Improvements in the Manufacture of Sulphate of Alumina.
Year: 1887

page_text: Date of Application, 25th Feb., 1887
Complete Left, 16th Nov., 1887
Complète Accepted, 16th Dec., 1887
TOIDIONAL DIEUTICALIUN.
Improvements in the Manufacture of Sulphate of Alumina.
We JOHN JAMES HOOD, Analytical Chemist, of 21 Shepherd's Bush Road in the
County of Middlesex, and ALFRED GORDON SALAMON, Analytical Chemist, of
1 Fenchurch Avenue in the City of London, do hereby declare the nature of this
invention to be as follows:-
:-
These improvements relate to the separation of the iron that exists as ferric or
ferrous salts in crude aluminic sulphate. To effect this separation, the ferrous salt is
oxidised to the ferric state, and the aluminous solution rendered somewhat basic.-To
the solution thus prepared, a solution of a soluble tungstate (by preference the material
known in commerce as sodic tungstate) is gradually added, which at first produces a
bulky white precipitate. On vigorously agitating the aluminous solution, this
precipitate dissolves, and after a short time a yellow precipitate comes down, consisting
of a compound of tungstic oxide and ferric oxide, which may be filtered off or
separated by decantation, leaving the sulphate of alumina in a comparatively pure
state.
When employing tungstate of soda as the tungstic salt for precipitating, we find
that about seven tenths by weight are necessary to precipitate one tenth by weight of
ferric oxide, being a little in excess of that required (63), theoretically, for forming
ferric tungstate with the above amount of ferric oxide.
For recovery of the precipitate; it is washed to freo it from aluminic sulphate, and
boiled with sodic hydrate or carbonate, by preference the former, separated from the
precipitated ferric hydrate, and the solution of soluble tungstate is again ready for
acting upon more ferriferous aluminic sulphate.
NEWTON & SON,
Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Sulphate of Alumina.
We JOHN JAMES HOOD, Analytical Chemist of 21 Shepherd's Bush Road in the
County of Middlesex, and ALFRED GORDON SALAMON, Analytical Chemist, of
1 Fenchurch Avenue in the City of London 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 :—
These improvements relate to the separation of the iron that exists as ferric or
ferrous salts in crude aluminic sulphate.-To effect this separation, the ferrous salt is
first oxidised to bring it to the ferric state, the aluminous solution being rendered
somewhat basic. To this end, we preferably employ potassic chlorate, the
amount being proportioned to the iron salt to be oxidised, namely, 122 parts by weight
for every 432 parts by weight of ferrous oxide present in the sulphate of alumina. To
the solution thus prepared, a solution of a soluble tungstate (by preference the material
known in commerce as sodic tungstate) is gradually added, which at first produces a
bulky white precipitate. On vigorously agitating the aluminous solution, this
precipitate dissolves, and after a short time, a yellow precipitate comes down, con-
sisting of a compound of tungstic oxide and ferric oxide, which may be filtered off or
separated by decantation, leaving the sulphate of alumina in a comparatively pure
state.
When employing tungstate of soda as the tungstic salt for precipitating, we find
that about seven tenths by weight are necessary to precipitate one tenth by weight of
ferric oxide, being a little in excess of that required (63) theoretically, for forming
ferric tungstate with the above amount of ferric oxide.
For recovery of the precipitate, it is washed to free it from aluminic sulphate, and
boiled with sodic hydrate or carbonate, by preference the former, separated from the
precipitated ferric hydrate, and the solution of soluble tungstate is again ready for
acting upon more ferriferous aluminic sulphate.--Practically, it is immaterial what
strength of sodic hydrate or carbonate is employed for decomposition of the precipitate;
a solution of about 20% to 30% we find useful.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what we
claim is :-
1. The process herein described for freeing sulphate of alumina from its ferric
compounds.
2. In the manufacture of sulphate of alumina, the conversion of the ferrous salts
contained therein to the ferric state, as and for the purpose above set forth.
Dated this 16th day of November 1887
NEWTON & SON,
Agents for the Applicants.