Process and Apparatus for Producing Phosphorus.
Year: 1888

page_text: Date of Application, 18th Oct., 1888
Complete Specification Left, 17th July, 1889-Accepted, 21st Sept., 1889
PROVISIONAL SPECIFICATION.
Process and Apparatus for Producing Phosphorus.
JAMES BURGESS READMAN, Doctor of Science, India Buildings, Edinburgh
Analytical and Consulting Chemist do hereby declare the nature of this invention to
be as follows:
:-
In the ordinary method of producing Phosphorus it is customary to heat the selected
and prepared phosphatic material to a high temperature in fire clay or earthenware
cylinders or retorts by means of an external fire, consuming either carbonaceous
or gaseous fuel. The material, which is introduced into these vessels, is generally a
desiccated mixture of crude phosphoric acid or acid phosphate of lime intimately
mixed, when in solution, with charcoal, coke; or other carbonaceous substance.
Again, other substances containing Phosphorus in combination with a metal or
base are employed but in such cases it is sometimes necessary to use, in conjunction
with the carbonaceous material, silica, or other acid or basic matter, or salts to liberate
the Phosphorus. The cylinders or retorts, before referred to, are connected with
condensers, and, when the necessary temperature has been attained, Phosphorus distils
off and is condensed under water.
The very high temperature to which the mixed materials require to be submitted
in order to effect complete reduction and liberation of Phosphorus, in the elementary
state, occasions an excessive wear and breakage of the fireclay cylinders or retorts,
which leads to great loss of material, and largely increases the cost of production.
My improved method of producing Phosphorus aims at economy in this direction.
Instead of applying heat to the external surface of vessels containing the Phosphorus-
yielding material mixed as usual with carbonaceous matter, I direct the source of heat
into and through these materials themselves, maintaining a reducing atmosphere
within the vessel and keeping up, at the same time, the excessive heat required for the
decomposition. To accomplish this I employ, by preference, one or other of the
familiar forms of, what is known as, the Electric Furnace. The vessel, or set of
vessels, in which the decomposition is conducted may be placed in any suitable
position, horizontal or inclined but I prefer to place them vertical and provide each
one with an outlet above which I connect with an ordinary condensing arrangement,
and with or without an outlet beneath, by which the exhausted residue may be with-
drawn. The charging of the vessel is effected by means of a door or cover on the
top, through which door or cover one of the electrodes may be made to pass.
I take a solution (1) containing Phosphoric acid, or acid phosphate of lime, and,
after concentrating it by evaporation, I thoroughly incorporate with it, carbon or
carbonaceous material, and I expel the remaining moisture by careful desiccation or,
(2) I take bone ash, or one or other of the alkaline, earthy, aluminous or other
metallic Phosphates or, (3) once more, I take one or other of the metallic phosphides.
Whichsoever of these dry, solid phosphates or phosphides I employ, I mix it at once
with sufficient carbon for the complete reduction and liberation of the whole of its
contained phosphorus, adding, if required, silica or a silicious material, an aluminous,
or other basic or acid substance, or substances, as flux, to combine at high
temperature with the earthy, aluminous or other metallic constituents of the phosphatic
material.
Having charged the furnace with one or other of the Phosphorous-bearing mixtures
I carefully lute the furnace and establish a free connection between it and the
condensing arrangement. I then pass the electric current through the mixture and
thus obtain in a speedy and economical way practically the whole of the Phosphorus
existing in the Phosphatic material selected for treatment.
1-
1
1
1000

page_text: COMPLETE SPECIFICATION.
Process and Apparatus for Producing Phosphorus.
I, JAMES BURGESS READMAN, of India Buildings; Edinburgh, in the County of
Mid Lothian, Doctor of Science, 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, that is to say :-
In the ordinary method of obtaining phosphorous it is customary to heat the
selected and prepared phosphatic material to a high temperature in fireclay or
earthenware cylinders or retorts by means of an external fire consuming solid or
gaseous carbonaceous fuel. The material introduced into the retorts is generally a
desiccated mixture of crude phosphoric acid or acid phosphate of lime intimately
mixed, when in solution with charcoal, coke, or other carbonaceous substance. Some-
times other substances containing phosphorus in combination with a metal or base are
employed but in such cases it is frequently necessary to use in conjunction with the
carbonaceous material silica or other acid or basic matter or salts, in order to liberate
the phosphorus. The cylinders or retorts are connected with condensers, and when
the necessary temperature has been attained phosphorus distils over and is condensed
under water. The very high temperature which has to be employed to effect completo
reduction and liberation of phosphorus, occasions excessive wear and breakage of the
fireclay cylinders or retorts, leading to great loss of material and largely increasing
the cost of production.
My Invention has for its object to diminish the wear of the apparatus, and the waste
and loss of materials; and in carrying out my Invention instead of applying heat to
the external surface of vessels containing the phosphorus-yielding material mixed, as
usual, with carbonaceous matter, I generate the heat within the containing vessel, and
apply it directly into and through the materials themselves, at the same time
maintaining a reducing atmosphere within the vessel, and keeping up the temperature
required for the decomposition. In order to accomplish my purpose 1 employ a
suitable adaptation of what is known as an electric furnace such as is shown on the
accompanying sheet of explanatory drawings. I do not however restrict myself to
any precise construction of the electric furnace.
Figure, 1, of the drawings is a plan, and figures, 2, and 3, are vertical sections as
at right angles to each other.
The furnace is formed in a building or structure, A, of fireclay or other suitable
refractory material the furnace chamber, B, being of a rectangular form, open at the
top but covered by a removable fireclay slab, C. At one side of the furnace
chamber, B, there is a partly inclined passage, D, for the introduction of materials,
there being at the outer and upper end of this passage a hopper, E, with two
valves, F, G. At the opposite side of the furnace chamber, B, there is an outlet, H,
provided with a pipe, J, for leading off the vaporised phosphorus to a condenser. At
the other two sides of the furnace sets of carbon electrodes, K, are made to project
into the chamber, B, with their inner ends facing each other and a short distance apart.
Each set of carbon electrodes, K, is fixed in a castiron block, L, which has fixed to it
a copper bar, M, extending out through the end cover of a casing, N, in which the
block; L, is placed. To give convenient access to the block, L, and the electrodes, K,
the casing, N, is made with its upper half removable. The copper bar, M, is formed
with a crosshead, P, on which are strung. and fixed a number of conductors, Q.
These conductors, Q, are to be connected to a dynamo-electric machine or other
suitable source of electricity those from one side of the furnace going to the positive
and those from the other side to the negative pole.
The phosphorus-yielding materials are to be placed in the furnace chamber, B, so
as to occupy its centre between and in the immediate neighbourhood of the inner
ends of the electrodes, K, and so as to be embedded in and surrounded by coke or
charcoal in moderately sized pieces. The bottom or bed of the furnace may be
formed with silicious materials or a suitable metallic phosphide or with materials

page_text: such as
are ordinarily used for the beds of puddling or other reverberatory
furnaces.
In preparing the phosphorous yielding materials I may take a solution containing
phosphoric acid, or acid phosphate of lime, and after concentrating by evaporation
I thoroughly incorporate with it carbon or carbonaceous material, and I expel the
remaining moisture by careful desiccation. Or I may take boneash, or one or other
of the alkaline, earthy, aluminous, or metallic phosphates; or may take any metallic
phosphide which will yield its phosphorus or a large part of it. I mix one or
more of the materials with sufficient carbon for the reduction and liberation of the
obtainable phosphorus, adding if required silica or silicious material, or aluminous
or other basic or acid substance or substances as a flux to combine at a high
temperature with the alkaline, earthy, aluminous, or metallic constituents of the
phosphatic material.
By way of example I will now give particulars of charges which may be treated
in carrying out my invention. In forming a charge I take 100 pounds native
phosphate of alumina, such as Redonda phosphate, in a crushed or ground condition,
and after mixing it with 20 pounds of carbon, or an equivalent quantity of
carbonaceous material such as tar or pitch, I carefully expel all matters volatile at
a dull red heat, and I introduce the desiccated mixture into the electric furnace.
Or I may take 100 pounds of a phosphate of lime, such as Spanish or French
phosphate, and mix with it 25 pounds Redonda phosphate 35 pounds sand, and
25 pounds carbon or an equivalent quantity of carbonaceous material, and after
expelling all matters volatile at a dull red heat, I introduce the mixture into the
electric furnace. Or again I may take, 100 pounds Spanish phosphate of lime,
45 pounds sand and 20 pounds carbon and treat the mixture as in the other
examples.
Having charged the furnace with one or other of the phosphorus-yielding materials
hereinbefore referred to, I carefully lute the furnace, and then cause to pass through
it an electric current of sufficient intensity to produce incandescence at the centre
of the furnace with the result that the phosphorus is rapidly reduced and distilled
over.
Having now particularly described and ascertained the nature of my said 'Inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
:-
The process of obtaining phosphorus by subjecting materials containing it to heat
generated by an electric current and applied directly to the materials contained
within a furnace, the process and apparatus being substantially such as are herein- .
before described.
Dated this Fifteenth day of July 1889.
EDMUND HUNT,
Applicant's Agent.