IMPROVEMENTS IN THE MANU- FACTURE OF CARBONATE OF SODA AND IN APPARATUS EMPLOYED THEREIN
Year: 1882

page_text: LETTERS PATENT to Charles Wigg of Liverpool in the County of Lancaster
Alkali Manufacturer for an Invention of IMPROVEMENTS IN THE MANU-
FACTURE OF CARBONATE OF SODA AND IN APPARATUS EMPLOYED THEREIN
PROVISIONAL SPECIFICATION left by the said Charles Wigg at the Office
of the Commissioners of Patents on the 3rd July 1882,
CHARLES WIGG of Liverpool in the County of Lancaster; Alkali Manufacturer.
"IMPROVEMENTS IN THE MANUFACTURE OF CARBONATE OF SODA AND IN APPARATUS
EMPLOYED THEREIN
"
This relates to the manufacture of carbonate of soda by the ammonia process,
that is to say the process in which free ammonia and carbonic acid gas re-act upon
brine; and the main objects are, to perfect the manufacture and provide improved
apparatus.
Under the first part. In order to precipitate any magnesium compounds contained
in the brine to be treated I add to the said brine a soluble compound of arsenic
such as arseniate of soda and I cause the unabsorbed gases from the saturators or
absorbers or the gases resulting from the roasting of the bi-carbonate of soda, to
pass through in contact with the said brine. The arseniate is added in quantity
sufficient to precipitate the magnesium compounds and the precipitate is roasted
to recover the arsenic and ammonia it contains.
Under the second part. In order to ensure the equal destribution of the ammonia
and carbonic acid gases throughout the brine in the saturators or absorbers I
admit the said gases under say 30 to 40 pounds pressure into the brine through
perforated arms or beaters rotating around a horizontal or vertical axis.
Third. In order to ensure thorough saturation of the brine or absorbtion of the
gases I employ a series of saturators or absorbers in which the gases to be absorbed
are distributed through the brine in the manner setforth under the second part
and cause the said gases to flow from one saturator or absorber to another.
Fourth. I maintain the brine during the reactions which take place in the
saturators or absorbers at the required temperature by means of a cold or
Paine 1

page_text: refrigerating fluid preferably brine which is caused to flow through hollow arins or
beaters caused to rotate around an axis disposed in any suitable plane.
Fifth. Apparatus for carrying my invention into practice consists of cast iron
saturators or absorbers (by preference standing upright) provided with hollow arms
or beaters rotating around horizontal or vertical axes. The upper rotating arms
or beaters are connected with refrigerating fluid inlet and outlet pipes and the
lower arms or beaters are perforated and connected to the ammonia and carbonic
acid gas supply pipes. Gearing is employed for communicating motion to the
arms or beaters so as to ensure equal distribution of the acting gases and the
cooling fluid, and suitable inlet and outlet ways cocks valves and doors are
provided.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Charles Wigg in the Great Seal Patent Office on the 3rd January
1883.
CHARLES WIGG of Liverpool in the County of Lancaster. Alkali Manufacturer.
"IMPROVEMENTS IN THE MANUFACTURE OF CARBONATE OF SODA, AND IN APPARATUS
EMPLOYED THEREIN
"
This relates to the manufacture of carbonate of soda by the ammonia process,
that is to say the process in which ammonia and carbonic acid gas react upon brine,
or artificial solutions of common salt whereby bi carbonate of soda is formed and
precipitated in a finely divided state and is subsequently converted into mono
carbonate of soda by ignition. The main objects are, to perfect and improve the
manufacture and provide improved apparatus.
•
Under the first part. In order to precipitate any magnesium compounds contained
in the brine to be treated I add to the said brine a soluble compound of arsenic
such as arseniate of soda and I cause the unabsorbed gases from the saturators or
absorbers or the gases resulting from the roasting of the bicarbonate of soda to pass
through in contact with the said brine. The arseniate is added in quantity
sufficient to precipitate the magnesium compounds and the precipitate is roasted to
recover the arsenic and ammonia it contains.
Under the second part. In order to ensure the equal distribution of the ammonia
and carbonic acid gases throughout the brine in the saturators or absorbers. I admit
the said gases under pressure (say 30 to 40 pounds) into the brine through
perforated arms beaters or distributors rotating around a horizontal or vertical
axis.
Third In order to ensure thorough saturation of the brine or absorbtion of the
gases I employ a series of saturators or absorbers in which the gases to be absorbed
are distributed through the brine in the manner setforth under the second part
and cause the said gases to flow from one saturator or absorber to another.

