IMPROVEMENTS IN THE EXTRACTION OF CERTAIN METALS FROM ORES, TOGETHER WITH THE PRODUCTION OF BYE PRODUCTS
Year: 1879

page_text: LETTERS PATENT to Juan Francisco Nepomuceno Macay, of Charapotó, in
the Republic of Ecuador, South America, and at present of York Street, Baker
Street, in the County of Middlesex, for the Invention of "IMPROVEMENTS IN
THE EXTRACTION OF CERTAIN METALS FROM ORES, TOGETHER WITH THE
PRODUCTION OF BYE PRODUCTS."
Sealed the 30th March 1880, and dated the 31st December 1879.
PROVISIONAL SPECIFICATION left by the said Juan Francisco Nepomuceno
Macay at the Office of the Commissioners of Patents on the 31st December
1879.
JUAN FRANCISCO NEPOMUCENO MACAY, of Charapotó, in the Republic of Ecuador,
South America, and at present of York Street, Baker Street, in the County of
Middlesex. "IMPROVEMENTS IN THE EXTRACTION OF CERTAIN METALS FROM
ORES, TOGETHER WITH THE PRODUCTION OF BYE PRODUCTS."
My Invention relates to an improved process for extracting, by the use of cupric
chloride (Cu Cl) and chloride of sodium in solution, the metals silver, lead, and
copper, from ores containing all or any of those metals in chemical combination
with sulphur (or, in the case of silver, with chlorine as well as well as sulphur, or
in the case of copper, with chlorine and oxygen (cupric oxychloride), whether these
sulphides (or chloride, or oxychloride), may be chemically combined or mechanically
mixed with other minerals in a simple or complex matrix.
When cupric chloride cannot be obtained to commence the process with, it may
be prepared thus:-Sulphate of copper and chloride of sodium, in solution, are
mixed together in the following proportions, viz. :—
Cupric sulphate crystallized
1 nart by weight.

page_text: chloride of sodium in sulphuric acid, whereby cupric chloride and sulphate of
sodium are formed. Also, by digesting black oxide of copper in hydrochloric acid,
whereby water and cupric chloride are formed.
The cupric chloride may be made by either of the above methods, or by any
other method, either in the presence of the ore to be treated or separately, but I
prefer to make it separately. I also make it in the presence of the ore when I
treat atacamite as hereafter described, or instead of atacamite I may use pure cupric
oxychloride, and treat it in the same way, according to the process for making
colcothar and cupric chloride, for which I have already applied for Letters Patent.
When lead ores are to be treated, and cupric chloride has been prepared by either
of the first two ways mentioned, the sulphate of sodium formed must be decom-
posed by adding a solution of chloride of calcium, whereby sulphate of calcium and
chloride of sodium are formed.
The sulphate of calcium being insoluble is separated by decantation or by filtering
off the liquid Thus a solution of cupric chloride and chloride of sodium can be
obtained free from any sulphate. In treating any other ores the sulphate of sodium
does not interfere with the process, although I still prefer to decompose it and
separate the sulphate of calcium which is produced.
Rain water should be used for the solutions of the salts of coppor and sodium,
and for washing the residues. Where rain water cannot be obtained water acidu-
lated with a little hydrochloric acid may be used, care being taken when treating
silver ore to remove all trace of acid from the residue before treating it with the
byposulphite of sodium solution.
The treatment by this Invention of the ores of the three metals above mentioned
can be effected in three different ways, and each of them comprehends some or all
of the following operations, viz.:-
(1.) Grinding, sifting, and dressing or concentrating the ore.
(2.) Mixing the ground ore with the solution of the salts (Cu Cl, + Na CI) in
an onamelled pot or other suitable vessel, and evaporating almost to dryness to
form a pulp.
(3.) Grinding the pulp resulting from the second operation in a stone mill, at the
same time heating it by means of steam.
"
"
(4.) Lixiviation or filtration of the soluble salts from the residue.
(5.) Separation of the salts of the metals from one another.
By stone mill, I mean a mill resembling the "arrastra or "Tahona of the
Mexicans, so constructed that no metallic part shall be exposed to the action of the
cupric chloride, and consisting of a circular base plate of granite or other hard stone
cemented together and oncircled by a watertight rim, stone mullers being made to
rotate upon the base plate.

page_text: ammonia) and afterwards with plain water to remove all free acid. After the residue
has been washed as stated above, and when entirely cold, I then proceed as in
Von Patera's process, that is, treating the residue with a cold dilute solution of
hyposulphite of sodium in order to entirely dissolve the chloride of silver which has
been left with the residue.
The stirrer should be kept in motion during the whole of the above operations.
After all the chloride of silver has been dissolved the hyposulphite solution is filtered
off, and the residue is repeatedly washed with cold water until all traces of the
hyposulphite of sodium (which holds the chloride of silver in solution) have been
extracted from the residue which contains sulphur and the gangue or matrix.
Procipitation of the Chloride of Silver from the Hyposulphite of Sodium
Solution. The chloride of silver held in solution by the hyposulphite solution is
transferred into an earthenware or iron pot glazed inside and boiled with pulverised
sulphur in the proportion of about 7 parts of sulphur to 1 part of silver, until all
the silver of the chloride of silver has been precipitated in the form of sulphido of
silver (Ag, S) leaving in solution the hyposulphite of sodium unchanged and ready
after being diluted to be used again. In order to know when all the chloride of
silver has been converted into sulphide of silver, I proceed as follows.-After the
hyposulphite solution has been boiling with the sulphur for about half an hour I
take out a small portion of the liquid and filter it, and then treat the clear filtrate
with a solution of sulphide of sodium. When the clear filtrate after being treated
as last described with sulphido of sodium shows only a slight turbidity in the
liquid, and not a black bulky precipitate, the operation of boiling is finished. Should
the liquid show a black bulky precipitate the boiling must be continued until the
desired reaction takes place. The byposulphite of sodium is then separated from
the sulphide of silver by filtration and the insoluble sulphide of silver washed.
The chloride of silver held in solution by the hyposulphite of sodium can also be
precipitated by any soluble sulphide, as for example sulphide of sodium, instead of
with sulphur, as already described, whereby sulphide of silver and chloride of
sodium are produced.
The hyposulphite of sodium is filtered off, and I proceed to wash the residue,
composed of sulphide of silver, as before stated. When the silver is precipitated
from the hyposulphite solution in this way by any soluble sulphide care must be
taken not to put an excess of this last reagent or to neutralize this excess, because
if an excess be present the hyposulphite of sodium solution will not be fit for use
again until it has been freed from any soluble sulphide, which can be readily done
by putting more chloride of silver into the solution to exhaust the excess of the
soluble sulphide.
As an alternative process, the residue from the leaching vat, instead of being
treated with a cold dilute solution of hyposulphite of sodium, as in Von Patera's
process hereinbefore described, may be treated, as in Zeiervogel's process, with
strong hot brine, in order to dissolve tho chloride of silver, from which solution the
silver, instead of being precipitated in the form of sulphide, as herein before
described, may be precipitated in the metallic state by metallic iron, whereby
ferrous chloride is at same time formed.
REDUCING THE SULPRIDE OF SILVER TO THE METALLIC STATE.
When sufficient sulphide of silver has been collected from various operations I
treat it again according to my Invention by the following process :-
I boil the sulphide of silver with cupric chloride and chloride of sodium, evaporate
it, and in some cases grind it in a stone mill; the chloride of silver which is pro-
duced by this reaction, after being freed of all copper salts, is next dissolved in a
hot saturated solution of chloride of sodium, which is separated from the sulphur

