IMPROVED PROCESSES FOR THE MANUFACTURE OF AMMO- NIACAL SALTS, AND MORE PARTICULARLY THE SULPHATE OF AMMONIA
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by. Alexander Melville Clark at
the Office of the Commissioners of Patents, with his Petition, on
the 22nd May 1875.-A communication from abroad by Théophile
Moerman-Laubuhr, of Antwerp, in the Kingdom of Belgium.
I, ALEXANDER MELVILLE CLARK, of 53, Chancery Lane, in the
County of Middlesex, Patent Agent, do hereby declare the nature of the
said Invention for "IMPROVED PROCESSES FOR THE MANUFACTURE OF AMMO-
NIACAL SALTS, AND MORE PARTICULARLY THE SULPHATE OF AMMONIA," to be
as follows ::—
This Invention relates to improved processes for the manufacture of
ammoniacal salts, and more particularly of sulphate of ammonia, by
means of the nitrogen of the air.
I will proceed to explain the processes as succinctly as possible, with-
out, however, omitting anything which would tend to render the same
clear in all its bearings.
First, as regards the apparatus, I substitute for the iron retorts here-
tofore employed blast furnaces or cupolas on the Fleck system, having

page_text: two openings at the upper part, one a lateral opening for the introduction
at the proper moment either of fuel or of other suitable ingredients or
mixtures. By this means I am enabled if necessary to manufacture the
cyanides and ammonia alternately, but I find it preferable to divide the
manufacture into two or three distinct operations in order to simplify the
work and render it more regular. Thus according to the process of this
Invention I first commence by the manufacture of the alkaline cyanides,
which may be done without difficulty, and in proof of this I may here
simply quote two extracts from the works of well-known chemists,
which are sufficiently conclusive, and also serve to show how these
cyanides have long been made, and how they may without doubt be
produced from the nitrogen of the air (see Regnault, vol. 3, folio 34, on
this subject. Also Cahours, vol. 2, folio 143, under the head of cyanide
of potassium).
'
These quotations suffice to prove that the manufacture of cyanides
may thus be easily effected by means of the nitrogen of the air. The
following is the method which I prefer to adopt for the purpose:-
"
(I.) I first mould and dry blocks composed of two parts of wood,
charcoal, or pulverized coke, and one part of the alkaline salt, which is
to serve as the base of the cyanide. If necessary, to give greater con-
sistency to the blocks, a little clay may also be added, but a brick
machine will make these blocks rapidly after the mixture has been well
kneaded.
(II.) The furnace or cupola for producing the cyanide is fed with
these blocks of fuel. The most suitable' furnace for the purpose is one 2
on the Fleck system used in the manufacture of phosphorus.
(III.) It is advantageous to employ in addition a special cupola or a
coke column in which small coke is burnt, and through which a current
of air is forced by a blower. The coke absorbs the oxygen, forming
carbonic acid, which passes off with the nitrogen isolated or already
partially converted into cyanogen.
:
-(IV.) This burnt air may then if necessary be passed through lime
water to absorb the carbonic acid formed, while the nitrogen purified
and isolated is conducted into the cyanide furnace, where it passes
through the incandescent blocks, composed of charcoal and alkali, above 3
referred to.

page_text: cyanogen
Under the action of the incandescent charcoal stimulated by the blast
and of the intense heat produced (dull red) the radical of the alkali is
reduced, and absorbs the cyanogen to form cyanide. Now the
is simultaneously produced by the combination of the nitrogen with the
carbon. This double reaction thus produces alkaline cyanide, which
runs to the bottom of the furnace, whence it is drawn off every morning
and evening into a pit. As, however, the cyanides always evolve hydro-
cyanic acid (which is a virulent poison) when brought in contact with
air, they are run off through a valve placed near the outlet into an
enclosed pit provided with a chimney, through which the noxious gases
are allowed to escape.
The cyanides after cooling serve for the manufacture of ammonia, as
will be herein-after described.. The alkaline cyanides being all soluble
may all be used for manufacturing cyanides, the more so as they will
serve for an indefinite number of times. It is thus evident that but
little choice need be made as regards economy between one alkali and
another, although I would observe that certain alkalies absorb more
nitrogen or cyanogen than others, and this fact should not be forgotten
in making the selection, as will be shown by the following formulæ :-
The formula of cyanide of potassium is O³ az K
"
"
sodium
is O³ az Na
aalaium
is Car Co
Cz
ン

