Carbonate of Soda and Caustic.
Year: 1885

page_text: Carbonate of Soda and Caustic Soda.
I, CHARLES WIGG of Walmer Buildings, Water Street Liverpool, in the county of
Lancaster Alkali Manufacturer do hereby declare the nature of the said invention
for IMPROVEMENTS IN AND IN APPARATUS FOR THE MANUFACTURE OF CARBONATE
OF SODA AND CAUSTIC SODA to be as follows :-
The invention relates to improvements in apparatus used in the manufacture of
carbonate of soda by the ammonia process and the object is to provide apparatus so
improved in construction arrangement and combination that the manufacture of
carbonate of soda can be carried on economically and with little or no waste
of carbonic acid and ammonia.
My invention consists essentially in the combination of carbonic acid generators
and purifiers with saturators, carbonators, filters, furnaces, and apparatus for
recovering and re-using carbonic acid and ammonia in the novel manner berein-
after set forth and in the improved construction of parts of the apparatus.
Apparatus under my invention is constructed essentially as follows:-
First. A cast iron vertical cylinder or generator is provided with supply and
discharge ways and with a false bottom of stoneware on which a charge of
carbonate of lime preferably limestone rests and is connected by a pipe from the
bottom with an overhead vessel hereafter termed the acid "egg" it is connected at
the top by means of a pipe with a washing vessel placed alongside. Pipes connect
the egg with an acid cistern and with a vacuum pump.
Both the above mentioned
pipes are opened or closed at will by two regulating valves which have lead alloy
plugs at their extremities and spindles covered with the same alloy.
The apparatus in action is manipulated thus:-The lid or cover of generator is
taken off and the charge of limestone admitted from a hopper; the lid is then
replaced. A vacuum is next produced in the acid egg by means of a pump and
when sufficient exhaustion has been obtained, communication with the acid cistern
is effected by opening a valve. The acid then enters the egg until the valve
leading to the acid cistern is shut, then communication is opened with the generator
and the acid is allowed to flow beneath the false bottom and through the generator.
The mixture of the limestone and acid results in the evolution of carbonic acid
which is conveyed away through the washing vessel containing water and the
...
077

page_text: purified gas then flows into the carbonators which are preferably made in the
manner set forth in the specification to British Letters Patent N° 3125**
Second. Vessels for the preparation of brine or sulphate of soda solution and its
subsequent saturation with ammonia are connected to one another by two series of
cross pipes the higher of which serves for adjusting the levels of the contents of the
various vessels whilst the lower are connected with the ammonia stills. A cock or
valve is provided at the junctions of the lower set of cross pipes so that the
ammonia gas can only pass into one saturator at a time. In each saturator is
placed a cage of stout wire gauze or equivalent material which serves to receive
the charge of salt or sulphate of soda and to preserve it in a situation favourable to
dissolution. From an opening in the top of each saturator proceeds a pipe leading
to a small tower containing acid for the capture of any traces of ammonia escaping
from the saturators. I operate these saturators by half filling each with water then
passing in dry or nearly dry ammonia gas from suitable stills and from time to
time charging salt into the cage. This is continued until sufficient salts has entered
into solution by which time an equivalent of ammonia will have been absorbed.
The liquor containing the salt and ammonia after settling and blowing off
impurities is allowed to pass through suitable connections into the carbonators
already mentioned. Sulphate of soda solution is prepared and used in an analogous
manner. In certain circumstances I find that the waste sulphate of soda liquors of
copper extractors may be advantageously used in the above apparatus after the
separation of the iron therefrom for the production of bicarbonate of soda. In
the carbonators the liquor is subjected to the action of carbonic acid from the
generator described under part one. Any unabsorbed excess of carbonic acid from
the carbonators passes into the saturators and thence to the washing tower after
which it passes to a gasometer or collector whence it is distributed for reuse in the
carbonators.
Third. In combination with the above described apparatus I make use of filters
onto which bicarbonate of soda from the carbonators is run and furnaces where
the said carbonate is roasted and the carbonic acid and ammonia given off are
recovered by suitable appliances.
In place of roasting furnaces I may employ a drying oven the temperature of
which does not exceed 140° F to 160° F.and in which the bicarbonate is allowed
to travel on endless bands and is withdrawn and sold as bicarbonate of soda.
