Improvements in the Manufacture of Sodium Chlorate.
Year: 1897

page_text: PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Sodium Chlorate.
I, ALFRED ROLAND DAVIS, of 32, Blackfriars Street, Manchester, Chemical
Engineer, do hereby declare the nature of this invention to be as follows:-
This invention consists in subjecting finely divided dry anhydrous carbonate of
sodium to the action of chlorine gas. If the sodium carbonate be exposed to the
chlorine in very fine layers it is rapidly and almost completely converted into
chloride and chlorate of sodium but it is preferable to periodically rake it or
otherwise disturb it in order that a fresh surface may be exposed to the action of
the chlorine. It will be at once seen that by using the carbonate of sodium dry
and in powder a great advantage is gained over those processes wherein carbonate
of sodium in solution or in a semi-dry state is acted upon by chlorine for the
manufacture of chlorate as the dry powder is easier to manipulate and requires no
treatment preliminary to its use as above described.
If
The operation of acting upon the carbonate of sodium with chlorine may be
either continuous or intermittent. In the latter case though I confine myself to
no particular mode of procedure the carbonate of sodium can be spread upon the
floor of a suitable chamber and chlorine allowed to enter the said chamber.
necessary the partly transformed carbonate can then be raked or otherwise
disturbed and subjected to the action of another dose of chlorine and so on until
conversion is complete.
But I prefer to treat the carbonate of sodium with chlorine in a mechanical
apparatus wherein the carbonate is caused to travel through and in the opposite
direction to a current of chlorine so that the conversion of carbonate into chloride
and chlorate is a continuous operation.
Seeing that chlorine as commercially manufactured often contains an appreci-
able quantity of aqueous vapour which has a tendency to cause the carbonate of
sodium to cake or agglomerate and thereby be less perfectly converted into chloride
and chlorate it is advisable to overcome this difficulty if it exists by drying the
chlorine before using it for the manufacture of chlorate by this process. This may
be done in an ordinary coke scrubber the efficiency of which may be increased if
necessary by allowing strong sulphuric acid to run down it.
The mixture of chloride and chlorate resulting from the treatment of carbonate
of sidium with chlorine as above described is then washed with the minimum
quantity of hot water sufficient to dissolve out all the chlorate. It is preferable
to have a number of batches of the mixed salts undergoing the washing operation
at one time in different stages so that the weaker solutions resulting from finishing
one batch may be strengthened by use upon another batch or other batches as in
the case of the lixiviation of black ash in the Leblanc process for making alkali.
The vessels in which the washing or lixiviating is performed are preferably heated
by a steam jacket or otherwise in order that in the resultant solution the ratio of
chlorate to chloride may be the highest practically attainable. The further separa-
tion of the two salts may be effected by concentration and crystallisation in a

page_text: manner that will readily suggest itself to any one possessed of ordinary technical
chemical knowledge.
Dated this 19th day of May 1897.
ALFRED ROLAND DAVIS.
G. F. Redfern & Co.,
4, South Street, Finsbury, London, Agents for the Applica
Improvements in the Manufacture of Sodium Chlorate.
I, ALFRED ROLAND DAVIS, of 32, Blackfriars Street, Manchester, in the County
of Lancaster, Chemical Engineer, 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:-
This invention consists in subjecting finely divided anhydrous carbonate of
sodium to the action of chlorine gas. If the sodium carbonate be exposed to the
chlorine in very fine layers it is rapidly and almost completely converted into
chloride and chlorate of sodium but it is preferable to periodically rake it or other-
wise disturb it in order that a fresh surface may be exposed to the action of the
chlorine. It will be at once seen that by using the carbonate of sodium dry and
in powder a great advantage is gained over those processes wherein carbonate of
sodium in solution or in a semi dry state is acted upon by chlorine for the manu-
facture of chlorate as the dry powder is easier to manipulate and requires no
treatment preliminary to its use as above described.
The operation of acting upon the carbonate of sodium with chlorine may be
either continuous or intermittent. In the latter case though I confine myself to
no particular mode of procedure the carbonate of sodium can be spread on the
floor of a suitable chamber and chlorine allowed to enter the said chamber. If
necessary the partly transformed carbonate can then be raked or otherwise disturbed
and subjected to the action of another dose of chlorine and so on until conversion
is complete.
But I prefer to treat the carbonate of sodium with chlorine in a mechanical
apparatus wherein the carbonate is caused to travel through and in the opposite
direction to a current of chlorine so that the conversion of carbonate into chloride
and chlorate is a continuous operation.
Seeing that chlorine as commercially manufactured often contains an appreciable
quantity of aqueous vapour which has a tendency to cause the carbonate of sodium
to cake or agglomerate and therefore be less perfectly converted into chloride and
chlorate it is advisable to overcome this difficulty if it exists by drying the chlorine
before using it for the manufacture of chlorate by this process. This may be done
in an ordinary coke scrubber the efficiency of which may be increased if necessary
by allowing strong sulphuric acid to run down it.
The mixture of chloride and chlorate resulting from the treatment of carbonate
of sodium with chlorine as above described is then washed with the minimum
quantity of hot water sufficient to dissolve out all the chlorate. It is preferable
to have a number of batches of the mixed salts undergoing the washing operation
at one time in different stages so that the weaker solutions resulting from finishing
one batch may be strengthened by use upon another batch or other batches as in
the case of the lixiviation of black ash in the Leblanc process for making alkali.
The vessels in which the washing or lixiviating is performed are preferably heated
by a steam jacket or otherwise in order that in the resultant solution the ratio of

page_text: chlorate to chloride may be the highest practically attainable. The further separa-
tion of the two salts may be effected by concentration and crystallisation in a
manner that will readily suggest itself to anyone possessed of ordinary technical
chemical knowledge.
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 employment of anhydrous sodium carbonate for the manufacture of
chlorate of soda by acting upon said carbonate with chlorine.
2. The manufacture of chlorate of soda as a continuous operation by causing
anhydrous sodium carbonate to be mechanically moved through an atmosphere of
chlorine gas until the decomposition of the carbonate into chloride and chlorate is
complete or practically complete.
3. The manufacture of chlorate of soda by treating anhydrous carbonate of
sodium with dried chlorine gas and from the mixed chlorate and chloride so
obtained extracting the chlorate by differential lixiviation in jacketted lixiviating
tanks.
Dated the 19th day of February 1898.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicant.