PROCESS AND APPARATUS FOR THE MANUFACTURE OF SODA BY THE AMMONIA TREATMENT
Year: 1884

page_text: TALLIBLOO
SPECIFICATION,
I, JOHN IMRAY of N° 28 Southampton Buildings Chancery Lane in the County
of Middlesex, Consulting Engineer and Patent Agent do hereby declare the nature
of the said Invention for "PROCESS AND APPARATUS FOR THE MANUFACTURE OF
SODA BY THE AMMONIA TREATMENT" and in what manner 'the same is to be
performed, to be particularly described and ascertained in and by the following
statement, that is to say :-
-
In the Specification to Letters Patent dated the 14th October 1881 N° 4491 was
described a process for the manufacture. of soda by ammonia treatment, according
to which is effected the combination of carbonic acid and highly hydrated ammonia
in the gaseous condition, in which condition the surfaces of contact are largely
extended and consequently the carbonation is rapid and complete. The apparatus
employed for this process, as described in the Specification above referred to,
consisted of a series of horizontal cylinders with operating vessels above them, each
of these cylinders being charged to about two thirds of its capacity with the
ammoniacal liquor, through which carbonic acid was blown by central perforated
tubes. In this process there, is not only a combination of carbonic acid with
ammonia in the liquid, there is also a large quantity of ammonia mechanically
separated from the liquid, and this, in the gaseous condition, combines with the
excess of carbonic acid in the upper part of the cylinder forming bicarbonate of
ammonia in a state of minute subdivision, which falls back into the liquid and
reacts on the sodium chloride solution.
The present Invention relates to an arrangement of apparatus and method of
conducting the process whereby the reactions are produced and applied under
improved conditions.
Fig. 1 of the accompanying Drawings is an elevation and Fig. 2 is a plan shewing
the arrangement of the apparatus. A number of cylindrical vessels A are arranged
in a slope, each having a central perforated tube a, to which a branch c leads from
the vessel next below it. The central tube a is the hollow axis of an agitator
which is kept in motion to prevent deposit of bi-carbonate. Each vessel has an
overflow pipe leading to nearly the bottom of the next lower vessel. Above the

page_text: highest vessel is an ammonia condenser D filled with salt water and supplied with
ammonia by pipes d; and above the level of the condenser D is placed a washing
vessel E. This vessel E, being supplied continuously with saturated solution of
salt, the overflow passes by the pipe e¹ into the condenser D, becomes there charged
with ammonia, and passes by the overflow pipe d¹ to the uppermost vessel A and
thence from vessel to vessel downwards to the last at B. Meanwhile carbonic
acid is supplied by the pipe M to the lowest vessel, whence a portion passes
upwards from vessel to vessel by the pipes c and a, until the excess flows by the
pipe N into E where it is freed from the last traces of ammonia carried with it.
Any ammonia that may escape from D passes by the pipe N into E where it is
retained in the solution. Thus the salt solution supplied to E and there receiving
a small supply of ammonia passes into D where it becomes ricbly charged with
ammonia, and thence through the series of vessels A, becoming carbonated more
and more as it descends, there being thus collected continuously in the lowest
vessel B a magma of bi-carbonate of soda which can be removed from time to time
or continuously. Additional salt may be supplied to the liquor by a funnel R.
Instead of leading the carbonic acid from vessel to vessel, each may have its own
separate supply by its perforated pipe a governed by a cock or valve.
The bi-carbonate of soda withdrawn from the lowest vessel B may be calcined
in the usual way, or it may be transformed into soda salt or mono-carbonate in the
following manner. The magma along with pure water is introduced into a closed
vessel and being heated for several hours, it gives off ammonia and carbonic acid
which are collected for subsequent use, and becomes ultimately a clear solution of
carbonate of soda containing a small proportion of bicarbonate in solution. This
liquor being decanted and mixed with a little slaked lime, gives, after a brief period
of settlement, a very pure solution of carbonate of soda at about 33° Beaumé.
This may be left to crystallise producing good crystals, or it may be concentrated
by evaporation in shallow vessels arranged in descending order and heated by the
waste heat of the factory fires or otherwise. The soda thus obtained is of
remarkable purity, and can be readily quite de-hydrated by heating in open
vessels. The process also presents the great advantage of avoiding calcination of
the bicarbonate, which is long and troublesome because the bicarbonate is a very bad
conductor of heat.
Having thus described the nature of this invention and in what manner the
same is to be performed as communicated to me by my foreign correspondents,
I claim :-
1. The herein described process for manufacture of soda by treating salt solution
with ammonia, and carbonating in successive vessels.
2. The herein described arrangement of apparatus whereby the process is
rendered continuous.