MENTS IN THE MANUFACTURE OF CHLORINE
Year: 1881

page_text: 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.
MENTS IN THE MANUFACTURE OF CHLORINE."
" IMPROVE-
The method of manufacturing chlorine which constitutes the present Invention
consists in the following series of operations
First. A portion of the residual solid product of the fourth operation, to be
described below, is dissolved in hydrochloric acid. Chlorine is evolved, and there
is at the same time produced a mixed solution of chloride of manganese and
chloride of magnesium.
Second. The mixed solution produced in the first operation is evaporated to or
nearly to the point at which, if the evaporation were further continued, the mixed
solution would begin to give off hydrochloric acid.
Third. The concentrated solution obtained as just said is mixed with a portion of
the solid residual product of the fourth 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 and
among the interstices between them.
b
Fourth. The cakes, balls, or briquettes formed as just stated are heated in contact
with a current of air. Chlorine is thereby driven off from them, chiefly in the free
state, but partially as hydrochloric acid, and the residual solid product consists of a
compound of binoxide of manganese and magnesia, or of binoxide of manganese
partly with magnesia and partly with manganese protoxide. A part of this
residual product is then used for a repetition of the first operation, and the other
part for a repetition of the third operation.
This method of manufacturing chlorine yields that body in two states. The
chlorine obtained in the first operation is unmixed with other gases, but that

page_text: obtained in the fourth operation is mixed with nitrogen and excess of air, and has
associated with it also some vapour of hydrochloric acid. The gaseous current
obtained by the fourth operation must thus be passed through an apparatus in
which its hydrochloric acid shall be condensed out from it before it is treated for
the absorption of its chlorine from it, as will be well understood. The said
apparatus may be any of those which are ordinarily employed for the condensation
of hydrochloric acid.
It will in some cases be desirable that the cakes or briquettes formed in the
third operation be dried before being treated by air in the fourth operation.
During such drying they will evolve hydrochloric acid, which also must be passed
into condensing apparatus, as will be well understood.
The fourth operation may be conducted by applying heat directly to the exterior
of the apparatus in which that 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 by air
previously so highly heated as to be capable of raising the charge to the temperature
at which the required reaction can take place..
The fourth 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 24th August
1881.
"
WALTER WELDON, of Rede Hall, Burstow, in the County of Surrey. IMPROVE-
MENTS IN THE MANUFACTURE OF CHLORINE."
This Invention relates to the manufacture of chlorine by a method consisting in
the four following 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 consists
essentially of peroxide of manganese combined or associated cither with magnesia
only, or partly with magnesia and partly with manganese protoxide. This solid
residue of the fourth operation will hereinafter be called manganite of magnesium.
The reaction of aqueous bydrochloric acid upon this body gives rise to an evolution
of chlorine gas, and there is at the same time produced a residual mixed solution of
chloride of manganese and chloride of magnesium.
Second. The aforesaid residual solution is evaporated to or nearly to the point at
which, if its evaporation were further continued, the concentrated solution would
begin to give off vapour of hydrochloric acid.
Third. The solution which has been concentrated as just said is mixed with
manganite of magnesium, and the mixture is formed into cakes, cylinders, balls, or
other small masses, such that when charged into a suitable apparatus, air, and other
gas or gases shall be able to 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 chlorides contained in them, and transforms these
chlorides into manganite of magnesium, at the same time driving off their chlorine,
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 magnesinm with chloride of manganese and chloride of magnesium,
at the end of it thus consist wholly of manganite of magnesium, 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.
It is these third and fourth operations which constitute what is new in the
present Invention. The first and second operations, above described, are the same
as those of a method of manufacturing chlorine for which the Letters Patent,
numbered 317 of the year 1872, were granted to me. It was not possible to
perform economically that method of manufacturing chlorine, among other reasons,
because that method required that the concentrated solution produced in the
second operation should be delivered as a liquid into the furnaces in which it was
to be desiccated. Those furnaces were rapidly destroyed by a comparatively cool
liquid being charged into them each time they were at their hottest. By mixing
this concentrated solution before proceeding to its further treatment with
manganite of mangnesium from a previous operation or from previous operations,
completely avoid what was before a fatal difficulty. At the same time I am
enabled to effect the subsequent treatment of the chlorides of manganese and
magnesium by heat and air much more conveniently and economically than here-
tofore, and to obtain much more of their chlorine in the free state, and much less
of it merely as vapour of hydrochloric acid.
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

