IMPROVEMENTS IN THE PROCESS OF TREATING COPPER PYRITES FOR THE EXTRACTION OF THE METALS CONTAINED THEREIN AND IN THE APPARATUS USED THEREFOR WHICH ARE ALSO 33 APPLICABLE TO OTHER KINDS OF COPPER ORES
Year: 1883

page_text: PROVISIONAL SPECIFICATION left by Sydney Pitt at the Office of the
Commissioners of Patents on the 2nd June 1883. Communicated to him
from abroad by Andrew Rutherford Gray of the City of Edinburgh Scotland
now temporarily resident in the City of Montreal Province of Quebec Canada
SYDNEY PITT of Sutton in the County of Surrey "IMPROVEMENTS IN THE
PROCESS OF TREATING COPPER PYRITES FOR THE EXTRACTION
OF THE METALS
CONTAINED THEREIN AND IN THE APPARATUS USED THEREFOR WHICH ARE ALSO
33
APPLICABLE TO OTHER KINDS OF COPPER ORES [communicated to him from
abroad by Andrew Rutherford Gray of the City of Edinburgh Scotland now
temporarily resident in the City of Montreal Province of Quebec Canada]
The Invention has for its object to provide means for the complete condensation
of the gases escaping during the treatment of copper pyrites by the usual acid
solvents so that but an infinitesimal proportion of such solvents is lost, thus
allowing of the employment of nitric acid, which from its costliness has hitherto
been confined for such purposes to the laboratory.
The invention may be described as consisting in drawing off by means of a pump
or pumps the sulphurous gas and nitric oxides evolved during the different stages
of the treatment of the pyrites (these gases being usually passed through a sulphuric
acid chamber) and forcing them through a series of condensing vats, thus enabling
a determined quantity of gas to be re-used repeatedly at very little cost.
From this
The ore is first treated in pyrites burners of any ordinary type, a pipe conveying
the gas to a common sulphuric acid chamber suitably constructed.
chamber a pipe at any point or points of which are placed a pump or pumps runs
to the first of a series of condensing vats connected together by pipes, a pipe
communicating from the last vat with the main return pipe receiving the gases
from the leaching tanks. Pipes lead from these several leaching tanks to the
return pipe.
The silver contained in the ore is precipitated in settles, pipes, taking the gases
from each into another return pipe which conveys them to the pipe connecting the
pyrites burners with the sulphuric acid chamber. The copper is precipitated in
tanks in the presence of scrap or spongy iron which is therein rendered soluble.
The iron solution is treated in the evaporator and the iron sulphates from the
evaporator converted into oxides of iron in a furnace, both these communicating
with the pipe leading to sulphuric acid chamber. The copper solution from the

page_text: leaching tanks may if desired be received in settles also connected by suitable pipes
with the main return pipe.
I will now describe the operation of my invention when treating pyrites ores
such as are found at certain points in the Province of Quebec, Canada.
I first burn the ore in the pyrites burners, the sulphurous gas and nitric oxides
being drawn by means of the pump or pumps along the pipe from the burners
through the sulphuric acid chamber whence these are taken to the condensing vats
any uncondensed gas passing from the last of these to the main return pipe.
I prefer that the one of these vats into which the gases first enter and in which
most of the condensation will be done should be filled with water, the others being
charged with a solution of proto-sulphate of iron, which by the action of the nitric
oxides passing through it is converted into per-sulphate of iron.
This per-sulphate of iron is taken to the leaching tanks in which it assists in
rendering the copper soluble.
The ore, after having been treated in the pyrites burners and pulverized, being,
if desired, previously submitted to the action of a common calcining furnace, is
then conveyed to the leaching tanks and the acid from the condensing vats, (with,
if desired, any proportion of fresh acid) run in upon it, the action being immediate
and the copper thereby rendered soluble. The nitric oxides arising from this
operation are conveyed from the several leaching tanks through their connecting
pipes to the main return pipe. The copper in solution is then, should the liquor
be muddy, first taken to one set of settles, but if, as is generally the case, it comes
off clear, the solution is taken to, the other settles in which the silver contained in
the solution is extracted in the best known way. As soon as the silver is
precipitated the copper solution is removed to the tanks in which the copper is
precipitated in the presence of spongy or scrap iron. When scrap iron is expensive
I prefer to crystallize the copper and iron from the solution let into the tanks and
take the crystals to the calcining furnace, where the sulphuric acid and nitric
oxides are sent off to sulphuric acid chamber the weak liquors being sent back to
the leaching tanks and the copper smelted or rendered soluble.
The vessels above mentioned are all suitably connected with the subsidiary pipe
led to the pipe from pyrites burners to sulphuric acid chamber.
The copper obtained by precipitation in the tanks can be removed after the iron
solution is drawn off and treated for transport and use. The iron solution is taken
to the evaporator and the sulphates of iron there obtained treated in the furnace
so as to produce oxide of iron. The sulphurous acid and sulphur evolved during
these two processes are conveyed to the sulphuric acid chamber.
It will be seen that as by the arrangement of the several parts operating as
just described the nitric oxide and sulphurous gas evolved during the several
processes are recovered by condensation hardly any waste can take place and a
given determined quantity of nitric acid can be used over and over again, thus
rendering its employment a commercial possibility.
Besides this the repeated passage of the nitric oxide through the sulphuric acid
chamber will be the means of making sulphuric acid more cheaply than by the
present method and the acid thus condensed can be used to render oxides,
carbonates and sulphides of copper soluble.
An incidental result of my invention is the production in the condensing vats
of per-sulphate of iron to be used in the leaching tanks.
Should the sulphuric acid chamber be omitted the pipes to and from it will be
connected and a length of pipe afford communication between these and the main
return pipe.