Improvements in the Manufacture of Ammonium Nitrate and other Salts.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Ammonium Nitrate and other
Salts.
I, WILLIAM GARROWAY, Netherfield Chemical Works, Duke Street, Glasgow,
Chemical Manufacturer, do hereby declare the nature of this invention to be as
follows:-
My invention relates to a continuous and improved process for the manufacture
of ammonium nitrate, and it has also for its object the manufacture of silicate of
soda and of potash and caustic soda or potash.
For this purpose I take nitrate of soda or of potash with sand or ground flint
and heat them in a suitable mechanical retort through which I pass superheated
steam and hot air, silicate of the alkaline base is formed while nitric acid is evolved.
The nitric acid vapours given off from the mixture in the retort or vessel is led
through earthenware pipes into stoneware towers, where it meets an ascending
current of ammonia gas, where the combination of the two gases at once takes place,
and the solution of the ammonium nitrate thus formed is drawn off, and evaporated
to obtain the solid salt.
The ammonia for the process may be obtained from the gas liquors of iron works
or from any other known source.
In the process of decomposing the nitrate of soda with sand and steam a small
quantity of nitric oxide may be formed, which can be conveniently condensed in a
Cay-Lussac coke tower or it may be converted back to nitric acid by admission of
hot air and steam.
Th 17th If Yamah 1007
Improvements in the Manufacture of Ammonium Nitrate and other
Salts.
I, WILLIAM GARROWAY, of Netherfield Chemical Works, Duke Street, Glasgow,
Chemical Manufacturer, 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:-
This invention relates to improvements in the manufacture of silicate of sodium
and potassium and of nitric acid and ammonium nitrate, and it has also for its
object the manufacture of caustic soda and caustic potash, in a cheap and efficient
manner, and without the use of any expensive reagent or material.

page_text: For this purpose I mix nitrate of soda or of potash with silica in the form of sand
or ground flint and heat them in a suitable furnace or mechanical retort, over which
and through which I pass superheated steam and hot air, silicate of the alkaline
base is formed, while nitric acid is evolved and may be condensed by any known
means for the manufacture of nitrate of ammonia or lead nitrate in the process for
producing lead carbonate from the basic nitrate with ammonia and carbonic acid.
When the action has ceased the silicate of soda or of potash that remains in the
furnace is withdrawn, and may either be disposed of directly for glass making or
treated with water and steam, some of the sand or silica remains insoluble, but the
silicate of soda or potash dissolves and forms a solution, which after being boiled
down or concentrated to the desired strength, may be employed for the manufacture
of soap, or in the process of mineral oil rectifying etc. etc. or the silicate of soda or
potash may be treated with lime, to precipitate the silica, while the caustic soda
or potash remains in solution and may be treated by any known means, and the
insoluble silicate of lime be dried and treated for the manufacture of cement or
artificial stone etc.
In carrying out my invention I proceed as follows:-
I mix together from one hundred to one hundred and fifty parts by weight or
thereabout. of nitrate of soda or its equivalent of nitrate of potash, with one hun-
dred parts by weight of sand or ground flint, and place this mixture in a suitable
furnace or mechanical retort, heated to the required temperature, I then pass super-
heated steam through the hot charge (in a manner analogous to that which I
have described in my Specification No. 2489 A.D. 1896).
I operate in such a way as to make the process a continuous one or nearly so.
The nitric acid evolved from the heated mixture in the furnace, I lead by earthen-
ware pipes, (at some point of which is interposed a condenser in order to recover the
more condensible portion of the nitric acid) into towers properly packed with
baffling material, and through which there passes a continuous current of ammonia
gas or ammonia vapours produced by the distillation of ammoniacal liquors of blast
furnaces, gas works, shale distillation works, gas producers, and the like.
The nitric acid gas and the ammonia vapours combine together in the towers,
to form the nitrate of ammonia, which is immediately condensed, forming a solu-
tion, which is run off by a tap at the bottom of the towers and is carefully evapor-
ated in enamelled cast iron pans to obtain the solid nitrate of ammonia; any nitric
acid, ammonia or nitrate of ammonia vapours which may escape condensation in
the towers, I fix by conveying them through a final tower, and when I work with
an excess of ammonia gas, as is sometimes desirable I provide a downflow of sul-
phuric acid in this tower in order to fix all the ammonia, producing sulphate of
ammonia, which may be boiled down or concentrated by any known means.
