Improvements in the Apparatus and Method employed in the Production of Lead Oxide and the Treatment of Rough Litharge.
Year: 1898

page_text: Date of Application, 17th Oct., 1898
Complete Specification Left, 17th July, 1899-Accepted, 17th Oct., 1899
PROVISIONAL SPECIFICATION.
Improvements in the Apparatus and Method employed in the
Production of Lead Oxide and the Treatment of Rough Litharge.
We, MATTHEWS' LANCASHIRE, CHESHIRE, AND NORTH WALES DISTRICT WHITE
LEAD COMPANY LIMITED, Manufacturers of White Lead, SAMUEL POPE,
Manager of the said Company, and GEORGE VINCENT BARTON, Secretary to the
said Company, all of Old Quay, Runcorn, in the County of Cheshire, do hereby
declare the nature of this invention to be as follows:-
The invention relates to improvements in the apparatus and method employed
in the production of lead oxide, and the treatment of rough litharge.
In carrying the invention into effect a covered pot or vessel formed of iron
or other suitable material is employed, provided with a gas or other furnace cap-
able of efficiently heating the lead to be treated, and a quantity of lead is from
time to time introduced into the pot and by the furnace maintained in the re-
quired fluid state.
In a suitable position at the side of the pot and above the molten lead is pro-
vided an outlet consisting of an upwardly inclined shoot arranged either radially
or tangentially, and this outlet communicates with suitable collecting vessels
for the lead oxide hereinafter more fully referred to, and extending either
radially or tangentially from the wall of the pot at the rear side of the said
outlet towards or if desired beyond the centre of the pot is arranged a suitably
shaped baffle plate or curtain, which is preferably adjustable and extends nearly
to the bottom of the pot or to such position as will enable it to scrape the sur-
face of the lead when the latter is in motion as hereinafter described.
At or near the bottom of the pot and beneath the baffle plate or curtain is
provided a horizontal paddle or stirrer which is fixed upon a vertical shaft receiv-
ing rotary motion at a regulated speed from any suitable source of power and this
stirrer dashes the molten lead against the baffle plate or curtain in front of the
outlet.
Instead of a single paddle or stirrer two or more of such stirrers may be be
employed if required.
:
The molten metallic lead carried round by the stirrer forms a kind of wave,
the crest of which runs up the sides of the pot, and portions of this metal are
liable to become 'detached and carried over the walls of the pot and also through
the outlet into the receiving or collecting chambers.
In order to obviate this difficulty an annular horizontal flange or projection is
provided extending around the pot or vessel on the interior thereof on a level
with or slightly below the bottom of the outlet by which means the wave will
be kept properly under control.

page_text: As a further precaution the outlet leading from the pot to the receiving
chambers is surrounded by a flange or projection which effectually prevents the
metallic lead rising sufficiently at that point to be carried into the receiving
chambers.
At suitable intervals around the interior of the pot are arranged vertical pro-
jections or baffle plates which serve to prevent the wave unduly rising, and at the
same time break up the wave as hereinafter described.
By reason of the inclined position of the shoot or outlet from the pot any
molten metallic lead' which may be accidentally carried through the outlet will
flow back by gravity into the pot.
Above the surface of the molten lead is arranged a pipe which is perforated
at intervals and formed' with an open but flattened end and extends horizontally
from the rear side of the baffle plate or curtain in a circular, form partly around
the pot and terminates at some distance from but with its open flattened end
pointing towards the baffle plate or curtain and this pipe is supplied with com-
bined heated air and super-heated steam under pressure, for example by the
aid of a vena contracta or other suitable means.
The perforations in the pipe are preferably arranged at such an angle as to
cause the issuing steam and air to impinge upon the molten lead and at the
same time travel in the direction of the outlet from the pot.
If desired the lateral perforations in the pipe may be dispensed with whilst
retaining the flattened mouth thereto.
Or separate pipes for the air and steam, or several sets of pipes might be
employed.
In order to produce lead oxide by the means hereinbefore described the furnace
is started and the pot is charged with a suitable quantity of lead which is main-
tained in a molten condition by the furnace, the stirrer is then set in motion
at a suitable speed of rotation and the supply of heated air and super-heated
steam under pressure is admitted by the perforated pipe and impinges upon the
surface of the molten lead, by which means said surface becomes coated with a
film of oxide which is carried round with the lead until its progress is arrested
by the baffle plate or curtain, the film of oxide near its periphery being at the
same time broken up by the vertical baffle plates.
1
The wave of lead at the same time coming into contact with the vertical baffle
plates causes very violent turbulence and the pulverisation of the lead striking
said baffle plates, thus shaking and loosening the oxide' from the metallic lead
and causing it to be more easily carried forward into the receiving chambers as
hereinafter described.
The lead and oxide are brought into contact with the baffle plate or curtain
with some degree of force and their impact therewith causes the oxide to rise in
a cloud which is controlled by the baffle plate or curtain and deflected towards
the outlet through which it is carried by the current of air and steam to suitable
receiving or collecting chambers where the oxide is deposited in the form of an
impalpable powder of great purity.
The baffle plate or curtain scrapes the surface of the lead and frees it from
oxide, leaving that part of the surface beyond the baffle plate or curtain clean for
the current of air and steam to act upon.
The heating of the air and super-heating of the steam to a suitable tempera-
ture is of very great importance and amongst other things prevents the chilling
and consequent accumulation of splashes of metallic lead upon the walls of the
pot in the mouth of the outlet and in other places.
In the same manner mixed rough litharge may be converted into fine lead
oxide, thus avoiding the operations of grinding and levigation to free the lead
oxide from the metallic lead usually intermixed therewith when lead' oxide is
produced by the old method of cupellation.
For this purpose a charge of the mixed rough litharge is introduced into the
pot and floats upon the surface of the molten lead the apparatus is put in action,

