Improvements relating to the Production of Chlorine.
Year: 1888

page_text: COMPLETE SPECIFICATION.
Improvements relating to the Production of Chlorine.
I, JOHN AUGUST JUST, of Syracuse, in the County of Onondaga, and State of New
York, United States of America, Chemist, do hereby declare the nature of this inven-
tion 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 an improvement in Processes for producing Chlorine; and
it consists in the novel combination of materials and the practical utilization of
chemical reactions, taking place at certain temperatures, substantially as will be
hereinafter more fully described and claimed.
In order to enable others skilled in the art to which my invention relates, to avail
themselves of its benefits, I will now proceed to describe its use and operation,
referring to the accompanying drawings, which I have prepared to enable me to more
clearly and fully describe my process, and to enable others to more easily understand
its working, and in which:
Figure 1 is a diagram view of such a plant as I prefer to use in carrying out my
process.
Figure 2 is a detail section of the devices for recovering the manganese dioxide and
Nitric Acid.
Figure 3 is a detail section of one of the stills, showing its connections to the pipe
systems, and manner of operating the syphon.
Figure 4 is a sectional view of the washer.
Figure 5 is a plan view of the syphon trap, and
Figure 6 a cross section of the evaporating pan.
use a still or series
For the better carrying out of my invention on a large scale,
of stills, connected in one or more rows termed batteries, which are varied in number
and size according to the capacity of the desired plant. I place the series of stills
constituting a battery in a trough-a,-preferably of wood, lined with sheet lead of

page_text: requisite strength, as at-a-and in the bottom of the trough I place a coil of steam
pipes a, for heating the stills, as will be more fully explained hereinafter.
Each still composing a battery is an earthen-ware jar, resembling those often
used in chemical processes and apparatus, and is provided with a removable cap or
cover the rim of which fits into a groove in the top of the jar, as at-2,-and
this groove is provided with a water seal into which the rim of the cap enters, and
this opening is thus effectually sealed against the admission of air, or the escape of
gas from the still.
Upon one side, the still is formed with a vertical passage-c-in its side, opening
inwardly at its lower end, and outwardly at its upper end, and to this latter opening
is secured a rubber tube-c¹,-provided with a glass tube-², which is extended
down and connects with a trap-³-connected to a drain pipe system, as will be
presently explained, and this device acts as a syphon to clear the still after the operation
is completed upon a charge.
Within the still is placed a perforated vessel-e,-to receive the charge, and at the
top of the still is an opening-e-also provided with a cap and a liquid seal, at which
point the acid used is entered from a system of distributing pipes. Also at the top
of the still is formed a nozzle-el-connected by a pipe--with a system of
pipes for carrying off the gas formed in the still; and each still of the battery is
separate and independent, and independently connected to the pipe and drain systems
mentioned, so that each still may as desirable, be operated independently of the
others.
The different pipe lines referred to, are run as follows:
A receptacle-g-of proper size and material, divided into two compartments, to
receive the two acids, is provided with a pair of faucets-g'.-These faucets discharge
into a single main acid pipe--extended in the proper direction, and this main
pipe is provided with one, two, or more branches--which are extended along
beside and above the series of stills forming the batteries, and are provided with
outlets and cocks-y-by which the acids are supplied to the stills through the
liquid scaled opening prepared for that purpose in the stills, as already described:
and it will be noted that by a proper arrangement of stop-cocks &c., the acids are
supplied to any or all of the stills at pleasure, and in accordance with the manner to
be charged.
The pipe line with which the still syphons connect, may if desired, be laid in
the ground, and its branches and main line lead directly to a cistern or well, of proper
material, into which all the residue liquor of the stills is conducted, after the charge
has been worked.
The main and branch gas main-h,-into which the chlorine gas generated in the
stills is discharged, leads directly to a suitable washer-i,-where it is deprived of
all moisture it may contain, and from thence is extended to the chloride of lime
chambers-i¹.
