Year: 1886

page_text: Date of Application, 6th Nov, 1886
Complete Left, 18th June, 1887.
Complete Accepted, 19th July, 1887.
I, JOSIAH WYCKLIFFE KYNASTON of Kensington, in the City of Liverpool,
Manufacturing Chemist, do hereby declare the nature of this invention to be as
follows:-
In the process of manufacture most commonly used for the production of chlorate
of potash, after the bulk of the chlorate has been crystallised out from the chloride of
calcium solution, there still remains a considerable quantity, amounting to from 12
to 15 per cent. of chlorate of potash which is practically irremovable from the chloride
of calcium by further concentration of the solution, and these mother liquors have
therefore been allowed to run to waste, though containing about 20 ounces of
chlorate of Potash in each cubic foot.
In order to avoid this loss it has been proposed to extract a part of the calcium
chloride during the process of manufacture by adding lime to the mixed solution of
chloride of calcium and chlorate of lime, and heating to near boiling point; on again
cooling, oxychloride of calcium crystallises out, and can be separated.
Only a small part of the chloride of calcium can be separated this way without
chlorate of lime being precipitated with it, and consequently only a small quantity of
the residual chlorate can be saved, whereas by my improvements practically the whole
of the chlorate can be separated.
My invention consists mainly in operating with lime upon the residual liquors after
treating with chloride of potassium instead of before that operation. To accomplish
this I first add to the liquor to be treated, which usually tests about 65 degrees
Twaddle, about two fifths of its bulk of water, and heat to boiling. I then add slacked
lime in the proportion of one and one half equivalents for each equivalent of chloride
of calcium contained in the liquor, at the same time agitating the mixture and
maintaining a boiling temperature for a short time, after the whole of the lime has
been stirred in. A further quantity of water equal to about four fifths of the bulk
of chlorate liquor treated is then added with continued agitation. By this treatment,
one half of the chloride of calcium present is converted into the oxychloride of
ID 077

page_text: calcium, which, in the presence of the excess of chloride of calcium, is a permanent
and nearly insoluble salt.
The mixture is run down to cooling tanks, and when quite cold the mass of crystals
is broken up, and the whole passed on to a filter bed, and when the liquor has drained
away, a quantity of water equal to the original bulk of liquor treated is run upon the
crystals to wash them, and the washings are also drained through. The liquor and
washings are then concentrated to one half the bulk occupied by the original liquor
treated, and on cooling one half the chlorate of potash contained in the original liquor
crystallises out, and is purified by washing and re-crystallisation in the usual ways.
The mother liquor from these crude crystals is mixed, with an equal bulk of
original chlorate liquor, and the treatment with lime repeated exactly as before.
The crystalline mass of calcium, oxychloride when heated to boiling with water, is
decomposed, chloride of calcium passes into solution, and on standing, the lime is
deposited in a condition available for the treatment of fresh portions of liquor, or it
may be advantageously used instead of fresh lime in the Weldon process for the
production of the chlorine required in the manufacture of chlorate or of bleaching
powder.
Dated this 5th day of November 1886.

page_text: COMPLETE SPECIFICATION.
Improvements in or relating to the Manufacture of Chlorate of
Potash.
I JOSIAH WYCKLIFFE KYNASTON of Kensington in the City of Liverpool
Manufacturing Chemist, 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:
In the process of manufacture in common use for the production of chlorate of
potash, by passing chlorine into milk of lime mixed with chloride of potassium in
excess, or into milk of lime alone, and the addition, after saturation with chlorine, of
chloride of potassium, there is obtained a solution containing chlorate of potash, and
for each equivalent of this salt, there are present five or six or more equivalents of
chloride of calcium, and also a quantity of undecomposed chloride of potassium, the
latter salt being required to be used in considerable excess of the quantity actually
required to form chlorate of potash.
The concentrated solution at about 65 degrees Twaddle being set aside to crystallise,
deposits the greater part of the comparatively little soluble chlorate of potash. If it
be attempted to further concentrate the liquors, chlorate of potash and chloride of
calcium crystallise out together, and it has not been found possible to separate the
two salts and therefore the mother liquors, nearly saturated with chloride of calcium,
and containing from 12 to 15 per cent. of the whole chlorate of potash originally
present and all the excess of chloride of potassium used, have hitherto been allowed to
run to waste.
It has been proposed in a previous invention to avoid this loss of chlorate of potash
by treating the solution obtained by passing chlorine in excess into milk of lime, so as
to reduce the proportion of chloride of calcium to the chlorate of lime present, and
before the addition of the chloride of potassium to produce the less soluble chlorate of
potash, but when one of the processes, namely, the treatment of the solutions with
lime so as to produce oxychloride of calcium, is used, the oxychloride being formed in
the presence of so much chlorate the latter is enclosed by, and adheres to, the
oxychloride with such tenacity, that very considerable loss of chlorate takes place, and
the relative proportions of chloride and chlorate remaining in solution are not greatly
altered, and the process has not been put in operation.
When however, the greater part of the chlorate has been separated as in the
ordinary course of manufacture of chlorate of potash, the chloride of calcium may
then be more advantageously removed from solution, and my invention consists in
treating the residual mother liquors, after the separation of the greater part of the
chlorate of potash by the usual process of crystallisation, with lime in such manner
that the whole chloride of calcium is eventually removed from solution almost freed
from chlorate and from eighty to ninety per cent. of the chlorate of potash and nearly
the whole of the excess of the chloride of potassium used is recovered.