page_text: carbon does not vary, but is relatively the same in all carbonates and
oxides, the above-mentioned proportion of difference in the amount of
alkali required for fixing the cyanogen remains also proportional in con-
formity with the indications above given.
I will now consider the approximate cost of one hundred thousand
kilogrammes of cyanide of calcium produced in the above manner
according to theoretical calculations.
100 of do.
-
"
do. x
*
46
do..
28 x 100 say, 52 lime to produce theoretically 100 kilogrammes of
cyanide. Hence to produce 100 kilogrammes of cyanide of calcium 2
52 kilogrammes of lime are theoretically required, and as the fuel is
composed of about one-third lime and two-thirds charcoal, in order to
produce 100,000 kilogrammes of cyanide of calcium there is required

page_text: Now 100,000 kilos, cyanide of calcium will theoretically produce in
ammonia as under,—
that is to say, the cyanide of calcium produces in the above reaction
17 of ammonia theoretically; now 82: 17 = 100: x = 20% of ammonia,
thus in 100,000 kilogrammes of cyanide of calcium there are contained
the elements of 20,000 kilogrammes of ammonia. I will further on
explain how this ammonia is extracted from the cyanides, but will first
of all ascertain to what these 20,000 kilogrammes correspond in sulphate.
or hydrochlorate of ammonia.

page_text: :
:
cent of ammonia. Thus it follows that 20,000 kilogrammes of
ammonia correspond to sulphate of ammonia 100: 26 = x 20,000 =
about 76,923 kilogrammes of sulphate of ammonia, such as it is found
in commerce.
say 17 of ammonia for 36,, 46 of hydrochloric acid, but in practice sal
ammoniac often contains like the sulphate 29 per cent. of water in
addition, which is not indicated in its formula; now 53,, 46:17 = 100: x
= 32 per cent. of ammonia, whilst in practice it ordinarily contains but 1
25 per cent, say 17:14 = 25: x = 20 per cent. of nitrogen. Thus
.inasmuch as sal ammoniac contains 25 per cent. of ammonia, it follows
that 20,000 kilogrammes of ammonia correspond to about 80,000 kilo-
grammes of sal ammoniac. The commercial value of sulphate of
ammonia being fcs. 45 per 100 kilogrammes, it follows that 76,923 2
kilogrammes of sulphate of ammonia possess a commercial value of
76,923 × 0.45 = fcs. 34,, 615,, 35. I will further on estimate the value
this may attain in practice. I will next proceed to explain how by this
improved process ammonia is extracted from alkaline cyanides, and also
how the nitrogen of the cyanides is converted into ammonia, but in
order to render the explanation clearer I will describe the same in
accordance with known principles.
1ST. METHOD.
By the dissolution, boiling, and prolonged distillation in water of the

