Improvements in the Production of Chlorine and of Strong Hydrochloric Acid.
Year: 1890

page_text: Date of Application, 30th Dec., 1890
Complete Specification Left, 30th Sept., 1891-Accepted, 7th Nov., 1891
PROVISIONAL SPECIFICATION.
Improvements in the Production of Chlorine and of Strong
Hydrochloric Acid.
We, FARNHAM MAXWELL LYTE of 60, Finborough Road, London, S.W.,
Analytical Chemist, and OSCAR JULIAN STEINHART of 15, Bolton Gardens
West, London, S.W., Ph. D., do hereby declare the nature of this invention to be
as follows:-
The object of this invention is the recovery of the chlorine contained in the waste
liquor of the ammonia-soda process, but it may also be applied to the production of
chlorine from other residues.
Our invention is mainly based on the fact that chlorine and some hydrochloric
acid is evolved when magnesic chloride is heated in admixture with a suitable
manganite such as manganite of lime (Weldon mud) manganite of magnesia or any
other suitable manganite in the moist state, and we find that the yield of chlorine is
considerably increased if to the above mixture be added a suitable chloride or other
suitable hygroscopic bodies in equal or varied proportions (such as chlöride of
sodium. chloride of calcium. chloride of zinc, etc., etc.).
The reaction taking place in the generation of chlorine may be expressed as
Follow
The reaction taking place in the generation of chlorine may be expressed as
5 (MgCl,+6 H,O)+CaO, 2 MnO,, HgO+ CaCl=
(x+1)CaCl,+5 Mg(OH)2+4 C1+2 MnCl,+26 H₂O.
Whereas the decomposition of magnesic chloride into free chlorine and magnesia
is only effected at comparatively high temperatures (in a current of air or oxygen)
we on the contrary are able to work at a much lower temperature; the evolution
of chlorine commencing at about 150° C. and ending at say about 300° to 350° C.,
the mixture for the evolution of chlorine being preferably spread in thin layers,
thereby preventing the decomposed particles from acting as a non-conducting
medium.
We also find that the yield is further increased if the residue in the still, after
having ceased to evolve chlorine, is moistened with the HCl it gave off in con-
junction with the chlorine (and which HCl may be caught in a suitable condenser)
and heated over again as though it were a fresh batch of material for the production
of chlorine. Or again we may condense the HCl direct into the residue of a
previous operation (the said residue being by preference first allowed to cool) and
the acid from this into the residue of the operation last but one and' so on
until each residue becomes completely exhausted or the acid too weak to warrant
further use.
After the chlorine has been driven off, the residue consisting of say magnesia
chloride of manganese, chloride of sodium, chloride of calcium, and some magnesic
chloride, may be treated with water and boiled when it will be found (on cooling if
necessary) that most of the chloride of manganese has been precipitated as hydroxide
of manganese by a corresponding quantity of the magnesia which is always present
in excess with formation of magnesic chloride (or the residue may be allowed to
deliquesce being helped if necessary with a spray of water and the manganese
chloride and calcic chloride thus obtained be "blown" in the usual way with
formation of calcic chloride in solution and precipitation of Weldon mud). The
precipitation of manganese as hydrate may be formulated in the following way-

page_text: in a solution containing magnesic chloride, sodic chloride, calcic chloride, and some
chloride of manganese. This solution may now be filter-pressed off or otherwise
removed from its residue and boiled down to dryness when on further heating in
the presence of steam if necessary hydrochloric acid will be driven off from the
magnesic chloride say to the extent of 90%. This hydrochloric acid may be
condensed in a receiver and poured over the residue of magnesia and manganese
oxide (which oxide has, however, first been converted into Weldon mud by
blowing" etc.; or into manganite of magnesia by drying and heating in a current
of air in the usual way, preferably at a low temperature) thus once more converting
the magnesia into magnesic chloride to be employed for the further generation of
chlorine.
66
The residue of magnesia resulting from the evolution of hydrochloric acid, as
above shewn, may be employed for furthur converting the waste liquors of the
ammonia-soda process into magnesic chloride by adding the said magnesia to the
said liquors and gassing with carbonic acid the sodic chloride, calcic chloride, and
small amount of manganesic chloride contained being if desired first leached out
from the magnesia and added with the hydrochloric acid (obtained as above shewn)
to the magnesia and manganite, thus entering into the next operation for the
production of chlorine and forming part of the cycle of operations which becomes
complete when the requisite amount of magnesic chloride (obtained as above shewn
from the ammonia-soda waste liquor) has been added.
