An Improved Method or Process for the Direct Smelting of Sulphide Lead Ores, and the like.
Year: 1898

page_text: Date of Application, 27th Aug., 1898
Complete Specification Left, 23rd Feb., 1899-Accepted, 15th Apr., 1899
PROVISIONAL SPECIFICATION.
An Improved Method or Process for the Direct Smelting of Sulphide
Lead Ores, and the like.
I, ERMINIO FERRARIS, of 42, Freiestrasse, Zürich, in the Republic, of Switzer-
land, Engineer, do hereby declare the nature of this invention to be as follows:-
This invention has for its object a method or process for the desulphurisation of
crude lead ores, zinc-lead sulphide ores and mattes directly in the blast furnace
without previous roasting which method avoids the production of mattes and
speiss and utilises the heat evolved by the combustion of sulphur.
The furnace which is better suited to this purpose is a kind of the Rachette shaft
furnace, but the process may also advantageously be applied to any kind of lead
blast furnace supplied with a lead bath and automatic tap.
In the section of the furnace shown in the accompanying drawing, the crucible A
is deeper than usual and lined with firebricks of proper size, surrounded by boiler
plates, fitted out with an automatic tap.
The tuyères are placed on the two opposite long sides of the furnace and bolted
on two straight cast iron pieces B which are at back and front bound together
by two front plates of cast- or wrought iron.
The pieces B rest upon the wall of the crucible and bear the inclined walls
of the smelting zone.
The size of the furnace and the number of the tuyères depend on the capacity
required, but the width of the furnace between the tuyères ought not to exceed Im.
or forty inches in order to avoid a strong reducing zone in the centre, which the
blast cannot easily reach.
To complete a good separation of slag and matte, the level of the tuyères is kept
a little higher than usual over the slag hole a.
The cooling of the iron lining of the smelting zone is performed by a sheet of
continually running water thrown from perforated water pipes 6 placed on the
side of the lining; care must be taken not to cool the lining more than is strictly
necessary to preserve the walls. If the water is almost pure it would be preferable
to employ water jacketted tuyères instead of the open pieces B.
The limitation in cooling permits of a sparing of fuel and of the atmosphere
of the furnace being kept as oxidising as possible in order to burn in the shaft a
part of the sulphur of the charge.
The undecomposed sulphides which pass through the smelting zone would form
a layer on the lead of the crucible, drive out the metal and obstruct the automatic
tap, if the means of obviating it were not at hand as described hereafter.
The present invention aims precisely at the reduction of these sulphides into
metal and consists in the introduction of compressed air into the molten lead.
In the masonry of the crucible one or more holes are provided reaching the
bottom of the crucible; into these are collocated cast iron pipes C ending upwards
with a T pipe d for coupling it with the flexible air pipe D. Generally the cast
iron pipes are joined together by a transversal pipe, into which the air pipe has
to be introduced.

page_text: For setting the apparatus to work, the holes C are opened, and after having
ascertained that the lead is moving freely in the tube compressed air is let in
and the pipe closed with a wooden plug e.
The air at a pressure a little more than one atmosphere enters the lead and
when this is hot enough oxide of lead will be formed which will react upon the
sulphide of lead thus liberating metallic lead and evolving sulphurous acid, which
together with the azote will find its passage through the molten slag.
The air is to be introduced in moderate quantity and as soon as the overflowing
lead shows the characteristic play of colours of soft lead, the introduction of air
must be stopped.
Any excess of air would cause a superoxidation of the ferrous oxide of the slag,
which would get pasty and less fusible and overheating of the lead in the crucible
would cause a great loss of metal by volatilisation.
The advantages of the present invention compared with other systems now in
use in the smelting of lead ores are as follows:-
a) The possibility of smelting the ores in a direct way by means of the blast
furnace, without previous crushing and roasting of the ores.
Ores of fine size may be submitted to the same process provided that they have
been previously shaped into briquettes, by the addition of lime.
b) Utilisation of the heating power of the sulphur and consequent diminution
in the consumption of fuel.
c). Better running of the furnace on account of the energetical stirring produced
by the compressed air which avoids the formation of accretions in the crucible.
If the charge contain copper a rich copper matte will result and flow out
automatically with the lead.
If no copper is present only poor slags and base bullion will result.
Dated this 26th day of August 1898
WM. P. THOMPSON & Co.,
Of G, Lord Street, Liverpool, Agents for the Applicant.
An Improved Method or Process for the Direct Smelting of Sulphide
Lead Ores, and the like.
I, ERMINIO FERRARIS, of 42, Freiestrasse, Zurich, in the Republic, of Switzer-
land, Engineer, 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 has for its object a method or process for the desulphurisation of
crude lead ores, zinc-lead sulphide ores and mattes directly in the blast furnace
without previous roasting which method avoids the production of mattes and
speiss and utilises the heat evolved by the combustion of sulphur.
The furnace which is better suited to this purpose is a kind of the Rachette shaft
furnace, but the process may also advantageously be applied to any kind of lead
blast furnace supplied with a lead bath and automatic tap.
In the section of the furnace shown in the drawing accompanying the Provisional
Specification the crucible A is deeper than usual and lined with firebricks of
proper size surrounded by boiler plates, fitted out with an automatic tap.
The 'tuyères are placed on the two opposite long sides of the furnace and bolted
on two straight cast iron pieces B which are at back and front bound together
by two front plates of cast or wrought iron,