page_text: Crystallised oxychloride of calcium, the chemical formula for which is, 3 Ca O,
Ca Ci,, 15 H, O, is an unstable salt when in contact with pure water, and equally so
in solution of chlorate of potash or chloride of potassium, and if it be attempted to
remove the whole chloride of calcium from such solutions by the addition of sufficient
lime to convert it into oxychloride, the process entirely fails to accomplish the end in
view. When a certain quantity of oxychloride has been formed, the remainder of the
lime refuses to enter into combination with the remaining chloride of calcium, and the
result is an unmanageable mixture of oxychloride, and free hydrate of lime suspended
in solution of chloride of calcium. But in a solution of chloride of calcium of
sufficient strength, oxychloride of calcium is a perfectly stable, definitely crystallised
salt, and the whole of the lime used in the formation of the oxychloride is rendered
available.
In carrying out this invention therefore, 1 treat the chlorate of potash mother
liquors with slaked lime in sufficient quantity only to convert one-half of the chloride
of calcium present into oxychloride. When quite cold the solution of chloride of
calcium, which when reduced by concentration to its original bulk is only of one-half
the strength it was at the commencement of the operation, but containing nearly the
whole of the chlorate of potash, and chloride of potassium originally present, is drained
off and concentrated to one-half its original bulk, and allowed to cool when it deposits
one half the chlorate of potash, and chloride of potassium. The liquor is drained from
these crystals, mixed with an equal bulk of fresh mother liquor and the treatment
with lime repeated exactly as before described. The crystals of oxychloride of
calcium are treated with water, and the mixture is raised to the boiling point, when
the oxychloride is completely decomposed into chloride of calcium, which passes into
solution, and hydrate of lime which settles down. The solution of chloride of calcium
is drawn off and run away; the hydrate of lime, which should be again washed with
water is used for the treatment of fresh mother liquor for the separation of its chlorate
andchloride of potassium.
The apparatus in which the process is conveniently carried on and the mode of
working is as follows:
First, an iron vessel or tank fitted with a mechanical agitator, and of such capacity
that it will hold nearly three times the bulk of mother liquor to be treated in each
operation. Thus, for the treatment of 500 cubic feet of mother liquor, which is a
convenient quantity for the operation, the vessel should hold from 1400 to 1500 cubic
feet, and it is advisable that there should be provided two such vessels, to be worked
alternately. Into one of these vessels is pumped 500 cubic feet of mother liquor, just
as run from the chlorate crystallising cones, and into it steam is then blown, to raise
it to near the boiling point, and as much water added as will raise the whole to about
750 cubic feet. The agitator is then started, and slaked lime is gradually thrown in
until the quantity calculated to convert one-half the chloride of calcium in the batch
into oxychloride has been added. For 500 cubic feet of average liquor of about
65 degrees Twaddle will be required about 90 hundred weights of quick or unslaked
lime. After the addition of the lime, the agitation is continued for about a quarter
of an hour, and then a further quantity of 400 cubic feet of water run in, and the
agitation is continued until the whole is thoroughly mixed, and homogeneous. The
batch is then run off to
Second, a shallow iron cooler, not over 18 inches deep, and of such capacity that it
will hold the whole batch at about 14 inches in depth. If not of greater depth than
this the mass crystallises and cools the more quickly. When quite cold, the thick
mass of small crystals is broken up, when it becomes a thick liquid, and is passed
through a pug mill, or some similar arrangement by which any crystalline nodules
may be disintegrated, and from this it is allowed to run on to
Third, a filter bed of any ordinary construction, where the mass is allowed to drain
thoroughly. The liquor now draining through will be about the same bulk as that of
the mother liquor originally taken, or about 500 cubic feet. An equal bulk of cold
water is now run gradually on to the crystalline mass, and allowed to drain through.
The liquors so obtained are now boiled down in the ordinary concentrating pots

page_text: until a density of about 65 degrees Twaddle is attained, and then drawn off to the
crystallising cones in which the chlorate of potash and chloride of potassium separate,
and are purified by the ordinary well known means. The mother liquor from these
crystals is used for the next operation together with an equal bulk of fresh mother
liquor exactly as before described.
The mass of crystals of oxychloride of calcium is transferred from the filter bed to
the second of the agitating vessels before described. But first, some water is run in,
and steam is blown in continuously until the whole of the oxychloride has been added.
The oxychloride is now decomposed, hydrate of lime separates, and on standing at
rest quickly settles out, and the solution of chloride of calcium is drawn off and run
away. Water is then again added, to free the lime more perfectly from chloride of
calcium.
The fresh batch of chlorate mother liquor is now pumped into the agitator
containing the deposit of lime obtained by the decomposition of the oxychloride,
and the operation repeated exactly as before described.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I wish it to be understood that. Í
do not bind myself to the exact details of working as above described, but that what
I claim is
1st. The improved process for the manufacture of chlorate of potash, which
consists in passing chlorine into milk of lime, adding a potassium salt, and separating
the crystals in the manner well known, then adding lime and water to the mother
liquor in sufficient quantity only to convert about half the chloride of calcium into
oxychloride of calcium, heating the mixture, separating the crystals, and evaporating
down the liquor to near the limit where chloride of calcium begins to crystallise out,
cooling and thus obtaining a fresh crop of chlorate, then adding the remaining mother
liquor and the drainings of the crystals to a fresh batch of the first mother liquor for
similar treatment, in the meantime decomposing the oxychloride of calcium so as to
obtain the lime applicable for the production of more oxychloride of calcium,
substantially as described.
2nd. The improvement in the manufacture of chlorates, which consists in the
recovery of the hitherto wasted chlorate of potash from the mother liquors of that
manufacture, by treating the liquors with slaked lime, so as to remove the chloride of
calcium as oxychloride, and permit of the further concentration of the liquors,
substantially as described.
Dated this 17th day of Lu 1007