page_text: several chemists. For example, Pelonze says in the "Annales de
Chimie," vol. XLIII., page 396, that by a prolonged boiling in a
close vessel at a high temperature, and distillation in iron boilers
alkaline cyanides dissolved in water are decomposed and converted into
1 atom of alkaline formiate and 1 atom of ammonia, by reason that by
the boiling in water the alkaline cyanide is decomposed, and at same
time decomposes 4 atoms of water which it takes up. The effect of this
double decomposition and reduction is to produce the reaction above
explained. This reaction is also indicated by various other authors, for
instance in Wurtz' Dictionnaire de Chimie, page 1123, as well as in
Baruel, vol. 2, page 64, in H. Rose's Complete Treatise on Qualitative
Analysis, page 728, in Pelonzo and Frémy, volume 2, page 30, and
volume 3, folio 35, as also in Thénard, edition 1836, volume 2, folio 86...
The references above given are sufficient to prove that in principle
this mode of operating is essentially practical, but in order to ensure
success attention should be paid to the following points :-(A) the
decomposition of the cyanides when distilled in water in a close vessel
takes place slowly, and the consequence is that much of the water is
carried off in the form of vapor with the ammonia that is evolved,
whereas to avoid all unnecessary delay in distilling, the ammonia should
as much as possible pass off alone. To this end the distilled ammonia
should be passed into a worm having a large number of turns and of
considerable height in order to obtain a lengthened traverse. This coil
should be placed within a large tube of the same height containing cold
water, which is kept constantly renewed by a descending current for the
purpose of keeping the coil constantly cooled and of condensing the
steam carried into the worm along with the distilled ammonia. In this
manner the ammonia is separated in a great measure from the stoam
carried off therewith. The water of condensation is continually returned
to the boiler, while ammonia only is conveyed into the next apparatus
in order to avoid the necessity of distilling it over again (B).
In decomposing cyanides a small quantity of hydrocyanic or prussic
acid is invariably formed. This may however be avoided by adding to
the cyanide 25 per cent. of oxide of the same base as the cyanide, and
afterwards passing the ammonia produced through a bath of potash,
soda, or lime, dissolved in water in which it is washed and deprived of

page_text: The operation thus modified and improved differs entirely in its form
and results from all practical attempts hitherto made in this direction
(see Wagner, volume 1, folio 409).
4TH METHOD.
It is possible, although not advisable, to directly decompose in
concentrated acids in excess the cyanides or the alkaline cyanates
manufactured in the manner above described as the second method of
operation, for by reacting on these cyanides or cyantes with powerful
acids, such as sulphuric or hydrochloric acid in excess the following
reaction is produced :—
KO, az* C*0 + 280° + 3 HO = 80³, KO + SO³ az H² + 400,
1 atom of cyanate, with
that is to say,
."
2 atoms of acid, and
3 atoms of water are decomposed, and form
1 atom of basic sulphate,
"
1 atom of sulphate of ammonia,
4 atoms of carbonic acid, which are evolved.
There only remains to separate the sulphate of ammonia formed with
the basic sulphate, and to evaporate and crystallize it. This would be
perfect if it were not that besides this reaction there is always simul- :
taneously formed a considerable amount of prussic acid, which in too
great quantity is highly objectionable. Thus ammonia might also be
extracted from the cyanides by means of acids, although only in an
indirect way, which presents many objections; for with hydrochloric
acid in excess crystals of salammoniac are formed, but at the same time?
there is also a large evolution of prussic acid (a most virulent poison),
which it is true can be collected and neutralized in an alkaline liquid
and caustic bath, but nevertheless the evolution of prussic acid is far
from being desirable (see Dictionnaire de Chimie de Wurtz, page 1123,
and Thénard, 1836 edition, vol. 2, page 86). It should be remarked that
the reaction differs according to the amount of hydrochloric acid added
to the water in which the cyanide is dissolved.
When there is. but little acid the following is the reaction :-
Caz K+ HCl = KCl + C²-az H.

page_text: In practice this method is very complex and inexact, otherwise it
would only be necessary to separate and then to distil this double
sulphate of ammonia formed with chalk or lime in order to evolve either
carbonate of ammonia or ammonia according as chalk or lime is
employed. In any case the cyanides when treated with sulphuric 5
acid always evolve such an amount of prussic or hydrocyanic acid (as is
confirmed by Regnault, volume 2, page 93) that as before mentioned this
method is both dangerous and impracticable.
Of the four different methods before described for extracting ammonia
from cyanides either one may be selected, as preferred. The three first 1
are however the most rational, and each offers its own peculiar advan-
tages. Practical experience alone will show which is the best of the
three. There is neither difficulty nor inconvenience in alternately trying
all three in practice, and while I prefer the first method I am convinced
that the second and third methods will give satisfactory results, they 1
being regular and easy of execution.