page_text: melted into ingots, and the ferrous chloride is kept for producing colcothar and
cupric chloride with oxychloride of copper, according to the Invention for which I
have obtained former Letters Patent.
TREATMENT OF THE LIQUID WHICH HAS BEEN SEPARATED BY FILTRATION FROM
THE RESIDUE IN THE LEACHING VAT.
The filtrate from the leaching vat and the two following brine washings are
collected together and boiled with metallic copper to decompose the chloride of
silver which is held in solution therein and precipitated in the metallic state. When
all the silver has heen precipitated the liquid is filtered off and treated as next
hereafter mentioned, and the precipitate is washed first with hot brine and after-
wards with very weak acidulated water, to free it from any copper salt, and this
precipitated cement silver is then melted into ingots as usual. The filtrate last
mentioned is treated as follows:-
The excess of metallic copper remaining after the silver is precipitated is removed
from the liquid, which is to be sufficiently diluted with the acidulated water
washings that have been used in the leaching vat to precipitate the cuprous chloride,
which comes down in the form of a white crystalline powder, leaving in solution
cupric chloride (when this salt has been used in excess) and chloride of sodium,
which are filtered off from the cuprous chloride, and are ready to be used again for
treating fresh ore. The other washings of the leaching vat, which contain very
dilute cupric chloride (when this salt has been used) in excess and chloride of
sodium, are concentrated by any ec.. omical means and used again for the
chlorination process.
As regards the cuprous chloride precipitate, I first expose it to the action of the
atmosphere in a very thin layer until it has been converted into a cupric oxychlorido
by the oxygen of the air. I employ the cupric oxychloride so obtained in the pro-
duction of colcothar, according to a process for which I have applied for other
Letters Patent, whereby the cupric oxychloride is at same time converted back into
cupric chloride for use again in the treatment of ores, as herein before described.
(b.) Chloride of Silver Ores.-Silver, which is found as a mineral in combination
with chlorine, is almost entirely insoluble in a hyposulphite solution or in brino,
but it is rendered directly soluble therein when the ore is treated according to the
process (a) above described for sulphide of silver, which process can therefore be
equally well employed for chloride of silver ores.
As applied to treating silver ores, the chief novelty of this process, considered as
a whole, consists in treating the raw ore direct without the use of mercury, which
is very expensive.

page_text: SEPARATION OF THE CUPROUS CHLORIDE FROM THE SULPHUR.
After the pulp has been transferred to the leaching vat, and the liquid has been
filtered off, the residue is repeatedly washed with hot brine, in order to dissolve the
cuprous chloride and filter it off from the residue. Then the brine which holds in
solution the cuprous chloride is diluted with water, whereby the cuprous chloride is
precipitated. The brine is then separated by filtration from the cuprous chloride, and
the cuprous chloride is converted into cupric oxychloride, as hereinbefore set forth.
The cupric oxychloride is then used in the preparation of colcothar, whereby it
is converted back into cupric chloride as hereafter described, for treating atacamite
by my other Invention above referred to. The cupric chloride thus produced and
the brine are then ready to be used again for treating fresh ore. The residue,
which is composed of the sulphur that has been set free and of the iron pyrites (if
any) that have been left undecomposed, is next burnt in the usual way to convert
the iron into ferrous sulphate, which I use in the process of my other Invention
to produce colcothar and convert cupric oxychloride into cupric chloride. To
obtain metallic copper a part of the cupric chloride which has been produced from
cupric oxychloride by my other process as above mentioned is precipitated in the
usual way by metallic iron, leaving of cource sufficient cupric chloride for treating
a fresh batch of the ore. The metallic copper which has been precipitated from
the cupric chloride is separated from the ferrous chloride and then melted into
ingots, refined, and toughened in the usual way. The ferrous chloride remaining I
also use in my other process above referred to for producing colcothar and converting
cupric oxychloride into cupric chloride.
To extract copper from atacamite the ore is first ground fine and then treated
according to the process of my other Invention, whereby the cupric oxychloride of
the mineral is converted into cupric chloride, and the ferrous salts used are
converted into ferric oxide or colcothar. I will now describe this process in full
as applied to the treatment of atacamito.
One method consists in boiling with excess of air in a solution of chloride
of sodium (Na Cl) a certain proportion of pulverised atacamite or cupric
oxychloride (Cu Cl, 3 Cu O 4 OH), together with ferrous or ferric sulphate
(Fe SO 7 Oн) or (Fе, 3 SO). The iron is oxidised at the expense of the
oxygen of the copper salt and of the air, and is precipitated in the form of ferric
oxide, leaving cupric chloride (Cu Cl₂) and sulphate of sodium (Na, SO) in solution.
In carrying out this process in practice I prefer to use ferrous sulphate, and I
proceed as follows:-Chloride of sodium in solution, ferrous sulphate, and
atacamite in the following proportions, viz. :-
Atacamite sufficient to contain 1 part by weight of pure cupric oxychloride.
Chloride of sodium 1-7 parts by weight.
Ferrous sulphate 07 parts by weight are boiled together in a wooden vat or
other suitable vessel, with free access of air until the ferric oxide is thrown down
as a pale yellowish red flocculent precipitate, which assumes a deeper red color by
continuing the boiling about a quarter of an hour longer.
The following is the chemical reaction:-2 Cu CL, 3 Cu O 4 OH, + 12 Na Cl +
6 Fe SO. 7 OH, +30 + 54 OH₁ = 8 Cu Cl₂ + 6 Na, SO, 10 OH + 3 Fe̟ O̟s +
44 OH,
After all the atacamite or insoluble cupric oxychloride has been converted into
cupric chloride (Cu Cl₂) and the iron precipitated as ferric oxide, the cupric chloride
is separated by filtration, and the residue of ferric oxide is well washed first with
water, and lastly with acidulated water, in order to free the ferric oxide and the
gangue from any salt of copper. The iron peroxide is then calcined in the usual
way to bring it to the desired color. When atacamite instead of pure cupric
oxychloride is treated, the colcothar produced will be of very inferior quality
on account of the gangue being mixed with it, but a comparatively pure portion of

