Improvements in the Treatment of Manganates for the Production of Permanganates suitable for use for Disinfecting or other Purposes, and in Apparatus therefor.
Year: 1893

page_text: Date of Application, 19th Jan., 1893
Complete Specification Left, 13th Oct., 1893-Accepted, 18th Nov., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Manganates for the Production
of Permanganates suitable for use for Disinfecting or other
Purposes, and in Apparatus therefor.
I WILLIAM JONES MENZIES of Stretton Hall Malpas in the County of Chester
a Director of The United Alkali Company do hereby declare the nature of this
invention to be as follows :--
It is well known that permanganates are excellent disinfectants and oxidizing
agents but their high price has hitherto been an obstacle to their general application.
The cheaper manganates of soda have been successfully employed in the disinfection
of rivers and town sewage, but the necessity of using sulphuric acid in conjunction
with such manganates is for many applications (particularly for household use) a
serious hindrance to their use. Many attempts have been made to render the cheap
manganates more available for general use by mixing with them various ingredients
such as acid salts or boric acid or the like, but such mixtures are almost if not
quite as corrosive as is the sulphuric acid. The manganates as produced for
commerce also contain a large quantity of caustic soda which is a further objection
to their use for general disinfecting or oxidizing purposes.
According to my invention I neutralize the caustic soda contained in commercial
manganates of soda with carbonic acid and convert the manganate into a per-
manganate by the action of carbonic acid.
I may add the carbonic acid in the form of a bicarbonate preferably bicarbonate
of soda. Or I may add the carbonic acid in the form of gas derived from any
available source for instance from liquid carbonic acid or by producing it in any
well known manner for example by treating limestone with hydrochloric acid or I
may use the washed gases from a lime kiln or similar dilute carbonic acid' from any
operation which produces it sufficiently pure may be used.
1 charge a vessel or chamber with the manganate of soda preferably in a
pulverulent condition and cause the carbonic acid gas to act upon it. The carbonic
acid gas is rapidly absorbed with evolution of heat and the manganate is converted
into permanganate and any excess of caustic soda contained in the mangannte is
converted into a carbonate. Care must be taken not to allow the temperature to
rise too high which may be done by regulating the flow of carbonic acid or by
cooling the surface of the vessel containing the manganate in any suitable manner
for instance by applying cold water.
.
The apparatus may consist of a chamber having shelves or trays within it upon
which the manganate may be spread in layers suitable openings being provided for
charging the trays and withdrawing the finished material and also for the admission
of the carbonic acid gas and for permitting the exit of air or inert gases which
may be contained in the carbonic acid gas. To accelerate the action and expose
new surfaces of the manganate to the carbonic acid gas I may stir or agitate the
material from time to time by hand or by a mechanical stirrer for example. Or
the apparatus may cousist of a horizontal or approximately horizontal revolving
cylindrical vessel provided with an opening (capable of being closed) for charging
the manganate and for withdrawing the permanganate. The carbonic acid gas can
be introduced into the vessel or cylinder through hollow trunnions. The said
cylinder may be provided with a mechanical stirring appliance.
In order to regulate the temperature I may cool the outside of the cylinder or
the chamber with water. Or may cause a rapid circulation of the
gas between
the cylinder and a cooling apparatus propelling the gas by a fan in such manner
that the hot gas is drawn from the cylinder or chamber forced through the cooling

page_text: apparatus and afterwards back again into the cylinder or chamber. The cooling
apparatus consists of a pipe or pipes surrounded by a cooling or refrigerating
medium such as cold water or refrigerated brine or of a chamber through which
the gas passes the said chamber being traversed by pipes through which a cooling
or refrigerating medium. such as cold water or refrigerated brine flows continuously
or intermittently.
The cooling apparatus must be provided with an outlet for, condensed water
situated at the lower part of the cooling apparatus and below the inlet or outlet
pipe of the apparatus.
The permanganate obtained according to my invention is a dry powder and inay
if not fine enough be ground. It can be sold in this form and may be applied in
all processes for which permanganates have hitherto been required if great purity
is not requisite.
