Improvements in Apparatus for Reducing Litharge and other Lead Oxides to Suboxide.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Reducing Litharge and other Lead
Oxides to Suboxide.
I, GUSTAV BISCHOF, of Hythe Road, Willesden Junction, in the County of London,
Professor, do hereby declare the nature of this invention to be as follows:-
In my Specification No. 11602 of 1890 I have described a process for the manufac-
ture of white lead, the first operation of which is the reduction of litharge, and other
lead oxides which may be mixed with it to the condition of a suboxide probably
corresponding to the formula Pb20, which is afterwards treated for production of
white lead.
My present invention relates to apparatus for effecting this reducing operation in
a simple and inexpensive manner.
For this purpose I provide a vertical cylindrical vessel enclosed in an outer vessel
of larger diameter forming between them an annular space in which gas is burned so
as to maintain the inner vessel at a temperature of 250° to 300° C. The vessel is
closed at the top, and the cover is provided with a feed hopper from which a shoot
leads some distance down into the inner vessel.
There is also near the bottom of the vessel an inlet for water gas supplied from
a compressor, and at the top there is an outlet pipe leading to a gas holder. At the
bottom of the vessel there is a discharge passage tapering to an outlet of smaller
diameter, and this passage is surrounded by a jacket through which cooling water
circulates.
Down the centre of the vessel extends a spindle carrying blades so inclined that, as
the spindle revolves, they tend to raise the material in the vessel; and in the tapering
outlet at the bottom there are agitating blades on the spindle.
The apparatus is worked as follows:-
The vessel being heated and the spindle caused to revolve, the litharge which may
consist more or less of oxides other than PbO is fed by the hopper and shoot. . The
material is raised by the revolving blades above the mouth of the shoot, so as to seal
it against the escape of gas. Water gas is forced into the vessel at sufficient pressure
to cause it to pass upwards through the material and the gas, after giving up part of
its hydrogen to oxygen from. the oxides along with the steam resulting from the
combination of the oxygen and hydrogen passes a gas holder, from which the
freed from steam by condensation can be used again for reduction of the litharge or
for other purposes. The material reduced to condition of suboxide is cooled as it
descends the tapering outlet, portions of it being from time to time let out by opening
a valve at the bottom, or being continuously removed by an eccentrically mounted
disc revolving under the outlet orifice and under a fixed scraper.
gas
In order to ascertain the temperature in the reducing vessel, I prefer to make the
spindle tubular so that a suitable thermometer may be introduced into its hollow.
When a single compressor is employed to supply several reducing vessels with reducing
gas I provide in the pipe leading to each vessel an indicator of flow consisting of a
blade in the pipe fixed on a spindle which passes through a stuffing box and carries

page_text: an index outside shewing by its deflection that there is flow of gas through the pipe,
or indicating when it is in zero position that the pipe is choked.
Dated this 13th day of June 1898.
ABEL & IMRAY,
Agents for the Applicant.
"
Improvements in Apparatus for Reducing Litharge and other Lead
Oxides to Suboxide.
I, GUSTAV BISCHOF, of Hythe Road, Willesden Junction, in the County of London,
Professor, 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:
In my Specification No. 11602 of 1890 I described a process for the manufacture of
white lead, the first operation of which is the -reduction of litharge and other lead
oxides which may be mixed with it to the condition of suboxide probably having the
formula Pb20, which is afterwards treated for production of white lead. My present
invention relates to apparatus for effecting the reducing operation in a simple and
inexpensive manner, as I shall describe referring to the accompanying drawings,
Fig. 1 of which is a vertical section and Fig. 2 a sectional plan on line 2-2 of
apparatus according to my invention.
A is a vertical cylindrical vessel enclosed in an outer vessel B of larger diameter,
forming between them an annular space C, in which gas is burned from burner H so
as to maintain the temperature of the vessel A at 250° to 300° C.
The cover of A is provided with a feed hopper D from which a shoot d leads some
distance down.
Near the bottom of A is an inlet E for pure water gas supplied by a compressor,
and at the top is an outlet e leading to a suitable dust collector and a gas holder.
The bottom of A tapers so as to form a discharge passage a leading to an outlet of
smaller diameter, and the passage a is surrounded by a jacket through which cooling
water circulates. Down the centre of A extends a revolving spindle F carrying blades f
which are so inclined that, as they revolve, they tend to raise the material in A, and
in the passage a the spindle has blades which serve to agitate. At the bottom of
the tapering passage a is an outlet opening closed by a loaded valve G.
The apparatus is worked as follows:
The vessel being heated and the spindle caused to revolve, the litharge which may
consist more or less of oxides other than Pb.O is fed by the hopper D and shoot d.
The material is raised by the revolving blades f above the mouth of the shoot d, so
as to seal it against the escape of gas.
Water gas, free froin sulphur compounds, is forced into the vessel at E under
sufficient pressure to cause it to pass upwards through the material, and the gas, after
giving up part of its hydrogen to oxygen liberated from the lead oxides along with the
steain resulting from the combination of the oxygen and hydrogen passes first to a
dust collector and then to a gas holder, from which the gas freed from steam by
condensation can be used again for reduction of the litharge or for other purposes.
The material reduced to condition of suboxide, probably Pb.20, is cooled as it
descends the tapering passage a, portions of it being let out by opening the valve G,
preferably by means of a revolving cam g which opens the outlet at intervals.
The spindle F is preferably tubular so that a suitable thermometer can be inserted
to shew the temperature within the vessel A.

page_text: When several such vessels are supplied with water gas, from a single compressor, I
prefer to provide the supply pipe E of each with an indicator of flow, consisting of a
blade E¹ pivotted within the pipe on a spindle which passes through a stuffing box and
carries an external index.
When gas continues to flow through the pipe the blade E¹ is deflected and this is
shewn by the deflection of the external index. When the pipe is choked, where it
enters A, the blade El hangs vertically, and the index shews that there is no flow.
Having now particularly described and ascertained the nature of this inven-
tion and in what manuer the same is to be performed, I declare that what
I claim is
Apparatus for reducing litharge and other lead oxide to suboxide constructed and
operating substantially as described with reference to the drawings.
D
ي فم
1000
ABEL & IMRAY,
Agents for the Applicant.