page_text: evaporating dish or iron pot, glazed inside, with a strong solution of cupric chloride
and chloride of sodium in distilled water, and I boil the whole to evaporation. I
then treat the dry mass with cold or hot acidulated water, and boil it again until
all the soluble salts have been dissolved. I then filter off the liquid and wash the
residue repeatedly, first with hot acidulated water, and afterwards with hot brine,
until the residue is free from all cupric and cuprous chloride. Then the residue is
carefully examined to ascertain whether any insoluble copper compound is present
which was not before contained in the ore. If any such insoluble compound of
copper is found with the residue then in that case in treating the ore as hereafter
described the formation of such insoluble compound must be prevented by the
addition of free hydrochloric or sulphuric acid (the former only if lead is present)
to the solution of cupric chloride and chloride of sodium employed in the second of
the three operations hereafter referred to. The acid must be in excess in order to
neutralise the action of the chemical compound or element which reacts prejudicially
on the cupric chloride.
After making the above test and adding acid or not to the cupric chloride and
chloride of sodium solution, according to the result of the test, the fine pulverised
mineral is submitted to the first three operations, as in treating silver ores as
already described. The chemical reaction which takes place with the salts of the
metals, silver, copper, and lead contained in the complex ore is the same as when
the ore of the same metal is treated separately, that is to say, the sulphide of each
metal is decomposed by two atoms of chlorine derived from two molecules of the
cupric chloride (which is thereby reduced to cuprous chloride), and the sulphides
of the said metals, viz., Ag, Pb, Cu are converted into their respective chlorides and
subchlorides, viz., Ag Cl, Pb Cl,, Cu, Cl₂, the sulphur being set free. The iron pyrites,
sulphide of arsenic, and the gold, if they were present in the ore, are left undecom-
posed with the gangue, but the antimonious sulphide, if present, will have been
converted into antimonious chloride (Sb C) and the sulphur set free.
If antimony is present, after the pulp is transferred into the leaching vat, I first
let it cool down and filter off the liquid and keep separate the filtrate, which in
this case I may call filtrate A. Next I treat the residue in the same manner as
when lead ore has been treated by washing the residue repeatedly with hot water
to dissolve the chloride of lead formed. I collect all these washings together, and
I call them filtrate B I now treat the residue (in which the antimonious chloride
formed has been converted by the action of the water into antimonious oxychloride)
with hot saturated brine until all the chloride of silver and cuprous chloride
are dissolved; the liquid is then filtered off, and the operations of washing the
residue with hot saturated brine and filtering off the liquid are repeated until the
chloride of silver and cuprous chloride have been removed. I collect together all
these filtrates and call them filtrate C. The remaining residue containing the iron
pyrites, sulphide of arsenic, oxychloride of antimony, and the gold, with the rest
of the gangue, and perhaps a little silver chemically combined with it, is roasted
in the usual way in order to convert the iron pyrites into ferrous sulphate, which
after being formed is extracted from the mass by hot water, and may be used
according to my other Invention for producing colcothar and cupric chloride. The
gold is extracted from the gangue by any known process.
TREATMENT OF THE FILTRATES.
Filtrate A.-I add to this filtrate A (which contains cupric chloride, chloride of
sodium, and chloride of silver in solution) the filtrate b obtained from filtrate B, as
hereafter mentioned, and which contains cupric chloride, chloride of sodium, and
perhaps a little chloride of silver in solution, and I call it filtrate Ab
I treat filtrate Ab in the same manner as I have described hereinbefore in the
silver sulphide process, under the heading "Treatment of the Liquid which has
been Separated by Filtration from the Residue in the Leaching Vat."
Filtrate B.―This filtrate contains when cool cupric chloride, chloride of sodium,

