Improvements in the Manufacture of Chlorates, and in Means and Appliances therefor.
Year: 1895

page_text: Date of Application, 30th Aug., 1895
Complete Specification Left, 30th May, 1896-Accepted, 29th Aug., 1896
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Chlorates, and in Means and
Appliances therefor.
I JAMES HARGREAVES, of Farnworth-in-Widnes, in the County of Lancaster
Chemical Engineer do hereby declare the nature of this invention to be as
follows:-
My said improvements consist:-First, in exposing the materials used in the
manufacture of chlorates to the action of chlorine in the manner herein set forth.
The said materials after being chlorinated, I, for brevity and the purpose of this
specification, call "chlorinated products."
Second, I subject the said chlorinated products-in the manner herein set
forth to systematic limited selective lixiviation, which shall dissolve the more
soluble salts and leave the less soluble salts undissolved. The materials to be
used are preferably such as shall be the most economical-having regard also to
the cost of labour and fuel to be employed in obtaining the finished merchantable
chlorates.
The method of carrying my said invention into effect is varied as herein set
forth in such manner as to be adapted to the chemical and physical properties of
the materils used or employed in the said manufacture.
For example:-The soda requred in the manufacture of chlorate of soda can
be obtained at a low cost, and hence there is not as much economy effected in the
cost of raw materials as will compensate for the extra cost of fuel and labour
required for seperating the chlorate of soda from calcium salts. Therefore:-when
making chlorate of soda, I take soda-preferably in the form of carbonate, and
add water to it, so as to form a hydrated carbonate.
I make the said soda into a
pasty condition, or I make it into granular pieces or such forms or conditions as
will allow of the easy permeation of the mass by chlorine, I place the said soda
into suitable vessels or chambers, which may be in the form of absorbing towers,
into which the said soda is charged at the upper part and discharged at the lower
part of the said absorbing tower. The said absorbing tower may be fitted with
shelves or bearers, so arranged as to allow the materials to descend gradually,
without putting excessive pressure upon the materials at the lower part of the
said absorbing tower. Or I may use a series of vessels or chambers through
which the chlorine passes in succession until the available chlorine is absorbed.
The said chambers or vessels are arranged with suitable gas connections, so that
when the contents of one of the said chambers or vessels are sufficiently chlorinated,
the chlorinated products may be withdrawn, and the said chamber or vessel
recharged with raw materials; and then made the last chamber of the series.
The said chambers may be fitted with shelves or other devices for increasing the
surfaces exposed to the action of chlorine, or any of the numerous suitable forms of
revolving absorbing chambers or vessels may be employed.
The carbonate of soda is set forth herein as the most practicable form of soda
to be employed for the purpose aforesaid, but caustic soda or the bicarbonate of
goda may be employed without departing from the nature of my said invention.
Another example of the application of my said invention, with the variations
necessary to effect economical production, is hereinafter set forth for the manufacture
of chlorate of potash. To use carbonate of potash for the manufacture of chlorate

page_text: of potash in the manner hereinbefore set forth for using carbonate of soda for the
manufacture of chlorate of soda would be costly. Therefore, for the purpose of
economy, I use as small a quantity of potassium salt as is practicable, and employ
such a salt as shall supply the potassium in its cheapest form. For the aforesaid
purpose I employ potassium chloride to which is added hydrated magnesia or
hydrated lime in the proportions indicated by theory, or thereabouts.
expose the aforesaid mixture of potassium chloride, and lime or magnesia, to
chlorination in the manner hereinbefore set forth for the manufacture of chlorate
of soda.
I then
During the chlorination of the raw materials as hereinbefore set forth, it is at
times of advantage to moisten the chlorine and raise the temperature of the said
raw materials. For this purpose I pass a current of steam into any portion of the
apparatus where such moistening and heating may be required. If in conse-
quence of the too sudden absorption of chlorine the temperature is too high, I cool
the mass by any suitable refrigerating appliances or by the admission of air or
other diluting gas.
