IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD AND IN APPARATUS THEREFOR to be as follows:
Year: 1884

page_text: I, HENRY GERARD BLYTH, of 17 Gracechurch Street, in the City of London,
Mining Engineer do hereby declare the nature of my invention for "IMPROVEMENTS
IN THE MANUFACTURE OF WHITE LEAD AND IN APPARATUS THEREFOR to be as
follows:-
"
My invention relates to improvements in the manufacture of white lead and in
apparatus therefor.
My said invention comprises a process wherein I employ oxide of lead obtained
by the cupellation of impure Spanish or other lead; or by heating impure
carbonates of lead, both mineral and artificial, tailings of lead mines, or the like, to
a temperature just sufficient to drive off the carbonic acid '(C O₂) leaving the oxide
of lead (Pb. O) uncombined. The oxide in both cases is very impure, the impurities
in the former case being metallic and in the latter case chiefly calcareous and
silicious matter. When there is much calcareous matter this crude oxide cannot
be used advantageously. The impure varieties of oxide which I employ can be
obtained at a cheaper rate than those used in the processes heretofore adopted.
My said invention also comprises apparatus which is constructed as hereinafter
described, that is to say I provide a strong cylindrical or other suitably shaped
vessel hermetically closed at its lower end. This is constructed of drain pipe of
large diameter, or of glazed earthenware manufactured for the purpose, or of
wood, or of slate or any other material of sufficient strength which will not be
injuriously affected by the materials used in the manufacture of the white lead.
This vessel should rest on a firm bed or platform of stone, wood or other material,
which bed or platform is supported by uprights or posts of timber or iron, or by
masonry. Within the said vessel and about from six to twelve inches from the
bottom thereof is a rim, which supports a perforated disc or plate hereinafter
described.
The said vessel is provided with two cocks for drawing off the liquor or solution
when desired, and is, in some instances, connected by a pipe with a similar vessel;
and an overflow pipe is also provided at a suitable height.
The aforesaid perforated disc or plate is of slightly smaller size than the inside
of the aforesaid vessel. Around this disc or plate is firmly fixed a band from about
six to eighteen inches deep and projecting above the level of the said disc or plate.
Din C27

page_text: I place on this disc or plate a layer of twigs, pebbles, coarse sand or other material
which will permit the liquor to permeate easily through it. On this material is
placed a piece of cloth or other filtering material which is stretched more or less
tightly over a rim of wood or other suitable material held together by cross-pieces
or in any other convenient manner. To the upper end of the said band are fixed
pieces of rope, cord or similar material of equal length, joined at the top, whereby
it may be raised from, or lowered upon, its support by a windlass, crab or small
crane. When it rests on the support, very little liquor can pass between the two
surfaces, but the liquor, to get to the lower end of the vessel, must pass through the
perforated disc or plate and the aforesaid filtering material.
I also provide a strong cylindrical or other suitably shaped vessel the upper part
of which is open at both ends and the lower part of which forms a receiver for the
white lead, leakage between the surfaces of these two parts being prevented by a
ring or piece of india-rubber, tarred tow, cement or other suitable material. . The
upper part is provided with two cocks and I sometimes provide it with a tube to
connect it with a similar vessel if necessary. The said vessel also has a pipe
through which the liquor overflows when it reaches a certain level. This vessel is
supported by cross-beams or in any other convenient manner. A pipe is also
provided to carry off any carbonic acid gas which may escape through the liquid.
The lower part has trunnions below its centre of gravity; and it rests on a strong
disc which can be raised by a screw or other suitable means to press it tightly
against the lower end of the upper part and thus prevent leakage. The lower part
can be removed at will by turning the screw so as to lower the said disc. The
bottom of the lower part is sometimes made so that it can be removed when the
said part is turned over on its trunnions, but is so arranged as to fit closely when
in position and prevent leakage.
In the upper part of the said vessel is supported a cylindrical or other suitably
shaped tube extending slightly above the top of the said vessel and to within about
an inch or two of the lower end of the top part thereof. The said tube has a piece
of cloth or other filtering material over its lower end, which enables the liquor in
the said vessel to slowly filter through into the said tube. About one or two feet
above the lower end of the said tube is a pipe extending from the said tube
through the wall or side of the said vessel to the exterior thereof; by this pipe the
liquor in the said tube when it reaches a certain level can flow into a tank from
which it is pumped up into the first named vessel.
In the said upper part I also provide a pipe with a rose at the lower end through
which carbonic acid gas is pumped or forced into the liquor contained in the said
vessel. This pipe is so joined to another pipe conducting the gas to it that it can
be easily removed from the liquor for a short time and have the holes freed from
any solid matter adhering to it.
The liquors drawn off from these vessels run into a tank or tanks as desired; each
vessel may have a separate tank. In the said tank or tanks the liquors may be
treated by any well known method.
My process is as follows, that is to say:-
The old and well known process of dissolving litharge or lead oxide in acetate or
sugar of lead and precipitating the oxide taken up with carbonic acid gas (CO2) is
carried out in my process in the following improved manner, viz:-The impure
litharge or oxide of lead, of the nature of that previously described, is placed on the
perforated disc or plate in the first named vessel in any quantity which may be
deemed advisable. For this purpose the said disc or plate may be raised out of
the said vessel, or it may remain resting upon its supports. The uppermost cock on
the said vessel is then closed. A solution of acetate of lead of any desired strength
(but I prefer a strong solution) is pumped into the first named vessel where it
gradually dissolves the litharge and percolates through the perforated disc or plate
into the bottom of the said vessel and flows thence through the lowermost cock
into the second named vessel in which it meets with the carbonic acid gas forced in
..through the pipe above mentioned, and white lead is thrown down or precipitated

page_text: and gradually settles to the bottom of the aforesaid lower part. Meanwhile the
liquor rises through the diaphragm or piece of filtering material of the aforesaid
cylinder or tube, and, when it reaches the level of the overflow pipe, flows into a
tank, from which it is pumped into the first named vessel to dissolve more oxide
and pass through a similar process, which it does without losing its strength to any
considerable extent. Should the pump fill the said vessel too rapidly, the liquor
flows back into the said tank by the overflow pipe or into a similar vessel to that first
named, by means of a pipe. When it is required to charge the aforesaid perforated
disc or plate with more oxide, it is either introduced while the said disc or plate
rests on its supports, or the liquor is first run off through the two cocks and the
plate or disc raised out of the vessel containing it. When the aforesaid lower part
or receptacle is nearly full of white lead, the liquor is drawn off through the two
cocks on the upper part of the vessel. The said receptacle is then lowered by
unscrewing the aforesaid screw, and, being supported by its trunnions, can be easily
turned thereon. It is then again screwed up against the lower end of the vessel.
above it, the cocks are closed and the process is carried on as before.
The white lead is washed in barrels or tanks, collected and dried, and when.
slightly pressed it becomes a powder and is fit for use. It may be ground if.
desired.
The solution of acetate or sugar of lead may be made in the first namel vessel.
if necessary or advisable, with or without the oxide being mixed with it.
The carbonic acid is generated by burning chalk or limestone in a small kiln
with a small proportion of coal, the air being drawn through it by an air-pump or
other suitable means, which also forces the gas so formed through material which
will catch or retain its solid impurities, and thence on into the second named vessel
through the pipe provided for the purpose.
The pump for raising the liquor to the first named vessel may be worked by hand
or by the same engine which pumps the air and gas. The receiver for the oxide
may also be raised and lowered by similar means.
I can employ any other well known process for producing carbonic acid.
Any deposit of white lead should be removed from time to time if it hinders the
process.
Any impurities in the oxide are either dissolved in the liquor and therefore
become concentrated, as fresh oxide is used, and can be precipitated when
sufficiently concentrated, or they remain on the said perforated dise or plate, in
which case they can be collected, dried, and smelted or treated by well known
chemical processes.
In a similar manner, the impurities in the solution can be separated and collected
by well known chemical reactions to considerable profit in many cases.
It is obvious that, by collecting the white lead in a receiver as above described,
it can be easily moved without handling.
In this process nitrate of lead may be used instead of, and in the same manner
as, the acetate or sugar of lead, with the formation of basic nitrates of lead instead
of basic acetates. In each case basic salts are afterwards reduced by carbonic
acid gas.
