Improvements in the Manufacture of Ohlorates: of Sodium and Potassium.
Year: 1894

page_text: Date of Application, 1st Oct., 1894
Complete Specification Left, 31st July, 1895-Accepted, 1st Jan., 1898.
"
Improvements in the Manufacture of Ohlorates: of Sodium and
Potassium.
We JAMES HARGREAVES of Farnworth-in-Widnes in the County of Lancaster
Chemical Engineer and THOMAS BIRD. of Cressington in the same county
Electrical Engineer do hereby declare the nature of this invention to be as
follows:-
:--
Our improvements consist in the direct production of sodium chlorate by passing
chlorine through or over caustic soda or sodium carbonate, in solution or otherwise.
In practice we use two or more absorbing vessels containing the soda to be acted on.
A current of chlorine is passed through the said vessels, which are arranged in such
a manner that the chlorine enters the vessel in which the conversion into chlorate is
most nearly complete. The unabsorbed chlorine, together with any other gas then
passes into another vessel or series of vessels, also charged with soda as aforesaid,
until the chlorine is completely absorbed or nearly so. During the reaction a
quantity of sodium chloride is precipitated; and when a sodium carbonate is used, or
when the chlorine is mixed with carbonic acid, there is also sodium bicarbonate
precipitated. To ensure that all the available soda is utilised we use suitable
agitators, so as to bring the said sodium bicarbonate into contact with the chlorine.
To obtain a greater degree of concentration of the liquors we in some cases add an
excess of sodium carbonate beyond what the water will take into solution. To
separate the sodium chlorate from the sodium chloride we place the aforesaid
precipitated sodium chloride in a filtering vessel with suitable perforations in the
bottom, and force a current of steam through the mass of the said sodium chloride,
or we use a hydro-extractor and pass steam through the mass of sodium chloride
while being revolved in the said hydro-extractor.
As a convenient means of causing a current of chlorine to pass through aforesaid
absorbing vessels, where pressure to force the chlorine is not available, we use any
suitable form of exhauster, and where metal oxhausters are used we use a wash
tower or absorbing vessel charged with soda or other absorbing material to take up
the last traces of chlorine before the gases arrive at the exhauster.
We do not confine ourselves to any particular form of absorbing vessels.
Absorbing towers or other forms of absorbing apparatus may also be used, with
provision for removing the precipitated sodium chloride and for agitating the
precipitated sodium bicarbonate so as to bring the said sodium bicarbonate into
contact with the chlorine.
The said sodium bicarbonate may also be decomposed by keeping the solution
heated during the treatment with chlorine.
As an alternative method, sodium bicarbonate may be used instead of ordinary
sodium carbonate.
To produce potassium chlorate we react upon sodium chlorate by the addition of
an equivalent of potassium chloride in solution, and separate the resulting salts by
crystallization.
September 29th 1894.
JAMES HARGREAVES,
Farnworth-in-Widnes.
THOMAS BIRD,
Cressington, Liverpool.

page_text: Improvements in the Manufacture of Chlorates of Sodium and
Potassium.
We, JAMES HARGREAVES, of Farnworth-in-Widnes, in the County of
Lancaster, Chemical Engineer, and SARAH BIRD, Widow and Executrix of the
lately deceased THOMAS BIRD, of Cressington, in the same county, Electrical
Engineer, do hereby declare the nature of this invention and in what manner the
Bame is to be performed to be particularly described and ascertained' in and by
the following statement :-
This invention relates to the direct production of sodium chlorate, by passing
chlorine through or over caustic soda (or sodium carbonate or bicarbonate) in
solution or otherwise.
