A NEW OR IMPROVED PROCESS FOR MANUFACTURING ANHYDROUS ALUMINA
Year: 1882

page_text: LETTERS PATENT to Henri Adrien Bonneville, of the British and Foreign
A com-
Patent Offices, 8 rue de la Chaussée d'Antin, Paris, France, and 90 Cannon
Street, in the city of London, Patent Agent for an Invention of A NEW
OR IMPROVED PROCESS FOR MANUFACTURING ANHYDROUS ALUMINA
munication from Felix Gardair and Thaddé Gladysz, two
Marseille in the Republic of France
persons resident at
PROVISIONAL SPECIFICATION left by the said Henry Adrien Bonneville at
the Office of the Commissioners of Patents on the 23rd October 1882.
HENRI ADRIEN BONNEVILLE of the British and Foreign Patent Offices, 8 rue
de la Chaussée d'Autin, Paris, France, and 90 Cannon Street in the city of London
Patent Agent, A NEW OR IMPROVED PROCESS FOR MANUFACTURING ANHYDROUS
ALUMINA, communicated to me by Felix Gardair, and Thaddé Gladysz two
persons resident at Marseille, in the republic of France,
The invention consists of three main operations, viz,
1° The preparation of Sulphate of Alumina.
2° The precipitation of Alumina by Chlorhydric acid.
3° The decomposition of Chlorhydrate of Alumina.
This sulphate is prepared by submitting pale Bauxite whilst warm, to the action
of Sulphuric acid of different degrees of Concentration; for this purpose, Sulphuric
Acid of 60° Bé is used and with Bauxite, Alum cake is obtained, but acid of 25°
to 30° Be is always to be preferred.
The mixture of Acid and Bauxite is brought to a boil, and kept at this
temperature long enough to secure the perfect saturation of the acid, when the
liquids of sulphate are clarified by separating the vitrifiable earth and the alumina
not acted upon, either by decanting or filtration.
The limpid sulphate Alumina is first concentrated to 30° to 35° Be. As soon
as the sulphate is cold, it is submitted to the action of cold Chlorhydric gas. The
reaction of the Chlorhydric gas upon the aluminous solution is sharp, and there is
ID 71

page_text: a considerable escape of heat. Very soon there may be perceived the small crystals
of Chlorhydrate of Alumina, which in consequence of their great specific weight,
fall to the bottom of the absorbers. When the limpid sulphate of Alumina, can no
longer absorb Chlorhydric gas, the operation may be looked upon as finished.
Almost the whole of the Alumina is therefore found precipitated in the form of
Chlorhydrato of Alumina. The other water, consisting of a mixture of Sulphuric
and Chlorhydric acids may be employed in other applications upon Bauxite. On
the first application of the heat, and in proportion as the sulphuric acid becomes
more concentrated, the Chlorhydric gas, being distilled, is conducted into absorbers,
to precipitate more Alumina.
By proceeding under the conditions above mentioned, and with the Chlorhydric
gas almost dry, the 95% of Alumina contained in the sulphate is precipitated.
The crystals of Chlorhydrate of Alumina are separated from their mother water
by simple filtration in closed vessels. For this purpose however, apparatuses mny
be used in which filtration is effected by means of compressed air or a vacuum.
The Chlorhydrate of Alumina should finally be cleared and dried.
As soon as the crystals have been properly died, calcination is proceeded with.
Strictly speaking, dark red is sufficient to cause decomposition. The result of this
division is, that on the one hand white anhydrous alumina, free from Silica and
containing only slight traces of oxyde of iron is obtained, and on the other hand,
chlorhydric gas which is conducted into absorbers provided with sulphate.
This decomposition is accomplished either in a mutto oven, or in a reverberatory
gas furnace. It will be seen that in this process, the two reagents employed in
extracting the pure alumina from its ore, become continually and successively
regenerated.
Although theoretically, a given quantity of the two mineral acids may serve
indefinitely, in practice it will be necessary to introduce small quantities of the two
rengents regularly, so as to compensate for the loss unavoidable in all industrial
operations, but in any case, this loss will be reduced to a minimum, and will depend
as much upon the perfection of the apparatus, as on the care taken in the
operation.
.

