Dependence of energy exchange between plasma and soda-lime-silica glass particles on the particle size, powder feed-rate and nozzle insertion length during in-flight thermal treatment for glassification by induction thermal plasmas has been studied. For the numerical investigation into the plasma-particle energy exchange dynamics during melting and vaporization of particles, a thermofluid plasma-particle interaction model has been developed taking into account the strong plasma-particle interactions and particle loading effects. It is found that heat transfer to the particles depends strongly on the particles' size, powder feed-rate, nozzle insertion length, and plasma discharge parameters. Thus, for the efficient thermal treatment of particles, the above parameters should be optimized. © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.