Development of superduty silica bricks with indigenous raw materials which
are known to be abundant, was investigated in the National Metallurgical Laboratory.
Three samples of quartzites from Jamda, Mihijam and Hyderabad were studied.
This study has revealed that crypto-crystalline variety of Jamda quartzite which
is very low in alumina, can be used successfully for the manufacture of superduty
silica brick by proper granulometric control, high pressure forming and firing under
strictly controlled conditions. The product thus obtained has the requisite properties
of a superduty quality brick. The addition of low alumina quartzite fines to
graded Mihijam quartzite did not effect any tangible improvement in the physical
properties of silica brick specimen made out of the mix, probably due to the
very friable nature of this low alumina quartzite from Hyderabad. However,
appreciable improvement in porosity, permeability, refractoriness under load etc.
could be attained by proper forming and by improved processing methods as
adopted in the case of Jamda quartzite. |