text: substance to be treated, the choice of a soluble salt of the metal to be extracted as
the initial electrolyte to avoid polarization or an increase of electromotive force, the
concentration of ores which are not sufficiently good conductors (on account of the
too great proportion of non-metallic gangue which they contain) by fusion (without
roasting) which concentrates the sulphur and the metals into a product capable of
being treated by the improved process, are all applicable generally to other methods
of treating ores as hereinafter described.
If the mineral substance to be treated contains a number of inetals, the attack of
the substance is effected on the same principle, but the separation of the metals can
be effected by the application of different scientific principles.
Assuming the galena to be argentiferous, composed, for example, of sulphuret of
lead and sulphuret of silver (m Pb S + n Ag S).
The operation is effected as above described by taking for the initial electrolyto
nitrate of lead. All the lead is obtained upon the kathode, the silver is not
attacked and remains at the anode with the sulphur, the unattacked gangue, and
a small quantity of lead. According to the richness in silver of this residue,
depending upon the richness in silver of the galena under treatment, it may be
passed to a cupel, or subjected to fusion, after having separated the sulphur by
distillation.
The silver and the lead are, in these cases, separated according to the principle
of the formation of that compound which will liberate the most heat by its
formation. In presence of the acid radical (nitric acid plus oxygen) at the anode
-(argentiferous_galena), it is the lead which combines to form nitrate of lead, the
formation of which occasions more heat than that of nitrate-of-silver..
If desired, the lead can be separated from the silver by taking for the initial
electrolyte acetate of lead upon the principle that the acid radical of the electrolyte
employed cannot combine with one of the metals to be separated (silver).
In order to treat iron pyrites which contain more or less copper, sulphate of
copper can be used for the initial electrolyte. The pyrites to be treated are placed
as the anode, in the manner above indicated for the galena, and copper plates are
used as the kathode. By means of the electric current all the copper which the
pyrites contained is deposited at the kathode without any trace of iron.
If it is desired to extract part of the sulphate of iron which is produced in the
operation and which remains in solution in the bath in this case, when the bath
is saturated with sulphate of iron, the anodes of copper pyrites are withdrawn and
anodes of carbon are substituted for them, and the copper contained in the bath
is precipitated to the last trace. The sulphate of iron is then run into vessels to
crystallize, or it can be used directly if desired. Or the solution is still further
subjected to the action of the electric current, to obtain pure metallic iron and
sulphuric acid to be employed in the succeeding operations,
By this method all the copper contained in the copper pyrites is obtained in the
form of metallic copper, nearly the whole of the sulphur in the form of pure
sulphur (S) as a residue at the anode mixed with a small quantity of sulphuret
of iron, from which it is finally separated by distillation; and nearly the whole of
the iron is obtained in the form of sulphate of iron. The sulphur which is with-
drawn more than compensates for the value of the sulphuric acid employed to form
the sulphate of iron.
If it is not desired to convert the iron of the pyrites into sulphate, the operation
is continued indefinitely in the same bath, When the bath is saturated with
sulphate of iron, the iron of the pyrites is no longer attacked. By this method all
the copper which deposits on the kathode is extracted. The sulphuret of iron
remains at the anode, in addition to the sulphur corresponding to the sulphuret
of copper dissociated by the electrolysis. By a simple distillation the pure sulphur
can be obtained, leaving as a residue the sulphuret of iron which has not been
attacked in the operation of the electrolysis.

page_text: It is necessary, as above stated, in general that the electromotive force of the
current should slightly exceed that necessary for the chemical reaction of dissociation
in order not to oxidize the sulphur.
In the same manner ordinary chalcopyrites can be treated.
When the ore or other substance to be treated is employed as the kathode, the
operations are as follow, that is to say :-If it is desired to extract the metal
fron a metallic sulphuret or ore, for example, galena or chalcosine, and tho
sulphuretted hydrogen can be employed at the works, the operation is effected by
electrolysis, by placing the metallic sulphuret or ore as the kathode and employing
an unattackable anode, for example, conducting carbon. An electrolyte is used
the decomposition of which by the current will produce hydrogen at the kathode,
for example, sulphate of hydrogen, that is to say, water acidified by sulphuric
acid. By this arrangement the sulphur of the sulphurous ore will be converted
into sulphuretted hydrogen which will be in part collected and employed in the
form of gas, and will be partly decomposed with the production of sulphur. There
will remain upon the kathode the metallic copper.
If the sulphuretted ore contains a number of metals, only the desulphuration
is obtained; the metals will remain mixed upon the kathode. This mixture
should then be treated according to the first series of operations above described,
the said mixture serving as the anode.
In a similar manner to that in which the de-sulphuration of a sulphuretted ore
is obtained the dechloruration of a chloruretted ore (chloride of silver) can be
effected, or the de-oxidation (reduction) of an oxidized ore (protoxide of copper,
protoside of iron and the like).
In cases where the ores or metallic substances are to be used at the same time
one as the anode and the other as the kathode, I proceed as follows, that is to
EDY:-
If, for example iron pyrites and sulphuret of copper, or copper ore are to be
treated, and sulphuretted hydrogen can be employed at the works, the iron pyrites
can be made to serve as the anode, and the sulphuret of copper as the kathode.
In this arrangement the sulphur of the sulphuret of copper can bo utilized as
sulphuretted hydrogen and sulphur, the copper as metallic copper, the iron passing
in the form of sulphate of iron can be utilized in this state as hereinbeforo
indicated, and the sulphur which remains from the pyrites compensates for the
sulphuric acid employed to form sulphate of iron. The sulphate of iron may also
be decomposed by the electric current as above described.
Having thus fully described the said invention as communicated to me by my
Foreign correspondent and the manner of performing the same I wish it understood
that I Claim.
The new methods or processes for the application of the following principles of
electro-chemistry, that is to say:
First. The method or process above described for utilizing the oxidizing and
reductive action which is produced at the two electrodes by the decomposition of
an electrolyte for the separation of metallic sulphurets and other ores and products
of metallurgical and chemical operations, in which method or process these ores or
products are employed as the positive or the negative electrode, according as it is
desired to utilize the oxidizing or the reductive action upon the ore or product, by
which arrangement the electric current, in traversing the electrolytic bath, produces
first, the conversion, into a soluble salt, of the metal or metals contained in the
metallic sulphuret, ore or product from which it is desired to extract the metals
and metalloids, and second, the dissociation of the soluble salt thus produced, with
the deposition of the metal as above described.
Second. The improved methods or processes above described and based upon the
following principles, namely, first, the separation of metal contained in an electrolyte
by means of the specific difference in the electronfotive force which is necessary
for the dissociation of ench salt, second, the separation by the saturation of the

page_text: electrolytic bath with a solublo salt of the metal which it is desired to extract, and
third, the separation by the choice of an electrolyte which can only form a soluble
salt with the metal which it is desired to extract.
In witness whereof I the said William Robert Lake havo hereunto set my
hand and seal this nineteenth day of October in the year of our Lord One
thousand eight hundred and eighty two.
TWI