IMPROVEMENTS IN THE MANUFACTURE OF PHOSPHORUS
Year: 1879

page_text: LETTERS PATENT to John Clayton Mewburn, of 169, Fleet Street, in the
City of London, Patent Agent and Consulting Engineer, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF PHOSPHORUS." A communication
from abroad by Jean Pierre Serve, of Givors, France.
Sealed the 24th June 1879, and dated the 4th January 1879.
PROVISIONAL SPECIFICATION left by the said John Clayton Mewburn at
the Office of the Commissioners of Patents on the 4th January 1879.
JOHN CLAYTON MEWBURN, of 169, Fleet Street, in the City of London, Patent
Agent and Consulting Engineer. "IMPROVEMENTS IN THE MANUFACTURE OF
PHOSPHORUS." [A communication from abroad by Jean Pierre Serve, of Givors,
France.]
This Invention has reference to the manufacture of phosphorus by the dry way
by means of phosphates generally but particularly earthy phosphates of lime.
In this manufacture I employ the well known reaction of silica on phosphates,
but I prepare the materials in a special manner which much facilitates the reaction
and the separation of the phosphorus.
It is this mode of production which constitutes the essential feature of the
present Invention.
It comprises three principai operations-First, the reduction of the phosphates
to fine powder; secondly, the intimate admixture of these phosphates with silica
and charcoal likewise reduced to powder; and, thirdly, the agglomeration of this
mixture into the form of blocks or bricks.
I proceed to describe the manner in which the Invention is carried into effect.
can employ any phosphates of lime; the richer they are in tribasic phosphates
of lime the greater is the product; but these phosphates are generally all good,
that is to say, the operation can be effected with all whether they be phosphates of
lime, bones, fossil phosphates of lime, coprolites, phosphorites, apatites, or others,
and even phosphates of baryta, magnesin, iron, and others.
If fossil or mineral phosphates be used it is well to select those which are as free
as possible from lime, alumina, or magnesia uncombined with the phosphorus.
The phosphate is pulverized very finely, the finer it is the better, and silica also

page_text: very finely pulverized is added to it. This silica can be obtained from any con-
venient source, and like the phosphate the finer it is the better. Clay might be
used if very silicious; it would be even better, because clays being nearly all of
multiple silicates therefore the silicate becomes better formed, and the dross or
refuse is more fluid and flows more readily. The quantity of silica is not fixed, but
the operation generally works well if a weight of silica equal to the weight of the
tribasic phosphate which the phosphate contains be used; the proportion will vary
according to the purity of the materials employed.
To this mixture is added solid charcoal, also pulverized, in the proportion of the
equivalent of the phosphoric acid to be reduced plus a little excess, that is to say,
to enable the oxygen which will be displaced from the phosphoric acid to combine
with the carbon and form oxide of carbon or at least carbonic acid. The materials
are mixed and worked up with a sufficient quantity of water, and then made into
blocks or bricks of any desired form, hollow or not; the blocks are then dried and
may be burnt and cooled in a close vessel if they are not employed hot, so as to
prevent the carbon being burnt before the chemical reaction which decomposes the
phosphate can take place.
These blocks are introduced either on to the bed of a furnace, reverberatory or
not, or into a cupola furnace, or into a blast furnace like those employed in
metallurgy. The charging of the blast furnace is effected, as in metallurgy, by
having when required a double shutter or closing arrangement at the mouth to
prevent loss, and the furnace works in the same manner. The only difference is
that the products to be collected are in the state of vapours, gases, or small crystals
very minute. There are numerous ways in which they can be collected. That
which is preferred consists in directing the products of combustion and the phos-
phorus in the state of vapor into a large descending column cooled by a shower of
water, which condenses the phosphorus and causes it to fall into a trough of water;
the gases thus deprived of phosphorus and composed chiefly of oxide of carbon may
be utilized for producing heat.
As it is desirable that the blocks should crumble as little as possible they may
be made more solid by mixing with them a salt or acid. Soluble glass (silicate of
soda and of potassa) gives great solidity to the blocks, and adds very divided silica
which facilitates the action upon the phosphate. Solidity may also be given to the
blocks by adding to them pitches or tar; the blocks are then carbonized or not,
and this is a mode of introducing carbon into the blocks, or a suitable mucilage or
sugary materials may be employed.
The introduction of carbon into the blocks is not absolutely indispensable; but
then it is necessary for the blast furnace to work so as to give oxide of carbon as
pure as possible in order that it may be sufficiently a reducer.
When certain fossil phosphates are used, which nature has impregnated with a
sufficient quantity of silica, the addition of silica in forming the blocks might be
dispensed with.
If the blast or other furnace employed produces much phosphoric acid and
metalloidal phosphorus is desired, this acid is treated by the known means in retorts
in order to reduce it.
In like manner, if the product is much in the state of phosphorus, and phosphoric
acid is desired, the phosphorus is treated by the known means to transform it into
phosphoric acid. However, when the process in the furnace gives much phosphorus,
and phosphoric acid is desired, it is easy to obtain it at once by introducing air into
the pipes which lead to the condensing apparatus, but then the oxide of carbon
cannot be utilized.
If instead of a blast furnace a furnace with a bed or sole be employed there
should be very reducing flames in the furnace, and in order to collect the gases or
vapors the combustion for heating the furnace should be carried on under pressure,
and an energetic draft should be established beyond the condensing apparatus, so
that the gases and vapors produced in the furnace may have a discharge