page_text: the oxide is caught by the curtain, and under the combined influence of the
stirrer, steam and air, and baffle plates and curtain is reduced to a fine state of
division and carried into the receiving chambers where it is collected in a state
of fine powder ready for use.
Any metallic lead in the rough litharge is liquefied by the heat maintained
in the pot or vessel and becomes oxidised and by these means the whole of
the rough litharge is recovered as a fine powder of lead oxide.
WHITE & WOODINGTON,
Rooms 221-225, Birkbeck Bank Chambers,
Southampton Buildings, London, Agents.
Improvements in the Apparatus and Method employed in the
Production of Lead Oxide and the Treatment of Rough Litharge.
We, MATTHEWS' LANCASHIRE, CHESHIRE, AND NORTH WALES DISTRICT WHITE
LEAD COMPANY LIMITED, Manufacturers of White Lead, SAMUEL POPE, late
Manager of the said Company, and GEORGE VINCENT BARTON, Secretary to the
said Company, all of Old Quay, Runcorn, in the County of Cheshire, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed to be particularly described and ascertained in and by the following
statement, reference being had to the drawings hereunto annexed and to the
figures and letters marked thereon that is to say:-
―
The invention relates to improvements in the apparatus and method employed
in the production of lead oxide and the treatment of rough litharge, and the
primary object thereof is to obtain lead oxide in a more rapid and economical
manner than heretofore.
In the accompanying drawings,
Figure 1 is a vertical longitudinal section representing a plant for carrying
the said invention into effect.
Figure 2 is a plan thereof with part removed.
Figure 3 is a vertical transverse section taken on the line 1-1 of Figure 1.
Figure 4 is a front end elevation of the apparatus with the pot removed.
Figure 5 is a rear end elevation thereof partly in section.
Figure 6 is a front elevation of the covered pot or vessel separately.
Figure 7 is a plan thereof.
Figure 8 is a side elevation thereof partly in section.
Figure 9 is a rear elevation thereof.
Figure 10 is a horizontal section taken on the line 2-2 of Figure 8.
Figure 11 is a horizontal section taken on the line 3-3 of Figure 9 and with
the paddle or stirrer removed, and
Figure 12 is a vertical transverse section showing the upper part of the pot
separately.
In the several figures in which like parts are indicated by similar letters of
reference Figures 4 and 5 are drawn to an increased scale with respect to
Figures 1 to 3 whilst Figures 6 to 12 are drawn to a still further increased
scale.
Referring to the drawings a represents a closed pot or vessel & represents a
furnace for heating the same e represents a collecting chamber for the oxide
and f g h represents an apparatus for trapping the lighter particles of oxide
and preventing their escaping into the outer air.