page_text: and some chloride of silver in solution, and also cupreous chloride and chloride of
lead, which last two have been precipitated while the liquid has been cooling.
The liquid is filtered from the residue (and I call it filtrate b, and add it to filtrate
A, as above stated), and the residue is well washed with hot water in order to
separate the chloride of lead from the cuprous chloride. The chloride of lead in
solution is then boiled with metallic iron in order to precipitate it in the metallic
state, the ferrous chloride produced being utilised as already stated, and the cuprous
chloride is set apart for conversion into cupric oxychloride and subsequent use,
according to my other Invention.
Filtrate C. This filtrate contains strong brine, together with the cuprous
chloride and chloride of silver in solution (and perhaps a little cupric chloride),
which have been left with the residue after the removal of filtrates A and B. I
proceed to treat it in the following manner:-Metallic lead is put into the liquid,
whereby metallic silver and chloride of lead are formed, the liquid being at same
time boiled to dissolve the chloride of lead. The liquid is then filtered off from
the precipitated silver, and the excess of metallic lead used is removed. The
filtrate is then allowed to cool in order to precipitate the chloride of lead, from
which the brine is filtered off, and used again for dissolving more chloride of silver
in new operations.
The metallic silver is washed with weak acidulated water until it is free from:
any of the copper and lead salts, and is then melted into ingots. The chloride of
lead is treated according to the lead process herein before described.
When no antimonious compounds are present I proceed as follows:-After the
mechanical mixtures of the other minerals and the gangue have been separated by
washing or concentration, and it has been ascertained whether free acid is required
or not in the solution, I then proceed according to the first three operations of
treating silver ores The chemical reaction which takes place with the sulphides
of the metals Ag, Pb, Cu to be extracted is similar to that described in the case
when antimony is present, except that no antimony is present in this case. After
the pulp is transferred into the leaching vat I let it cool, and then filter off the
liquid, which I call filtrate A. Next I treat the residue as I treated the first
residue in the process for lead ores hereinbefore described, and the filtrates resulting
from this operation I collect together and call filtrate B. I now treat the residue
again (but in this case as I treated the first residue in the process for copper ores).
The washings containing the cuprous chloride I collect together and call filtrate C.
The residue which is left is again treated (but this time as I treated the second
residue in the silver ore process). I collect the washings resulting from this
operation and I call them filtrate D. The remaining residue (if it contains gold or
iron pyrites, or both together) I proceed to treat as I treated the last residue in the
first case of complex ore.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Juan Francisco Nepomuceno Macay in the Great Seal Patent Office
on the 30th June 1880.
JUAN FRANCISCO NEPOMUCENO MACAY, of Charapotó, in the Republic of Ecuador,
South America, and at present of York Street, Baker Street, in the County of
Middlesex. IMPROVEMENTS IN THE EXTRACTION OF CERTAIN METALS FROM
ORES, TOGETHER WITH THE PRODUCTION OF BYE PRODUCTS."
#
My Invention relates to an improved process for extracting by the use of cupric
chloride (Cu Cl) and chloride of sodium in solution the metals, silver, lead, and
copper from ores containing all or any of those metals, in chemical combination
with sulphur for in the case of silver with chlorine as well as sulphur, or in the case
of copper with chlorine and oxygen (cupric oxychloride) whether these sulphides
(or chloride or oxychloride) may be chemically combined or mechanically mixed
with other minerals in a simple or complex matrix.
may
When cupric chloride cannot be obtained to commence the process with, it may
be prepared by any of the well known methods as double decomposition between
sulphate of copper and chloride of sodium, or by digesting black oxide of copper
and chloride of sodium in sulphuric acid, or dissolving black oxide of copper in
hydrochloric acid. The cupric chloride may be made by cither of the above
methods, or by any other method, either in the presence of the ore to be treated or
separately, but I prefer to make it separately. I also make it in the presence of
the ore when I treat atacamite as hereafter described, or instead of atacamite I
use pure cupric oxychloride, and treat it in the same way according to the process
for making colcothar and cupric chloride, for which I have already obtained
Letters Patent, dated October 17th 1879, No. 4218. When lead ores are to be
treated and cupric chloride has been prepared by either of the first two ways
mentioned, the sulphate of sodium formed must be decomposed by adding a solution
of chloride of calcium, whereby sulphate of calcium and chloride of sodium are
formed. The sulphate of calcium being insoluble is separated by decantation or by
filtering off the liquid. Thus a solution of cupric chloride and chloride of sodium
can be obtained free from any sulphate. In treating any other ores the sulphate of
sodium does not interfere with the process, although I still prefer to decompose it
and separate the sulphate of calcium which is produced. Rain water should be
used for the solutions of the salts of copper and sodium and for washing the residues.
Where rain water cannot be obtained, water acidulated with a little hydrochloric
acid may be used, care being taken when treating silver ore to remove all trace of
acid from the residue before treating it with the hyposulphite of sodium solution.
The treatment by this Invention of the ores of the three metals above mentioned
can be effected by three methods, and each of them comprehends some or all of the
following operations, viz. :-(1), grinding, sifting, and dressing or concentrating the
re; (2), mixing the ground ore with the solution of the salts (Cu Cl, + Na Cl) in
in enamelled pot or other suitable vessel, and evaporating to dryness or almost to
Iryness; (3), grinding the mass resulting from the second operation in a stone mill,
t the same time heating it by means of steam; (4), lixivation or filtration of the
oluble salts from the gangue or residue; (5), separation of the salts of the metals
rom one another followed by their reduction to the metallic stato.
By stone mill I mean a mill resembling the "Arrastra" or "Tahona" of the
fexicans, so constructed that no metallic part shall be exposed to the action of the
upric chloride, and consisting of a circular base plate of granite or other hard
tone cemented together, and encircled by a watertight rim, stone mullers being
ade to rotate upon the base plate.

page_text: FIRST METHOD.
(1.) Grinding, Sifting, and Concentration of the Ore.-After the ore has been
crushed and concentrated if necessary, it must be ground to a fine powder in a
suitable mill and sifted through a sieve, having by preference 120 meshes to the .
linear inch. (Concentration of the ore is indispensable whenever the gangue or 5
matrix contains, or is composed of any chemical compound liable to decompose the
cupric chloride.)
(2) Mixing the Ground Ore with a Solution of Cupric Chloride and Chloride of
Sodium, and Evaporating to Dryness or almost to Dryness.-The ore after being
ground and sifted is placed together with a strong solution of cupric chloride and 1
chloride of sodium in an iron pot of the required size glazed inside, or in any other
suitable vessel (which should not present any metallic surface to the action of the
cupric chloride). The strong solution must cover the surface of the ore to such a
depth (say 6 inches), that there shall be chlorine in excess to chloridize all the
chloridizablecle ments or compounds. The mixture is then heated until the liquid 1
has been concentrated to a pulp or evaporated to dryness. The proportions are as
follows:-
Cupric chlorido
Chloride of sodium (Crystallised)
-
-
1 part by weight.
0.20 part by weight (more or less).
The use of chloride of sodium is not absolutely necessary, but it is very desirable, 2
because the brine dissolves the cuprous chloride formed, and prevents its oxidation
while the reaction takes place, and also because its presence seems to help and
hasten on in some peculiar way the chlorination of the metals which are intended
to be extracted.
(3.) Grinding the Pulp in a Stone Mill.-The contents of the pot in the form 2
of a very thick pulp or a dry mass is transferred to a stone mill, hereinbefore
described, and heated by live steam blown through it whilst the pulp or mass is
being ground. This operation is continued for a space of two hours more or less, after
which the pulp (the mass being now in the form of a pulp) is transferred into a
wooden leaching vat provided with a wooden stirrer where it is submitted to
operations Nos. 4 and 5, which operations vary according to the 4 different cases
that may occur, viz. -(1), extraction of silver from its ores; (2), extraction of
copper from its ores; (3), extraction of lead from its ores; (4), extraction of all
or any of the above metals from complex ores containing them combined with
sulphur, and also with chlorine in the case of silver, or with chlorine and oxygen in:
the case of copper (oxychloride of copper).

