Improvements relating to the Treatment of Complex Sulphide Ores.
Year: 1893

page_text: Date of Application, 16th May, 1893-Accented, 5th Aug., 1893
COMPLETE SPECIFICATION.
Improvements relating to the Treatment of Complex
Sulphide Ores.
We, WALTER RENTON INGALLS, Mining Engineer and Metallurgist, of 27 Park
Place, New York City, New York, and FRANCIS WYATT, Chemist, of 24 Park
Place, New York City, New York, both in the United States of America, do
hereby declare the nature of our invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the following
statement:—
Our invention relates to processes for the treatment of complex sulphide ores, and
more especially to what are termed low grade argentiferous ores of this class, which
contain zinc, lead and iron in the form of sulphides.
The object of our invention is to provide a process, by which such low grade ores
can be effectively and economically treated, and all three of the valuable metals,
which they contain, can be recovered at such cost, as to be capable of sale at a
profit. We accomplish this result by treating the ores in such way that whatever
expensive chemical reagents are employed in the recovery of the zinc, lead and
silver are in their turn recovered, so that substantially the same quantity of said
reagents is used over and over again with comparatively trivial loss, and thus the
cost of said reagents is limited to the amount originally required to start the process
and continue it until said reagents are recovered sufficiently to replace the amount
used in the initial stages of the process.
The operation of our improved process is as follows: The complex sulphide ore
previously reduced to a proper size, as usual in smelting, is first roasted in a suitable
furnace, for the purpose of sulphatizing the zinc. The sulphurous acid driven out
by this process is collected in a lead chamber, where it is converted into sulphuric
acid in the usual manner. This sulphuric acid with water is then applied to the
roasted ore to lixiviate it. By this treatment the zinc sulphate is dissolved, and
the other ingredients including the lead, iron and silver form a residue which is
handed over to the lead smelter to be treated by any of the known processes of
smelting simple lead ore.
If any iron by reason of its solubility entered the zinc sulphate solution, it is to
be precipitated therefrom by the addition of a small quantity of zinc oxide obtained
at a later stage of the process and the zinc thus freed from the iron is then
precipitated in the form of zinc carbonate or a mixture of carbonate and hydroxide
by the addition of carbonate of soda which was originally obtained from an outside
source for the treatment of the first charge of ore, but which was recovered at a
subsequent stage of the process for the treatment of all further charges. The zinc
carbonate is washed, dried, and calcined until it is reduced to zinc oxide, a small
quantity of which is used as before stated to precipitate the iron from the zinc
sulphate solution, but the main body of which is converted into spelter in the usual
way or marketed as oxide.
When the zinc is withdrawn from the sulphate solution, there remains a solution
of sodium sulphate. This solution is evaporated to dryness and the sodium sulphate
thus obtained is mixed with coal and with a small quantity of common salt or
sodium chloride and then heated to form carbon monoxide and impure sodium
sulphide.
The carbon monoxide is burnt to convert it into carbonic acid gas, which is
carried to a tower or other suitable device to be hereafter referred to.
The impure
sodium sulphide is leached and the solution decanted to free it from its impurities;
and the sodium sulphide solution is then carried to the before mentioned tower there
to be treated with carbonic acid gas to convert it into bi-carbonate of soda. The