.
Or the permanganate may be dissolved in water and the filtered or settled
solution may be sold or used.
Dated this 19th day of January 1893.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London.
COMPLETE SPECIFICATION.
Improvements in the Treatment of Manganates for the Production
of Permanganates suitable for use for Disinfecting or other
Purposes, and in Apparatus therefor.
1, WILLIAM JONES MENZIES of Stretton Hall, Malpas in the County of
Chester, a Director of The United Alkali Co. Ltd. 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 well known that permanganates are excellent disinfectants and oxidising
agents but their high price has hitherto been an obstacle to their general application.
The cheaper manganate of soda has been successfully employed in the disinfection
of rivers and of town sewage, but the necessity of using sulphuric acid in conjunction
with such manganates is a serious hindrance in many applications particularly for
domestic use. Many attempts have been made to render this cheap manganate
more available for general use by mixing it with various ingredients such as acid
salts, boric acid, or the like, but such mixtures are almost as corrosive as is the
sulphuric acid. The commercial manganate of soda also contains a large quantity
of caustic soda which is an objection to its general application.
According to my invention I neutralise with carbonic acid the caustic soda
contained in commercial manganate of soda and convert the manganate into per-
manganate by the action of carbonic acid.
I may add the carbonic acid in the form of bicarbonate of soda. The quantity
of bicarbonate of soda necessary depends largely upon the composition of the
particular manganate of soda to be treated but I prefer to mix one part of manga-
nate of soda with at least one part, preferably more (say 1 parts) of bicarbonate.
I mix the two salts intimately by grinding them together in an ordinary mill or
otherwise. The dry mixture is then ready for sale.
Or I may add the carbonic acid in form of gas derived from any available source,
for instance from liquid carbonic acid or by producing it in any well known
manner for example by treating limestone with hydrochloric acid, or 1 may use the
gases from a lime kiln previously washing them with water to remove therefrom
any tarry matter or any sulphurous acid which may be contained therein. Or
dilute carbonic acid gas from any source may be used, provided that it be free
from substances which would injuriously affect the manganate or the permanganate
to be produced.
I charge a suitable chamber or vessel with manganate of soda preferably in a

page_text: pulverulent condition and cause the carbonic acid gas to act upon it. The carbonic
acid gas is rapidly absorbed with evolution of heat, particularly in the presence
of moisture and the manganate is converted into the permanganate. Any excess
of caustic alkali contained in the manganate is converted into carbonate or
bicarbonate of the alkaline base. Care must be taken not to allow the temperature
to rise too high, which may be accomplished by judiciously regulating the flow of
carbonic acid gas as by cooling the surface of the chamber or vessel containing the
manganate in any suitable manner, for instance by applying cold water.
The apparatus, may consist of a closed chamber made of iron having shelves or
trays within it, upon which the manganate may be spread in layers. The chamber
must be provided with suitable openings capable of being closed, and through
which the trays (when trays are used) may be introduced when charged with
manganate, and withdrawn when the manganate has been converted into per-
manganate. The chamber must also have apertures for the admission of the
carbonic acid gas, and for the escape of air or of any inert gases which may be
contained in the carbonic acid gas. In order to accelerate the action of the gas
upon the manganate, and to expose new surfaces of the manganate to the gas I
may stir or agitate the material from time to time. This may be done by hand,
but preferably continuously by means of a mechanical stirrer.
I prefer to use an apparatus consisting of a horizontal or approximately
horizontal cylindrical vessel capable of being rotated so as to agitate the
manganate continuously. Such an apparatus is illustrated in side elevation end
view and plan respectively in Figures 1, 2 and 3 of the accompanying drawings.