In carrying out this invention, we employ two or more absorbing vessels arranged
in series; and containing the solution of soda to he acted upon. A current of
chlorine passes successively through the several vessels, the operation being carried
out in such a manner that the chlorine enters by the vessel in which the conversion
into chlorate is most nearly complete. The unabsorbed chlorine, together with
any other gas passes thence into another of the vessels, all of which are similarly
charged with soda, until the chlorine is wholly absorbed or nearly so. During the
reaction which takes place, a quantity of sodium chloride is precipitated; and,
when sodium carbonate or bicarbonate is used, or when the chlorine is mixed with
the carbonic acid, sodium bicarbonate is also precipitated. To ensure the utilization
of the whole of the available soda, we employ suitable agitators, whereby the entire
volume of undissolved carbonate and precipitated sodium bicarbonate is brought
into contact with the chlorine. In some instances, with a view to obtaining a
greater degree of concentration of the liquors, the caustic soda or sodium carbonate
or bicarbonate may be in excess of that which the water will take into solution.
To separate the sodium chlorate from the sodium chloride, the. precipitated
sodium chloride is drawn off and conducted to a filtering vessel provided with
suitable perforations in the bottom; a current of steam being forced downwards
through the residual mass of sodium chloride, with a view to dissolving and
washing out the sodium chlorate. Or a hydro-extractor may be employed for the
purpose; steam being passed through the mass of sodium chloride whilst under
treatment in the hydro-extractor. The materials remaining in solution consist of
sodium chlorate and sodium chloride; but in ordinary working, sodium chloride is
present in excess in a state of suspensiou. This solution is then concentrated by
any known means, during which process a large proportion of the remaining
chloride falls out of solution; and having been removed is freed from the adhering
chlorate by washing the same with the liquor from the absorbing vessels. For
effecting the more complete separation and removal of the chlorate from the
chloride, steam may be employed, as hereinbefore described. The concentration
of the solution should be continued until it acquires a specific gravity of 1.5 to 1-6,
equal to 100 to 120 degrees of Twaddels bydrometer; the solution being then run
into the crystallising vessels.
As a convenient means of introducing a current of chlorine through thic
absorbing vessels, where pressure to force the chilorine is not available, an
exhauster may be employed. Where metal exhausters are used, we employ a
wash tower or absorbing vessel, charged with soda or other absorbing material, to
take up the last traces of chlorine before the gases arrive at the exhauster.
We do. not confine ourselves to any particular form of absorbing vessels.
Absorbing towers, or other forms of absorbing apparatus may be used; provision
being made for removing the precipitated sodium chloride, and for agitating the

page_text: precipitated sodium bicarbonate, so as to bring the said precipitate into contact
with the chlorine.
The accompanying drawings illustrate by way of example, apparatus adapted
for carrying out the manufacture of chlorates according to
method.
.
Fig. is a vertical section of one of the absorbing vessels.
our improved:
3.
Fig. 2 represents in plan four of the said absorbing vessels arranged in series
although it will be understood a greater or less number may be employed.
according to requirements.
Fig. 3 is a section taken along the line 3-3 in Fig. 2.
Fig. 4 is an end elevation.
Fig. 5 is a vertical section of an absorbing tower, shown (for sake of clearness)!
combined with Fig. 3.
The absorbing vessel A is formed with two compartiments a a¹; the one.
communicating with the other by means of openings a³, as, in the walls of the
inner compartment a'. An agitator or beator B'is arranged in the compartment al,.
the blades being so arranged as to effect a mixture of the gas with the liquid, and,
at the same time, to exert a downward pressure upon the solution contained in.
that compartment; thereby maintaining the solution in the compartment a at a
level above the perforations a³. By these means, a constant circulation of the
solution is secured. On the rapid rotation of the beater, the solution is so
agitated as to be converted into foam, in which condition it rises in the outer
compartment a; and reaches the inner compartment a' through the perforations a³,
in the form of small jets. The blades b, above the level of the solution in the
compartment a!, then take the solution and further separate its particles; the
entire volume of the solution and precipitate being thus brought into contact
with a current of chlorine, which is caused to pass through the said absorbing:
Vossel. The shaft B' of the beater B is furnished with a water seal B2, and may
be rotated by bevel gearing B' operated by any convenient means. The chlorine
onters the compartment at of the absorbing vessel A by the pipe C; escaping
from the compartment a by way of the pipe D to the next vessel of the series, or.
