IMPROVEMENTS IN MANUFACTURING CARBONATE OP SODA
Year: 1870

page_text: PROVISIONAL SPECIFICATION left by Patrick Cockburn. Don at the
Office of the Commissioners of Patents, with his Petition, on the
27th July 1870. A communication from abroad by Emil Bergmann, ♬
of Wetzlar, Prussia.
I, PATRICK COCKBURN DON, of No. 39, Lime Street, in the City of
London, Merchant, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN MANUFACTURING CARBONATE OP SODA," (a com-
munication), to be as follows:-
The objects of my Invention are to recover the sulphur used, and to
re-employ such recovered sulphur in the form of sulphurous acid, and,
finally in that of sulphuric acid in the process of manufacturing,
carbonate of soda, and to obtain an economical supply of carbonic acid.
gas to be used in this and in other operations.
Under the present method of manufacturing carbonate of soda the
sulphur employed therein is generally a waste product. By my method
the sulphur is regained, partially or wholly, and is re-applied to the same;
purpose.

page_text: .
Under the existing system of manufacturing carbonate of soda, lime
or carbonate of lime mixed with coal is the agent used to abstract the
sulphur from the sulphate of soda or salt cake employed therein. But
no satisfactory or sufficiently economical method has yet been devised by
which the sulphur so abstracted can be regained and re-applied in the
said manufacture. It has been proposed, with a view to such recovery
and re-application, to substitute for the oxide of calcium or for carbonate
of lime one or other of the oxides of iron or of manganese, but because
of the imperfect character (to be herein-after more particularly referred
to) of the operations hitherto suggested in these cases, such substitutions
have not proved successful as manufacturing operations.
"
Now my Invention consists in the application of carbonic acid gas in
manner as herein-after described in the operation of lixiviating the
"black balls or crude soda when either the oxides of iron or oxides of
manganese have been used as the agents for abstracting the sulphur
from the sulphate of soda, or in that operation which is known as the
"black ball” process in the manufacture of carbonate of soda. It is
well known that the carbonate of manganese and the oxides of iron, as
well as certain other metallic oxides, have been proposed to be sub-
stituted for lime or carbonate of lime in the said "black ball" operation
in manufacturing carbonate of soda, such substitution having for its
final object, as already said, the recovery of the sulphur from the
sulphuret of manganese or the sulphuret of iron or sulphurets of certain
other metals obtained under such proposed application. But in the
working of these methods certain practical difficulties have hitherto
intervened, arising from the fact that the carbonate of soda obtained by
lixiviation of the black ball is (under any method yet proposed) left
contaminated with certain compounds of manganese when manganese is
the agent, or of iron when iron is the agent employed. Now my
Invention consists in obviating this defect in the older operations by one
or other of the following methods, wherein preferably I employ one or
other of the oxides of manganese, and under this application I proceed
as follows, namely, to 72 lbs. of sulphate of soda or salt cake I add
38 lbs. of oxide or mixture of oxides of manganese recovered by the
process herein-after mentioned, or obtained from any other source, or
oxides of iron, & 10 lbs. of small coal or coal slack. I do not confine
my operations to these proportions exactly, for they may be varied in.
their relative proportions according to circumstances, but such pro-

page_text: portions I find to be practically useful. These mixed together as usual
in soda manufacturing operations are thrown into the reverbatory
furnace and worked after the customary manner of making the ordinary
"black ball" of soda makers. When furnaced or finished the black ball
or mixture, as above described, is withdrawn from the furnace and
cooled, as usual, then broken up and thrown into the lixiviating vat and
water added. Through the said materials contained in the vats used to
lixiviate the manganesed "black ball" I then cause to pass in the act of
lixiviation a current of carbonic acid gas, obtained from any source, but
obtained preferably in manner as follows, namely, I cause atmospheric air
to be passed through or into ignited coke, or coal, or charcoal contained
in any convenient or well-known apparatus used for that purpose, or in
any apparatus or furnace to be specially constructed for that purpose,
whereby is produced a mixture of carbonic acid gas and nitrogen gas.
This gaseous mixture I cause to be pumped into or drawn through or
by any other contrivance brought in contact with the liquor contained
in the lixiviating vat. The effect of this application of carbonic acid gás
is to carbonize the soda and to completely separate all manganese oxide
or other manganese compounds from the solution of the carbonate of
soda. The insoluble residue so obtained consists chiefly of sulphuret of
manganese. The sulphuret of manganese or residue obtained as above
after being dried is then burnt either in the usual manner of burning
other sulphurets for the manufacture of sulphurous acid, and finally on
sulphuric acid, or in any other convenient manner. The residue of such
burning (consisting chiefly of oxide or a mixture of oxides of manganese
when manganese is the base employed) is then re-applied in the treat-
ment of sulphate of soda for the manufacture of "black ball," as above
described. The same general method of working is equally applicable
when the oxides of iron are used.
In my operation for procuring the carbonic acid gas I preferably
cause atmospheric air to be forced into or drawn through a long column
of coke, or coal, or charcoal, and I take the gaseous products of such an
action from the lower or under end of such column, whereby I secure
carbonic acid gas unmixed with carbonic oxide.
I sometimes vary the method described as above when desirable in
manner as follows, namely:-I cause the carbonic acid gas or the
mixture of that gas and nitrogen gas obtained as before mentioned to be
cooled, and in that state to be passed into a solution of carbonate of

page_text: soda, thereby forming a solution of the sesquicarbonate, or, as commonly
called, the bicarbonate of soda. This solution I add to the water
contained in the lixiviating vat herein-before described, and in this way
obtain, as before, a pure or comparatively pure solution of carbonate of
soda, and effect at the same time a complete separation of the manganese
or iron from the soda solution in the form (chiefly) of sulphuret, as
herein before stated...
I do not claim as my Invention the application of oxide or mixture of
oxides either of iron or of manganese in the manufacture of carbonate
of soda or as substitutes of lime in that operation, because such
applications have already been proposed; but what I do claim as my
Invention is, the application of carbonic acid gas howsoever obtained by
passing it or mixtures containing it into or through the liquor contained
in the lixiviating vat and in the act of lixiviation when the black ball or
crude soda has been obtained through the agency of either oxides of
manganese or of iron, as herein-before described.
I also claim as my Invention the use of a solution of sesquicarbonate
(or bicarbonate) of soda for effecting the separation of manganese or
iron compounds from the carbonate of soda, as herein-before described.
I also claim as my Invention the improved method of procuring
carbonic acid gas as herein-before described.