page_text: Fourth. I maintain the brine during the re-actions which take place in the
saturators or absorbers at the required temperature by means of a cold or
refrigerating fluid preferably brine which is caused to flow through hollow arms or
beaters caused to rotate around an axis disposed in any suitable plane.
Fifth. Apparatus for carrying my invention into practice consists preferably of
cast iron saturators or absorbers (by preference standing upright) 'provided with
hollow arms beaters or distributors rotating around horizontal or vertical axes:
The upper rotating arms or beaters are connected with refrigerating fluid inlet or
outlet pipes, and the lower arms beaters or distributors are perforated and
connected to the ammonia and carbonic acid gas supply pipes. Gearing is employed
for communicating motion to the arms or beaters so as to ensure equal distribution
of the acting gases and the cooling fluid and suitable inlet and outlet ways cocks
Fig 1 is an elevation and fig 2 a plan of apparatus suitable for carrying my
improvements into effect. a a vertical cylindrical saturators or absorbers
preferably constructed in sections of cast iron and bolted together, though any
material capable of resisting the heat pressure and chemical action may be used.
The said saturators or absorbers are by preference made in five sections the three
central ones b being similar and interchangable. The upper and lower dome
shaped sections c are each cast in one piece and secured to the middle sections by
bolts. & brine inlet cocks, e safety valves. finlet cocks for ammonia and carbonic
acid gases. g hollow shafts connected to the ammonia gas inlet cocks and pipes f.
h perforated arms beators or distributors secured to the hollow shafts g. i pipes
and cocks for controlling the passage of brine or cooling or refrigerating fluid
through the hollow revolving arms or beaters j. k gearing for giving motion to
the arms or beaters h and j. 1 draw off cocks. m filter beds connected to the draw
off cocks by the pipes m. The pipes connections gearing stuffing boxes and like
parts are of any usual or suitable construction.
The operation of the apparatus is as follows:-
The brine previous to use is purified from lime in the usual manner by
allowing the unabsorbed gases from the saturators or absorbers or the gases
resulting from the roasting of the bi carbonate of soda to pass therethrough
previous to treatment in the saturators or absorbers. I also add to the said brine
under the first part, a soluble compound of arsenic such as the arseniate of soda in
quantity equivalent to the magnesium present the magnesium is precipitated as
the insoluble ammonia magnesia arseniate provided that, the brine is made
alkaline with ammonia. The precipitate is collected dryed and roasted to recover
the arsenic and ammonia it contains.
The purified brine is now admitted through the cock d into the saturators or
absorbers up to a suitable level, the cocks are then closed and ammonia gas is
forced through the hollow shafts g and arms beaters or distributors h up through
the brine in the first saturator or absorber of the series. The gases from the said
absorber or saturator pass off by the safety valve down through pipes into the
shaft and arms beater or distributor of the second saturator or absorber and so on
to the end of the series. In practice the ammonia gas may be passed into the
brine first and the carbonic acid gas afterwards or both may be passed through
together after previous mixing and cooling.
During continuance of the reaction in the saturators or absorbers much heat is
developed and were means not taken to prevent it, the temperature would rise so
high as to preclude the formation of bi carbonate of soda; to obviate this brine or
cooling fluid is caused to flow through the hollow rotating arms or beaters i. The
fluid is cooled or refrigerated in any usual manner. Motion is given to the arms
or beaters through gearing from any convenient source of power. When the
reaction is completed in the first saturator or absorber of the series the said

page_text: saturator or absorber is disconnected from the rest and the contained liquor and
carbonate of soda run off on to a filter bed of any usual or desired construction.
The residual gas is pumped or otherwise forced into the second saturator or
absorber of the series which now becomes the first. When recharged with brine
the disconnected absorber becomes the last of the series.
Having now described and particularized my said invention in such manner that
others will be enabled to carry my improvements into effect. I claim:-
First Precipitating magnesium compounds from brine for use in the above
mentioned soda ammonia process by means of a soluble arseniate substantially as
setforth.
Second. Admitting ammonia and carbonic acid gases at pressure into brine
through perforated rotating beaters or distributors substantially in the manner and
for the purpose setforth.
Third. A series of saturators or absorbers combined and operating substantially.
as setforth under the second part.
Fourth. Maintaining brine whilst being acted on in the saturators or absorbers
at the required temperature by means of refrigerating fluid flowing through hollow
rotating arms or beaters.
Fifth. Apparatus constructed arranged combined and operating substantially as
setforth for the purpose specified.
In Witness Whereof I the said Charles Wigg have hereunto set my hand and
seal this thirtieth day of December in the year of our Lord, one thousand
eight hundred and eighty two