IMPROVED MEANS AND APPARATUS FOR FACILITATING THE DISSOLUTION OF METALLIC LEAD OR OF OXIDE OF LEAD IN THE MANUFACTURE OF WHITE LEAD to be as follows:
Year: 1884

page_text: PROVISIONAL SPECIFICATION.
I, ALEXANDER WILLIAM ANDERSON of Old Kent Road in the County of 'Surrey,
do hereby declare the nature of my invention for "IMPROVED MEANS AND
APPARATUS FOR FACILITATING THE DISSOLUTION OF METALLIC LEAD OR OF OXIDE
OF LEAD IN THE MANUFACTURE OF WHITE LEAD to be as follows:-
"
My invention relates to means and apparatus for facilitating the dissolution of
metallic lead or of oxide of lead by the action of acetic or other suitable solvent
acid or chemical in the manufacture of white lead by the process of precipitation
by carbonic acid gas.
Various arrangements of apparatus have heretofore been employed for bringing
metallic lead in a more or less finely divided stato alternately into contact with the
solvent liquid and the atmospheric air for the purpose of oxidizing the surface of
the metallic lead and then washing off this oxide by the solvent and combining
the same therewith so as to form a salt of lead which is afterwards treated with
carbonic acid gas to produce precipitated carbonate of lead known commercially
as precipitated white lead. These arrangements have been more or less unsatis-
factory, and the object of my present invention is to produce an apparatus which
shall effect the desired result by simpler means and more perfectly and automatically
than heretofore.
For this purpose I employ a hollow drum made of wood or other material which
is not acted upon by the solvent solution employed. This hollow drum is caused
to rotate slowly on its axis by means of worm gearing or other suitablo mechanical
devices. On the internal circumference of this hollow drum and more or less
parallel with the axis thereof are secured a series of radial shelves projecting
inwards more or less towards the centre, and on the axis of the said drum are
secured other radial shelves projecting outwards towards the circumference. The
axis of the drum is made hollow and with a series of perforations which open into
the
spaces between the radial shelves on the said axis. A blast of air heated to a
suitable temperature can be admitted to the said hollow axis through a stuffing
box arrangement at one end and the spent blast of air may be allowed to escape
from the drum through another stuffing box at the other end of the axis or
otherwise.
----

page_text: Solvent liquid heated to a suitable temperature and the metallic lead in a divided
state are placed in the aforesaid drum and a slow rotary motion is imparted to the
said drum by the worm gearing or other mechanical devices, the pieces of metallic
lead are then carried up out of the solution at the lower part of the drum by the
shelves on the inner periphery of the drum until the said shelves assume such an
angle to the horizon that the pieces of lead slide off such shelves and fall into the
spaces between the shelves on the axis where they are subjected to the blast of air
issuing from the perforations in the hollow axis, until the said shelves on the axis
have turned round so far that the pieces of lead fall off from them into the solvent
liquid again.
By these means the metallic lead is submitted alternately to the action of the
heated solvent liquid and to the oxidizing effect of the heated blast of air in a
regular manner and automatically, the heated blast of air assisting to keep the
solvent solution constantly at the required temperature and facilitating the
oxidation of the metallic lead. When the solvent liquid becomes sufficiently
charged with lead salt it may be drawn off for subsequent treatment by carbonic
acid gas, and a fresh supply of solvent liquid, (and of metallic lead when necessary)
admitted to the drum. Or after the metallic lead is dissolved or the solvent is
sufficiently charged carbonic acid gas may be introduced direct into the apparatus
and the white lead thereby precipitated in a manner well understood.
It will be obvious that instead of metallic lead, previously prepared oxide of
lead may be introduced into the drum with the solvent solution for the purpose of
readily dissolving the said oxide.
The drum may be fitted with stirrers or paddles for the purpose of causing the
pieces of lead to rub one against the other so as to facilitate the removal of the
oxide from their surface.

page_text: COMPLETE SPECIFICATION.
I, ALEXANDER WILLIAM ANDERSON, of Old Kent Road, in the County of
Surrey White lead manufacturer do hereby declare the nature of the said invention
for "IMPROVED MEANS AND APPARATUS FOR FACILITATING THE DISSOLUTION OF
METALLIC LEAD OR OF OXIDE OF LEAD IN THE MANUFACTURE OF WHITE LEAD
"
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement, reference being had to the
accompanying sheet of Drawings and to the letters and figures marked thereon,
that is to say:-
My invention relates to means and apparatus for facilitating the dissolution of
metallic lead, or of oxide of lead, by the action of acetic or other suitable solvent
acid or chemical, in the manufacture of white lead by the process of precipitation
by carbonic acid gas.
Various arrangements of apparatus have heretofore been employed for bringing
metallic lead, in a more or less finely divided state, alternately into contact with
the solvent liquid and the atmospheric air for the purpose of oxidizing the surface
of the metallic lead, and then washing off this oxide by the solvent and combining
the same therewith, so as to form a salt of lead, which is afterwards treated with
carbonic acid gas to produce precipitated carbonate of lead known commercially as
precipitated white lead. These arrangements have been inore or less unsatisfactory,
and the object of my present invention is to produce an apparatus which shall
effect the desired result by simpler means, and more perfectly and automatically
than heretofore.
For this purpose I employ a hollow drum of round, square, polygonal or other
convenient shape, made of wood or other material which is not acted upon by the
solvent solution employed. This hollow drum is caused to rotate slowly on its axis
by means of worm gearing or other suitable mechanical devices. On the internal
circumference of this hollow drum, and more or less parallel with the axis thereof,
are secured a number of radial shelves projecting inwards more or less towards the
centre, and on the axis of the said drum are secured other radial shelves projecting
outwards towards the circumference. The axis of the drum is made hollow and
with a series of perforations which open into the spaces between the radial shelves
on the said axis. A blast of air heated to a suitable temperature can he admitted
to the said hollow axis through a stuffing box arrangement at one end, and the
spent blast of air may be allowed to escape from the drum through another
stuffing box at the other end of the axis, or otherwise.
Figures 1 and 2 of the Drawings show in transverse and longitudinal section,
respectively, an apparatus constructed in accordance with my invention. Similar
letters relate to like parts in each of the Figures. A is the hollow drum with the
series of radial shelves B on the internal circumference thereof. C is the hollow
axis with radial shelves D mounted thereon (Figure 1). The drum A is shewn
"

