The iron ore pelletizing industry utilizes the grate-kilnprocess to dry and sinter the pellets into finished product.The grate-kiln process has a known deposit formation issuethat needs to be further understood. Combustion ofpulverised coal in the rotary kiln generates fly ash particles;in addition to that, particles generated from disintegratediron ore pellets are also entrained in the process gas stream.The combined effect of both sources of particles cantherefore contribute to the deposit formation in the process.In this work, particle- and deposit formation were studiedboth from a full-scale grate-kiln plant (40 MW) and from apilot-scale pulverised coal fired furnace (400 kW). Particleswere collected with a water-cooled probe with nitrogen gasas dilution medium at the tip of the probe. The particleswere separated simultaneously with a pre-cyclone and a 13stages low-pressure impactor during samplings. Depositswere collected with a refractory plate which was attachedat the tip of a water-cooled probe, exposed to the hightemperature (>1100 °C) process gas stream. Particles anddeposits were characterized with an environmentalscanning electron microscope and a scanning electronmicroscope that equipped with energy dispersivespectroscopy detector. A comparison of particle and depositcharacteristics between the grate-kiln plant and the pilotscale pulverised coal fired furnace is presented in this paper,with focus on the potential influence of disintegrated ironore pellets on the particle- and deposit formation process.