ད
For the recovery of the acid and manganese used, I provide a furnace or oven-k-
having a large pan contained therein, (not necessary to show in this connection), into
which the residue liquor from the well is placed, and heat applied. The gas liberated
by this operation escapes by a pipe--and the manganese dioxide is left in the pan
in a perfectly pure form, dry, and ready for use again at any time. The pipe-
conducts the nitrous vapors arising from the reaction in the furnace, to a tower-3-
shown in detail in figure 2, through which they rise in a zig-zag course to the top
a pipe admitting atmospheric air, to mingle with the vapors, and at the top of
the tower a spray of water is admitted, which runs down and serves to condense the
vapors as they pass over, the zig-zag shelves of the tower. This water and condensed
vapors are carried off directly to the last jar of the series of condensors, and circulate
back toward the first one, in the opposite direction to the course pursued by the vapors
still uncondensed. From this the uncondensed vapors are conducted through a cooler
or condensor--to the first one of a double row of jars-m,-through which they
pass from jar to jar till arriving at the last, from which they are led by a pipe-0,-
to a second tower-o'-where they are effectually condensed, and through a small

page_text: pipe again to the last jar of the series. It will thus be seen that all the manganese
dioxide, and all or nearly all of the nitric acid used in the process, is recovered, and
re-used indefinitely by the arrangement of plant herein shown.
It will now be understood that I do not in this application confine myself to this or
any other particular plant or apparatus, and have only given a general description of
such a plant as is readily used, in order that the process proper, which I shall now
proceed to describe, may be the more readily and easily understood. It is in fact
merely by way of illustration, and I have not entered into a description of its details,
nor do I make any claim for it herein, as I intend to make it the subject of a separate
application for a patent, as the preferred form of apparatus, used in carrying out my
process, for the manufacture of chlorine.
1 fill the lead lined troughs in which the generators or stills forming a battery, are
placed to a proper depth with a strong solution of calcium chloride, serving as a bath,
which is heated by means of the steam pipes, to the necessary degree of heat to drive
off from the stills, all the chlorine contained in the hydro-chloric acid, in the mixture
forming the charge. Calcium chloride solution is here employed as a bath, because
the required degree of heat cannot be obtained by a water bath, as the temperature
necessary is about 245° F.
The ingredients used in my improved process are, Nitric Acid, Hydro-chloric Acid,
and manganese dioxide, and I find by experiment the best proportions of these ingre-
dients for producing a perfect operation and result, are as follows:
3.3 equivalent of Nitric Acid, (NHO 3) and 3.2 equivalent of Hydro-chloric
Acid (HC), or 415.8 pounds of Nitric Acid at 1315 specific gravity. and 331.8
pounds of Hydro-chloric Acid at 1180 specific gravity, and 141.9 pounds of Manganese
dioxide (Mn O). Weaker Acids will accomplish the same result but not as completely
and economically, since the residue liquor after the operation is finished, is much
more diluted than if stronger acid had been employed.
The stills are now charged, with chemicals in proper proportions, the Nitric acid
being first run into the stills, then the Hydro-chloric acid. When the battery of stills
is thus charged with the required amount of acids, the Manganese dioxide for each
still, having been previously prepared, weighed and placed conveniently at hand, is
placed in the perforated vessel in each still, preferably by means of a wooden funnel
of sufficient size to reach nearly to the liquid and so prevent splashing. The cover of
the still is then at once replaced in its liquid seal, as the evolution of chlorine
commences at once on the insertion of the Manganese dioxide, and this chlorine gas
passes off at the proper outlet, and into the gas pipe system, as previously explained.
In charging a battery of stills it is always advisable to supply acids beginning at the
first still in order, and from this consecutively through the row, as the acid pipes are
given a slight incline, and this mode of procedure gives a chance to drain out the
pipes after the charging is completed. The temperature supplied by the steam pipes,
and the bath in which the stills are placed, is such as to drive off every particle of
chlorine gas from the mixture, and it passes through the pipe-line to the washer,
where it is deprived of all remaining moisture, and thence passes on to the chloride of
lime chambers.
