Improvement in the Manufacture of Potassium Chlorate.
Year: 1894

page_text: Date of Application, 21st Sept., 1894
Complete Specification Left, 10th Apr., 1895-Accepted, 11th May, 1895
PROVISIONAL SPECIFICATION.
Improvement in the Manufacture of Potassium Chlorate.
I, KARL JOSEF BAYER, Doctor of Philosophy, and Technical Chemist, of
Brünn, in the. Austro-Hungarian Empire, do hereby declare the nature of this
invention to be as follows:-
It is known, that by the usual method of manufacture of potassium chlorate only
about one fifth of the chlorine gas produced is utilised, while four fifths is lost as
chloride of calcium.
The object of my invention is not, to increase the amount of potassium chlorate
obtained, but to utilise the remainder of the produced chlorine, which is generally
lost as chloride of calcium.
By my invention I use-instead of lime-oxide of zinc, which I can obtain at a
low price from the zinc works, or produce myself by burning metallic zinc or in
any other manner.
I first wash the oxide of zinc, which should be, if possible, free from oxide of
iron or manganese compounds, with water, and then lead the chlorine through it,
till the oxide of zinc is dissolved, and there remain but few impurities. By this
means hypochlorite of zinc is formed, with chloride of zinc, the former divides
itself when heated, in similar manner as the hypochlorite of calcium, into chlorate
of zinc and chloride of zinc. If much oxide of iron or a large quantity of
manganese compounds is present, the chlorate of zinc may be easily decomposed
under oxygen development. If we mix this solution of chlorate of zinc and chloride
of zinc at about 20°-22° Be. with the corresponding quantity of potassium
chloride (KC1), it dissolves and on cooling, potassium chlorate may be obtained
perfectly pure by a single re-crystallisation.
.
Any zinc contained in the solution poured off is in the shape of chloride of zinc,
this is again boiled down to about 30°-32° Be. by which means some of the
potassium chlorate remaining in solution is caused to crystallise out on cooling,
while the chloride of zinc solution now remaining contains only traces of
potassium chlorate which may be neglected. The chloride of zinc solution is
boiled down to the point of solidification (70° Be.), poured into casks and is then
ready for the market. It is as pure for all technical employments as chloride.of
zine obtained in any other manner.
Dated this 20th day of September 1894.
.
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant.
Improvement in the Manufacture of Potassium Chlorate.
I, KARL JOSEF BAYER, Doctor of Philosophy, and Technical Chemist, of
Brünn, in the Austrian Empire, 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 :-
It is known, that by the usual method of manufacture of potassium chlorate only

page_text: about of the chlorine gas produced is utilised, while ½ are lost as chloride of
calcium.
The object of my invention is not, to increase the quantity of potassium chlorate
obtained, but to utilise the said remainder of the chlorine, which as stated above
amounts to about of the total produced and is generally wasted as chloride of
calcium.
For this purpose I use instead of lime-oxide of zinc, which may be obtained
cheaply in the shape of zinc white from zinc works, or may be specially produced
by burning metallic zinc, or in any other manner.
The oxide of zinc should, however, be as free as possible from iron, manganese,
arsenic and antimony, in order to avoid waste. I prefer to effect the saturation of
the oxide of zinc which has been washed with water, by immediately adding the
equivalent quantity of potassium chloride, that is to say 1 equivalent of KCI for
3 equivalents of ZnO.
Before admitting the chlorine gas, the composite solution should be heated to a
temperature ranging between 95 and 98° C. because this temperature is necessary
to avoid the precipitation or separation of a basic chloride of zinc (oxychloride),
and the same procedure provides a means for, causing as much as possible of the
oxide of zinc to enter into basic (alkaline) solution. Care should also be taken,
that the quantity of water added is neither too small nor too large, as in the
former case too little oxide of zinc would enter into solution, and the latter case
would lead to the formation of oxychloride which is sparingly soluble.
It seems, that by conducting the process in the manner described, chlorate of
zinc or of potash is produced directly, without the intermediate formation of
hypochlorite.
A sample of the clear liquors obtained is first tested, by adding water, to
ascertain, whether they are basic (containing oxide of zinc), in which case a
precipitate is produced. If the addition of water has no such effect, some oxide of
zine is added and then the liquors boiled down to about 40° Be. After the liquors
have cooled and the potassium chlorate has crystallised out (which chlorate can be
easily purified and is recrystallised) the mother liquor is further concentrated to
60° Be., cooled and refrigerated to 0° C. in order to yield a further portion of the
potassium chlorate.
Subsequently the liquor is either boiled down to the point of solidification corre-
sponding to a density of 70 to 75° Be., or in case the small amount of potassium
chlorate contained in the chloride of zinc would be injurious, a quantity of
hydrochloric acid equivalent to the former, (6 equ. of HCl to 1 equ. of KClO3)
is added to the liquor, the latter slowly heated, boiled and finally brought to the
point of solidification.
The chlorine last obtained may be advantageously utilised. The chloride of
zinc produced by this process is extremely white and pure and suitable for any
industrial application.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is ;-
1. In the manufacture of potassium chlorate, the use of oxide of zinc, instead of
lime, substantially as described.
2. The method of recovering the whole of the chlorine used in the manufacture
of potassium chlorate, substantially as described.
Doted this 10th dex of Anril 1095
FAIRFAX & WETTER,
433, Strand, London, Agenta.