IMPROVEMENTS IN THE PURIFICATION OF ALKALINE SOLUTIONS, AND IN THE PRODUCTION OF AMMONIA
Year: 1880

page_text: LETTERS PATENT to Eustace Carey, Holbrook Gaskell, the younger, and
Ferdinand Hurter, Ph. D., all of Widnes, in the County of Lancaster, Chemical
Manufacturers, for an Invention of "IMPROVEMENTS IN THE PURIFICATION OF
ALKALINE SOLUTIONS, AND IN THE PRODUCTION OF AMMONIA,"
PROVISIONAL SPECIFICATION left by the said Eustace Carey, Holbrook
Gaskell, and Ferdinand Hurter at the Office of the Commissioners of Patents
on the 11th February 1880.
EUSTACE CAREY, HOLBROOK GASKELL, the younger, and FERDINAND HURTER,
Ph. D., all of Widnes, in the County of Lancaster, Chemical Manufacturers.
"IMPROVEMENTS IN THE PURIFICATION OF ALKALINE SOLUTIONS, AND IN THE
PRODUCTION OF AMMONIA."
Our Invention relates to improvements in the process for the purification of
alkalino solutions, in respect of which Letters Patent were granted to us bearing
date the 18th July 1879, No. 2939.
According to our present Invention we purify alkaline solutions containing
ferrocyanides and monosulphides by treating them with carbonic acid and an
oxygen compound, and afterwards heating them to about 350° F., or such other
temperature as will cause the oxygen compound to part with some or all of its
oxygen.
Such oxygen compounds, for example, are manganese dioxide, and nitrate of
soda or potash.
When using manganese we may afterwards recover it by means of atmospheric
oxygen, or we may use it in conjunction and simultaneously with such oxygen.
During the aforesaid treatment of the solutions ammonia is formed and may be
collected and utilized.
In some cases the carbonic acid is first added to the solutions, and they are then
placed in the furnace and the oxygen compound is introduced, the oxygenation and
heating being thus performed simultaneously.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Eustace Carey, Holbrook Gaskell, and Ferdinand Hurter in the Great
Seal Patent Office on the 6th August 1880.
EUSTACE CAREY, HOLBROOK GASKELL, the younger, and FERDINAND HURTER,
Ph. D., all of Widnes, in the County of Lancaster, Alkali Manufacturers.
"IMPROVEMENTS IN THE PURIFICATION OF ALKALINE SOLUTIONS, AND IN THE
PRODUCTION OF AMMONIA."
Our said Invention relates to improvements in the process for the purification of
alkaline solutions, in respect of which Letters Patent were granted to us bearing
date the 18th July 1879, No. 2939, and it consists in subjecting such alkaline
solutions to the nction of carbonic acid, and of certain sulphur compounds produced
in the said alkaline solutions by the addition of manganese oxide, sodium nitrate,
or other suitable oxygen compounds, in order that the silica, alumina, and iron
contained in the said solutions inay be separated therefrom.
Our said Invention also relates to the production of ammonia by or during such
improved process of treating alkaline solutions.
In carrying out our said Invention we proceed in the following manner, vist. :-
We first subject the alkaline solutions containing ferrocyanides and sulphur
compounds, as well as other impurities, to the action of carbonic acid (which inay
or may not be mixed with atmospheric air), whereby we remove as far as possible
the silica and alumina usually found in those solutions, and thus prevent or greatly
diminish the incrustation or deposit in the boiler in which the solutions are to bo
subsequently treated, as hereinafter described.
To the solutions so carbonated and freed as far as possible from silica and
alumina we add an oxydising agent consisting of an oxygen compound, such, for
example, as peroxide of manganese or nitrate of soda, or any other oxide capable of
converting the sodium monosulphide into sodiuin thiosulphate (hyposulphite),
either at the ordinary temperature or at a higher one, not exceeding however the
temperature to which the solutions have to be afterwards subjected.
When using manganese as an oxydising agent, and operating in the manner
herein before described, we add the manganese in sufficient quantity to produce at
once the required amount of thiosulphate (hyposulphite), or wo inay add the
manganese (in insuflicient quantity) before the solution is carbonated, and then
subject the solution to the action of carbonic acid, which in this case is mixed with
a sufficient quantity of oxigen to produce a further quantity of thiosulphate, the
manganese acting then simply as a carrier of oxygen to the monosulphide.
In either case wo settle or filter the solution, and may recover the manganese and
use it for a further operation.
When using sodium nitrate we add it to the filtered or settled carbonated solution
in sufficient quantity to yield the necessary amount of thiosulphate.
On the solutions being subjected to an olevated temperature, as hereinafter
described, the following reaction occurs between the sodium nitrate and the sodium
monosulphide
2 Na, S+ Na NO, + 2 H₂O
=
Na O Na HO + Na, S. O, + NH„
2 Na, S + Na NO, + 2 H₂O =
Na O Na HO + Na, S. O, + NH..
Thus we have to employ for every equivalent of thiosulphate which we wish to
produce at least one equivalent of sodium nitrate.
In whatever way however the sodium thiosulphate be produced thero must be
so much thereof as is sufficient to decompose the whole of the ferrocyanide present
in the solution.
We find that for this purpose at least from five to six equivalents of thiosulphate
are necessary to decompose one equivalent of ferrocyanide, or for every part of

page_text: anhydrous ferrocyanide by weight which the solution contains there must be present
from 2.6 to 3.2 parts by weight of anhydrous thiosulphate, as most of the ferro-
cyanide splits up according to the following equation :—
Na Fe Cy+G N₁₂ S, O₂ + N₁₂ O =
6 Na Cy S6 Na, SO, + Fe O.
Having thus prepared the solutions we subject them afterwards to the action of
heat in a boiler, preferably a tubular one. The boiler described in the Specification
to our said former Letters Patent is suitable for this purpose.
The temperature necessary for this decomposition is at least 350° F. If this
temperature is not attained or surpassed no decomposition will take place. It is
clear that in order to prevent evaporation of the solutions before they attain this
temperature they should be kept under suitable pressure. We obtain this pressuro
by forcing the liquid against a loaded valve which opens only when tho liquid is
under a pressure of from 200 to 300 lbs. per square inch.
The solution, when leaving this boiler, may then be freed from the iron which
has been precipitated by filtering or settling, and is ready for use in the manu-
facture of refined alkali, soda crystals, or any other form of soda in which freedom
from silica, alumina, and iron is desirable.
During the heating of these solutions, particularly when nitrate of soda is used,
ammonia is evolved.
The ammonia, which arises partly from the decomposition of the sodium ferro-
cyanide and partly from the decomposition of the sodium nitrate, may be recovered
by any well known method.
Having now described and particularly ascertained the nature of our said Inven-
tion, and the manner in which the same is or may be used or carried into effect, we
would observe in conclusion that what we consider to be novel and original, and
therefore claim as the Invention secured to us by the hereinbefore in part recited
Letters Patent is,-
Firstly. The system or mode of purifying alkaline solutions by submitting the
same to the action of carbonic acid and of certain sulphur compounds produced in
such alkaline solutions by the addition thereto of manganese oxide, sodium nitrate,
or other suitable oxygen compounds, in order that the silica, alumina, and iron
contained in the said solutions may be separated therefrom, substantially as
herein before described.
Secondly. The production of ammonia by or during the treatment of the said
solutions, substantially as herein before described.
In witness whereof, we, the said Eustace Carey, Holbrook Gaskell, the younger,
and Ferdinand Hurter, have to this our Specification set our hands and seals,
the Twenty third day of July, One thousand eight hundred and eighty.