page_text: sodium in order to carry off the cuprous chloride which has been left with the
residue after the first filtration. Then the washing of the residue is continued with
hot acidulated water until it is free of all copper salt in solution (which may be
ascertained by testing the liquid with ammonia) and afterwards with plain water
to remove all free acid. After the residue has been washed as stated above, and
when entirely cold, I then proceed as in Von Patera's process, that is, treating the
residue with a cold dilute solution of hyposulphite of sodium in order to entirely
dissolve the chloride of silver which has been left with the residue.
The stirrer should be kept in motion during the whole of the above operations.
After all the chloride of silver has been dissolved, the hyposulphite solution is
filtered off and the residue is repeatedly washed with cold water until all traces
of the hyposulphite of sodium (which holds the chloride of silver in solution)
have been extracted from the residue which contains sulphur and the gangue
or matrix.
Precipitation of the Chloride of Silver from the Hyposulphite of Sodium
Solution The chloride of silver held in solution by the hyposulphite solution
is transferred into an earthenware or iron pot glazed inside, and boiled with
pulverized sulphur in the proportion of about 7 parts of sulphur to 1 part of silver,
until all the silver of the chloride of silver has been precipitated in the form of
sulphide of silver (Ag, S) leaving in solution the hyposulphite of sodium unchanged
and ready after being diluted to be used again. In order to know when all the
chloride of silver has been converted into sulphide of silver I proceed as follows:-
After the hyposulphite solution has been boiling with the sulphur for about half an
hour I take out a small portion of the liquid and filter it, and then treat the clear
filtrate with a solution of sulphide of sodium. When the clear filtrate, after being
treated as last described with sulphide of sodium, shows only a slight turbidity in
the liquid, and not a black bulky precipitate the operation of boiling is finished.
Should the liquid show a black bulky precipitate the boiling must be continued
until the desired reaction takes place. The hyposulphite of sodium is then separated
from the sulphide of silver by filtration, and the insoluble sulphide of silver washed.
The chloride of silver held in solution by the byposulphite of sodium can also be
precipitated by any soluble sulphide, as, for example, sulphide of sodium instead of
with sulphur as already described, whereby sulphide of silver and chloride of sodium
are produced. The byposulphite of sodium is filtered off, and I proceed to wash
the residue composed of sulphide of silver as before stated. When the silver is
precipitated from the hyposulphite solution in this way by any soluble sulphide
care must be taken not to put an excess of this last reagent (or to neutralize this
excess), because if an excess be present the byposulphite of sodium solution will not
be fit for use again until it has been freed from any soluble sulphide, which can bo
readily done by putting more chloride of silver into the solution to exhaust the
excess of the soluble sulphide.
As an alternative process the residue from the leaching vat instead of being
treated with a cold dilute solution of hyposulphite of sodium, as in the Von Patera's
process herein before described, may be treated as in Ziervogel's process with strong
hot brine in order to dissolve the chloride of silver, from which solution the silver
instead of being precipitated in the form of sulphide, as hereinbefore described,
may be at once precipitated in the metallic state by metallic iron, whereby ferrous
chloride is at same time formed, and the operation next described is dispensed
with.
Reducing the Sulphide of Silver to the Metallic State.-When sufficient sulphide
of silver has been collected from various operations I treat it again according to my
Invention by the following process:-1 boil the sulphide of silver with cupric
chloride and chloride of sodium, evaporate it, and in some cases grind it in a stone
mill. The chloride of silver which is produced by this reaction after being freed
of all copper salt is next dissolved in a hot saturated solution of chloride of sodium,
which is separated from the sulphur by filtration.
The sulphur is dried and pulverized to be used again, and the chloride of silver

page_text: in solution is precipitated by metallic iron, whereby metallic silver and ferrous
chloride are produced. The metallic silver (cement silver) so formed is melted into
ingots, and the ferrous chloride is kept for producing colcothar and cupric chloride
with oxychloride of copper, according to the Invention for which I have obtained
Letters Patent as aforesaid.
Treatment of the Liquid which has been Separated by Filtration from the
Residue in the Leaching Vat.-The filtrate from the leaching vat and the two
following brine washings are collected together and boiled with metallic copper
to decompose the chloride of silver (which is held in solution therein), and
precipitate it in the metallic state. When all the silver has been precipitated
the liquid is filtered off and treated as next hereafter mentioned, and the pre-
cipitate is washed first with hot brine and afterwards with very weak acidulated
water to free it from any copper salt, and this precipitated cement silver is then
melted into ingots as usual. The filtrate last mentioned is treated as follows:-
The excess of metallic copper remaining after the silver is precipitated is removed
from the liquid which is to be sufficiently diluted with the acidulated water
washings that have been used in the leaching vat to precipitate the cuprous
chloride which comes down in the form of a white crystalline powder, leaving
in solution cupric chloride (when this salt has been used in excess) and chloride
of sodium, which are filtered off from the cuprous chlorido and are ready to be
used again for treating fresh ore. The other washings of the leaching vat which
contain very dilute cupric chloride (when this salt has been used) in excess and
chloride of sodium are concentrated by any economical means, and used again for
the chlorination process.
As regards the cuprous chloride precipitate I first expose it to the action of the
atinosphere in a very thin layer until it has been converted into a cupric oxychloride
by the oxygen of the air. I employ the cupric oxychloride so obtained in the pro-
duction of colcothar, according to the process for which I have already obtained
Letters Patent as aforesaid, whereby the cupric oxychloride is at same time
converted back into cupric chloride for use again in the treatment of ores, as
hereinbefore described.
(b.) Chloride of Silver Ores.-Silver which is found as a mineral in combination
with chlorine is almost entirely insoluble in a hyposulphite solution or in brine,
but it is rendered directly soluble therein when the ore is treated according to the
process (a) above described for sulphide of silver, which process can therefore be
equally well employed for chloride of silver ores. As applied to treating silver
ores, the chief merit of this process considered as a whole consists in treating the
raw ore direct without the use of mercury, which is very expensive.