The bicarbonate may be converted into caustic soda by boiling it with water till
the greater part of the CO₂ has been expelled and then adding lime equivalent to
the carbonic acid remaining in the diluted liquor. After subsidence of the pre-
cipitated carbonate of lime the caustic solution is treated according to well known
methods for obtaining solid caustic soda.
1.300

page_text: Carbonate of Soda and Caustic Soda.
I CHARLES WIGG of Walmer Buildings Water Street Liverpool in the County of
Lancaster Alkali 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:-
The invention relates to improvements in and in apparatus used in the manu-
facture of carbonate of soda by the ammonia process and the object is to provide
apparatus so improved in construction arrangement and combination that the
manufacture of carbonate of soda can be carried on economically and with little or
no waste of carbonic acid and ammonia.
My invention consists essentially in the combination of carbonic acid generators
and purifiers with saturators, carbonators, filters, furnaces and apparatus for
recovering and removing carbonic acid and ammonia in the novel manner herein-
after set forth and the improved construction of parts of the apparatus.
Apparatus under my invention is constructed essentially as follows:-
"
First., A cast iron vertical cylinder or generator is provided with supply and
discharge ways and with a false bottom of stoneware on which a charge of.
carbonate of lime preferably limestone rests and is connected by a pipe from the
bottom with an over head vessel hereafter termed the acid " egg it is connected
at the top by means of a pipe with a washing vessel placed alongside, pipes connect.
the "egg
"with an acid cistern and with a vacuum pump Both the above
mentioned pipes are opened or closed at will by two regulating valves which. have.
lead alloy plugs at their extremities and spindles covered with the same alloy, or
ebonite or the like may be used.
The apparatus in action is manipulated thus The lid or cover of the generator
is taken off the charge of limestone admitted from a hopper the lid is then replaced;
-A vacuum is next produced in the acid ". egg" by means of a pump and when
sufficient exhaustion has been obtained, communication with the acid cistern is
effected by opening a valve-The acid then enters the "egg" until the valve leading
to the acid cistern is shut then. communication is opened with the generator and
the acid is allowed to flow beneath the false bottoin and through the generator
The mixture of the limestone and acid results in the evolution of carbonic acid
which is conveyed through the washing vessel containing water and the purified
gas then flows into the carbonators which are preferably made in the manner set;
forth in the specification to British Letters patent No-31258..
Second. Vessels for the preparation of brine or sulphate.of soda solution and its
subsequent saturation with ammonia are connected to one another by two series of
cross pipes the higher of which serves for adjusting the levels of the contents of
the various vessels, whilst the lower are connected with the ammonia stills,. A cock
or valve is provided at the junctions of the lower section of cross pipes so that
the ammonia gas can only pass into one saturator at a time. In each saturator is.
placed a cage of stout wire gauze or equivalent, material which serves to receive

page_text: the charge of salt or sulphate of soda and to preserve it in a situation favourable to
dissolution. From an opening in the top of each saturator proceeds a pipe leading
to a small tower containing acid for the capture of any traces of ammonia esccaping
from the saturators. I operate these saturators by half filling more or less, each
with water, then passing in dry or nearly dry ammonia gas from suitable stills,
and from to time charging salt into the cage-This is continued until sufficient
salts have entered into solution by which time an equivalent of ammonia will have
been absorbed. The liquor containing the salt and ammonia after settling and
blowing off impurities is allowed to pass through suitable connections into
carbonators already mentioned. Sulphate of soda solutions is prepared and used
in an analogous manner. In certain circumstances I find that the waste sulpbate
of Soda Liquors of Copper exhausters may be advantageously used in the above
apparatus after the separation of the Iron therefrom for the production of Bi-
carbonate of Soda.-In the carbonators the liquor is subjected to the action of
Carbonic Acid from the generator described under part one-Any unabsorbed
excess of carbonic acid from the carbonators pass into the saturators and thence
to the washing tower after which it passes to a gasometer or collector whence it is
distributed for re-use in the carbonators.
Third. In combination with the above described apparatus I make use of filters
into which bicarbonate of soda from the carbonators is run and furnaces where the
said' carbonate is roasted and the carbonic acid and ammonia given off are recovered
by suitable appliances.
