IMPROVEMENTS IN THE MANUFACTURE OF PROVISIONAL SPECIFICATION
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
PROVISIONAL SPECIFICATION left by the said Walter Weldon at the Office
of the Commissioners of Patents on the 7th March 1881.
WALTER WELDON, of Rede Hall, Burstow, in the County of Surrey.
IMPROVEMENTS IN THE MANUFACTURE OF CHLORINE."
The method of manufacturing chlorine which constitutes the present Invention
consists in the following series of operations:-
First. A portion of the solid residual product of the third operation to be
described below is dissolved in hydrochloric acid. Chlorine is evolved, and there
is at the same time produced a solution of chloride of manganese.
Second. The solution of chloride of manganese produced in the first operation is
evaporated to a high degree of concentration, and is then mixed with a portion of
the solid residual product of the third operation, and the mixture is formed into
cakes, balls, briquettes, or other small pieces, such that when charged into a suitable
apparatus air and other gases shall be able to penetrate into and pass through the
interstices between them.
Third. The cakes, balls, or birquettes formed in the second operation are heated
in contact with a current of air. Chlorine is thereby driven off from them, and the
solid product which remains consists of a compound of binoxide of manganese with
manganese protoxide. A portion of this product is then used for a repetition of
the first operation, and the other portion for a repetition of the latter part of the
second operation.
The chlorine obtained by the first operation is of course unmixed with other
gases; but that obtained by the third operation is mixed with nitrogen and
excess of air, and may also have associated with it a little vapour of hydrochloric
acid. Any vapour of hydrochloric acid which may thus be contained in the gaseous
current from the third operation must be condensed out therefrom, as will be well
understood, before the gaseous current is treated for the utilization of its free
chlorine.

page_text: It will in some cases be necessary to dry the cakes, balls, or briquettes formed
in the second operation before subjecting them to the third operation.
The said third operation may be conducted by applying heat directly to the
exterior of the apparatus in which the operation is performed, and admitting
thereinto either cold or only partially heated air; but I prefer to dispense with
such external heating of the apparatus, and to heat the charge simply by treating
it with air, previously so bighly heated as to be capable of raising the charge to
the temperature at which the required reaction can take place.
The third operation may be conducted either intermittently or continuously;
but I prefer to conduct it in the continuous manner and by means of the
apparatus forming the subject of another Invention, an application for a Patent
for which will be filed on the same day as these presents.

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 25th August
1881.
WALTER WELDON, of Rede Hall, Burstow, in the County of Surrey.
"IMPROVEMENTS IN THE MANUFACTURE OF CHLORINE."
This Invention consists in manufacturing chlorine by the following series of
operations:-
First. A portion of the solid residue of the fourth operation to be described
below is dissolved in aqueous hydrochloric acid. The said solid residue contains
both peroxide of manganese and manganese protoxide, and will hereinafter bo
called manganite of manganese. The reaction of this body upon aqueous hydro-
chloric acid liberates therefrom chlorine gas, and at the same time produces a
residual solution of chloride of manganese.
Second. The aforesaid residual solution is evaporated to a high degree of
concentration.
Third. The concentrated solution from the second operation is mixed with
manganite of manganese from the third operation, and the mixture is formed into
cakes, cylinders, balls, or other small masses, such that when charged into a suitable
apparatus, air and other gases can penetrate into and pass through the interstices
between them.
Fourth. The cakes, cylinders, balls, or other small masses which have been formed
as just said are heated in a current of air. A part of the oxygen of the current of
air reacts upon the chloride of manganese contained in them, and transforms it
into manganite of manganese, at the same time driving off the chlorine of the said
chloride, mainly in the free state, but partly as vapour of hydrochloric acid. The
cakes or other small masses, which at the commencement of this operation were a
mixture of manganite of manganese with chloride of manganese, at the end of it
thus consist wholly of manganite of manganese, a part of which is then used
for a repetition of the first operation, and the other part for a repetition of the
third operation.
The first operation above described may be performed in a variety of ways, and
no particular manner of performing it constitutes any part of the present Invention.
