Iron Salts for Extracting Copper.
Year: 1888

page_text: Date of Application, 10th Feb., 1888
Specification Accepted, 16th Mar., 1888
Iron Salts for Extracting Copper.
I, JOSEF PERINO of Charlottenburg noar Berlin Prussia, Germany, Chemist do
hereby declare the nature of this invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement :-
My invention refers to a process for sulphating (converting into sulphates) in a
simple way the sulphurot of copper of copper pyrites before and after having boon
partially roasted in order to extract copper, and its novelty relates to the process of
sulphating sulphuret of copper by means of nitric iron salts.
The said salts owing to their great decomposibility give off oxygen at a moderate
heat in forming at the same time gaseous oxides of nitrogen and a residue of ferric
oxide.
The disposable oxygen combines first in its nascent state with the sulphuret of
copper and forms directly sulphate of copper, while the sulphates of iron of higher
degrees-which besides the sulphuret of copper are always present, are affected by
the oxygon with more difficulty. These oxidizing proportions of the sulphuret of
copper and the sulphuret of iron are depending upon the temperatures at which the
process is carried out. The reaction begins already at somewhat above 100° C. and
it increases gradually with the increase of the temperature which however must not
be superior to 200° C. The several sorts of tho existing copper-pyrites and the
copper pyrites containing iron-pyrites shew in this respect in their behaviour some
small differences, according to which the temperatures are to be regulated. The
duration of this oxidizing process may be 1 or 2 hours according to the increase of
heat.
According to circumstances it may be adviseable to increase, in producing simul-
taneously sulphate of iron, the heat up to the decomposing temperature of the sulphate
of iron (i.c. to low red-heat,) where the oxide of copper which may have been produced
in the first stage of the sulphating process, is also converted into sulphate, as sulphate
of copper is able to support higher temperatures than ferric sulphate.
The copper will thus be sulphated as perfectly as possible.

page_text: The obtained residue is then lixiviated with warm water and the copper of the
vitrol lye thus obtained precipitated according to any suitable method, preferably by
means of iron according to the well known cementing methods, and refined.
In practically carrying out the new method a regenerative process may very suitably
be connecte:l therewith, which process has principally for its object to produce nitric
iron salt. The lye of green vitriol resulting from the process is directly mixed with
a concentrated solution of nitrate of lime, whereby sulphate of lime (gypsum) as a
very difficultly soluble substance is eliminated and a solution of ferrous nitrate is
formed, which is run off and collected in receivers which are in communication with
the sulphating apparatus. The nitric oxides produced during the sulphating process
are conducted by a slowly passing air-current into the said receivers whereby a further
oxidation of ferrous salts to ferric salts will take place.
The nitric oxide thus obtained is oxydized again by the oxygen contained in the
added air and nitrous vapours are produced, which are absorbed in boiling heat by
carbonate of lime suspended in water (or also milk of lime). A gradual formation
of nitrato of lime now takes place, which will be more rapid in the presence of
arenaceous quartz.
The latter serves for obtaining ferrous nitrate from the lyo of green vitriol produced
by the cementing process.
Tho further converting of the ferrous nitrate into ferric nitrate is effected in tho
known way and the final employment of the latter in the sulphating procoss takes
place in the above described manner.
In precipitating the lyc of green vitriol by nitrate of lime the latter must not be
added in excess, as otherwise it would prejudice the sulphating process of tho
copper.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, 1 declare that what I
claim is :
: The disintegration of copper pyrites after they have been partially roasted or not'