IMPROVEMENTS IN AND RELATING TO THE MANUFACTURE OF CHLORINE
Year: 1883

page_text: LETTERS PATENT to Walter Weldon, of Rede Hall, Burstow, in the County of
Surrey, for an Invention of IMPROVEMENTS IN AND RELATING TO THE
MANUFACTURE OF CHLORINE
PROVISIONAL SPECIFICATION left by the said Walter Weldon at the
Office of the Commissioners of Patents on the 23rd August 1883.
WALTER WELDON, of Rede Hall, Burstow, in the County of Surrey, "IMPROVE-
MENTS IN AND RELATING TO THE MANUFACTURE OF CHLORINE,"
The process of manufacturing chlorine which constitutes the present invention
consists in the following series of operations:
First. Treatment together in chlorine stills of aqueous hydrochloric acid and the
artificial oxide of manganese obtained as will be indicated in what follows. The
residue of this operation will be a solution of manganese chloride, usually containing
more or less free acid.
Second. Evaporation of the solution of manganese chloride which constitutes
the residual product of the first operation, after having removed therefrom any
free acid which may at first be associated therewith, such evaporation, or
evaporation and subsequent heating, being carried far enough to give a solid
manganese chloride, preferably containing not much more than one equivalent of
water.
Third. Heating the solid manganese chloride thus obtained in contact with air,
so as to decompose it into free chlorine and an oxide of manganese capable of
serving again in the first operation.
Before subjecting the solid manganese chloride to the third operation, I prefer to
reduce it by mechanical means to the state of a more or less fine powder. This
powder may be submitted to the third operation either by itself or in admixture
with powder of the oxide of manganese obtained as the residual product of the
third operation. The powder of manganese chloride, or mixture of powder of
manganese chloride with powder of residual manganese oxide from the third
operation, may be either treated, in apparatus not heated externally, by previously
heated air, heated in hot-blast stoves, as will be well understood, or it may be
ГД С11

page_text: treated, either by cold air or by previously heated air, in apparatus heated
externally. A convenient apparatus for the purpose, though I do not confine
myself to such apparatus, will consist of a cylinder or retort somewhat after the
fashion of the retorts used in the manufacture of coal-gas, but so arranged that it
can be made to revolve upon its longer axis, the powder or mixture of powders to
be treated in it being fed into it at one of its extremities and the residual product
of the operation being delivered from it automatically at its other extremity.
When this apparatus is to be heated externally, it should be enclosed in a second
cylinder, combustible gases being burnt in the space between the inner cylinder
and the outer cylinder..
To free from acid the solution of manganese chloride produced in the first
operation, when this cannot be done by digesting that solution with excess of the
residual product of the third operation, I pass that solution down towers, similar
to what are known as Glover towers, up which I cause heated gases to ascend, the
hot gases entering the towers at the bottom and the acid solution entering them at
the top. The solution thus reaches the bottom of the towers divested of its ucid,
which goes off from the top of the towers as vapour, and is conducted from the
top of the towers to suitable condensing apparatus, as will be well understood.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Walter Weldon in the Patent Office on the 22nd February
1884.
WALTER WELDON, of Rede Hall, Burstow, in the County of Surrey, "IMPROVE-
MENTS IN AND RELATING TO THE MANUFACTURE OF CHLORINE,"
The patent numbered 966, and dated the 7th. March, 1881, was granted to me
for a method of manufacturing chlorine consisting in the following successive
operations:
First. Solution in aqueous hydrochloric acid of a portion of the oxide or
mixture of oxides of manganese produced in the third operation: this first
operation yielding free chlorine, unmixed with other gases, and a residual solution
of manganese chloride.
Second. Concentration by evaporation of the said residual solution of manganese
chloride, and the formation of cakes, balls, or briquettes of a mixture of such
concentrated solution of manganese chloride with a portion of the oxide or mixture
of oxides of manganese which is the residual product of the third operation.
Third. Heating the said cakes, balls, or briquettes in a current of air, and
thereby driving off the chlorine of their manganese chloride in the free state, and
converting the manganese of that chloride into an oxide or. mixture of oxides
capable of being used again in the first operation.
