Improvements in the Process of Manufacturing. Phosphorus and other Materials.
Year: 1898

page_text: Date of Application; 5th May, 1898-Accepted; 30th July, 1898
COMPLETE SPECIFICATION.
Improvements in the Process of Manufacturing. Phosphorus and
other Materials.
1
We, CHARLES SCHENCK BRADLEY, of Avon, County of Livingston, and State of
New York, U.S.A., Electrical Engineer, and CHARLES BORROWS JACOBS, of East Orange,
County of Essex, and State of New Jersey, U.S.A., Chemist, 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 object of my invention is to permit a cheaper' extraction of phosphorus than
has heretofore been possible and to provide for the formation of residual products by the
process of reduction. In carrying out my invention I subject raw materials containing
phosphorus, such for instance as rock phosphate, burnt bones or any of the natural
or manufactured phosphates of calcium and sufficient carbon to combine with all the
oxygen of the phosphorus bearing material and to unite with the calcium for 'the
formation of calcium carbide, to the heat of an electric furnace generated by the passage
of from 25 to 50 kilowatts. The products of this reaction are phosphorus which
distills off and may be collected under water, and calcium carbide which remains in
the furnace as a residuum. No special, type of electric furnace is necessary except
that suitable connections should be made with the dome of the furnace for a pipe to
lead the distilled phosphorus into a condensing tank or vessel.
In the accompanying drawing I have illustrated a form of apparatus convenient for
carrying out the process in which,
Figure 1 is a sectional view of an electric furnace and condensing chamber; and
Figure 2 is a sectional plan of part of the apparatus.
Referring to the drawings 1 represents an iron or steel shell lined with carbon or other
suitable refractory matérial and provided with a dome, as indicated, into which extends
carbon-electrodes 2, 3, for carrying an electric current of from 25 to 50 kilowatts, one
of the electrodes being adjustable in a way well understood by those familiar with the
manipulation of electric furnaces, to render convenient the springing of an are between
the abutting terminals of the electrodes. The furnace is preferably provided with an
inclined hearth 4 of carbon and a feed pipe 5 above the level of the charge, with which
communicates a feed-hopper 6 having a suitable gate 7 and a worm 8 by which the
material may be fed into the furnace. At a point above the level of the charge and
preferably above the springing point of the arch is provided a pipe 9 which leads
below the level of the water contained in a condensing tank 10. At the lower
point of the hearth is provided a door lined with fire-proof material 11 which is
adapted to be quickly secured in place or detached by cleats or catches 12, 13.
In operating the furnace a charge of 'ground rock phosphate or other phosphorus-
bearing material mixed with ground coke or carbon sufficient to combine with all
of the oxygen of the phosphorus-bearing material and enough more to combine
with the calcium or other inetallic base of the phosphorus to form a carbide is
heaped upon the hearth of the furnace. Assuming for example, that normal
calcium phosphate Ca, (PO) 2 is the raw material to be reduced, the theoretically
correct mixture for the liberation of the phosphorus and the formation of calcium
carbide would be 310 parts by weight of normal calcium phosphate to 168 parts

page_text: by weight of carbon; in practice, however, it is preferable to use 200 parts by
weight of carbon in the form of ground coke or small anthracite to 310 parts of
calcium phosphate. The raw material should be ground before mixing in order
to insure a homogeneous mixture.
The reaction may be stated as follows:-
The phosphorus in the form of vapor is carried through the pipe 9 and
discharges below the level of the water into the condenser 10 where it accumulates
and may be removed from time to time.
After charging the furnace as above described, the arc is started the dome
acting as a reflector to concentrate the heat upon the ore or raw material, and
after a period of time, depending upon the quantity of the charge, a liquid mass
of fused carbide of calcium will form on the hearth of the furnace and may
be removed from the tap hole near the hearth by withdrawing. the plug 11.
During the process the phosphorus is distilled off until all of it has been
extracted. As the operation continues fresh portions of mixed raw materials may
be added from the hopper 6 so as to make the operation continuous. A charge of
310 pounds of normal calcium phosphate and 200 pounds of ground coke will yield
under the treatment above described 192 pounds of calcium carbide and 62 pounds of
phosphorus.
The invention may also be carried out with other phosphorus-bearing materials
than the phosphates as for example phosphides or phosphates or other compounds of
other bases than calcium and in such cases the amount of carbon used will vary
according to the chemical nature of the material, being preferably always sufficient to
produce a by-product of carbide of the metallic base.
If calcium phosphide for example be employed the following reactions will occur :-
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we declare that what we claim
is:-
1. The process of extracting phosphorus from a phosphorus-bearing material
consisting in mixing said material with sufficient finely divided carbon to liberate the
phosphorus and combine with the metallic base to form a carbide, then subjecting
the mass to the heat of an electric furnace, then condensing the phosphorus.
2. The process of extracting phosphorus from normal calcium phosphate which
consists in inixing the latter with sufficient carbon to combine with all of the oxygen
and calcium and subjecting it to the heat of a closed electric furnace and leading off
and condensing the phosphorus thereby forming a residuum of calcium carbide.
Dated the 5th day of May A.D. 1898.