STUDY OF ALUMINUM HYDROXIDE POWDER
PREPARED BY CHEMICAL DISPERSION OF ALUMINUM AND ITS ALLOY
A. D. Shlyapin,
A. Yu. Omarov,
A. Kh. Khairi,
and Yu. G. Trifonov
Translated from Novye Ogneupory, No. 10, pp. 27 – 32, October, 2012.
Original article submitted July 6, 2012.
Aluminum hydroxide is a secondary product during operation of a hydrogen generator. An alkaline reaction
proceeding between aluminum or aluminum alloy and caustic soda may be considered as a chemical disper
sion method with preparation of nanodispersed aluminum hydroxide powder. Particle fineness and morphol
ogy, and also aluminum hydroxide powder phase composition, are different with different preparation meth
ods, and therefore x-ray-phase, petrographic, and dimensional analyses are performed for three powder sam
ples. Two powder samples are studied, prepared by chemical dispersion of aluminum (sample 1) and silumin
AK7 (sample 2). Results for industrially produced aluminum hydroxide powder, prepared by the Bayer
method (sample 3) are studied for comparison.
Keywords: hydrogen generator, aluminum hydroxide, chemical dispersion, aluminum, silumin, gibbsite,
bayerite, powder dispersed composition, reaction kinetics, powder preparation methods.
Aluminum hydroxide is produced as a secondary product
during operation of a hydrogen generator. This occurs with
action of aqueous caustic soda solution on aluminum within
the vessel of a hydrogen generator cartridge with the follow
ing main chemical reaction:
4Al + 3NaOH + 6H
¯ + 3NaAlO
The hydrogen produced is used for direct purposes as a
fuel, and aluminum hydroxide is separated as a waste prod
uct of the generator operating cycle. Reaction (1) may also
be considered as an original technological approach to pre
paring aluminum hydroxide powder with nanosize particles,
classified in contemporary technical publications as a chemi
cal dispersion method [1, 2]. The aluminum hydroxide
7separated may fulfil the function of a starting substance for
preparing nanosize aluminum oxide powder. Commercially
pure aluminum and silumin AK7 are also used in the work as
ALUMINUM HYDROXIDE POWDER PROPERTIES
Two powder samples were prepared as a result of reac-
tion of aluminum and its alloy with an aqueous alkaline solu-
tion. Sample 1 was prepared as a result reaction of commer-
cial grade aluminum with an aqueous caustic soda solution;
sample 2 is an aluminum hydroxide deposit with reaction of
silumin with aqueous caustic soda solution. Sample 3 was
analyzed in order to prepare comparative data. Sample 3 is
commercially produced aluminum hydroxide prepared by
the Bayer method (Al
O, GOST 11841, analytical
grade classification, from the Donetsk Chemical Reagent
The phase composition and morphology of deposit parti
cles was studied by x-ray-phase and petrographic analyses.
In order to evaluate hydroxide particle size distribution an
electroacoustic method and laser diffraction were used.
X-ray-phase analysis (XPA) was performed in a
DRON-3 device by a standard procedure . Diffraction pat
terns were recorded with CuK
-radiation (nickel filter), tube
voltage 30 kV, and current strength 20 mA. In order to iden
tify phases data of the ASTM card index were used.
Results of XPA are presented in Table 1. As may be seen,
the main crystal phases comprising powder sample 1 (Fig. 1a )
Refractories and Industrial Ceramics Vol. 53, No. 5, January, 2013
1083-4877/13/05305-0317 © 2013 Springer Science+Business Media New York
FGBOU VPO Moscow State Industrial University, Moscow, Russia.