When the charge in the stills is exhausted the gas connections are shut off by
suitable stop-cocks provided for the purpose, and the syphons started, through which
the residue liquor remaining in the stills, is drawn off into the main--and conducted
to the well or cistern.
In the chloride of lime chambers, upon the lime placed therein, to be converted
into chloride of lime by the action of the chlorine gas, is usually found a bard and
thick superficial crust, which is formed from the beginning by reason of the lime too
greedily absorbing the gas, and this prevents or greatly impedes the further absorp-
tion. It has been customary to open the chamber, and break up this superficial
crust, or turn the lime over, to expose the less chlorinated lime from the bottom, to
the action of the chlorine. in order that the chloride of lime should be brought up to
proper and even strength. This annoyance I overcome and greatly facilitate the
operation, as follows: To the chlorine gas pipe, before it reaches the chloride of

page_text: lime chambers, I supply a quantity of air, say from 20 to 35 per cent., and I find that
this not only facilitates the production of the chloride of lime, but it also prevents
the formation of the crusts above mentioned, and gives me a better result in
consequence.
In the manufacture of chloride of lime, at a stage when the lime in the chambers
is nearly saturated with the chlorine, some pressure accelerates the process very much,
and produces a stronger article. This has heretofore been generally effected by
steaming, but I find I can perform this to much better advantage by the use
of compressed air, which is always readily had in chloride of lime and Acid Works,
and is much more economical as well as more advantageous, than the old steaming
process.
The next step in the process is the recovery of the nitric Acid and Manganese
dioxide, from the residue manganous nitrate liquor, which has been run into the well
or cistern from the worked out stills.
The residue manganous nitrate, is now brought into the furnace, and delivered in
the large pan contained therein. The fire is very gradually brought up, and at first
watery vapors escape and the liquor is thus concentrated, as the heat of the liquid
increases. These watery vapors may be allowed to escape, or are condensed in the
first small tower, in passing over the zig-zag trays therein, the liquid which condenses
there being carried off at the bottom of the tower, by a glass tube, and conveyed to
the last jar of the condensing series, as shown in figure 2. From this last jar, it is
caused to travel from jar to jar, by means of connecting syphons, till it has passed
through the system and reached the first jar of the system, and thus the nitrous
vapors are compelled to travel in the opposite direction to the water and weaker acids,
and in consequence, a complete condensation, and strong acid is obtained on arriving
at the jar nearest the beginning of this condensing system where strong acid is
continually drawn off for use in the generators. Also the water and weaker acid
from the last tower, which retains the remaining traces of nitric acid, which have
escaped condensation, runs off at an outlet provided and also enters the last jar,
and takes the same course as the liquid entering from the first tower, as just
described.
The gases generated by the reduction of nitric acid in the recovery furnace, ascend
through the condensing and cooling tower, where they are regenerated into Nitric
Acid by an ascending current of air, and a descending jet or spray of water, and the
escaping and still uncondensed gases being mixed with air, pass on to the condensing
jars, wherein the weaker acid coming from the last jar circulates towards the first
jar of the condensing system.
Thus the gases travel in an opposite direction to the liquid, and a practically
complete recovery of the nitric acid only depends upon first, a complete decomposition
in the furnace second; the thorough cooling of the nitre gases after leaving the
furnace, and third; the insurance of a slight excess of air throughout the whole
course of condensation.
The decomposition of the manganese nitrate in the furnace, commences at a
temperature of about 280° F, and continues while the temperature is gradually raised
to about 380° F, to the maximum degree of 400° F, when the mass will be found
solid upon the pan bed, consisting of very pure manganese dioxide, which is again
used in freshly charging the stills, and the process is thus continuously operated,
the manganese dioxide, and nitric acid being recovered and re-used indefinitely as
described.
