MANUFACTURING AND EQUIPMENT
HIGH-ALUMINA REFRACTORIES BASED ON ANDALUSITE
WITH INCREASED SERVICE LIFE
V. P. Migal’,
A. P. Margishvili,
V. V. Skurikhin,
and A. A. Kovalenko
Translated from Novye Ogneupory, No. 5 pp. 21 – 26, May 2009.
Original article submitted April 20, 2009.
Results are provided for the development and introduction into production of high-alumina objects of different
grades based on andalusite. Physiochemical indices, and fields of application for objects in various heating
units are indicated.
Keywords: High-alumina refractories, andalusite, mullite, mercury porosimetry.
High-alumina refractories are some of the most used.
Traditional high-alumina materials, prepared on the basis of
alumina or bauxite, do not respond to the contemporary level
of requirements for reliability and endurance. A solution of
this problem is production of new refractories based on anda-
lusite. Such qualities of andalusite as high purity, sufficient
volumetric stability, low porosity, active mullitization, low
thermal conductivity, give rise to its use in producing high
quality refractories .
The preference for using andalusite within the composi
tion of refractory objects compared with high-alumina
chamotte is due to the physicochemical features of this mate
rial. Andalusite is a natural “mullite former”. During high-
temperature firing it is converted into mullite, and the excess
silica forms a comparatively small amount of glass phase,
exhibiting high porosity, and it is concentrated in capillary
pores of a grain  (Fig. 1). Thus, after firing of refractory
based on andalusite it becomes and entirely new material,
consisting of primary and secondary mullite and a small
amount of highly bonded glass phase, that provides new re
fractory properties incomparable with those of high-alumina
refractories of other forms.
Currently for lining air coolers and the bottom glass fur
naces, lining steel-pouring ladles, mobile mixers and anode
firing furnaces, there is extensive use of domestic mullite and
mullite-corundum grades MKV-72, MLS-62, MKS-72,
MLLD, based on high-alumina chamotte, prepared from alu
mina and kaolin. For these refractories there is typically a
significant amount of glass (Fig. 2a ) exhibiting reduced
toughness at high temperature and nonuniform distribution,
that promotes a reduction the high-temperature strength of
objects under load, low resistance to cracking due to
microstress development, that arises during thermal shock.
Specialists of OAO BKO have developed and introduced
into production high-alumina objects grade MLUT-62,
MLUT-69, MKP-72, manufactured on the basis of andalu-
site. Objects may be used for lining mobile mixers, iron-car-
rying and steel-pouring ladles, the upper cone and upper part
of the shaft of a blast furnace, and also anode firing furnaces
Refractories and Industrial Ceramics Vol. 50, No. 3, 2009
1083-4877/09/5003-0178 © 2009 Springer Science+Business Media, Inc.
OAO Borovichi Refractory Combine, Borovichi, Novgorod Re
Fig. 1. Fragment of the microstructure of a fired andalusite grain:
1 ) mullite; 2 ) pores; 3 ) glass phase (localized in capillary pores of a