IMPROVE- MENTS IN THE MANUFACTURE OF CHLORINE
Year: 1884

page_text: I, THOMAS MACFARLANE of Montreal in the Province of Quebec and Dominion
of Canada at present residing at Coatbridge in the County of Lanark, North
Britain, Chemist do hereby declare the nature of said Invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF CHLORINE" to be as follows:-
I first prepare protochloride of manganese by evaporating to dryness in suitable
vessels the residual liquor produced by dissolving peroxide of manganese in
hydrochloric acid in order to the production of Chlorine. This dry protochloride
of manganese I reduce to powder and mix it with a proportion of dry powdered
peroxide of iron varying from one to four times the weight of the Chloride of
Manganese. I then introduce the mixture into a muffle furnace or "blind roaster"
which may resemble that used in calcining pyrites cinders with salt, in the process
of Copper extraction. In this furnace or roaster I expose the mixture to a
temperature of about 400° Centigrade and at the same time cause a current of dry
air to pass over it. The air may be dried by passing it through Chloride of
Calcium preferably contained in underground passages or Canals. The charge in
the furnace or roaster is frequently stirred so as to prevent sintering and allow
access of air. The chloride of manganese is under these circumstances completely
converted into sesquioxide or peroxide of manganese (which remains with the
peroxide of iron in the furnace) and Chlorine gas which is evolved. The
decomposition is perfect for the oxides remaining in the furnace contain little or no
soluble manganese. The Chlorine gas is of course mixed with nitrogen and with
whatever excess of atmospheric air that may have been used. It may also contain
hydrochloric acid if the materials and air have not been thoroughly dried. To
remove any such hydrochloric acid the Chlorine and accompanying gases are first
conducted through a cooler in which they meet a spray shower, and they are then
brought into contact with hydrate of lime which absorbs the Chlorine and bleaching
powder is thus produced.
The mixture of oxides remaining in the furnace is either in the same, or in
separate stills such as are used for the production of Chlorine, heated with an
amount of hydrochloric acid corresponding to the quantity of sesquioxide or
peroxide of manganese which it contains. The acid attacks the oxides of manganese
producing Chlorine which is made use of in the usual way for manufacturing

page_text: bleaching powder, while the peroxide of iron contained in the mixture remains for
the most part unchanged. The mixture resulting from this operation of peroxide
of iron with solution of protochloride of manganese is dried and heated in a muffle
furnace as above described when the Chloride of manganese is again decomposed
and Chlorine produced. This round of operations may be continued indefinitely no
new oxides being introduced excepting that. part which has been unavoidably lost,
and only fresh hydrochloric acid used, the whole of the Chlorine contained in which
is thus made available for the manufacture of Chlorine and bleaching powder.

page_text: I, THOMAS MACFARLANE of Montreal in the Province of Quebec and Dominion
of Canada at present residing at Coatbridge in the County of Lanark, North
Britain Chemist do hereby declare the nature of my invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF CHLORINE" and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement :―
I first prepare protochloride of Manganese by evaporating to dryness, in suitable
vessels, the residual liquor produced by dissolving peroxide of manganese in
hydrochloric acid in order to effect the production of Chlorine. This dry
protochloride of manganese I reduce to powder and mix it with any suitable
proportion of dry powdered peroxide of iron say for example a proportion varying
from one to four times the weight of the chloride of manganese I then introduce
the mixture into a muffle furnace or "blind roaster" which may conveniently
resemble that used in calcining pyrites cinders with salt in the process of copper
extraction. In this furnace or roaster I expose the mixture to a temperature of
about 400° Centigrade and at the same time cause a current of dry air to pass over
it. The air may be dried by passing it through chloride of calcium preferably
contained in under ground passages or canals. The charge in the furnace or roaster
is frequently stirred so as to prevent sintering and allow access of air. The
chloride of manganese is, under these circumstances, converted into sesquioxide or
peroxide of manganese (which remains with the peroxide of iron in the furnace)
and chlorine gas which is evolved. The decomposition is complete, for the oxides
remaining in the furnace contain little or no soluble manganese. The chlorine gas
is, of course, mixed with nitrogen and with whatever excess of atmospheric air
may have been used. It may also contain hydrochloric acid, if the materials and
air have not been thoroughly dried. To remove any such hydrochloric acid, the
chlorine and accompanying gases are first conducted through a cooler in which
they meet with water in the form of spray, and they are then brought into contact
with hydrate of lime which absorbs the chlorine, and bleaching powder is
produced.
The mixture of oxides remaining in the furnace is either in the same, or in
separate stills such as are used for the production of chlorine, heated with a
quantity of hydrochloric acid corresponding to the amount of sesquioxide or
peroxide of manganese which it contains. The acid attacks the oxides of manganese
producing chlorine, which is made use of in the usual way for manufacturing
bleaching powder, while the peroxide of iron contained in the mixture remains for
the most part un-changed. The mixture (resulting from this operation) of peroxide
of iron with solution of protochloride of manganese is dried and heated in a muffle
furnace, as above described, when the Chloride of manganese is again decomposed
and chlorine produced. This round of operations may be continued indefinitely no
new oxides excepting an amount equal to that which has been unavoidably lost
being introduced, and only fresh hydrochloric acid used, the whole of the chlorine
contained in which is made available for the manufacture of chlorine and bleaching
powder.

page_text: I am aware that it has been proposed to produce chlorine from the decom-
position of dry chloride of manganese, by heating it in contact with atmospheric
oxygen and other substances, but such plans have not been heretofore successful
owing the the difficulty of obtaining a complete decomposition. This I effect by the
use of the peroxide of iron, as above described, which renders the charge more
porous, and allows the atmospheric oxygen to permeate the mass and effect the
decomposition of the chloride of manganese. The peroxide of iron exercises also a
catalytic action in taking up oxygen from the atmosphere and transferring it to the
manganese. I desire therefore to state that I do not broadly claim producing
chlorine from chloride of manganesc. In carrying out the process according to my
Invention I do not confine myself to the use of any particular kind of apparatus as
any suitable for the purpose can be utilized, as will be readily understood without
special illustration.
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. The process of producing chlorine by mixing, dry chloride of manganese
with peroxide of iron and heating them in contact with air, as herein before
described.
Second. The production of sesquioxide and peroxide of manganese, by calcining
chloride of manganese with peroxide of iron, as hereinbefore described.
BENCH May of 1000.
J. HENRY JOHNSON,
Agent for the said Thomas Macfarlane.