It must be so performed however that the acid shall be completely neutralized by
the manganite of manganese. To this end, towards the latter part of the operation,
an excess of manganite of manganese must be employed. Those last portions of
the acid which would not dissolve peroxide of manganese will then be neutralized
by the protoxide of manganese contained in the excess of manganite; but the
resulting neutral solution will have suspended in it undissolved peroxide of
manganese, and probably unattacked manganite also. These must be allowed to
settle out before the solution is evaporated, and what has so settled out, after the
clear solution has been decanted or otherwise separated from it, should preferably
be dissolved in the next charge of hydrochloric acid before fresh manganite of .
manganese is added thereto. The earlier part of this first operation must necessarily
take place in chlorine stills, as will be well understood; but, when the free acid
remaining has become so dilute as to be incapable of dissolving more peroixde of
manganese, and so incapable of yielding more chlorine on more manganite of
manganese being added to it, the neutralization of this last part of the acid by
means of the protoxide contained in an excess of manganite may be performed
either in the chlorine stills themselves or in separate vessels. In the latter case
the apparatus used for the neutralization by excess of manganite may be the same
as that which is employed for the neutralization by carbonate of lime of the acid

page_text: still-liquors of the present Weldon process; and the mode of procedure will be
just the same as that followed in the operation just referred to, except that
manganite of manganese will be used as the neutralizing agent instead of carbonate
of lime.
The second operation above described may also be performed in many ways, and
in its case likewise no particular manner of performing it constitutes any part of
the present Invention. It may be performed in iron vessels, which the solution to
be evaporated will not materially attack if care have been previously taken that
it be perfectly neutral.
As regards the third and fourth operations which are described above, I do not
confine myself to any particular method of performing them, since they may be
performed in various ways, and no particular manner of performing them constitutes
any part of the present Invention. I will proceed however to set forth those
methods of performing them which I believe to be the best.
The aforesaid third operation may be carried out as follows:-A shallow cast-iron
vessel with a flat bottom is placed near the pan or other vessel in which the solution
of chloride of manganese is evaporated. The dispositions are such that concentrated
solution from the evaporating-vessel may be run into the flat-bottomed mixing vessel
at will. Solid manganite of manganese is placed in the mixing vessel, preferably in
the state of powder, and concentrated solution from the evaporating vessel is then run
into the mixing vessel, a workman meanwhile stirring the contents of that vessel
with a suitable rake. The solid matter will drink up the concentrated solution
the more readily if heat be applied under the mixing vessel so as so keep its contents
at or above the temperature of the boiling solution. The proportion of manganite
of manganese to concentrated solution may be either such as to give a magma
which shall be more or less fluid at and above the temperature of the concentrated
boiling solution, or such that the mixture shall be while hot a moist but barely
moist powder just capable of being agglomerated by pressure. In the latter case
it may be formed into small cakes or cylinders or balls or other masses of any
desired shape by such mechanical means as are used for moulding mixtures of
coal-dust with a cementing medium or for moulding other plastic material, and the
resulting cakes, cylinders, balls, or other small masses so formed will not necessarily
require to be desiccated by a special operation before being treated for the decom-
position by heat and air of the chloride of manganese in them, but their desiccation
and the decomposition by heat and air of the chloride of manganese in them may
in some cases be part of one and the same operation. In the former case it will be
necessary to submit the magma to an operation of desiccation before proceeding to
the operation by which the chloride of manganese in it is to be decomposed. The
desiccation of this magma can be performed in brick furnaces or on brick drying-
floors heated from below or otherwise as will be most convenient, or if drying-
floors be used they may be constructed of thick cast-iron plates if precaution be
taken against risk of these plates becoming too highly heated. The magma should
be spread as a thin layer on the beds of these furnaces or on the drying-floors, as the
case may be, a thin layer of powder of manganite of manganese having preferably
first been spread upon these beds or floors. When the desiccation has proceeded
far enough what was magma will now be a thin solid cake capable by reason of the
intervening layer of powder of manganite of being easily detached from the bed or
floor and withdrawn in fragments. These should then be broken if necessary, as
will usually be the case, into smaller fragments suitable to be charged into the
apparatus in which the next or fourth operation is to be performed.
