Fly ash particles spheroidization using low temperature plasma energy

The paper presents the investigations on producing spherical particles 65-110 μm in size using the energy of low temperature plasma (LTP). These particles are based on flow ash produced by the thermal power plant in Seversk, Tomsk region, Russia. The obtained spherical particles have no defects and are characterized by a smooth exterior surface. The test bench is designed to produce these particles. With due regard for plasma temperature field distribution, it is shown that the transition of fly ash particles to a state of viscous flow occurs at 20 mm distance from the plasma jet. The X-ray phase analysis is carried out for the both original state of fly ash powders and the particles obtained. This analysis shows that fly ash contains 56.23 wt.% SiO₂; 20.61 wt.% Al₂O₃ and 17.55 wt.% Fe₂O₃ phases that mostly contribute to the integral (experimental) intensity of the diffraction maximum. The LTP treatment results in a complex redistribution of the amorphous phase amount in the obtained spherical particles, including the reduction of O₂Si, phase, increase of O₂₂Al₂₀ and Fe₂O₃ phases and change in Al, O density of O₂₂Al₂₀ chemical unit cell.