I vary the method of applying the systematic limited selective lixiviation
according to the relative solubilities of the chlorates and of the secondary products
with which the said chlorates or either of them are mixed. Where the chlorate is
the more soluble salt, as is the case when manufacturing chlorate of soda, I cause
the lixiviating fluid to pass in a limited quantity through a series of vessels
charged with the said chlorinated products, whereby the more soluble chlorate
is dissolved, and the greater part of the less soluble sodium chloride is left
undissolved. As the liquid passes into the more recently charged lixiviating
vessels, it becomes more and more saturated with chlorate, while much of the
sodium chloride which has been taken into solution is again thrown out of solution;
so that when the solution has passed through the series of lixiviating vessels it is
rich in chlorate of soda with a comparatively small proportion of sodium chloride.
Whereas the solubility of chlorate of soda increases with increase of temperature
in a greater ratio than does the solubility of sodium chloride, I lixiviate at a high
temperature. I remove the latter traces of chlorate remaining amongst the
undissolved sodium chloride by the use of bydro extractors or other suitable
means.
The chlorate of soda contained in the solution obtained as aforesaid, is seperated
by cooling and crystallization, and the mother liquor, or the salts therefrom is or
are returned to the lixiviating vessels aforesaid.
To
The chlorate of potash is less soluble than the calcium or magnesium chloride
present in the chlorinated products, produced during its manufacture.
seperate the said chlorate of potash, I use the same systematic limited selective
lixiviation, which is hereinbefore set forth. In consequence of its less solubility
the said chlorate of potash is in great part left undissolved; and a great part of
such chlorate of potash as is taken into solution is again thrown out of solution
the liquid becomes saturated with calcium or magnesium chloride. The
solubility of chlorate of potash increases rapidly with elevation of temperature, and
therefore, to retain the chlorate of potash in the lixiviating vessels; the said
lixiviating vessels and their contents are kept cool by means of suitable
refrigerating appliances, or by the use of ice instead of water for the purpose
of lixiviation.
as
The chlorate of potash which remains undissolved, is contaminated with
impurities. To seperate the said impurities the said chlorate of potash is
dissolved in hot water, and the said impurities are seperated. The solution is
allowed to crystallise, and the mother liquors employed for lixiviating fresh
chlorinated products.
In effecting the aforesaid systematic limited selective lixiviation, I do not confine
myself to any particular method of bringing the said chlorinated products and the
lixiviating fluid into contact. When the said chlorinated products are sufficiently
porous lixiviate by filtration, and where they are practically impervious 1

page_text: lixiviate by successive washing, and allowing the undissolved salts to settle, I use
the liquid from one lixiviating vessel to wash the chlorinated products in another
vessel which has been more recently charged and thus take up the more soluble
salt in greater quantity, at each succeeding vessel, and at the same time cause the
precipitation of the less soluble salts.
The methods of applying my said invention to the manufacture of chlorate of
soda and chlorate of potash, are herein set forth as examples. The same methods
are also applicable to the manufacture of other chlorates, such for instance as the
chlorates of lime, magnesia and baryta.
To economise fuel, I use the mother liquors remaining from the crystallization of
previous charges of chlorate, to supply the water used for the hydration of the
carbonate of soda, magnesia, lime, or other of the raw materials aforesaid, before
submitting the said raw materials to chlorination.
Dated the 29th day of August 1895.
JAMES HARGREAVES,
Farnworth-in-Widnes.
Improvements in the Manufacture of Chlorates, and in Means and
Appliances therefor.
1, JAMES HARGREAVES, of Farnworth-in-Widnes, 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 relates to the manufacture or production of chlorates by subjecting
raw materials, such as soda, which may be in the form of carbonate, potassium
chloride, and the like to the action of chlorine in such a manner that the more
soluble salts become dissolved, while the less soluble salts remain unaffected.
My improvements consist mainly first, in exposing the materials used in the
manufacture of chlorates to the action of chlorine in the manner herein set forth
(the said materials when chlorinated being for brevity's sake, and for the purpose
of this specification, called “chlorinated products"), and, secondly, in subjecting
the said chlorinated products to systematic, limited and selective lixiviation, which
shall dissolve the more soluble salts and leave the less soluble salts undissolved.
The materials used are, preferably, such as shall be the most economical, having
regard also to the cost of labour and fuel to be employed in obtaining the finished
merchantable chlorates.
The method of carrying my said invention into effect may be varied in such a
manner as to be adapted to the chemical and physical properties of the materials
under treatment.