By my present invention, the process thus described is modified as follows:-
Instead of simply concentrating by evaporation the solution of manganese
chloride which is the residual product of the first operation, and then mixing such
concentrated solution with a portion of the oxide or mixture of oxides which is
the residual product of the third operation, by my present invention the evapora
tion of the said solution of manganese chloride is carried to dryness, and the
resulting solid manganese chloride is then treated by heat and air in the state of
powder, its treatment by heat and air being performed either in apparatus of the
nature of a muffle furnace, or of a series of muffle furnaces connected together, or
in an apparatus of the new kind which will be described below, or in an apparatus
not heated externally but in which the said powder of manganese chloride is
brought into contact with air which has previously been raised to a high
temperature, the powder of manganese chloride being in either case charged into
the apparatus in which it is to be treated by heat and air either by itself or in
admixture with powder of the oxide or mixture of oxides which is the solid
residual product of the third operation.
As modified by the present invention, therefore, the said process of manufacturing
chlorine consists essentially in the following series of operations:-
First. Solution in aqueous hydrochloric acid of the oxide or mixture of oxides
of manganese produced in the third operation.
Second. Evaporation to dryness of the resulting solution of manganese chloride.
Third. Treatment of the resulting solid manganese chloride by heat and air, the
said solid manganese chloride being in the state of powder, and being charged into
the apparatus in which it is to be so treated by heat and air either alone or in
admixture with a portion of the oxide or oxides of manganese produced in a
preceding third operation, such oxide or oxides of manganese being also in the
state of powder.
The method of performing the said first operation will be well understood by
manufacturers of chlorine. I need only observe respecting it that the solution of
manganese chloride which is its residual product should preferably, although this
is not absolutely essential, be completely neutral before it is submitted to

page_text: evaporation. One method of neutralizing it may consist in adding to the acid
solution which remains after the hydrochloric acid employed has dissolved as much
oxide or oxides of manganese as it is capable of dissolving completely a further
quantity of such oxide or oxides, so as to saturate the free acid of that solution by
the manganese protoxide contained in such further quantity of oxide or oxides,
leaving the dioxide contained therein undissolved. When this method is followed,
the neutralized solution of manganese chloride will at first hold in suspension
manganese dioxide, and perhaps other oxide or oxides of manganese. In such case,
such dioxide, or mixture of dioxide and other oxide or oxides, should be separated
from the said neutralized solution, before it is submitted to evaporation, such
separation being performed either by subsidence and decantation, or by filtration,
as may be preferred, and the separated dioxide, or mixture of dioxide and other
oxide or oxides, being used in the next first operation, preferably at the com-
mencement thereof. The present invention includes, however, an alternative
method of depriving of its free acid the said acid residual solution. This method
consists in evaporating off that acid in towers, similar to Glover towers, packed
with any convenient material which is not unduly attacked by either hydrochloric
acid or manganese chloride, and up which hot gases, entering at the bottom, ascend,
while the acid solution is fod in at the top, and so in its passage down the towers
comes into intimate contact with the ascending current of hot gases, which are so
enabled to carry off from it its hydrochloric acid and some of its water. The
mixture of gases and vapours passing off from the top of these towers may be
coolod and its hydrochloric acid condensed out in the usual way, as will be well under-
stood. When the third operation is performed upon powder of manganeso chloride
mixed with powder of manganese oxide or oxides, the solid residual product of the
third operation must be divided always into two portions: one to go to the "stills'
in which the first operation is performed, the other to be mixed with powder of
manganese chloride in a succeeding third operation.
The second of the three operations last above described may be performed in any
one of many ways, and in any one of many kinds of apparatus, as will be well
understood by practical men, and no particular method of performing it constitutes
any part of the present invention. I now prefer to perform it, however, by the
method described in the specification of a patent applied for on the 27th.
