Improvements in the Manufacture of Carbonate or Sulphate of Lead.
Year: 1897

page_text: Date of Application, 21st Dec., 1897-Accepted, 12th Feb., 1898
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Carbonate or Sulphate of Lead.
We, ARTHUR HENRY EYLES, Chemist, of 103, Madison Street, Mount Vernon,
HENRY STAPLES RAPELYE, Architect, of 103, S. 6th Avenue, Mount Vernon, and
ADDISON APPLEGATE, Builder, of 316, Franklin Avenue, Mount Vernon, West-
chester County, State of New York, United States of America, 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:-
Our invention relates to a process for making carbonate or sulphate of lead and
may be practised as follows:-Pig lead or pure metallic lead is melted in a furnace
to a state of fluidity nearly approaching the point of volatilization and is then run
through a nozzle on to a stream of steam at high pressure or a stream of compressed
air at a very high temperature and pressure. The result will be that the molten
lead will be divided into a state of minute division. The steam or air jet is directed
through a tunnel into a chamber in which the air is artificially heated and the
bottom of which is covered with water preferably containing a small percentage of
acid, say nitric acid or acetic acid. The particles of lead carried along by the blast
rapidly oxidize and fall into the water in several stages of oxidization as the con-
dition of the air or the temperature of the lead may produce, so that the water will
be found to contain small particles of aggregated lead which are minute particles
of lead which after division in the steam jet, mass together again by impact and
which by reason of such aggregation, have not been oxidized, particles which have
taken only a small amount of oxygen and are in the form of a gray sub-oxide,
particles which have taken the full proportion of oxygen and appear in the form of
protoxide and occasional particles which have by reason of a high temperature been
converted into a pink or peroxide. The acid in the water stimulates oxydation
and breaks up the aggregation of lead which is converted into the condition of
hydrated oxide. This action may be accelerated by agitating the water, as by means
of rakes moved backwards and forwards through the lead on the bottom of the
chamber. In order to bring all these varying oxides comprising the mixture into
the condition of protoxide from which basic carbonate of lead can be made, the lead
oxides with five times their volume of hot water are placed in a revolving tub, into
which a volume of hot air is passed. The elements constituting the material in
the tub are still in a nascent state, that is to say, the oxides have not been fixed,
as they have been under water since their formation, and therefore under the
influence of the heat the oxides in the revolving tub readily change into protoxide,
the metallic lead and the sub-oxides in the tub taking on more oxygen and the
peroxide yielding up its superabundant oxygen. Thus the mass is made of homo-
geneous protoxide, in which condition alone it is capable of being converted into
carbonate of lead.
For the purpose of disposing of the free acid resulting from the acidulated water
in the chamber previously referred to, a sufficient quantity of ammonia or some
other caustic alkali is introduced which in the process of neutralization has been
found of additional value in bringing about the protoxidization of the mass.
protoxide is then taken and placed in a tub, such for instance as that forming the
The

page_text: subject matter of previous Letters Patent of A. H. Eyles, dated August 17th 18977
No. 19030, the said tub being of special construction, as hereinafter set forth.
When the protoxide in admixture with water has been placed in the tub, the tub
is revolved and the protoxide carbonized therein by the introduction or carbonic
acid gas which is uniformly dispersed throughout the mass of protoxide and as is
well understood, will carbonize the mass producing a hydrated carbonate of lead.
An apparatus for carrying out our invention is illustrated in the accompanying
drawing, and will be understood by reference thereto. In this drawing--
Figure 1 is a side elevation of the apparatus for melting and oxidizing the lead.
Figure 2 is a sectional detail elevation of the tub for carbonating the lead after
the said lead has been oxidized and the oxides equalized, as described.
Figure 3 is a detail side elevation of a cleat employed in the tub, shown in
Figure 2, and
Figure 4 is a detail perspective view thereof.
In the drawing, A represents the furnace for melting the lead, which is provided
with a proper crucible B. C is the air compressor from which a pipe I leads into
the casing of the lead furnace, where the air is heated to a very high temperature,
and is led from the said casing by means of a pipe E provided with a nozzle F
discharging into a tunnel G, which leads to a chamber H whose contained air is
heated by extraneous means not shown. At the bottom of the chamber is a layer
of water I about six or eight inches deep. Rakes I may be immersed in the sail
water for the purpose of stirring the lead oxides which drop to the bottom of the
chamber. Located above the steam jet is a pan or sieve J to which molten lead is
brought from the crucible by means of the pipe K. In order to prevent the lead
from cooling in its passage from the crucible to the jet, the pipe K is heated by the
heater K from which source the sieve J is also heated. This molten lead, as before
explained, is heated to a very high temperature, being in a state of fluidity nearly
approaching the point of volatilization. The lead drops from the sieve in drops
and is projected by the hot air or steam jet issuing from the nozzle through the
tunnel G and into the chamber H, where it falls into the water I which, as before
stated, is by preference slightly acidulated. The oxides are thrown into the
acidulated water and kept under the said water in order to prevent them from
becoming fixed before further treatment. Inasmuch as the formation of hydrated
oxide will still go on from such metallic lead as may not have been oxidized by
the blast the water is slightly acidulated to assist in the corrosion of large particles
of lead which may have been carried along and to promote oxidation thereof and it
has also been found that the acid is effective to partially dissolve any peroxide
which may have been formed. The slight proportion of acid used should not appear
in the final product and may be gotten out of the product at any stage in the
manipulation thereof either by being washed out with water or neutralized with a
It will be
suitable alkali, as will be well understood by those skilled in the art.
understood that the air from the air compressor is blown through the chamber
below the crucible and is heated to a very high temperature thereby. The steam,
in case steam is used instead of air, is brought to the jet by means of the pipe Fi
from any suitable source of steam supply. From the chamber H the lead oxides
and water may be removed to an oxidizing barrel or tub, which may be of the
form shown in Figure 2 where the oxides are treated with hot air. This treatment
of the mixed oxides with hot air is for the purpose of bringing the said mixed
oxides to a uniform state of protoxide and is effected as follows. The mixed oxides
and water are in the revolving tub subjected to agitation and at the same time the
heated air is brought in contact with the agitated mass. All these elements acting
upon the mass of oxides have the effect of converting the said oxides into protoxide,
that is to say, the lower oxides take up oxygen and the higher oxides yield oxygen,
so that the whole mass is converted into a uniform state of protoxide. The chief
novelty in our process lies in this step, that is to say, converting the lower oxides
and the higher oxides in the mass into protoxide so as to prepare the mass for
carbonization. When the oxides have been treated with heat and air and thereby