The accompanying drawings illustrate apparatus adapted for use in carrying my
invention into effect.
Fig. 1 is a vertical section of an absorbing tower, arranged for employment in
the production of chlorate of soda, in which the materials are exposed to the action
cf chlorine and in which the systematic limited selective lixiviation herein before
referred to is accomplished.
Fig. 2 is a vertical section taken at right-angles to Fig. 1.
Fig. 3 is a horizontal section on the line 3-3 in Fig. 2.
Figs. 4 and 5 are views respectively similar to Figs. 1 and 2 of the apparatus
arranged for employment in the production of chlorate of potash.
Fig. 6 is a vertical section and Fig. 7 a corresponding plan illustrating an
alternative method of carrying out my invention with the use of a series of
chambers or vessels instead of an absorbing tower.

page_text: Fige. 8, 9 and 10 are enlarged detail views illustrating an inexpensive method of
constructing the absorbing tower; Fig. 8 being an elevation of a portion of the
tower, Fig. 9 a vertical section and Fig. 10 a horizontal section.
I will now proceed to describe my invention as applied by way of example in
the manufacture of chlorate of soda. The soda required in the manufacture of
chlorate of soda can be obtained at a low cost, and hence there is not as much
economy effected in the cost of raw materials as will compensate for the extra cost
of fuel and labour required for separating the chlorate of soda from calcium salts.
Therefore, when making chlorate of soda, I take soda-preferably in the form of
carbonate and add sufficient water thereto to form a hydrated carbonate. The
said soda may be made into a pasty mass or into solid form, or it may be used in
granular or crystal form or in such other forms or conditions as will permit of easy
permeation by chlorine. The mass of soda is then charged into an absorbing
tower A built of stone, brick or similar material; the said soda being charged at
the upper part, while the chlorinated products and the sodium chloride are
discharged at the lower part of the said absorbing tower. B is the chamber into
which the soda is charged. The lower part of the chamber is furnished with
transverse bearers C, preferably of prismatic form, so arranged as to allow the
materials to descend gradually and freely while allowing free circulation of gas;
these bearers tending to hold up the materials and only allow the sodium chloride
to fall into the chlorinating chamber D when the chlorinating is almost or entirely
complete. Additional adjustable bearers c may be placed below the bearers C if
it be found that the material passes too rapidly. The chlorine is admitted to the
chamber D by the pipe E and Alue E'; the gas passing partly into the compartment d
and through the grid d into the chamber D and partly over the wall d² of the flue
into the chamber D, where it acts upon any undecomposed soda remaining in the
sodium chloride falling from the bearers C. During the working of the apparatus,
the salt or sodium chloride, which remains undissolved in the chlorate liquor, is
collected in the chamber D, whence it may be periodically withdrawn through
openings d³, provided with doors, and removed to the floor F where it is allowed
to drain; the liquor therefrom running into the trough or gutter F. The chlorate
liquor issues from the compartment d' by way of the pipe G provided with a
regulating cock g and passes into a saturating tank H. This tank is divided into
three compartments h, 1, 12. The compartment is charged with pieces of soda
which rest on a grid or perforated bottom 3; the pipe G dipping well into the
mixture of soda and chlorate liquor in order to prevent the escape of chlorine gas,
while the pieces of soda absorb any excess of free chlorine present in the liquor.
The said chlorate liquor then passes into the compartment and thence over the
partition into the compartment /³. The liquor may now be conducted to con-
centrating pans and treated in the usual manner, or it may be raised by means of a
suitable pump I (Doulton's stoneware pump being the most suitable for the
purpose) and delivered by way of the pipe i into the tank a and a portion used in
assisting to dissolve the undecomposed soda in the upper part of the chamber B.
The liquor is allowed to flow from the tank a in a limited degree by way of the
pipe a furnished with a regulating cock a². Any small particles of soda which
may have come along with the liquor fall to the bottom of the tank a and are
carried through the pipe a¹ to the chamber B. A hose or other suitable appliance
(not shown) may be attached to the pipe a' for spraying the undecomposed soda
with the liquor. b is a pipe for conveying the liquor from the tank a to the con-
centrating pans. e is a stage from which the chamber B may be charged and
inspected. is the floor ordinarily used when discharging the chamber D. The
liquor in the gutter F1, resulting from the draining of the insoluble salt or sodium
chloride, may be transferred to the compartment 2 and conveyed thence with the
chlorate liquor into the tank a.
By subjecting the chlorate liquor to successive passages through the charge of
suda in the chamber B, soda possessing a lower degree of hydration may be used.
Moreover, with such a method of working, a much stronger liquor is produced,

page_text: with the result that the proportion of insoluble sodium chloride yielded in, the
chamber D is increased. The cost incidental to concentration is hereby reduced
and the amount of the salt which usually has to be eliminated from the
concentrating pans is minimised.
Openings which may be closed by glazed doors are provided for enabling
the working to be inspected, and also for permitting the insertion of tools for
breaking any hard lumps of soda. Through the openings the operator can
regulate the adjustable bearers c. dare similar glazed openings for inspecting
the compartment d' and removing therefrom any sodium chloride that may find its
way through the grid d.
Ordinary soda crystals may be used in the absorbing chambers, or the soda may
be prepared in the following manner:-The dilute liquors resulting from washing
the chlorate out of the salt may be employed for hydrating the soda. The latter
in the form of soda ash is ground under "edge-runners" and mixed in about the
proportion of 100 parts with 100 or 150 parts of weak liquor, by weight, the
mixture then being set aside to solidify. The quantity of water used may be
varied. Where only a small proportion of water is used, the progress of the
reaction is slow and a larger absorbing space is necessary. The chlorate liquors
resulting are, however, stronger in chlorate and will be found to contain a smaller
proportion of sodium chloride. When using soda in its less hydrated form, it is
preferred to cause a portion of the chlorate liquor to pass again through the soda
in the absorbing chamber B.
The salt removed from the chamber D after having been allowed to drain may
be transferred to a centrifugal hydro-extractor; steam and hot water being caused
to pass therethrough. The "fishings" of salt obtained from the concentration of
the chlorate liquor are washed with hot unconcentrated chlorate liquor, allowed to
drain and then they may be treated for the extraction of the remaining chlorate in
the same manner as described for treating the salt taken from the chamber D.
Instead of employing an absorbing apparatus as above described, I may use a
series of vessels or chambers, such as B, Figs. 6 and 7, through which the chlorine
is caused to pass in succession until all the available chlorine is absorbed. The
said chambers or vessels B' are provided with luted gas connections K, so that
when the contents of one of the said chambers or vessels are sufficiently chlorinated,
the chlorinated products may be withdrawn, and the said chamber or vessel
recharged with raw materials; the vessel thus recharged being made the last in
the series. The chambers may be fitted with shelves or other devices for
increasing the surface exposed to the action of chlorine, or any of the numerous
suitable forms of evolving absorbing chambers or vessels may be employed.
In Fig. 6, I have shown the chambers as provided with a false bottom or grid B²
whereon the materials to be treated rest. The chlorine enters the open space B³
by way of the opening k and after percolating the mass of soda passes out at the
opening k through the luted connecting pipe K to the next chamber of the series.
The chlorinated products may be pumped from one vessel to the next vessel of the
series.
Carbonate of soda as herein set forth is found to be the most practicable form of
soda for the purpose of this invention, but it will be understood that caustic soda or
bicarbonate of soda may be employed.
Referring to Figs. 4 and 5, in the application of the invention in the manufacture
of chlorate of potash, it may be observed that the use of carbonate of potash for
the production of chlorate of potash, in a manner similar to that set forth in using
carbonate of soda in the manufacture of chlorate of soda, would be costly. For
economical reasons, I therefore prefer to use as small a quantity of potassium salt
as is practicable, and employ such a salt as shall supply the potassium in its
cheapest form. Potassium chloride has been found most suitable for the purpose,
to which is added hydrated magnesia or hydrated lime in the proportions indicated
by theory, or thereabouts. The mixture of potassium chloride and hydrated lime
or magnesia is subjected to chlorination in a similar manner and in similar

page_text: apparatus to that described for use in the manufacture of chlorate of soda.
When readily obtainable, potassium sulphate may be used instead of potassium
-chloride..
