Improvements in the Treatment of Bauxite or similar Minerals for the Purpose of Obtaining Alkali-aluminates or Alumina Hydrate.
Year: 1892

page_text: Date of Application, 17th Mar., 1892
Complete Specification Left, 13th Dec., 1892-Accepted, 21st Jan., 1893
PROVISIONAL SPECIFICATION.
Improvements in the Treatment of Bauxite or similar Minerals
for the Purpose of Obtaining Alkali-aluminates or Alumina
Hydrate.
I, CHARLES JOSEPH BAYER, Doctor of Philosophy, and Manufacturing Chemist,
of Elabuga, Russia, do hereby declare the nature of this invention to be as
follows:-
The Specification of my Patent No. 10093, dated 19. July 1887, described a
process for decomposing aluminates and thereby obtaining solutions in which the
ratio between the molecules of Al,O, and of Na,O is approximately as 1:6.
According to my observations, these solutions act in many cases like caustic soda.
According to the Specification mentioned above, these solutions are boiled down,
again mixed with bauxite, and then exposed to the heat of the reverberatory
furnace, in order to obtain from them crude aluminate, which, after dissolving and
filtering, is again subjected to decomposition.
My experiments have shown, that these solutions, when concentrated by
evaporation to about 40-44° Bé, are capable of directly dissolving the alumina
out of the bauxite, if the latter is treated with the concentrated solutions, while
constantly stirring, at a pressure of 3-4 atmospheres and the corresponding
temperature (160-172° C.) for a period of from 1 to 2 hours.
If the bauxite was pulverised sufficiently, and if there is only a small quantity of
silica present, the alumina is dissolved almost completely, leaving only a trace, or a
quantity sufficient to form with the silicic acid (that it may have dissolved) and
with the corresponding amount of soda, the well-known double salt Na,O ÁĻO,
3 SiO, +9 ag, which forms a residue.
In using ordinary French bauxite containing about 61 per cent. of Al,O, and
about 3 per cent. of SiO,, 59 per cent. of the alumina enters into solution, provided
that decomposed liquor and bauxite are brought together in such proportions, that
the treatment produces a solution containing Al,O, and Na, in proportions
varying between 1:1-75 and 1: 1.85. This corresponds to a yield equal to at least
96 per cent. of the alumina present.
The apparatus necessary or suitable for this purpose is a high pressure boiler
made of iron or steel plate and provided with the usual fittings, such as safety
valve, pressure gauge, an agitator, feed opening and discharge pipe. For a given
production, the size of the boiler and the consumption of fuel are very small.
A boiler of 2 meter length and 1 meter diameter, for instance, is sufficient for the
daily treatment of 4000 to 5000 kilos. of bauxite, while the fuel and labour are only
abouts of those required for one or more reverberatory furnaces having a corre-
sponding effect. Besides, such a boiler produces a solution ready made, instead of
a crude aluminate in a dry condition, from which the solution must be prepared, as
is the case with reverberatory furnaces.
The red ferrugineous residue, which remains in the boiler after treatment,
settles easily and may, after some practice, be easily filtered and washed. Owing
to its high percentage of iron and its low percentage of alumina, it may be
utilized by smelting it together with other iron ores, so as to recover the iron.
Under the name of bauxite I wish to include all minerals having a composition
imilar to bauxite.
Dated this 17th day of March 1892.
FAIRFAX & WETTER,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in the Treatment of Bauxite or similar Minerals
for the Purpose of Obtaining Alkali-aluminates or Alumina
Hydrate.
I, CHARLES JOSEPH BAYER, Doctor of Philosophy, and Manufacturing Chemist,
of Elabuga, Russia, do hereby declare the nature of this invention and in what
manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement :-
The Specification of my Patent No. 10093, dated 19 July 1887 describes a
process for decomposing aluminates and thereby obtaining solutions in which the
ratio between the molecules of Al,O, and of Na,O is approximately as 1:6. I
have found, that these solutions act in many cases like caustic soda. According to
the Specification mentioned above, these solutions are boiled down, again mixed
with bauxite, and then exposed to the heat of the reverberatory furnace, in order
to obtain from them crude aluminate, which after dissolving and filtering, is again
subjected to decomposition.
My experiments have shown, that these solutions, when concentrated by
evaporation to about 40-44° Bé., are capable of directly dissolving the alumina
out of the bauxite, if the latter is treated with the concentrated solutions, while
constantly stirring, at a pressure of 3-4 atmospheres and the corresponding
temperature (160—172° C.) for a period of from 1 to 2 hours.
If the bauxite was pulverised sufficiently, and if there is only a small quantity of
silica present, the alumina is dissolved almost completely, leaving only a trace, or a
quantity sufficient to form with the silicic acid (that it may have dissolved) and
with the corresponding amount of soda, the well known double salt Na,O ÁI,O,
3 SiO, +9 ag, which forms a residue.
In using ordinary French bauxite containing about 61 per cent. of ALO, and
about 3 per cent. of SiO„, 59 per cent. of the alumina enters into solution, provided
that decomposed liquor and bauxite are brought together in such proportions, that
the treatment produces a solution containing AIO, and Na, in proportions
varying between 1: 1-75 and 1: 1-85. This corresponds to a yield equal to at
least 96 per cent. of the alumina present.
The apparatus necessary or suitable for this purpose is a high pressure boiler
made of iron or steel plate and provided with the usual fittings, such as safety
valve, pressure gauge, an agitator, feed opening and discharge pipe. For a given
production, the size of the boiler and the consumption of fuel are very small. A
boiler of 2 meter length and 1 meter diameter, for instance, is sufficient for the
daily treatment of 4000 to 5000 kilos. of bauxite, while the fuel and labour may be
reduced to about of those required for one or more reverberatory furnaces
having a corresponding effect. Besides, such a boiler produces a solution ready
made, instead of a crude aluminate in a dry condition, from which the solution
must be prepared as is the case with reverberatory furnaces.
The red ferrugineous residue, which remains in the boiler after treatment,
settles easily and may, after some practice, be easily filtered and washed. Owing
to its high percentage of iron and its low percentage of alumina, it may be
utilized by smelting it together with other iron ores, so as to recover the iron.
Under the name of bauxite I wish to include all minerals having a composition
similar to bauxite.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is ;-
The utilization of the residual lianoz or solution obtained by decomnosine a

page_text: of 1887, which consists in causing the said liquor, after concentration to 40-44° Bé.,
to act upon finely pulverised bauxite, at a temperature of about 160—172º C.,
while constantly stirring, in order to extract alumina from the bauxite.
Dated this 13th day of December 1892.
FAIRFAX & WETTER,
433, Strand, London, Agents.