Or the nitric acid evolved in the process hereinbefore described, may be con-
densed, in any well known manner, and the nitrate of ammonia prepared by adding
a solution of ammonia (obtained from the ammoniacal liquors of gas works, blast
furnaces, and the like) until neutralisation has been reached, when the solution is
concentrated to obtain the solid ammonium nitrate.
In carrying out my invention I do not confine myself to the exact proportions
of the ingredients stated. I find that while the reactions take place within wide
limits, the proportions stated are very suitable for the process.
It will thus be seen that my process for the production of nitric acid, and nitrate
of ammonia have great advantages over the processes hitherto in use.
For example in making caustic soda or potash, by the ordinary process known
as the "Le-blanc" process, at least four stages or steps are necessary-(1) The
preparation of the alkaline sulphate by the action of sulphuric acid on the nitrate,
(2) the roasting of the acid sulphate of soda with chloride of sodium, (3) the pro-
duction of alkaline carbonate by furnacing the sulphate with coal and limestone,
(4) the causticising of the carbonate by means of lime.
There is also a large amount of alkali waste produced which is a disadvantage.
My improved process, however, is accomplished in two operations, without producing
any waste material. Again, in the manufacture of caustic soda from carbonate of

page_text: soda produced in the wellknown "ammonia soda "
sary:-
process, four steps are also neces-
(1) The formation of bi-carbonate of soda by acting on common salt with am-
monia and carbonic acid, (2) the production of the carbonate of soda from the bi-
carbonate by heating, (3) the causticising of the carbonate so obtained and (4)
the recovery of the ammonia by treatment with lime, in which process a large
amount of chloride of calcium, a waste product, is produced and has to be dealt with.
The apparatus and plant I employ, when my process is connected with the manu-
facture of nitrate of ammonia, will be readily understood from the accompanying
drawings and the following description.
Figure 1 is a muffle furnace with cast iron hearth, where the heat from the fire A,
and superheated steam, complete the decomposition of the nitrate of soda and sand,
into sodium silicate and nitric acid.
B is a hopper by which the mixed materials are introduced into the furnace in
proper quantities-C, a steam pipe, D door by means of which the charge can be
raked and shifted-E, drawing off or discharging door-F, stoneware pipe leading
the nitric acid gas from the furnace shewn in cross section Fig. 2 to condenser G
where it is partially cooled (and the most condensible portion of the nitric acid thus
obtained, may be used up for neutralising any excess of ammonia found in the
condensed liquors from the earthenware towers-(Fig. 4) or the acid may be em-
ployed for the manufacture of lead nitrate or nitrated phosphates may be
prepared by it for use as a manure) Figure 4, side elevation of stoneware con-
densers. H circular opening where pipe enters for conveying the ammonia vapours,
produced by the distillation of the ammoniacal liquors. Figure 5, Glover's tower
with distributing apparatus to regulate the flow of sulphuric acid that may be
required to fix any ammonia, which may escape condensation in the earthenware
towers.
Figure 3 represents longitudinal section of mechanical retort showing shaft E
that revolves with arms or discs at a regulated speed.
Though the hopper 13, the mixed materials are introduced and carried by the
arms to the door H, and the discharge should be continuous or nearly so. C, is
the super heated steam supply pipe.
D, the fire place and flues.
O the pipes leading gas to condensers or stone towers.
Figure 3 is cross section of same showing fire place and pipe O^ leading the
nitric acid to condensing towers.
Having now particularly described and ascertained the nature of my said in-
vention, and in what manner the same is to be performed, I declare that what I
claim is:-
1. The production of silicate of soda and of potash and nitric acid by heating
a mixture of silica in the form of sand or ground flint, with nitrate of soda or of
potash with superheated steam as hereinbefore described.
2. The production of caustic soda or caustic potash by treating the silicate of
soda or of potash obtained in the aforesaid process, with lime, as hereinbefore
described,
3. The process for producing nitrate of ammonia by heating a mixture of silica,
in the form of sand or ground flint, with nitrate of soda or of potash, with super-
heated steam as in the aforesaid process, and condensing the nitric acid gas, pro-
duced in suitable towers with ammonia vapours, produced by the distillation of the
ammoniacal liquors of blast furnaces, gas works, and the like, in a manner substan-
tially as hereinbefore described.
Tad the 17th J... Daramba 1907
JOHNSONS,
Applicant's Agents, 115, St. Vincent Street, Glasgow.