Improvements in the Manufacture of Artificial Cryolite.
Year: 1889

page_text: Date of Application, 18th Apr., 1889
Complete Specification Left, 18th Jan., 1890-Accepted, 15th Feb., 1890
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Artificial Cryolite.
I, MAX NETTO, of 10, Oxford Street Newcastle-on-Tyne, in the county of Northum-
berland, do hereby declare the nature of this invention to be as follows:-
My invention relates to the manufacture of artificial cryolite from the slugs or
scoriae produced in extracting aluminium from the mineral cryolite or from aluminium
fluoride by the action of metallic sodium. These slags consist mainly of sodium.
fluoride with which is intermingled the flux employed in the melting which usually
consists of common salt.
According to my present invention 1 prepare cryolite from the above mentioned
slags, in the following manner, viz. :-I add to the boiling solution of the slag as much
of a heated solution of aluminium sulphate as is necessary in order to convert the
sodium fluoride contained in the slag into sodium sulphate and throw down hydrated
aluminium-fluoride.
After allowing the precipitate to subside I remove the liquid from the hydrated
aluminium fluoride precipitated, and fuse the latter with a suitable quantity of finely
ground slag. The product is cryolite which can be freed from any adhering sodium
sulphate by washing with water, and from any traces of basic aluminium sulphate,
which may adhere to the same by washing with water to which a small quantity of
caustic soda is added.
Dated this 18th day of Annil 1880
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Artificial Cryolite.
I, MAX NETTO, of 10 Oxford Street, Newcastle-on-Tyne, in the County of Northum-
berland, Chemist and Metallurgist 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 :-
My invention relates to the manufacture of artificial cryolite from the slags or
scoriae produced in the process of extracting aluminium from the mineral cryolite
or from aluminium fluoride by the action of metallic sodium. These slags are
composed mainly of sodium fluoride with which is intermingled the flux employed in
the melting, which usually consists of common salt.
According to my present invention, I prepare cryolite from the above mentioned
slags in the following manner, viz. -I first add to a boiling or very bot solution of
the slag, as much of a heated concentrated solution of aluminium sulphate as is
necessary to convert the sodium fluoride contained in the slag into sodium sulphate
and throw down hydrated aluminium fluoride.
After allowing the precipitate to subside, I remove the liquid from the hydrated
aluminium fluoride precipitated, and I mix the latter with a further concentrated
solution of sodium fluoride, or I fuse it with a suitable quantity of finely ground slag
or sodium fluoride.
I find it advantageous, in carrying my invention into practice, to employ the said
materials in or about in the following proportions by weight, that is to say :-I
dissolve thirty two parts of slag containing about forty per cent. of sodium fluoride,
in boiling water or in water having a temperature of about ninety degrees Centigrade.
I also dissolve sixty three parts of hydrated aluminium sulphate at a temperature of

page_text: about sixty degrees Centigrade. I then mix the two solutions, when the sodium
fluoride is decomposed and forms sodium sulphate which remains in solution, while
there is thrown down, as above stated, a precipitate of hydrated aluminium fluoride.
I take say twelve parts of the aluminium fluoride, after the liquid has been removed
therefrom, and treat it with a solution of say twenty five parts of sodium fluoride or
fifty-five parts of slag containing approximately forty per cent. of sodium fluoride.
Or, instead of acting upon the aluminium fluoride with the sodium fluoride in solution,
I mix the said aluminium fluoride with the sodium fluoride or the slag in the dry
state and in, or about in the proportions above stated, and subject the mass to
fusion.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I wish it understood that
I claim -
The manufacture of artificial cryolite from the slags produced by the action of sodium
on natural cryolite or on aluminium fluoride, by adding to a solution of the slag a
solution of aluminium sulphate, and then fusing or mixing the resulting precipitate
with sodium fluoride, substantially as hereinbefore described.
Dated this 18th day of January 1890
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.