For the manufacture of chlorate of potash by the employment of hydrated lime
or of hydrated magnesia and potassium chloride, in consequence of the pasty
impermeable character of the materials to be treated, it is necessary to furnish the
chamber B with a number of horizontal shelves or bearers B or their equivalent;
the sides of the chamber B being provided with plug-holes B³ through which the
working may be inspected and the materials stirred. The materials pass over
the transverse prismatic bearers C and in falling therefrom are acted upon by
the chlorine in a similar manner to that described with reference to Figs. 1, 2
and 3; the chlorate being yielded upon the grid d. The chlorate remains in great
part insoluble in the chamber D while the more soluble calcium chloride flows into
the tank H where the excess of chlorine contained in the solution is absorbed by
lime which is placed for that purpose in the compartment h. The lime may be
maintained in a state of agitation by any suitable means. The calcium chloride
solution along with any potassium chloride contained therein may be conveyed
from the compartment of the tank H to the tank a and caused to pass through
the materials forming the charge in the chamber or vessel B, and again subjected
to the action of the chlorine; the calcium or magnesium chloride liquors being
rendered stronger and the quantity of the chlorate deposited in the chamber D
considerably enhanced.
It is at times advantageous to moisten the chlorine and raise the temperature of
the raw materials with a view to rendering the reaction more rapid. For this
purpose a current of steam may be admitted at any suitable part (say at B6) of the
chamber B. If, in consequence of the ton sudden absorption of chlorine, the
temperature is too high, the mass may be cooled by any suitable refrigerating
appliances, or by admission of air or other diluting gas.
The chlorate of potash being the less soluble salt is left, as regards the greater
part, in the chamber D, whence it may be removed to the ground chamber F,
while the calcium chloride passes away by the pipe G. The calcium salts
contained in the chlorate of potash may be extracted by lixiviating with ice or
very cold water, when the chlorate of potash will be left practically pure (with the
exception of insoluble matters only). The said chlorate may then be refined by
any of the usual or well-known methods.
The method of applying the systematic limited selective lixiviation may be
varied according to the relative solubilities of the chlorates and of the secondary
Where the
products with which the said chlorates or either of them are mixed.
chlorate is the more soluble salt, as is the case when manufacturing chlorate of
soda, I cause the lixiviating liquid to pass in a limited quantity through a series of
vessels or through a very deep vessel charged with the chlorinated products; the
latter allowing of a deep layer of material through which the fluid passes;
whereby the more soluble chlorate is taken into solution while the less soluble
materials are left undissolved or deposited. In the case of making chlorate of
soda, the excess of chlorine held in solution at the end of the first lixiviation passes
through the soda contained in the tank H whereby the solution is still further
enriched with chlorate of soda. As the liquid is repeatedly passed through the
materials in the vessels, it becomes more and more saturated with chlorate, while
much of the sodium chloride which has been taken into solution is again thrown
out of solution; so that the solution becomes very rich in chlorate of soda with a
comparatively small proportion of sodium chloride.
In the case of chlorate of potash, the solution becomes richer in calcium chloride,
while the chlorate of potash is left insoluble.
Lixiviation and chlorination as herein described may be conducted at a high
temperature, but I have found that on the whole it is not advantageous to heat
the chambers when making chlorate of soda. The temperature should not be so
high as to liberate much oxygen. I remove the latter traces of chlorate remaining

page_text: amongst the undissolved sodium chloride by the use of hydro-extractors or other
suitable means.
The ehlorate of soda contained in the solution obtained as aforesaid is refined by
concentration; the mother liquor or the salts therefrom being returned to the
lixiviating vessels.
The chlorate of potash as herein before stated is less soluble than the calcium
or magnesium chloride present in the chlorinated products, produced during its
manufacture. To separate the said chlorate of potash, I use the herein described
systematic limited selective lixiviation. In consequence of its less solubility the
chlorate of potash is in great part left undissolved; and a great part thereof which
is taken into solution is again thrown out of solution as the liquid becomes
saturated with calcium or magnesium chloride. The solubility of chlorate of
potash increases rapidly with elevation of temperature and therefore, to retain
the chlorate of potash in the lixiviating vessels, the said lixiviating vessels and
their contents are or may be kept cocl by means of suitable refrigerating appliances,
or by the use of ice instead of water for the purpose of lixiviation.
The chlorate of potash which remains undissolved is contaminated with impurities.
