IMPROVE- MENTS IN THE PURIFICATION OF ALKALINE SOLUTIONS
Year: 1881

page_text: LETTERS PATENT to Henry Wade Deacon and Holbrook Gaskell, the younger,
both of Widnes, in the County of Lancaster, for an Invention of "IMPROVE-
MENTS IN THE PURIFICATION OF ALKALINE SOLUTIONS."
PROVISIONAL SPECIFICATION left by the said Henry Wade Deacon and
Holbrook Gaskell at the Office of the Commissioners of Patents on the
5th December 1881.
HENRY WADE DEACON and HOLBROOK GASKELL, the younger, both of Widnes,
in the County of Lancaster. 'IMPROVEMENTS IN THE PURIFICATION OF ALKALINE
SOLUTIONS."
"
This Invention relates to the more complete separation of iron from the alkaline
solutions, for the purification of which Letters Patent were granted to Eustace
Carey, Holbrook Gaskell, junior, and Ferdinand Hurter, dated July 18th, 1879,
No. 2939, February 11th, 1880, No. 608, March 17, 1881, No. 1161.
Under those Patents the alkaline solutions are first purified from silica and
alumina by passing carbonic acid through the solutions, and removing the
precipitated silica and alumius by filtration or settling.
The alkaline solutions are then heated under pressure in a coil or boiler until the
ferrocyanide contained in the liquors is decomposed, and the iron existing in the
ferrocyanide is transformed into an insoluble compound and becomes suspended
in the liquor as sulphide of iron, to be afterwards removed by settling, filtration, or
otherwise.
The sulphide of iron thus formed is precipitated in an extremely fine state of
division, and it is difficult to remove it completely by filtration and its entire
separation by settling occupies a very considerable time.
After the alkaline solutions have been treated with carbonic acid for the
separation of silica and alumina they usually contain free carbonic acid, or bicar-
bonate, or sesquicarbonate of soda, or in other words, contain carbonic acid in
excess of the quantity necessary to form monocarbonate of soda.
During the subsequent treatment of the alkaline solution in the coil, or boiler, or

