IMPROVEMENTS IN THE MANUFACTURE OF CHLORATE OF SODA, PARTLY APPLICABLE ALSO TO THE MANUFACTURE OF CHLORATE OF POTASH
Year: 1881

page_text: LETTERS PATENT to Walter Weldon, of Rede Hall, Burstow, in the County of
Surrey, for an Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
CHLORATE OF SODA, PARTLY APPLICABLE ALSO TO THE MANUFACTURE OF
CHLORATE OF POTASH." A communication from abroad by Alfred Rangod
Pechiney, of Salindres, in the Republic of France.
PROVISIONAL SPECIFICATION left by the said Walter Weldon at the
Office of the Commissioners of Patents on the 1st February 1881.
WALTER WELDON, of Rede Hall, Burstow, in the County of Surrey. "IMPROVE-
MENTS IN THE MANUFACTURE OF CHLORATE OF SODA, PARTLY APPLICABLE ALSO
TO THE MANUFACTURE OF CHLORATE OF POTASH." A communication from
abroad by Alfred Rangod Pechincy, of Salindres, in the Republic of France.
The manufacture of chlorate of soda, as at present conducted, requires the
preliminary formation of chlorate of potash. The present Invention consists in
manufacturing chlorate of soda directly from the mixed solution of chlorate of lime
and chloride of calcium produced by the reaction of chlorine gas upon milk of
lime.
By the present Invention the said mixed solution of chlorate of lime and chloride
of calcium is treated by sulphate of soda, preferably in quantity as nearly as inay
be equivalent to the whole of the calcium salts present, the immediate products
being chlorate of soda, chloride of sodium, and sulphate of lime. The sulphate of
lime for the most part falls as crystals, which are collected, filtered, and washed.
To the mother liquor and wash waters enough carbonate of soda is then added to
precipitate any remaining calcium salts, after precipitation of which there remain
in solution only chlorate of soda and chloride of sodium. The mixed solution of
chlorate of soda and chloride of sodium is now evaporated, until it attains a density
of about 48 degrees Beaumé, corresponding to a specific gravity of about 1-485.
During this evaporation chloride of sodium falls, and should be fished out. When
[Price 41

page_text: the solution, from which as much chloride of sodium as possible has been removed,
has attained the density above mentioned, on cooling it yields crystallized chlorate
of soda.
The sulphate of soda used in this method of manufacturing chlorate of soda may
conveniently be added to the mixed solution of chlorate of lime and chloride of
calcium as solid crystallized hydrate. This is not essential however, but the
sulphate of soda may also be added either in solution or as solid anhydrous
sulphate.
The sulphate of lime precipitated in this method of manufacturing chlorate of
soda will require washing to remove all adherent chlorate of soda from it. My
correspondent prefers to wash this sulphate of lime with hot water, using the
smallest quantity possible, and then to utilize the chlorate of soda in the resulting
wash-waters into the much less soluble salt chlorate of potash, by adding to the
wash-waters chloride of potassium. In the same series of operations he thus
manufactures not only chlorate of soda, but also chlorate of potash.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Walter Weldon in the Great Seal Patent Office on the 20th July
1881.
WALTER WELDON, of Rede Hall, Burstow, in the County of Surrey. "IMPROVE-
MENTS IN THE MANUFACTURE OF CHLORATE OF SODA, PARTLY APPLICABLE ALSO
TO THE MANUFACTURE OF CHLORATE OF POTASH." A communication from Alfred
Rangod Pechiney, of Salindres, in the Republic of France.
The manufacture of chlorate of soda as at present conducted requires the pre-
liminary formation of chlorate of potash. The present Invention consists in
manufacturing chlorate of soda directly from the mixed solution of chlorate of limo
and chloride of calcium produced by the reaction of chlorine gas upon milk
of lime.
By the present Invention the said mixed solution of chlorato of lime and chloride
of calcium is treated by sulphate of soda, preferably in quantity as nearly as may
be equivalent to the whole of the calcium salts present. There are then formed
chlorate of soda, chloride of sodium, and sulphate of lime. The chlorate of soda
and the chloride of sodium remain in solution, but the sulphate of lime for the
most part separates out as crystals. These crystals are separated from the mother-
liquor by filtration or otherwise. My correspondent recommends for this purpose
the centrifugal hydro-extractor. To the mother-liquor enough carbonate of soda is
then added to precipitate any remaining calcium salts, after precipitation of which
there remain in solution only chloride of sodium and chlorate of soda. Tho
precipitate having been separated by filtration or otherwise, as will be well under-
stood, the mixed solution of chloride of sodium and chlorate of soda is evaporated,
preferably until it attains a density of about fourty-four degrees Beaumé, corre-
sponding to a specific gravity of about 1428. Or the evaporation may be carried
until the density of the solution is forty-eight degrees Beaumé, corresponding to a
specific gravity of 1.485; but my correspondent believes it to be better not to
overpass fourty-four degrees Beaumé. During this evaporation chloride of sodium
falls and should be fished out. When the solution has attained the desired density,
and as much chloride of sodium as possible has been removed from it, it is allowed
to cool, when it yields crystals of chlorate of soda.
The sulphate of lime precipitated in this method of manufacturing chlorate of
soda will require washing to remove from it adherent chlorate of soda. My
correspondent prefers to wash it with hot water, using the smallest quantity thercof
practicable, and then to utilize the chlorate in the said wash-waters by adding to
them chloride of potassium, and so converting the said chlorate of soda into the
much less soluble salt, chlorate of potash. The chloride of sodium fished out from
the boiling mixed solution of chloride of sodium and chlorate of soda will also
require washing, and the chlorate of soda in the wash-waters from it also may be
utilized in the same way. Or the wash-waters alike of the said sulphate of lime,
of the said chloride of sodium, and of the precipitate formed by adding carbonate
of soda to the mixed solution of chloride of sodium and chlorate of soda, may be
used for making milk of lime for the next operation, or be added to the next
quantity of crude liquor, as may be preferred.
In witness whereof, I, the said Walter Weldon, have hereunto set my hand
and seal, this
day of July, in the year of our Lord One
WALTER WELDON. (L.S.)