Improvements in and relating to a Process for the Treatment of Phosphorites or other Phosphatic Material.
Year: 1891

page_text: Date of Application, 2nd June, 1891-Accepted, 4th July, 1891
COMPLETE SPECIFICATION.
Improvements in and relating to a Process for the Treatment of
Phosphorites or other Phosphatic Material.
I, CHARLES GLASER, a citizen of the United States of America, residing at
No. 227 East German Street, in the City and County of Baltimore and State of
Maryland, one of the United States of America, Manufacturer and 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 :-
My invention consists in a new and useful process for the treatment of
phosphorites, or other phosphatic material, containing a portion of their phosphoric
acid. in combination with alumina, with the twofold result of (1st) freeing such
material from its phosphate of alumina, and (2nd) of converting this separated
phosphate of alumina to a more soluble condition, and so rendering it fit for
fertilizing purposes.
My process is based on the following reactions: If finely divided phosphate of
alumina, or phosphorite containing the same, be digested in a sufficient solution of
an alkali, with or without heat, or in a like solution of the carbonate or phosphate
of an alkali with heat, all the phosphate of alumina present will be dissolved.
If now the alkaline solution be treated with carbonic acid at ordinary
temperatures (or better, under cooling), or if the carbonate (or phosphate) solution
be allowed to cool, in either case nearly all the phosphate of alumina will be
precipitated, and, when separated and washed, will be found nearly pure, and also
soluble in the standard solution of citrate of ammonia at 150° Fahrenheit, thus
meeting that approved test of availability for manurial purposes.
The liquid if heated again, or restored to an alkali solution by treatment with
lime, will recover, for the most part, its solvent power.
My process, generally described is as follows:
1 treat the phosphorite or other material, in a finely divided state, with the
solution of an alkali or with the hot solution of the carbonate of an alkali, either
digesting or leaching until all the phosphate of alumina is dissolved. I then
separate the solution so formed, thus freeing the material (in residuum) from its
phosphate of alumina, and so attaining one of the objects proposed.
I then proceed to precipitate the phosphate of alumina from the solution. This
I do in the case of the alkali solution (used as a solvent) by introducing carbonic
acid, either in the form of gas, or by the addition of carbonates, but in the case of
the hot carbonate solution simply by cooling. In either case the same result
follows, viz., precipitation of phosphate of alumina, and this being separated
(as the desired product) I have left a liquid which I render available again as a
solvent, either by simply heating or by regenerating to an alkali solution (in a well
known manner) by treatment with lime.
In the above described process, the phosphate of an alkali can be used instead of
the carbonate of an alkali, having a like solvent effect though in less degree.
I will now show by the two following examples the best way known to me of
carrying out my process, with the special precautions to be taken.
EXAMPLE 1.-USING SOLUTION OF AN ALKALI.
Take a convenient amount of phosphate of alumina, or mineral containing same,
reduced to a finely divided state, put in a suitable vessel and digest with the
solution of an alkali for example sodium hydroxyd-sufficient to insure complete

page_text: (Instead of digesting it may be advantageous to digest and leach the material by
several successive applications of the alkaline solution, arriving at the same result,
viz., a saturated solution.)
Ćare should be taken to use not less than one hundred and sixty-five parts of
sodium hydroxyd to one hundred parts of phosphate of alumina, though an excess
may be found advantageous.
Again, care must be taken to use the solution of the alkali in such a degree of
concentration as to avoid, on the one hand, solidification of sodium aluminate and
sodium phosphate upon cooling, and on the other hand, precipitation of alumina
hydroxyd under the subsequent treatment with carbonic acid. The former will
happen if the solution is too concentrated, the latter if it is too dilute. The degree
recommended in the example proposed is a solution containing between five and
fifteen
per
cent. of sodium hydroxyd.
Having completed the solution, separate it from the insoluble residue. This in
the case of phosphate of alumina being treated, will consist chicfly of silicates and
impurities, but when treating phosphorites will contain other phosphates (as
of lime) and these will be the more valuable for being freed from phosphate of
alumina.
The solution containing, it is supposed, aluminate and phosphate of sodium, with
perhaps a little free alkali, is now saturated with carbonic acid, either by addition
of a bi-carbonate or by introducing carbonic acid gas. For the best results the
solution should be cold at this stage, as it will be found, if hot, to retain much
phosphate of alumina in solution.
The precautions indicated having been observed, the greater part of the alumina
and phosphoric acid will now be precipitated as phosphate of alumina, and may be
separated from the liquid by decantation, filtration, or otherwise.
I recommend the use of filtering presses for this, both to allow complete washing
and recovery of the carbonate, and to obtain the precipitated phosphate in con-
venient form to handle and dry; and in drying it I prefer a low degree of heat,
not much exceeding 212° Fahrenheit, as a higher degree is apt to impair
solubility.
The filtered liquid containing chiefly carbonates of alkalies, though still retaining
in solution a small part of the phosphate of alumina is now regenerated, by
boiling with lime or equivalent, to an alkaline solution, and used as such for a
repetition of the above process, or, without such treatment, is heated and used as a
solvent in the process described in the following example.
EXAMPLE 2.-USING CARBONATE SOLUTION.
Take, as before, a convenient amount of the phosphate of alumina or phosphorite
and digest same with a hot solution of carbonate of an alkali, as, for instance,
sodium carbonate, containing enough of the carbonate to dissolve all the phosphate
of alumina, but at the same time dilute enough to prevent crystallization of the
carbonate upon cooling. In this instance not less than two hundred and fifteen
parts of sodium carbonate to one hundred parts of phosphate of alumina are
recommended, though some excess may be found advantageous. (Instead of
digesting, leaching may be used as suggested before, but the liquid should
not be allowed to cool until the solution is completed and the residuum
separated).
When the phosphate of alumina is all dissolved, separate (as before) the
insoluble residue.
The separated solution is now allowed to cool and the phosphate of alumina
thereby precipitated, to settle. Sufficient time must be allowed for this, as the last
portions of the precipitate form slowly. When completely settled the precipitate
is separated and treated as prescribed in the preceding example, and the remaining
liquid is in like manner available as a solvent for a new operation.

page_text: 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 separating phosphate of alumina from minerals containing the same,
and producing therefrom high grade precipitated phosphate of alumina by successive
stages as follows:-First, treating the mineral with the solution of an alkali or with
the hot solution of the carbonate (or phosphate) of an alkali, until all the phosphate
of alumina is dissolved:
Next, separating the solution so formed:
Next, treating it with carbonic acid if made with an alkali, or cooling it if made
with the carbonate or equivalent, in either case causing precipitation of phosphate
of alumina :
Next, separating this precipitate, as the product of the process:
Finally, utilizing the remaining liquid as a solvent for a new operation of the
process, either directly as a carbonate (or equivalent) solution, or, after regeneration
by lime, as an alkali solution, all substantially as described.
,
יזי
1001
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.
Can no SORT
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.