Year: 1885

page_text: We, JAMES HAYLOR of Chichester Road, Kilburn in the County of Middlesex,
Rate Collector, HENRY SPENCER READ of St Albans in the County of Herts,
Engineer and HENRY GEORGE PERCIVAL of Libra Road, Plaistow in the County
of Essex, Metal Founder, do hereby declare the nature of this invention to be as
follows:-
The ordinary process for manufacturing white lead consists in casting metallic
lead in pieces presenting large surface, usually in form of gratings; exposing these
in a chamber supplied with a mixture of heated gases and vapours, air, carbonic
acid and acetic acid until a crust of carbonate is formed on the lead, then removing
the crust, and grinding, washing and drying it. Our invention relates to apparatus
for effectually and rapidly carrying on the successive steps of the process, and
particularly for avoiding as much as possible manipulation of the material or
exposure of workmen to the injurious effects which it is apt to produce. For this
purpose, we form the floor of the carbonating chamber as a hot plate heated by
steam or hot water pipes or coils below it, and over this floor we spread a layer of
liquid acetic acid. In the middle or other suitable part of the chamber we place
on the floor a box open underneath so that its edges are immersed in the acetic
acid, and into this box above the level of the acid we introduce by pipes from
without the necessary supply of air and carbonic acid. The sides of the box
being perforated with numerous small holes the gases mingled with acetic acid
vapour issue from these holes in a diffused condition and distribute themselves
over the chamber in which the pieces of lead are arranged on suitable shelves or
frames. As the mingled gases and vapour are not entirely absorbed in the one
chamber, we prefer to lead them as they are discharged from it into a second
chamber to act on other pieces of lead therein. The mixing box above described
being portable can be removed, leaving the floor of the chamber clear for workmen
employed in stacking the fresh lead or removing the carbonated lead. The lead
gratings encrusted with carbonate are moved by lifts, travelling bands or otherwise,
according to the arrangements of the building, to the mill in which the carbonate
is separated from the metallic lead and prepared for the market. The first part of
the mill consists of several sets of squeezing rollers through which the encrusted
pieces are passed. The squeezing and bending to which they are thus subjected
°

page_text: cause the crust of carbonate to flake off. In order to avoid the spread of fine dust
of carbonate, we prefer to provide over the squeezing rollers nozzles distributing
a fine spray of water. While the metallic lead is conveyed by a travelling band
or otherwise to the melting pots to be again cast into gratings, the flakes and.
particles separated by the squeezing rollers pass continuously through crushing
and grinding rollers and through a washing vessel in which they are agitated with
water and caused to advance by means of a revolving agitator having helical or
inclined arms, The mixture of white lead and water passes from the washing
vessel into a settling tank, where the white lead subsides, and the water is
decanted from above it leaving the moist white lead below. This is in its turn
passed through mill stones by which it is converted into a fine paste, and this
paste is conducted by worms along channels heated by steam by which it is dried.
The dried carbonate may be at once packed for transport, or if it is to be mixed
with oil, this is done in the usual way by rolling and pugging.
ABEL & IMRAY,
Agents for the Applicant.
P
We, JAMES HAYLOR of Chichester Road, Kilburn in the County of Middlesex,
Rate Collector, HENRY SPENCER READ of St Albans in the County of Herts,
Engineer, and HENRY GEORGE PERCIVAL of Libra Road, Plaistow in the County of
Essex, Metal Founder, 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:-
The ordinary process for manufacturing white lead consists in casting metallic
lead in pieces presenting large surface, usually in form of gratings; exposing these
in a chamber supplied with a mixture of heated gases and vapours, air, carbonic
acid and acetic acid until a crust of carbonate is formed on the lead, then removing
the crust, and grinding, washing and drying it. Our invention relates to apparatus
for effectually and rapidly carrying on the successive steps of the process, and
particularly for avoiding as much as possible manipulation of the material or
exposure of workmen to the injurious effects which it is apt to produce. For this
purpose, we form the floor of the carbonating chamber as a hot plate heated by
steam or hot water pipes or coils below it, and over this floor we spread a layer of
liquid acetic acid.. In the middle or other suitable part of the chamber, we place
on the floor a box open underneath so that its edges are immersed in the acetib.

