Improvements in the Manufacture of Ammonium Nitrate.
Year: 1899

page_text: Date of Application, 13th May, 1899
Complete Specification Left, 13th Feb., 1900-Accepted, 12th May, 1900
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Ammonium Nitrate.
I, JOSIAH WYCKLIFFE KYNASTON, of Oak Terrace, Beech Street, Liverpool, in the
County of Lancaster, Analytical Chemist, do hereby declare the nature of this
invention to be as follows:-
The usual mode of manufacture of ammonium nitrate is by neutralising nitric acid
with liquid or gaseous ammonia or by ammonium carbonate, and it involves the prior
production of nitric acid on the one hand and on the other the distillation of some
ammonium salt with lime or its carbonate to produce aminonia or ammonium carbonate.
Various proposals have from time to time been made to produce ammonium nitrate
by the mutual decomposition of sodium nitrate and ammonium sulphate, but so far
no process of this kind has been commercially successful principally because of the
extreme solubility of ammonium nitrate which makes it practically impossible to free
it of other salts even by repeated recrystallisation.
My improvements in this manufacture enable me to produce ammonium nitrate of
great purity from sodium nitrate and ammonium sulphate.
When a solution of sodium nitrate is mixed with a solution of calcium chloride, the
two salts being present in exactly equivalent quantities, and the mixed solution is.
boiled down, sodium chloride falls out, being insoluble in the hot liquors and calcium
nitrate remains in solution. In this way 80 to 85 per cent. of the sodium present can
be removed from solution, but for the reason that calcium nitrate even in highly
concentrated solution obstinately refuses to crystallise, no further separation of sodium
chloride can be effected. The addition of three or four times the bulk of alcohol in
which sodium chloride is insoluble, fails to cause separation of any material quantity
of this salt.
When a solution of sodium nitrate and strontium chloride, in which the salts are
present in exactly equivalent quantities, is boiled down, a large proportion of the
sodium present separates as sodium chloride, whilst an equivalent quantity of strontium
nitrate remains in solution, and if this solution, whilst still hot, be drawn off the
deposited sodium chloride, it yields, on cooling, crystals of strontium nitrate. Or, if
the solution, from which by concentration as above, the greater part of the sodium
chloride has been separated and removed, be still further concentrated, anhydrous
crystals of strontium nitrate mixed with a small proportion of sodium chloride are
deposited. By repeated treatment on the lines as above or by recrystallisation, there
is ultimately produced a pure or almost pure strontium nitrate and a perfect or almost
perfect separation of the sodium as chloride.
I make use of the above reaction represented by the equation 2 NaNO, + SrCl₂
Sr (NO3)2 + 2 Na Cl as the first stage in the manufacture of ammonium nitrate.
=
To a solution of the pure strontium nitrate thus obtained, I add a solution of
ordinary commercial ammonium sulphate containing that salt in quantity exactly
equivalent to the strontium nitrate present. The reaction which ensues is represented
by the equation

page_text: .
The insoluble strontium carbonate after being well washed is dissolved in
hydrochloric acid to neutralisation, when strontium chloride is obtained ready for
the treatment of a further batch of sodium nitrate as before described.
The solution of sodium sulphate boiled up to the necessary concentration yields on
cooling crystals of Glauber salt or if boiled down to dryness and calcined yields
sodium sulphate.or salt cake of high purity.
Dated this 12th day of May 1899.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicant.
Improvements in the Manufacture of Ammonium Nitrate.
I, JOSIAH WYCKLIFFE KYNASTON, of Oak Terrace, Beech Street, Liverpool, in the
County of Lancaster, Analytical Chemist, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
The usual mode of manufacture of ammonium nitrate is by neutralising nitric
acid with liquid or gaseous ammonia or by ammonium carbonate. This process in-
volves the prior production of nitric acid on the one hand and on the other the dis-
tillation of some ammonium salt with lime or its carbonate to produce ammonia or
ammonium carbonate.
Various schemes have from time to time been proposed to produce ammonium
nitrate by the mutual decomposition of sodium nitrate and ammonium sulphate, but
so far no process of this kind has been commercially successful, principally because of
the extreme solubility of ammonium nitrate which makes it practically impossible to
free it from other salts even by repeated crystallisation.
My improvements in this manufacture enable me to produce ammonium nitrate of
great purity from sodium nitrate and ammonium sulphate.
When a solution of sodium nitrate is mixed with a solution of calcium chloride, the
two salts being present in exactly equivalent quantities and the mixed solution is
boiled down, sodium chloride falls out, being less soluble in the hot liquor than
calcium nitrate. In this way 80% to 85% of the sodium present can be removed
from the solution. As however calcium nitrate even in highly concentrated solution
obstinately refuses to crystallise, no further separation of sodium chloride can be
effected. The addition of three or four times the bulk of alcohol fails to cause
separation of any material quantity of sodium chloride.
When a solution of sodium nitrate and strontium chloride in which the salts are
present in exactly equivalent quantities is boiled down, a large proportion of the
sodium present separates as sodium chloride while the equivalent quantity of
strontium nitrate remains in solution, and if this solution while still hot be drawn

page_text: off from the deposited sodium chloride it yields on cooling crystals of strontium
nitrate, or if the solution from which by concentration as above, the greater part of
the sodium chloride has been separated and removed, be still further concentrated,
anhydrous crystals of strontium nitrate mixed with a small proportion of sodium
chloride are deposited. By repeated treatment on the lines as above, or by recrystal.
lisation, there is ultimately produced a pure or almost pure strontium nitrate and a
perfect or almost perfect separation of the sodium as chloride.
I make use of the above reaction represented by the equation 2 NaNO3 + SrCl2:
Sr(NO3)2 + 2 NaCl as the first stage in the manufacture of ammonium nitrate.
=
The mode of procedure which I have found most convenient and to give the most
satisfactory results is to concentrate the mixed solutions by evaporation until the
proportion of chloride to nitrate in the supernatant liquor remains fairly constant on
repeated trial. The hot liquor is now allowed to remain at rest for a short period,
when any suspended sodium chloride falls out, and the liquor is then drawn off and
set aside to cool when a large crystallization of crude strontium nitrate will result.
The deposited sodium chloride may then either. be removed and washed with hot
water to free it from other adhering salts, or when it has sufficiently accumulated,
the deposit may be dissolved in water, and the solution be again boiled down until
most of the sodium chloride has again fallen out. In either case, the sodium chloride
obtained is now practically free from strontium salts.
The impure crystals of strontium nitrate obtained as above described will consist,
when dried, of from 85 to 90 per cent. of real strontium nitrate and 10 to 15 per cent.
of other salts in admixture. The further purification of these first crystals is effected
by dissolving the crystals in water and concentrating the solution by evaporation,
when strontium nitrate falls out in anhydrous crystalline grains of a high degree of
purity. If the strontium nitrate be required to be of perfect purity, this process is
repeated, when the desired result is attained.
To a solution of the pure strontium nitrate thus obtained, I add a solution of
ordinary commercial ammonium sulphate containing that salt in quantity exactly
equivalent to the strontium nitrate present. The reaction which ensues is represented
by the equation

page_text: from the sodium chloride as described and adding to a solution of the strontium
nitrate, a solution of ammonium sulphate in equivalent proportions.
2. The cycle of operations in the manufacture of ammonium nitrate as set forth by
the following equations--