page_text: mounted upon two pairs of friction rollers E E', one pair E¹ of which is driven by
means of the gearing F but any other suitable means may be employed for driving
the said drum. G is the hot air inlet pipe provided with a stuffing box G¹ and H
and H¹ are the corresponding outlet pipe and stuffing box at the other end of the
drum A. I is a manhole through which the apparatus is charged, and J is an
outlet valve preferably provided with a strainer K.
The action of the apparatus is as follows:-
--
Solvent liquid L, heated to a suitable temperature, and the metallic lead in
a divided state, are placed in the drum A through the manhole I, and a slow rotary
motion is imparted to the said drum by the gearing F for example, the pieces of
metallic lead are thus carried up out of the solution L at the lower part of the
drum A by the shelves B until the said shelves assume such an angle to the horizon
that the pieces of lead slide off the shelves B and fall into the spaces between the
shelves D on tho hollow axis C, where they are subjected to the blast of air issuing
from the perforations M in the hollow axis C until the shelves D have turned round
so far that the pieces of lead fall off from them into the solvent liquid L again.
Hot air as before described, is introduced through the pipe G and stuffing box G¹
into the hollow axis C from whence it passes by the holes M (which are preferably
covered with gauze as shown) into the chrum A and ultimately leaves the drum by
the holes P (also covered with gauze) in the hollow axis C, and stuffing box and
pipe Hand H, its direct passage from the pipe G to the pipe H being prevented
by the partition Q in the hollow axis C. By these means the metallic lead is
submitted alternately to the action of the heated solvent liquid and to the oxidizing
effect of the heated blast of air in a regular manner and automatically, the heated
blast of air a-sisting to keep the solvent solution constantly at the required
temperature and facilitating the oxidation of the metallic lead.
When the solvent liquid L becomes sufficiently charged with lead salt, it may be
drawn off through the valve J for subsequent treatment by carbonic acid gas, the
undissolved pieces of lead being kept back by the strainer K. Additional metallic
lead may now be introduced through the manhole I and a fresh supply of solvent
liquid may be admitted to the drum preferably through the hot air pipe G which
may be provided with a junction pipe for that purpose.
Or after the metallic lead is dissolved or the solvent is sufficiently charged,
carbonic acid gas may be introduced direct into the apparatus and the white lead
thereby precipitated in a manner well understood.
3
Figure 3 shows in transverso section a modified arrangement in which the radial
shelves B are provided with lips or ledges B' in order to retain a greater quantity
of the metallic lead, the solvent liquid being allowed to run off through the holes B
in the shelves B. The hollow axis is in this case sometimes dispensed with and the
hot nir enters the drum A direct by the stuffing box G¹ and inlet pipe G and leaves 4
it by the stuffing box El¹ and pipe H.
It will be obvious that instead of metallic lead, previously prepared oxide of lead
may be introduced into the drum A with the solvent solution for the purpose of
readily dissolving the said oxide.
Having now particularly described and ascertained the nature of my said 4
invention and in what manner the same is to be performed, I declare that what
I claim is
First In the manufacture of white lead, the improved means for facilitating the
dissolution of metallic lead or of oxide of lead by bringing the metallic lead or the
oxide of lead alternately into contact with the solvent liquid and a heated blast of 5
atmospheric air in a closed hollow revolving drum or chamber containing the
solvent liquid and furnished with devices which raise and retain the metallic lead,
or the oxide of lead, out of the solvent liquid for a time while it is being subjected
to the action of the heated air, and then allow it to fall back into the solvent
-liquid, substantially as herein before described.
Second-In the manufacture of white lead the improved apparatus for facilitating
the dissolution of metallic lead or of oxide of lead, consisting of a hollow revolving
5

page_text: drum or chamber furnished with shelves or pallets which raise and retain the
metallic lead or oxide of lead out of the solvent liquid for a time while it is being
subjected to the action of heated air, and then allow it to fall back into the solvent
liquid, with means for introducing a blast of heated air into, and releasing the cooled
or spent air from, the interior of the revolving drum or chamber, and with a valve
for withdrawing the solution charged with lead from the drum or chamber,
substantially as herein before described, and illustrated in the Drawings hereto
annexed.