Improvements in the Manufacture of Anhydrous Chloride of Magnesium and in the Production of Chlorine therefrom.
Year: 1889

page_text: Date of Application, 13th Mar, 1889
Complete Specification Left, 13th Rec., 1889-Accepted, 25th Jan., 1890
PROVISIONAL SPECIFICATION.
[Communicated from abroad by Messrs. SOLVAY and Co., of 19, Rue du Prince
Albert, Brussels, Belgium, Manufacturers.]
Improvements in the Manufacture of Anhydrous Chloride of
Magnesium and in the Production of Chlorine therefrom.
1, WILLIAM LLOYD WISE of No. 46 Lincolns Inn Fields, in the County of Middlesex,
Consulting Engineer and Patent Agent, do hereby declare the nature of this invention
to be as follows:-
There are several processes known for obtaining chlorine in a free state from
chloride of magnesium. These processes have as a common feature the heating, in
the solid state, and in the presence of a current of air, of chloride of magnesium mixed
with magnesia.
The principal difficulty to be overcome in these processes, is caused by the
pulverulent condition assumed by the material during its decomposition, which
condition does not allow of the use of heating apparatus of simple construction.
Further, there has to be heated and manipulated a mass of magnesia which is
merely added to serve as support and does not itself yield chlorine.
This invention relates to an improved process which obviates the disadvantages
mentioned, and according to which there is treated not a mixture of chloride of
magnesium and magnesia, but anhydrous chloride of magnesium (Mg Cl³) alone.
This chloride of magnesium, which is fusible at a relatively low temperature, is
treated with hot air, not whilst it is in the solid state, but whilst it is in a fluid state
caused by igneous fusion."
።
The improved process comprises two stages: First, the preparation of anhydrous
chloride of magnesium, and-Second, the production therefrom of chlorine.
The anhydrous chloride of magnesium is prepared from the chloride of magnesium
of commerce which is a concentrated solution or the crystallized salt which contains
six equivalents of water which can be readily removed.
This chloride of magnesium (Mg Cl2 6 H2 O) is heated in a current of air at a
temperature below 120° C.-It can thus be brought to a richness of 80 per cent. of
anhydrous salt without melting and without giving off any hydrochloric acid. When
once brought to this point, it can withstand, without fusion, a higher temperature
and it may be deprived of almost the whole of its water of crystallization.
During the first part of the operation the point of fusion is very nearly reached,
so. that the dessication is thus rendered very delicate and requires considerable
In order to render this operation more practicable the following process is
care.
adopted.
A hot solution of hydrated chloride of magnesium, containing its six equivalents
of water, and therefore capable of being entirely crystallized, by cooling, to the
condition of Mg Cl² 6 H2O, is taken and with it is incorporated a certain amount
(say, 50 per cent.) of anhydrous salt Mg Cl³, obtained from a previous operation.
The mixture is then cooled and a compact mass is obtained which is broken into
pieces, and which can then be raised by a current of heated gas, such as air, to a
temperature of 300 or 400 degrees C. without melting, in a vertical and continuous-
action apparatus. The original salt, on the contrary, would melt at 115° C.-The
anhydrous chloride may be incorporated with the hydrated chloride of magnesium
'when this is in the crystallized state.
The current of air employed, is first dried by suitable means such as sulphuric
acid or chloride of calcium. It removes the water in the state of vapour from the
chloride of magnesium, the proportion of water being generally less than that
normally contained in air. The heat carried off by the air may be utilized by using

page_text: the said air over again after having dried it, which may be done without lowering its
temperature to any considerable extent. As the same air may be thus employed over
again in a cycle, and as it merely acts as a vehicle or carrier of water it will be seen
thut the process renders possible the employment of another gas if required in lieu
of air.
To obtain chlorine from the anhydrous chloride of magnesium obtained in the
above or in any other suitable manner, this salt is liquefied by "igneous fusion"
and subjected whilst at a red heat to the action of a current of air.