We find we can also produce chlorine by adding in the usual way hydrochloric
acid to a suitable manganite a strong hydrochloric acid being obtained by heating
magnesic chloride in combination with a suitable salt or salts, as above shewn ; and
this last method may further be varied by heating, according to the application for
Letters Patent No. 18240 of 1890, say magnesic chloride and nitrate of magnesia
together (other suitable salts being further added if necessary) and passing the
evolved gases through a solution (raised or lowered to any desired temperature)
containing binoxide or hydrated oxide of manganese or some suitable manganite,
when chlorine will be evolved with formation of nitrate and chloride of manganese
in solution.
Dated this 30th day of December 1890.
COMPLETE SPECIFICATION.
Improvements in the Production of Chlorine and of Strong
Hydrochloric Acid.
We, FARNHAM MAXWELL LYTE, of Finborough Road, London, S.W.
Analytical Chemist, and OSCAR JULIAN STEINHART, of Bolton Gardens
West, London, S.W., Ph. D. 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:-
This invention relates to the recovery of chlorine and of hydrochloric acid as a
bye product from hydrated magnesic chloride (obtained from waste chloride liquors
such as those of the ammonia-soda process or from any magnesic chloride artificial
or native) and the invention is mainly based on the fact that hydrochloric acid and
chlorine are evolved when magnesie chloride in the moist state is heated in
admixture with manganese dioxide produced in the wet way, the yield of chlorine
is far greater than when natural manganese dioxide or artificial dioxide produced
in the dry way is used; and upon the further fact that if the magnesic chloride be
first converted into what we term a "hygroscopic" double salt (double chloride of

page_text: magnesium and calcium for instance) strong hydrochloric acid is chiefly formed,
thereby still further increasing the yield of chlorine.
By manganese dioxide produced in the wet way, we mean dioxide left after
dissolving out the base from a manganite (such as Weldon mud) which has been
produced in the wet way.
By hygroscopic double salt is meant a salt which owing to its affinity for water
remains hydrated during the evolution of hydrochloric acid so that strong acid is
evolved.
The essentially novel features in the herein described process are, therefore-
(a) heating manganese dioxide produced in the wet way with hygroscopic
magnesic double chloride;
() repeatedly returning the evolved hydrochloric acid to the residues in the
chlorine still, and reheating, thereby ensuring the more complete decomposi-
tion of the manganese dioxide, avoiding waste of manganese and obtaining a
greater yield of chlorine;
(c) conducting the whole process of producing chlorine according to the
principal and secondary cycles of operations hereafter described, with the
objects of producing pure strong chlorine; and
(d) working at low temperatures.
We will describe in detail an example of the process as applied to the treatment
of waste calcic chloride liquors, in illustration whereof we append a graphic
description, indicating the various stages of treatment, wherein the feathered
arrows shew the course of the materials through the main cycle of operations and
the dotted featherless arrows denote the subsidiary cycles.
It must be understood that wherever waste calcic chloride is referred to, native
or waste magnesic chloride may be substituted as the source of the chlorine, in
which case the operation of "gassing" at B is unnecessary.
"
Assuming that we commence working with magnesia and manganese hydroxide
(both of which may be the residues of a previous operation) and some waste calcic
chloride liquors of the ammonia-soda process, as shewn at A, the first step is to
convert the manganese oxide into manganite and the magnesia into magnesic
chloride. We therefore, if necessary, add lime (or other base) and then "blow
with air in the usual way for the formation of Weldon mud or other manganite.
Sufficient dilute hydrochloric acid is then added to dissolve the lime in the Weldon
mud and the magnesia. The solution of magnesic and calcic chlorides is run into B
and the precipitate of manganese dioxide (2 MnO2) remaining behind, is taken to
the chlorine still at C.
To the magnesic and calcic chloride solution at B we add soft burnt magnesia
(resulting from the decomposition of part of the magnesic chloride as hereafter
described) and then proceed to "gas" with carbon dioxide (CO2) lime kiln gas for
example, thus precipitating calcic carbonate (3 CaCO3) which goes to and forming
more magnesic chloride making 5 MgCl, in all.