HASELTINE, LAKE & Co.,
For the Applicant.

page_text: 50
"
I,. HENRY GERARD BLYTH, of 17, Gracechurch Street, London, Mining Engineer,.
do hereby declare the nature of my invention for IMPROVEMENTS IN THE
MANUFACTURE OF WHITE LEAD; AND IN APPARATUS THEREFOR and in what
manner the same is to be performed, to be particularly. described and. ascertained
in and by the following statement:
My invention relates to the manufacture of white lead, and to apparatus therefor,
and is chiefly designed to provide for the production of white lead from very
impure litharge or other oxides, which can be obtained at less cost than those used
in the processes heretofore adopted.. It is also designed to facilitate the extraction.
and collection of the impurities in the oxides employed, so that the said impurities
can be utilized for various purposes.
By my invention, I am enabled to employ, in the manufacture of white lead,.
oxides such as those obtained by the cupellation of impure Spanish or other lead,
or by the heating of mineral or native carbonates of lead, as hereinafter described,
to a temperature just sufficient to drive off the carbonic acid, leaving the oxide
uncombined.. These oxides are very impure, the impurities, in the case of the
Spanish on other lead, being metallic and of considerable value, and, in the case of
the carbonates of lead, consisting chiefly of calcareous and silicious.matter. If there
is much calcareous matter combined with it,. the crude oxide cannot be used:
advantageously for my process.
In manufacturing white lead according to my invention,, I dissolve the oxide (by
means of acetate or sugar of lead),. filter the same and collect the insoluble impurities
in one vessel, and pass the liquid from this vessel. into another vessel in which
I precipitate the white lead by means of carbonic acid gas..
The lower part of the last named vessel is detachable or removable so that the
white lead precipitated therein can be conveyed or transferred to any desired place
without handling.. I prefer to construct this vessel in such a manner, that, during
the precipitation of the white lead, the liquid contained in the said vessel will pass
through suitable filtering material and can be run off and collected. in a tank or
other receptacle to be again used in my process.
I sometimes employ a series of the said vessels connected by suitable pipes and
so arranged that, while some of them are in operation, the others can be emptied.
and recharged.
My improved. apparatus is illustrated in the accompanying drawing, in which
Figure 1 is a vertical central section of my apparatus, some parts being shewn in
elevation, and
Figure 2 is a front elevation of part of the said apparatus.
Like letters indicate corresponding parts in these. Figures.
A is a vessel which is of cylindrical or other suitable form and is made of glazed
earthenware, wood, slate, or other material of sufficient strength and not liable to
be injuriously affected by the substances used in the manufacture of the white
lead, or it may be made of earthenware drain-pipe of larger diameter. This vessel.
is supported upon a firm bed or platform B of stone, wood, or other suitable
material, which bed or platform is supported by wood or iron standards or posts B¹
or by masonry or otherwise. Within the vessel A, preferably from six to twelve
inches from the bottom thereof, a rim or projection A¹ or other suitable support is
provided, upon which is placed a perforated disc or plate C hereinafter more fully
described.
The vessel A is provided with two cocks a, b for the purposes hereinafter specified,
and, in some instances, with a pipe at 6* whereby it can be connected with

page_text: a similar vessel if desired; it is, moreover, provided at a suitable height with an
overflow pipe c to be connected with a tank or other receptacle, from which the:
liquor can, if desired, be pumped back into the vessel A.
The perforated disc or plate C is slightly smaller in diameter than the interior of
the vessel A; it is bulged downward as shewn in order to strengthen it. Upon
this disc or plate are the pieces C¹ formed integrally with, or firmly secured to, the.
said disc or plate and extending upward therefrom say from six to eighteen inches.
On the said disc or plate, in the chamber formed by the pieces C₁, is placed, as,
shewn at D, a layer of twigs, pebbles, coarse sand or other material, through which
the dissolved oxide can easily permeate; and upon this layer is placed a piece of
cloth or other filtering material which is stretched more or less tightly over a rim
or frame E cf wood or other suitable material held together by cross-pieces or in
any other suitable manner. The disc or plate C is provided with chains F, F¹ or
other suitable means whereby it may be raised from, or lowered upon, its support.
by a windlass, crab, or small crane.