page_text: sufficient, notwithstanding the condensing apparatus, for the furnace to be heated
sufficiently.
If furnaces with grates be used they should be worked with a forced draft; if
the furnace is a gas furnace like a Siemens furnace it should have a forced draft
under the grates of the gas generatora, and the air for combustion in the furnace
should likewise be forced. The mode of heating with coal or fuel in the state of
dust may also be utilized with advantage.
From the foregoing explanation it will be readily seen that a great number of
arrangements for reducing and condensing may be adopted, but the essential point
is a good preparation of the blocks if silicious phosphates be not used. The
mixtures should be such as to give very fusible multiple silicates.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Clayton Mewburn in the Great Seal Patent Office on the 25th
June 1879.
JOHN CLAYTON MEWBURN, of 169, Fleet Street, in the City of London, Patent
Agent and Consulting Engineer. "IMPROVEMENTS IN THE MANUFACTURE OF
PHOSPHORUS." (A communication from abroad by Jean Pierre Serve, of Givors,
France.)
This Iuvention of improvements in the manufacture of phosphorus is based on
the reaction known to chemists of silica on earthy phosphates. When an earthy
phosphate of lime, baryta, strontian, or alumina is submitted to a high temperature
in presence of silica, the acid of the latter displaces the phosphoric acid and
liberates it. If on the other hand this phosphoric acid is in the presence of a
reducing carburetted body, charcoal, oxide of carbon, carburetted hydrogen, it is
reduced and is transformed into phosphorus.
When this reaction is utilized by beating in a closed vessel a suitable mixture of
phosphate, silica, or a silicious body, and a carburetted body as the heat necessary
for displacing the phosphoric acid and for the combination of the silica with the
earthy bases is very great, the consumption of fuel is considerable, the wear of the
retorts is very rapid, and the decomposition of the phosphate incomplete.
These objections may be overcome by producing the reaction not in a retort or
in a distillatory apparatus but in a blast furnace, similar to those which are used
in smelting iron. I proceed in the following manner :-
An ordinary blast furnace from 25 to 40 feet in height, according to the pro-
duction desired to be obtained, and provided with a double closing arrangement
at the upper part to prevent the escape of gns, is charged with alternate layers of
coke, or charcoal, or anthracite coal, or a mixture of these combustibles and
mixtures of natural earthy phosphates, calcined bones, coprolites, apatites, &c., and
crushed quartz or silicious matters in which the silica is not saturated by bases.
These mixtures are prepared in the form of blocks or bricks. When the materials
are opposite the tuyeres a blast is given, the silica in contact with the phosphate
takes the place of the phosphoric acid, producing an alumino-calcareous slag similar
to that of blast furnaces. The phosphoric acid drawn upwards meets the incan-
descent fuel, on contact with which it is reduced and transformed into phosphorus
which is eminently volatile. A gas outlet. situated at about two thirds of the
height of the apparatus leads the products of combustion and the phosphorus in a
state of vapor into a large descending column cooled by a shower of cold water,
which condenses the phosphorus and causes it to fall into a trough of water which
is kept cold; the gases thus deprived of phosphorus and composed chiefly of oxide
of carbon may be utilized for producing heat.
It is important that when the natural phosphates do not contain sufficient silica,
intimate mixtures of phosphate and silica or a silicious body should be made by
pulverizing the materials and forming them into blocks or bricks, the combining
or agglomerating material being a carburetted body, such as coal tar, pitch,
oils, &c.; these bricks being baked or burnt out of contact with air yield
compounds the reduction and fusion of which are very easy.
If a portion of the phosphoric acid be drawn away without being reduced it is
found in solution in the cleansing water, and can be precipitated in the state of
soluble phosphate by lime.
It is scarcely necessary to remark that the transformation of the phosphorus into
phosphoric acid suitable for agriculture can be effected almost without cost by the
simple combustion of the phosphorus in chambers.
The manufacture of phosphorus in blast furnaces can be effected under good
conditions only when the materials are previously made into bricks; it is only

