Improvements in the Manufacture of Carbonate of Soda by Aid of Ammonia.
Year: 1885

page_text: Improvements in the Manufacture of Carbonate of Soda by Aid
of Ammonia.
I JEAN JAQUES THIOPHILE SCHLOESING of 67 Quai D'Orsay in the City of
Paris France Chemist, do hereby declare the nature of my invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF CARBONATE OF SODA BY AID OF AMMONIA
to be as follows:-
"
At the present time in the manufacture of, Carbonate of Soda, Crystals of
Bi-carbonate of Ammonia are thrown into a solution of Salt (brine) where they are
maintained in movement and where the reaction between the Bicarbonate of
Ammonia and the Chloride of Sodium takes place, so that two thirds of the Salt or
thereabouts are converted into Bicarbonate of Soda and the Bicarbonate of
Ammonia becomes Chloride of Ammonia as described in the Specification of a
Patent granted to Sydney Pitt N° 2130 in the year 1878, a Communication made
to him from abroad by me.
According to my present invention I proceed as follows:-
Into a tub which is provided with a convenient method for filtering the liquors
such for example as a grating placed across the lower part of the tub and covered
with cloth or other convenient arrangement and which is also provided with an
outlet at the bottom I run a certain quantity of the mother liquor coming from a
preceding operation-I then add the crystals of Bi-carbonate Ammonia taking care
to cause them to settle down in a solid mass so that there shall be no lumps nor
any confined air-Having filled the tub I allow the mother liquor to run out by
the hole at the bottom which has hitherto been stopped and then by a properly
devised arrangement I spread in a perfectly regular and even manner a solution of
Common salt (brine) over the mass-The brine passes through the Bicarbonate
Ammonia and the transformation of that salt into Bicarbonate Soda takes place on
the one hand while on the other a solution of Chloride of Ammonia is formed―
The resulting solution is run out from the bottom and an examination of it shows
when the operation is complete.
There remains a mass of Bi-carbonate of Soda which is washed with water by
the same apparatus as is used for distributing the brine-The washing may be

page_text: methodic in character, i.e. the washing water from one such tub may be used in the
next When the washing is complete which is shewn by the absence of Ammonia
in the liquid running out from the bottom of the tub the inflow of water is stopped
and the contents of the tub are allowed to drain-There ultimately results a mass
of Bi-carbonate of Soda which is sufficiently coherent to be removed in fragments
and this is calcined for the purpose of driving off the extra Carbonic acid and the
moisture From the physical condition of the mass the gas of combustion from
the torrefying furnace can pass directly through it and thus there is obtained
considerable economy of fuel.
By this process a Carbonate of Soda is ultimately obtained of a much denser
character than that usually produced by the Ammonia process.
1007

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Carbonate of Soda by Aid
of Ammonia.
I, JEAN JAQUES THEOPHILE SCHLOESING of 67 Quai d'Orsay in the City of
Paris France 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:-
At the present time in the manufacture of carbonate of soda by my process as
described in the specification of a Patent granted to Sydney Pitt N° 2130 in the
year 1878 a communication made to him from abroad by me crystals of bi-carbonate
of ammonia are thrown into a solution of salt (brine) where they are maintained in
movement and where the reaction between the bi-carbonate of ammonia and the
chloride of sodium takes place so that two thirds of the salt or thereabouts are
converted into bi-carbonate of soda and the bi-carbonate of ammonia becomes.
chloride of ammonium.
According to my present invention I proceed as follows.
Into a tub which is provided with a convenient method for filtering the liquors
such for example as a grating placed across the lower part of the tub and covered
with cloth or other convenient arrangement and which is also provided with an
outlet at the bottom I run a certain quantity of the mother liquor coming from a
preceding operation. I then add the crystals of bi-carbonate ammonia taking care
to cause them to settle down in a solid mass so that there shall be no lumps nor
any confined air. Or preferably I run in the magma consisting of mother liquor
and bi-carbonate of ammonia without previous separation or further treatment.
Whilst filling the tub I allow the mother liquor to run out by the hole at the
bottom.
When the tub is filled then by a properly devised arrangement I spread in a
perfectly regular and even manner a solution of common salt (brine) over the mass.
The brine passes through the bi-carbonate ammonia and the transformation of that
salt into bi-carbonate soda takes place on the one hand while on the other a
solution of chloride of ammonium is formed. The resulting solution is run out
from the bottom and an examination of it shows when the operation is complete.
There remains a mass of bi-carbonate of soda which is washed with water by the
same apparatus as is used for distributing the brine.
The washing may be methodic in character i.e. the washing water from one such
tub may be used in the next. When the washing is complete, which is shown by
the absence of ammonia in the liquid running out from the bottom of the tub, the
inflow of water is stopped, and the contents of the tub are allowed to drain.
There ultimately results a mass of bi-carbonate of soda which is sufficiently
coherent to be removed in fragments, and this is calcined for the purpose of
driving off the extra carbonic acid and the moisture. By this process a carbonate