The manner of performing the fourth operation, being that of heating in a current
of air the cakes, cylinders, balls, or other small masses or fragments of a mixture
of manganite of manganese with chloride of manganese, may be that of placing the
said small masses or fragments in apparatus to which heat is applied externally,
and into which is admitted either cold air or air which although it has been heated
has not been heated so highly that it can supply to the contents of the apparatus
all the heat necessary to the accomplishment of the desired reaction. I prefer

page_text: however to perform this fourth operation in apparatus to which heat need not
necessarily be applied externally by forcing into and through the apparatus charged
with the small masses of the said mixture air which has previously been so highly
heated by means of a Cowper-Siemens stove or otherwise, that it can of itself raise
the temperature of the contents of the apparatus to the point at which its oxygen
can react upon the chloride of manganese in them. This fourth operation may be
either intermittent or continuous, but I prefer that it should be continuous, and I
prefer to perform it in an apparatus consisting of a series of distinct compartments
so arranged and disposed that one or more of the said compartments shall be
capable of being isolated at will to permit of their being discharged and re-charged
while the other compartments are at work, and so that the gases or. mixture of
gases and vapours passing from one part of the apparatus at a high temperature
shall be caused to give up much of their heat to those portions of the charge
contained in other portions of the apparatus which have not yet reached that
temperature.
.
One form of apparatus by which this method of proceeding may be carried into
effect consists of a series of vertical iron cylinders lined internally with brick.
The number of such cylinders which it may be best to employ will vary with
circumstances, but for the purpose of the present description I will suppose it to be
eight, and I will indicate the eight cylinders by the letters A, B, C, D, E, F, G,
and H. I will suppose the eight cylinders to be arranged in two rows of four
each, A, B, C, and D in one row, and E, F, G, and H in another row, the two rows
of four cylinders each being so placed that A and H, B and G, C and F, and D
and E, are respectively opposite to each other. Between the two rows of cylinders
is a conduit for conveying to them highly heated air. Each cylinder is divided
vertically into two compartments by a diaphragm or partition of brick-work, which
either does not descend quite to the bottom of the cylinder, or, if it does descend
otherwise to the bottom of the cylinder, has in it at the bottom either an aperture
or several apertures for the passage of the gaseous current. In the top of each
cylinder are two apertures, one over each of the two compartments into which the
cylinder is divided by the vertical partition in it. Through these apertures the
cylinders are charged with the small masses of mixture of manganite of manganese
and chloride of manganese from which chlorine is to be evolved, and by means of
elbow-pipes, the extremities of which can make gas-tight joints with flanges or
other convenient appliances surrounding those apertures, communication can be
established at will between each cylinder and the conduit before mentioned,
between each cylinder and the cylinder next in the series, and between each
cylinder and a second conduit. It will be convenient to speak hereinafter of the
first mentioned conduit as "the air-main," and of the other conduit as the
"chlorine-main." In each of the two conduits are apertures by means of which
and elbow-pipes either cylinder can be connected at will with, or disconnected at
will from, either conduit.
I will now suppose that the seven cylinders A to G inclusive are all charged with
small lumps of the mixture of manganite of manganese with chloride of manganese,
and that an elbow-pipe connects the air-main with the left of the two apertures in
the top of the cylinder A, and that elbow-pipes similarly connect the other aperture
in the top of A with the left aperture in the top of B, the right aperture in the top
of B with the left aperture in the top of C, the right aperture in the top of C with
the left aperture in the top of D, D similarly with E, E similarly with F,
F similarly with G, and the further aperture in the top of G with the chlorine-main.
All the apertures in the air-main except that in communication with A, and all the
apertures in the chlorine-main except that communicating with G, being closed, and
highly heated air from a hot-blast stove being forced into the air-main, highly
heated air will enter A by one of the apertures at the top of that cylinder, will
pass down one side of the partition dividing that cylinder, and will then pass
under that partition, and then up on the other side of it. A mixture of nitrogen,
air, free chlorine, and vapour of hydrochloric acid will now pass from the top of A.

page_text: by the other aperture in the top of that cylinder into the elbow-pipe by which A
communicates with B, the gaseous current then successively traversing B, C, D, E,
F, and G, just as it had traversed A, and finally passing from G into the
chlorine-main, which it will reach at a comparatively low temperature. While
the current is thus passing into A, thence into and through B, C, D, E, F, and G
successively, and from G into the chlorine-main, workmen will have been
charging the cylinder H. When the charge contained in the cylinder A has
been sufficiently treated, the entrance of hot air into the air-main will be stopped
for a moment, A will be disconnected from the air-main and from B; the air-main
will be connected with B instead of with A; G will be disconnected from the
chlorine-main and connected with H, H being now connected with the chlorine-
main, and then air from the hot-blast stove will be re-admitted into the air-main.