page_text: under these conditions that sufficiently fusible materials can be obtained, bringing
together at the proper time all the elements of chemical reaction.
If nodules of phosphate of lime and nodules of silica were put into a blast furnace
bodies completely refractory would be brought together which would combine with
difficulty opposite the tuyeres, that is to say, at the place where the temperature is
the highest; but the atmosphere at this part is not a reducer, consequently not the
smallest quantity of phosphorus would be obtained whatever might be the pro-
portions of materials employed, and all would go into the slag.
The previous manufacture into bricks of the materials from which the phosphorus
is to be made in a blast furnace is therefore indispensable; it is a new condition,
which if it has been already employed in different metallurgical operations has not
hitherto been applied to the manufacture of phosphorus in a blast furnace.
The effect of this making into bricks is that all the elements which should
produce the chemical operation by their reciprocal reactions are brought together
or into each other's presence. The inolecules of silica or silicic acid are in imme-
diate contact with the molecules of phosphate to be decomposed, and which should
free the phosphoric acid and form silicate; the phosphoric acid in a nascent state
meets the charcoal which reduces it, and the phosphorus is disengaged in the state
of vapor.
There are thus two successive decompositions which are effected almost at the
same time; this reaction has nothing in common with the reduction of a metallic
oxide by carbon, an operation in which there is solely a reaction of the reducing
carbon upon the oxide and a liberation of the metal.
The phosphates and the silica which should be used in the reaction are finely
pulverized, then moistened, worked up and moulded; ground solid carbon can be
added to this paste.
The dried bricks are then ready to he put into the furnace.
In order to effect the manufacture of the phosphorus in a blast furnace I arrange
the latter with certain peculiarities of construction, especially in regard to its
combination with the apparatus for condensing the vapors of phosphorus which are
disengaged from the upper part.
The blast furnace is constructed as usual (as seen in the annexed Drawing) with
a crucible C, to receive the slag and holes O for the tuyeres or blast pipes. At the
upper part is a cylinder A extending downwards into the furnace, and which forms
an annular space in which the vapors of phosphorus collect; these vapors escape by
the pipe B and are condensed in the column G.
The apparatus for charging the blast furnace consists of a hopper T with a double
cone; the two cones E and do not work simultaneously but one after the other,
so that the vapors of phosphorus cannot escape. The rod t of the lower cone E
passes through the cone F; it is fastened to a cord or chain c which passes over a
pulley p; the cone F is likewise fastened to the cords or chains cl which pass over
the pulleys pl; all the cords or chains carry weights X, which keep the cones
constantly upon their seats.
The column G for the condensation of the phosphorus is closed at top by a
hydraulic cover b which can easily be lifted off to clear out the tubes d, through
which the gases and vapors of phosphorus pass. At the bottom of the tubes d is a
rose or ring pierced with holes e on the inner side and fed by an external pipe g;
the water falling in a fine shower coupletes the coudensation of the vapors of
phosphorus.
+
The phosphorus is collected at the lower part of the column G in the water of
the trough H.
And having now described the nature of the said Invention, and in what manner
the same is to be performed, I declare that I claim as "The Improvements in the
Manufacture of Phosphorus,"
First. The preparation in the form of blocks or bricks of intimate mixtures, aud
in suitable proportions, of phosphates of lime, baryta, or other earthy phosphates,

page_text: and of silica or other silicious body bound or held together by a carburetted
body, such as tar, pitch, or coal, substantially as and for the purpose herein before
described.
Second. The extraction of the phosphorus from the said earthy phosphates
previously made into blocks or bricks, with silica or a silicious body, by the process
based upon known reactions, and employing for this purpose ordinary retorts or
other suitable distillatory apparatus, but by preference a blast furnace similar to
those used in smelting iron, substantially as herein before described.
Third. The particular construction of apparatus, shown in the annexed Drawing,
consisting of a furnace and a condenser combined therewith, and acting as and for
the purpose described.
In witness whereof, I, the said John Clayton Mewburn, have hereunto set
my hand and seal, this Twenty fourth day of June, One thousand eight
hundred and seventy nine.
J. C. MEWBURN. (L.S.)