page_text: Invention. Methods of performing it are described in the Specification filed in
pursuance of the Letters Patent aforesaid. It must be so performed, however, that
the acid shall be completely neutralized by the manganite of magnesium. To this
end, towards the latter part of the operation, an excess of manganite of magnesium
must be used. Those portions of the acid which would not dissolve peroxide of
manganese will then be neutralized by the protoxides contained in such 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 magnesium is added thereto. The earlier part, of this first
operation must necessarily be performed 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 peroxide of manganese, and in so capable of yielding
more chlorine on more manganite of magnesium being added to it, the
neutralization of this last part of the acid by means of the protoxides contained in
an excess of manganite of magnesium 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 still liquors of the present
Weldon process, and the mode of proceeding will be the same as that followed in
the operation just referred to, except that manganite of magnesium will be used as
the neutralizing agent instead of the carbonate of lime.
The second operation above described may equally be performed in many ways,
and in its case also no particular method 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 attack materially if care have been previously taken that
it be perfectly neutral. The evaporation should preferably not be carried to the
point at which the boiling concentrated solution would give off hydrochloric acid,
but it should be carried nearly to that point.
As regards the third and fourth operations which are above described, and which
. constitute what I believe to be new in the present Invention, I do not confine
myself to any particular method of performing them, since they may be performed
in very 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 magnesium and 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 magnesium
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 to keep its contents at or about the temperature of
the boiling concentrated solution. The proportion of concentrated solution to
manganite of magnesium may be either such as to give a magma which shall be
more or less fluid at and above the temperature of the boiling concentrated 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 the mixture 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, as will be well under-
stood, and the resulting cakes, cylinders, balls, or other small masses will not
necessarily require to be desiccated by a special operation before being treated for

page_text: the decomposition by heat and air of the chlorides contained in them, but their
desiccation and the decomposition by heat and air of the chlorides in them may
in some cases be part of one and the same operation. In the former case it will be
necessary that the mixture should undergo an operation of desiccation previously
to the operation by which the chlorides in it are to be decomposed. This operation
of desiccation may be performed in brick furnaces, which must be close or muffle
furnaces, connected with condensing apparatus, because not only steam by also
some vapour of hydrochloric acid will come off during the desiccation. The magma
should be spread as a thin layer on the beds of these furnaces, on which a thin
layer of dry powder of manganite of magnesium should first have been spread.
When the desiccation has proceeded sufficiently far what was magma will now be
a thin solid cake, which by reason of the layer of powder under it can be easily
detached from the bed of, the furnace 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 mixture of
manganite of magnesium with chloride of manganese and chloride of magnesium,
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, however, to perform that operation in apparatus to
which beat need not necessarily be applied externally by forcing into the apparatus
charged with small masses of the said mixture air which has been previously so
highly heated by means of a Cowper-Siemens stove or otherwise, that it can of
itself raise the temperature of the small masses of mixture to the point at which
the oxygen of the heated air can react upon the chlorides contained in them. This
fourth operation may be either intermittent or continuous, but I prefer that it
should be practically continuous, and I prefer to perform it in an apparatus cón-
sisting 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 attained 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 interiorly with brick. The
number of such cylinders which it may be best to employ will vary with circum-
stances; 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 magnesium with chloride of magnesium and chloride of manganese, from which
chlorine is to be evolved; and by means of elbow-pipes, the extremities of which

page_text: 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 these 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 magnesium with chloride of
magnesium and 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 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 re-charging, C now becoming the cylinder which. the
hot air enters, and A 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 con-
venient in each case. Instead of their being charged by the apertures by which
the gaseous current enters and leaves then 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 connection 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,

page_text: 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 hot air or gases or vapours 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 may 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 magnesium with chloride of magnesium and chloride
of manganese when a large proportion of manganite is used 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 can be charged into
that one of the series of horizontal furnaces which for the time being is coolest,
without being previously subjected to desiccation, and their desiccation will 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, and the desiccation of the small
masses of mixture and the subsequent decomposition of the chlorides in them will
thus be 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 magnesium, and which have been desiccated previously
to their treatment for the decomposition of the chlorides 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 magnesium with chloride of magnesium and 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 magnesium with chloride of magnesium and chloride of manganese
which I have just described constitute no part of the present Invention, but are a
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,--
Firstly. Mixing with manganite of magnesium the residual solution resulting
from the manufacture of chlorine by the treatment by aqueous hydrochloric acid of
another portion of manganite of magnesium, after the said solution has been
suitably concentrated by evaporation, and forming the said mixture into small
masses or lumps, such that when they are charged into a suitable apparatus air sent

page_text: into that apparatus may be capable of passing into and through and among the
interstices between them, and
Secondly. Obtaining free chlorine from the chlorides of the said residual solution
by heating the small masses of a mixture of those chlorides with manganite of
magnesium, formed substantially as just said in presence of a current of air.
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. (L.S.)