| During the processing of rice, about 35% of paddy is obtained as
husk, which on ignition produces friable ash containing mostly silica
in amorphous form and little amount of Fe20 3, Al20a, CaO, MgO,
K20, P20 5 etc, besides varied amount of free carbon depending
upon the method of burning. This ash may be used for the production
of high alite cements in lieu of quartz, which demands high grinding
energy and is known for slow reactivity. CaF, CuO, PbO, Mn02
and Sn02 have been examined as mineralizers during laboratory
scale burning of raw mix (with LSF = 99.33), prepared from rice
husk ash. CuO was found to act in fairly low (0.5%) concentration.
ZnO and Mn02 were also found to be highly effective. Mn02 acted
more favourably at 1400°C and above and when the addition was
1 % or more. The mineralizing action of Sn02 was somewhat moderate
and PbO exhibited only a feeble action. The order of mineralizing
effectiveness changed with temperature as well as concentration.
Rapid cooling was necessary when CaF2 and more than 0.5% CuO
were used as mineralizers. |