page_text: carbonic acid gas required for this purpose is obtained partly from the burning of
the carbon monoxide before described, but chiefly by burning limestone in a separate
kiln. The calcium oxide or lime resulting from this burning. is a marketable
product. An additional amount of carbonic acid gas comes back to said tower
recovered at a subsequent stage of the process.
While the bi-carbonate of soda is thus obtained, the sulphur contained in the
sodium sulphide is given off as sulphuretted hydrogen, which upon being burned,
produces sulphurous acid, which is carried to the lead chamber mentioned at the
beginning of the process, where it unites with the sulphurous acid obtained from
roasting the ore. As in this way all the sulphur originally in the ore has been
recovered, there may be an excess of sulphuric acid over that required for treating
the ore, in which case the excess may be sold.
The bi-carbonate of soda is heated in a suitable furnace giving off carbonic acid,
which is fed to the tower aforesaid. The sodium carbonate thus obtained replaces
the sodium carbonate originally employed in precipitating the zine from the zinc
sulphate solution. It will thus be seen that this process is not only absolutely
continuous, but that it is conducted without waste and that the by-products obtained,
namely, lime and sulphuric acid, are of saleable value.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:
1. The process of treating complex sulphide ores, which consists, first, in subjecting
the ore to a sulphatizing roasting and recovering the driven off sulphur in the form
of sulphuric acid; second, lixiviating the roasted ore with said sulphuric acid and
water and removing the iron from the solution, if necessary; third, precipitating the
zine from said solution in the form of carbonate or carbonate and hydroxide, by the
use of sodium carbonate, and subsequently converting the same into zinc oxide;
fourth, evaporating the sodium sulphate obtained from the zinc sulphate solution
and heating the same with sodium chloride and coal, to convert it into sodium
sulphide; fifth, converting the sodium sulphide into bi-carbonate of soda by
dissolving the same in water and treating the solution with carbonic acid gas and
recovering the sulphur in the form of sulphuric acid, as described; and lastly, con-
verting the bi-carbonate of soda into sodium carbonate, by heating the same, to
drive off the water and carbonic acid gas, substantially as described and for the
purpose specified.
2. The process of treating complex sulphide ores, which consists, first, in subjecting
the ore to a sulphatizing roasting and recovering the driven off sulphur in the form
of sulphuric acid; second, lixiviating the roasted ore with said sulphuric acid and
water and removing the iron therefrom, if necessary; third, precipitating the zinc
from said solution in the form of carbonate or carbonate and hydroxide, by the use
of sodium carbonate, and subsequently converting the same into zinc oxide; fourth,
evaporating the sodium sulphate obtained from the zinc sulphate solution and
heating the same with sodium chloride and coal, to convert it into sodium sulphide;
fifth, converting the sodium sulphide into bi-carbonate of soda, by dissolving the
same in water and treating the solution with carbonic acid gas; and lastly, con-
verting the bi-carbonate of soda into sodium carbonate by heating the same, to
drive off the water and carbonic acid gas, substantially as described and for the
purposes specified.
3. The process of treating complex sulphide ores, which consists, first, in subjecting
the ore to a sulphatizing roasting; second, lixiviating the roasted ore with water
and sulphuric acid and removing the iron therefrom, if necessary; third, precipitating
the zinc from said solution in the form of carbonate or carbonate and hydroxide, by
the use of sodium carbonate, and subsequently converting the same into zinc oxide;
fourth, evaporating the sodium sulphate obtained from the zinc sulphate solution,
and heating the same with sodium chloride and coal, to convert it into sodium
sulphide; fifth, converting the sodium sulphide into bi-carbonate of soda by

page_text: dissolving the same in water and treating the solution with carbonic acid gas and
recovering the sulphur in the form of sulphuric acid, as described; and lastly,
converting the bi-carbonate of soda into sodium carbonate, by heating the same, to
drive off the water and carbonic acid gas, substantially as described and for the
purpose specified.
4. The process of treating complex sulphide ores, which consists, first, in subjecting
the ore to a sulphatizing roasting; second, lixiviating the roasted ore with water
and sulphuric acid and removing the iron therefrom, if necessary; third, pre-
cipitating the zine from said solution in the form of carbonate or carbonate and
hydroxide, by the use of sodium carbonate, and subsequently converting the same
into zinc oxide; fourth, evaporating the sodium sulphate obtained from the zinc
sulphate solution, and heating the same with sodium chloride and coal, to convert it
into sodium sulphide; fifth, converting the sodium sulphide into bi-carbonate of
soda, by dissolving the same in water and treating the solution with carbonic acid
gas; and lastly, converting the bi-carbonate of soda into sodium carbonate, by
heating the same, to drive off the water and carbonic acid gas, substantially as
described and for the purposes specified.
Dated this 24th dor of Anil 1002
WALTER RENTON INGALLS.
FRANCIS WYATT.
Haseltine, Lake & Co.,
45, Southampton Buildings, London, Agents for the Applicants.