page_text: filter it off from the residue. Then the brine which holds in solution the cuprous
chloride is diluted with water, whereby the cuprous chloride is precipitated. The
brine is then separated by filtration from the cuprous chloride and the cuprous
chloride is converted into cupric oxychloride, as herein before set forth in describing
the silver ore process
The cupric oxychloride is then used in the preparation of
colcothar, whereby it is converted back into cupric chloride, as hereafter described
for treating atacamite by my other Invention above referred to. The cupric
chloride thus produced and the brine are then ready to be used again for treating
fresh ore.
To obtain metallic copper a part of the cupric chloride which has been
produced from cupric oxychloride by my other process, as above mentioned, is
precipitated in the usual way by metallic iron (leaving of course sufficient cupric
chloride for treating a fresh batch of the ore), and the metallic copper so precipitated
is separated from the ferrous chloride and then melted into ingots, refined, and
toughened in the usual way. The ferrous chloride remaining I also use in my
other process, above referred to, for producing colcothar and converting cupric
oxychloride into cupric chloride.
Treatment of Atacamite.-I digest or boil together in an open wooden vat or
other suitable vessel ferrous chloride (Fe Cl₂) in solution and atacamite or impure
cupric oxychloride in the following proportions, viz. :-
Atacamite, sufficient to contain 1 part by weight of pure cupric oxychloride.
Ferrous chloride
1 part by weight,
whereupon cupric chloride is formed and hydrated ferrous oxide produced, the
latter being then by the oxygen of the air converted into normal hydrated ferric
oxide, which by the action of heat is transformed into modified hydrated ferric
oxide, the chemical reaction being as follows:-
6 Fe Cl+2 Cu Cl₂ 3 Cu O 4 OH, + 30 = 3 Fе, O, OH₂ + 8 Cu Cl₂+ 5 OH,
After all the atacamite or insoluble cupric oxychloride has been converted into
cupric chloride (Cu Cl₂) and the iron into modified hydrated ferric oxide the cupric
chloride is separated by filtration, and the residue of modified hydrated ferric
oxide is well washed, first, with water and, lastly, with acidulated water, in order
to free the oxide and the gangue from any salt of copper. The modified hydrated
peroxide of iron is then calcined in the usual way to bring it to the desired colour.
Instead of taking the ferrous chloride already formed I may produce it in the
course of the process itself by the mutual reaction between a solution of chloride of
sodium (Na Cl) and ferrous or ferric sulphate (Fe SO, 70H.) or (Fe, 3 SO₁),
whereby ferrous chloride and sulphate of soda are formned, the subsequent reaction
of the ferrous chloride and the atacamite being the same as above mentioned. I
prefer to use ferrous sulphate, and the proportions are as follows:-
Atacamite, sufficient to contain 1 part by weight of pure cupric oxychloride,
Chloride of sodium, 1.7 parts by weight,
Ferrous sulphate, 0-7 part by weight.
These are boiled together as before and the following is the chemical reaction:-
2 Cu C₁₂ 3 Cu O 4 OH, + 12 Na Cl + 6 Fe SO, 7 ОH, +30 + 54 OH₂ =
8 Cu Cl, +6 Na, SO, 10 OH, + 3 Fe, O. OH, + 41 OH..
-

page_text: silver ore.
The chemical reactions are similar to those which take place in the
case of copper, and may be thus expressed :-
2 Cu Cl + Na Cl + Pb S = Cu, Cl, + NaCl + Pb Cl, + S.
-
After the pulp is transferred to the leaching vat from the mill I let it cool down
and then dilute it with common water, after which the liquid is filtered off from 5
the insoluble residue. I next wash this residue repeatedly with hot water to
remove all the chloride of lead, and this filtrate I collect apart from the first one.
When all the chloride of lead has been thus removed I let this filtrate which holds
it in solution cool down, whereby the chloride of lead is precipitated as a white
crystalline powder with some cuprous chlorido. The liquid is filtered off and this 1
third filtrate is put together with the first filtrate from the leaching vat. The
cuprous chloride and chloride of lead whith have remained as residue are then
boiled with common water, whereby the chloride of lead is dissolved and is then
separated from the cuprous chloride by filtration. To produce metallic lead the
chloride of lead solution is boiled with metallic iron, whereby metallic lead is 1
precipitated and ferrous chloride is formed. The ferrous chloride is filtered off from
the metallic lead and is used in the process of my other Invention above referred
to, and the metallic lead is melted into ingots.
The residue in the leaching vat is treated in order to separate from the gangue
the small amount of cuprous and cupric chloride which has been left with the 2
residue, in the same way as in the case of the copper ores, and this fourth filtrate is
put together with the first and third filtrates. The cupric chloride and chloride
of sodium in solution in these filtrates are filtered off leaving the cuprous chloride
which has been precipitated by diluting the solution. The two former can be used
in treating a fresh batch of ore, and the latter is used in the process of my other 1
Invention above referred to.
The various processes herein before described for simple ores are all included
under the first method hereinbefore referred to, which is distinguished from the
second and third methods hereinafter referred to by the mixture of the mineral
with cupric chloride and chloride of sodium being evaporated at a separate
operation to a pulp or dry mass. The first method generally produces the best
results when the ore is very rich, and the matrix which carries the mineral is
composed of quartz or any other hard substanco, but when the ore is less rich it
will be a question of economy whether this or the next method should be adopted
to be decided according to circumstances.
SECOND METHOD.
This method consists in not evaporating as a separate operation. In carrying it
out I proceed as follows:-
=
After the ore (which may be any one of those whose treatment has been
described under the first method) has been reduced to powder it is directly
transferred to the stone mill where cupric chloride and chloride of sodium are added
to it in the same proportions as before stated in the second operation of the first
method, and the pulp is heated by means of steam passing through an iron worm
enamelled or glazed outside, which worm runs round inside the mill near the sides,
its upper end being by preference connected with a superheater, and its lower end
passing outside of the mill to drain off the condensed water. The pulp is thus
heated and ground for about 5 or 6 hours until it has become very thick or has
been evaporated to dryness. The washing of the residue and the separation of
the metal or metals are conducted in the way already mentioned for the ore
of that metal, or in the way hereafter described for the complex ores as the case
may ha
3