Two-fifths of this magnesic chloride are run, along with an equal quantity of
magnesic chloride coming from a previous operation, into the chlorine still at C to
form with the manganese dioxide from A. a fresh batch of material for production
of chlorine.
To this batch of magnesic chloride (4 MgCl2) + manganese dioxide (2 MnO2)+
water (4 H2O) we add a chloride, such as potassic or calcic chloride for instance,
which will form with magnesic chloride a hygroscopic double salt with the object
of enabling strong hydrochloric acid to be formed which, in virtue of its strength,
will convert more of the manganese dioxide present into manganesic chloride with
evolution of chlorine than a weak acid would.
G
The chlorine still C which may be gradually heated to about 300° C. leads into a
condenser where any hydrochloric acid given off is caught and through which the
evolved chlorine passes as strong undiluted chlorine into c'. The hydrochloric
acid caught in the condenser c is to be poured over the residue or partly-spent

page_text: mass remaining in the chlorine still C and the mass then reheated for the production
of more hydrochloric acid and chlorine, and this operation of returning the evolv.ed
hydrochloric acid to the residue and reheating may be repeated over and over
again until chlorine ceases to be evolved in paying quantity. Or the hydrochloric
acid instead of being condensed in a separate condenser may be condensed direct in
the residue of one or more previous operations in another still.
The exhausted residue from C, with the addition of sufficient water, is boiled
at D whereby about. 80% to 90% of the chloride of manganese will be con-
verted into magnesic chloride by part of the magnesia, manganese hydroxide being
precipitated.
We therefore have in solution about two molecules of magnesic chloride, the
hygroscopic double salt mentioned and a small percentage of manganese chloride.
These liquors are filter-pressed off from their precipitate and run back into C along
with a further quantity of magnesic chloride coming from a subsequent operation.
E represents the residual precipitate from D and consists of magnesia and all the
manganese originally employed in C less the 10% to 20% which, not being
precipitated on boiling in D, will be constantly circulating as manganese chloride
between C and D.
The magnesia and manganese oxide from D then go to A (which completes the
main cycle of operations) where with the addition of a further quantity of calcic
chloride liquor and lime (or other base) a fresh cycle is commenced by "blowing"
with air for the formation in the wet way of a fresh batch of manganite.
The remaining three-fifths of magnesic chloride from B goes to B₁ where it is
decomposed by heat and addition of steam or a spray of water or of a solution of
calcic or other chloride forming with magnesic chloride a hygroscopic double salt,
the resulting hydrochloric acid going to A to neutralize the lime and magnesia in
the manganite and thus isolate manganese dioxide, whilst the resulting soft burnt
magnesia returns to B for the formation, by "gassing" as before described, of more
magnesic chloride, the 3 MgO representing a constant quantity, performing the
subsidiary cycle from B to B and back to B.
It will be observed at each principal cycle of operations a fresh lot of waste
calcic chloride liquor is brought into play in A, thus serving both to supply more
calcic chloride if necessary in order to "blow" Weldon mud and as the source of
the chlorine which goes as magnesic chloride (2 MgCl2) to C and which ultimately
appears as our final product chlorine (4 Cl) in e' as before described.
Should it be found that a larger quantity than two molecules of calcic chloride is
requisite for "blowing" purposes in A such excess will require a larger quantity of
soft burnt magnesia for "gassing" purposes in B. The production of this larger
quantity of magnesia will perforce bring about an increase in hydrochloric acid
at B and we should have too much hydrochloric acid were it not that the same
can be neutralized in b, the calcic chloride thus produced being used as well as the
carbon dioxide evolved. Or the calcic chloride may be washed out or drawn off
from the precipitate in A, before addition of hydrochloric acid from B'.
+6
A variation of our process would be to allow the manganese chloride in the
residue of C (after evolution of chlorine) to slowly deliquesce out in the cold,
assisting it, if necessary, with a spray of water or calcic chloride solution. This
manganese chloride would then be
blown "
as above described at A to form
Weldon mud and the calcic chloride left in solution or part thereof "gassed" with
carbon dioxide in presence of the precipitate of magnesia left in C after the
deliquescence of the manganese chloride. Magnesic chloride would thus be pro-
duced and, mixed with the Weldon mud, would evolve chlorine as above shewn..