The cylinder A (which may be made of steel plate for instance) is provided
with hollow trunnions or axes supported by and capable of turning in bearings a
carried by a framework. The hollow axis at one end of the cylinder is used for
admitting carbonic acid gas and that at the other end is used for permitting the
exit of any air or inert gas as well as any superfluous moisture. The hollow axles
are continued into the interior of the cylinder and turn upwards as shewn at bin
Figure 1 for the purpose of avoiding the lodgment therein of solid material and the
consequent stoppage of the free passage of the gas into or from the cylinder. I
find it advisable to have apertures at ee in the cylinder A and exit pipe C
respectively which can be closed air tightly in any convenient manner and through
which when necessary the part of the exit pipe C which is inside the cylinder A
may be cleaned easily and freed from dust which is sometimes deposited there.
The aperture e at the pipe C serves also to permit the escape of inert gases from
the interior of the cylinder A when required. Outside the cylinder A the exit
pipe C leads to a fan F which exhausts the gas and propels it through a cooling
apparatus D and afterwards back again into the cylinder A through a pipe d
joining the carbonic acid supply pipe Y.
The cylinder A is provided with openings for inserting the manganate and with-
drawing the permanganate, close covers being provided to fit over these openings.
The charge of manganate is introduced into the cylinder A, the opening is then
closed and the cylinder made to rotate slowly which may be done by means of a
pulley H shaft and spur gearing G driven by any suitable motor. find from
two to six rotations per minute are sufficient. When carbonic acid gas is admitted
into the interior of the cylinder A by the pipe Y the temperature of the manganate
rises and the carbonic acid gas is rapidly absorbed by the charge. The progress of
the operation may be ascertained by withdrawing and testing a sample from time
to time. When absorption ceases the temperature falls and the finished
permanganate may be withdrawn from the cylinder and may afterwards be ground,
when it is ready for sale.
In case the temperature rises too rapidly I regulate it by cooling the outside of .
the cylinder with water. Or I prefer to cause a rapid circulation of the gus
between the cylinder A and a cooling apparatus D by means of the fan F in such
manner that the hot gas is drawn from the cylinder or chamber, forced through the
cooling apparatus and back again into the cylinder. The cooling apparatus D

page_text: may be simply a pipe surrounded with cold water, or it may consist of several such
pipes. As shewn at D in Figure 1 it is a chamber through which the gas passes
on its way from the fan F to the cylinder A. Through the interior of this
chamber pass pipes connected at the bottom with a supply chamber, and at the top
a delivery chamber. Through these pipes a steady flow of cold water (or if
necessary refrigerated brine) is maintained. The water or brine enters at w, and
flows off at w. During the passage through this apparatus the gas is cooled, and
some water is condensed which is permitted to flow away at
An outlet for
condensed water is also provided at the bottom of the outlet pipe C, as shewn at x
and on a larger scale in Figure 4.
When
By these means the temperature in the cylinder A can be controlled.
dilute carbonic acid gas is employed I employ a series of such cylinders, causing
the gas to enter a first one, and leaving this to pass into a cooling apparatus and
then into a second absorbing cylinder and so on.
When the cylinder and its contents have become cool, and shew no further signs
of heating the permanganate is withdrawn. After grinding it to the requisite
fineness it may be sold.
Or the permanganate may be dissolved in water and the solution sold as a
disinfecting fluid or otherwise utilised.
I have mentioned more particularly manganate of soda as being the manganate
treated but other manganates such as manganate of potash may be treated in the
manner described if desired.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. The treatment of manganates for the production of permanganates by
subjecting the manganates to the action of carbonic acid gas substantially as
herein before described.
2. The conversion of manganates into permanganates by admixture therewith of
bicarbonates substantially as hereinbefore described.
3. The treatment of manganate of soda for the production of permanganate of
soda by subjecting the manganate to the action of carbonic acid gas substantially as
hereinbefore described.
4. The conversion of manganate of soda into permanganate of soda by admixture
therewith of bicarbonate of soda substantially as hereinbefore described.
5. The apparatus for treating manganates with carbonic acid gas for the purpose
of producing permanganates the said apparatus being arranged substantially as
hereinbefore described and illustrated by the accompanying drawings.
6. In the treatment of manganates with carbonic acid the means of regulating
the temperature by cooling apparatus substantially as herein before described and
shewn in the accompanying drawings.
Dated this 13th day of October 1893.
J. H. JOHNSON & Co.,
Agents.