page_text: The pieces B rest upon the wall of the crucible and Dear the inclined was
of the smelting zone.
The size of the furnace and the number of the tuyères depend on the capacity
required, but the width of the furnace between the tuyères ought not to exceed 1m.
or forty inches in order to avoid a strong reducing zone in the centre, which the
blast cannot easily reach.
To complete a good separation of slag and matte, the level of the tuyères is kept
a little higher than usual over the slag hole a.
b
The cooling of the iron lining of the smelting zone is performed by a sheet of
continually running water thrown from perforated water pipes 6 placed on the
side of the lining; care must be taken not to cool the lining more than is strictly
necessary to preserve the walls. If the water is almost pure it would be preferable
to employ water jacketted tuyères instead of the open pieces B.
The limitation in cooling permits of a sparing of fuel and of the atmosphere
of the furnace being kept as oxidising as possible in order to burn in the shaft a
part of the sulphur of the charge.
The undecomposed sulphides which pass through the smelting zone would form
a layer on the lead of the crucible, drive out the metal and obstruct the automatic
tap, if the means of obviating it were not at hand as described hereafter.
The present invention aims precisely at the reduction of these sulphides into
metal and consists in the introduction of compressed air into the molten lead.
In the masonry of the crucible one or more holes are provided reaching the
bottom of the crucible; into these are collocated cast iron pipes C ending upwards
with a T piped for coupling it with the flexible air pipe D. Generally the cast
iron pipes are joined together by a transversal pipe, into which the air pipe has
to be introduced.
For setting the apparatus to work, the holes C are opened, and after having
ascertained that the lead is moving freely in the tube, compressed air is let in
and the pipe closed with a wooden plug e.
The air at a pressure a little more than one atmosphere enters the lead and
when this is hot enough oxide of lead will be formed which will react upon the
sulphide of lead, thus liberating metallic lead and evolving sulphurous acid, which
together with the azote will find its passage through the molten slag.
The air is to be introduced in moderate quantity and as soon as the overflowing
lead shows the characteristic play of colours of soft lead, the introduction of air
must be stopped.
Any excess of air would cause a superoxidation of the ferrous oxide of the slag,
which would get pasty and less fusible and overheating of the lead in the crucible
would cause a great loss of metal by volatilisation.
The advantages of the present invention compared with other systems now in
use in the smelting of lead ores are as follows:-
a) The possibility of smelting the ores in a direct way by means of the blast
furnace, without previous crushing and roasting of the ores.
Ores of fine size may be submitted to the same process provided that they have
been previously shaped into briquettes by the addition of lime.
6) Utilisation of the heating power of the sulphur and consequent diminution
in the consumption of fuel.
c) Better running of the furnace on account of the energetical stirring produced
by the compressed air which avoids the formation of accretions in the crucible.
d) If the charge contain copper a rich copper matte will result and flow out
automatically with the lead.
If no copper is present only poor slags and base bullion will result.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:
The method or process of smelting sulphide lead ores in the blast furnace

page_text: characterised by compressed air being introduced into the bath of lead produced in
the ordinary manner by smelting the charge of ore with coal, with the object of
decomposing the sulphide, formed above the lead bath, by means of the lead oxide
formed by the compressed air substantially as herein before described.
Dated this 22nd day of Februarr 1800
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Agents for the Applicant.