page_text: The pot or vessel a is formed of iron or other suitable material capable of
withstanding the heat to which it is subjected and the furnace d which may be
a coal gas or other suitable furnace must be capable of efficiently heating the
lead to be treated and which is contained in the pot a.
The pot a is furnished at its rear with two openings a¹ a³ closed by means of
suitable covers, one of said openings namely that a serving as a manhole and
the other a serving as a feed opening through which a quantity of fused lead
is from time to time introduced into the pot a said lead being afterwards main-
tained by the furnace in the required fluid state.
At the rear side of the pot a and above the molten lead is provided an outlet a³
to which is connected an upwardly inclined shoot a which if desired might be
arranged tangentially to the pot a and this shoot a communicates with the
collecting chamber e hereinafter more fully referred to.
Extending tangentially from the wall of the pot a at the rear side of the out-
let a³ to the centre of the pot a or it might be beyond is a suitably shaped baffle
plate or curtain as which terminates in an apertured boss a formed on the
upper part of the pot a and this curtain or baffle plate a extends downward to
a suitable position as hereinafter described.
At or near the bottom of the pot a and beneath the baffle plate or curtain a
is provided a horizontal paddle or stirrer 6 which is fixed upon a vertical shaft b¹
passing through the apertured boss a which forms a bearing to the shaft and
at its upper end said shaft is mounted in a bearing 63 supported by a frame b³
carried by the upper part of the pot a.
The vertical shaft 6 and consequently the paddle or stirrer 6 receive rotary
motion at a regulated speed through a bevelled toothed wheel 6 fixed upon the
vertical shaft 61 which engages a bevelled pinion 66 fixed upon a horizontal
shaft 65 at its ends mounted in bearings 67 carried by the frame and furnished
with fast and loose pulleys 68 by means of which the shaft 61 and paddle b may
be driven from any suitable source of power.
The paddle or stirrer 6 which revolves in the direction of the arrow Figure 10,
or there might be several stirrers as will be readily understood, carries round with
it the molten metallic lead which forms a kind of wave the crest of which dashes
against the baffle plate or curtain a5 said action taking place in front of the
outlet a³.
The crest of this wave runs up the sides of the pot a and portions of the metal
are liable to become detached and by the blast hereinafter referred to, carried
up the walls of the pot a and through the outlet a³ into the receiving or collect-
ing chambers e.
In order to obviate this difficulty an annular horizontal flange or projection a
is provided extending around the pot or vessel a on the interior thereof on a
level with or slightly below the bottom of the outlet a³ by which means the
wave will be kept properly under control.
As a further precaution the outlet a leading from the pot to the receiving
chambers e is surrounded by a flange or projection as which effectually prevents
the metallic lead rising sufficiently at at that point to be carried into the collecting
chamber e.
At suitable intervals around the interior of the pot a are arranged vertical
projections or baffle plates a which serve to prevent the wave of lead unduly
rising and at the same time assist to break up the same as hereinafter described.
By reason of the inclined position of the shoot at leading from the outlet a³
of the pot any molten metallic lead which may be accidentally carried through
the outlet a will flow back by gravity into the pot a instead of being carried
into the chambers e.
Above the surface of the molten lead is arranged a pipe c which is formed
with an open but downwardly curved end c¹ and this pipe extends horizontally
from the rear side of the baffle plate or curtain a³ in a circular or curved form so
that its open end c¹ points in the direction in which the molten lead or the sur-

page_text: face thereof is required to travel and this pipe c is supplied with combined
heated air and super heated steam under pressure for example by the aid of a
vena contracta c³ placed in the pipe c and into which enters a pipe ³ supplied
with super-heated steam under pressure from any suitable source.
The pipe c is similarly supplied with heated air and the blast of combined
heated air and super-heated steam issuing from the mouth c¹ of the pipe c is
caused to impinge upon the surface of the molten lead and at the same time
travel in the direction of the outlet a³ from the pot a.
It will be understood that instead of the arrangement shown in the drawings
any other suitable contrivance or contrivances might be employed for conveying
a blast of heated air and super-heated steam either combined or not onto the
surface of the metal.
In order to produce lead oxide by the means herein before described the fur-
nace d is started and the pot a is charged through the feed opening a³ with a
suitable quantity of fused metallic lead which is maintained in a molten condition
by the furnace d.
The paddle or stirrer b is then set in motion at a suitable speed of rotation
through the pulleys 68 herein before referred to and the supply of heated air and
super-heated steam under pressure is admitted by the pipe c and impinges upon
the surface of the molten lead by which means said surface becomes coated with
a film of oxide which is carried round by the lead which assumes a wave like
form its crest coming against the baffle plate or curtain as the film of oxide near
the periphery of the pot being at the same time broken up by the vertical baffle
plates a³.
The wave of lead at the same time coming into contact with the vertical baffle
plates a causes very violent turbulence and the pulverisation of the' lead striking
said baffle plates a thus shaking and loosening the oxide from the metallic. lead
and causing it to be more easily carried forward through the opening a³ into the
receiving or collecting chambers e as hereinafter described.
The lead and oxide are brought into contact with the baffle plate or curtain a³
with some degree of force and their impact therewith causes the oxide to rise in
a cloud which is controlled or directed by the baffle plate or curtain a³ and de-
flected towards the outlet a³ through which and through the shoot at it is carried
by the blast or current of air and steam into the receiving or collecting chambers
or apparatus e f g h hereinafter more fully referred to where the oxide is
finally deposited in the form of an impalpable powder of great purity.
The heating of the air and superheating of the steam to a suitable temperature
is of very great importance and amongst other things prevents the chilling and
consequent accumulation of splashes of metallic lead upon the walls of the pot a
in the mouth of the outlet a³ and in other places.
The cloud of oxide passing through the shoot-a" is carried by the blast into the
first of a series of collecting chambers e which communicate with one another
by openings e at the upper part thereof, and these chambers are at their lowest
point furnished with openings e closed by doors by means of which the deposited
oxide may be removed from time to time.
The oxide entering the chambers through the shoot at is deposited in the
collecting chambers according to its specific gravity as is well understood and the
lighter particles are carried through the end opening e¹ into a trunk or
chamber which at its lower end opens into a tub g containing water and near
to its lower end by means of a lateral connection f communicates with a vertical.
pipe the lower end of which is immersed in the water of the tub g and which
at its upper end opens into the lower end of a barrel furnished with a number.
of inclined. and overhanging shelves or baffle plates 2 onto which water is.
allowed to flow in regulated quantities from a cock supplied by a pipe i con-
nected with any convenient reservoir of water.
By means of this device the lighter particles of oxide which do not become de-