page_text: brought uniformly to a protoxide they are then removed from the oxidizing barrel
or tub and placed in a similar barrel or tub which, instead of being supplied with
oxygen, is supplied with carbonic acid gas. This tub is, as explained, similar in
construction to the tub or barrel shown in Figure 2 and the carbonic acid gas is
uniformly disbursed therethrough and reduces the protoxide to carbonate of lead.
The barrel shown in Figure 2 may consist of an outer casing a into which an
entry pipe b leads. This entry pipe b is provided with apertures c which deliver the
gas to the barrel over the surface of a convex bell d, which bell serves to spread
and dissipate the gas and prevent the same from blowing in a small stream through
the barrel, which spreading of the gas will bring the same into contact with the
sides of the barrel. A similar belle is located at the opposite end of the barrel
and is affixed to an exit pipe f which is provided with apertures y for allowing
the gas to escape from the barrel into the exit tube f, the convex bell e serving the
same purpose as the convex bell d. Mounted upon the walls of the barrel are
pallets or cleats h, shown in detail in Figures 3 and 4. These pallets are of a
peculiar construction in order to overcome a difficulty existent in oxidizing tubs
or barrels of this character. In the ordinary oxidizing revolving tub, the masses
of oxide being glutinous, were carried around by the pallets without dropping
through the current of gas passing through the barrel, or if they did drop, did so
in a mass, and therefore failed to properly oxidize. To overcome this difficulty we
have provided the cleats with pegs i projecting from their upper surfaces and
their edges, which pegs prevent the glutinous mass from falling from the cleat in
a mass and divide the same, so that as it falls through the body of the barrel
it will be properly divided so as to be sufficiently oxidized.
We have not as yet been able to determine with absolute accuracy the re-actions
at any given moment or the chemical formulae of the niass during manufacture.
When the lead has been blown into the acidulated water the aggregated mass at
the bottom of the water has a gray or grayish black colour in which a greenish
tinge appears and likewise a pink colour frequently appears.
Now in accounting
for these various colours it is not quite possible to state the exact chemical con-
dition of the mass. For instance, it is perfectly clear that the gray colour is due
to the preponderance of the gray sub-oxide of lead Pb, and metallic lead which
is bluish gray.
The greenish tinge may represent a formation approximating the
formula Pb,O, or it may arise from the mechanical admixture of Pb,O which is
the gray sub-oxide and 1'b0 the protoxide which, as is well known, is yellow. It is
undoubtedly true that protoxide is formed, and frequently, when atmospheric and
other conditions are favorable, the peroxide PbO, which is of a pink colour is
formed, but usually under ordinary conditions, in quite a limited amount.
determining the degree of oxidization it is our practice to be governed wholly by
the colour of the mass, so that when the mass takes on a yellow colour we know that
the oxidization is proceeding far enough to be called a uniform protoxide, although
it is quite possible that traces of other oxides may be found in the mass.
In
Instead of carbonizing the protoxide in order to produce carbonate of lead we
may sulphurize the same and reduce them to sulphate of lead which is likewise
useful as a pigment. This may be done by treating the protoxide with sulphuric
acid in the tub or barrel containing the protoxide which will thereupon be con-
verted into sulphate of lead. Wherever in the specification and claims we refer to
carbonating lead we would have it understood that we likewise mean to thereby
include the manufacture of sulphate of lead from the protoxide.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is:
1. The herein described process of manufacturing carbonate of lead, the same
consisting in oxidizing the lead by feeding the same in a molten state closely
approaching volatilization into a stream of fluid at high temperature and pressure
and carrying the same along in the stream, whereby the lead is oxidized to different

page_text: degrees of oxidization, dropping the said mixture of oxides into a fluid whereby
the said oxides will not become fixed and subsequently converting the said mixture
of oxides into a uniform state of protoxide and thereupon carbonating the protoxido
so produced.
2. The herein described process of manufacturing protoxide of lead, which con-
sists in heating the lead to a molten condition closely approaching volatilization,
feeding the said lead while in such highly heated condition into a stream of fluid
at high temperature and pressure and carrying the same along in the stream,
thereby oxidizing the lead to different degrees of oxidation, dropping the said
mixture of oxides into a fluid which will prevent said oxides from becoming fixed
and thereupon heating the said mixture of oxides and simultaneously agitating the
same to convert the said mixture of oxides into a uniform protoxide of lead.
Dated this 21st day of December 1897.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.
A. M. & WM. CLARK,
Chartered Patent Agents, 53, Chancery Lane, London.