Improvements in the Manufacture and Purification of Ammonium Nitrate and other Salts.
Year: 1896

page_text: Date of Application, 23rd Jan., 1896
Complete Specification Left, 23rd Oct. 1896-Accepted, 23rd Jan., 1897
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture and Purification of Ammonium
Nitrate and other Salts.
I, THOMAS FAIRLEY of 17 East Parade, Leeds in the County of York, Chemist,
do hereby declare the nature of this invention to be as follows:-
The object of this invention is to obtain ammonium nitrate by the reaction of
ammonium sulphate or other ammonium salt on sodium or potassium nitrates, in a
pure state-containing less than one per cent. of any fixed or solid impurity.
When the salts are mixed in the proportions of 132 parts of ammonium sulphate
to 170 parts of sodium nitrate they react together and enter into partial fusion when
heated to 108° to 110° Centigrade. They should be constantly stirrel during the
heating so as to secure a uniform temperature throughout the mass. If the salts
are perfectly dry the addition of a very small proportion of water facilitates the
reaction-but if the salts are not quite dry-the hygroscopic water present may be
sufficient. When the whole mass of mixed salts has attained the temperature of
say 108° to 110° C. the heat is continued from three to five minutes. A small
portion of ammonia is given off and further heating only increases this loss. When
water is added to the salts during or before the heating I prefer to add water
containing free ammonia so as to diminish the loss of ammonium during the
heating.
The product of the reaction carried out as above stated is a mass consisting
chiefly of ammonium nitrate and sodium sulphate, with certain proportions, stated
below, of unchanged sodium nitrate and ammonium sulphate. The reaction cannot
be made complete and I have proved that a mass of the same composition can
be obtained by heating to 108° to 110° C. the pure salts in the proportions of
160 parts of ammonium nitrate to 142 parts of anhydrous sodium sulphate.
On treating the mass obtained as above from ammonium sulphate and sodium
nitrate with strong boiling alcohol in any extraction apparatus-ammonium
nitrate mixed with about 10 per cent. of sodium nitrate enters into solution and
sodium sulphate containing about 8 per cent. of ammonium sulphate remains
undissolved. The ammonium nitrate contained in the alcoholic solution cannot be
freed from the 10 per cent. of sodium nitrate present by filtering the liquid through
a layer of ammonium sulphate at the temperature of the boiling alcohol, nor at any
ordinary temperatures. Even a very large excess of ammonium sulphate heated
with sodium nitrate as above and extracted still gives ammonium nitrate containing
about 10 per cent. of sodium nitrate.
During the extraction of the mixed salts by boiling alcohol some ammonia is
given off and if not perfectly condensed and restored to the liquid the latter
becomes acid and of a dark colour which is communicated to the salts left after
evaporation or crystallizing out from the alcohol. The free acid present in the
liquid also corrodes metals if such be used in any part of the extraction apparatus.
I have proved that a very small proportion of free ammonia present in the alcohol
used which need not be more than 1 per cent. and ought not to be less than 0.2 per
cent, is sufficient to prevent discoloration of the salts and to perfectly protect such
metals as iron, steel, lead or tin if used in the construction of the apparatus or any,
part of it exposed to the liquid or its vapour. In practice I use ordinary
methylated spirit; containing 85 to 93 per cent. real alcohol and to it I add ammonia.

page_text: corresponding to about 0.5 per cent. of the alcohol. When the alcohol is condensed
and used repeatedly in the extraction process the cold condenser should be as near
as possible to the working part of the extraction apparatus to diminish or prevent
loss of ammonia.
A suitable extractor may be employed for the extraction with alcohol and also
for purifying the mixed salts obtained.
For the purification of the mixed nitrates the following process will be found
simple and efficient. The mixed nitrates of ammonia and sodium obtained in the
solid form either by distilling off the alcohol or by crystallizing out during the
cooling of hot alcohol are dried in a ciosed apparatus so that no alcohol is lost.
They are then finely powdered and placed in an upright cylindrical or other
percolator and subjected to the solvent action of a very slow stream of either cold
water or of cold saturated solution of ammonium nitrate. In a short time the upper
part of the column of salt is purified so as to consist of pure ammonium nitrate. To
facilitate this operation, the mixed salts may be fed into the bottom of the
percolator or extractor and then gradually elevated-the purified salt being
meanwhile removed from the top of the percolator. In this apparatus by proper
regulation of the liquid supplied and of the salt-the process of purification can
be made nearly automatic and continuous-so long as the necessary power is
supplied.
The moist purified ammonium nitrate discharged from the top of the percolator
is then dried and is ready for use.
The liquid from this percolator contains when worked at ordinary temperatures,
in solution about 2 parts of animonium nitrate to 1 part of sodium nitrate. These
salts are recovered by evaporation and added to the next supply of materials
treated.
Finally the sodium sulphate remaining from the alcoholic extraction contains
about 8 per cent. of ammonium sulphate. This can be recovered by treating the
mixed sulphates with hot or boiling water in a percolator as described above. All
the ammonium sulphate dissolves out into the water issuing from the percolator along
with a smaller quantity of sodium sulphate. This liquid containing the ammonium
sulphate can be evaporated and added to the next lot of materials so that neither
ammonium salts nor nitrates are lost or wasted in the process.
In many cases the sodium sulphate left will be a waste product; if of any value
where produced it can be dried for use.
Dated this 23rd day of January 1896.
BOULT & WADE,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Manufacture and Purification of Ammonium
Nitrate and other Salts.
1, THOMAS FAIRLEY of 17 East Parade, Leeds in the County of York, 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 this invention is to obtain ammonium nitrate by the reaction of
ammonium sulphate or other ammonium salts on sodium or potassium nitrates so
that the ammonium nitrate may be pure or contain less than one per cent. of fixed
or solid impurity.
When the salts are mixed in the proportions of 132 parts of ammonium sulphate
to 170 parts of sodium nitrate and heated to 108° to 110° Centigrade they react

