Improvements in Decomposing Liquors Containing Chloride of Magnesium.
Year: 1885

page_text: PROVISIONAL SPECIFICATION.
Improvements in Decomposing Liquors Containing Chloride of
Magnesium.
I, JAMES WILSON, of the North of England Chemical Works in the County and
Town of Berwick-on-Tweed, Manufacturing Chemist do hereby declare the nature
of the said invention for IMPROVEMENTS IN DECOMPOSING LIQUORS CONTAINING
CHLORIDE OF MAGNESIUM to be as follows:-
In the Complete Specification of Patent No 5975 applied for by me in the
year 1884 for Improvements in the Manufacture of Chlorate of Potash there is
given a process for decomposing the solution of chloride of magnesium remaining
as a mother-liquor after the crystallization of the Chlorate of Potash.
This process
consists in evaporating the mother-liquor (that is to say the solution of chloride of
magnesium) till a sample, on cooling, solidifies, and then running it preferably in a
constant stream into a Muffle Furnace, reducing it to dryness and then heating the
residue to redness, a small quantity of magnesia having previously been placed on
the bed of the furnace to prevent the chloride of magnesium adhering thereto.
My present Improvements relate to the application of this method of decomposing
chloride of magnesium, with such modifications and additions as are hereinafter set
forth, to liquors containing chloride of magnesium from whatever source these
liquors may have come (other than the mother-liquors from the above mentioned
process of making chlorate of Potash) and whether they consist of a solution of
chloride of magnesium alone or liquor containing chloride of magnesium mixed
with other substance or substances.
•
In all previous methods of decomposing chloride of magnesium by heating it in
Muffle Furnaces, which have come to my knowledge, there have been these
drawbacks that the chloride of magnesium if introduced into the Furnace in a
liquid state soaked through the Furnace bed, or if introduced in a solidified state,
it melted and became liquified. In either case the liquid or melted chloride of
magnesium on becoming decomposed or partially decomposed left a residue which
adhered with such tenacity to the Furnace bed that it was difficult of removal, and
which was of such a dense nature that the complete decomposition of the chloride
of magnesium contained in it was very slow and difficult. The chloride of

page_text: magnesium also has always hitherto been introduced into the Furnace intermittently,
and in large quantities at a time which has further had the effect of cooling the
Furnace to an undue extent.-The result of the chloride of magnesiumn being
allowed to soak through the Furnace bed, and the residue of the decomposition
of the chloride of magnesium adhering thereto, and the cooling of the Furnace
brought about by large quantities of liquid being introduced when the Furnace
was at its hottest, was that the Furnaces were rapidly destroyed, besides the
decomposition of the chloride of magnesium being very difficult and unsatisfactory.
Now my object is to remove these drawbacks by introducing the liquor con-
taining the chloride of magnesium into the Furnace in a constant gentle stream, or
as gently and constantly as possible, and causing the liquor containing the chloride
of magnesium to be absorbed as it enters the Furnace by a suitable absorbing
medium, as will hereafter be set forth.
In effecting this object, the liquor to be decomposed consisting of a solution
of chloride of magnesium mixed or not with other substance or substances is
evaporated to a temperature of about 300° Fahrenheit, or until a sample on
cooling, solidifies well. This concentrated solution (which will hereafter be spoken
of as concentrated liquor) is then run, in as constant and gentle a stream as
possible, into a muffle or other furnace or vessel wherein it may be heated until
the desired result is attained. As the concentrated liquor runs into the Furnace or
vessel it is mixed with a suitable absorbing agent sufficient to take it up and
prevent it soaking through the Furnace beds.
Many substances will occur to a practical chemist as being suitable for this
purpose such as Oxide of Iron or substances of a silicious or aluminous nature, but
where the magnesia produced by the decomposition of the chloride of magnesium
operated upon is to be used in a subsequent operation such substances would not
be generally admissible unless they be contained in the solution containing the
chloride of magnesium or are produced by the decomposition of substances con-
tained therein, and I prefer that the substance used for absorbing the concentrated
liquor should be the product of the decomposition or partial decomposition of the
concentrated liquor resulting from a former operation. When the liquor to be
decomposed consists only of chloride of magnesium, this will of course be Magnesia.
When the liquor consists of chloride of magnesium mixed with chloride of sodium,
the absorbing agent will be magnesia mixed with chloride of sodium and such
chloride of magnesium as may have escaped decomposition. When the liquor
consists of chloride of magnesium mixed with chloride of manganese, the absorbing
agent will be magnesia mixed with oxide of Manganese, and so on.
When the absorbing agent is saturated with concentrated liquor it may be
removed and a further quantity of absorbing agent placed so as to take up the
liquor running in. The portion of absorbing agent so saturated may be dried and
the dried material may then be further heated till the desired result is attained, or
it may be used to take up a further portion of concentrated liquor.
I have mentioned that the concentrated liquor may be run into a Muffle or other
Furnace or vessel wherein it may be heated till the desired result is attained.
When using a Muffle or closed Furnace or vessel it is of course understood that air
must be admitted into such Furnace or vessel. A sufficient quantity of air will
usually be found to enter by the Furnace doors, but in some cases, especially where
the chloride of magnesium is associated with chloride of manganese, it will be
found advantageous to heat the air, and a further advantage will be found in
having the Furnace rather long.
I also mean it to be understood that it is best to run the concentrated Liquor
into the coolest part of the Furnace, and to move the mixture of concentrated liquor
and absorbing Agent or product of the decomposition or partial decomposition
thereof gradually towards the hottest part of the said Furnace.
Instead of using a muffle or closed furnace or vessel and applying the heat to the
outside thereof, the charge may be directly heated by the action of superheated air.

