Improvements in the Manufacture of Nitrate of Ammonium, and in the Apparatus therefor.
Year: 1896

page_text: Date of Application, 18th Mar., 1906
Complete Specification Left, 16th Dec., 1896-Accepted, 6th Feb., 1897
'
Date
prication
Complete Specification Left, 16th Dec., 1896-Accepted, 6th Feb., 1897
P. OVISIONAL SPECIFICATION.
Improvements in the Manufacture of Nitrate of Ammonium, and
in the Apparatus therefor.
I, GEORGE CRAIG of George Square, Glasgow, Scotland, Chemist, do hereby
declare the nature of this invention to be as follows:-
According to my present invention I heat mixtures of nitrate of potash, nitrate
of soda or both with sulphate of ammonia in sufficient excess and with sufficient
water to ensure thorough double decomposition.
The resulting mixture is or may be dried until anhydrous, and then kept
agitated or stirred until it forms a loose powder which is treated with (high
strength) ammonia, (which may be anhydrous or hydrated to some extent) which
dissolves the nitrate of ammonium leaving the mixed sulphates of potash, soda
and ammonia insoluble. The use of such high strength ammonia, exerting if
anhydrous from 8 to 10 atmospheres of pressure necessitates the employment of
strong vessels. If a weaker ammonia be used the pressure requiring to be pro-
vided for is much less; thus with liquid of 800 sp. gr. about 2 atmospheres will
be exerted and less pure nitrate of ammonium produced.
The apparatus and operation is as follows: An extraction vessel of suitable
material and strength and containing or combined with a suitable filter appliance
is charged with the aforesaid mixture or powder and treated with ammonia of
aforesaid strenths or quality: it may be digested therewith for some time or
simply percolated and allowed to run off through the filter into another vessel
or compartment. By means of a pump in suction connection with the atmosphere
of this filtrate vessel, the volatile ammonia is removed, compressed and liquefied
by suitable means and returned to the extraction vessel to dissolve a further
quantity of nitrate of ammonium. This cycle of operations is continued until
the extraction is as complete as desired. The ammonia is withdrawn from the
apparatus, and its contents, aiding its expulsion by heat if necessary. The nitrate
of ammonium is removed from the filtrate vessel, or the product from several
extractions may be allowed to accumulate, in which case the expulsion of ammonia
from that vessel is unnecessary, the exhausted salts removed from the extractor,
fresh powder introeduced and the operation recommenced.
When the weaker strengths are employed a more or less impure nitrate of
ammonium results and may be treated by fractional precipitation aided by double
decomposition. Instead of obtaining said nitrate in the dry state it may be in
aqueous solution from which the ammonia has be abstracted and require
evaporation to dryness. The weaker ammonia may be obtained by distilling
apparatus the condenser controlling the strength of the liquid. The pressure in
the distilling apparatus may be made to condense the ammonia desired, and
deliver to the extractor without the use of a pump.
Dated this 19th day of Man 1806
D. F. MASON,
Glasgow, Patent Agent.

page_text: Improvements in the Manufacture of Nitrate of Ammonium, and
in the Apparatus therefor.
I, GEORGE CRAIG of 24 George Square, Glasgow, Scotland, 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 relates to a new or improved treatment for the extration or
purification of nitrate of ammonium from mixtures containing it which have been
derived from former operations.
In carrying out my invention I heat mixtures containing nitrate of potash,
nitrate of soda, or both with sulphate of ammonia in sufficient excess and with
sufficient water to ensure thorough double decomposition. The resulting mixture
is dried (but not necessarily until anhydrous) and the hot pasty mass is kept
agitated or stirred while cooling when it forms a loose powder.
According to my invention the cold powder is treated with anhydrous or high
strength aminonia which dissolves the nitrate of ammonium and leaves the mixed
sulphates of potash, soda and ammonia insoluble. The use of such high strength
ammonia exerting, if anhydrous from 8 to 10 atmospheres of pressure necessitates
the employment of strong vessels but owing to the low temperature obtaining in
practice the pressure is reduced to about 4 atmospheres in the most of the
apparatus except the condenser and pump. If a weaker ammonia be used the
pressure requiring to be provided for is much less; thus with liquid of '800 specific
gravity about 2 atmospheres will be exerted; but a more or less impure nitrate of
ammonium is produced.
As ammoniacal solutions of nitrate of ammonia exert strong corrosive action on
many metals, iron or steel for instance, all vessels and pipes which may contain or
come in contact with such solutions must be of suitable material, barffed or
enamelled iron, or tinned or aluminium lined iron.
The operation prefer to carry out as follows:-An air tight extraction
vessel (a) of suitable material and strength and containing or combined with a
suitable filter appliance (b) is charged with the aforesaid mixture or powder and
treated by digestion or percolation with ammonia of aforesaid strength or quality
which may be stored in the condenser (c) or cylinder in connection with apparatus
or produced directly from suitable apparatus. The colder the temperature at
which this treatment is carried out the lower is the pressure in the apparatus and
the purer also is the resulting product. It is also desirable to have the ammonia
in considerable excess. The filtrate may contain 80% of its weight of nitrate of
ammonia, but as such strong solutions may dissolve some of the other salts it is
best to work so that the filtrate contains less, say 50 to 60% when this is entirely
avoided. The resulting solution is allowed to run off through the filter (b) into a
filtrate vessel (c).
By means of a pump d in suction connection with the atmosphere in filtrate
vessel e the volatile ammonia is removed and compressed through condenser c and
thereby liquified, and returned by pipe fto extraction vessel a to dissolve a further
quantity of nitrate of ammonium. This cycle of operations is continued until the
extration is as complete as desired, and the ammonia may be recovered from the
moist residue in vessel a by the aid of suction and heat if necessary. The nitrate
of ammonium remaining in the filtrate vessel e may be recovered as desired by
removing the volatile ammonia by suction and beat in the same way, leaving the
nitrate of ammonia as a white mass in bottom of vessel e from which it may be

page_text: removed by manhole i. When the exhausted mixture is removed from the
extractor a fresh powder is introduced and the operation recommenced.
When the weaker strengths of ammonia are employed a more or less impure-
nitrate of ammonium results. It contains sulphates of potash, soda or ammonia
according to the mixtures employed and may be separated therefrom by fractional
precipitation, double decomposition, by treatment with stronger ammonia or other
suitable means. An aqueous solution of nitrate of ammonium is obtained in this
case from which the salt may be recovered by evaporation. By suitably regulating
the condenser of the ammonia generator when such is employed, such weaker
ammonia may be obtained as desired.
The cold produced in the filtrate vessel e may be rationally utilized for the
condensation of the ammonia. This may be easily accomplished by exten ling the
condensing pipe (as indicated by dotted lines c¹) to encircle or incircle the filtrate
vessel e before connecting with extrating vessel a. Otherwise the filtrate vessel e
may obviously be placed inside the condenser or may enclose the condenser. The
pressure necessary for condensing the ammonia is thus or may be reduced to a
minimum.
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.
1. The extraction of nitrate of ammonium from mixtures coutaining it, by
treatment with anhydrous or high strength ammonia, substantially as described.
2. The purification of impure nitrate of ammonium by treatment with anhydrous
or high strength ammonia, substantially as described.
3. The arrangement and combination of apparatus as and for the purposes
specified and shewn.
4. In apparatus as herein before specified, utilizing the cold of the evaporating
ammonia for cooling ammonia being coudensed, by encircling or incircling the
filtrate vessel with the condenser pipe or other condensing appliance, substantially
as hereinbefore set forth.
Deted this 15th day of December 1896
D. F. MASON,
Glasgow, Patent Agent.