elsewhere as may be required. The pipes C and D are preferably arranged so. as.
to be interchangeable, in order that the gas may be taken directly from the gas.
main, or from another vessel in the series, as desired or so that one or more of the.
vessels may be thrown out of use. Any suitable means may be employed at C¹
and D' for sealing the joints of the pipes C and D. In the drawings, these pipes
are shown as dipping into water seals.
The
It will be perceived that on rotating the beater B, the effect will be to beat the
solution into a foam and lower the level of the solution in the compartment a¹, so
that the solution and precipitate will be forced to return in the form of small
jets through-the perforations a³; the gas meanwhile entering the compartment a¹
by the pipe and intimately mixing with the sprayed or finely divided solution
and precipitate. Such of the chlorine as may not be absorbed in one vessel passes
by way of the connecting pipe D to the next succeeding vessel in the series..
Each vessel A is provided with a pipe c (furnished with a stop-cook) for con-
ducting the solution and precipitated chloride to a suitable filter, where they are
trented for the separation of the chlorate as hereinbefore described.
uuabsorbed gas or accumulated gases, issuing from the last vessel in the series, may
be conveyed by the pipe E to an absorbing tower F (Fig. 5), placed at a con-
venient distance from the absorbing vessels A A. This tower is furnished with
a perforated floor upon which rests a quantity of coke d. A perforated plate or
cover is also placed over the coke, and forms the floor of a compartment into
which is run a weak solution of soda (sodium oxide or sodium carbonate). The
strength of this solution should be such that it will not precipitate the sodium
bicarbonate remaining after absorption of the chlorine. The weak liquor, after
traversing the mass of coke, passes away by the pipe G and is utilized in preparing

page_text: the strong soda solution for treatment in the absorbing vessels (A); the waste
gases escaping by way of the pipe H to a chimney, or to an exhausting apparatus.
In the production of potassium chlorate, we react upon sodium chlorate by the
addition of an equivalent of potassium chloride in solution; the resulting salts
being separated by crystallisation.
1
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, we claim :
1. The improved process for the direct manufacture of sodium chlorate, sub-
stantially as horoin described, and consisting in passing chlorine through or over
sodium oxide, sodium carbonate or sodium bicarbonate, in solution or otherwise,
whilst subject to agitation in a closed vessel, separating the precipitated chloride
by filtration and recovering the chlorate from the decanted' liquid by evaporation
or other known means..
2: The improved process for the mauufacture of potassium chlorate, consisting
in reacting upon sodium chlorate with an equivalent of potassium chloride,
substantially as herein described.
1
3. The improved means applicable for use in the production of sodium and
potassium chlorate, arranged or operating substantially as described with reference
to the accompanying drawings.
4. In the manufacture of sodium and potassium chlorates, an absorbing vessol,
such as A, provided with means for agitating or beating the solution contained
therein, and arranged to operate substantially as described with reference to the
accompanying drawings.
5. In an absorbing vessel; the combination with an inner compartment a¹ and an
outer compartment a, communicating with one another, of an agitator or beator B,
arranged to work in the inner. compartment, substantially as and for the purpose
set forth.
6: In the manufacture of sodium and potassium chlorates, the employment of a
series of interchangeable absorbing vessels, arranged or operating substantially as
herein described.
7. In the manufacture of sodium and potassium chlorates, the employment of an
absorbing tower, such as F, arranged substantially as described with reference to
the accompanying drawings, and for the purpose set forth.
Dated this 27th day of July 1895
..
Dated this 27th day of July 1895
For the Applicants,
G. G. M. HARDINGHAM,
191, Fleet Street, London, E.C., Chartered Patent Agent.