page_text: In either case, that is to say whether the charge be heated in a Muffle Furnace as
above described, or by means of superheated air, the chlorine will be evolved to
a considerable extent in the free state, and may be freed from the Hydrochloric
acid accompanying it by the usual method of condensation as will be well
understood.
When obtaining as much Chlorine in the free state is not an object, however,
other means of heating the charge may be used such as superheated steam or a
suitable gaseous fuel, but no particular means of heating it forms any part of this
Invention.

page_text: COMPLETE SPECIFICATION.
Improvements in Decomposing Liquors Containing Chloride of
Magnesium.
I, JAMES WILSON of the North of England Chemical Works in the County
and Town of Berwick-upon-Tweed, Chemist do hereby declare the nature of my
said invention for IMPROVEMENTS IN DECOMPOSING LIQUORS CONTAINING CHLORIDE
OF MAGNESIUM and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
In the Specification of Patent No. 5975 A.D. 1884 granted to me for "Improve-
ments in the manufacture of Chloride of Potash" there is given a process for
decomposing the solution of Chloride of Magnesium remaining as a mother-liquor
after the crystallization of the Chlorate of Potash. This process consists in
evaporating the mother-liquor (that is to say the solution of Chloride of
Magnesium) till a sample on cooling, solidifies, and then running it, preferably in a
constant stream into a muffle furnace, reducing it to dryness and then heating the
residue to redress, a small quantity of magnesia having previously been placed on
the bed of the furnace to prevent the Chloride of Magnesium adhering thereto.
My present improvements relate to the application of this method of decom-
posing Chloride of Magnesium with such modifications and additions as are
hereinafter set forth, to liquors containing chloride of magnesium from whatever
source these liquors may have come (other than the mother-liquors from the above
mentioned process of making Chlorate of Potash) and whether they consist of a
solution of chloride of magnesium alone, or liquors containing chloride of magnesium
mixed with other substance or substances.
In all previous methods of decomposing Chloride of Magnesium by heating it in
muffle furuaces which have come to my knowledge there have been these drawbacks
that the Chloride of Magnesium if introduced into the furnace in a liquid state,
soaked through the furnace beds, or if introduced in a solidified state, it melted
and became liquified. In either case the liquid or melted Chloride of Magnesium,
also, on becoming decomposed or partially decomposed left a residue which adhered
with such tenacity to the furnace bed as to be difficult of removal, and which was
of such a dense nature that the complete decomposition of the Chloride of Mag-
nesium contained in it was very slow and difficult. The Chloride of Magnesium
also has always hitherto been introduced into the furnace intermittently, and in
large quantities at a time, which has further had the effect of cooling the furnace
to an undue extent. The result of the Chloride of Magnesium being allowed to
soak through the furnace bed, and the residue of the decomposition of the Chloride
of Magnesium adhering thereto, and the cooling of the furnace brought about by
large quantities of liquid being introduced when the furnace was at its hottest was
that the furnaces were rapidly destroyed, besides the decomposition of the Chloride
of magnesium being very unsatisfactory.