This may be done in various ways. The molten chloride of magnesium may be
drawn or forced along by means of a current of superheated air, which pulverizes it
into the form of small drops or spray. The conversion of the salt into chlorine and
magnesia is instantaneous, the magnesia being deposited in the reaction chamber, and
the chlorine drawn off. Or the molten chloride of magnesium may be caused to
circulate in an atmosphere capable of yielding to it the requisite oxygen.
It is however considered advantageous to proceed in the following manner. The
chloride of magnesium is melted in a cruciblo or by preference in a vessel resembling
a Bessemer converter, either by the exterior application of heat, or preferably by the heat
supplied by the current of air which enters by a lower tuyere or a "bubbling tube."
In any case however the current should not enter through the bottom of the vessel,
as a zone of quiet fusion should be left underneath the air inlet. The magnesia
formed by the action of the air on the molten chloride is dense, and precipitates
readily on the bottom of the vessel whence it can be removed by scooping it out
or preferably by allowing it to flow out through a tap hole, as in a cupola. The
magnesia thus obtained is mixed with a small quantity of chloride of magnesium
which impregnates it in a manner similar to that in which mother liquors impregnate
crystals or mud but it may be readily freed from the chloride by washing unless it
is preferred to treat the mixture for the extraction of chlorine by any known
methods.
The current of chlorine gas obtained has a per centage of 15 to 20% and in
contradistinction to other processes, this per centage is maintained invariable, instead
of diminishing from the beginning to the end of the operation for the composition of
the matters in presence does not change. The process may be carried on continuously
by adding as much chloride of magnesium to the bath as magnesia is removed in
the form of mud.
Air might be injected into the bath until a decomposition be obtained as complete
as the fluidness at red beat would allow and then coinmence again after completely
emptying the vessel of the magnesia residue, yet it is preferred to carry on the
operation continuously in the manner above indicated.
Dated this 13th day of March 1880
W. LLOYD WISE.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Anhydrous Chloride of
Magnesium and in the Production of Ohiorine therefrom.
1, WILLIAM LLOYD WISE, of No. 46, Lincoln's Inn Fields in the County of
Middlesex, Consulting Engineer and Patent Agent, 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 :-
There are several processos known for obtaining chlorine in a free state from
chloride of magnesium. These processes have as a common feature the heating, in the
solid state, and in the presence of a current of air, of chloride of magnesium mixed &
with magnesia.
The principal difficulty to be overcome in these processes is caused by the pulverulent
condition assumed by the material during its decomposition, which condition does not
allow of the use of heating apparatus of simple construction.

page_text: Further, there has to be heated and manipulated a mass of magnesia which is merely
added to serve as a support and does not itself yield chlorine.
This invention relates to an improved process which obviates the disadvantages
mentioned and according to which there is treated not a mixture of chloride of
magnesium and magnesia, but anhydrous chloride of magnesium (Mg C³) alone.
This chloride of magnesium, which is fusible at a relatively low temperature, is treated
with hot air, not whilst it is in the solid state, but whilst it is in a fluid state caused
by "igneous fusion."
The improved process comprises two stages: First, the preparation of anhydrous
chloride of magnesium, and Second, the production therefrom of chlorine.
The anhydrous chloride of magnesium is prepared from the chloride of magnesium
of commerce which is a concentrated solution, or from the crystallized salt which
contains six equivalents of water which can be readily removed.
This chloride of magnesium (Mg Cl³, 6 H2 O) is heated in a current of air at a
temperature below 120° C. It can thus be brought to a richness of 80 per cent. of
anhydrous salt without melting and without giving off any hydrochloric acid. When
once brought to this point, it can withstand, without fusion, a higher temperature and
it may be deprived of almost the whole of its water of crystallization. During the
first part of the operation the point of fusion is very nearly reached, so. that the
dessication is thus rendered very delicate and requires considerable care.
to render this operation more practicable the following process is adopted.