In place of roasting furnaces I may employ a drying oven the temperature of
which does not exceed 140° F to 160 F and in which the bicarbonate is allowed
to travel on endless bands and is withdrawn and sold as Bicarbonate of Soda.
The Bicarbonate may be converted into caustic soda by boiling it with water
till the greater part of the CO₂ has been expelled and then adding lime equivalent
to the carbonic acid remaining in the diluted liquor,-After subsidence of the
precipitated carbonate of lime the caustic solution is treated according to well
known methods for obtaining solid caustic soda.
The accompanying sheet of drawings illustrates the three heads of my invention
and shews what I have found to be the most effective construction and disposition
of my improved apparatus.
Fig. 1 is a plan and Fig. 2 an elevation shewing the general arrangement of the
parts. Fig. 3 is a verrical section of part of the acid generating apparatus and
Figs. 4 and 5 vertical and horizontal sections of the Carbonators. Fig. No 1, 1 acid
tank 2 float connected to an acid supply valve of any suitable construction so as
to regulate the height of the acid in the said tank, 3 pipes leading from the tank 1
to the acid eggs 4, beneath the valve 5. 6 valve controlling the opening to the
pipe 7 leading from the acid egg 4 beneath the grid 8 near the bottom of the
carbonic acid generator 9. The valves and valve spindles 5 and 6 are clothed with
lead or ebonite to resist the action of acid 10 waste cock at the bottom of 9
11 carbonate of lime hopper, 12 door at top of carbonic acid generator beneath the
hopper 11. Bolts and nuts or equivalent means are provided for maintaining the
door 12 securely in position whilst the carbonic acid gas is being generated,
13 exhaust pump connected by the pipe 14 to the acid egg 4 at 15 and to the
delivery pipe 10 of the carbonic acid generator 9. 17 safety valve and escape
pipe 18, 19, 20 regulating cocks. The delivery pipe 16 is led to near the bottom
of a washer 16 From the top of the washer 16* a pipe 21 leads to the circulating
pipe 22.
The action of the above part of the apparatus is as follows. The lid or cover of
the generator 9 is taken off and a charge of limestone admitted from the hopper 11
and the cover is then replaced, a vacuum is next produced in the acid egg by means
of the pump 13 the cock 18 being open and 19 closed and when sufficient exhaustion
has been obtained the cock 18 is closed and communication is opened by the valve 5
with the acid cistern 1. The acid flows into the egg until the valve 5 is shut,
communication is then opened by the valve 6 from the bottom of the egg 4 to the

page_text: bottom of the generator 9 and by the cock 19 between the top of the egg and the
top of the generator so as to obtain an equilibrium of pressure. The acid then flows
down the pipe 7 'beneath the grid 8 and up amongst the limestone in the generator.
The admixture of limestone and acid results in the evolution of carbonic acid gas
which passes by the pipe 16 through the washer 16* which is filled with water and
by the pipe 21 to the circulating pipe 22. If the gas attains an undesirable pressure
in the generator the excess will escape past the safety valve 17. The waste chloride
of calcium solution produced is drawn off from time to time through the cock 10.
23 indicates a still for the production of gaseous ammonia. This still may be of
any usual or convenient kind and of itself forms no part of my invention and may
be of simple or complex construction and any convenient number may be used.
From the still 23 a pipe 24 leads to the open bottom tap 25. The plug of the said
tap has a way leading from the bottom to one side and may be made to commu-
nicate with any one of the branch pipes 26 leading to the saturators 27. Within
each saturator is a perforated or wire gauze cage 28. 29 hoppers and covers to
saturators 30.pipe leading from the hoppers to a wash tower 31. 32 gas exit pipe.
To avoid confusion the pipe 30 is shewn connected to one hopper only. 33 draw off
cocks at bottom of saturator, 34 pipes and cocks between saturators to allow of free
communication being opened from one to another so that the contents in each may
be at a uniform height, 35 pipes leading from the saturators to the cock 36 similar
in construction to the cock 25. From the bottom of the cock 36 a branch pipe 37
leads to the carbonators 42.