page_text: of soda is ultimately obtained of a much denser character than that usually
produced by the ammonia process.
In order that my said invention may be fully understood I will describe more in
detail with the aid of the annexed drawings the manner in which I prefer to
operate.
Figure 1 is an end elevation partly in section of the series of tubs or vessels
which I employ and apparatus in connection with the same. Figure 2 is a side
elevation of one of the said tubs or vessels with other apparatus.
A A are the tubs the number may be varied but ten tubs form a very suitable
and convenient set. The tubs can be connected in pairs any tub of the set being
coupled with any other by opening valves on the pipe B with which all the tubs
communicate near their upper ends.
Each tub is provided at the bottom with a central orifice into which a plug
bearing a wooden post C is inserted before the operation begins.
It is also provided with a second hole D at one side of the bottom communicating
with a box É divided into four compartments.
By means of an india rubber tube the liquids issuing from the bottom of the
vessel can be diverted into any of these compartiments.
On the bottom of the tube is placed a grating of wood or iron covered with a
proper filtering cloth the cloth itself being if necessary protected by another
grating.
The tub is closed at the top with a light and moveable cover having a central
hole which by a flexible pipe is put in communication with a cast iron box G
suspended above the tubs. Into this box the various liquids can be directed from
a second box K placed at a higher level. The tub being thus ready for use the
magma of bi-carbonate of ammonia from the cooling tubs which receive it from the
bi-carbonising operation is made to run into it.
In order to ensure a regular deposition of the crystals the post C is provided
with a cone at its upper part on to which the magma entering the tub is directed;
the stream having been first broken by a circular plate attached to the cover. The
crystals are separated by filtration from the mother liquor which passes out of the
tub and is made to flow into the pipe marked H. Through this pipe it is returned
to the process and again treated in the production of a further quantity of
bicarbonate of ammonia.
Should the filtration not be sufficiently rapid to empty the tub of mother liquor
the surplus bearing with it a certain quantity of crystals passes by the pipe B and
connections into the tub A which is next to be filled. In this way all risk of
crystals returning to the process is avoided.
The tub having been filled to a convenient depth with crystals of bi-carbonate of
aminonia which is ascertained by probing the advent of the magma is stopped the
cover is removed and in its place is put an apparatus by means of which the liquids
for the treatment of the bi-carbonate of ammonia can be applied with great
uniformity. The apparatus which it is preferred to employ is a circular or annular
tray L with a bottom cut in a spiral form as represented by Figure 3 the shape of the
spiral being determined by the formula σ = √ √ where r is the radius of
the tray a the angle and σ the successive values of the radius vector corresponding
to those of a.
This tray is supported on the edge of the tub by rollers and is pro-
vided with a central boss through which passes a shaft which rests on the top of
the central post C and continued upwards bears a sheave.
2 7
On the shaft beneath this sheave is placed a sleeve carrying at its upper end a
second sheave and beneath that a cup shaped vessel having a sufficient number of
pipes (4 to 8) issuing from its bottom and extending to the outer rim of the spiral
shaped tray above referred to.
The arrangement of boxes already described permits brine to be admitted into
the cup and thence along the pipes to be delivered on to the margin of the tray.

page_text: The cup and its pipes which are made of iron are caused to rotate slowly in one
direction while the tray turns in the opposite sense.
The brine flows inwards in
consequence of the inclination of the surface of the tray until it reaches the spiral
edge from which it falls in drops on to successive portions of the surface of the
crystals and so is distributed over this surface with great uniformity.
The brine passes through the crystals of bicarbonate of ammonia and in doing so0
forms bi-carbonate of soda which remains in the tub and chloride of ammonium in
solution which passes out through the smaller orifice D in the bottom above
referred to and thence returns to the process and is treated for the reproduction of
ammonia.
After a certain lapse of time the decomposition approaches completion which
is shown by the augmentation in the specific gravity of the liquid issuing from
the tub.
This is then diverted into another receptacle and is used at the beginning of the
succeeding operation.
When the liquor issuing from the tub attains nearly its maximum density the
advent of brine is stopped and in place of it water is made to run on to the tray.
The first portion of the washing water, which contains a large quantity of
chloride of ammonium is returned to the process while the second is used for
washing the contents of the succeeding tub.
No pause takes place between the successive operations above described. The
crystals of bi-carbonate of ammonia when deposited in the tub are moist with the
mother liquor; the brine in arriving drives this before it and leaves a mass of
bi-carbonate of soda moistened in its turn by chloride of ammonium.
The first washing water drives this out and the second washing water finally
removes all but a trace of ammonia from the mass and leaves the operation
completed.
The tub is allowed to drain until the surplus moisture runs away.
If deemed advisable an aspirator may be employed to hasten this operation.
As soon as this is complete the revolving tray is removed and for facilitating
this it is suspended from a carriage travelling on an overhead railway. The
central post C is now removed and the contents of the tub emptied through the
hole thus remaining.
The resulting bi-carbonate of soda is treated in any convenient furnace in order
to expel the moisture the excess of carbonic acid and any ammonia which may
remain.
The supply box K has five connections k¹³ ³ k and k³; of these the first k¹
brings the bi-carbonate of ammonia magma to the apparatus, 2 brings pure water
for washing, water which has been already used in washing, k brings fresh brine
and brine which has been already used. By means of the flexible pipe con-
nections represented in the drawings any of these liquids can be supplied to any
compartment of the supply box G and these compartments are connected when
required by flexible pipes with the tubs A.
The exit box E has four compartments or troughs and a flexible pipe connected
with D can be shifted from one to the other as may be required.
One of the compartments is connected with the pipe H which receives the mother
liquor; another with a pipe e¹ which receives the washing water and from which
it is pumped up for re-use; a third with a pipe e which receives the chloride of
ammonium from which ammonia is to be recovered and a fourth e³ the strong
brine to be pumped up for re-use.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what
I claim is
(1). The method for the conversion of bi-carbonate of ammonia into bi-carbonate
of soda consisting in introducing the bicarbonate of ammonia together with mother

page_text: liquor into a filtering tub or vessel, drawing off the mother liquid and then
admitting brine to percolate through the mass of bi-carbonate of ammonia sub-
stantially as described.
(2). The arrangement of apparatus substantially as described for conducting the
said process in.a continuous and methodic manner.