Double Fluoride of Aluminium and an Alkali.
Year: 1886

page_text: Date of Application, 25th Oct.. 1886
Complete Left, 23rd July, 1887
Complete Accepted, 25th Oct., 1887
Double Fluoride of Aluminium and an Alkali.
I, LUDWIG GRABAU of 15ª Höltystrasse, Hanover, Germany, Civil Engineer, do
hereby declare the nature of this invention to be as follows:-
1
The present invention relates to the preparation of fluoride of aluminium and the
double fluoride of aluminium and an alkali, by the action of suitable quantities of the
fluoride of an alkali upon a peculiar solution prepared from sulphate of alumina or
alum, and the subsequent evaporation or heating and lixiviation of the mass
obtained.
The said solution is obtained by treating a solution of sulphate of alumina or of
alum with pulverized fluor-spar, preferably in the heated state. The greater part of
the sulphuric acid combined with the alumina (from to according to circum-
stances,) is thereby replaced by fluorine, gypsum being simultaneously formed. The
remainder of the sulphuric acid, not replaced by fluorine, is, however, by no means
contained in the solution as sulphate of alumina mixed with the aluminium fluoride,
which is soluble in water, as is shown by the fact that from the solution, even in a
concentrated state, no alum can be obtained by sulphate of ammonia or sulphate of
potash. The remaining sulphuric acid is, rather, chemically combined with the
aluminium fluoride, so that the solution can be designated an aluminium fluorine
sulphate solution.
The treatment of this solution to obtain aluminium fluoride or a double fluoride of
aluminium and an alkali takes place in the following manner.
a. PREPARATION OF ALUMINIUM FLUORIDE.
For this purpose, I inix with the aluminium fluorine sulphate solution as much
fluoride of an alkali as is equivalent to the sulphuric acid combined with the alumina
and lime. This mixture is then evaporated and heated, and lixiviated with water until
the residue is free from sulphuric acid. This product is the richest in aluminium
fluoride that can be obtained in the treatment of the aluminium fluorine sulphate
solution.
Dan
AT TEMEINTIERE AND SODUMOR POTASSIUM

page_text: solution as much fluoride of sodium or potassium as is necessary for converting all the
aluminium into the double fluoride and the small quantity of dissolved gypsum into
calcium fluoride.
The precipitate is separated in a suitable manner from the bye-products of the
reaction, and either the whole mixture of aluminium fluorine sulphate and fluoride
of sodium or potassium or only the previously decanted precipitate is suitably
evaporated to dryness. The precipitate thereby becomes denser and can be more
easily washed out.
The heating of the evaporated mixture is useless in the preparation of the ordinary
double fluoride. If however double fluorides are to be obtained which contain for one
molecule Al, F1 6 less than six molecules Na Fl or K Fl the evaporation to dryness,
as well as subsequent heating or melting of the mass before the lixiviation, is
indispensable.
Dated thin 95th day of Antohan 1006
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London,
Agents for the Applicant.

page_text: Double Fluoride of Aluminium and an Alkali.
I, LUDWIG GRABAU of 41 Schiffgraben, Hanover, in the Empire of Germany,
Civil Engineer 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 :-
The present invention relates to the preparation of fluoride of aluminium and the
double fluorides of aluminium and an alkali by the action of suitable quantities of the
fluoride of an alkali upon a peculiar solution prepared from sulphate of alumina or
alum, and the subsequent evaporation or heating and lixiviation of the mass
obtained.
The said peculiar solution is obtained by treating a solution of sulphate of alumina
or of alum with pulverized fluorspar, preferably in the heated state. The greater part
of the sulphuric acid combined with the alumina (from to according to circum-
stances) is thereby replaced by fluorine, gypsum being simultaneously formed. The
remainder of the sulphuric acid, not replaced by fluorine, is however, by no means,
contained in the solution as sulphate of alumina mixed with the aluminium fluoride,
which is soluble in water, as is shown by the fact that from the solution, even in a
concentrated state, no alam can be obtained by sulphate of ammonia or sulphate of
potash. The remaining sulphuric acid is rather chemically combined with the
aluminium fluoride so that the solution can be designated an aluminium fluorine
sulphate solution.
The process forming the subject of the present invention is carried out in the
following manner.
A. PREPARATION OF ALUMINIUM FLUORIDE.
1. This solution is mixed with as much fluoride of an alkali as is equivalent to
the sulphuric acid combined with the alumina and line. This mixture is then
evaporated and heated, and lixiviated with water until the residue is free from
sulphuric acid. This product is the richest in aluminium fluoride that can be obtained
in the treatment of the aluminium fluorine sulphate solution.
B. PREPARATION OF DOUBLE FLUORIDE OF ALUMINIUM AND SODIUM OR POTASSIUM.
To prepare the said double fluorides I mix with the aluminium fluorine sulphate
solution as much fluoride of sodium or potassium as is necessary for converting all
the aluminium into the double fluoride, and the small quantity of dissolved gypsum
into calcium of fluoride.
The precipitate is separated in a suitable manner from the by-products of the
reaction and either the whole mixture of aluminium fluorine sulphate and fluoride of
solim or potassium or only the previously decanted precipitate is suitably evaporated
to dryness. The precipitate thereby becomes denser and can be more easily washed out.

page_text: The beating of the evaporated mixture is useless in the preparation of the ordinary
double fluoride. If however double fluorides are to be obtained which contain for one
molecule Al, Fl, less than six molecules Na Fl or K Fl the evaporation to dryness as
well as subsequent heating or melting of the mass before the lixiviation is
indispensable.
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 preparation of aluminium fluoride and alkaline double fluorides thereof
by mixing a solution of aluminium fluorine sulphate with (according to the product to
be obtained) different quantities of alkaline fluoride and subsequent evaporation, or
heating or melting and lixiviation.