Improvements in Processes for the Manufacture of Aluminium Compounds.
Year: 1893

page_text: Date of Application, 12th Sept., 1898-Accepted, 14th Oct., 1893
COMPLETE SPECIFICATION.
Improvements in Processes for the Manufacture of Aluminium
Compounds.
I, WILLARD ERASTUS CASE, of 196 West Genesee Street, Auburn, New
York, United States of America, Counsellor at Law, do hereby declare the nature
of my invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement::--
The object of my invention is to produce an aluminium compound which from
its constitution and physical properties is capable of many uses in the arts.
Another and further object of my invention is to obtain this product free from
iron, even though the crude materials from which it is produced may have contained
iron as an impurity.
My process is as follows in case iron is present in the materials used.:
Supposing a sample of aluminium sulphate to be used which contains iron in
both the ferrous and ferric forms, as an impurity, I dissolve this sulphate in water,
preferably heating this solution to 180 degrees Fahrenheit to expedite the
subsequent reaction, and having previously ascertained the quantity of iron
present in ferrous condition, add a suitable quantity of nitric and sulphuric
acids to oxydise this ferrous iron to the ferric condition, in accordance with the
well known formula which represents said reaction, and I prefer to add said acids
in slightly greater quantities than is indicated by the requirements of said
reaction.
I now add a quantity of calcium fluoride, preferring, on account of its cheapness,
commercial ground fluor-spar.
The temperature of the solution now being preferably maintained for several
I next separate, by filtration or otherwise, the precipitated calcium sulphate,
(together with such excess of calcium fluoride as remains undecomposed), from the
resulting fluor-sulphate solution.
For the next step I consider it advisable, although not essential, that this
solution should bave a specific gravity of about 1:040.
I next prepare an aqueous solution of an alkali carbonate or hydrate, for
example sodium carbonate or ammonium hydrate, which solution I prefer to have
concentrated, and which I call my "alkali solution."
1 now add some of the alkali solution to the fluor-sulphate solution, (which causes
a reddish ferruginous precipitate), until upon removing, filtering and testing a small
sample of this solution,with potassium ferrocyanide, it shows itself to be substan-
tially free from iron in the ferric form; and then by filtration or otherwise, I
remiove the said iron precipitate.
T
More of the alkali solution is now added to the fluor-sulphate solution until it
ceases to bring down a further quantity of a white precipitate, and this white
precipitate I prefer to remove at once from said solution by filtration or otherwise.
This product is rich in aluminium and free from such iron as may have been
present in the original aluminium sulphate.
It is of particular value as a source of aluminium to be extracted by electrolysis
or otherwise, and its physical properties render it useful for other purposes.

page_text: Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is:
1. The process of producing an aluminium fluor-sulphate free, or substantially
free, from iron, which consists in treating an aqueous solution of crude aluminium
sulphate with calcium. fluoride, then adding a solution of an alkali carbonate or
hydrate to precipitate iron, and then mechanically separating the liquid from the
solid products of the reaction.
2. The process of producing an insoluble aluminium compound, free or substan-
tially free from iron, which consists in treating an aqueous solution of crude
aluminium sulphate with. calcium fluoride, then adding a solution of an alkali
carbonate or hydrate to precipitate the iron, removing said iron, and then treating
said solution with a further quantity of said alkali carbonate or hydrate to
precipitate said aluminium compound..
3. The process of making an insoluble aluminium: compound which consists in
combining aluminium sulphate and calcium. fluoride to form an aluminium fluor-
sulphate solution, and adding, thereto an alkali carbonate or hydrate.
Dated this 6th day of September 1893
DAY, DAVIES & HUNT,.
321, High Holborn, London, Agents for the Applicant.
DAY, DAVIES & HUNT,.
321, High Holborn, London, Agents for the Applicant.