page_text: methods, I prefer to reduce the ore by a "Carr's disintegrator," or any other
machine of the kind, to the condition of coarse sand, and after concentrating it if
necessary, put it direct into the stone mill where the mechanical and chemical
treatment of the ore is carried on in the same way as in the second method last
described, with the only difference that the operation of grinding in the stone mill
must be continued until the ore has been reduced to a very fine powder. The
washing of the residue and the separation of the metal or metals from the solution
is carried on in the way already described under the first method for the ore of
that metal as hereafter described, for the complex ores as the case may be.
COMPLEX ORES.
The processes herein described are applicable to the separation and extraction of
two or all three of the metals, silver, lead, and copper, carried in the state of
sulphides (whether mechanically mixed or chemically combined with one another)
in a simple or a complex matrix or gangue (or the silver in the state of chloride, or
chloride and native silver, or the copper in the state of oxychloride or oxychloride
and native copper), whether these sulphides (or chloride and native silver or
oxychloride of copper and native copper) are mechanically mixed with other
minerals of a varied chemical composition or free from foreign admixtures, or
whether these three sulphides are in chemical combination or mechanical mixture
with the sulphide of antimony, arsenic, iron, and gold, or either of them or with
the sulphides of the other rare metals, or with any other sulphide which will not
precipitate the copper salt from an acidulated solution of cupric chloride in any
other form than cuprous chloride. In treating this ore in practice I proceed as
follows: The ore after being ground is or may be submitted to the mechanical
operation of dressing or concentration in order to separate as far as possible the
mechanical mixtures of the other minerals present in the ore as well as the gangue
or matrix from the mineral or minerals containing the silver, lead, and copper,
which after being thus separated and before going any further must be submitted
to the following preliminary test :—
I take a small portion of the mineral to be treated, and I put it into a small
evaporating dish or iron pot, glazed inside with a strong solution of cupric chloride
and chloride of sodium in distilled water, and I boil the whole to dryness. I then
treat the dry mass with cold or hot acidulated water, and boil it again until all the
soluble salts have been dissolved. I then filter off the liquid, and wash the residue
repeatedly first with hot water and afterwards with hot brine until the residue is
free from all cupric and cuprous chloride; then the residue is carefully examined to
ascertain whether any insoluble copper compound is present which was not before
contained in the ore. If any such insoluble compound of copper is found with the
residue, then in that case in treating the ore as hereafter described the formation of
such insoluble compound must be prevented by the addition of free hydrochloric or
sulphuric acid (the former only if lead is present) to the solution of cupric chloride
and chloride of sodium employed in the second of the three operations hereafter
referred to. The acid must be in excess, that is to say, two molecules of acid to one
molecule of the chemical compound or element which reacts prejudicially on the
cupric chloride. After making the above test, and adding acid or not to the cupric
chloride and chloride of sodium solution, according to the result of the test, the fine
pulverized mineral is submitted to the first three operations, as in treating silver
ores as already described. The chemical reaction which takes place with the salts
of the metals, silver, copper, and lead contained in the complex ore is the same as
when the ore of the same metal is treated soparately, that is to say, the sulphide of
each metal is decomposed by two atoms of chlorine derived from two molecules of the
cupric chloride (which is thereby reduced to cuprous chloride) and the sulphides of
the said metals, viz., Ag, Pb, Cu, are converted into the respective chlorides and
subchloride of the said metals, viz., Ag Cl, Pb CL., Cu, Cl₂, the sulphur being set free.
The sulphide of arsenic and the gold, and the excess (if any) of the iron pyrites, if

page_text: they were present in the ore, are left undecomposed with the gangue, but the
antimonious sulphide, if present, will have been converted into antimonious chloride
(Sb Cl), and the sulphur set free. If antimony is present after the pulp is trans-
ferred into the leaching vat I first let it cool down. I dilute, if necessary, and
filter off the liquid, and keep separate the filtrate, which in this case I may call
filtrate A. Next I treat the residue in the same manner as when lead ore has been
treated by washing the residue repeatedly with hot water to dissolve the chloride
of lead formed. I collect all these washings together, and I call them filtrate B. I
now treat the residue (in which the antimonious chloride formed has been converted
by the action of the water into antimonious oxychloride) with hot saturated
brine until all the chloride of silver and cuprous chloride are dissolved. The liquid
is then filtered off, and the operations of washing the residue with hot saturated
brine and filtering off the liquid are repeated until the chloride of silver and cuprous
chloride have been removed. I collect together all these filtrates and call them
filtrate C. The remaining residue containing the sulphide of arsenic, oxychloride
of antimony, and the gold, together with the excess (if any) of the iron pyrites and
the rest of the gangue, and perhaps a little silver chemically combined with it, is
roasted in the usual way in order to convert the iron pyrites into ferrous sulphate,
which after being formed is extracted from the mass by hot water, and may be
used according to my other Invention for producing colcothar and cupric chloride
The gold is extracted from the gangue by any known process
Treatment of the Filtrates.-Filtrate A. I add to this filtrate A (which contains
cupric chloride, chloride of sodium, and chloride of silver in solution) the filtrate b
obtained from filtrate B, as hereafter mentioned, and which contains cupric chloride,
chloride of sodium, and perhaps a little chloride of silver in solution, and I call it
filtrate A, b. I treat filtrate A, b, in the same manner as I have described herein-
before in the silver sulphide process under the heading "Treatment of the Liquid
which has been Separated by Filtration from the Residue in the Leaching Vat."
Filtrate B. This filtrate contains when cool cupric chloride, chloride of sodium,
and some chloride of silver in solution, and also cuprous chloride and chloride of
lead, which last two have been precipitated while the liquid has been cooling. The
liquid is filtered from the residue (and I call it filtrate b, and add it to filtrate A, as
above stated), and the residue is well washed with hot water in order to separate
the chloride of lead from the cuprous chloride. The cloride of lead in solution is
then boiled with metallic iron in order to precipitate it in the metallic state, the
ferrous chloride produced being utilised as already stated, and the cuprous chloride
is set apart for conversion into cupric oxychloride and subsequent use, according to
my other Invention.
Filtrate C. This filtrate contains strong brine together with the cuprous chloride
and chloride of silver in solution (and perhaps a little cupric chloride) which have
been left with the residue after the removal of filtrates A and B. I proceed to
treat it in the following manner :-Metallic lead is put into the liquid whereby
metallic silver and chloride of lead are formed, the liquid being at same time boiled
to dissolve the chloride of lead; the liquid is then filtered off from the precipitated
silver and the excess of metallic lead used is removed. The filtrate is then allowed
to cool in order to precipitate the chloride of lead from which the brine is filtered
off and used again for dissolving more chloride of silver in new operations. The
metallic silver is washed with weak acidulated water until it is free from any of
the copper
and lead salts, and is then melted into ingots. The chloride of lead is
treated according to the lead process here.nbefore described.
When no antimonious compounds are present I proceed as follows:-After the
mechanical mixtures of the other minerals and the gangue have been separated by
washing or concentration, and it has been ascertained whether free acid is required
or not in the solution, I then proceed according to the first three operations of treating
silver ores.
The chemical reaction which takes place with the sulphides of the
metals Ag, Pb, Cu, to be extracted is similar (except that antimony is absent) to
that described in the case when antimony is present. After the pulp is transferred