page_text: J
the 2nd April 1883.
HENRI ADRIEN BONNEVILLE, of the British and Foreign Patent Offices, 8, rue de
la: Chaussée d'Antin Paris, France, and 90 Cannon Street, in the city of London,
Patent Agent, A. NEW OR IMPROVED. PROCESS FOR MANUFACTURING ANHYDROUS
ALUMINA, communicated to me by Felix Gardair, and Thaddé Gladysz, two persons
resident at Marseille, in the republic of France,
The Invention consists of three main operations, viz
1 The preparation of Sulphate of Alunina.
2nd The precipitation of Alumina by Chlorhydric Acid.
3rd The decomposition of Chlorhydrate of Alumina.
1st Preparation of Sulphate of Alumina. This sulphate is prepared by submitting
pale Bauxite whilst warm, to the action of Sulphuric Acid of different degrees of
[concentration; for this purpose, Sulphuric Acid of 60° Bé is used, and with Bauxite,
Alum cake is obtained, but Acid of 25° to 30° Be is always to be preferred.
The mixture of Acid and Bauxite is brought to a boil, and kept at this
temperature long enough to secure the perfect saturation of the acid, when the
liquids of Sulphate are clarified by separating the vitrifiable earth and the Alumina
not acted upon, either by decanting or filtration.
2nd Precipitation of Alumina by Chlorhydric Acid. The limpid sulphate of
Alumina is first concentrated to 30° to 35° Bé. As soon as the sulphate is cold, it
is submitted to the action of Cold Chlorhydric gas. The reaction of the Chlorhydric
gas upon the aluminous solution is sharp, and there is a considerable escape of heat.
Very soon there may be perceived the small crystals of Chlorbydrate of Alumina,.
which in consequence of their great specific weight, fall to the bottom of the
absorbers. When the liquid sulphate of Alumina can no longer absorb Chlorhydric
gas, the operation may be looked upon as finished.
Almost the whole of the Alumina is therefore found precipitated in the form of
Chlorhydrate of Alumina. The mother water, consisting of a mixture of Sulphuric
and Chlorhydric Acids, may be employed in other applications upon Bauxite. On
the first application of the heat, and in proportion as the sulphuric acid becomes
more concentrated, the Chlorhydric gas being distilled is conducted into absorbers
to precipitate more Alumina.
By proceeding under the conditions above mentioned, and with the Chlorhydric
gas alinost dry, the 95% of Alumina contained in the Sulphate is precipitated.
The crystals of Chlorhydrate of Alumina are separated from their mother water
by simple filtration in closed vessels. For this purpose however, apparatuses may
be used in which filtration is effected by means of compressed air or a vacuum.
The chlorhydrate of Alumina should finally be cleared and dried.
3rd Decomposition of Chlo hydrate of Alumina. As soon as the crystals have
been properly dried, calcination is proceeded with. Strictly speaking, dark red is
sufficient to cause decomposition. The result of this division is, that on the one
hand, white anhydrous alumina, free from silica, and containing only slight traces
of oxyde of iron is obtained, and on the other hand, chlorhydric gas which is
conducted into absorbers provided with sulphate.
This decomposition is accomplished either in a muffle oven or in a reverberatory
gas furnace. It will be seen that in this process, the two reagents employed in
extracting the pure alumina from its ore become continually and successively
regenerated.

page_text: n
Although theoretically, a given quantity of the two mineral acids may serve
indefinitely, in practice, it will be necessary to introduce small quantities of the two
reagents regularly so as to compensate for the loss unavoidable in all industrial
operations but in any case, this will be reduced to a minimum, and will depend
as much upon the perfection of the apparatus, as on the caro taken in the.
operation.
Having thus described the nature of the snid Invention, and the inanner in
which the same is to be performed, I claim and desire to secure, by Royal Letters
Patent:
1 The method of manufacturing Anhydrous Alumina, consisting in preparing.
crystallized chlorhydrate of Alumina by means of Chlorhydric acid, and
gad The successive regeneration of the two reagents, vis:
Sulphuric acid to dissolve Alumina from Bauxite, and
precipitate it in the form of Chlorhydrate or acid liquid.
Chlorhydric acid to
In witness whereof I. the said Henri Adrien Bonneville, have hereunto set
my hand and seal, this
in the year of our Lord One
day of
thousand eight hundred and eighty three.