G is a vessel which is of cylindrical or other suitable form and is connected with
the vessel A by a pipe b. This vessel consists of an upper part g. and a lower.
part gl. The said upper part is open at both ends or at the lower end only ;.. the
lower part g' serves as a receiver for the white lead; leakage between the adjacent
flanges or surfaces of these two parts. is prevented by inserting between the same
a ring or piece of india-rubber, tarred hemp, cement or other suitable packing.
The vessel G is provided with two cocks d, e, and, in some cases, with a pipe or
tube at h to connect it with a similar vessel, if desired. The vessel G also has an
overflow pipe at i designed to be connected with a tank or other receptacle. The
upper part g, of the said vessel is supported by cross-beams H carried by brick
columns H, or it may be supported in any other convenient manner. A pipe j is
also provided to carry off, into a chimney for example, any gas which may escape
through the dissolved oxide contained in the said vessel and thus prevent any
injurious effects arising therefrom. The lower part gl has trunnions k which are.
below its centre of gravity when it is empty; these trunnions are provided with
rollers the part g¹ rests on a strong disc or plate I, which can be raised or
lowered by (but is prevented from turning with) a screw J, to raise and lower the
part g and press the same tightly against the lower end of the part g, thus
preventing leakage between the said parts. In some instances, I provide other well
known means for this purpose. The part g¹ can be removed as follows, viz:-The-
screw J is turned, by means of a hand-bar inserted in the holes I', to lower the
said disc or plate I until the rollers ¹ rest on the rails K,, whereon the part g¹ can
be readily moved in either direction. The bottom of the part gl is, in some cases,
so made that it can be removed or detached (when the said part is turned over on
its trunnions). to permit the removal of the white lead when firmly set,, but it must
fit closely against the part g when in position, in order to prevent leakage, as above.
stated.
•
+
In the upper part of the vessel G. is supported a tube L, which extends slightly
above the top of the said vessel and to within about an inch or two inches of the
lower end of the part g. A piece L¹ of cloth or other filtering material is stretched
across the lower end of this tube, so that any liquid contained in the said vessel
will slowly filter through such material into the said tube.. A pipe M extends from
the said tube L through the wall or side of the vessel G. to the exterior thereof,.
where it is provided with a cock f; the liquor in the tube L, when it reaches. the
level of the said pipe M, can flow through the said pipe into a tank N. whence it is
pumped up into the vessel A, to be again used in my process..
In the part g I also provide a pipe O having a rose O¹ at its lower end; carbonic
acid gas is pumped or forced, by any suitable means, through this pipe into the
liquor contained in the vessel G. The pipe O is so joined to another pipe
conducting the gas thereto that it can be easily removed from the liquor for a short
time in order to free the holes in the rose O¹ from any solid matter adhering
.thereto.

page_text: •
In the manufacture of white lead according to my invention, I employ the old
and well known process of dissolving litharge or lead oxide in acetate or sugar of
lead and precipitating the oxide taken up with carbonic acid gas, but I carry on
this process, by means of the apparatus shewn in the drawing or substantially
similar apparatus, in the following improved manner, that is to say -A suitable
quantity of the litharge or oxide of lead is placed on the perforated disc or plate C
in the vessel A, as shewn at P. The cock a on the said vessel being closed and the
cock b open, a solution of acetate or sugar of lead of any desired strength (but
preferably a strong solution) is pumped or otherwise introduced into the vessel A,
where it gradually dissolves the litharge or crude oxide, the product percolates
through the perforated disc or plate C and the filtering material thereon into the
lower part of the said vessel, and flows thence through the cock b and the tube or
pipe 6 into the vessel G ; in this vessel it meets with the carbonic acid gas forced in
through the pipe O, and white lead is thrown down or precipitated and gradually
settles to the bottom of the part gl. During this precipitation, the liquid (acetate
or sugar of lead) in the vessel G rises through the diaphragm or piece L' of filtering
material into the tube Land, when it reaches the level of the pipe M, flows into
the tank N, from which it is, if desired, pumped into the vessel A wherein it can
be used to dissolve more oxide, the solution of the oxide by the said liquid not
materially affecting the strength of the latter. It will thus be seen that, by my
apparatus, while the precipitation of the white lead is taking place, the liquid,
which has been employed for dissolving one quantity of the material used, is
passed through filtering material and can be run off and again used. If too much
of the liquid is pumped into the vessel A it. will flow back into the said tank. by
the overflow pipe c; or it may be made to flow into a vessel similar to the vessel A
by means of the pipe b*.