December, 1883, and numbered 5868, by which method the second operation yields
directly solid manganese chloride in small crystals. When, however, the second
operation is performed in such wise as to yield the solid manganese chloride in
masses, as when the solution of manganese chloride is evaporated by "over heat
in brick-lined pans, it must be reduced to powder by mechanical means bofore
being submitted to the third operation.
"
The third operation may be perforined in apparatus of the nature of a muffle
furnace, or of a series of muffle furnaces communicating one with another. An
apparatus of the latter kind is described in the specification of my patent No 968 of
the year 1881. Or the said third operation may be performed in the new
apparatus, the general construction of which is shown in the accompanying
drawing. In Figure 1 of that drawing e, e, e, e is a retort, somewhat similar to a
gas-retort. This retort may be made of fire-clay. It is enclosed within, and
firmly fixed to, the iron cylinder c, c, c, c, c. This iron cylinder is lined with brick
or fireclay, is closed at both ends, is supported by the rollers d, d, and is so
disposed that it can turn on its longer axis, the retort o, e, e, e turning with it.
Between the outer surface of the rotort e, e, e, e and the inner surface of the brick-
lined iron cylinder c, c, c, c, c, is an annular combustion chamber, w, 0, 2, 20.
Gaseous fuel, admitted into this annular combustion chamber by the pipes f, f
conveyed to the apparatus by the pipes j, j, j, is admitted into this annular com-
bustion chamber by the pipes f, f. The pipes f, f; move with the revolving
cylinder c, c, c, c, c, but the pipes j, j, j, are fixed. The pipes f. f, communicate
with the pipes i, j, j, as shown in the drawing, or by any other equivalent means.
The air required to burn the gaseous fuel thus conveyed into the annular

page_text: combustion chamber may be admitted thereinto, as shewn in the drawing, by the
same apertures in one end of the cylinder c, c, c, c as those by which the pipes f,f
enter it. By the apertures h, h, the products of combustion formed in the annular
combustion chamber pass off therefrom into the smoke-box, i, i. This smoke-box
is fixed, and communicates with a chimney. When needful for the obtainment of
sufficient draught, an aspirator must be placed in the flue or channel by which the
smoke-box communicates with the chimney. The material to be treated in the
retort e, e, e, e, is charged into the hopper m, and is thence admitted gradually,
by mechanical means which will be understood from the drawing, or by any
equivalent means, into the pipe n, n, from which it passes into the retort through
one of the two hollow axles of the revolving cylinder c, c, c, c, c.
Its passage
through the said hollow axle may be facilitated by helicoidal paddles placed
within that hollow axle, and fixed to the little axle o, or by other mechanical
means to the same end. The solid product of the reaction taking place
within the retort passes out of it through the other hollow axle of the apparatus
into the tube k, by which it is discharged into any suitable receptacle. In this
other hollow axle there is also indicated in the drawing helicoidal paddles, fixed to
the small axle l. The axles, and o, may either be fixed, or be made to turn in the
opposite direction to that in which the revolving cylinder and the retort enclosed
within it turn. Air enters the retort by the pipe k and the hollow axle with which
that pipe communicates, and the mixture of chlorine and other gases which is the
gaseous product of the action of the oxygen of the air entering the retort upon the
manganese chloride with which it comes into contact therein passes off through the
other hollow axle of the apparatus into the pipe n, n, from which it is conducted
away to apparatus in which its chlorine is to be utilized, having first been passed,
if need be, through cooling and condensing apparatus, as will be well understood,
in order to condense out of it any vapour of hydrochloric acid which may at first
be contained in it. A draught through the retort, and also through the apparatus
in which the gaseous mixture passing off from it is to be treated, must be maintained
by means of an aspirator or aspirators, when sufficient chimney draught is not
available. The apparatus is shown in the drawing in a horizontal position, but it
should preferably be inclined: that extremity of it near which is placed the
hopper m and the pipes n, n, being at a somewhat higher elevation than its other
extremity. Figure 2 of the accompanying drawings represents a section of the
apparatus through the line A, B, of Figure 1. The letters in Figure 2 have the
same signification as the corresponding letters in Figure 1.-The minor details of
the apparatus as above described may be varied in many ways without modifying
the essential features of the apparatus, which consists essentially of a revolving.
