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SYNTHETIC HIGH ALUMINA AGGREGATES
(58 TO 86% ALUMINA)
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A wide variety of high
alumina refractories in the form of bricks or any shapes and monolithics possessing
stringent qualities are required, to meet the increasing demand
by iron and steel, cement, glass, chemical and other industries. The
efficiency of the user industries and the quality of the product
produced depends mainly on the performance of the refractory products they
use, which, in turn, broadly the quality and performance of the
refractory materials from which these refractories are made and their
fabrication techniques. Appropriate quality mineral-based high alumina raw
materials in the form of kyanite/ sillimanite/ alusite/ diaspore/ bauxite/
corrundum are becoming scarce. New sources are the beneficiated concentrates
of low-grade minerals and development/import of substitute materials in the
form of synthetic products like sintered/fused high alumina aggregates of
mullite, mullite-corrundum and corrundum. The requirement of high quality
synthetic aggregate is reported to be quite high and the demand of such
materials is mostly met through imports of synthetic sinter mullite/
tabular-alumina/high alumina cements etc. The technology for making
sintered synthetic mullite/mullite corrundum/corrundum, involve high
technology requiring the use of high cost infra-structural inputs in the form
of high cost high duty briquetting press machine for pelletisation, high
temperature kiln for sintering the synthetic compositions around 1600-1850°C,
like shaft kiln/ rotary kiln and other high cost processing equipment and
machinery. The Central Glass and
Ceramic Institute, Calcutta, has developed the process which involves
innovation and improvement in the technology eliminating the use of high cost
and high technology infrastructure, as also reducing the cost of production
by introducing new technique of sintering synthetic products containing 58 to
86% alumina. PROCESS Institute had developed a
process of manufacturing synthetic high alumina aggregate and their products
through new technique of sintering by utilizing indigenous raw materials of
appropriate qualities. Fireclay, china clay, technical/ hydrated alumina and
some other chemical additives are employed. . Conventional machinery and
equipment may be used. The process may also be easily adaptable by small
scale and mini scale sectors. In this process, products are matured at
temperature ranging from 1350°C to 1550°C. Different steps of the
process include blending of the raw materials, commination to fine sizes,
dewatering, mixing with green bond, shaping into hollow ware, drying the
green compacted wares, firing and reduction of particle sizes to appropriate
graded fractions. Ranges of physico-chemical, thermal and mineralogical
characteristics of the sintered aggregates are as follows:
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NRDC
National Research Development Corporation, a
Government of India Enterprise, is a premier technology Transfer Corporation
with four decades of experience. It has helped establish over one thousand
projects in the small and medium scale sector. The supply of technologies and
services to entrepreneurs extend both in the developing and developed countries
like USA, Germany, Malaysia, Myanmar, Nepal, Senegal, Madagascar, Indonesia
Philippines, Vietnam, Sri Lanka, Kenya, Brazil, Bangladesh and Egypt.
Advantages of Indian technologies:
- Low
capital investment
- High
employment potential
- Maximum
use of local raw materials and manpower resources
- Adaptable levels of sophistication
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Services offered by NRDC
- Process
know-how
- Pre-investment
studies
- Feasibility
/ project reports
- Detailed
engineering
- Turn
key projects
- Equity
capital participation
- Training
in operation of plants
- Raw materials
and products testing