To charge the perforated disc or plate C with oxide, the latter is either introduced
while the said disc or plate rests on its support, or the liquid is first run off and the
said plate or disc is raised out of the vessel A.
The liquor drawn off from the vessels A and G may be either run into the same
tank or tanks, or each of the said vessels may have a separate tank for this
purpose. In the said tank or tanks, the liquor is heated in any convenient or well
known manner, if it is found desirable to employ the same at an elevated
temperature.
Moreover, in some instances, the liquor drawn from the cock f is collected in a
different tank from that which receives the liquor from the cocks d and e; as that
from fis more pure than that from & and e.
When the receptacle g¹ is nearly full of white lead, the liquor is drawn off from
the vessel G through the cocks d and e. The said receptacle is then lowered by
the screw J, and, being supported by its trunnions & and rollers k¹, on the rails K
(which are preferably slightly inclined) can be easily pushed or moved to any
desired place thereon, and then turned over to empty it. After the said receptacle
is emptied, it is again screwed up against the lower end of the part g, the cocks
are closed, and the process is carried on as before.
In manufacturing white lead from mineral or native carbonates of lead.according
to my invention, the said carbonates are cautiously heated to a temperature just
sufficient to drive off the carbonic acid or carbon dioxide (C O₂) leaving the lead
oxide (Pb O) uncombined, and in a condition to be dissolved by acetate or sugar
of lead. The oxide is then dissolved and the white lead precipitated as above
described.
The white lead obtained as above described is washed in barrels or tanks,
collected and dried, and is then pressed and, if necessary, ground to form a powder;
it is then fit for use.
The solution of acetate or sugar of lead may be made in the vessel A if necessary
or advisable, the oxide being mixed or unmixed with it, as desired.
Any impurities in the oxide employed are either dissolved in the liquor, and
therefore become concentrated when fresh oxide is used, and can be precipitated

page_text: when sufficiently concentrated; or they remain on the perforated disc or plate C,
in which case they can be collected, washed, dried and smelted or treated by well
known chemical processes, to be used for any purpose for which they may be
applicable.
In a similar manner, the impurities in the solution can be separated and
collected by well known chemical reactions, with considerable advantage in many
cases.
It is obvious that, by collecting the white lead in a receiver as above described,
it can be easily moved or transferred to any desired place without handling.
I might use in this process nitrate of lead instead of, and in the same manner as,
the acetate or sugar of lead; but I prefer to use the acetate.
I am aware that white lead has been heretofore made by dissolving litharge or
lead oxide in acetate or sugar of lead and then precipitating the white lead by
means of carbonic acid gas. Therefore I do not make any claim to such process
except when carried out in the improved manner above described and by means of
apparatus operating on the principles above set forth.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is:-
First. The improved method or process which consists in dissolving and filtering
the litharge or crude oxide, collecting the impurities, and precipitating the white
lead as above set forth, by means of the apparatus shewn in the accompanying
drawing or substantially similar apparatus.
Second. The above described method or process of manufacturing white lead
from mineral or native carbonates of lead by first heating the said carbonates to
drive off the carbonic acid, and then dissolving the oxide and precipitating the
white lead as above specified.
Third. The peculiar construction of the said apparatus whereby, during the
precipitation of the white lead, the liquor above the same is filtered and can be run
off and collected to be again used, as above set forth.
Fourth. The construction of the vessel, for the precipitation of the white lead,
in two parts substantially as described, so that the lower part will serve as the
receiver for the white lead.
Fifth. The improved apparatus consisting of the vessels A, G, and their adjuncts
constructed and combined substantially as described with reference to the
accompanying drawing for the purpose specified.
HASELTINE, LAKE & Co.,
For the Applicant.