Improvements in the Treatment of Sulphide Ores of Lead Preparatory to Smelting the same, and Incidentally in Obtaining Sulphurous Acid..
Year: 1896

page_text: Date of Application, 16th Apr., 1896.
Complete Specification Left, 16th Feb., 1897-Accepted, 15th Apr., 1897
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Sulphide Ores of Lead
Preparatory to Smelting the same, and Incidentally in
Obtaining Sulphurous Acid..
We, THOMAS HUNTINGTON and FERDINAND HEBERLEIN, both of Pertusola, near
Spezzia, in the .Kingdom of Italy, Metallurgical Engineers, do hereby declare the
nature of this invention to be as follows:-
This invention relates to the treatment of galena, with the object of removing the
sulphur, or the greater portion thereof, prior to subjecting the ore to smelting or other
reduction process; the excess of sulphur eliminated being collected as sulphurous-acid.
and utilised in. the manufacture of sulphuric acid or otherwise.
In carrying out our improved method of treatment, we mix with .sulphide of lead
ore, or galena, (unless already present therein) an oxide of an alkaline earth-as, for
instance, calcium oxide; the proportion of oxide we usually find it desirable to add
corresponding with the proportion of sulphur present in the ore. The mixture is then
placed in a reverberating furnace and raised to a dull red heat. By means of a
blower or equivalent apparatus, atmospheric,air, which, may have been previously
heated, is then forced or drawn through the heated mass; whereupon the sulphur
present. in the. ore combines with the oxygen conveyed by the. air, combustion takes
place, and, without any additional fuel, an intense heat is generated, and a large
volume of concentrated sulphurous, acid gas is given off. This may be collected and
applied in the manufacture of sulphuric acid or otherwise utilised. At the same time,
a reaction takes place between the calcium oxide and the sulphide of lead; a portion
of the sulphur contained in the, latter becoming absorbed, by the calcium base, calcium.
sulphate resulting.
As the result, of this method of treatment, the sulphide, of lead. originally present in
the ore is converted into oxide of lead. This, together.with its gangue matter and
calcium sulphate, is transferred. to a blast or other furnace for the reduction of the
metallic lead..
COMPLETE SPECIFICATION.
Improvements in the Treatment of Sulphide Ores of Lead
Preparatory to Smelting the same, and Incidentally in.
Obtaining Sulphurous Acid.
We, THOMAS HUNTINGTON and FERDINAND HEBERLEIN, both of Pertusola, near
Spezzia, in the Kingdom of Italy, Metallurgical Engineers, 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:-
This invention relates to the treatment of galena or lead sulphide, with the object-

page_text: of removing the sulphur, or the greater portion thereof, prior to subjecting the ore to
smelting or other reduction process; the excess of sulphur eliminated being collected
as sulphurous acid and utilised in the manufacture of sulphuric acid or otherwise.
In treating sulphide of lead ore or galena according to our invention, we mix with
the ore (unless already present therein) a certain quantity of an oxide of an alkaline
earth metal-as, for instance, calcium oxide-proportionate to the sulphur present in
the ore, and subject the mixture in a reverberatory or other suitable furnace to the
action of a dull red heat (say, 500° C.), the mixture having, by preference, been
previously steadily raised to say 700° C. and allowed to slowly assume the former
temperature, with the result that a reaction of calcium dioxide upon the galena and
the formation of sulphate of lead commences. At this stage, the mixture is removed
to a receptacle, wherein it is exposed to the action of a current of atmospheric air,
which may have heen previously heated, and which may be forced or drawn through
the mass by means of a blower or equivalent apparatus. The sulphur present in the
ore combines with the oxygen conveyed by the air, combustion takes place, and,
without any additional fuel, an intense heat is generated, and a large volume of
concentrated sulphurous acid gas is given off. The mixture fuses and gradually
settles down to a mass of oxide of lead with the gangue matters of the ore. It is then
ready for further treatment in a blast furnace or otherwise for the reduction of the
metal. The sulphurous acid may be collected and applied in the manufacture of
sulphuric acid or otherwise utilized.
In the treatment of sulphide of lead ore or galena, as hereinbefore described, we.
have found that by subjecting an intimate mixture of calcium oxide and galena to a
dull red heat (say 500° C.), the said mixture having previously been steadily raised
to a bright red heat (say 700° C.), whereby, as we believe, the oxide (CaO) absorbs
oxygen and forms calcium dioxide (CaO,), decomposition takes place, calcium oxide.
and oxygen resulting. This nascent oxygen appears to attack the sulphide of lead
energetically, to oxidise it, and to convert part of it into oxide (PbO) and sulphate of
lead (PbSO), considerable heat being generated. At this point; by forcing a strong
current of air (which may have been previously heated) through the said mixture, the
operation of conversion becomes continuous, and the heat is maintained at such a point
that reaction takes place between the sulphides and sulphates; the oxygen acting
upon the galena so long as any sulphur remains in the mixture. Concentrated fumes
of sulphurous acid are given off, and the mixture gradually fuses to a mass of lead
oxide, in conjunction with the gangue matter of the ore treated. The product thus
obtained may be treated in any known manner for the reduction of the metal.
Assuming the reactions which take place to be such as we suggest, the above
mentioned phases of the process are represented by the following formula:-
1 at 7000 A
It will be seen that, as the result of this method of treatment, the sulphide of lead
originally present in the ore is converted into oxide of lead; which, with its gangue
matter and calcium sulphate, may then be transferred to a blast or other furnace for
the reduction of the metallic lead.
Having now particularly described and ascertained the nature of this invention
and in-what manner the same is to be performed, we claim :-
1. The herein described method of treating sulphide ores of lead, preparatory to
reduction to metal, which consists in mixing with the ore to be treated the oxide of
an alkaline earth metal, heating the mixture in a reverberatory or other suitable
furnace to a dull red heat, and then forcing air through the mass, substantially as
herein described, oxide of lead resulting.

page_text: 2. The herein described method of treating sulphide ores of lead preparatory to
reduction to metal, which consists in mixing with the ore to be treated the oxide of an
alkaline earth metal, subjecting the mixture to heat in the presence of air, whereby
the oxide is converted into dioxide, then reducing the temperature whereby the said
dioxide is caused to yield up a portion of its oxygen to the lead and finally passing air
through the mass to complete the oxidation of the lead, substantially as and for the
purpose set forth.
3. The herein described method of treating sulphide.ores of lead preparatory to.
reduction to metal, which consists in mixing the oxide of an alkaline earth metal-
preferably calcium oxide-with the ore to be treated, subjecting the mixture in the
presence of air to a temperature of about 700° C., then cooling down the mixture to
about 500° C., and finally forcing air through the mass until the lead ore, reduced to
an oxide, fuses, substantially as set forth.
4. The herein described method of reducing lead sulphide to lead sulphate, in the
preparation of the sulphide for reduction to metal, which consists in subjecting the
sulphide to a high temperature in the presence of an oxide of an alkaline earth metal
and oxygen, whereby said oxide takes up oxygen and is converted into dioxide, and
then lowering the temperature until the latter yields the portion of its oxygen taken.
up to combine with the sulphur in the ore, substantially as set forth.
Dated this 15th dan of Tobruo 1907