It will thus be seen that this process of making chlorine, consists really of three
stages, viz.; the reaction in the stills; the reaction in the furnace; and the reaction in
the condensation and recovery of the nitric acid. Stated in chemical formula, these
several reactions appear as follows:
Reaction of first stage in stills:

page_text: * NHO,
This formula will concisely show to any one familiar with the art, the successive
steps taken, and the full practical recovery of the manganese dioxide and the nitric
acid. As heretofore stated, I do not desire to confine myself to the proportions of
ingredients named or to the strength set forth, as some changes may be made in
these details, without departing from the spirit of my invention, and produce the
same result, but the strength and proportions named I find by experiment to be the
best for producing at an economical figure the very best results, and prefer them
for this reason.
While in theory and in laboratory experiments, the results of any chemical process
is obtained by the use of the different chemicals in their exact equivalent pro-
portions, yet in the operation of such process commercially on a large scale, there
is danger of failure by an excess of one over its equivalent of another. Thus in
the present instance, should there be in practice, an excess of hydro-chloric acid over
its equivalents of nitric acid and manganese dioxide, all the chlorine contained in
the hydro-chloric acid used in the charge could not be evolved, and the quantity so
left undecomposed remains in the residual manganous nitrate liquor, thereby
contaminating the same, causing a complication of results in the stage of decomposing
said residual liquor. If upon the other hand, we suppose that the manganese
dioxide and hydro-chloric acid to be in excess of the nitric acid, such excess of
hydro-chloric acid will form with its equivalent of manganese dioxide, manganese
chloride (Mn C) which on the boiling down of the residual manganous nitrate
liquor, would contaminate the recovered manganese dioxide and nitric acid.
this acid and the manganese dioxide are used and re-used in the continuous
operation of the plant, this defect would be magnified with each recovery, till it
would soon be necessary to discard the recovered ingredients and commence with a
fresh charge. To obviate all difficulty of this nature, it will be noted that the
figures herein given are not the exact chemical equivalents, but represent an excess
of nitric acid over the hydro-chloric acid, and an equivalent excess of manganese
dioxide. This excess of these ingredients fully insures the evolution of all the
chlorine in the hydro-chloric acid, and leaves in the residue liquor no trace of
chlorine to interfere in any way with the complete and perfect recovery of the
manganese dioxide, and the nitric acid. Special attention is called to this small
excess of these two ingredients, as it is an essential to the perfect working of the
process on a large scale, and without it failure would soon result.
As
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed 1 declare that what I claim is :-
1. The within described process of making chlorine, consisting essentially in
introducing into a generator, nitric acid, hydrochloric acid, and manganese dioxide,
the nitric acid and manganese dioxide being in equivalent excess of the hydro-
chloric acid, and subjecting the generator to heat, whereby all the chlorine of the
hydrochloric acid is evolved, substantially as and for the purpose specified.
2. The process of making chlorine, consisting in charging a generator with nitric
acid, hydrochloric acid and manganese dioxide, subjecting the generator to beat
until all the chlorine in the charge is evolved, then subjecting the residual liquor to
heat to decompose the manganous nitrate, and thus manganese dioxide is formed,

page_text: while the nitrous vapors escape, and are recovered as nitric acid, substantially as set
forth.
3. The process of making chlorine, consisting in charging a generator with nitric
acid, hydrochloric acid, and manganese dioxide, subjecting the generator to heat until
all the chlorine gas is evolved from the charge, then decomposing the residual
manganous nitrate liquor by heat when manganese dioxide and nitrous vapors are
formed, and finally withdrawing the nitrous vapors into condensors where they are
brought into intimate contact with air and water, and thus the nitric acid is
recovered by condensation substantially as and for the purpose set forth.
Dated this 16th day of October 1888.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London,
Agents for the Applicant.