Microwave Energy for Expanding Perlite Ore

Abstract

Perlite is an igneous mineral composed by silicon, aluminum, oxygen and water. It can be expanded by heating it upat temperatures above 870 °C, then it becomes plastic, and the steam formed inside pressures out of the mineral.Maximum expansion is possible if the particles are heated up quickly, since the expansion degree strongly dependson the remaining water in the particles at the time that they reach the temperature where they become plastic. Thetypical expansion process consist in pouring the particles in rotary kilns operated with natural gas, but it is proposed inthis research that the particles can be heated quickly with microwaves at 2.45 GHz. Particles of 0.08 cm and 0.018 cmof average diameter were expanded 10 to 20 times.