page_text: posited in the chambers e pass into the trunk f and the heavier particles are
carried by tlie blast into the water of the tub whilst the lighter particles pass
by the connection f into the pipe where on entering the barrel h¹ they
encounter and are required to pass through the circuitous passage between the
shelves and which are covered by a film of water which flows from shelf to
shelf and the escaping blast of steam and air to some extent atomises the water
so that it is virtually impossible for any portion of the oxide to escape into the
open air and the process is thus rendered comparatively harmless.
The oxide deposited in the tub g is removed and submitted to the usual final
processes to render it marketable or for the production of white lead.
In the same manner mixed rough litharge may be converted into fine lead
oxide thus avoiding the operations of grinding and levigation to free the lead
oxide from the metallic lead usually intermixed therewith when lead oxide is
produced by the old method of cupellation.
For this purpose a charge of the rough litharge is introduced into the pot a
and floats upon the surface of the molten lead the apparatus is put into action
the oxide is caught by the curtain a³ and under the combined influence of the
stirrer b heated air and superheated steam and baffle plates a⁹ and curtain a³ is
reduced to a fine state of division and carried into the collecting apparatus where
it is recovered in a state of fine powder ready for use.
Any metallic lead in the rough litharge is liquefied by the heat maintained in
the pot or vessel a and becomes oxidized and by these means the whole of the
rough litharge is recovered as a fine powder of lead oxide.
+
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed we declare that what
we claim is :-
1. A process for the production of lead oxide consisting in maintaining a
quantity of metallic lead in a fused state in a closed pot or vessel, stirring said
lead, directing a blast of heated air and superheated steam upon the surface
of the fused lead so as to oxidize the same and by means of said blast carrying
the oxide thus produced through an opening in the wall of the vessel into suit-
able collecting or grading chambers substantially as herein shown and described.
.2. A process for the production of lead oxide consisting in maintaining a
quantity of metallic lead in a fused state in a closed pot or vessel provided with
an outlet to a collecting chamber stirring said fused lead in one direction,
directing a blast of heated air and superheated steam upon the surface of the
fused lead so as to oxidize the same and by means of a baffle plate or curtain
arresting the moving film of oxide in front of said outlet so that it will be
caught by the blast and carried through the outlet into the collecting chambers
substantially as herein shown and described.
3. A process for the production of lead oxide from rough litharge consisting
in maintaining a quantity of metallic lead in a fused state in a closed pot or
vessel provided with an outlet to a collecting chamber, stirring said fused lead
introducing a charge of rough litharge thereon directing a blast of heated air
and superheated steam upon the rough litharge on the surface of the fused lead
and by means of said blast carrying the oxide thus produced through the outlet
into the collecting chambers substantially as herein shown and described.
4. An apparatus for the production of lead oxide comprising a closed pot or
vessel adapted to contain a charge of lead, means for heating said pot, a collect-
ing chamber, an outlet from the pot, an inclined connection between the outlet
and the collecting chamber, a flange surrounding said outlet means for directing
an oxidizing blast onto the surface of the fused lead, a paddle or stirrer within
the pot, means for rotating the paddle, a horizontal annular flange located above
the surface of the lead, vertical baffle plates arranged at intervals around the

page_text: pot and a baffle plate or curtain projecting laterally from the rear side of the
outlet towards the centre of the pot and extending downwardly into a position
to catch the film of oxide substantially as herein shown and described and for
the purpose stated.
Dated this 17th day of July 1899.
WHITE & WOODINGTON,
Rooms 221-225, Birkbeck Bank Chambers,
Southampton Buildings, London, Agents.