IMPROVEMENTS IN TREATING SOLUTIONS CONTAINING COPPER AND SILVER, OR EITHER OF THEM, TO OBTAIN METALLIC COPPER AND SILVER
Year: 1862

page_text: LETTERS PATENT to Gustav Bischof, junior, of Swansea, for the Invention
of "IMPROVEMENTS IN TREATING SOLUTIONS CONTAINING COPPER AND SILVER,
OR EITHER OF THEM, TO OBTAIN METALLIC COPPER AND SILVER."
Sealed the 10th October 1862, and dated the 26th April 1862.
PROVISIONAL SPECIFICATION left by the said Gustav Bischof at the
Office of the Commissioners of Patents, with his Petition, on the 26th
April 1862.
I, GUSTAV BISCHOF, junior, of Swansea, do hereby declare the nature of
the Invention for "IMPROVEMENTS IN TREATING SOLUTIONS CONTAINING COPPER
AND SILVER OR EITHER OF THEM, TO OBTAIN METALLIC COPPER AND SILVER," to be
as follows:-
This Invention has for its object improvements in treating solutions con-
taining copper and silver, or either of them, to obtain metallic copper and
silver. By treating copper and silver ores by well known processes, solutions
containing salts of copper and silver may readily be obtained. My Invention is
applicable to the treatment of such solutions, and also to the treatment of
other solutions containing salts of copper and silver, or either of them, and
consists in the use of the processes herein-after described, by means of which
the metals are obtained in the metallic state. For the purpose of obtaining
copper from solutions containing this metal, I in the first place obtain metallic
iron in a finely divided form by reducing the oxide or sulphuret or a salt of

page_text: iron, taking care to avoid fusion. The finely divided iron so obtained I introduce
in suitable proportion into the solution containing copper, and in this manner
I immediately obtain a precipitate of metallic copper very much purer than
the precipitated copper obtained by means of iron in other forms. When
solutions have to be treated, which, in addition to containing copper, also contain
persulphate of iron (Fe,O, + 3SO), if metallic iron is at once added, the
persulphate-is- decomposed and an insoluble basic sulphate produced, which
renders the precipitate very impure and causes a waste of metallic iron. To
prevent this and to obtain a purer precipitate of copper, I add, preliminary to
the process described, natural or artificial magnetic oxide of iron or carbonate
of iron; this decomposes the persulphate of iron without precipitating the
copper; the basic sulphate of iron thus produced is allowed to settle and is
separated, and after this the copper may be precipitated from the solution with
finely divided metallic iron, as above described. The metallic copper thus
precipitated may either be fused to obtain marketable copper, or employed for
the process of precipitating silver from its solutions. Metallic silver may also
conveniently be obtained from solutions containing it, by first precipitating
the silver as chloride, and then converting this into sulphuret, which may bo
readily done by treating it with a solution of sulphuret of sodium or potassium;
the sulphuret of silver obtained is easily reduced to a metallic form by heating
it in a current of air.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Gustav Bischof in the Great Seal Patent Office on the
23rd October 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GUSTAV
BISCHOF, junior, of Swansea, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of April, in the year of our Lord
One thousand eight hundred and sixty-two, in the twenty-fifth year of, Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,.
the said Gustav Bischof, Her special licence, that I, the said Gustav Bischof,
my executors, administrators, and assigns, or such others as I, the said
Gustav Bischof, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times there-
after during the term therein expressed, should and lawfully might make, g
use, exercise, and vend, within the United Kingdom of Great Britain and

page_text: Ireland, the Channel Islands, and Isle of Man, an Invention for "IMPROVE:
MENTS IN TREATING SOLUTIONS CONTAINING COPPER AND SILVER, OR EITHER OF THEM
TO OBTAIN METALLIC COPPER AND SILVER," upon the condition (amongst
others) that I, the said Gustav Bischof, my exécutors or administrators, by
an instrument in writing under my, or their, or one of their hands and
seals, should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, and cause the
same to be filed in the Great Seal Patent Office within six calendar months
next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Gustav Bischof, do hereby declare the
nature of the said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement thereof, that is to say :-
This Invention has for its object improvements in treating solutions con-
taining copper and silver, or either of them, to obtain metallic copper and
silver. By treating copper and silver ores by well known processes, solutions
containing salts of copper and silver may readily be obtained. My Invention is
applicable to the treatment of such solutions, and also to the treatment of other
solutions containing salts of copper and silver, or either of them, and consists
in the use of the processes herein-after described, by means of which the metals
are obtained in the metallic state.
. For the purpose of obtaining copper from solutions containing this metal,
I in the first place obtain metallic iron in a finely divided form by reducing
the oxide or sulphuret or a salt of iron, taking care to avoid fusion. The
finely divided iron so obtained I introduce in suitable proportion into the
solution containing copper, and in this manner I immediately obtain a
precipitate of metallic copper very much purer than the precipitated copper
obtained. by means of iron in other forms.
The following is the manner in which I prefer to proceed:-In order to obtain
the finely divided metallic iron, I prefer to take the burnt ores from the 'manu-
facture of sulphuric acid, more especially such as contain a small per-centage of
copper, as these ores very commonly do. This ore I grind to powder and mix
with pulverized coal (25 per cent. of coal is a suitable proportion); the mixture
is placed in retorts similar to those used in the manufacture of gas, and is.
licated for from 8 to 12 hours at a red heat, taking care to avoid fusion. In
order that the 'metal may not after the reduction become again oxidized by:
exposure to the air, there is placed in connection with the mouth of the retort,
and exterior of the furnace, a cylinder or chamber into which the ore when
properly reduced can be raked; the rake used for this purpose is, worked