The following is a further variation: In order to avoid the use of decimals,
we double the quantities we give above and we will suppose that, instead of
2.5 CaCl, +5 MgCl₂+2 MnO2+aq, we start with 5 CaCl,+ 10 MgCl₂+4 MnO2+aq.
On heating this mixture as already described 8 Cl are evolved and there remain in
the still 5 CaCl, +8 Mg0+2 MgCl₂+ MnCl. These being broken up.in water

page_text: 27
e add 8 CaO and "blow to form Weldon mud when we obtain 2 CaO(MnO,),
Weldon mud)+10 MgO as a precipitate and 11 CaCl, in solution. We allow the
ixture to settle partially and draw off 8 CaCl, leaving 3 CaCl, still in the mixture
nd then we add dilute HCI in sufficient quantity to dissolve and saturate the
ases present. Thus is re-formed the mixture 5 CaCl2 + 10 MgCl₂+4 MnO2 which
e began with, and so we are ready to commence another operation.
The proportions throughout above given are the theoretical ones; in practice
may be found necessary to vary them, more or less.
Having now particularly described and ascertained the nature of the said
vention and in what manner the same is to be performed, we declare that what
e claim is
1st. The herein described process of producing chlorine and hydrochloric acid
om magnesic chloride obtained from waste chloride liquors or from other chlorides,
ubstantially as specified.
2nd. The herein described process of producing strong chlorine and hydrochloric
cid from magnesic chloride obtained from waste chloride liquors or from other
hlorides, which process consists in the following main and subsidiary cycles of
perations, namely
-
(a) Treating manganese hydroxide (the residue from a previous operation) by
"blewing" in the presence of magnesia and the waste chlorides and of lime
(or other suitable base) to form Weldon mud or other manganite in the wet
way; then adding hydrochloric acid to isolate manganese dioxide (which
goes to the chlorine still) adding soft burnt magnesia (produced in opera-
tion b) to the mixed chlorides and "gassing" with carbon dioxide (according
to the Schaffner-Helbig process) to convert the calcic chloride into magnesic
chloride; then forming a hygroscopic double chloride with part of the
magnesic chloride and heating it along with manganese dioxide and water to
distil off chlorine and hydrochloric acid; then repeatedly returning the acid
to the residue (of this or another similar operation) and re-distilling; then
boiling the exhausted residue with water to form magnesic chloride (which
is returned along with contained calcic chloride and some undecomposed
manganesic chloride, to the chlorine still) and precipitate magnesia and
manganese hydroxide, thus completing the cycle of operations, as herein
specified.
(6) Decomposing the remainder of the magnesic chloride, produced as above
specified, to form hydrochloric acid and soft-burnt magnesia and adding the
former to the manganite and the latter to the mixed chlorides in operation a,
as specified.
3rd. In the herein described process of producing chlorine, as specified in Claim 1,
eating magnesic chloride in the presence of water and of manganese dioxide which
as been isolated by neutralizing with hydrochloric acid the base or bases combined
ixed with or contained in Weldon mud or other manganite produced in the
et way, substantially as described.
4th. In the herein described process of producing hydrochloric acid and chlorine, as
pecified in Claim 1, the distillation of hygroscopic magnesic double chloride with
hanganese dioxide which has been obtained from Weldon mud or other maganite
roduced in the wet way, whereby a larger production of chlorine is obtained, as
pecified.
5th. In the herein described process of producing chlorine and hydrochloric acid,
s specified in Claim 1, the method of repeatedly returning to the residue in the
hlorine still the hydrochloric acid distilled from hygroscopic magnesic double
hloride in the presence of manganese dioxide and water and re-distilling such
esidue and acid for the production of more chlorine, as specified.
6th. In the herein described process of producing hydrochloric acid and chlorine,
s specified in Claim 1, boiling the exhausted residue from the chlorine still with
ater and contained or added magnesia, to precipitate manganese hydroxide and

page_text: form magnesic chloride and re-converting, in the wet way, the manganese hydroxide
into Weldon mud or other manganite by "blowing" the hydroxide in the presence
of magnesia, waste chloride liquor, and lime or other suitable base, as specified.
Dated this 30th day of September 1891.
F. MAXWELL LYTE.
O. J. STEINHART.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.