page_text: into the leaching vat I let it cool and then filter off the liquid which I call filtrate
A'. Next I treat the residue as I treated the first residue in the process for lead
ores hereinbefore described, and the filtrates resulting from this operation I collect
together and call filtrate B¹. I now treat the residue again (but in this case as I
treated the first residue in the process for copper ores); the washings containing
the cuprous chloride I collect together and call filtrate C'. The residue which is
left is again treated (but this time as I treated the second residue in the silver ore
process); I collect the washings resulting from this operation and I call them
bltrate D. The remaining residue (if it contains gold or iron pyrites, or both
together) I proceed to treat as I treated the last residue in the first case of
complex ore.
Treatment of these Filtrates.-Filtrate A¹. I put together filtrate A¹, filtrate b¹
(obtained from filtrate B'), and filtrate C³, and I call them filtrate A'¿¹ C¹.
Filtrate A¹¹ C¹ contains chloride of sodium, cupric and cuprous chlorides, and
chloride of silver, and I treat it in the same manner as I have treated the first
filtrate in the silver ore process hereinbefore described.
Filtrate B¹. This filtrate is similar to filtrate B in the first case and I treat it in
the same way.
Filtrate D. This filtrate contains in solution in the byposulphite of sodium the
chloride of silver, and perhaps very little copper salt which have been left in the
residue after the removal of filtrates A¹ B¹ C³, and I treat it in the same manner as
the last filtrate of the silver sulphide process.
From the foregoing it will be obvious that complex ores may be treated by the
second and third methods as well as by the first.
Having described the nature of my Invention and the manner of performing the
same, I declare that what I claim as my Invention to be protected by the herein-
before in part recited Letters Patent is,―
1st. The extraction of silver from ores in which it exists in the form of a sulphide
or an insoluble chloride (with or without native silver) combined or not with the
sulphides of the other elements, or mixed with other chemical compounds by the
combined process herein before described, consisting in the treatment of the ore
with cupric chloride in solution (with or without chloride of sodium) and dissolving
the chloride of silver thus formed in brine or in a solution of hyposulphite of
sodium, substantially as herein before described, the chloride of silver being
reduced to the metallic state by any suitable process.
2nd. The extraction of copper from ores in which it exists in the form of
sulphides (with or without native copper) combined or not with the sulphides of
the other elements, or mixed with other chemical compounds, and the production of
modified hydrated ferric oxide and cupric chloride by the combined process, con-
sisting (1) in the reaction of cupric chloride (with or without chloride of sodium)
in solution on the sulphide of copper of the ore, and (2) in the reaction of cuplic
oxychloride (obtained by oxidising the cuprous chloride thus formed) with a solution
of ferrous chloride, whereby cupric chloride and modified hydrated peroxide of iron
are formed, the precipitation of part of the cupric chloride in the metallic state by
metallic iron leaving ferrous chloride in solution for subsequent use, and the remainder
of the cupric chloride solution for treating a fresh batch of ore, substantially as
described herein and in the Specification of my other Patent above referred to.
3rd. The direct treatment of the mineral "atacamite" by ferrous chloride
(whether the ferrous chloride be taken ready made or be produced in the course of
the process) whereby, by mutual reaction, cupric chloride and hydrated ferrous
oxide are produced, the hydrated ferrous oxide being then spontaneously converted
into normal hydrated ferric oxide which, by the action of heat, is transformed into
modified hydrated ferric oxide, substantially as herein described, the cupric chloride
being afterwards reduced to the metallic state.
4th. The extraction of lead from ores in which it exists in the form of sulphide
by the reaction of cupric chloride in solution (with or without chloride of sodium)
on the sulphide of lead, whereby cuprous chloride and chloride of lead are produced

page_text: and the sulphur is set free, substantially as described in the lead process herein
specified, the chloride of lead being then reduced to the metallic state by any
known process, but preferably by the process described, whereby ferrous chloride
is produced for use in my other process as described.
5th. The chlorination at one operation of silver, copper, and lead in a complex
ore or mineral such as herein specified in which any two or more of these metals
exist in the form of sulphides (or of chloride in the case of silver, or of oxychloride
in the case of copper) with or without native silver or copper by the reaction of
cupric chloride in solution (with or without chloride of sodium) on the sulphides of
these metals and the successive separation of the chlorides of these metals, 1
substantially as described in the complex ores process herein set forth, the several
chlorides being precipitated and reduced to the metallic state by any known
process, but preferably by the process described.
In witness whereof, I, the said Juan Francisco Nepomuceno Macay, have
hereunto set my hand and seal, this Twenty-ninth day of June, in the 1
year of our Lord One thousand eight hundred and eighty.