page_text: acid, and into this box, above the level of the acid, we introduce by pipes from
without the necessary supply of air and carbonic acid. The sides of the box being
perforated with numerous small holes, the gases mingled with acetic acid vapour
issue from these holes in a diffused condition and distribute themselves over the
chamber in which the pieces of lead are arranged on suitable shelves or frames:
As the mingled gases and vapour are not entirely absorbed in the one chamber, we
prefer to lead them as they are discharged from it into a second chamber to act on
other pieces of lead therein. The mixing box above described being portable can
be removed, leaving the floor of the chamber clear for workmen employed in
stacking the fresh lead or removing the carbonated lead. The lead gratings
encrusted with carbonate are moved by lifts, travelling bands or otherwise;
according to the arrangements of the building, to the mill in which the carbonate
is separated from the metallic lead and prepared for the market. The first part of
the mill consists of several sets of squeezing rollers through which the encrusted
pieces are passed. The squeezing and bending to which they are thus subjected
cause the crust of carbonate to flake off. In order to avoid the spread of fine dust
of carbonate, we prefer to provide over the squeezing rollers nozzles distributing
a fine spray of water. While the metallic lead is conveyed by a travelling band
or otherwise to the melting pots to be again cast into gratings, the flakes and
particles separated by the squeezing rollers pass continuously through crushing
and grinding rollers and through a washing vessel in which they are agitated with
water and caused to advance by means of a revolving agitator having helical or
inclined arms. The mixture of white lead and water passes from the washing
vessel into a settling tank, where the white lead subsides, and the water is
decanted from above it leaving the moist white lead below. This is in its turn
passed through mill stones by which it is converted into a fine paste, and this
paste is conducted by worms along channels heated by steam by which it is dried.
The dried carbonate may be at once packed for transport or if it is to be mixed
with oil; this is done in the usual way by rolling and pugging.
Fig. 1 of the accompanying drawings is a transverse section of the lower part of
a carbonating chamber arranged according to our invention, and Fig. 2 is a plan of
the floor. The floor is made with a basin like depression in the middle to hold
a layer of acetic acid which may occupy only that portion of the floor, or, when
a larger surface of acid is required it may not only fill the basin but also extend
over the whole floor. Under the floor are channels A A for steam to give heat,
and other channels B B for admitting carbonic acid and air, the mouths b b of
these projecting above the level of the acetic acid on the floor. Over these
mouths bb of the channels B B are placed the removeable distributing boxes C C
which are open at the bottom and have perforations through the upper parts of
their sides and ends. The carbonic acid and air issuing from the mouths b are
prevented from escaping under the lower edges of the boxes C which are sealed by
the liquid, but escape in separate streams by the perforations of the boxes and
mingle with the vapour rising from the acetic acid. Fig. 3 is a vertical section
drawn in diagrammatic form so as to shew the relative situation and action of
the machines for treating the lead and the carbonate with which it becomes
encrusted in the carbonating chamber. The encrusted pieces are conveyed by
a travelling band D to a set of rollers E, and they drop from these down a grating
shoot to another set of rollers F. By the squeezing and bending to which they
are thus subjected, most of the crust is caused to flake off, the metallic lead passing
away by a band G to be melted over again into fresh pieces suitable for being
carbonated; obviously, instead of two pairs of rolls E and F, a greater number
may be used and these may be arranged in tiers with guides leading the pieces
of crushed lead from each pair to the next in order. The crust scaled off descends
a hopper H to a roller mill K by which it is pulverised, and the pulverised
material descends from the mill K into the washing vessel L in which it is agitated
with water by the arms of a revolving agitator. To prevent dissipation of the
dust a spray of water is kept playing on the rollers E and F and the bands D

page_text: and G and this water accompanies the carbonate through the mill K and into the
washing vessel L. After sufficient washing a sluice is opened allowing the
partially fluid mixture of water and white lead to descend into the settling tank M
in the bottom of which there is a worm N. After settling, a sluice m is opened
and the worm N is caused to revolve transferring the settled pasty white lead to
an elevator O by which it is, raised to levigating mill P. From the mill P the
levigated paste descends to a trough Q heated by steam and is caused by a
worm R to travel along it becoming dried on its way until it issues as a dry
powder by the shoot S. Obviously, instead of a single long drying trough Q,
there may be a number of these superposed, the white lead being conducted from
each to and along the next in order below it.
t
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed we declare that what
we claim in respect of apparatus for the manufacture of white lead is :-
1. The arrangement of heated floor for the carbonating chamber with remove-
able distributing boxes, substantially as herein described with reference to Figs. 1
and 2.
2. The arrangement of machines for treating carbonated lead to operate in
sequence, first by rollers to bend and squeeze and so cause the carbonated crust
to scale off, secondly by a roller mill to pulverize the carbonate, thirdly by a
washing machine to separate soluble impurities, fourthly by a settling tank to
effect subsidence of the white lead, fifthly by millstones to levigate the white lead
paste, and sixthly by a drying apparatus to dry the white lead, substantially as
described with reference to Fig. 3.
11
1000