In order
A hot solution of hydrated chloride of magnesium containing its six equivalents of
water, and therefore capable of being entirely crystallized, by cooling, to the condition
of Mg C, 6 H2 O, is taken and with it is incorporated a certain amount (say
50 per cent.) of anhydrous salt, Mg Cl³, obtained from a previous operation. The
mixture is then cooled and a compact mass is obtained which is broken into pieces,
and which can then be raised by a current of heated gas such as air, to a temperature
of 300 or 400 degrees C. without melting, in a vertical and continuous action apparatus.
The original salt, on the contrary, would melt at 115° C. The anhydrous chloride
may be incorporated with the hydrated chloride of magnesium when this is in the
crystallized state.
The current of air employed, is first dried by suitable means such as sulphuric acid
or chlorido of calcium. It removes the water in the state of vapour from the
chloride of magnesium, the proportion of water in the air being generally less than
that normally contained in air. The heat carried off by the air may be utilized by
using the said air over again after having dried it, which may be done without
lowering its temperature to any considerable extent. As the same air may be thus
employed over again in a cycle, and as it merely acts as a vehicle or carrier of water
it will be seen that the process renders possible the employment of another gas if
required in lieu of air.
To obtain chlorine from the anhydrous chloride of magnesium obtained in the
above or in any other suitable manner, this salt is liquefied by "igneous fusion" and
subjected whilst at a red heat to the action of a current of air.
This may be done in various ways. The molten chloride of magnesium may be drawn
or forced along by means of a current of superheated air, which pulverizes it into
the form of small drops or spray. The conversion of the salt into chlorine and
magnesia is instantaneous, the magnesia being deposited in the reaction chamber, and
the chlorine drawn off. Or the molten chloride of magnesium may be caused to
circulate in an atmosphere capable of yielding to it the requisite oxygen.
It is however considered advantageous to proceed in the following manner.
The
chloride of magnesium is melted in a crucible or by preference in a vessel resembling
Bessemer converter, either by the exterior application of heat, or preferably by the
heat supplied by the current of air which enters by a lower tnyere or a "bubbling
tube."
In any case however the current should not enter through the bottom of the
vessel, as a zone of quiet fusion should be left underneath the air inlet. The magnesia
formed by the action of the air on the molten chloride is dense, and precipitates
readily on the bottom of the vessel whence it can be removed by scooping it out or

page_text: preferably by allowing it to flow or pass out through a tap hole, as in a cupola. The
imagnesia thus obtained is mixed with a small quantity of chloride of magnesium
which impregnates it in a manner similar to that in which mother liquors impregnate
crystals or mud, but it may be readily freed from the chloride by washing unless it
is preferred to treat the mixture for the extraction of chlorine by any known
methods.
The current of chlorine gas obtained bas a percentage of 15 to 20% and in
contradistinction to other processes, this per centage is maintained invariable, instead
of diminishing from the beginning to the end of the operation for the composition of
the matters present does not change. The process may be carried on continuously
by adding as much chloride of magnesium to the hath as magnesia is removed in the
form of mud.
Air might be injected into the bath until a decomposition be obtained as complete
as the fluidness at red heat would allow and then commence again after completely
emptying the vessel of the magnesia residue, yet it is preferred to carry on the
operation continuously in the manner above indicated.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In the manufacture of anhydrous chloride of magnesium, for use in the
production of chlorine, the mixing with hydrated chloride of magnesium in the form
of crystals or aqueous solution, of anhydrous chloride of magnesium for the purpose of
preventing the liquefaction of the product when the latter is dessicated by a current
of heated air or other gas.
2. The production of chlorine by bringing anhydrous chloride of magnesium in. a
liquid state produced by igneous fusion, into intimate contact with a gas containing
oxygen such as air.
Dated this 12th day of Dunombor 1880