The gaseous current will now enter B, will traverse successively B, C, D, E, F, G,
and H, and will pass from H into the chlorine-main. While this is going on, A will
be discharged and re-charged. When the charge in B has been sufficiently treated,
and A has been discharged and re-charged, B will be isolated for discharging and
recharging, C now becoming the cylinder which the hot air enters, and Å the
cylinder from which the gaseous current passes into the chlorine-main, after having
traversed successively C, D, E, F, G, H, and A. From these examples the other
successive changes in the course of the gaseous current will be understood.
For the purpose of discharging the cylinders they are provided with doors in
their lower part.
Instead of the series of cylinders being arranged in two straight rows as above
described they may be arranged in a circle or otherwise as may be more convenient
in each case. Instead of their being charged by the apertures by which the gaseous
current enters and leaves them they may be charged by special apertures, and the
apertures by which the gaseous current enters and leaves them may be in the upper
part of their sides instead of in the positions above indicated. Instead of the
connections of cylinder with cylinder and of the cylinders with the air-main and
the chlorine-main being made by means of movable elbow-pipes, as above described,
they may be made by means of fixed pipes having valves or dampers in them. The
cylinders may moreover be without internal partitions, the gaseous current in such
case passing either down one cylinder and up the next or passing from the bottom
of one cylinder to the upper part of the next by a pipe or conduit placed externally
to the cylinders themselves.
Another form of apparatus on the same principle consists of a series of horizontal
furnaces, arranged and disposed and connected together by movable or fixed
passages for the gaseous current, in the same manner as I have described, for a
series of vertical cylinders. Such horizontal furnaces however can best be charged
through the doors by which they are discharged. In each such furnace I prefer
that there should be several vertical partitions so disposed as to cause the gaseous
current to pass under one partition and then over the next partition and so on
alternately. Such horizontal furnaces may be so disposed as to admit of the charges
treated in them being heated otherwise than simply by means of heat previously
communicated to the air by which the charges are treated, that is to say, they may
be furnaces, in the ordinary sense, having fire-places or combustion chambers in
which fuel can be burnt for the direct heating of their charges. When they are
such I prefer that they should be adapted for the burning of producer gas, and that.
the dispositions should be such that any one or more of the series of furnaces may
be being heated externally while the other members of the series are not being so
heated, and moreover such that the fuel gases may be turned off from any one
member of the series and on to the next at will.
The horizontal furnaces last described will be best suited for the treatment of the
mixture of manganite of manganese with chloride of manganese when a large
proportion of manganite is employed in making such mixture, and it is aggregated
by pressure and moulded into small masses of such shape as may be desired by
mechanical means. Such masses may be charged into that one of the series of

page_text: horizontal furnaces which for the time being is coolest without being previously
subjected to desiccation, and their desiccation be effected by the hot mixture of
chlorine and other gases which will subsequently pass into that furnace from the
furnaces which during the operation then in progress will be earlier members of the
series, the desiccation of the small masses of mixture and the subsequent decompo-
sition of the chloride of manganese in them thus being parts of one and the same
operation. The vertical cylinders above described will be better adapted for the
treatment of mixtures containing smaller proportions of manganite of manganese,
and which have been desiccated previously to their treatment for the decomposition
of the chloride of manganese contained in them. When the charge is treated by
hot air without heat being applied to it otherwise the temperature to which the air
has been previously raised should preferably be such that the heated air shall be
capable of raising to or nearly to dull redness the portions of the charge with which
it first comes into contact.
The gaseous current passing off from the apparatus in which the mixture of
manganite of manganese with chloride of manganese is treated by air will contain
not only free chlorine but also inert gases, vapour of hydrochloric acid, and vapour
of water. It must first be passed into apparatus in which these vapours will be
condensed out from it, as will be well understood, and then into apparatus in which
its chlorine shall be absorbed.
The method and apparatus for the treatment by heat and air of mixtures of
manganite of manganese with chloride of manganese which I have just described
constitute no part of the present Invention but are part of the subject matter of
another Invention for which the Letters Patent numbered 968 of the current year
have been granted to me. What I regard as constituting the present Invention is
the process for manufacturing chlorine which is above set forth, and especially those
parts of it which are above described as its third and fourth operations.
In witness whereof, I, the said Walter Weldon, have hereto set my hand
and seal, this Twentieth day of August, in the year of our Lord One thousand
eight hundred and eighty-one.
WALTER WELDON. (LS.)