IMPROVEMENTS IN THE TREATMENT OF ALUNITE OR OF NATURAL PRODUCTS CONTAINING THE SAME, SO AS TO OBTAIN ALUMINOUS COMPOUNDS THERE- FROX
Year: 1875

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the
Office of the Commissioners of Patents, with his Petition, on the
27th May 1875.-A communication from abroad by La Société
Financière de Paris, of Paris, in the Republic of France.
I, JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County
of Middlesex, Gentleman, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE TREATMENT OF ALUNITE OR OF NATURAL
PRODUCTS CONTAINING THE SAME, SO AS TO OBTAIN ALUMINOUS COMPOUNDS THERE-
FROX," a communication to me from abroad by La Société Financière de
Paris, of Paris, in the Republic of France, to be as follows:-
This Invention has for its object a new process for treating alunite or
natural products containing the same, in order to obtain therefrom
potassio alum.
Calcined alunite treated with sulphuric acid, furnishes potassic alum
in quantity corresponding to the sulphate of potassa present, and a
quantity of sulphate of alumina corresponding to the amount of hydrate
of alumina contained in the mineral. In order to obtain the whole of
the alumina in the form of alum it is necessary to add during the

page_text: treatment the proportion of sulphate of potassa corresponding to the
equivalent of the sulphate of alumina present.
The sulphate of potassa of commerce, whatever its origin may be,
costs more than the chlorido of potassium, since it is necessary to
transform the chloride into sulphate, in order to render it available for 5
industrial purposes.
Avoiding the preliminary transformation of the chloride of potassium
into sulphate of potash in the manufacture of alum, effects a saving of
time, labour, and combustible.
Alunite contains about 35 per cent. of sulphuric acid combined with 1
the potassa and with the alumina, that is to say 8.50, combined with
the potassa, and 26.50, combined with the alumina.
If alunite bo submitted to the action of a high temperature the water
of the hydrate of alumina is disengaged in the first place, afterwards the
sulphate of alumina is decomposed into sulphuric acid, sulphurous acid 1
and anhydrous alumina.
In order to transform chloride of potassium into sulphate of potassa,
it is necessary to place the chloride of potassium in contact with
sulphuric acid, and to submit it to the action of licat, so as to transform
the bisulphate, which is produced in the first instance into neutral 2
sulphate.
If a proportion of chloride of potassium equivalent to the quantity of
sulphuric acid, which is disengaged when alunito is submitted to
calcination be calcined with the alunite, the transformation of tho
chloride of potassium into neutral sulphate of potash is effected, and the 2
oxide of iron contained in the alunite is transformed into chloride of iron,
and as chloride of iron is volatilized and thus eliminated from the
calcined mass, which treated after cooling with sulphuric acid suitably
diluted forms potassic alum of the desired purity, and in quantity
corresponding to the amount of potassium contained in the alunite, and 30
to the proportion of chloride of potassium which has been added.