In using the above part of my apparatus one or more of the saturators is or are
filled with water to near the top in any convenient way and the cages 28 are filled
with sodic chloride or sulphate. The covers 29 are then secured in position and
ammonia from the still 23 turned into one of the saturators until the sodic solution
bas absorbed the required quantity, the cock 25 is then turned and the ammonia
allowed to enter another absorber.
The pipe 22 is connected by cross pipes 38 with the endless pipe 39 fitted with
cocks 40 and having pipes 41 leading to the top of the carbonators 42 beneath
safety valves 43. Within the carbonators are two sets of revolving beaters com-
posed of hollow shafts 44, hollow discs 45, and hollow connecting arins 46. The
hollow shafts pass through stuffing boxes 47 on the carbonators and stuffing
boxes 48 on standards 49 into one or other of the compartments 50, 51. 52 inlet
pipe to the compartment 50 on the standard at one end of the apparatus, an outlet
pipe being provided on the standard at the other end. The compartments 51 of
the standards are connected by cocks 53 with the cross pipes 38. 54 driving gear
for giving motion to the revolving beaters, 55 draw off cocks connected by pipes 56
to filter presses 57. 58 discharge pipes from filters, 59 furnaces. The filter presses
are of any usual construction and may vary in number and position according to
their size. A convenient construction of filter consists of a cylindrical vessel
divided into two portions by a diaphragm of porous material. The furnaces are
closed calcining furnaces of any usual or suitable construction.
The operation of the above part of the apparatus is as follows. The sodic
ammonia solution in the saturators after any impurities have been blown off
through the cocks 33, is allowed to flow down the pipe 37 into the carbonators
when the carbonators are filled, carbonic acid gas from the generator 9 is admitted
past one of the cocks 53 through one of the lower hollow beaters, the arms of which
are perforated, into one of the carbonators it thence passes by the pipes 41, 39, into
the 2nd and 3rd carbonator, the cocks 53 and 40 being suitably disposed for that
purpose. As will be well understood any excess of carbonic acid passes by the
pipe 37 to the saturators and thence by the pipe 30 to the wash tower 31 and
discharge pipe 32 to a gasometer or suitable receptacle from which it may be
returned to the carbonators. During reaction the contents of the carbonators are
kept at the required temperature by water flowing through the upper hollow
beaters. The precipitated contents of the carbonators are run through the pipes 56
into the filters 57 from which the bicarbonate is removed and washed and roasted

page_text: at a high temperature in the furnaces 59 the carbonic acid and ammonia given off
being recovered and re-used in the saturators Instead of roasting the bicarbonate
at a high temperature it may be treated in drying ovens instead of furnaces 59 or
it may be converted into caustic soda.
The filtrate drawn off through the pipes 58 is when chloride of sodium is used
in the saturators boiled with lime and the gaseous ammonia is reused in the process
or it may be boiled down and crystallized or otherwise treated When sulphate of
soda is used in the saturators the filtrate is boiled to obtain crystals of sulphate of
ammonia or it is mixed with common salt and chloride of ammonia obtained. It
will be obvious that the number of generators absorbers carbonators and filters
may be varied and the grouping altered without departing from my invention.
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
First. The manufacture of carbonate of soda and caustic soda by the apparatus
and in the manner herein setforth.
Second. Apparatus for generating carbonic acid gas substantially as hereinbefore
setforth.
Third. Apparatus for the preparation and saturation of brine or sulphate of soda
substantially as herein before setforth.
Fourth. The combined apparatus hereinbefore specified for the manufacture of
carbonate of soda and caustic soda substantially as hereinbefore.setforth.
Fifth. The combination of tank 1, acid egg 4 and valves and connections with
the generator 9.
Sixth. The combination of the saturators 27 with valves and connections
substantially as setforth.
Seventh. Saturators 27 with cages 28 substantially as setfortb.
Eighth. The combination of saturators 27 and wash towers 31 substantially as
setforth.
Ninth. The combination of saturators 27 with ammonia stills 23 substantially as
setforth.
Tenth. Carbonators 42 with hollow rotating beaters for the purposes setforth.
Eleventh. The combination of carbonators with connecting pipes and valves
substantially as setforth.
Twelfth. The combination of generators saturators and carbonators substantially
as setforth.
Dated this 9th day of January 1886.