page_text: ogether and enter into partial fusion. They should be constantly stirred and
nixed during the heating so as to secure a uniform temperature throughout the
mass. If the salts are perfectly dry the addition of a very small quantity of water
acilitates the reaction, but if the salts are not quite dry the hygroscopic moisture
present may be sufficient. When the whole mass has attained the temperature-
of say 108° to 110° Centigrade the heat is continued from three to five minutes..
A small portion of ammonia is given off and further heating only increases this
s. When water is added to the salts during or before the heating I prefer to
add water containing free ammonia so as to diminish the loss of ammonia during
the heating.
Joss.
The product of the reaction carried out as above stated is a mass consisting
chiefly if ammonium nitrate and sodium sulphate with certain proportions state-
below of sodium nitrate and ammonium sulphate. The reaction cannot be made.
complete and I have proved that a mass of the same composition can be obtained'
by heating to 108° to 110° C., the pure salts in the proportions of 160 parts of
ammonium nitrate to 142 parts of anhydrous sodium sulphate.
On treating the mass obtained as above from ammonium sulphate and sodium
nitrate-with strong boiling alcohol in any extraction apparatus ammonium nitrate
mixed with about 10 per cent. of sodium nitrate enters into solution and sodium,
sulphate mixed with about 8 per cent. of ammonium sulphate remains undissolved.
The ammonium nitrate contained in the alcoholic solution cannot be freed from
the 10 per cent. of sodium nitrate present, by filtering the liquid through a layer
of ammonium sulphate at the temperature of the boiling alcohol-nor at any
ordinary temperature. Even a very large excess of ammonium sulphate heated
with sodium nitrate as above described still gives ammonium nitrate containing
about 10 per cent. of sodium nitrate.
During the extraction of the mixed salts by boiling alcohol some ammonia is
given off and if not properly condensed and restored to the liquid, the latter
becomes acid and of a dark colour which is communicated to the salts left after
evaporation or crystallizing cut from the alcohol. The free acid present in the
liquid also corrodes metals if such be used in the construction of any part of the
extraction apparatus. I have proved that a very small proportion of free ammonia
present in the alcohol used which need not be more than 1 per cent. and ought not to
be less than 0.2 per cent. is sufficient to prevent discoloration of the salts and to-
perfectly protect such metals as iron, steel lead or tin if used in the construction of
the apparatus or any part of it exposed to the liquid or its vapour.
In practice I use ordinary methylated spirit, containing 85 to 93 per cent., real
alcohol and to it 1 add ammonia corresponding to about 05 per cent. of the alcohol..
When the alcohol is condensed and used repeatedly in the extraction process the
cold condenser should be as near as possible to the working part of the extraction
apparatus to diminish or prevent loss of ammonia.
A suitable extractor may be employed for this extraction with alcohol and also
for purifying the mixed salts obtained.
For the purification of the mixed nitrates the following process will be found
simple and efficient. The mixed nitrates of ammonium and sodium obtained in the
solid form either by distilling off the alcohol, or by crystallizing out during the
cooling of the hot alcohol are dried in a closed apparatus so that no alcohol is.
lost. They are then finely powdered and placed in an upright cylindrical er other
percolator and subjected to the solvent action of a very slow stream of either cold
To facilitate this.
water or of cold saturated solution of ammonium nitrate.
operation the mixed salts may be fed into the bottom of the percolator and then
gradually elevated, the purified salt being meanwhile removed from the top of the
percolator.
In this apparatus by proper regulation of the liquid supplied at the upper end
and of the salt supplied at the lower end of the percolator, the process of purifica-
tion can be made nearly automatic and continuous so long as the necessary power is.
supplied.

page_text: The moist purified ammonium nitrate discharged from the top of the percolator
is then dried and is ready for use.
The liquid from this percolator contains when worked at ordinary temperatures,
in solution about two parts of ammonium nitrate to one part of sodium nitrate.
These salts may be recovered by evaporation and added to the next supply of
materials treated...
Finally the sodium sulphate remaining from the alcoholic extraction containing
about 8 per cent. of ammonium sulphate may be treated with hot or boiling water
in a percolator as described above. All the ammonium sulphate dissolves out into
the water issuing from the percolator along with a smaller quantity of sodium
sulphate. This liquid can be evaporated and added to the next supply of materials
so that neither ammonium salts nor nitrates are lost in the process.
The sodium sulphate if of value where it is produced can be dried for use.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is ;-
1. The process herein described for the manufacture of pure ammonium nitrate.
2. In the manufacture of ammonium nitrate the employment of a solvent such
as alcohol containing free ammonia to prevent discoloration of the products and to
protect metals substantially as described.
3. In the manufacture of ammonium nitrate the recovery of the unconverted
sodium nitrate and ammonium sulphate substantially as described.
Dated this 23rd day of October 1806
THOMAS FAIRLEY.
Boult & Wade,
Agents for the Applicant.
THOMAS FAIRLEY.
Boult & Wade,
Agents for the Applicant.