page_text: through a small. hole. in.the cover of the retort. It is used to draw forward
the reduced ore into the mouth of the retort and to discharge it into the
cylinder or chamber below, in which it is allowed to cool. The cylinder or
chamber has a door which closes air-tight, but is opened to withdraw the
reduced ore when cool, in which state it will not oxidize readily. There is a
valve in the passage between the mouth of the retort and the cooling chamber,
which is opened in discharging the retort, but afterwards closed. To charge
the retort the cover is. removed, as is usual in gasworks, and the fresh charge
introduced. Should the ore have contained traces of metal, such as arsenic or
lead, they will be volatilized during the process of reduction, the latter will also
combine in part with the silica (of which a small per-centage is always present),
forming a silicate, which afterwards does not mix with the precipitated copper
when being fused. In employing the reduced ore or iron powder for the
process of precipitation, it is added to the solution containing copper in great
excess, stirring it with a wooden rake.. Thus the copper is precipitated from
the solution almost instantaneously, the chemical, action being such a strong.
one that the solutions are considerably heated. After the whole of the
copper has been precipitated the solution is allowed to run off and another.
quantity of solution added. In the same manner this is repeated until but a
small portion of the iron powder remains to be consumed by the precipitation
of copper. When the iron powder is about to be consumed (which is indicated
by the longer time required for the process of precipitation), I dissolve the
last traces of iron by adding the diluted wash waters from the process of
lixiviation of the copper from ores. Some substances, such as arsenic especially,
are only precipitated after the iron has been in contact with the solutions
containing copper and these substances for several hours. The precipitation
of the copper by my process being finished in a much shorter time, and the
solutions then being separated from the iron powder, the above substances
cannot be precipitated or mixed with the precipitated copper. Thus the
precipitated copper obtained is very much purer than the precipitated copper
obtained by means of iron, in other forms. Any copper there may have
been in the burnt iron ore will be reduced during the reducing process, and
will be found mixed with the precipitated copper. As there are very commonly
8 to 4 per cent. of copper in the burnt iron ore this copper will cover the
expense of the purchase of ore, as also the expenses of its reduction, in most
-cases leaving a surplus. When solutions have to be treated, which, in addition
to containing copper, also contain persulphate of iron (Fe,O, + 3SO,,), if
metallic iron is at once added, the persulphate is decomposed and an insoluble:
basic sulphate produced, which renders the precipitate very impure, and causes

page_text: a waste of metallic iron. To prevent this and to obtain a purer precipitate of
copper, preliminary to the process described, natural or artificial magnetic oxide
of iron or carbonate of iron may be added; this decomposes the persulphate of
iron without precipitating the copper. The basic sulphate of iron thus produced is
allowed to settle, and is separated, together with any excess of magnetic oxide or
carbonate of iron which may have been added, and after this the copper may
be precipitated from the solution with finely divided metallic iron, as above
described. The metallic copper precipitated by the finely divided iron, as
above described, may either be fused to obtain marketable copper or employed
for the process of precipitating silver from its solutions. Metallic silver may
also conveniently be obtained from solutions containing it by first precipitating
the silver as chloride, and then converting this into sulphuret, which may be
readily done by treating it with a solution of sulphuret of sodium or potassium,
a solution of the sulphuret being added in small excess to the precipitated
chloride of silver after this has been washed clean. The quantity of solution
of sulphuret required will be readily found from the specific gravity of the
solution and the weight of chloride of silver to be treated, the per-centage of
ulphuret in a solution being at once known from its specific gravity. The
sulphuret of silver obtained is easily reduced to a metallic form by heating it
in a current of air.
In witness whereof, I, the said Gustav Bischof, have hereunto set my
hand and seal this Eighteenth day of October, in the year of our
Lord One thousand eight hundred and sixty-two.
GUSTAV BISCHOF. (L.S.)