cylindrical furnace, enclosing a cylindrical retort, between which and the outer
cylinder is an annular combustion chamber, in which gaseous fuel is burnt for the
purpose of heating the contents of the retort, the apparatus being so disposed that
manganese chloride, or a mixture of manganese chloride and manganese oxide or
oxides, in the state of powder, may be fed into the retort mechanically at one of its
extremities, and oxide or oxides of manganese be mechanically discharged from its
other extremity, air entering the retort at that one of its extremities at which
oxide or a mixture of oxides of manganese is so discharged from it, and chlorine
mixed with other gases passing off from the retort at that one of its extremities
by which the said manganese chloride or mixture of manganese chloride with
manganese oxide or oxides enters it.
When performing the third operation of the process to which this invention
relates in the revolving retort-furnace just described, it will not be so necessary to
mix the manganese chloride with manganese oxide or oxides before charging it
into the apparatus in which it is to be heated in a current of air as when
performing the third operation in apparatus of the nature of a muffle furnace, or
of a series of muffle furnaces connected together. The object of mixing the
manganese chloride with manganese oxide or oxides is simply to divide the
manganese chloride and so to prevent it from agglomerating, when it is heated to

page_text: its point of fusion, into large masses, penetrable by air only slowly and with
difficulty. The revolving retort-furnace, however, will always be cooler at the end
at which its charge is fed into it than at its other end, and its temperature may be
BO regulated that if powder of manganese chloride alone be fed into the retort that
powder of manganeso chloride shall not reach its fusing point until after it has
travelled some distance down the retort and become mixed therein with oxide or
oxides of manganese resulting from the decomposition of manganese chloride
previously fed into it. In such case, the mixture of the manganese chloride with
manganese oxide or oxides which it is practically essential should take placo
before the manganese chloride reaches its fusing point, will be effected in the
revolving retort-furnace itself. When, however, the revolving retort-furnace is
maintained at such temperature that if powder of manganese chloride alone were
fed into it the said manganese chloride would fuse, more or less completely, and so
agglomerate into masses, before it could get mixed with the solid product of the
decomposition of previous portions of manganese chloride, the powder of manganese
chloride must be mixed with powder of manganese oxide or oxides before being
admitted into the retort-furnace. In all cases it will be desirable, in starting a
retort-furnace, to use at first, and for some little time, a mixture of manganese
chloride with manganese oxide or oxides. When the third operation is performed
in apparatus of the nature of a muffle furnace or of a series of muflle furnaces,
it is essential that the powder of manganese chloride should be fed thereinto
previously mixed with powder of manganese oxide or oxides, unless the mode of
proceedure be such that the charge in such apparatus be not heated to the point of
fusion of manganese chloride until it has first undergone partial decomposition at
a lower temperature, the temperature of the charge being raised slowly and only
in proportion as decomposition proceeds, which mode of procedure, however, would
usually be undesirably slow.
What I claim as novel in the invention above described is:
Firstly, obtaining chlorine, mixed with other gases, by heating in a current of
air manganese chloride in the state of powder;
Secondly, obtaining chlorine not mixed with other gases, by dissolving in
aqueous hydrochloric acid the oxide or imixture of oxides of manganese which is
obtained as the residual product of the treatment by heat and air of manganese
chloride subjected to such treatment in the state of powder;
Thirdly, mixing powder of manganese chloride, before subjecting it to the said
treatment by heat and air, with powder of manganese oxide or of a mixture of
manganese oxides previously obtained by treatment of manganese chloride by heat
and air; and,
Fourthly, the use for the treatment by heat and air of powder of manganese
chloride, previously mixed or not with powder of manganese oxide, or of a mixturo
of manganese oxides, of a revolving retort-furnace substantially such as. is above
described.
In witness whereof I, the said Walter Weldon, have hereto set my hand and
seal this eighteenth day of February, in the year of Our Lord One thousand eight
hundred and eighty-four.