page_text: apparatus, this excess of carbonic acid causes the iron to remain in or pass into
solution, thereby injuriously affecting the quality of such solution.
Now our Invention consists in removing or neutrilizing such excess of carbonic
acid by adding to or producing in the said solution sufficient caustic soda for the
purpose, and in more rapidly separating the sulphide of iron which is held in
suspension in the liquor after the ferrocyanide has been decomposed in the coil or
boiler by agitating and cooling the liquor by causing atmospheric air to pass into
or through it.
In carrying out our said Invention we prefer to treat the alkaline solution after
the precipitated silica and alumina havo been removed from the said solution by
filtration or otherwise, and we do this either by adding to the solution hydrate of
lime in sufficient quantity to remove or neutralize the whole of the excess of
carbonic acid, in which case the carbonate of lime produced must be removed by
filtration, or separation and subsequent decantation, or by other effective methods
before the liquor is treated in the coil or boiler referred to in the previously
mentioned Patents.
Or we add to the solution, from which the silica and alumina have been
removed, caustic soda, either solid or preferably in solution, until all excess of
carbonic acid is neutralized, that is to say, until a proto or mono carbonate has been
produced.
Whichever method be adopted we prefer (to ensure the complete neutralization
of the excess of carbonic acid to render the alkaline solutions slightly caustic
before they are caused to pass into or through the before mentioned coil or
.boiler.
The solution thus treated and prepared is next subjected to an elevated tempe-
rature in a coil or boiler, as is well understood, the same being employed for the
purpose of effecting the decomposition of the ferrocyanide. The insoluble
compounds of iron thus produced are suspended in the liquor as sulphide of iron.
We next effect the separation of the suspended sulphide of iron from the solution
with extreme rapidity and ease by agitating and cooling the liquor containing.the
sulphide of iron in suspension by passing a current or currents of atmospheric air
into or through the solution contained in a settler or other convenient vessel (the
shape of which is unimportant) and which may be constructed of iron or other
suitable material.
The solution is then freed from the precipitate thus produced and obtained either
by settling, filtration, or other effective method, and it is then ready for evaporation
or for crystallization.
We prefer to cause the air to pass through the solution either by propulsion
or exhaustion, and by means of any of the well known appliances for the purpose.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Henry Wade Deacon and Holbrook Gaskell in the Great Seal
Patent Office on the 3rd June 1882.
HENRY WADE DEACON and HOLBROOK GASKELL, the younger, both of Widnes
in the County of Lancaster. "IMPROVEMENTS IN THE PURIFICATION OF ALKALINE
SOLUTIONS."
This Invention relates to the more complete separation of iron from the alkaline
solutions for the purification of which Letters Patent were granted to Eustace
Carey, Holbrook Gaskell, junior, and Ferdinand Hurter, dated July Eighteenth,
One thousand eight hundred and seventy nine, No. 2939; February Eleventh, Ono
thousand eight hundred and eighty, No. 608; March Seventeenth, One thousand
eight hundred and eighty one, No. 1161.
Under those Patents the alkaline solutions are first purified from silica and
alumina by passing carbonic acid through the solutions, and removing the
precipitated silica and alumina by filtration or settling.
The alkaline solutions are then heated under pressure in a coil or boiler until
the ferrocyanide contained in the liquors is decomposed, and the iron existing in
the ferrocyanide is transformed into an insoluble compound and becomes suspended
in the liquor as sulphide or oxide of iron; to be afterwards removed by settling,
filtration, or otherwise. The sulphide or oxide of iron thus formed is precipitated
in an extremely fine state of division, and it is difficult to remove it completely
by filtration, and its entire separation by settling occupies a very considerable
time.
After the alkaline solutions have been treated with carbonic acid for the
separation of silica and alumina, they usually contain free carbonic acid, or bicar-
bonate or sesquicarbonate of soda, or in other words, contain carbonic acid in
excess of the quantity necessary to form monocarbonate of soda.
During the subsequent treatment of the alkaline solution in the coil, or boiler,
or apparatus, this excess of carbonic acid causes the iron to remain in or pass into
solution, thereby injuriously affecting the quality of such solution.
Now our Invention consists in removing or neutralizing such excess of carbonic
acid by adding to or producing in the said solution sufficient caustic soda for the
purpose, and in more rapidly separating the sulphide or oxide of iron which is held
in suspension in the liquor after the ferrocyanide has been decomposed in tho
coil or boiler by agitating and cooling the liquor by causing atmospheric air to pass
into or through it.
In carrying out our said Invention we prefer to treat the alkaline solution after
the precipitated silica and alumina have been removed from the said solution by
filtration or otherwise, and we do this either by adding to the solution hydrate of
lime in sufficient quantity to remove or neutralize the whole of the excess of
carbonic acid, in which case the carbonate of lime produced must be removed by
filtration, or separation and subsequent decantation, or by other effective methods,
before the liquor is treated in the coil or boiler referred to in the previously
mentioned Patents,
Or we add to the solution, from which the silica and alumina have been
removed, caustic soda, either solid or preferably in solution, until all excess of
carbonic acid is neutralized, that is to say, until a proto or mono carbonate has
been produced.
Whichever method be adopted, we prefer to ensure the complete neutralization
of the excess of carbonic acid, so as to render the alkaline solutions slightly
•

page_text: caustic before they are caused to pass into or through the before mentioned coil
or boiler.
The solution thus treated and prepared is next subjected to an elevated tempe-
rature in a coil or boiler, as is well understood, the same being employed for the
purpose of effecting the decomposition of the ferrocyanide. The insoluble
compounds of iron thus produced are suspended in the liquor, as sulphide or oxide
of iron.
We next effect the separation of the suspended sulphide of iron from the solution
with extra rapidity and ease by agitating and cooling the liquor containing the
sulphide of iron in suspension, by passing a current or currents of atmospheric air
into or through the solution contained in a settler or other convenient vessel (the
shape of which is unimportant), and which may be constructed of iron or other
suitable material.
'
The solution is then freed from the precipitate thus produced and obtained
either by settling, filtration, or other effective method, and it is then ready for
evaporation or for crystallization.
We prefer to cause the air to pass through the solution either by propulsion or
exhaustion, and by means of any of the well known appliances for the purpose.
Having now described and particularly ascertained the nature of our said
Invention, and the method of carrying it into effect, we would observe in
conclusion that what we consider to be novel and original, and therefore cluim as
the Invention secured to us by the herein before in part recited Letters Patent is,-
First. The production in or the addition to the alkaline solutions herein-before
mentioned of caustic soda, substantially for the purpose and in the manner herein-
before described.
Second. Effecting the more rapid separation of the insoluble compounds of iron
from the said alkaline solutions by causing air to pass through the solutions,
substantially as herein before described.
In witness whereof, we, the said Henry Wade Deacon and Holbrook Gaskell,
the younger, have to this our Specification hereunto set our hands and
seals, the Second day of June, One thousand eight hundred and eighty
two.
HENRY WADE DEACON.
(L.S.)
HOLBROOK GASKELL, JR. (L.S.)