as Tank or Vat Liquors.
Year: 1885

page_text: as Tank or Vat Liquors.
I JAMES FREDERICK CHANCE of the firm of Chance Brothers of Oldbury in the
county of Worcester, Alkali Manufacturer do hereby declare the nature of the said
invention for IMPROVEMENTS IN THE PURIFICATION OF THE ALKALINE LEES KNOWN
AS TANK OR VAT LIQUORS to be as follows:-
=
This invention has for its object the purification of alkaline lees.
In the manufacture of soda and potash by the Le Blanc process, the crude alkaline
lees known in the trade as tank or vat liquors are invariably contaminated with
sulphides of the base, which are very troublesome to deal with.
In order to remove these sulphides readily and cheaply I treat the lees with a
mixture of oxides or carbonates of iron and lime or carbonate of lime in such pro-
portion that there shall always be present iron in excess of the equivalent required
to convert the sulphides of sodium or potassium into sulphide of iron.
There may be used in the mixture natural or artificially prepared hydrated or
anhydrous oxides or carbonates of iron or a mixture of any of these but I prefer to
use such a mixture as is obtained by precipitating a solution of chloride or chlorides
of iron with a considerable excess of lime or carbonate of lime. Should the final
product of manufacture be caustic soda or potash I prefer to use caustic lime in the
mixture, and as the precipitant but should it be desired to make carbonate of Soda
or Potash from the lees, then I prefer to use a finely divided carbonate of lime such
for instance as the precipitated carbonate of lime produced as a bye product in the
manufacture of caustic soda and known in the trade as Caustic Lime Mud.
The mixture is introduced into a vessel where it is subjected to violent agitation
so that it is brought into intimate contact with the liquor, and the sulphide of
sodium or potassium is readily converted into oxide or carbonate of the base, the
sulphur entering into combination with the iron and forming an insoluble sulphide
of iron which is separated from the lees by filtration or otherwise.
.
The purified lees are then treated by the ordinary methods for the manufacture
of caustic soda or potash or their carbonates. The vessel I prefer has the form of
a closed horizontal cylinder along whose axis runs a shaft fitted with agitating
knives and capable of rapid revolution so as to thoroughly agitate and mix the
above described mixture with the alkaline lees.

page_text: as Tank or Vat Liquors.
I JAMES FREDERICK CHANCE of the firm of Chance Brothers of Oldbury in the
County of Worcester Alkali Manufacturer, 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 has for its object the purification of alkaline lees.
In the manufacture of soda and potash by the Le Blanc process the crude alkaline
lees known in the trade as tank or vat liquors are invariably contaminated with
sulphides of the base, which are very troublesome to deal with.
In order to remove these sulphides readily and cheaply I treat the lees with a
mixture of oxides or carbonates of iron and lime or carbonate of lime in such pro-
portion that there shall always be present iron in excess of the equivalent required
to convert the sulphides of sodium or potassium into sulphide of iron.
There may be used in the mixture natural or artificially prepared hydrated or
anhydrous oxides or carbonates of iron or a mixture of any of these, but I prefer
to use such a mixture as is obtained by precipitating a solution of chloride or
chlorides of iron with a considerable excess of lime, or with a mixture containing a
sufficient quantity of lime to decompose the chloride or chlorides of iron and an
excess of carbonate of lime.
For the carbonate of lime I may conveniently use the precipitated carbonate of
lime produced as a bye-product in the manufacture of caustic soda and known in
the trade as caustic lime mud,
The mixture is introduced into a vessel, where it is subjected to violent agitation,
so that it is brought into intimate contact with the liquor, and the sulphide of sodium
or potassium is readily converted into oxide or carbonate of the base, the sulphur
entering into combination with the iron and forming an insoluble sulphide of iron,
which is separated from the lees by filtration or otherwise. The purified lees are
then treated by the ordinary methods for the manufacture of caustic soda or potash
or their carbonates. The vessel I prefer has the form of a closed horizontal cylinder
along whose axis runs a shaft fitted with agitating knives and capable of rapid
revolution, so as to thoroughly agitate and mix the above described mixture with
the alkaline lees.
I am
aware that iron has been proposed by other patentees for removing
sulphides from vat liquors, I do not therefore claim the employment of iron

page_text: Having now particularly described and ascertained the nature of the said
invention, and in what manner the same is to be performed I declare that what
I claim is:
First. The purification of alkaline lees by means of a mixture of oxides or
carbonates of iron with caustic lime or carbonate of lime substantially as herein
Betforth.
Second. Agitating alkaline lees with the admixture of the substances herein.
before specified for the purpose setforth.