page_text: Now my object is to remove these drawbacks by introducing the liquor con-
taining the Chloride of Magnesium into the furnace in a constant gentle stream, or
as gently and constantly as possible, and causing it to be absorbed as it enters the
Furnace by a suitable absorbing medium, as will be hereafter set forth.
In effecting this object, the liquor to be decomposed, consisting of a solution of
Chloride of Magnesium mixed or not with other substance or substances is.
evaporated to a temperature of about 300° Fahrenheit, or until a sample on cooling,
solidifies well. This concentrated solution (which will hereafter be spoken of as
concentrated liquor) is then run, in as constant and gentle a stream as possible into
a muffle or other furnace or vessel wherein it may be heated until the desired
result is attained. As the concentrated liquor runs into the furnace or vessel it is
mixed with a suitable absorbing agent sufficient to take it up and prevent it
soaking through the furnace bed.
When
Many substances will occur to a practical chemist as being suitable for this
purpose such as Oxide of Iron, or substances of a silicious or aluminous nature,
but such substances would not be generally admissible unless they be contained
in the solution containing the chloride of magnesium, or are produced by the
decomposition of substances contained therein; and I prefer that the substance used
for absorbing the concentrated liquor should be the product of the decomposition,
or partial decomposition of the concentrated liquor of a former operation."
the liquor to be decomposed consists only of Chloride of Magnesium, this will be
magnesia or a mixture of Magnesia and Chloride of Magnesium. When the liquor
contains other substances besides the Chloride of Magnesium, such as Chloride of
Sodium, or Chloride of Manganese, the absorbing agent will be magnesia, or a
mixture of Magnesia and Chloride of Magnesium, with Chloride of Sodium or
Oxide of Manganese as the case may be ; and so on.
If the liquor to be decomposed contains much Chloride of Sodium, a considerable
part of it will become insoluble and be deposited during the evaporation, and may
be removed by any suitable means.
When the absorbing agent is saturated with concentrated liquor it may be
removed and a further quantity of absorbing agent placed so as to take up the
liquor running into the furnace. The portion of absorbing agent so saturated may
be dried, and the dried material may then be further heated till the desired result
is attained, or it, or part of it may be used to take up a further portion of
concentrated liquor.
In evaporating the liquor I prefer to use a series of vessels or one long vessel
divided into several compartments and to run it constantly through from vessel to
vessel, or from division to division becoming more and more concentrated in its
passage until it arrives at the last one in which it should always be as near
300° Fahrenheit as possible, and from which it is run into the furnace. It is best,
I think, to run the concentrated liquor into the coolest part of the furnace, and to
move the mixture of concentrated liquor and absorbing agent, or product of the
decomposition, or partial decomposition thereof gradually towards the hottest part of
said furnace. When using a muffle or closed furnace or vessel, it is of course under-
stood that air must be admitted thereinto, but instead of using a muffle or closed
furnace or vessel, and applying the heat to the outside thereof, the charge may be
directly heated by the action of superheated air. In either case the Chlorine will
be evolved to a considerable extent in the free state and may be freed from the
Hydrochloric Acid and steam accompanying it by the usual method of condensation
and drying as will be well understood.
When conducting the operation in a muffle furnace as above described I have
found that in a liquor containing only Chloride of Magnesium, the quantity of
Chlorine evolved in the free state is about one third of the total quantity contained
in the Chloride of Magnesium. In a mixture of Chloride of Magnesium and
Chloride of Manganese the proportion of Chlorine evolved as such is slightly
larger.

page_text: When obtaining as much Chlorine as possible in the free state is not an object
however, other means of heating the charge may be used, such as superheated
steam, or a suitable gaseous fuel, but no particular means of heating it forms any
part of this Invention.
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed, I declare that what
I claim is
First. Decomposing liquors containing Chloride of Magnesium by running the
concentrated solution of such liquors into a muffle or other furnace or vessel in a
continuous stream.
.
Second. Mixing such solution, as it runs into the furnace or vessel, with a
suitable absorbing agent.