To separate the said impurities, the said chlorate of potash is dissolved in hot
water, and the said impurities are separated. The solution is allowed to crystallize
and the mother liquors utilized in lixiviating fresh chlorinated products.
In effecting the aforesaid systematic limited selective lixiviation, I do not confine
myself to any particular method of bringing the said chlorinated products and the
li
ating fluid into contact. When the said chlorinated products are sufficiently
ous, I lixiviate by filtration, and when they are practically impervious, I lixiviate
When working
y successive washings and allow the undissolved salts to settle.
with a series of vessels, I use the liquid from one lixiviating vessel to wash the
chlorinated products in another vessel which has been more recently charged, and
thus take up the more soluble salt in greater quantity, at each succeeding vessel,
and at the same time cause the precipitation of less soluble salts.
The herein described methods of applying my said invention are given as
examples only. The same methods may be applied in the manufacture of other
chlorates; such for instance as the chlorates of lime, of magnesia and of baryta.
To economise fuel, I use the mother liquors remaining from the crystallization of
the previous charges of chlorates to supply the water used for the hydration of the
carbonate of soda, magnesia, lime, or other of the raw materials aforesaid, before
submitting the said raw materials to chlorination.
It will be understood that the herein described methods of converting soda and
potash into chlorates may be reversed, provided the cost of the materials be
favourable to such course; the sodium chloride being mixed with lime and then
converted into chlorate of soda, or carbonate of potash may be treated directly
with chlorine, for the manufacture of chlorate of potash.
In Figs. 8, 9 and 10, I have illustrated an economical method of constructing
and bracing the absorbing tower or chamber. A wall A of brick is enclosed by
slabs of slate A³, a filling of cement A³ occupying the space between the brick and
the slate. The bracing is accomplished by means of angle-iron A4, A', secured by
bolts A, preferably arranged as shown in Figs. and 9; the angle-irons As
centring over the joints of the slate slabs A2 and having their inner angles filled
with cement A. A firm gas-tight bedding is thus presented at the junction of the
slate slabs.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, 1 claim :-
1. In the manufacture of chlorates, subjecting the raw materials, in the form of
crystals or otherwise, to the action of chlorine and simultaneously to lixiviation,
with the effect that the more soluble salts become dissolved whilst the less soluble
salts remain undissolved.
2. In the manufacture of chlorate of soda, the treatment of hydrated carbonate

page_text: of soda by lixiviation in the presence of chlorine substantially as herein described,
whereby the chlorate or soluble matter is taken into solution whilst the less soluble
matter or sodium chloride is left undissolved.
3. In the manufacture of chlorate of potash, the treatment of potassium chloride
mixed with hydrated lime or hydrated magnesia by lixiviation in the presence of
chlorine substantially as herein described, whereby the soluble chlorides are taken
into solution whilst the insoluble matter or chlorate is left undissolved.
4. In the manufacture of chlorates by lixiviating the raw materials in the
presence of chlorine, the employment of apparatus arranged substantially as
described with reference to Figs. 1, 2 and 3 of the accompanying drawings, and
comprising a chamber, such as B, having at its lower end bearers such as C, a
chamber D into which chlorine is admitted and in which the insoluble salt is
deposited, and a tank H into which the solution containing the soluble salt or
chlorate is run, and the excess of chlorine absorbed, and whence the solution may
be removed either to concentrating pans or for use in lixiviating fresh charges
of soda.
5. In the manufacture of chlorates by lixiviating the raw materials in the presence
of chlorine, the employment of apparatus arranged substantially as described with
reference to Figs. 4 and 5 of the accompanying drawings, and comprising a
chamber such as B furnished with shelves or carriers B, and having at its lower
end bearers such as C, a chamber D into which chlorine is admitted and in which
the insoluble salt or chlorate is yielded, and a tank H, into which the solution
containing the soluble salt or calcium chloride is run, and any free chlorine is
absorbed, and whence the solution may be removed for use in lixiviating fresh
charges of raw material.
6. In the manufacture of chlorates by lixiviating the raw materials in the presence.
of chlorine, the employment of a series of vessels, such as B', provided with gas
connections, such as K, arranged or operating substantially as described with
reference to Figs. 6 and 7 of the accompanying drawings.
Dated this 30th day of May 1896.